ApoE lipoproteins in the central nervous system under homeostasis and role in Alzheimer’s disease and related disorders

ApoE2 lipoproteins secreted from astrocytes form slightly larger particles than ApoE3 and ApoE4 lipoproteins.

“However, ApoE2 lipoproteins secreted from astrocytes form slightly larger particles than ApoE3 and ApoE4 lipoproteins [17–20].”

• cites [17] Strickland MR, Rau MJ, Summers B, Basore K, Wulf J 2nd, Jiang H, Chen Y, Ulrich JD, Randolph GJ, Zhang R, et al. Apolipoprotein E secreted by astrocytes forms antiparallel dimers in discoidal lipoproteins. Neuron. 2024;112:1100–e11091105. sourceSupported
• cites [18] Morikawa M, Fryer JD, Sullivan PM, Christopher EA, Wahrle SE, DeMattos RB, O’Dell MA, Fagan AM, Lashuel HA, Walz T, et al. Production and characterization of astrocyte-derived human apolipoprotein E isoforms from immortalized astrocytes and their interactions with amyloid-beta. Neurobiol Dis. 2005;19:66–76. sourceDisputed

  In “Purification and size analysis of apoE-containing lipoproteins secreted by immortalized astrocytes” (page unavailable), the authors report no consistent particle-size difference between apoE isoforms or cell lines. This is contrary to the claim that astrocyte-secreted ApoE2 particles are slightly larger than ApoE3 and ApoE4 particles. (LLM, conf=0.88)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured
• cites [19] DeMattos RB, Brendza RP, Heuser JE, Kierson M, Cirrito JR, Fryer J, Sullivan PM, Fagan AM, Han X, Holtzman DM. Purification and characterization of astrocyte-secreted apolipoprotein E and J-containing lipoproteins from wild-type and human apoE transgenic mice. Neurochem Int. 2001;39:415–25. sourceNot checked — no full text of the source
• cites [20] Fagan AM, Holtzman DM, Munson G, Mathur T, Schneider D, Chang LK, Getz GS, Reardon CA, Lukens J, Shah JA, LaDu MJ. Unique lipoproteins secreted by primary astrocytes from wild type, apoE (-/-), and human apoE transgenic mice. J Biol Chem. 1999;274:30001–7. sourceCould not verify

  The Results report that astrocyte-secreted apoE4 particles are slightly larger on average than apoE3 particles. The study compares wild-type, apoE3, and apoE4 astrocytes, but does not measure apoE2 astrocyte particles; a search for apoE2 particle size found no comparison supporting the claimed ordering. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

The ability of ApoE to efflux lipids from microglia plays a significant role in disease pathogenesis as lipid loaded microglia are less able to contribute to tissue repair.

“The ability of ApoE to efflux lipids from microglia also plays a significant role in disease pathogenesis as lipid loaded microglia are less able to contribute to tissue repair [12].”

• cites [12] Cantuti-Castelvetri L, Fitzner D, Bosch-Queralt M, Weil MT, Su M, Sen P, Ruhwedel T, Mitkovski M, Trendelenburg G, Lutjohann D, et al. Defective cholesterol clearance limits remyelination in the aged central nervous system. Science. 2018;359:684–8. sourcePartly supported

  The main text (p. 2) identifies APOE as supporting lipid efflux and reports that APOE-knockout mice accumulate myelin debris in lesion phagocytes and have impaired lesion restitution. It also links excessive cholesterol accumulation in phagocytes to limited lesion recovery. These findings support the tissue-repair mechanism in demyelinating lesions, but the claim extends it to disease pathogenesis generally, which this paper does not establish. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

ApoE lipoproteins secreted by different cell types carry unique lipids and proteins which alter ApoE function.

“ApoE lipoproteins (LpE) secreted by different cell types carry unique lipids and proteins which alter its function.”

• Also stated in: § Background · plain

  “This cargo differs based on the cellular origin of ApoE and ApoE isoform [11].”

• cites [11] Strickland MR, Wang Z, Golden LR, Wang H, Lu P, Ren Y, Tabor GT, Zhao N, Ulrich JD, Han X, et al. Lipidome and proteome of astrocyte and microglia ApoE lipoprotein reveal differences based on cell type and ApoE isoform. J Lipid Res 2026;101000. sourcePartly supported

  The Discussion (page not provided) reports that the lipid and protein composition of ApoE lipoproteins differs by cellular source. It also says that how associated proteins alter lipoprotein function is currently unknown and that the effects of cosecreted proteins and lipids require future study. The claim therefore overstates the functional finding. (LLM, conf=0.90)

  Experimental — accuracy not yet measured

Pharmacologically altering ABCA1 expression using an LXR agonist has been shown to ameliorate Aβ and tau pathology.

“Pharmacologically altering ABCA1 expression using an LXR agonist has been shown to ameliorate Aβ and tau pathology [47, 48].”

• cites [47] Litvinchuk A, Suh JH, Guo JL, Lin K, Davis SS, Bien-Ly N, Tycksen E, Tabor GT, Remolina Serrano J, Manis M, et al. Amelioration of Tau and ApoE4-linked glial lipid accumulation and neurodegeneration with an LXR agonist. Neuron. 2024;112:384–e403388. sourcePartly supported

  The Discussion (page unavailable) reports that the LXR agonist GW3965 increased brain ABCA1 expression and reduced tau pathology in TE4 mice. The Results (page unavailable) also report reduced phosphorylated tau. These passages do not show that the agonist ameliorated Aβ pathology; the amyloid finding appears only in the title of a cited reference about ABCA1 overexpression. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [48] Fitz NF, Cronican A, Pham T, Fogg A, Fauq AH, Chapman R, Lefterov I, Koldamova R. Liver X receptor agonist treatment ameliorates amyloid pathology and memory deficits caused by high-fat diet in APP23 mice. J Neurosci. 2010;30:6862–72. sourcePartly supported

  The Discussion reports that LXR agonist treatment increases Abca1 expression and Aβ degradation, and describes reduced Aβ aggregation and increased clearance. The paper also reports reduced amyloid pathology in high-fat-diet-fed APP23 mice. It does not report an effect on tau pathology, so that part of the claim is unsupported. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Secreted ApoE is taken back up and transits through the recycling endosome pathway in multiple cell types, including astrocytes.

“However, this interpretation is complicated by the fact that secreted ApoE is taken back up and transits through the recycling endosome pathway in multiple cell types, including astrocytes [32–36].”

• cites [32] Fan J, Stukas S, Wong C, Chan J, May S, DeValle N, Hirsch-Reinshagen V, Wilkinson A, Oda MN, Wellington CL. An ABCA1-independent pathway for recycling a poorly lipidated 8.1 nm apolipoprotein E particle from glia. J Lipid Res. 2011;52:1605–16. sourcePartly supported

  The discussion section, “ApoA-I stimulates glial apoE recycling and lipidation in primary glia” (page unavailable), reports recycling of internalized apoE in several cell types and suggests that glia share this pathway. It specifically describes delivery to recycling endosomes in hepatocytes, but does not establish that apoE transits through recycling endosomes in astrocytes. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [33] Heeren J, Grewal T, Jackle S, Beisiegel U. Recycling of apolipoprotein E and lipoprotein lipase through endosomal compartments in vivo. J Biol Chem. 2001;276:42333–8. sourceNot checked — no full text of the source
• cites [34] Braun NA, Mohler PJ, Weisgraber KH, Hasty AH, Linton MF, Yancey PG, Su YR, Fazio S, Swift LL. Intracellular trafficking of recycling apolipoprotein E in Chinese hamster ovary cells. J Lipid Res. 2006;47:1176–86. sourcePartly supported

  The paper reports that internalized apoE traffics through the endosomal recycling compartment in CHO cells (Abstract; page unavailable). The Discussion also describes apoE recycling in hepatocytes and macrophages, but our copy does not establish transit through that compartment in those cells or address astrocytes. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [35] Farkas MH, Weisgraber KH, Shepherd VL, Linton MF, Fazio S, Swift LL. The recycling of apolipoprotein E and its amino-terminal 22 kDa fragment. J Lipid Res. 2004;45:1546–54. sourcePartly supported

  The paper reports uptake and recycling of apoE in hepatocytes and notes recycling in macrophages, fibroblasts, and hepatoma cell lines (Abstract; page unavailable). It does not report recycling in astrocytes, and its Discussion (page unavailable) proposes endosomal routes as possibilities rather than establishing that apoE transits through a recycling endosome pathway. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [36] Heeren J, Grewal T, Laatsch A, Rottke D, Rinninger F, Enrich C, Beisiegel U. Recycling of Apoprotein E Is Associated with Cholesterol Efflux and High Density Lipoprotein Internalization. J Biol Chem. 2003;278:14370–8. sourcePartly supported

  The Results and Discussion (page unavailable) describe TRL-derived apoE entering endosomes and being recycled in human fibroblasts and hepatoma cells. They do not establish that secreted apoE is taken back up, or that this pathway occurs in astrocytes. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

LXR agonist treatment has also been shown to be beneficial in reducing Aβ pathology in the context of traumatic brain injury.

“LXR agonist treatment has also been shown to be beneficial in reducing Aβ pathology in the context of traumatic brain injury [49].”

• cites [49] Loane DJ, Washington PM, Vardanian L, Pocivavsek A, Hoe HS, Duff KE, Cernak I, Rebeck GW, Faden AI, Burns MP. Modulation of ABCA1 by an LXR agonist reduces beta-amyloid levels and improves outcome after traumatic brain injury. J Neurotrauma. 2011;28:225–36. sourceSupported

In contrast to LpE in rodent CSF, human CSF-LpE are predominantly present as 11-24 nm spherical particles.

“It is important to note that in contrast to LpE in rodent CSF, human CSF-LpE are predominantly present as 11–24 nm spherical particles, therefore understanding the structural changes that occur when ApoE is present in spherical lipoprotein will be essential to understanding its role in vivo [62–64].”

• cites [62] Guyton JR, Miller SE, Martin ME, Khan WA, Roses AD, Strittmatter WJ. Novel large apolipoprotein E-containing lipoproteins of density 1.006–1.060 g/ml in human cerebrospinal fluid. J Neurochem. 1998;70:1235–40. sourcePartly supported

  The Results and Discussion (page unavailable) report human CSF lipoproteins averaging 11.6 ± 2.2 nm and a larger apoE-containing fraction averaging 18.3 ± 6.6 nm. A figure passage says the larger particles appeared spherical, but the paper does not establish that human CSF apoE lipoproteins are predominantly 11–24 nm spherical particles or make the stated comparison with rodent CSF. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [63] LaDu MJ, Gilligan SM, Lukens JR, Cabana VG, Reardon CA, Van Eldik LJ, Holtzman DM. Nascent astrocyte particles differ from lipoproteins in CSF. J Neurochem. 1998;70:2070–81. sourceNot checked — no full text of the source
• cites [64] Pitas RE, Boyles JK, Lee SH, Hui D, Weisgraber KH. Lipoproteins and their receptors in the central nervous system. Characterization of the lipoproteins in cerebrospinal fluid and identification of apolipoprotein B,E(LDL) receptors in the brain. J Biol Chem. 1987;262:14352–60. sourceNot checked — no full text of the source

Nonlipidated ApoE that is present in microglial lysosomes has been shown to result in ApoE aggregation and seeding of Aβ, resulting in Aβ plaque formation.

“Nonlipidated ApoE that is present in microglial lysosomes has been shown to result in ApoE aggregation and seeding of Aβ, resulting in Aβ plaque formation suggesting that more lipidated ApoE is resilient to aggregation and decreased seeding of plaques (Fig. 2C) [45].”

