CoChat
Sign Up
Cited by 53Neuroinflammation and Neurodegeneration MechanismsAlzheimer's disease research and treatmentsInflammasome and immune disorders

The P522R protective variant of PLCG2 promotes the expression of antigen presentation genes by human microglia in an Alzheimer's disease mouse model

Open access
Claes, Christel, England, Whitney E., Danhash, Emma P., Kiani Shabestari, Sepideh, Jairaman, Amit, Chadarevian, Jean Paul, Hasselmann, Jonathan, Tsai, Andy P. +11 more·2022·Alzheimer's & Dementia
DOI 10.1002/alz.12577PMC PMC9360195
Open this paper in CoChat — free accountOpen PDF

Abstract

The P522R variant of PLCG2, expressed by microglia, is associated with reduced risk of Alzheimer's disease (AD). Yet, the impact of this protective mutation on microglial responses to AD pathology remains unknown. Chimeric AD and wild‐type mice were generated by transplanting PLCG2‐P522R or isogenic wild‐type human induced pluripotent stem cell microglia. At 7 months of age, single‐cell and bulk RNA sequencing, and histological analyses were performed. The PLCG2‐P522R variant induced a significant increase in microglial human leukocyte antigen (HLA) expression and the induction of antigen presentation, chemokine signaling, and T cell proliferation pathways. Examination of immune‐intact AD mice further demonstrated that the PLCG2‐P522R variant promotes the recruitment of CD8 + T cells to the brain. These data provide the first evidence that the PLCG2‐P522R variant increases the capacity of microglia to recruit T cells and present antigens, promoting a microglial transcriptional state that has recently been shown to be reduced in AD patient brains.

AI snapshot

Written from the paper’s full text.

TL;DR

In chimeric AD and WT mice carrying human iPSC-derived microglia, the AD-protective PLCG2-P522R variant increased HLA/MHC class II antigen-presentation gene expression and chemokine signaling, shifting microglia toward a cytokine/interferon-responsive state. In immune-intact P522R KI 5XFAD mice, the variant also increased CD8+ T cell recruitment to the brain without altering amyloid plaque burden in the chimeric model.

Key findings

  • P522R xenografted human microglia (xMGs) showed significantly increased HLA-DR protein around amyloid plaques, with no change in the number of xMGs within 10 μm of plaques (P = .37), total plaque load (P = .98), CD9 (P = .29), APOE, LAMP1, amyloid internalization, microglial morphology, or GFAP+ astrocyte reactivity.
  • scRNA-seq revealed six xMG clusters; P522R caused a significant reduction in homeostatic microglia (P = .011), an increase in cytokine-expressing microglia (P = .001), and a trend toward increased interferon-responsive microglia (P = .08). Increased genes included CCL2, CCL3, CCL8, CXCL10, IL1B; DAM genes MAFB, SPP1, FABP5; HLA genes HLA-DPB1, HLA-A, HLA-DRA, CD74, HLA-DPA1; and IFN genes IFI27, IFITM3, LY6E, IFIT3, MX1. Pseudotime suggested P522R xMGs transition toward DAM via an interferon-responsive path, whereas WT xMGs move via an MHC class II intermediate.
  • Bulk RNA-seq found 505 differentially expressed genes (log2 fold change > 1, FDR < 0.05), with upregulated CCL8, multiple HLA genes, and CIITA. Gene Ontology highlighted MHC class II antigen presentation, cytokine/chemokine signaling, interferon signaling, and regulation of T cell proliferation; molecular function analysis emphasized MHC class II protein binding and antigen binding. P522R xMG genes overlapped with a human microglial cluster (cluster 7) reduced in AD patient brains, and P522R xMGs significantly upregulated six of these antigen-presentation genes.
  • In immune-intact P522R KI 5XFAD mice, there was a significant increase in CD8+ T cells, but not CD4+ T cells, in the dorsal subiculum, with T cells often near microglia; no difference in total plaque load was observed (P = .26 for CD8 analysis; P = .36 for CD4 analysis).

