Reactive astrocyte nomenclature, definitions, and future directions

In the paper

“Expression of GFAP is also modulated by physiological stimuli such as physical activity19, exposure to enriched environments19, and glucocorticoids20, and it fluctuates with circadian rhythms in the suprachiasmatic nucleus21.”

What the sources say

• Partly supported

  The paper reports that voluntary running and enriched environments increased the surface area and volume of GFAP-positive astrocyte profiles in the hippocampus of mice (main text; page not provided). It does not establish that GFAP expression itself changed. The glucocorticoid and circadian-rhythm clauses are attached to other citations, not this source. (LLM, conf=0.84)

  cites [19] Rodríguez, J. J., Terzieva, S., Olabarria, M., Lanza, R. G. & Verkhratsky, A. Enriched environment and physical activity reverse astrogliodegeneration in the hippocampus of AD transgenic mice. Cell Death Dis 4, e678 (2013). sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites [20] O’Callaghan, J. P., Brinton, R. E. & McEwen, B. S. Glucocorticoids regulate the synthesis of glial fibrillary acidic protein in intact and adrenalectomized rats but do not affect its expression following brain injury. J. Neurochem. 57, 860–869 (1991). source
• ?Not checked — no full text of the sourcecites [21] Gerics, B., Szalay, F. & Hajós, F. Glial fibrillary acidic protein immunoreactivity in the rat suprachiasmatic nucleus: circadian changes and their seasonal dependence. J. Anat. 209, 231–237 (2006). Early demonstration that GFAP is regulated in a physiological context. source

In the paper

“However, while the degree of GFAP upregulation in reactive astrocytes often parallels the severity of the injury6, this correlation is not always proportional, perhaps due to regional differences of astrocytes, including basal GFAP content13,14.”

What the sources say

• ?Could not verify

  The passages available from our copy are repository metadata and navigation text, not the paper’s discussion; they have no section or page labels. Searches for GFAP upregulation, injury severity, regional differences, and basal GFAP content returned no passage addressing the claim, so it cannot be assessed from this copy. (LLM, conf=0.72)

  cites [6] Escartin, C., Guillemaud, O. & Carrillo-de Sauvage, M. A. Questions and (some) answers on reactive astrocytes. Glia 67, 2221–2247 (2019). sourceExperimental — accuracy not yet measured
• Supported

  Citation 13/14 is attached to the proposed regional differences in astrocytes, including baseline GFAP, rather than to the injury-severity finding cited to reference 6. The Discussion (page unavailable) says GFAP is rarely expressed in thalamic astrocytes, supporting regional variation in GFAP expression. This paper does not establish that such variation explains a nonproportional injury response, but the citing sentence presents that explanation as a possibility. (LLM, conf=0.87)

  cites [13] Griemsmann, S. et al. Characterization of panglial gap junction networks in the thalamus, neocortex, and hippocampus reveals a unique population of glial cells. Cereb. Cortex 25, 3420–3433 (2015). source
• ?Not checked — no full text of the sourcecites [14] Ben Haim, L. & Rowitch, D. H. Functional diversity of astrocytes in neural circuit regulation. Nat. Rev. Neurosci. 18, 31–41 (2017). source

In the paper

“Further, dye-filling methods can be used to visualize whole astrocytes in mice23, as well as in human brain samples from surgical resections (Fig. 1b)24.”

What the sources say

• Supported

  The Abstract says the authors used dye-filling to reveal the full three-dimensional shape of astrocytes in mice, and the Methods describe injecting dye into astrocytes in mouse brain slices. In the citing sentence, this source is attached to the mice claim (reference 23); the human surgical-sample claim has a separate citation (reference 24). (LLM, conf=0.93)

  cites [23] Wilhelmsson, U. et al. Redefining the concept of reactive astrocytes as cells that remain within their unique domains upon reaction to injury. Proc. Natl Acad. Sci. USA 103, 17513–17518 (2006). The complete visualization of astrocytes using whole-cell filling techniques revealed that reactive astrocytes display subtle morphological changes and remain in their 3D territorial domain, highlighting that GFAP immunostaining overestimates the true degree of astrocyte hypertrophy. source
• Supported

  The methods section (page not available) describes whole-cell recordings in freshly resected human brain slices. It says fluorescent dyes were added to assess cell morphology, with Alexa Fluor 594 allowing the shape of the patched cell to be evaluated. This supports the human-sample portion attached to citation 24; the mouse portion is attached to citation 23. (LLM, conf=0.88)

  cites [24] Sosunov, A. A. et al. Phenotypic heterogeneity and plasticity of isocortical and hippocampal astrocytes in the human brain. J. Neurosci. 34, 2285–2298 (2014). source

In the paper

“GFAP is also expressed by progenitor cells15 and its expression depends on developmental stages16,17.”