• cites [45] Kaji S, Berghoff SA, Spieth L, Schlaphoff L, Sasmita AO, Vitale S, Büschgens L, Kedia S, Zirngibl M, Nazarenko T, et al. Apolipoprotein E aggregation in microglia initiates Alzheimer’s disease pathology by seeding β-amyloidosis. Immunity. 2024. sourceCould not verify

  Our indexed copy contains a correction notice (Main text, p. 263), not the original article’s findings. It mentions APOE+ and Aβ-42+ lysosomes, but does not address whether nonlipidated ApoE aggregates there or seeds Aβ plaques. Searches for lipidation, aggregation, and plaque seeding found no decisive passage. (LLM, conf=0.72)

  Experimental — accuracy not yet measured

In the context of Aβ pathology, knockout of ABCA1 led to an increase in Aβ plaques.

“In the context of Aβ pathology, knockout of ABCA1 led to an increase in Aβ plaques (Fig. 2A) [40–42].”

• cites [40] Koldamova R, Staufenbiel M, Lefterov I. Lack of ABCA1 considerably decreases brain ApoE level and increases amyloid deposition in APP23 mice. J Biol Chem. 2005;280:43224–35. sourceNot checked — no full text of the source
• cites [41] Hirsch-Reinshagen V, Maia LF, Burgess BL, Blain JF, Naus KE, McIsaac SA, Parkinson PF, Chan JY, Tansley GH, Hayden MR, et al. The absence of ABCA1 decreases soluble ApoE levels but does not diminish amyloid deposition in two murine models of Alzheimer disease. J Biol Chem. 2005;280:43243–56. sourcePartly supported

  The Results section (‘Deficiency of ABCA1 Increases Amyloid Deposition in Tg-SwDI/B Mice’; page unavailable) reports a significant twofold increase in amyloid burden after ABCA1 knockout in Tg-SwDI/B mice. But the Results section on Aβ deposition reports no significant increase in APP/PS1 mice, so the claim omits an important model-specific qualification. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [42] Wahrle SE, Jiang H, Parsadanian M, Hartman RE, Bales KR, Paul SM, Holtzman DM. Deletion of Abca1 increases Abeta deposition in the PDAPP transgenic mouse model of Alzheimer disease. J Biol Chem. 2005;280:43236–42. sourceSupported

Systemic ApoE does not enter the central nervous system due to the blood brain barrier.

“However, human liver transplant studies show that systemic ApoE does not enter into the central nervous system due to the blood brain barrier and knockout of hepatic ApoE does not have an effect on Aβ pathology in the APP/PS1-21 mouse model of Aβ amyloidosis [15, 16].”

• cites [15] Huynh TV, Wang C, Tran AC, Tabor GT, Mahan TE, Francis CM, Finn MB, Spellman R, Manis M, Tanzi RE, et al. Lack of hepatic apoE does not influence early Abeta deposition: observations from a new APOE knock-in model. Mol Neurodegener. 2019;14:37. sourceSupported
• cites [16] Linton MF, Gish R, Hubl ST, Butler E, Esquivel C, Bry WI, Boyles JK, Wardell MR, Young SG. Phenotypes of apolipoprotein B and apolipoprotein E after liver transplantation. J Clin Invest. 1991;88:270–81. sourcePartly supported

  The Results (page not available in our copy) report that the CSF ApoE phenotype did not change to the donor liver’s phenotype after transplantation, implying that most CSF ApoE is produced locally. This supports limited entry of systemic ApoE, but the paper does not establish that none enters the central nervous system or that the blood-brain barrier completely prevents it. The separate mouse-model claim is not attributed to this source. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Use of LXR agonists is complicated by side effects induced by activation of LXR/RXR in the liver causing hepatic steatosis and hypertriglyceridemia.

“Currently, use of LXR agonists is complicated by side effects induced by activation of LXR/RXR in the liver causing hepatic steatosis and hypertriglyceridemia [50, 51].”

• cites [50] Fessler MB. The challenges and promise of targeting the Liver X Receptors for treatment of inflammatory disease. Pharmacol Ther. 2018;181:1–12. sourceSupported
• cites [51] Ma Z, Deng C, Hu W, Zhou J, Fan C, Di S, Liu D, Yang Y, Wang D. Liver X Receptors and their Agonists: Targeting for Cholesterol Homeostasis and Cardiovascular Diseases. Curr Issues Mol Biol. 2017;22:41–64. sourceSupported

Generation of discoidal ApoE using recombinant protein and lipidation with lipids such as POPC and DMPC result in the formation of discoidal lipoprotein similar in diameter and conformation to astrocyte secreted human LpE.

“Generation of discoidal ApoE using recombinant protein and lipidation with lipids such as 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) and dimyristoylphosphatidylcholine (DMPC) result in the formation of discoidal lipoprotein similar in diameter and conformation to astrocyte secreted human LpE [20, 56].”

• cites [20] Fagan AM, Holtzman DM, Munson G, Mathur T, Schneider D, Chang LK, Getz GS, Reardon CA, Lukens J, Shah JA, LaDu MJ. Unique lipoproteins secreted by primary astrocytes from wild type, apoE (-/-), and human apoE transgenic mice. J Biol Chem. 1999;274:30001–7. sourcePartly supported

  The Results describe lipoproteins secreted by astrocytes expressing human apoE3 or apoE4 and report that the particles are likely predominantly discoidal, with diameters of about 11–15 nm. The paper does not report generating particles by lipidating recombinant apoE with POPC or DMPC, or compare those particles’ diameter and conformation with astrocyte-secreted particles. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [56] Jonas A, Steinmetz A, Churgay L. The number of amphipathic alpha-helical segments of apolipoproteins A-I, E, and A-IV determines the size and functional properties of their reconstituted lipoprotein particles. J Biol Chem. 1993;268:1596–602. sourceNot checked — no full text of the source

• AssumptionRests on an assumption: In vitro recombinant ApoE lipoprotein particles recapitulate native central nervous system LpE structure and function sufficiently to infer in vivo behavior.

Recent results using cryo-electron microscopy in combination with monoclonal Fab and F'(ab)2 fragments showed that ApoE is present in discoidal particles.

“Recent results using cryo-electron microscopy in combination with monoclonal Fab and F’(ab)2 fragments showed that ApoE is present in a discoidal particles [17].”

• cites [17] Strickland MR, Rau MJ, Summers B, Basore K, Wulf J 2nd, Jiang H, Chen Y, Ulrich JD, Randolph GJ, Zhang R, et al. Apolipoprotein E secreted by astrocytes forms antiparallel dimers in discoidal lipoproteins. Neuron. 2024;112:1100–e11091105. sourceSupported

Evidence from ApoA1, a related apolipoprotein, suggests that the degree of lipidation of discoidal ApoA1 alters its conformation.

“Evidence from ApoA1, a related apolipoprotein, also suggests that the degree of lipidation of discoidal ApoA1 alters its conformation [59].”

• cites [59] He Y, Pavanello C, Hutchins PM, Tang C, Pourmousa M, Vaisar T, Song HD, Pastor RW, Remaley AT, Goldberg IJ, et al. Flipped C-Terminal Ends of APOA1 Promote ABCA1-Dependent Cholesterol Efflux by Small HDLs. Circulation. 2024;149:774–87. sourceSupported

In PS19 mice, LXR agonist treatment reduces tau-mediated neurodegeneration.

“Treatment of PS19 mice with an LXR agonist reduces tau-mediated neurodegeneration [47].”

• cites [47] Litvinchuk A, Suh JH, Guo JL, Lin K, Davis SS, Bien-Ly N, Tycksen E, Tabor GT, Remolina Serrano J, Manis M, et al. Amelioration of Tau and ApoE4-linked glial lipid accumulation and neurodegeneration with an LXR agonist. Neuron. 2024;112:384–e403388. sourcePartly supported

  The Introduction identifies the treated mice as P301S tau transgenic mice carrying human ApoE4 (TE4), and the Discussion reports that the LXR agonist GW3965 reduced tau-associated neurodegeneration in those mice. The claim omits the ApoE4 condition, so the paper does not establish the effect for PS19 mice generally. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Nascent ApoE secreted by astrocytes which typically contain two ApoE per particle would have lower avidity to LDLR than more mature particles.

“This would suggest that nascent ApoE secreted by astrocytes which typically contain two ApoE per particle would have lower avidity to LDLR than more mature particles [17, 57].”

• cites [17] Strickland MR, Rau MJ, Summers B, Basore K, Wulf J 2nd, Jiang H, Chen Y, Ulrich JD, Randolph GJ, Zhang R, et al. Apolipoprotein E secreted by astrocytes forms antiparallel dimers in discoidal lipoproteins. Neuron. 2024;112:1100–e11091105. sourcePartly supported

  The Results report two ApoE proteins per astrocyte-secreted lipoprotein particle. The Discussion cites higher LDLR binding affinity for large four-ApoE DMPC particles than for ellipsoidal DPPC particles, but does not compare nascent astrocyte-secreted particles with more mature particles. The proposed lower avidity during maturation is therefore an inference, not a finding this source establishes. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [57] Peters-Libeu CA, Newhouse Y, Hatters DM, Weisgraber KH. Model of biologically active apolipoprotein E bound to dipalmitoylphosphatidylcholine. J Biol Chem. 2006;281:1073–9. sourcePartly supported

  The Figure 1 section says that apoE–DPPC particles with two apoE molecules are expected to have lower LDLR-binding activity than apoE–DMPC particles with four. The LDLR-binding Activity section identifies the two-apoE particles as an experimental apoE4–DPPC preparation. Our copy does not establish that astrocyte-secreted nascent particles typically contain two apoE molecules or compare nascent with mature particles. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Astrocytic LpE is enriched in phospholipid transfer protein (PLTP) and clusterin (Clu, also known as ApoJ).

“Astrocytic LpE was found to be enriched in proteins such as phospholipid transfer protein (PLTP) and clusterin (Clu, also known as ApoJ), both of which play a role in AD disease pathogenesis (Fig. 4A) [11, 19, 101].”

• cites [11] Strickland MR, Wang Z, Golden LR, Wang H, Lu P, Ren Y, Tabor GT, Zhao N, Ulrich JD, Han X, et al. Lipidome and proteome of astrocyte and microglia ApoE lipoprotein reveal differences based on cell type and ApoE isoform. J Lipid Res 2026;101000. sourceSupported
• cites [19] DeMattos RB, Brendza RP, Heuser JE, Kierson M, Cirrito JR, Fryer J, Sullivan PM, Fagan AM, Han X, Holtzman DM. Purification and characterization of astrocyte-secreted apolipoprotein E and J-containing lipoproteins from wild-type and human apoE transgenic mice. Neurochem Int. 2001;39:415–25. sourceNot checked — no full text of the source
• cites [101] Vuletic S, Peskind ER, Marcovina SM, Quinn JF, Cheung MC, Kennedy H, Kaye JA, Jin LW, Albers JJ. Reduced CSF PLTP activity in Alzheimer’s disease and other neurologic diseases; PLTP induces ApoE secretion in primary human astrocytes in vitro. J Neurosci Res. 2005;80:406–13. sourceNot checked — no full text of the source

ApoE produced from different cell types may differentially affect disease outcomes.

“Knockout of ApoE in astrocytes versus microglia has differing impacts on disease pathogenesis in mouse models of Aβ amyloidosis suggesting that ApoE produced from different cell types may differentially affect disease outcomes [96, 97].”

• cites [96] Mahan TE, Wang C, Bao X, Choudhury A, Ulrich JD, Holtzman DM. Selective reduction of astrocyte apoE3 and apoE4 strongly reduces Abeta accumulation and plaque-related pathology in a mouse model of amyloidosis. Mol Neurodegener. 2022;17:13. sourceSupported
• cites [97] Henningfield CM, Arreola MA, Soni N, Spangenberg EE, Green KN. Microglia-specific ApoE knock-out does not alter Alzheimer’s disease plaque pathogenesis or gene expression. Glia. 2022;70:287–302. sourceSupported

The increased binding of ApoE to LDLR compared to LDL is attributable to stoichiometry.