Methods

  • Isogenic PLCG2 wild-type and homozygous PLCG2-P522R human iPSC lines were generated via CRISPR/Cas9, differentiated into hematopoietic progenitors and microglia, and confirmed to have a hypermorphic calcium-signaling effect (increased resting calcium and store-operated calcium entry). HPCs were transplanted into P2–P3 WT and 5XFAD chimeric mice (hCSF1/MITRG), 400K cells/pup at eight sites; xMGs matured for 7 months.
  • Human xMGs were isolated for scRNA-seq and bulk RNA-seq, with histology on half brains. scRNA-seq: n = 2 5X mice with WT xMGs, n = 1 5X mouse with P522R xMGs, n = 1 WT mouse with WT xMGs, n = 1 WT mouse with P522R xMGs. Bulk RNA-seq: n = 3 5X WT xMGs, n = 6 5X P522R xMGs; n = 3 WT WT xMGs, n = 7 WT P522R xMGs. Histology pooled n = 10 P522R xMG and n = 7 WT xMG AD chimeric mice; n = 7 each in WT chimeric mice. P522R KI 5XFAD mice were 7.5-month-old males, n = 8 per genotype.
  • Analyses included Seurat v3/SCTransform, PCA, clustering, UMAP, FindAllMarkers Wilcoxon tests, Monocle 3 pseudotime; bulk Kallisto/DESeq2, PANTHER GO, Cytoscape; Fluo-4/Fura-Red calcium imaging; Welch’s t-test and Mann-Whitney U-test.

Limitations

  • Stated: the chimeric AD mice are immunodeficient (Rag2–/–, il2rγ–/–) and lack T cells, which may explain why increased HLA expression did not produce detectable differences in AD pathology. Future studies are needed to determine whether the increased CD8+ T cells are cytotoxic or memory CD8+ T cells, whether the heightened T cell response is neuroprotective, and whether the protective allele produces similar responses in human subjects; post mortem microglia may be affected by agonal state or comorbidities.
  • Evident from the text: scRNA-seq used very small numbers, with some groups n = 1, limiting robustness of single-cell differential proportion analysis; all mouse experiments used male mice only; histological data were pooled across two chimeric mouse cohorts; T cell analyses in P522R KI 5XFAD mice were histological only, and T cells are relatively rare in brain.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1002/alz.12577

Cites

43 of 43 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

25 of 27 cited sources checked · 11 supported · 1 flagged · accuracy not yet measured

  • Premisecitation

    In vitro studies have demonstrated that the P522R variant induces a slight increase in cytosolic calcium, both basally and upon stimulation, indicating mild hypermorphic activity.

    “In vitro studies have demonstrated that the P522R variant induces a slight increase in cytosolic calcium, both basally and upon stimulation, indicating mild hypermorphic activity. 10 , 11 , 12”
    Quote in the paperNot a substantial claim3 of 3 sources checked
    • cites [10] Magno L, Lessard CB, Martins M, et al. Alzheimer's disease phospholipase C‐gamma‐2 (PLCG2) protective variant is a functional hypermorph. Alzheimers Res Ther. 2019; 11(1): 16. 30711010 PMC6359863 source

      The Results section reports a small increase in intracellular Ca2+ release for P522R versus wild-type PLCγ2 after EGF stimulation, and the Discussion describes a small hypermorphic effect. Figure 4’s caption mentions basal and stimulated PLC activity, but our copy does not report an increase in basal cytosolic calcium. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [11] Takalo M, Wittrahm R, Wefers B, et al. The Alzheimer's disease‐associated protective Plcgamma2‐P522R variant promotes immune functions. Mol Neurodegener. 2020; 15(1): 52. 32917267 PMC7488484 source

      The Findings section reports higher basal Ip1 levels in cultured P522R knock-in macrophages and interprets this as a mild hypermorphic effect on Plcγ2 enzyme activity. It does not report a measurement of cytosolic calcium, either basally or upon stimulation; the reported stimulated response concerns cytokine secretion. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [12] Maguire E, Menzies GE, Phillips T, et al. PIP2 depletion and altered endocytosis caused by expression of Alzheimer's disease‐protective variant PLCgamma2 R522. EMBO J. 2021; 40(17): e105603. 34254352 PMC8408593 source

      The Results section reports greater cytosolic Ca2+ responses after stimulation in R522-expressing macrophages and microglia, and the Discussion describes the variant as hyperfunctional. The passages do not report an increase in basal cytosolic calcium or establish that the increase was slight. Page numbers were not available in our copy. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • Premisecitation

    The P522R variant of PLCG2, expressed by microglia, is associated with reduced risk of late-onset Alzheimer's disease.