What the sources say

• Supported

  In “Transformation of Neuroepithelial Cells and the Origin of Radial Glia” (page unavailable), the review describes GFAP expression in some radial glial cells, which serve as neural precursors. It also says the GFAP promoter is expressed by radial glia at a later stage and may become active in the mouse ventral telencephalon only later in development, supporting the developmental-stage qualification. (LLM, conf=0.88)

  cites [15] Kriegstein, A. & Alvarez-Buylla, A. The glial nature of embryonic and adult neural stem cells. Annu. Rev. Neurosci. 32, 149–184 (2009). source
• ?Could not verify

  The citation to this paper is attached to the developmental-stage part of the sentence, not the progenitor-cell part. The section on gene expression changes during astrocyte and oligodendrocyte development compares developmental stages, and the Aldh1L1 marker section discusses GFAP, but neither passage says that GFAP expression changes with developmental stage. Searches for GFAP at P1, P7, and P17 found no decisive passage. (LLM, conf=0.70)

  cites [16] Cahoy, J. D. et al. A transcriptome database for astrocytes, neurons, and oligodendrocytes: a new resource for understanding brain development and function. J. Neurosci. 28, 264–278 (2008). This study represented a technical and conceptual breakthrough in the neurosciences as the first unbiased classification of brain cell populations based on transcriptomic profiles using early microarray analyses. The resulting transcriptomes are a powerful tool to gain insight into novel brain cell functions. More recently, the classification of brain cells has been further refined and enriched by sc/snRNAs sourceExperimental — accuracy not yet measured
• Supported

  The Introduction describes GFAP as appearing during an early, mainly embryonic phase of astrocyte development and being downregulated during later maturation, though it persists in white-matter astrocytes. This supports the developmental-stage portion of the sentence, to which citations 16 and 17 are attached; the progenitor-cell portion is separately attributed to citation 15. No page number is available in our copy. (LLM, conf=0.93)

  cites [17] Roybon, L. et al. Human stem cell-derived spinal cord astrocytes with defined mature or reactive phenotypes. Cell Rep 4, 1035–1048 (2013). source

In the paper

“Thorough visualization is necessary because astrocytes undergo distinct morphological changes other than hypertrophy in pathological contexts, including elongation, process extension toward injury site, and some three-dimensional (3D) domain overlap26.”

What the sources say

• Supported

  The review’s “Dealing With Insults” section describes polarized, elongated reactive astrocytes extending long processes toward injury sites. It also reports that, after more severe injury, processes extend into adjacent astrocyte domains, supporting the claim of some domain overlap. The indexed passages do not provide page numbers. (LLM, conf=0.91)

  cites [26] Schiweck, J., Eickholt, B. J. & Murk, K. Important shapeshifter: mechanisms allowing astrocytes to respond to the changing nervous system during development, injury and disease. Front. Cell. Neurosci. 12, 261 (2018). source

In the paper

“Increased GFAP immunoreactivity largely reflects changes in the astrocytic cytoskeleton and tends to exaggerate the degree of hypertrophy because, with the exception of scar-border astrocytes, the volume accessed by reactive astrocytes does not change, as they remain in their territorial domains23.”

What the sources say

• Partly supported

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

  cites [23] Wilhelmsson, U. et al. Redefining the concept of reactive astrocytes as cells that remain within their unique domains upon reaction to injury. Proc. Natl Acad. Sci. USA 103, 17513–17518 (2006). The complete visualization of astrocytes using whole-cell filling techniques revealed that reactive astrocytes display subtle morphological changes and remain in their 3D territorial domain, highlighting that GFAP immunostaining overestimates the true degree of astrocyte hypertrophy. sourceExperimental — accuracy not yet measured

In the paper

“In addition, the expression of some of these proteins may change in reactive astrocytes22 (Table 1), and some might be expressed by other cell types in specific brain regions13.”

What the sources say

• Supported

  Citation 22 is attached to the first clause, about protein expression changing in reactive astrocytes; the claim about expression by other cell types is attached to citation 13. In “Phenotypic Change But Constant Number of Astrocytes in AD,” the paper distinguishes resting GFAP-negative astrocytes from reactive GFAP-positive astrocytes, supporting the cited clause. (LLM, conf=0.92)

  cites [22] Serrano-Pozo, A., Gómez-Isla, T., Growdon, J. H., Frosch, M. P. & Hyman, B. T. A phenotypic change but not proliferation underlies glial responses in Alzheimer disease. Am. J. Pathol. 182, 2332–2344 (2013). source
• Supported

  Citation 13 is attached to the second clause, about proteins expressed by other cell types in specific brain regions; the reactive-astrocyte clause has a different citation. The Discussion (page not provided) reports that glutamine synthetase, used as an astrocyte marker, is also expressed by thalamic oligodendrocytes. (LLM, conf=0.93)

  cites [13] Griemsmann, S. et al. Characterization of panglial gap junction networks in the thalamus, neocortex, and hippocampus reveals a unique population of glial cells. Cereb. Cortex 25, 3420–3433 (2015). source

In the paper

“Such transcriptomic profiling specifically shows that reactive astrocytes adopt distinct molecular states in different disease models48,66–70, in different CNS regions70, and in brain tumors71.”