“For illustration, the increased binding of ApoE to LDLR compared to LDL is attributable to stoichiometry.”

• cites [57] Peters-Libeu CA, Newhouse Y, Hatters DM, Weisgraber KH. Model of biologically active apolipoprotein E bound to dipalmitoylphosphatidylcholine. J Biol Chem. 2006;281:1073–9. sourcePartly supported

  The Figure 1 caption says that the number of apoE molecules per phospholipid particle influences LDLR binding: particles with four apoE molecules are expected to bind more strongly than those with two. It does not attribute stronger LDLR binding by apoE than by LDL to stoichiometry; LDL is used in the binding assay as a competitor, not evaluated in that comparison. No page number is available in our copy. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Knockout of LRP1 in neurons resulted in reduced amyloid pathology.

“However, this effect may be cell type specific as knockout of LRP1 in neurons resulted in reduced amyloid pathology [88, 89].”

• cites [88] Tachibana M, Holm ML, Liu CC, Shinohara M, Aikawa T, Oue H, Yamazaki Y, Martens YA, Murray ME, Sullivan PM, et al. APOE4-mediated amyloid-beta pathology depends on its neuronal receptor LRP1. J Clin Invest. 2019;129:1272–7. sourcePartly supported

  The Introduction and Results and Discussion report that neuronal LRP1 deletion reversed increased hippocampal Aβ deposition in APP/PS1 mice expressing human APOE4. The claim omits that APOE4 and brain-region qualification: the Results and Discussion report no effect on cortical Aβ concentrations in the human-APOE models and describe a previous finding of worsened pathology with murine Apoe. Page numbers are not provided for these passages. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [89] Strickland MR, Holtzman DM. Dr. Jekyll and Mr. Hyde: ApoE explains opposing effects of neuronal LRP1. J Clin Invest. 2019;129:969–71. sourcePartly supported

  The “ApoE4-mediated seeding of Aβ” section reports that neuronal LRP1 knockout prevents the increase in amyloid pathology caused by ApoE4. The claim omits that genotype condition: the “Therapeutic strategies for Aβ and ApoE genotype” section cautions that lowering neuronal LRP1 may be ineffective or deleterious in ApoE3 homozygotes. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Knockout of human ApoE3 and ApoE4 in astrocytes of transgenic mice results in markedly decreased Aβ plaque pathology despite microglia continuing to produce ApoE.

“Knockout of human ApoE3 and ApoE4 in astrocytes of transgenic mice results in markedly decreased Aβ plaque pathology despite microglia continuing to produce ApoE [96].”

• cites [96] Mahan TE, Wang C, Bao X, Choudhury A, Ulrich JD, Holtzman DM. Selective reduction of astrocyte apoE3 and apoE4 strongly reduces Abeta accumulation and plaque-related pathology in a mouse model of amyloidosis. Mol Neurodegener. 2022;17:13. sourceSupported

ApoE binding to C1q attenuates inflammation by high-affinity binding to the C1q complex, interrupting the complement cascade.

“ApoE binding to C1q was found to attenuate inflammation through high affinity binding to the C1q complex where it interrupts the complement cascade [105].”

• cites [105] Yin C, Ackermann S, Ma Z, Mohanta SK, Zhang C, Li Y, Nietzsche S, Westermann M, Peng L, Hu D, et al. ApoE attenuates unresolvable inflammation by complex formation with activated C1q. Nat Med. 2019;25:496–506. sourceSupported

Global ApoE knockout strongly suppresses neurodegeneration.

“Further, global knockout of ApoE also very strongly suppresses neurodegeneration and knockout of APOE4 from astrocytes also strongly attenuates tau-mediated degeneration [92, 106].”

• cites [92] Shi Y, Yamada K, Liddelow SA, Smith ST, Zhao L, Luo W, Tsai RM, Spina S, Grinberg LT, Rojas JC, et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature. 2017;549:523–7. sourceSupported
• cites [106] Wang C, Xiong M, Gratuze M, Bao X, Shi Y, Andhey PS, Manis M, Schroeder C, Yin Z, Madore C, et al. Selective removal of astrocytic APOE4 strongly protects against tau-mediated neurodegeneration and decreases synaptic phagocytosis by microglia. Neuron. 2021;109:1657–e16741657. sourceSupported

PLTP has reduced activity in human Alzheimer's disease patient CSF.

“PLTP, which is reported to transfer phospholipids to HDL in plasma, has reduced activity in human AD patient CSF [101, 102].”

• cites [101] Vuletic S, Peskind ER, Marcovina SM, Quinn JF, Cheung MC, Kennedy H, Kaye JA, Jin LW, Albers JJ. Reduced CSF PLTP activity in Alzheimer’s disease and other neurologic diseases; PLTP induces ApoE secretion in primary human astrocytes in vitro. J Neurosci Res. 2005;80:406–13. sourceNot checked — no full text of the source
• cites [102] Vuletic S, Li G, Peskind ER, Kennedy H, Marcovina SM, Leverenz JB, Petrie EC, Lee VM, Galasko D, Schellenberg GD, Albers JJ. Apolipoprotein E highly correlates with AbetaPP- and tau-related markers in human cerebrospinal fluid. J Alzheimers Dis. 2008;15:409–17. sourceSupported

Studies in humans, which express CETP, reveal that CSF-LpE is primarily present as spherical particles rather than the primarily discoidal particles observed in rodent and canine CSF.

“Studies in humans, which express CETP, reveal that CSF-LpE is primarily present as spherical particles rather than the primarily discoidal particles observed in rodent and canine CSF [9, 64].”

• cites [9] Koch S, Donarski N, Goetze K, Kreckel M, Stuerenburg H-J, Buhmann C, Beisiegel U. Characterization of four lipoprotein classes in human cerebrospinal fluid. J Lipid Res. 2001;42:1143–51. sourcePartly supported

  The Affinity chromatography of CSF-Lp section reports relatively homogeneous populations of human CSF lipoproteins and says electron microscopy showed spherical particles; the paper also identifies CSF-LpE as a distinct class. These passages support the human-particle finding, but do not establish the claim’s comparison with primarily discoidal rodent and canine CSF particles or its CETP framing. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [64] Pitas RE, Boyles JK, Lee SH, Hui D, Weisgraber KH. Lipoproteins and their receptors in the central nervous system. Characterization of the lipoproteins in cerebrospinal fluid and identification of apolipoprotein B,E(LDL) receptors in the brain. J Biol Chem. 1987;262:14352–60. sourceNot checked — no full text of the source

Clearance of Aβ through direct association with ApoE or through binding to ApoE receptors decreases amyloid pathology in mouse models.

“Clearance of Aβ through direct association with ApoE or through binding to ApoE receptors decreases amyloid pathology in mouse models.”

• cites [86] Kim J, Castellano JM, Jiang H, Basak JM, Parsadanian M, Pham V, Mason SM, Paul SM, Holtzman DM. Overexpression of low-density lipoprotein receptor in the brain markedly inhibits amyloid deposition and increases extracellular A beta clearance. Neuron. 2009;64:632–44. sourcePartly supported

  The Results report that LDLR overexpression increased extracellular Aβ elimination and markedly reduced amyloid deposition in APP/PS1 mice. The Discussion says clearance of an Aβ–ApoE complex or Aβ alone through receptors is possible, but does not establish either route as the mechanism. The claim presents those proposed routes as demonstrated. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [85] Verghese PB, Castellano JM, Garai K, Wang Y, Jiang H, Shah A, Bu G, Frieden C, Holtzman DM. ApoE influences amyloid-beta (Abeta) clearance despite minimal apoE/Abeta association in physiological conditions. Proc Natl Acad Sci U S A. 2013;110:E1807–1816. sourcePartly supported

  The Discussion says Aβ can bind directly to lipoprotein receptors such as LDLR for clearance, and that LDLR modifies plaque pathology in an APP mouse model. But the Significance section rejects direct ApoE–Aβ association as the proposed clearance mechanism; it instead reports that ApoE competes with Aβ for cellular clearance pathways. The claimed direct-association route is therefore not supported. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [87] Liu CC, Hu J, Zhao N, Wang J, Wang N, Cirrito JR, Kanekiyo T, Holtzman DM, Bu G. Astrocytic LRP1 Mediates Brain Abeta Clearance and Impacts Amyloid Deposition. J Neurosci. 2017;37:4023–31. sourcePartly supported

  The sections on astrocytic LRP1 deletion report impaired Aβ clearance and greater amyloid plaque deposition in APP/PS1 mice, supporting the receptor-mediated clearance part of the claim. The Discussion does not establish that direct Aβ association with ApoE reduces pathology; instead, it says ApoE can compete with Aβ for LRP1-dependent uptake and may compromise clearance. Page numbers are not available in our copy. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

• AssumptionRests on an assumption: Findings from mouse models of Aβ amyloidosis and tauopathy are informative about human Alzheimer’s disease pathogenesis.

Decreasing microglia ApoE4 modestly decreased Aβ deposition.

“Microglial specific knockout of murine apoE does not alter amyloid-β pathology in contrast to astrocyte specific ApoE knockout [97]; though decreasing microglia ApoE4 modestly decreased Aβ deposition [98].”

• cites [98] Yin Z, Rosenzweig N, Kleemann KL, Zhang X, Brandao W, Margeta MA, Schroeder C, Sivanathan KN, Silveira S, Gauthier C, et al. APOE4 impairs the microglial response in Alzheimer’s disease by inducing TGFbeta-mediated checkpoints. Nat Immunol. 2023;24:1839–53. sourceSupported

There is a stepwise increase in LpE affinity with the number of ApoE proteins per particle.

“This leads to a stepwise increase in LpE affinity with the number of ApoE proteins per particle [57].”

• cites [57] Peters-Libeu CA, Newhouse Y, Hatters DM, Weisgraber KH. Model of biologically active apolipoprotein E bound to dipalmitoylphosphatidylcholine. J Biol Chem. 2006;281:1073–9. sourcePartly supported

  The Figure 1 LDLR-binding passage says that the number of apoE molecules per particle influences receptor-binding activity and predicts lower activity for particles with two apoE molecules than for those with four. It does not establish a stepwise increase in affinity across successive apoE counts; the two particle types also contain different phospholipids. No page number is available in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

In a recent large study of atherosclerotic cardiovascular disease, the CETP inhibitor obicetrapib significantly attenuated increases in the marker for brain amyloidosis p-tau217 compared to placebo.

“In a recent large study of atherosclerotic cardiovascular disease, the CETP inhibitor obicetrapib significantly attenuated increases in the marker for brain amyloidosis p-tau217 compared to placebo [82].”

• cites [82] Davidson MH, Szarek M, Scheltens P, Vijverberg E, Hsieh A, Ditmarsch M, Kling D, Curcio D, Nicholls SJ, Ray KK, et al. Effect of obicetrapib, a potent cholesteryl ester transfer protein inhibitor, on p-tau217 levels in patients with cardiovascular disease. J Prev Alzheimers Dis. 2026;13:100394. sourceSupported

Larger LpE secreted by astrocytes, those with a diameter of 10-17 nm, were found to associate with Aβ.

“Larger LpE secreted by astrocytes, those with a diameter of 10–17 nm, were found to associate with Aβ [18].”

• cites [18] Morikawa M, Fryer JD, Sullivan PM, Christopher EA, Wahrle SE, DeMattos RB, O’Dell MA, Fagan AM, Lashuel HA, Walz T, et al. Production and characterization of astrocyte-derived human apolipoprotein E isoforms from immortalized astrocytes and their interactions with amyloid-beta. Neurobiol Dis. 2005;19:66–76. sourceSupported

Mutations in ApoE that reduce binding to LDLR, namely ApoE2, but also to HSPG and LRP1, like the APOE Christchurch variant, also decrease tau seeding in wildtype mice and in the context of Aβ pathology.