    “The P522R variant of PLCG2, expressed by microglia, is associated with reduced risk of Alzheimer's disease (AD).”
    • Also stated in: § NARRATIVE · plain
      “Recently, the PLCG2 missense variant Pro522Arg (P522R), predominantly expressed by microglia within the brain, was shown to be associated with a reduced risk of developing late‐onset AD. 6”
    • Also stated in: § RESEARCH IN CONTEXT · plain
      “Current literature describes the PLCG2 missense variant P522R, primarily expressed by microglia in the brain, is associated with a reduced risk of developing late‐onset Alzheimer's disease (AD).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [6] Sims R, Van Der Lee SJ, Naj AC, et al. Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial‐mediated innate immunity in Alzheimer's disease. Nat Genet. 2017; 49(9): 1373‐ 1384. 28714976 PMC5669039 source
  • Premisecitation

    A similar subset of MHC class II HLA genes was recently shown to be reduced in microglia from human AD brains.

    “Interestingly, a similar subset of MHC class II HLA genes was recently shown to be reduced in microglia from human AD brains. 18”
    • Also stated in: § CONSOLIDATED RESULTS AND STUDY DESIGN · plain
      “a recent study in AD patient and control brains revealed a substantial reduction of the microglial cluster expressing MHC class II antigen presentation‐associated genes in AD patient brains. 18”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [18] Olah M, Menon V, Habib N, et al. Single cell RNA sequencing of human microglia uncovers a subset associated with Alzheimer's disease. Nat Commun. 2020; 11(1): 6129. 33257666 PMC7704703 source

      The Results (Assessing the relation of IBA1+CD74high cells to AD; page unavailable) report that an antigen-presenting microglial subset is less frequent in AD frontal cortex, while its defining gene set is downregulated in AD cortex. The paper does not establish that a specified subset of MHC class II HLA genes is reduced within microglia from AD brains; its measured reduction in microglia is in the frequency of cluster 7 cells. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • Premisecitation

    In vivo studies of the P522R variant have been limited to wild-type (non-AD) P522R knock-in mice, which reported a trend toward increased expression of Cst7, Tyrobp, Clec7a, and Ccl3 by quantitative polymerase chain reaction of total brain mRNA.

    “Despite this recent progress, studies of the P522R variant in vivo have thus far remained limited to the examination of wild‐type (non‐AD) P522R knock‐in (KI) mice, which reported a trend toward increased expression of Cst7, Tyrobp, Clec7a, and Ccl3 by quantitative polymerase chain reaction of total brain mRNA. 11 , 12”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [11] Takalo M, Wittrahm R, Wefers B, et al. The Alzheimer's disease‐associated protective Plcgamma2‐P522R variant promotes immune functions. Mol Neurodegener. 2020; 15(1): 52. 32917267 PMC7488484 source
    • cites [12] Maguire E, Menzies GE, Phillips T, et al. PIP2 depletion and altered endocytosis caused by expression of Alzheimer's disease‐protective variant PLCgamma2 R522. EMBO J. 2021; 40(17): e105603. 34254352 PMC8408593 source

      Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured
  • Premisecitation

    5XFAD mice that lack MHC class II expression exhibit increased amyloid pathology.

    “a recent study found that 5XFAD mice that lack MHC class II expression exhibit increased amyloid pathology, 21”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [21] Mittal K, Eremenko E, Berner O, et al. CD4 T cells induce a subset of MHCII‐Expressing microglia that attenuates Alzheimer's pathology. iScience. 2019; 16: 298‐ 311. 31203186 PMC6581663 source
  • Classified as probably not a substantial claim. 15
  • May combine two claims. 23
  • The quote only partly states this claim. 1

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The P522R variant moderately increases store-operated calcium entry (SOCE) in HEK293T cells.

    “In addition, depletion of intracellular calcium stores activates a calcium flux across the plasma membrane, referred to as store‐operated calcium entry (SOCE), which is also moderately increased by the P522R variant in HEK293T cells. 10”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [10] Magno L, Lessard CB, Martins M, et al. Alzheimer's disease phospholipase C‐gamma‐2 (PLCG2) protective variant is a functional hypermorph. Alzheimers Res Ther. 2019; 11(1): 16. 30711010 PMC6359863 source

      The Results section distinguishes a small increase in intracellular Ca2+ release from store-operated Ca2+ entry. It reports no significant difference in extracellular Ca2+ entry between HEK293T cells expressing wild-type PLCγ2 and those expressing P522R. Page numbers are not provided in our copy. (LLM, conf=0.93)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    PLCG2 is a downstream component of TREM2 signaling, an important microglial AD risk gene.