What the sources say

• Partly supported

  The Extended Data compare RNA-seq profiles of spinal-cord-injury reactive astrocytes with previously reported forebrain stroke-reactive astrocytes; only 58.5% of the top elevated forebrain genes were also significantly elevated after spinal cord injury. This supports molecular differences between those contexts, but disease model and CNS region change together, so the paper does not establish distinct states attributable to region independently. The brain-tumor clause is attached to a different citation. (LLM, conf=0.83)

  cites [48] Anderson, M. A. et al. Astrocyte scar formation aids central nervous system axon regeneration. Nature 532, 195–200 (2016). sourceExperimental — accuracy not yet measured
• Supported

  This source is cited for the different-disease-models portion of the sentence, not the CNS-regions or brain-tumors portions. The Introduction describes transcriptomic profiling after ischemic stroke and LPS-induced neuroinflammation and reports gene-expression differences between the two reactive-astrocyte populations. (LLM, conf=0.92)

  cites [66] Zamanian, J. L. et al. Genomic analysis of reactive astrogliosis. J. Neurosci. 32, 6391–6410 (2012). First evidence for molecular heterogeneity of reactive astrocytes using microarray-based transcriptomics of acutely isolated astrocytes from mouse models of ischemia and septic shock. Studies in virtually all models of CNS diseases followed. source
• ?Not checked — no full text of the sourcecites [67] Orre, M. et al. Isolation of glia from Alzheimer’s mice reveals inflammation and dysfunction. Neurobiol. Aging 35, 2746–2760 (2014). source
• Partly supported

  The Results section, “Injury-Induced Changes of Gene Expression in the Cerebral Cortex GM Astrocytes” (page unavailable), reports transcriptomic differences between reactive and nonreactive astrocytes after cortical injury. The Introduction describes a stab-wound model and comparison with neural stem cells, not reactive astrocytes across different disease models or CNS regions. The brain-tumor clause is attached to citation 71, not this source. (LLM, conf=0.83)

  cites [68] Sirko, S. et al. Astrocyte reactivity after brain injury-: The role of galectins 1 and 3. Glia 63, 2340–2361 (2015). sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites [69] Diaz-Castro, B., Gangwani, M. R., Yu, X., Coppola, G. & Khakh, B. S. Astrocyte molecular signatures in Huntington’s disease. Sci. Transl. Med. 11, eaaw8546 (2019). source
• Partly supported

  The Results section, “Regional Differences in Astrocyte-Specific Gene Expression During EAE” (page unavailable), reports distinct astrocyte gene-expression patterns across CNS regions during EAE. This paper studies one disease model, so it does not itself establish differences between disease models. The brain-tumor clause is attached to citation 71, not this source. (LLM, conf=0.86)

  cites [70] Itoh, N. et al. Cell-specific and region-specific transcriptomics in the multiple sclerosis model: Focus on astrocytes. Proc. Natl Acad. Sci. USA 115, E302–E309 (2018). sourceExperimental — accuracy not yet measured
• Partly supported

  The Results section on malignant glioma reports distinct expression-profile correlations between astrocyte subpopulations and glioblastoma subtypes, and the Discussion describes molecularly distinct populations emerging during tumor progression. This supports the brain-tumor portion attached to this citation, but the paper does not establish that reactive astrocytes adopt those states; it studies astrocyte subpopulations and their malignant glioma analogs. (LLM, conf=0.86)

  cites [71] John Lin, C. C. et al. Identification of diverse astrocyte populations and their malignant analogs. Nat. Neurosci. 20, 396–405 (2017). sourceExperimental — accuracy not yet measured

In the paper

“For example, the manipulation of reactive astrocytes has resulted in improved outcomes38,42,43, worse35 outcomes, and no change44 in mouse models of AD and MS40,45,46.”

What the sources say

• Supported

  The citation supports the improved-outcomes part of the sentence. In Results, “Astrocytic CN/NFAT inhibition improves cognition” reports that astrocyte-targeted Gfa2-VIVIT treatment improved cognitive performance in APP/PS1 mice, a mouse model of AD. The worse-outcomes and no-change parts have separate citations and are not attributed to this paper. (LLM, conf=0.92)

  cites [38] Furman, J. L. et al. Targeting astrocytes ameliorates neurologic changes in a mouse model of Alzheimer’s disease. J. Neurosci. 32, 16129–16140 (2012). source
• Supported

  The citation is attached to the improved-outcomes portion of the sentence, not the worse, no-change, or MS examples. The Discussion reports that inhibiting astrocyte reactivity through the JAK2-STAT3 pathway reduced amyloid deposition, improved spatial learning, and restored synaptic function in mouse models of AD. (LLM, conf=0.94)

  cites [42] Ceyzériat, K. et al. Modulation of astrocyte reactivity improves functional deficits in mouse models of Alzheimer’s disease. Acta Neuropathol. Commun. 6, 104 (2018). source
• Supported