“Mutations in ApoE that reduce binding to LDLR, namely ApoE2, but also to HSPG and LRP1, like the APOE Christchurch variant, also decrease tau seeding in wildtype mice and in the context of Aβ pathology [91, 92].”

• cites [91] Chen Y, Song S, Parhizkar S, Lord J, Zhu Y, Strickland MR, Wang C, Park J, Tabor GT, Jiang H, et al. APOE3ch alters microglial response and suppresses Abeta-induced tau seeding and spread. Cell. 2024;187:428–e445420. sourceNot checked — no full text of the source
• cites [92] Shi Y, Yamada K, Liddelow SA, Smith ST, Zhao L, Luo W, Tsai RM, Spina S, Grinberg LT, Rojas JC, et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature. 2017;549:523–7. sourceCould not verify

  The Abstract reports lower tau levels in P301S/ApoE2 mice than in P301S/ApoE4 mice, but that is not a finding about tau seeding. The Methods (Animals) describe P301S mice with ApoE2, ApoE3, ApoE4 or no ApoE; our copy does not address reduced LDLR, HSPG or LRP1 binding, the Christchurch variant, or decreased tau seeding in wild-type mice or mice with Aβ pathology. Searches for tau seeding and the named receptors and variant did not locate such a finding. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

Astrocyte-specific APOE4 knockout strongly attenuates tau-mediated degeneration.

“Further, global knockout of ApoE also very strongly suppresses neurodegeneration and knockout of APOE4 from astrocytes also strongly attenuates tau-mediated degeneration [92, 106].”

• cites [92] Shi Y, Yamada K, Liddelow SA, Smith ST, Zhao L, Luo W, Tsai RM, Spina S, Grinberg LT, Rojas JC, et al. ApoE4 markedly exacerbates tau-mediated neurodegeneration in a mouse model of tauopathy. Nature. 2017;549:523–7. sourcePartly supported

  The paper reports that absence of ApoE was strongly protective against tau-mediated neurodegeneration, and that neurons cultured with ApoE-knockout mixed glia showed less injury (Abstract, page unavailable). It also reports changes in reactive astrocytes, but does not report an astrocyte-specific APOE4 knockout. The cell-specific part of the claim is therefore unsupported. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [106] Wang C, Xiong M, Gratuze M, Bao X, Shi Y, Andhey PS, Manis M, Schroeder C, Yin Z, Madore C, et al. Selective removal of astrocytic APOE4 strongly protects against tau-mediated neurodegeneration and decreases synaptic phagocytosis by microglia. Neuron. 2021;109:1657–e16741657. sourceSupported

Knockout of ApoE in astrocytes versus microglia has differing impacts on disease pathogenesis in mouse models of Aβ amyloidosis.

“Knockout of ApoE in astrocytes versus microglia has differing impacts on disease pathogenesis in mouse models of Aβ amyloidosis suggesting that ApoE produced from different cell types may differentially affect disease outcomes [96, 97].”

• cites [96] Mahan TE, Wang C, Bao X, Choudhury A, Ulrich JD, Holtzman DM. Selective reduction of astrocyte apoE3 and apoE4 strongly reduces Abeta accumulation and plaque-related pathology in a mouse model of amyloidosis. Mol Neurodegener. 2022;17:13. sourcePartly supported

  The Methods and Results describe selective removal of astrocytic APOE in an amyloidosis mouse model and report reduced Aβ pathology. The Discussion suggests that apoE from astrocytes and microglia could have different effects, but this paper does not report a microglia-specific knockout or establish differing outcomes between the two knockouts. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [97] Henningfield CM, Arreola MA, Soni N, Spangenberg EE, Green KN. Microglia-specific ApoE knock-out does not alter Alzheimer’s disease plaque pathogenesis or gene expression. Glia. 2022;70:287–302. sourcePartly supported

  The Abstract reports that microglia-specific ApoE knockout in 5xFAD mice increased average Aβ plaque size but did not change plaque load or CAA. The Discussion says the roles of microglial and astrocytic ApoE need to be differentiated; this study kept astrocytic ApoE intact and did not test astrocyte-specific knockout. It therefore supports the microglial side, but not the claimed comparison between the two knockouts. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Comparing recombinant ApoE lipidated with either DPPC or DMPC showed that particles made with DMPC had higher affinity to LDLR than particles made with DPPC.

“Comparing recombinant ApoE lipidated with either DPPC or DMPC showed that particles made with DMPC had higher affinity to LDLR than particles made with DPPC [57].”

• cites [57] Peters-Libeu CA, Newhouse Y, Hatters DM, Weisgraber KH. Model of biologically active apolipoprotein E bound to dipalmitoylphosphatidylcholine. J Biol Chem. 2006;281:1073–9. sourcePartly supported

  The LDLR-binding Activity section reports a competition assay comparing apoE4–DPPC particles with apoE–DMPC and says the DPPC particles bind LDLR with high affinity. The Figure 1 caption says DPPC particles are expected to have lower binding activity because they carry two apoE molecules per particle versus four for DMPC; it does not establish that DMPC itself confers higher LDLR affinity. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Aβ has also been reported to associate with ApoE specifically, in contrast to ApoJ containing lipoprotein for instance, in human CSF.

“Aβ has also been reported to associate with ApoE specifically, in contrast to ApoJ containing lipoprotein for instance, in human CSF [83, 84].”

• cites [83] Suzuki T, Tozuka M, Yamauchi K, Sugano M, Nakabayashi T, Okumura N, Hidaka H, Katsuyama T, Higuchi K. Predominant Apolipoprotein J Exists as Lipid-poor Mixtures in Cerebrospinal Fluid. Annals Clin Lab Sci. 2002;32:369–76.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [84] LaDu MJ, Munson GW, Jungbauer L, Getz GS, Reardon CA, Tai LM, Yu C. Preferential interactions between ApoE-containing lipoproteins and Abeta revealed by a detection method that combines size exclusion chromatography with non-reducing gel-shift. Biochim Biophys Acta. 2012;1821:295–302. sourcePartly supported

  Results §3.2 reports that endogenous Aβ in the human CSF sample was associated with apoE-containing lipoproteins, and identifies a portion in an apoE/Aβ complex. The paper does not report a comparison with ApoJ-containing lipoproteins, so the claimed contrast is unsupported. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

Aβ oligomers were found to associate with poorly lipidated ApoE rather than lipidated ApoE.

“However, Aβ oligomers were found to associate with poorly lipidated ApoE rather than lipidated ApoE [85].”

• cites [85] Verghese PB, Castellano JM, Garai K, Wang Y, Jiang H, Shah A, Bu G, Frieden C, Holtzman DM. ApoE influences amyloid-beta (Abeta) clearance despite minimal apoE/Abeta association in physiological conditions. Proc Natl Acad Sci U S A. 2013;110:E1807–1816. sourcePartly supported

  The section on association with cell-secreted soluble Aβ reports minimal association between lipidated apoE3 or apoE4 and higher- or lower-order Aβ species. It does not report that Aβ oligomers preferentially associate with poorly lipidated apoE; its mention of poorly lipidated particles does not establish that comparison. Page numbers are unavailable in our copy. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Cultured microglial secreted LpE is associated with complement component 1q (C1q) and complement component 3 (C3), proteins involved in the complement cascade pathway.

“Cultured microglial secreted LpE was found to be associated with complement component 1q (C1q) and complement component 3 (C3), proteins involved in the complement cascade pathway (Fig. 4B) [11].”

• cites [11] Strickland MR, Wang Z, Golden LR, Wang H, Lu P, Ren Y, Tabor GT, Zhao N, Ulrich JD, Han X, et al. Lipidome and proteome of astrocyte and microglia ApoE lipoprotein reveal differences based on cell type and ApoE isoform. J Lipid Res 2026;101000. sourcePartly supported

  The Results section on microglia-secreted ApoE lipoproteins identifies C1q subunits C1qa and C1qb among proteins associated with the lipoproteins and describes them as involved in the complement pathway. It does not identify C3 as associated with those lipoproteins; a search for C3 found no supporting results passage. Page numbers are unavailable in our copy. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Neurons express low levels of ApoE mRNA.

“Neurons have also been reported to express low levels of ApoE mRNA and knockout of ApoE4 under control of the synapsin-1 promoter results in decreased tau-mediated neurodegeneration [110].”

• cites [110] Koutsodendris N, Blumenfeld J, Agrawal A, Traglia M, Grone B, Zilberter M, Yip O, Rao A, Nelson MR, Hao Y, et al. Neuronal APOE4 removal protects against tau-mediated gliosis, neurodegeneration and myelin deficits. Nat Aging. 2023;3:275–96. sourcePartly supported

  In Results (section ‘Removal of neuronal APOE4 diminishes disease-associated neurons and oligodendrocytes’; page not provided), the paper’s single-nucleus RNA-sequencing analysis finds APOE expression in some neurons and high expression in astrocytes. This supports neuronal APOE mRNA expression in the studied mice, but does not establish that neuronal expression is uniformly low; it also identifies neuronal clusters with high APOE expression. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

Pericyte upregulation of ApoE is associated with Aβ accumulation along vessels in an in vitro blood brain barrier model.

“Pericyte upregulation of ApoE is associated with Aβ accumulation along vessels in an in vitro blood brain barrier model [113].”

• cites [113] Blanchard JW, Bula M, Davila-Velderrain J, Akay LA, Zhu L, Frank A, Victor MB, Bonner JM, Mathys H, Lin YT, et al. Reconstruction of the human blood-brain barrier in vitro reveals a pathogenic mechanism of APOE4 in pericytes. Nat Med. 2020;26:952–63. sourceSupported

Microglia-secreted ApoE4 lipoproteins contain lower lipid amounts than particles secreted by ApoE3 microglia.

“Assessing microglia secreted LpE, ApoE4 lipoproteins were found to contain lower lipid amounts than particles secreted by ApoE3 microglia [125].”

• cites [125] Fitz NF, Nam KN, Wolfe CM, Letronne F, Playso BE, Iordanova BE, Kozai TDY, Biedrzycki RJ, Kagan VE, Tyurina YY, et al. Phospholipids of APOE lipoproteins activate microglia in an isoform-specific manner in preclinical models of Alzheimer’s disease. Nat Commun. 2021;12:3416. sourcePartly supported

  The Results section (“Common APOE dependent phospholipid signature”) reports that several phospholipid classes were higher in E3 than E4 lipoproteins. But those particles were isolated from primary astrocyte-conditioned media, not secreted by microglia. The finding also concerns phospholipids rather than total lipid amounts. (LLM, conf=0.89)

  Experimental — accuracy not yet measured

Expression of ApoE4 specifically in perivascular macrophages increases white matter damage in a model of cerebral hypoperfusion.

“Expression of ApoE4 specifically in perivascular macrophages increases white matter damage in a model of cerebral hypoperfusion [116].”

• cites [116] Anfray A, Schaeffer S, Hattori Y, Santisteban MM, Casey N, Wang G, Strickland M, Zhou P, Holtzman DM, Anrather J, et al. A cell-autonomous role for border-associated macrophages in ApoE4 neurovascular dysfunction and susceptibility to white matter injury. Nat Neurosci. 2024;27:2138–51. sourceSupported

In tauopathy, disruption of lipid droplet formation in microglia increases accumulation of endosomal/lysosomal lipids and exacerbates neurodegeneration in the PS19 mouse model.

“In the context of tauopathy, disruption of lipid droplet formation in microglia was found to increase the accumulation of endosomal/lysosomal lipids and exacerbate neurodegeneration in the PS19 mouse model of tau-mediated neurodegeneration [131].”