    “PLCG2 has also been shown to be a downstream component of TREM2 signaling, an important microglial AD risk gene. 7 , 8”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [7] Guerreiro R, Wojtas A, Bras J, et al. TREM2 variants in Alzheimer's disease. N Engl J Med. 2013; 368(2): 117‐ 127. 23150934 PMC3631573 source

      The Discussion identifies TREM2 as a signaling receptor and reports that rare TREM2 variants increase Alzheimer’s disease risk; the Results locate TREM2 in microglia around amyloid plaques. But the paper does not identify PLCG2 as a downstream component of TREM2 signaling; its Discussion names TYROBP as a component of the receptor-signaling complex. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [8] Jonsson T, Stefansson H, Steinberg S, et al. Variant of TREM2 associated with the risk of Alzheimer's disease. N Engl J Med. 2013; 368(2): 107‐ 116. 23150908 PMC3677583 source

      The Results identify a TREM2 variant associated with Alzheimer’s disease, and the Discussion says TREM2 is primarily expressed on microglia in the brain. The Discussion describes DAP12 in TREM2 signaling but does not identify PLCG2 as a downstream component. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    The P522R-associated calcium changes are associated with improved survival, enhanced phagocytic/endocytic activity, and increased acute inflammatory response.

    “Collectively, these changes are associated with improved survival, enhanced phagocytic/endocytic activity, and increased acute inflammatory response. 11 , 12”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [11] Takalo M, Wittrahm R, Wefers B, et al. The Alzheimer's disease‐associated protective Plcgamma2‐P522R variant promotes immune functions. Mol Neurodegener. 2020; 15(1): 52. 32917267 PMC7488484 source

      The Findings section reports improved survival in P522R knock-in macrophages after growth-factor withdrawal, a stronger acute cytokine response to stimulation, and enhanced phagocytic activity in BV2 cells expressing P522R. The increase in phagocytosis in knock-in macrophages was not statistically significant. The paper measures increased Ip1 signaling, but does not establish that calcium changes produced these outcomes or separately demonstrate enhanced endocytic activity (Findings; no page given). (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [12] Maguire E, Menzies GE, Phillips T, et al. PIP2 depletion and altered endocytosis caused by expression of Alzheimer's disease‐protective variant PLCgamma2 R522. EMBO J. 2021; 40(17): e105603. 34254352 PMC8408593 source

      The Results section reports enhanced calcium responses and endocytic clearance with R522, but significantly reduced—not enhanced—phagocytosis in the tested cells (page unavailable). The Discussion says an enhanced inflammatory response requires further investigation, and our copy does not establish improved survival. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    The chimeric transplantation approach has been validated in prior work.

    “For further details and validation of this chimeric approach please see Hasselmann et al. 14”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [14] Hasselmann J, Coburn MA, England W. Development of a chimeric model to study and manipulate human microglia in vivo. Neuron. 2019; 103(6): 1016‐ 1033.e10. e10. 31375314 PMC7138101 source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    CIITA acts as a master regulator for the expression of MHC class II genes and is also capable of inducing MHC class I genes.

    “which acts as a master regulator for the expression of MHC class II genes and is also capable of inducing MHC class I genes. 15 , 16”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [15] Devaiah BN, Singer DS. CIITA and its dual roles in MHC gene transcription. Front Immunol. 2013; 4: 476. 24391648 PMC3868913 source
    • cites [16] Martin BK, Chin K‐C, Olsen JC, et al. Induction of MHC class I expression by the MHC class II transactivator CIITA. Immunity. 1997; 6(5): 591‐ 600. 9175837 source

  • May combine two claims.

    Premisecitation

    MITRG and hCSF1 mice enable equivalent engraftment and survival of human iPSC-derived microglia, as the presence of the humanized CSF1 allele is necessary whereas inclusion of the CSF2 and TPO alleles are dispensable.

    “We recently confirmed that MITRG and hCSF1 mice enable equivalent engraftment and survival of human iPSC‐derived microglia as the presence of the humanized CSF1 allele is necessary whereas inclusion of the CSF2 and TPO alleles are dispensable. 14”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [14] Hasselmann J, Coburn MA, England W. Development of a chimeric model to study and manipulate human microglia in vivo. Neuron. 2019; 103(6): 1016‐ 1033.e10. e10. 31375314 PMC7138101 source

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Interferon gamma (IFN-γ) from memory CD8+ T cells upregulates MHC class II in microglia and keeps them in an activated state.

    “and interferon gamma (IFN‐y) from memory CD8+ T cells upregulates MHC class II in microglia and keeps them in an activated state. 25”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [25] Mutnal MB, Hu S, Little MR, Lokensgard JR. Memory T cells persisting in the brain following MCMV infection induce long‐term microglial activation via interferon‐gamma. J Neurovirol. 2011; 17(5): 424‐ 437. 21800103 PMC3204167 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    HLA-DRB polymorphisms are associated with increased risk of AD.