  The Discussion reports that genetic modulation of astrogliosis improved pathology and cognition in a mouse model of AD. In the citing sentence, this paper supports the improved-outcomes example; the worse-outcomes, no-change, and MS examples have separate citations. (LLM, conf=0.93)

  cites [43] Reichenbach, N. et al. Inhibition of Stat3-mediated astrogliosis ameliorates pathology in an Alzheimer’s disease model. EMBO Mol. Med. 11, e9665 (2019). source
• Supported

  The citation to this paper is attached to “worse outcomes,” not to the improved, unchanged, or MS outcomes. The Abstract reports that deleting Gfap and Vim to attenuate astrocyte activation in APP/PS1 mice doubled amyloid plaque load and increased dystrophic neurites; the Discussion likewise reports increased plaque load. (LLM, conf=0.93)

  cites [35] Kraft, A. W. et al. Attenuating astrocyte activation accelerates plaque pathogenesis in APP/PS1 mice. FASEB J. 27, 187–198 (2013). source
• ?Not checked — no full text of the sourcecites [44] Kamphuis, W. et al. GFAP and vimentin deficiency alters gene expression in astrocytes and microglia in wild-type mice and changes the transcriptional response of reactive glia in mouse model for Alzheimer’s disease. Glia 63, 1036–1056 (2015). source

In the paper

“In this study, ‘homeostatic astrocytes’ were predominant in healthy mice, whereas ‘disease-associated astrocytes’ were unique to AD mice.”

What the sources say

• Partly supported

  The paper reports a homeostatic Gfap-low state in wild-type mice and a disease-associated astrocyte state observed only in AD mice in its initial comparison (Abstract; no page given). But its age-series analysis also finds DAA-like cells in older wild-type mice, so the unqualified claim that they were unique to AD mice overstates the finding. (LLM, conf=0.87)

  cites [78] Habib, N. et al. Disease-associated astrocytes in Alzheimer’s disease and aging. Nat. Neurosci. 23, 701–706 (2020). sourceExperimental — accuracy not yet measured

In the paper

“Functions lost or altered in reactive astrocytes include neurotransmitter and ion buffering in mouse HD models58, communication via gap junctions in the sclerotic hippocampus of patients with epilepsy59, phagocytic clearance of dystrophic neurites60, and metabolic coupling by glycolysis-derived d-serine61 and lactate62 in mouse AD models.”

What the sources say

• Partly supported

  The Discussion reports reduced GLT-1 and Kir4.1 expression and impaired extracellular potassium maintenance in HD mouse models, supporting altered neurotransmitter and ion buffering. But it says these early functional changes occurred without astrogliosis; the Results likewise found little or no striatal astrogliosis at symptomatic ages. This source therefore does not support describing the affected astrocytes as reactive. (LLM, conf=0.90)

  cites [58] Tong, X. et al. Astrocyte Kir4.1 ion channel deficits contribute to neuronal dysfunction in Huntington’s disease model mice. Nat. Neurosci. 17, 694–703 (2014). Demonstration with targeted molecular manipulations that loss of astrocyte homeostatic functions contributes to HD pathogenesis. sourceExperimental — accuracy not yet measured
• Supported

  The Discussion reports a complete lack of glial gap-junction coupling in the sclerotic hippocampus of patients with mesial temporal lobe epilepsy. This supports the portion of the citing sentence attached to citation 59; the other functions are attributed to other citations. No page number was available in our copy. (LLM, conf=0.94)

  cites [59] Bedner, P. et al. Astrocyte uncoupling as a cause of human temporal lobe epilepsy. Brain 138, 1208–1222 (2015). source
• Supported

  The Discussion reports that reactive astrocytes enwrap, internalize and degrade presynaptic dystrophies in APP/PS1 mice, with evidence of phagocytosis of dystrophies in human AD samples. It also notes that this phagocytic capacity might become impaired during disease progression. Citation 60 supports the phagocytic-clearance portion of the sentence; the other functions have separate citations. (LLM, conf=0.93)

  cites [60] Gomez-Arboledas, A. et al. Phagocytic clearance of presynaptic dystrophies by reactive astrocytes in Alzheimer’s disease. Glia 66, 637–653 (2018). source

In the paper

“hiPSC-derived astrocytes are also amenable to study responses to viral infection83 and to specific stimuli84.”