• cites [131] Tabor GT, Litvinchuk A, Chen Y, Allison A, Sun EW, van Lengerich B, Davis SS, West E, Schlachetzki JCM, Zeng C, et al. Inducible deletion of DGAT1 and 2 from microglia exacerbates neurodegeneration and endolysosomal lipid accumulation in male PS19 mice. Cell Rep. 2026;45:116841. sourcePartly supported

  The Introduction reports that microglial DGAT knockout increased myeloid endolysosomal accumulations and exacerbated neurodegeneration in 9.5-month-old male PS19 mice, but not female PS19 mice. The claim captures the findings but omits that sex-specific limitation. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Lipidated recombinant human ApoE isoforms form discoidal particles of similar size and conformation.

“Lipidation of recombinant, human ApoE isoforms result in discoidal particles of similar size and conformation [17, 117].”

• cites [17] Strickland MR, Rau MJ, Summers B, Basore K, Wulf J 2nd, Jiang H, Chen Y, Ulrich JD, Randolph GJ, Zhang R, et al. Apolipoprotein E secreted by astrocytes forms antiparallel dimers in discoidal lipoproteins. Neuron. 2024;112:1100–e11091105. sourcePartly supported

  The Cryo-EM of recombinant ApoE lipoproteins section reports that recombinant ApoE2, ApoE3, and ApoE4 form discoidal lipoproteins with the same antiparallel orientation. It does not establish that particles formed by the three recombinant isoforms are similar in size; the size comparison in the recombinant-lipoprotein section concerns lipid types and astrocyte-secreted particles. Page numbers are unavailable in our copy. (LLM, conf=0.83)

  Experimental — accuracy not yet measured
• cites [117] Schneeweis LA, Koppaka V, Lund-Katz S, Phillips MC, Axelsen PH. Structural analysis of lipoprotein E particles. Biochemistry. 2005;44:12525–34. sourceNot checked — no full text of the source

ApoA2 forms a disulfide-linked heterodimer with ApoE2 and ApoE3.

“Apolipoprotein A2 (ApoA2) has been found to form a disulfide linked heterodimer with ApoE2 and ApoE3 [121, 136].”

• cites [121] Weisgraber KH, Shinto LH. Identification of the disulfide-linked homodimer of apolipoprotein E3 in plasma. Impact on receptor binding activity. J Biol Chem. 1991;266:12029–34. sourceNot checked — no full text of the source
• cites [136] Weisgraber KH, Mahley RW. Apoprotein (E–A-II) complex of human plasma lipoproteins. I. Characterization of this mixed disulfide and its identification in a high density lipoprotein subfraction. J Biol Chem. 1978;253:6281–8. sourcePartly supported

  The Results identify a disulfide-linked apo(E–A-II) complex whose subunits are ApoE and ApoA2. Our copy does not identify the ApoE subunit specifically as ApoE2 or ApoE3, so it does not establish the claim for both isoforms. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

Astrocytes with human APOE isoforms knocked into the endogenous mouse Apoe allele secrete discoidal particles of overlapping size.

“Astrocytes with human APOE isoforms knocked into the endogenous mouse Apoe allele secrete discoidal particles of overlapping size.”

• cites [17] Strickland MR, Rau MJ, Summers B, Basore K, Wulf J 2nd, Jiang H, Chen Y, Ulrich JD, Randolph GJ, Zhang R, et al. Apolipoprotein E secreted by astrocytes forms antiparallel dimers in discoidal lipoproteins. Neuron. 2024;112:1100–e11091105. sourceSupported
• cites [18] Morikawa M, Fryer JD, Sullivan PM, Christopher EA, Wahrle SE, DeMattos RB, O’Dell MA, Fagan AM, Lashuel HA, Walz T, et al. Production and characterization of astrocyte-derived human apolipoprotein E isoforms from immortalized astrocytes and their interactions with amyloid-beta. Neurobiol Dis. 2005;19:66–76. sourceSupported
• cites [19] DeMattos RB, Brendza RP, Heuser JE, Kierson M, Cirrito JR, Fryer J, Sullivan PM, Fagan AM, Han X, Holtzman DM. Purification and characterization of astrocyte-secreted apolipoprotein E and J-containing lipoproteins from wild-type and human apoE transgenic mice. Neurochem Int. 2001;39:415–25. sourceNot checked — no full text of the source
• cites [20] Fagan AM, Holtzman DM, Munson G, Mathur T, Schneider D, Chang LK, Getz GS, Reardon CA, Lukens J, Shah JA, LaDu MJ. Unique lipoproteins secreted by primary astrocytes from wild type, apoE (-/-), and human apoE transgenic mice. J Biol Chem. 1999;274:30001–7. sourcePartly supported

  The Materials and Methods describe human apoE3- and apoE4-transgenic mice lacking mouse apoE, not mice with human isoforms knocked into the endogenous Apoe allele. The Results describe particles of broadly comparable size and suggest that at least some are discoidal, but report that E4 particles appear spherical in the micrographs and are larger on average. Page numbers are unavailable in our copy. (LLM, conf=0.89)

  Experimental — accuracy not yet measured

ApoE3 forms homodimers in human plasma and in the CNS.

“ApoE3 has been reported to form homodimers in human plasma and in the CNS [120, 121].”

• cites [120] Elliott DA, Halliday GM, Garner B. Apolipoprotein-E forms dimers in human frontal cortex and hippocampus. BMC Neurosci. 2010;11:23. sourceSupported
• cites [121] Weisgraber KH, Shinto LH. Identification of the disulfide-linked homodimer of apolipoprotein E3 in plasma. Impact on receptor binding activity. J Biol Chem. 1991;266:12029–34. sourceNot checked — no full text of the source

Knockout of ApoE4 under control of the synapsin-1 promoter decreases tau-mediated neurodegeneration.

“Neurons have also been reported to express low levels of ApoE mRNA and knockout of ApoE4 under control of the synapsin-1 promoter results in decreased tau-mediated neurodegeneration [110].”

• cites [110] Koutsodendris N, Blumenfeld J, Agrawal A, Traglia M, Grone B, Zilberter M, Yip O, Rao A, Nelson MR, Hao Y, et al. Neuronal APOE4 removal protects against tau-mediated gliosis, neurodegeneration and myelin deficits. Nat Aging. 2023;3:275–96. sourceSupported

The proportion of truncated proteolytic fragments of ApoC1 and ApoC2 is elevated in the CSF of human APOE ε4 carriers.

“In contrast to total ApoC1 protein levels, the proportion of truncated proteolytic fragments of ApoC1 and ApoC2 were elevated in the CSF of human APOE ε4 carriers [134].”

• cites [134] Hu Y, Meuret C, Martinez A, Yassine HN, Nedelkov D. Distinct patterns of apolipoprotein C-I, C-II, and C-III isoforms are associated with markers of Alzheimer’s disease. J Lipid Res. 2021;62:100014. sourceSupported

Microglia-conditioned media from lipid droplet-containing human iPSC-derived microglia added to iPS neurons results in tau phosphorylation and apoptosis.

“Microglia conditioned media, derived from lipid droplet containing human iPSC-derived microglia, added to iPS neurons resulted in tau phosphorylation and apoptosis [129].”

• cites [129] Haney MS, Palovics R, Munson CN, Long C, Johansson PK, Yip O, Dong W, Rawat E, West E, Schlachetzki JCM, et al. APOE4/4 is linked to damaging lipid droplets in Alzheimer’s disease microglia. Nature. 2024;628:154–61. sourceSupported

ApoE4 binds more to phosphoinositide (PIP)-containing liposomes.

“Comparing the ApoE isoforms, Lindner et al. found that ApoE4 bound more to phosphoinositide (PIP)-containing liposomes [124].”

• cites [124] Lindner K, Beckenbauer K, van Ek LC, Titeca K, de Leeuw SM, Awwad K, Hanke F, Korepanova AV, Rybin V, van der Kam EL, et al. Isoform- and cell-state-specific lipidation of ApoE in astrocytes. Cell Rep. 2022;38:110435. sourceSupported

Other brain cell types (oligodendrocytes, pericytes, vascular smooth muscle cells, perivascular fibroblasts, and perivascular macrophages) produce ApoE under different conditions.

“In addition to astrocytes and microglia, other cell types in the brain have been reported to produce ApoE under different conditions. These cells include oligodendrocytes, pericytes, vascular smooth muscle cells, perivascular fibroblasts, and perivascular macrophages [107–109].”

• cites [107] Blumenfeld J, Yip O, Kim MJ, Huang Y. Cell type-specific roles of APOE4 in Alzheimer disease. Nat Rev Neurosci. 2024;25:91–110. sourcePartly supported

  The Introduction says APOE production varies by cell type and condition, and the sections on oligodendrocytic and vascular APOE identify oligodendrocytes, pericytes, and smooth muscle cells as producers. Our copy does not establish APOE production by perivascular fibroblasts or perivascular macrophages, so it does not support the full list. No page numbers are available for these passages. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [108] Vanlandewijck M, He L, Mae MA, Andrae J, Ando K, Del Gaudio F, Nahar K, Lebouvier T, Lavina B, Gouveia L, et al. A molecular atlas of cell types and zonation in the brain vasculature. Nature. 2018;554:475–80. sourceNot checked — no full text of the source
• cites [109] Yang AC, Vest RT, Kern F, Lee DP, Agam M, Maat CA, Losada PM, Chen MB, Schaum N, Khoury N, et al. A human brain vascular atlas reveals diverse mediators of Alzheimer’s risk. Nature. 2022;603:885–92. sourcePartly supported

  The ‘AD GWAS variants in human BBB cell types’ section reports robust APOE expression in human vascular smooth muscle cells and meningeal fibroblasts; Extended Data Fig. 9c describes protein signal near larger vessels consistent with smooth muscle expression. The cited passages do not establish ApoE production by oligodendrocytes, pericytes, perivascular fibroblasts, or perivascular macrophages under different conditions. In particular, the paper identifies meningeal rather than perivascular fibroblasts as APOE-expressing. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

ApoD is enriched in astrocyte-secreted LpE.

“Apolipoprotein D (ApoD) was found to be enriched in astrocyte secreted LpE [11].”

• cites [11] Strickland MR, Wang Z, Golden LR, Wang H, Lu P, Ren Y, Tabor GT, Zhao N, Ulrich JD, Han X, et al. Lipidome and proteome of astrocyte and microglia ApoE lipoprotein reveal differences based on cell type and ApoE isoform. J Lipid Res 2026;101000. sourceSupported

LXR agonist treatment of cultured astrocytes reduces the cholesterol ester content of astrocyte-secreted LpE.

“Treatment of cultured astrocytes with an LXR agonist reduced the cholesterol ester content of astrocyte secreted LpE [11], which has been reported to drive lipofuscinosis in cells that uptake LpE-containing PUFA-CEs [75].”

• cites [11] Strickland MR, Wang Z, Golden LR, Wang H, Lu P, Ren Y, Tabor GT, Zhao N, Ulrich JD, Han X, et al. Lipidome and proteome of astrocyte and microglia ApoE lipoprotein reveal differences based on cell type and ApoE isoform. J Lipid Res 2026;101000. sourceSupported

The ApoC1 gamma haplotype increases Alzheimer's disease risk independent of ApoE.

“The ApoC1 gamma haplotype has also been found to increase AD risk independent of ApoE [135].”

• cites [135] Zhou X, Chen Y, Mok KY, Kwok TCY, Mok VCT, Guo Q, Ip FC, Chen Y, Mullapudi N, et al. Alzheimer’s disease neuroimaging I,: non-coding variability at the APOE locus contributes to the Alzheimer’s risk. Nat Commun. 2019;10:3310. sourceSupported

Lipid droplet-containing microglia are associated with the APOE ε4/ε4 genotype in human Alzheimer's disease brain.

“Lipid droplet containing microglia have been associated with the APOE ε4/ε4 genotype in human AD brain [129].”

• cites [129] Haney MS, Palovics R, Munson CN, Long C, Johansson PK, Yip O, Dong W, Rawat E, West E, Schlachetzki JCM, et al. APOE4/4 is linked to damaging lipid droplets in Alzheimer’s disease microglia. Nature. 2024;628:154–61. sourceSupported

Aβ42 levels are negatively correlated with truncated ApoC1/ApoC2 forms, suggesting greater plaque deposition.