    “Moreover, HLA‐DRB polymorphisms are associated with increased risk of AD 2 , 19 , 20”
    Quote in the paperNot a substantial claim2 of 3 sources checked
    • cites [2] Karch CM, Goate AM. Alzheimer's disease risk genes and mechanisms of disease pathogenesis. Biol Psychiatry. 2015; 77(1): 43‐ 51. 24951455 PMC4234692 source
    • cites [19] Lu R‐C, Yang Wu, Tan L, et al. Association of HLA‐DRB1 polymorphism with Alzheimer's disease: a replication and meta‐analysis. Oncotarget. 2017; 8(54): 93219‐ 93226. 29190991 PMC5696257 source

      The Discussion reports that the C allele of HLA-DRB1 rs9271192 is associated with increased risk of late-onset AD in a Northern Han Chinese population; the Abstract also reports a supporting meta-analysis. The cited paper supports that specific variant and disease subtype, not the broader claim about HLA-DRB polymorphisms generally. Page numbers are not provided in our copy. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [20] Lambert J‐C, Ibrahim‐Verbaas CA, Harold D, et al. Meta‐analysis of 74,046 individuals identifies 11 new susceptibility loci for Alzheimer's disease. Nat Genet. 2013; 45(12): 1452‐ 1458. 24162737 PMC3896259 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    CIITA (class II trans-activator) is a master regulator of the expression of HLA genes, which encode the MHC class I and II protein complex.

    “CIITA (class II trans‐activator) is a master regulator of the expression of HLA genes which encode the MHC class I and II protein complex. 15 , 16”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [15] Devaiah BN, Singer DS. CIITA and its dual roles in MHC gene transcription. Front Immunol. 2013; 4: 476. 24391648 PMC3868913 source
    • cites [16] Martin BK, Chin K‐C, Olsen JC, et al. Induction of MHC class I expression by the MHC class II transactivator CIITA. Immunity. 1997; 6(5): 591‐ 600. 9175837 source

      The Discussion (p. 6) describes CIITA as a global regulator of the MHC class II antigen-presentation pathway and reports that it can induce MHC class I heavy-chain expression in certain cell lines. But the Discussion (p. 8) says its effect on class I expression may be cell-specific, so calling it a master regulator of both class I and II HLA gene expression overstates the paper's conclusion. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Interpretationown data

    Our data indicate that many of the genes enriched in P522R xMGs overlap with those in the human AD cluster 7 and are essential for antigen presentation.

    “our data indicate that many of the genes enriched in P522R xMGs overlap with those in the human AD cluster 7 and are essential for antigen presentation 18”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [18] Olah M, Menon V, Habib N, et al. Single cell RNA sequencing of human microglia uncovers a subset associated with Alzheimer's disease. Nat Commun. 2020; 11(1): 6129. 33257666 PMC7704703 source

      The Results (‘Annotating the clusters of human microglia’) identify cluster 7 as enriched in antigen-presentation genes, and the Discussion links it to Alzheimer’s disease. The paper does not establish that those genes are essential for antigen presentation. The overlap with P522R xMGs is presented as the citing authors’ own finding, not a result attributed to this source. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim.

    Premisecitation

    A recent study identified nine microglial subtypes in AD and control patient brains.

    “a recent study identified nine microglial subtypes in AD and control patient brains. 18”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [18] Olah M, Menon V, Habib N, et al. Single cell RNA sequencing of human microglia uncovers a subset associated with Alzheimer's disease. Nat Commun. 2020; 11(1): 6129. 33257666 PMC7704703 source

      The Introduction reports a catalog of nine human microglial subpopulations, so the number and identification are supported. But the Results section on the single-cell data identifies the discovery samples as AD and mild-cognitive-impairment autopsies plus epilepsy surgical samples, not AD and control brains; the later AD–control analysis mapped nuclei to the clusters but found none assigned to cluster 9. (LLM, conf=0.87)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    One microglial cluster (cluster 7) is characterized by expression of CD74 and many other MHC class II antigen presentation-associated genes and was shown to be substantially reduced in AD patients.

    “Of these, one cluster in particular (cluster 7) is characterized by the expression of CD74 and many other MHC class II antigen presentation‐associated genes and was shown to be substantially reduced in AD patients. 18”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [18] Olah M, Menon V, Habib N, et al. Single cell RNA sequencing of human microglia uncovers a subset associated with Alzheimer's disease. Nat Commun. 2020; 11(1): 6129. 33257666 PMC7704703 source

  • May combine two claims.