What the sources say

• Supported

  The Results section (‘Human iPSC-derived astrocytes are preferentially infected...’; page not provided) describes infecting hiPSC-derived astrocytes with Zika virus and measuring their infection rate and cellular changes. This supports the viral-infection part attached to citation 83; the separate claim about specific stimuli is attached to citation 84. (LLM, conf=0.93)

  cites [83] Ledur, P. F. et al. Zika virus infection leads to mitochondrial failure, oxidative stress and DNA damage in human iPSC-derived astrocytes. Sci. Rep. 10, 1218 (2020). source
• Supported

  Citation 84 is attached to the claim about responses to specific stimuli; the viral-infection claim is attributed to citation 83, not this paper. The Introduction says the authors assessed astrocyte profiles triggered by different neuroinflammatory stimuli, and the Discussion reports distinct responses to those stimuli. (LLM, conf=0.93)

  cites [84] Perriot, S. et al. Human induced pluripotent stem cell-derived astrocytes are differentially activated by multiple sclerosis-associated cytokines. Stem Cell Reports 11, 1199–1210 (2018). source

In the paper

“Studies in rodents document region-dependent and often contradictory changes in aging astrocytes, such as an increase in cellular volume and overlap of astrocyte processes, but also atrophy, increase in GFAP content, or even a reduction in the number of GFAP+ and GS+ astrocytes87–89.”

What the sources say

• ?Not checked — no full text of the sourcecites [87] Rodríguez, J. J. et al. Complex and region-specific changes in astroglial markers in the aging brain. Neurobiol. Aging 35, 15–23 (2014). source
• Partly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites [88] Cerbai, F. et al. The neuron-astrocyte-microglia triad in normal brain ageing and in a model of neuroinflammation in the rat hippocampus. PLoS One 7, e45250 (2012). sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites [89] O’Callaghan, J. P. & Miller, D. B. The concentration of glial fibrillary acidic protein increases with age in the mouse and rat brain. Neurobiol. Aging 12, 171–174 (1991). source

In the paper

“Interestingly, astrocytes generated from hiPSC derived from fibroblasts obtained from patients with CNS diseases (usually with a genetic mutation causative of disease or a risk polymorphism) show pathological phenotypes, including dysregulation of lipid metabolism11, alteration in the contents of the extracellular vesicles released by astrocytes80, reduced autophagy81, or altered STAT3 signaling82”

What the sources say

• Supported

  Citation 11 is attached to the lipid-metabolism example, not the separately cited extracellular-vesicle, autophagy, or STAT3 examples. The Results section (‘APOE4 astrocytes exhibit compromised Aβ uptake’; page not available) reports altered lipid-metabolism gene expression and cholesterol levels in APOE4 iPSC-derived astrocytes. (LLM, conf=0.93)

  cites [11] Lin, Y. T. et al. APOE4 causes widespread molecular and cellular alterations associated with Alzheimer’s disease phenotypes in human iPSC-derived brain cell types. Neuron 98, 1141–1154.e7 (2018). Technically improved generation of hiPSC-derived astrocytes demonstrates that astrocytes harboring a genetic risk factor for AD are diseased astrocytes that may further exacerbate ongoing pathology. source
• Partly supported

  The Results section (“MicroRNAs regulating axonal maintenance are selectively dysregulated in C9 patient ADEVs”; page unavailable) reports altered miRNA cargo in extracellular vesicles released by C9orf72-ALS patient astrocytes, supporting the point attached to this citation. However, the Materials and methods section (“Conversion of skin fibroblasts to induced neural progenitor cells”; page unavailable) describes direct conversion of patient fibroblasts to neural progenitor cells and then astrocytes, not generation through hiPSCs. (LLM, conf=0.88)

  cites [80] Varcianna, A. et al. Micro-RNAs secreted through astrocyte-derived extracellular vesicles cause neuronal network degeneration in C9orf72 ALS. EBioMedicine 40, 626–635 (2019). sourceExperimental — accuracy not yet measured
• Supported

  Citation 81 is attached to the reduced-autophagy example, not to the other phenotypes listed with separate citations. The Results sections on generating patient-specific astrocytes and impaired macroautophagy report that astrocytes derived from iPSCs of patients with LRRK2-associated Parkinson’s disease had reduced autophagic function compared with controls (page not specified). (LLM, conf=0.92)

  cites [81] di Domenico, A. et al. Patient-specific iPSC-derived astrocytes contribute to non-cell-autonomous neurodegeneration in Parkinson’s disease. Stem Cell Reports 12, 213–229 (2019). source

In the paper

“Astrocyte Ca2+ dynamics and network responses become aberrant in mouse models of HD53, AD54, and ALS55, possibly contributing to cognitive impairment and neuropathology43,53,56.”