“Aβ42 levels are negatively correlated to these truncated forms suggesting greater plaque deposition [134].”

• cites [134] Hu Y, Meuret C, Martinez A, Yassine HN, Nedelkov D. Distinct patterns of apolipoprotein C-I, C-II, and C-III isoforms are associated with markers of Alzheimer’s disease. J Lipid Res. 2021;62:100014. sourceSupported

Expression of ApoE4 in oligodendrocytes leads to cholesterol dysregulation, namely accumulation of cholesterol esters and reduced axonal myelination by oligodendrocytes.

“Expression of ApoE4 in oligodendrocytes has been reported to lead to cholesterol dysregulation, namely accumulation of cholesterol esters and reduced axonal myelination by oligodendrocytes [111].”

• cites [111] Blanchard JW, Akay LA, Davila-Velderrain J, von Maydell D, Mathys H, Davidson SM, Effenberger A, Chen CY, Maner-Smith K, Hajjar I, et al. APOE4 impairs myelination via cholesterol dysregulation in oligodendrocytes. Nature. 2022;611:769–79. sourceSupported

Microglia-secreted ApoE4 lipoprotein contains higher levels of lipoprotein lipase (LPL) and C1q than ApoE2 and ApoE3 microglia-secreted lipoproteins.

“Microglia secreted ApoE4 lipoprotein contains higher levels of lipoprotein lipase (LPL) and C1q than ApoE2 and ApoE3 microglia secreted lipoproteins [11].”

• cites [11] Strickland MR, Wang Z, Golden LR, Wang H, Lu P, Ren Y, Tabor GT, Zhao N, Ulrich JD, Han X, et al. Lipidome and proteome of astrocyte and microglia ApoE lipoprotein reveal differences based on cell type and ApoE isoform. J Lipid Res 2026;101000. sourceSupported

The degree of ApoE lipidation impacts ApoE receptor binding through changes in protein conformation and stoichiometry of ApoE molecules per lipoprotein.

“Furthermore, the degree of ApoE lipidation also impacts ApoE receptor binding through changes in protein conformation and stoichiometry of ApoE molecules per lipoprotein.”

LpE carry lipids and proteins that alter the function of ApoE.

“LpE also carry lipids and proteins that alter the function of ApoE.”

ApoE associates with lipids to form discoidal and spherical lipoproteins that carry lipid and protein cargo throughout the brain.

“ApoE associates with lipids to form discoidal and spherical lipoproteins that carry lipid and protein cargo throughout the brain.”

ApoE is present in high density lipoprotein (HDL)-like particles in the central nervous system.

“ApoE is present in high density lipoprotein (HDL)-like particles in the central nervous system.”

Different isoforms of ApoE are correlated with differences in cholesterol esters and other lipids.

“Different isoforms of ApoE are correlated with differences in cholesterol esters and other lipids.”

The lipidation state of ApoE alters its interaction with amyloid-β and tau.

“The lipidation state of ApoE also alters its interaction with amyloid-β and tau, the proteins involved in forming amyloid plaques and neurofibrillary tangles, the pathological hallmarks of AD.”

These lipids can alter the consequence of ApoE uptake by cells, shifting ApoE from a protective to a detrimental phenotype.

“These lipids can dramatically alter the consequence of ApoE uptake by cells shifting ApoE from a protective to a detrimental phenotype.”

The presence of the ε2 allele is protective relative to ε3/ε3 individuals.

“In contrast to ε4, the presence of the ε2 allele is protective relative to individuals who are ε3/ε3 [4, 6].”

• cites [4] Chen Y, Strickland MR, Soranno A, Holtzman DM. Apolipoprotein E: Structural Insights and Links to Alzheimer Disease Pathogenesis. Neuron. 2021;109:205–21. sourceNot checked yet
• cites [6] Corder EH, Saunders AM, Risch NJ, Strittmatter WJ, Schmechel DE, Gaskell PC Jr., Rimmler JB, Locke PA, Conneally PM, Schmader KE, et al. Protective effect of apolipoprotein E type 2 allele for late onset Alzheimer disease. Nat Genet. 1994;7:180–4. sourceNot checked — no full text of the source

ApoE can also be secreted in an ABCA1-independent manner following stimulation by exogenous ApoA1 or ApoE.

“ApoE can also be secreted in an ABCA1-independent (Fig. 1D) manner following stimulation by exogenous ApoA1 or ApoE [24].”

• cites [24] Huang ZH, Fitzgerald ML, Mazzone T. Distinct cellular loci for the ABCA1-dependent and ABCA1-independent lipid efflux mediated by endogenous apolipoprotein E expression. Arterioscler Thromb Vasc Biol. 2006;26:157–62. sourceNot checked — no full text of the source

ABCA1 expression is mediated by the transcription factors liver X receptor (LXR) and retinoid X receptor (RXR) that form a heterodimer to promote secretion of ApoE from astrocytes.

“Similar to other cells, ABCA1 expression is mediated by the transcription factors liver X receptor (LXR) and retinoid X receptor (RXR) that form a heterodimer to promote secretion of ApoE from astrocytes [46].”

• cites [46] Liang Y, Lin S, Beyer TP, Zhang Y, Wu X, Bales KR, DeMattos RB, May PC, Li SD, Jiang XC, et al. A liver X receptor and retinoid X receptor heterodimer mediates apolipoprotein E expression, secretion and cholesterol homeostasis in astrocytes. J Neurochem. 2004;88:623–34. sourceNot checked — no full text of the source

Overexpression of ABCA1 led to a decrease in Aβ plaques.

“In contrast, overexpression of ABCA1 led to a decrease in Aβ plaques (Fig. 2B) [43].”

• cites [43] Wahrle SE, Jiang H, Parsadanian M, Kim J, Li A, Knoten A, Jain S, Hirsch-Reinshagen V, Wellington CL, Bales KR, et al. Overexpression of ABCA1 reduces amyloid deposition in the PDAPP mouse model of Alzheimer disease. J Clin Invest. 2008;118:671–82. sourceNot checked yet

All of the ApoE present in the central nervous system is produced de novo.

“Thus, all of the ApoE present in the central nervous system is produced de novo.”

The lipidation state has important implications for binding of ApoE to different receptors and may drive preferential receptor binding, depending on the degree of ApoE lipidation.

“The lipidation state has important implications for binding of ApoE to different receptors and may drive preferential receptor binding, depending on the degree of ApoE lipidation (Fig. 3).”

In contrast to LDLR, the different lipidated ApoE isoforms bind with similar affinity to low density lipoprotein receptor-related protein 1 (LRP1).

“However, in contrast to LDLR, the different lipidated ApoE isoforms bind with similar affinity to low density lipoprotein receptor-related protein 1 (LRP1) [66].”

• cites [66] Ruiz J, Kouiavskaia D, Migliorini M, Robinson S, Saenko EL, Gorlatova N, Li D, Lawrence D, Hyman BT, Weisgraber KH, Strickland DK. The apoE isoform binding properties of the VLDL receptor reveal marked differences from LRP and the LDL receptor. J Lipid Res. 2005;46:1721–31. sourceNot checked — no full text of the source

ApoE2 has dramatically reduced binding to LDLR even when lipidated.

“In addition, ApoE2 has dramatically reduced binding to LDLR even when lipidated [55, 66, 67].”

• cites [55] Yamamoto T, Choi HW, Ryan RO. Apolipoprotein E isoform-specific binding to the low-density lipoprotein receptor. Anal Biochem. 2008;372:222–6. sourceNot checked — no full text of the source
• cites [66] Ruiz J, Kouiavskaia D, Migliorini M, Robinson S, Saenko EL, Gorlatova N, Li D, Lawrence D, Hyman BT, Weisgraber KH, Strickland DK. The apoE isoform binding properties of the VLDL receptor reveal marked differences from LRP and the LDL receptor. J Lipid Res. 2005;46:1721–31. sourceNot checked — no full text of the source
• cites [67] Simmons T, Newhouse YM, Arnold KS, Innerarity TL, Weisgraber KH. Human low density lipoprotein receptor fragment. Successful refolding of a functionally active ligand-binding domain produced in Escherichia coli. J Biol Chem. 1997;272:25531–6. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

Modulating the lipidation of ApoE results in significant effects on both amyloid and tau pathology.

“Modulating the lipidation of ApoE results in significant effects on both amyloid and tau pathology.”

Knockout of hepatic ApoE does not have an effect on Aβ pathology in the APP/PS1-21 mouse model of Aβ amyloidosis.

“However, human liver transplant studies show that systemic ApoE does not enter into the central nervous system due to the blood brain barrier and knockout of hepatic ApoE does not have an effect on Aβ pathology in the APP/PS1-21 mouse model of Aβ amyloidosis [15, 16].”

• cites [15] Huynh TV, Wang C, Tran AC, Tabor GT, Mahan TE, Francis CM, Finn MB, Spellman R, Manis M, Tanzi RE, et al. Lack of hepatic apoE does not influence early Abeta deposition: observations from a new APOE knock-in model. Mol Neurodegener. 2019;14:37. sourceNot checked yet
• cites [16] Linton MF, Gish R, Hubl ST, Butler E, Esquivel C, Bry WI, Boyles JK, Wardell MR, Young SG. Phenotypes of apolipoprotein B and apolipoprotein E after liver transplantation. J Clin Invest. 1991;88:270–81. sourceNot checked yet

Macrophages isolated from Tangier disease patients, caused by mutations that disrupt ABCA1 function, have severe hyperplasia of the golgi network indicative of a secretion defect.

“This is also demonstrated in macrophages isolated from Tangier disease patients, caused by mutations that disrupt ABCA1 function, which have sever hyperplasia of the golgi network indicative of a secretion defect [29].”

• cites [29] Robenek H, Schmitz G. Abnormal processing of Golgi elements and lysosomes in Tangier disease. Arterioscler Thromb. 1991;11:1007–20. sourceNot checked — no full text of the source

ApoE is secreted through the classical secretory pathway whereby it is produced in the endoplasmic reticulum, transits to the golgi and trans-golgi, and then is transported to the plasma membrane.

“ApoE is secreted through the classical secretory pathway whereby it is produced in the endoplasmic reticulum (Fig. 1A), transits to the golgi and trans-golgi (Fig. 1B), and then is transported to the plasma membrane [21].”

• cites [21] Kockx M, Jessup W, Kritharides L. Regulation of endogenous apolipoprotein E secretion by macrophages. Arterioscler Thromb Vasc Biol. 2008;28:1060–7. sourceNot checked — no full text of the source

The computational model of ApoE4 in discoidal particles is consistent with two ApoE being present in an antiparallel orientation similar to that described in the cryoEM model.

“The computational model of ApoE4 in discoidal particles is consistent with two ApoE being present in an antiparallel orientation similar to that described in the cryoEM model.”

• cites [61] Henry N, Krammer EM, Stengel F, Adams Q, Van Liefferinge F, Hubin E, Chaves R, Efremov R, Aebersold R, Vandenbussche G, et al. Lipidated apolipoprotein E4 structure and its receptor binding mechanism determined by a combined cross-linking coupled to mass spectrometry and molecular dynamics approach. PLoS Comput Biol. 2018;14:e1006165. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

Nonlipidated ApoE is unable to bind LDLR.

“Previous research has shown that nonlipidated ApoE is unable to bind LDLR [55, 66].”

• cites [55] Yamamoto T, Choi HW, Ryan RO. Apolipoprotein E isoform-specific binding to the low-density lipoprotein receptor. Anal Biochem. 2008;372:222–6. sourceNot checked — no full text of the source
• cites [66] Ruiz J, Kouiavskaia D, Migliorini M, Robinson S, Saenko EL, Gorlatova N, Li D, Lawrence D, Hyman BT, Weisgraber KH, Strickland DK. The apoE isoform binding properties of the VLDL receptor reveal marked differences from LRP and the LDL receptor. J Lipid Res. 2005;46:1721–31. sourceNot checked — no full text of the source

ApoE secretion occurs primarily through an ABCA1-dependent pathway.