    Findingown data

    Gene Ontology analysis confirmed strong induction of MHC class II and antigen presentation pathways, cytokine and chemokine signaling, cell cycle regulation, interferon responsive pathways, and regulation of T cell proliferation and other immune effector signals.

    “This analysis confirmed the strong induction of MHC class II and antigen presentation pathways, cytokine and chemokine signaling, cell cycle regulation, interferon responsive pathways, and the regulation of T cell proliferation and other immune effector signals.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    No increase in the number of reactive GFAP+ astrocytes near P522R versus WT xMGs or amyloid plaques, nor an increase in GFAP protein expression, was observed.

    “In addition, we observed no increase in the number of reactive GFAP+ astrocytes near P522R versus WT xMGs or amyloid plaques, nor an increase in GFAP protein expression.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Gene Ontology analysis of upregulated genes revealed MHC class II antigen presentation as a predominant signal, along with cytokine/chemokine signaling, interferon signaling, and regulation of T cell proliferation.

    “Gene Ontology analysis of upregulated genes revealed MHC class II antigen presentation as a predominant signal, along with cytokine/chemokine signaling, interferon signaling, and regulation of T cell proliferation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    Introduction of the P522R mutation produces a hypermorphic effect on calcium signaling, significantly increasing resting calcium levels and store-operated calcium entry.

    “Upon confirmation that introduction of the P522R mutation produces a hypermorphic effect on calcium signaling, significantly increasing resting calcium levels and store‐operated calcium entry, we transplanted HPCs”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The PLCG2-P522R variant induced antigen presentation, chemokine signaling, and T cell proliferation pathways.

    “and the induction of antigen presentation, chemokine signaling, and T cell proliferation pathways.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    xMGs migrate throughout the left hippocampus (in which they were injected) but not the right hippocampus (which received a PBS control injection).

    “xMGs were shown to migrate throughout the left hippocampus (in which they were injected), but not the right hippocampus (which received a PBS control injection).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    xMGs were found surrounding plaques ipsilateral to the injection site.

    “xMGs were found surrounding plaques ipsilateral to the injection site”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    P522R xMGs significantly upregulate six genes that are essential for antigen presentation and are among those enriched in the human AD cluster 7.

    “P522R xMGs significantly upregulate six of these genes (*) that are essential for antigen presentation (D)”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims. The quote only partly states this claim.

    Study design and conductnone given

    All animal procedures were conducted in accordance with National Institutes of Health guidelines and approved by the University of California, Irvine Institutional Animal Care and Use Committee.

    “All animal procedures were conducted in accordance with National Institutes of Health guidelines and the University of California, Irvine Institutional Animal Care and Use Committee.”
    • Also stated in: § Detailed methods · plain
      “all experimental procedures were approved by the Institutional Animal Care and Use Committee (IACUC).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductown data

    Xenografted human iPSC-derived microglia (xMGs) matured and remained within recipient brains for 7 months.

    “xenografted human iPSC‐derived microglia (xMGs) matured and remained within recipient brains for 7 months, until they were isolated for single‐cell (scRNA‐seq) and bulk RNA sequencing.”
    • Also stated in: § CONSOLIDATED RESULTS AND STUDY DESIGN · plain
      “Xenografted human iPSC‐derived microglia (xMGs) matured and remained within male recipient brains for 7 months, until they were isolated for scRNA‐seq and bulk RNA sequencing, and half brains were used for histological analyses.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Images were taken with identical laser and detection settings between genotypes.

    “Images represent confocal Z‐stack (five images per mouse) taken within the retrosplenial granular cortex and piriform cortex at 40x magnification with identical laser and detection settings between genotypes.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    These data provide the first evidence that the PLCG2-P522R variant increases the capacity of microglia to recruit T cells and present antigens, promoting a microglial transcriptional state that has recently been shown to be reduced in AD patient brains.

    “These data provide the first evidence that the PLCG2‐P522R variant increases the capacity of microglia to recruit T cells and present antigens, promoting a microglial transcriptional state that has recently been shown to be reduced in AD patient brains.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    CD8+ T cells are elevated in human AD brains and can be found closely localized to microglia.

    “Interestingly, CD8+ T cells are also elevated in human AD brains, can be found closely localized to microglia, 24”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [24] Rogers J, Luber‐Narod J, Styren SD, Civin WH. Expression of immune system‐associated antigens by cells of the human central nervous system: relationship to the pathology of Alzheimer's disease. Neurobiol Aging. 1988; 9(4): 339‐ 349. 3263583 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    iPSC lines were used under approved human Stem Cell Research Oversight (hSCRO) committee protocols.