What the sources say

• Partly supported

  The Significance Statement (p. 2) and Discussion (p. 16) support aberrant astrocyte Ca2+ signaling and altered circuit engagement in HD model mice. The paper suggests these changes may contribute to altered striatal function, but it does not establish a contribution to cognitive impairment; the Discussion (p. 17) says a mechanism linking the cellular findings to HD symptoms remains unresolved. The AD and ALS portions of the citing sentence have separate citations and are not attributed to this source. (LLM, conf=0.84)

  cites [53] Jiang, R., Diaz-Castro, B., Looger, L. L. & Khakh, B. S. Dysfunctional calcium and glutamate signaling in striatal astrocytes from Huntington’s disease model mice. J. Neurosci. 36, 3453–3470 (2016). sourceExperimental — accuracy not yet measured
• Supported

  Citation 54 is attached to the AD portion of the sentence, not the HD or ALS portions. The paper’s Abstract reports elevated resting astrocyte calcium, more frequent and synchronized calcium transients, and intercellular calcium waves in an AD mouse model. It also suggests a possible contribution to memory disorders, without establishing one. (LLM, conf=0.93)

  cites [54] Kuchibhotla, K. V., Lattarulo, C. R., Hyman, B. T. & Bacskai, B. J. Synchronous hyperactivity and intercellular calcium waves in astrocytes in Alzheimer mice. Science 323, 1211–1215 (2009). source
• Supported

  The citation to this paper is attached to ALS, not the separately cited HD and AD models or the later claim about cognitive impairment. In the Results section (“Superoxide production enhances microdomain Ca2+ transients”; page unavailable), astrocytes in symptomatic SOD1G93A ALS mice had greater Ca2+ microdomain activity than age-matched controls, supporting the attributed change in astrocyte Ca2+ dynamics. (LLM, conf=0.91)

  cites [55] Agarwal, A. et al. Transient opening of the mitochondrial permeability transition pore induces microdomain calcium transients in astrocyte processes. Neuron 93, 587–605.e7 (2017). Technically refined application of Ca2+ imaging approaches and machine learning unraveled dysregulation of Ca2+ responses in a mouse model of ALS. source

In the paper

“These studies also suggested complex functional changes in reactive astrocytes, including novel regenerative functions70, proliferation, and neural stem cell potential68, as well as loss of homeostatic functions66.”

What the sources say

• Supported

  Citation 66 is attached to the loss of homeostatic functions, not the separately cited regenerative, proliferative, or stem-cell claims. The Results section on cholesterol synthesis reports decreased expression of that pathway in EAE astrocytes compared with normal astrocytes, supporting the cited point as a suggested change in homeostatic function. (LLM, conf=0.88)

  cites [70] Itoh, N. et al. Cell-specific and region-specific transcriptomics in the multiple sclerosis model: Focus on astrocytes. Proc. Natl Acad. Sci. USA 115, E302–E309 (2018). source
• Supported

  Citation 68 is attached to proliferation and neural stem cell potential, not to the separately cited regenerative or homeostatic claims. The Introduction describes a subset of proliferating reactive astrocytes acquiring neural stem cell potential after injury, and the Discussion reports proliferation-related gene expression while noting that only about 10–20% divide in this injury model. (LLM, conf=0.91)

  cites [68] Sirko, S. et al. Astrocyte reactivity after brain injury-: The role of galectins 1 and 3. Glia 63, 2340–2361 (2015). source
• ?Could not verify

  Citation 66 is attached to the claim that reactive astrocytes lose homeostatic functions. The Discussion describes extensive gene-expression changes and identifies transporters and channels involved in homeostasis, but does not say that homeostatic functions are lost. Searches for loss of homeostatic function and down-regulation of homeostatic genes found no passage establishing that point. (LLM, conf=0.73)

  cites [66] Zamanian, J. L. et al. Genomic analysis of reactive astrogliosis. J. Neurosci. 32, 6391–6410 (2012). First evidence for molecular heterogeneity of reactive astrocytes using microarray-based transcriptomics of acutely isolated astrocytes from mouse models of ischemia and septic shock. Studies in virtually all models of CNS diseases followed. sourceExperimental — accuracy not yet measured

In the paper

“For example, activation of STAT3-dependent transcription is beneficial in neonatal white matter injury47, traumatic brain injury30, spinal cord injury48,49, and motor neuron injury50, but detrimental in AD models42,43.”

What the sources say

• Supported

  Citation 47 supports the neonatal white matter injury portion of the sentence, not the separately cited injury and AD claims. The Abstract Results report that deleting astrocytic STAT3 exacerbated injury in a neonatal mouse model, and the Discussion describes a protective role for STAT3-mediated reactive astrocytes and a potential benefit of promoting pathway activation. (LLM, conf=0.88)

  cites [47] Nobuta, H. et al. STAT3-mediated astrogliosis protects myelin development in neonatal brain injury. Ann. Neurol. 72, 750–765 (2012). source
• Partly supported

  The Results section ('Acute STAT3 activation is important for cell integrity and apoptosis after astrocyte injury'; page unavailable) reports that STAT3-deficient astrocytes survived mechanical stretching less well than controls. The paper also reports protective effects after spinal cord injury, but the cited evidence does not establish a benefit of STAT3-dependent transcription in traumatic brain injury specifically. (LLM, conf=0.85)

  cites [30] Levine, J. et al. Traumatically injured astrocytes release a proteomic signature modulated by STAT3-dependent cell survival. Glia 64, 668–694 (2016). sourceExperimental — accuracy not yet measured
• Supported