“ApoE secretion occurs primarily through an ABCA1-dependent pathway (Fig. 1C).”

As a consequence, ApoE2 is associated with type III hyperlipidemia and the accumulation of lipids in plasma as a result of impaired ApoE remnant clearance.

“As a consequence, ApoE2 is associated with type III hyperlipidemia and the accumulation of lipids in plasma as a result of impaired ApoE remnant clearance [68, 69].”

• cites [68] Havel RJ, Kane JP. Primary dysbetalipoproteinemia: predominance of a specific apoprotein species in triglyceride-rich lipoproteins. Proc Natl Acad Sci U S A. 1973;70:2015–9. sourceNot checked — no full text of the source
• cites [69] Utermann G, Hees M, Steinmetz A. Polymorphism of apolipoprotein E and occurrence of dysbetalipoproteinaemia in man. Nature. 1977;269:604–7. sourceNot checked — no full text of the source

The degree of lipidation would be expected to alter ApoE structure in both discoidal and spherical lipoproteins.

“This is potentially applicable to ApoE and therefore the degree of lipidation would be expected to alter ApoE structure in both discoidal and spherical lipoproteins.”

• cites [59] He Y, Pavanello C, Hutchins PM, Tang C, Pourmousa M, Vaisar T, Song HD, Pastor RW, Remaley AT, Goldberg IJ, et al. Flipped C-Terminal Ends of APOA1 Promote ABCA1-Dependent Cholesterol Efflux by Small HDLs. Circulation. 2024;149:774–87. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

It is likely that ApoE is further lipidated following secretion through interaction with ABCA1.

“It is likely that ApoE is further lipidated following secretion through interaction with ABCA1, although further research is required to delineate the mechanisms underlying ApoE lipidation.”

The cryoEM studies also resulted in a low resolution model preventing detailed molecular modeling of the alpha-helical structure of ApoE.

“However, the cryoEM studies also resulted in a low resolution model preventing detailed molecular modeling of the alpha-helical structure of ApoE.”

• cites [17] Strickland MR, Rau MJ, Summers B, Basore K, Wulf J 2nd, Jiang H, Chen Y, Ulrich JD, Randolph GJ, Zhang R, et al. Apolipoprotein E secreted by astrocytes forms antiparallel dimers in discoidal lipoproteins. Neuron. 2024;112:1100–e11091105. sourceNot checked yet

Knockout of ABCA1 in mice leads to the secretion of poorly lipidated ApoE by astrocytes between 7 and 8 nm in diameter, compared to particles with a diameter between 8 and 20 nm that are secreted when ABCA1 is present.

“Knockout of ABCA1 in mice leads to the secretion of poorly lipidated ApoE by astrocytes between 7 and 8 nm in diameter, compared to particles with a diameter between 8 and 20 nm that are secreted when ABCA1 is present [25].”

• cites [25] Wahrle SE, Jiang H, Parsadanian M, Legleiter J, Han X, Fryer JD, Kowalewski T, Holtzman DM. ABCA1 is required for normal central nervous system ApoE levels and for lipidation of astrocyte-secreted apoE. J Biol Chem. 2004;279:40987–93. sourceNot checked yet

This conformational change allows ApoE to adopt a conformation suitable for binding receptors like LDLR.

“This conformational change allows ApoE to adopt a conformation suitable for binding receptors like LDLR [55].”

• cites [55] Yamamoto T, Choi HW, Ryan RO. Apolipoprotein E isoform-specific binding to the low-density lipoprotein receptor. Anal Biochem. 2008;372:222–6. sourceNot checked — no full text of the source

In astrocytes, ABCA1 was found to associate with ApoE in caveolin-1 rich domains supportive of intracellular lipidation of ApoE.

“In astrocytes, ABCA1 was found to associate with ApoE in caveolin-1 rich domains supportive of intracellular lipidation of ApoE [31].”

• cites [31] Ito J, Nagayasu Y, Miura Y, Yokoyama S, Michikawa M. Astrocyte׳s endogenous apoE generates HDL-like lipoproteins using previously synthesized cholesterol through interaction with ABCA1. Brain Res. 2014;1570:1–12. sourceNot checked — no full text of the source

LpE may compete with tau for uptake by ApoE receptors.

“LpE may also compete with tau for uptake by ApoE receptors.”

In human CSF, PLTP is present on LpE.

“In human CSF, PLTP was also shown to be present on LpE based on immunoaffinity purification of ApoE [101].”

• cites [101] Vuletic S, Peskind ER, Marcovina SM, Quinn JF, Cheung MC, Kennedy H, Kaye JA, Jin LW, Albers JJ. Reduced CSF PLTP activity in Alzheimer’s disease and other neurologic diseases; PLTP induces ApoE secretion in primary human astrocytes in vitro. J Neurosci Res. 2005;80:406–13. sourceNot checked — no full text of the source

A study using different ratios of active vs. receptor inactive ApoE showed a step wise decrease in avidity with every inactive form of ApoE added.

“An elegant study using different ratios of active vs. receptor inactive ApoE showed a step wise decrease in avidity with every inactive form of ApoE added [70].”

• cites [70] Pitas RE, Innerarity TL, Mahley RW. Cell surface receptor binding of phospholipid. protein complexes containing different ratios of receptor-active and -inactive E apoprotein. J Biol Chem. 1980;255:5454–60. sourceNot checked — no full text of the source

Clusterin is a risk factor for Alzheimer's disease.

“Clu, which is secreted separately from ApoE-containing lipoproteins but can be found together with ApoE in CSF lipoproteins, was also identified as a risk factor for AD in a genome wide association study [19, 103, 104].”

• cites [19] DeMattos RB, Brendza RP, Heuser JE, Kierson M, Cirrito JR, Fryer J, Sullivan PM, Fagan AM, Han X, Holtzman DM. Purification and characterization of astrocyte-secreted apolipoprotein E and J-containing lipoproteins from wild-type and human apoE transgenic mice. Neurochem Int. 2001;39:415–25. sourceNot checked — no full text of the source
• cites [103] Lambert JC, Heath S, Even G, Campion D, Sleegers K, Hiltunen M, Combarros O, Zelenika D, Bullido MJ, Tavernier B, et al. Genome-wide association study identifies variants at CLU and CR1 associated with Alzheimer’s disease. Nat Genet. 2009;41:1094–9. sourceNot checked yet
• cites [104] Harold D, Abraham R, Hollingworth P, Sims R, Gerrish A, Hamshere ML, Pahwa JS, Moskvina V, Dowzell K, Williams A, et al. Genome-wide association study identifies variants at CLU and PICALM associated with Alzheimer’s disease. Nat Genet. 2009;41:1088–93. sourceNot checked yet

Incubation of spherical ApoE with CETP results in the generation of larger spherical particles due to particle fusion.

“Incubation of spherical ApoE with CETP results in the generation of larger spherical particles due to particle fusion [78].”

• cites [78] Rye KA, Bright R, Psaltis M, Barter PJ. Regulation of reconstituted high density lipoprotein structure and remodeling by apolipoprotein E. J Lipid Res. 2006;47:1025–36. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

The degree and type of lipidation also impacts binding of ApoE to its receptors.

“The degree and type of lipidation also impacts binding of ApoE to its receptors.”

• cites [57] Peters-Libeu CA, Newhouse Y, Hatters DM, Weisgraber KH. Model of biologically active apolipoprotein E bound to dipalmitoylphosphatidylcholine. J Biol Chem. 2006;281:1073–9. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

VLDLR binds all ApoE isoforms with similar affinity.

“VLDLR binds all ApoE isoforms with similar affinity.”

• cites [66] Ruiz J, Kouiavskaia D, Migliorini M, Robinson S, Saenko EL, Gorlatova N, Li D, Lawrence D, Hyman BT, Weisgraber KH, Strickland DK. The apoE isoform binding properties of the VLDL receptor reveal marked differences from LRP and the LDL receptor. J Lipid Res. 2005;46:1721–31. sourceNot checked — no full text of the source

Larger lipoprotein particles are able to accommodate more ApoE protein per particle.

“This is primarily a stoichiometric effect whereby larger lipoprotein particles are able to accommodate more ApoE protein per particle (Table 1).”

Overexpression of the ApoE receptor LDLR in the brain decreases tau mediated neurodegeneration.

“Overexpression of the ApoE receptor LDLR in the brain decreases tau mediated neurodegeneration [90].”

• cites [90] Shi Y, Andhey PS, Ising C, Wang K, Snipes LL, Boyer K, Lawson S, Yamada K, Qin W, Manis M, et al. Overexpressing low-density lipoprotein receptor reduces tau-associated neurodegeneration in relation to apoE-linked mechanisms. Neuron. 2021;109:2413–e24262417. sourceNot checked yet

The impact of ApoE on tau-mediated neurodegeneration is likely strongly dependent on the lipidation status of ApoE.

“However, the impact of ApoE on tau mediated neurodegeneration is likely strongly dependent on the lipidation status of ApoE.”

The size of LpE also alters the binding avidity to its receptors.

“In addition to conformational changes that occur when ApoE is lipidated, the size of LpE also alters the binding avidity to its receptors.”

Several studies investigating known CETP polymorphisms have shown no impact on AD risk.

“Several studies investigating known CETP polymorphisms have shown no impact on AD risk [79, 80].”

• cites [79] Qureischie H, Heun R, Lutjohann D, Popp J, Jessen F, Ledschbor-Frahnert C, Thiele H, Maier W, Hentschel F, Kelemen P, Kolsch H. CETP polymorphisms influence cholesterol metabolism but not Alzheimer’s disease risk. Brain Res. 2008;1232:1–6. sourceNot checked — no full text of the source
• cites [80] Li Q, Huang P, He QC, Lin QZ, Wu J, Yin RX. Association between the CETP polymorphisms and the risk of Alzheimer’s disease, carotid atherosclerosis, longevity, and the efficacy of statin therapy. Neurobiol Aging. 2014;35:e15131513–1523. sourceNot checked — no full text of the source

LpE impact AD disease pathogenesis through association with Aβ and tau.

“LpE also impact AD disease pathogenesis through association with Aβ and tau.”

In vitro studies using ApoE isolated from human patients was lipidated with POPC and unesterified cholesterol mixed with LCAT revealed that cholesterol esterification resulted in spherical particles.

“In vitro studies using ApoE isolated from human patients was lipidated with POPC and unesterified cholesterol mixed with LCAT revealed that cholesterol esterification resulted in spherical particles [72].”

• cites [72] Gong EL, Nichols AV, Weisgraber KH, Forte TM, Shore VG, Blanche PJ. Discoidal complexes containing apolipoprotein E and their transformation by lecithin-cholesterol acyltransferase. Biochim Biophys Acta. 1989;1006:317–28. sourceNot checked — no full text of the source

Another study using ultracentrifugation isolation of LpE found very little association between monomeric Aβ and lipidated ApoE.

“However, another study using ultracentrifugation isolation of LpE found very little association between monomeric Aβ and lipidated ApoE [85].”

• cites [85] Verghese PB, Castellano JM, Garai K, Wang Y, Jiang H, Shah A, Bu G, Frieden C, Holtzman DM. ApoE influences amyloid-beta (Abeta) clearance despite minimal apoE/Abeta association in physiological conditions. Proc Natl Acad Sci U S A. 2013;110:E1807–1816. sourceNot checked yet

ApoE may mitigate tau-mediated neurodegeneration.

“Knockout of the complement component 3a receptor 1 (C3aR1) in PS19 mice, a model of tauopathy, results in attenuated inflammation and decreased neurodegeneration suggesting a potential role for ApoE to mitigate tau-mediated neurodegeneration.”