    “iPSC lines were used under approved human Stem Cell Research Oversight (hSCRO) committee protocols.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    The PLCG2-P522R variant increases HLA-DR expression by plaque-associated xMGs without altering the proximity of microglia to plaques.

    “Overall, these results indicate the PLCG2‐P522R variant increases HLA‐DR expression by plaque‐associated xMGs, without altering the proximity of microglia to plaques.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductown data

    Altered genes remained consistent between single-cell and bulk RNA sequencing and strengthened the single-cell observations.

    “As expected, altered genes remained consistent between single‐cell and bulk RNA seq and strengthened our single‐cell observations.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    There was negligible bleed-through of RFP into the red (Fura-Red) channel with the 488 nm laser.

    “There was negligible bleed‐through of RFP into the red (Fura‐Red) channel with the 488 nm laser.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Immunohistological analyses of P522R versus WT xMGs showed similar trends in both mouse cohorts, so histological data was pooled.

    “As expected, immunohistological analyses of P522R versus WT xMGs showed similar trends in both mouse cohorts; thus, histological data was pooled.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    The current findings strongly implicate increased microglia-T cell crosstalk, providing the first clues about the protective nature of the P522R variant.

    “However, the current findings strongly implicate increased microglia–T cell crosstalk, providing the first clues about the protective nature of the P522R variant.”
    • Also stated in: § CONSOLIDATED RESULTS AND STUDY DESIGN · boosted
      “Altogether, the current findings strongly implicate increased microglia–T cell crosstalk, providing the first clues about the protective nature of the P522R variant”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Immunofluorescent sections were visualized and captured by a blinded observer.

    “Immunofluorescent sections were visualized and captured by a blinded observer using an Olympus FV3000RS confocal microscope.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductreasoning

    The mouse model used for xMG engraftment is genetically immunodeficient (Rag2-/-, il2rγ-/-), which precludes examination of T cells in this model.

    “our mouse model is genetically immunodeficient (Rag2–/–, il2rγ–/–), thereby precluding the examination of T cells in this model”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    The P522R variant increases the expression of genes important for antigen presentation, which are conversely downregulated in human AD microglia.

    “Altogether, our data demonstrate that the P522R variant increases the expression of genes important for antigen presentation, which are conversely downregulated in human AD microglia.”
    Quote in the paperSubstantial claim
34 of 34

  • The paper relies on this without support.

    The impact of PLCG2-P522R on human microglial function in vivo and the mechanisms by which this variant reduces AD risk remain largely unknown.

    “Yet, the impact of this protective mutation on microglial responses to AD pathology remains unknown.”
    “However, the impact of PLCG2‐P522R on human microglial function in vivo and the mechanisms by which this variant reduces AD risk remains largely unknown.”

  • The paper relies on this without support.

    The P522R variant of PLCG2 is protective against Alzheimer's disease.

    “The protective P522R variant of PLCG2 increases HLA‐DR expression in plaque‐associated xMGs in chimeric AD mice but has no effect on microglial plaque proximity”
2 of 2

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The mildly hypermorphic PLCG2P522R variant is associated with increased longevity, improved clearance of Aβ, and protection against AD.

    “With respect to AD, the mildly hypermorphic PLCG2P522R variant is associated with increased longevity, improved clearance of Aβ, and protection against AD.”

    From PLCG2 modulates TREM2 expression and signaling in response to Alzheimer's disease pathology (2025) · cites this paper as [22]

    The Narrative (page unavailable) describes P522R as mildly hypermorphic and associated with reduced risk of late-onset AD. It does not establish increased longevity: its reference to improved survival concerns cellular effects, not lifespan. The Detailed results (page unavailable) found no significant increase in amyloid internalization or reduction in plaque burden in the chimeric AD mice, so improved Aβ clearance is not supported. (LLM, conf=0.90)

    Experimental — accuracy not yet measured

  • Recent genetic studies have revealed genetic variants in PLCG2 that divergently impact AD risk.

    “recent genetic studies have revealed genetic variants in PLCG2 that divergently impact AD risk. 11 , 22 , 23 , 24 , 25 , 26 , 27 , 29”

    From PLCG2 modulates TREM2 expression and signaling in response to Alzheimer's disease pathology (2025) · cites this paper as [22]

    The Narrative reports that the PLCG2 P522R variant is associated with reduced risk of late-onset AD. It does not identify another PLCG2 variant with a different effect on AD risk, so it supports the protective-variant part but not the claim of divergent effects across variants. (LLM, conf=0.85)

    Experimental — accuracy not yet measured

  • The GOF P522R variant of PLCG2 confers protection in AD and the M28L variant confers risk.