  The citation to this paper is attached to the spinal cord injury portion of the sentence, not the other injuries or AD models. In Results, “Axon regrowth in spite of scar formation” reports that STAT3 conditional knockout significantly attenuated stimulated axon regrowth after spinal cord injury, supporting a beneficial role for STAT3-dependent astrocyte responses in that setting. (LLM, conf=0.90)

  cites [48] Anderson, M. A. et al. Astrocyte scar formation aids central nervous system axon regeneration. Nature 532, 195–200 (2016). source
• Supported

  The citation to this paper is attached to the spinal cord injury part of the sentence, not the other injury types or AD models. The Discussion (page not provided) says that astrocytic STAT3 signaling restricts inflammation and lesion size, preserving functional tissue after spinal cord injury. (LLM, conf=0.92)

  cites [49] Herrmann, J. E. et al. STAT3 is a critical regulator of astrogliosis and scar formation after spinal cord injury. J. Neurosci. 28, 7231–7243 (2008). source

In the paper

“Lastly, responses of reactive astrocytes may be maladaptive and result in malfunctional astrocytes, which, in addition to losing homeostatic functions, may also gain detrimental functions, thus exacerbating ongoing pathology6.”

What the sources say

• ?Could not verify

  The indexed passages are a HAL repository listing and site navigation, with no section or page of the paper’s substantive text. Searches for maladaptive responses, loss of homeostatic functions, detrimental functions, and worsening pathology returned no passage addressing the claim. (LLM, conf=0.72)

  cites [6] Escartin, C., Guillemaud, O. & Carrillo-de Sauvage, M. A. Questions and (some) answers on reactive astrocytes. Glia 67, 2221–2247 (2019). sourceExperimental — accuracy not yet measured

In the paper

“are rapidly becoming commonplace in basic research11,82 and therapy development109”

What the sources say

• Supported

  The citation to this paper is attached to “basic research,” while a separate citation accompanies “therapy development.” In Results (“Generation of isogenic APOE iPSC-derived neurons, astrocytes, and microglia-like cells”; page unavailable), the authors describe deriving iPSC-derived astrocytes for their Alzheimer’s disease experiments. The paper therefore serves as an example of their use in basic research. (LLM, conf=0.86)

  cites [11] Lin, Y. T. et al. APOE4 causes widespread molecular and cellular alterations associated with Alzheimer’s disease phenotypes in human iPSC-derived brain cell types. Neuron 98, 1141–1154.e7 (2018). Technically improved generation of hiPSC-derived astrocytes demonstrates that astrocytes harboring a genetic risk factor for AD are diseased astrocytes that may further exacerbate ongoing pathology. source
• Partly supported

  The Methods describe experiments with hiPSC-derived astrocytes, and the Discussion says human iPSC models can help identify astrocytic targets for potential treatment. This supports their relevance to therapy development, but the paper does not establish that their use is rapidly becoming commonplace. (LLM, conf=0.84)

  cites [82] Tyzack, G. E. et al. A neuroprotective astrocyte state is induced by neuronal signal EphB1 but fails in ALS models. Nat. Commun. 8, 1164 (2017). sourceExperimental — accuracy not yet measured
• Partly supported

  The Results section (“Generation and Characterization of Human iAstrocytes”; page unavailable) shows that the authors generated hiPSC-derived astrocytes as a research model, and the Methods show their use in testing siponimod. This provides an example relevant to basic research and therapy investigation, but the paper does not establish that such use is rapidly becoming commonplace. (LLM, conf=0.82)

  cites [109] Colombo, E. et al. Siponimod (BAF312) activates Nrf2 while hampering NFκB in human astrocytes, and protects from astrocyte-induced neurodegeneration. Front. Immunol. 11, 635 (2020). sourceExperimental — accuracy not yet measured

In the paper

“hiPSC-derived astrocytes, which can be generated with a fast protocol in 2D layers104 or integrated in 3D systems such as spheroids and organoids105–108”

What the sources say

• Supported

  The cited paper supports the portion marked 104: it reports rapid generation of astrocytes from human PSCs, including patient-derived iPSCs, and its Methods describe culturing them on coated dishes (2D). The spheroid and organoid portion is assigned to citations 105–108, not to this source. The supplied copy gives section labels but no page numbers. (LLM, conf=0.91)

  cites [104] Tchieu, J. et al. NFIA is a gliogenic switch enabling rapid derivation of functional human astrocytes from pluripotent stem cells. Nat. Biotechnol. 37, 267–275 (2019). source
• Supported

  The Results section, “Generation and purification of astrocyte-lineage cells from iPSC-derived hCS,” describes generating human astrocytes in 3D cerebral cortical spheroids. The fast 2D protocol is attached to citation 104, not to this source; Sloan et al. supports the spheroid example in the 3D portion of the sentence. (LLM, conf=0.92)

  cites [105] Sloan, S. A. et al. Human astrocyte maturation captured in 3D cerebral cortical spheroids derived from pluripotent stem cells. Neuron 95, 779–790.e6 (2017). source
• Partly supported