• AssumptionRests on an assumption: In PS19 tauopathy mice, C3aR1 knockout results in attenuated inflammation and decreased neurodegeneration.

Although LCAT plays a role in LpE maturation, knockout of LCAT has been reported to have minimal to no impact on Aβ pathology in a mouse model of amyloidosis.

“Although LCAT plays a role in LpE maturation, knockout of LCAT has been reported to have minimal to no impact on Aβ pathology in a mouse model of amyloidosis [74].”

• cites [74] Stukas S, Freeman L, Lee M, Wilkinson A, Ossoli A, Vaisman B, Demosky S, Chan J, Hirsch-Reinshagen V, Remaley AT, Wellington CL. LCAT deficiency does not impair amyloid metabolism in APP/PS1 mice. J Lipid Res. 2014;55:1721–9. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

When assessing AD risk associated with the ApoE4 allele, CETP polymorphisms such as the C-629 A and Taq1B polymorphisms are associated with decreased AD risk.

“However, when assessing AD risk associated with the ApoE4 allele, CETP polymorphisms such as the C-629 A and Taq1B polymorphisms are associated with decreased AD risk [80, 81].”

• cites [80] Li Q, Huang P, He QC, Lin QZ, Wu J, Yin RX. Association between the CETP polymorphisms and the risk of Alzheimer’s disease, carotid atherosclerosis, longevity, and the efficacy of statin therapy. Neurobiol Aging. 2014;35:e15131513–1523. sourceNot checked — no full text of the source
• cites [81] Rodriguez E, Mateo I, Infante J, Llorca J, Berciano J, Combarros O. Cholesteryl ester transfer protein (CETP) polymorphism modifies the Alzheimer’s disease risk associated with APOE epsilon4 allele. J Neurol. 2006;253:181–5. sourceNot checked — no full text of the source

LCAT activity has been reported to be significantly reduced in the CSF of AD patients compared to control patients.

“Furthermore, LCAT activity has been reported to be significantly reduced in the CSF of AD patients compared to control patients [76, 77].”

• cites [76] Demeester N, Castro G, Desrumaux C, De Geitere C, Fruchart JC, Santens P, Mulleners E, Engelborghs S, De Deyn PP, Vandekerckhove J, et al. Characterization and functional studies of lipoproteins, lipid transfer proteins, and lecithin:cholesterol acyltransferase in CSF of normal individuals and patients with Alzheimer’s disease. J Lipid Res. 2000;41:963–74. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

• cites [77] Turri M, Conti E, Pavanello C, Gastoldi F, Palumbo M, Bernini F, Aprea V, Re F, Barbiroli A, Emide D, et al. Plasma and cerebrospinal fluid cholesterol esterification is hampered in Alzheimer’s disease. Alzheimers Res Ther. 2023;15:95. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

When ApoE is secreted from astrocytes or recombinantly lipidated, ApoE adopts an antiparallel dimer on the surface of lipidated particles.

“When ApoE is secreted from astrocytes or recombinantly lipidated, ApoE adopts an antiparallel dimer of the surface of lipidated particles [17].”

• cites [17] Strickland MR, Rau MJ, Summers B, Basore K, Wulf J 2nd, Jiang H, Chen Y, Ulrich JD, Randolph GJ, Zhang R, et al. Apolipoprotein E secreted by astrocytes forms antiparallel dimers in discoidal lipoproteins. Neuron. 2024;112:1100–e11091105. sourceNot checked yet

Microglia secreted LpE is enriched in cholesterol esters relative to astrocyte ApoE.

“Microglia secreted LpE is enriched in cholesterol esters relative to astrocyte ApoE.”

ApoC1 inhibits binding of ApoE to LRP1 and LDLR.

“Apolipoprotein C1 (ApoC1) was found to be present at higher levels in ApoE2 and ApoE3 microglia secreted lipoproteins and is reported to inhibit binding of ApoE to LRP1 and LDLR [132].”

• cites [132] Sehayek E, Eisenberg S. Mechanisms of inhibition by apolipoprotein C of apolipoprotein E-dependent cellular metabolism of human triglyceride-rich lipoproteins through the low density lipoprotein receptor pathway. J Biol Chem. 1991;266:18259–67. sourceNot checked — no full text of the source

ApoE isoform impacts the interaction of ApoE with other apolipoproteins.

“ApoE isoform also impacts the interaction of ApoE with other apolipoproteins.”

ApoE isoform alters the proteome of microglial secreted LpE.

“ApoE isoform also alters the proteome of microglial secreted LpE.”

ApoE isoforms influence the lipid composition of LpE.

“ApoE isoforms have also been reported to influence the lipid composition of LpE.”

Microglia secreted ApoE is enriched with C1q, LPL, and C3.

“Microglia secreted ApoE is enriched with C1q, LPL, and C3.”

Lipidation of ApoE dramatically alters its function, determining its interaction with ApoE receptors and pathological proteins such as Aβ and tau.

“The lipidation of ApoE dramatically alters its function determining its interaction with ApoE receptors and pathological proteins such as Aβ and tau.”

ApoE, especially ApoE4, has pleiotropic effects on disease progression.

“This is especially important in understanding the pleiotropic effects of ApoE, especially ApoE4, on disease progression [146].”

• cites [146] Yassine HN, Hugo C, O’Donovan B, Stephens IO, Johnson LA, Cole G, Tcw J, Johansson J, Kisler K, Chiba-Falek O. APOE-targeted therapeutics for Alzheimer’s disease. J Neurosci. 2025;45. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

ApoC1 is present at higher levels in ApoE2 and ApoE3 microglia-secreted lipoproteins.

“Apolipoprotein C1 (ApoC1) was found to be present at higher levels in ApoE2 and ApoE3 microglia secreted lipoproteins and is reported to inhibit binding of ApoE to LRP1 and LDLR [132].”

• cites [132] Sehayek E, Eisenberg S. Mechanisms of inhibition by apolipoprotein C of apolipoprotein E-dependent cellular metabolism of human triglyceride-rich lipoproteins through the low density lipoprotein receptor pathway. J Biol Chem. 1991;266:18259–67. sourceNot checked — no full text of the source

In mouse astrocytes expressing human ApoE, ApoE directly associates with lipid droplets.

“In mouse astrocytes expressing human ApoE, ApoE has been reported to directly associate with lipid droplets [130].”

• cites [130] Windham IA, Powers AE, Ragusa JV, Wallace ED, Zanellati MC, Williams VH, Wagner CH, White KK, Cohen S. APOE traffics to astrocyte lipid droplets and modulates triglyceride saturation and droplet size. J Cell Biol. 2024;223. sourceNot checked yet

After loading astrocytes with oleic acid, ApoE4 lipoproteins contain more TAG-rich particles compared to ApoE2 and ApoE3 astrocytes.

“After loading astrocytes with oleic acid, the group also found that ApoE4 lipoproteins contained more TAG rich particles compared to ApoE2 and ApoE3 astrocytes [124].”

• cites [124] Lindner K, Beckenbauer K, van Ek LC, Titeca K, de Leeuw SM, Awwad K, Hanke F, Korepanova AV, Rybin V, van der Kam EL, et al. Isoform- and cell-state-specific lipidation of ApoE in astrocytes. Cell Rep. 2022;38:110435. sourceNot checked yet

Astrocyte ApoE is enriched in phosphatidylcholine compared to microglial ApoE.

“Astrocyte ApoE is enriched in phosphatidylcholine compared to microglial ApoE.”

LXR agonist treatment has a beneficial impact on both Aβ and tau pathology.

“This has been shown to have a beneficial impact on both Aβ and tau pathology; suggesting a potential therapeutic avenue for the treatment of AD and related tauopathies.”

ApoE secreted by different cell types and under conditions of lipid stress differs in lipid and protein composition.

“Complicating the picture even more are differences in the lipid and protein composition of ApoE secreted by different cell types and under conditions of lipid stress.”

ApoE isoform alters LpE lipid and protein content.

“ApoE isoform has also been reported to alter LpE lipid and protein content.”

ApoE4 causes dramatic lipid dysregulation in microglia under certain conditions, associated with altered lipid transport, accumulation of triglycerides and cholesterol esters, and accumulation of lipid droplets.

“ApoE4 is known to cause dramatic lipid dysregulation in microglia under certain conditions that is associated with altered lipid transport, accumulation of triglycerides and cholesterol esters, and accumulation of lipid droplets [127].”

• cites [127] Sprenger KG, Lietzke EE, Melchior JT, Bruce KD. Lipid and lipoprotein metabolism in microglia: Alzheimer’s disease mechanisms and interventions. J Lipid Res. 2025;66:100872. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

The ApoE-ApoA2 heterodimer has lower affinity to LDLR than ApoE alone.

“The ApoE-ApoA2 heterodimer has lower affinity to LDLR than ApoE alone [137].”

• cites [137] Borghini I, James RW, Blatter MC, Pometta D. Distribution of apolipoprotein E between free and A-II complexed forms in very-low- and high-density lipoproteins: functional implications. Biochim Biophys Acta. 1991;1083:139–46. sourceNot checked — no full text of the source

LXR agonist treatment suggests a potential therapeutic avenue for the treatment of Alzheimer's disease and related tauopathies.

“This has been shown to have a beneficial impact on both Aβ and tau pathology; suggesting a potential therapeutic avenue for the treatment of AD and related tauopathies.”

The ApoE-ApoA2 heterodimer has been isolated in human CSF samples.

“The ApoE-ApoA2 heterodimer has also been isolated in human CSF samples [63, 138].”

• cites [63] LaDu MJ, Gilligan SM, Lukens JR, Cabana VG, Reardon CA, Van Eldik LJ, Holtzman DM. Nascent astrocyte particles differ from lipoproteins in CSF. J Neurochem. 1998;70:2070–81. sourceNot checked — no full text of the source
• cites [138] Katsuyama T, Kondo Y, Hidaka E, Hidaka H, Tozuka M, Yamauchi K. Characterization of Apolipoprotein E-containing Lipoproteins in Cerebrospinal Fluid: Effect of Phenotype on the Distribution of Apolipoprotein E. Clin Chem. 1999;45:1431–8. sourceNot checked — no full text of the source

Pericytes secrete ApoE similar in size to astrocyte-secreted LpE but containing higher cholesterol levels than astrocyte-secreted ApoE.

“Pericytes have been shown to secrete ApoE similar in size to astrocyte secreted LpE but containing higher cholesterol levels than astrocyte secreted ApoE [112].”

• cites [112] Yamazaki Y, Shinohara M, Yamazaki A, Ren Y, Asmann YW, Kanekiyo T, Bu G. ApoE (Apolipoprotein E) in Brain Pericytes Regulates Endothelial Function in an Isoform-Dependent Manner by Modulating Basement Membrane Components. Arterioscler Thromb Vasc Biol. 2020;40:128–44. sourceNot checked yet

In human CSF, ApoC1 is significantly reduced in APOE ε4 carriers compared to APOE ε3/ε3 homozygotes.

“This result is mirrored in human CSF where ApoC1 was found to be significantly reduced in APOE ε4 carriers compared to ApoE ε3/ε3 homozygotes [133].”

• cites [133] Cudaback E, Li X, Yang Y, Yoo T, Montine KS, Craft S, Montine TJ, Keene CD. Apolipoprotein C-I is an APOE genotype-dependent suppressor of glial activation. J Neuroinflammation. 2012;9:192. sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

The disulfide linkage of ApoE3 on LpE reduces the affinity of ApoE3 lipoprotein for LDLR.

“The disulfide linkage of ApoE3 on LpE reduces the affinity for ApoE3 lipoprotein to LDLR [121].”

• cites [121] Weisgraber KH, Shinto LH. Identification of the disulfide-linked homodimer of apolipoprotein E3 in plasma. Impact on receptor binding activity. J Biol Chem. 1991;266:12029–34. sourceNot checked — no full text of the source