    “the GOF P522R variant of PLCG2 confers protection in AD and the M28L variant confers risk”

    From PLCG2 modulates TREM2 expression and signaling in response to Alzheimer's disease pathology (2025) · cites this paper as [22]

    The Narrative states that P522R is associated with reduced risk of late-onset AD, and the Research in Context section describes its hypermorphic enzyme activity, supporting the protective gain-of-function portion. No passage found for M28L states that it confers AD risk; that portion of the claim is unsupported by our copy. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • PLCG2 was believed to be almost exclusively expressed in microglia and has been extensively investigated in this cell type.

    “this AD risk gene was believed to be almost exclusively expressed in microglia and, as a consequence, it has been extensively investigated in this cell type18–21.”

    From PLCG2 downregulation impairs synaptic function and increases Alzheimer’s disease hallmarks in neuronal cultures (2026) · cites this paper as [19]

    The Research in Context section (page unavailable) describes the P522R variant as primarily expressed by microglia in the brain and cites studies in cultured microglia and mice. That supports a microglial research focus, but not the stronger, unqualified claim that PLCG2 is almost exclusively expressed in microglia. The Narrative section also says in vivo studies of the variant had remained limited. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • Missense hypermorphic variants of PLCG2 confer a reduced risk for Alzheimer's disease.

    “While missense hypermorphic variants of PLCG2 confer a reduced risk for AD, the mechanistic role that PLCγ2 plays in AD pathogenesis is unclear [44–48].”

    From Microglial function, INPP5D/SHIP1 signaling, and NLRP3 inflammasome activation: implications for Alzheimer’s disease (2023) · cites this paper as [45]

    The Research in Context section says the PLCG2 missense variant P522R is associated with reduced risk of late-onset AD and has a hypermorphic effect on enzyme activity. The source supports this for P522R, but does not establish the claim for multiple variants or show that the variant causes the reduction in risk. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Conflicting identifiers for the parent iPSC line

    Minor

    The methods identify the purchased RFP-expressing iPSC line as AICS‐0031‐035, but then identify the RFP line used to create the isogenic P522R line as AICS‐0035. These are different line identifiers, leaving the parent line unclear.

1 of 1

Cites

Flagged first, then by citations

1 of the 44 references couldn’t be matched to a known paper.

Cited by

Sorted by citations

Related

Authors
Claes, C., England, W. E., Danhash, E. P., Kiani Shabestari, S., Jairaman, A., Chadarevian, J. P., Hasselmann, J., Tsai, A. P., Coburn, M. A., Sanchez, J., Lim, T. E., Hidalgo, J. L. S., Tu, C., Cahalan, M. D., Lamb, B. T., Landreth, G. E., Spitale, R. C., Blurton‐Jones, M., & Davtyan, H.
Affiliations
  • University of California, Irvine (US)
  • Sue and Bill Gross Stem Cell Research Center University of California Irvine Irvine California USA
  • Indiana University School of Medicine
  • Institute for Memory Impairments and Neurological Disorders University of California Irvine Irvine California USA
Corresponding author
Claes, Christel
ORCID
Venue
Alzheimer's & Dementia
Publisher
Wiley
Published
2022-02-09
Volume
18
Issue
10
Pages
1765-1778
ISSN
  • 1552-5260 (ISSN-L)
  • 1552-5279
DOI
10.1002/alz.12577
PMC
PMC9360195
OpenAlex
W4211038984
Semantic Scholar
bf9c9bce46fb13623888dd404c84f66460ee09c9
Cited by
52
References
44
Citations by year
2026: 7 · 2025: 15 · 2024: 12 · 2023: 11 · 2022: 7
FWCI
3.19
Type
journal article
Language
en
Open access
Licence
Locations
  • Alzheimer s & Dementia (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • PubMed Central (submittedVersion, cc-by-nc-nd)
  • eScholarship (California Digital Library) (submittedVersion, cc-by-nc-nd)
  • IUScholarWorks (Indiana University) (submittedVersion, cc-by-nc-nd)
Funders
National Institutes of Health (AG048099, AG055524, AG056303, DA048813, AG061895, AG016573, AG054345, AG074566)
Topics
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Inflammasome and immune disorders
Keywords
PLCγ2
MeSH terms
Alzheimer Disease, Animals, Disease Models, Animal, Humans, Mice, Transgenic, Amyloid beta-Peptides, Microglia, Antigen Presentation, CD8-Positive T-Lymphocytes, Chemokines, Mice, Phospholipase C gamma, Induced Pluripotent Stem Cells

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-18.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-18.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review