  The Results section (‘Generation of cerebral organoids’; page unavailable) reports 3D cerebral organoids generated from human induced pluripotent stem cells. It does not report hiPSC-derived astrocytes being integrated into those organoids or into spheroids. The fast 2D protocol is attached to a different citation and is not assessed here. (LLM, conf=0.85)

  cites [106] Lancaster, M. A. et al. Cerebral organoids model human brain development and microcephaly. Nature 501, 373–379 (2013). sourceExperimental — accuracy not yet measured
• Supported

  The citation to this paper falls in the 3D-systems portion of the sentence, not the fast 2D-protocol portion. The Methods identify an hiPSC line used to generate cerebral organoids, and “Protracted in vitro development of human whole-brain organoids” reports that GFAP+ astroglia emerged in those organoids. No page numbers are available in our copy. (LLM, conf=0.88)

  cites [107] Quadrato, G. et al. Cell diversity and network dynamics in photosensitive human brain organoids. Nature 545, 48–53 (2017). source
• Partly supported

  The Results section (‘Air-liquid interface culture of cerebral organoids leads to improved survival and maturation’; page unavailable) reports astrocytes in cerebral organoids, supporting the 3D-organoid part of the cited claim. The Methods section (‘Human pluripotent stem cell culture and genome editing’; page unavailable) specifies that the organoids were generated from human embryonic stem cells, not hiPSCs. The fast 2D protocol is attached to a different citation and is not assessed here. (LLM, conf=0.88)

  cites [108] Giandomenico, S. L. et al. Cerebral organoids at the air-liquid interface generate diverse nerve tracts with functional output. Nat. Neurosci. 22, 669–679 (2019). sourceExperimental — accuracy not yet measured

In the paper

“Emerging reactive-astrocyte biomarkers are either measured in blood or cerebrospinal fluid (for example, YKL-40)115 or used for brain imaging, such as MAO-B-based positron emission tomography (PET)116”

What the sources say

• Supported

  The Methods report measuring YKL-40 in CSF and paired plasma samples. The Discussion identifies YKL-40 as an astrocyte-derived CSF biomarker and also describes plasma measurements. The separate citation for MAO-B PET is not being judged here. (LLM, conf=0.93)

  cites [115] Craig-Schapiro, R. et al. YKL-40: a novel prognostic fluid biomarker for preclinical Alzheimer’s disease. Biol. Psychiatry 68, 903–912 (2010). source
• ?Not checked — no full text of the sourcecites [116] Carter, S. F. et al. Evidence for astrocytosis in prodromal Alzheimer disease provided by 11C-deuterium-L-deprenyl: a multitracer PET paradigm combining 11C-Pittsburgh compound B and 18F-FDG. J. Nucl. Med. 53, 37–46 (2012). Non-invasive imaging of reactive astrocytes in human patients. source

In the paper

“Optogenetics25 and designer receptors exclusively activated by designer drugs (DREADDs)25 are potential tools to manipulate reactive astrocytes or to restore their aberrant Ca2+ signaling observed in mouse models of neurodegenerative diseases53–55.”

What the sources say

• ?Not checked — no full text of the sourcecites [25] Yu, X., Nagai, J. & Khakh, B. S. Improved tools to study astrocytes. Nat. Rev. Neurosci. 21, 121–138 (2020). source
• Supported

  The citation to this paper is attached to aberrant Ca2+ signaling in disease-model mice, not to the proposed use of optogenetics or DREADDs. The Discussion (p. 16) reports altered spontaneous and evoked astrocyte Ca2+ signals in the R6/2 Huntington’s disease mouse model. This paper supports that example, although it does not test those proposed tools. (LLM, conf=0.91)

  cites [53] Jiang, R., Diaz-Castro, B., Looger, L. L. & Khakh, B. S. Dysfunctional calcium and glutamate signaling in striatal astrocytes from Huntington’s disease model mice. J. Neurosci. 36, 3453–3470 (2016). source
• Supported

  The paper reports aberrant astrocytic Ca2+ signaling in an Alzheimer’s disease mouse model: elevated resting calcium, more frequent transients, and intercellular calcium waves (Abstract). The proposed use of optogenetics and DREADDs is not attributed to this source; separate citations accompany those tools in the citing sentence. (LLM, conf=0.92)

  cites [54] Kuchibhotla, K. V., Lattarulo, C. R., Hyman, B. T. & Bacskai, B. J. Synchronous hyperactivity and intercellular calcium waves in astrocytes in Alzheimer mice. Science 323, 1211–1215 (2009). source
• Supported

  The citation to this paper supports the sentence’s claim about aberrant Ca2+ signaling in a mouse model of neurodegenerative disease. In Results, “Superoxide production enhances microdomain Ca2+ transients” (page unavailable), the authors report increased astrocyte microdomain activity in symptomatic SOD1G93A mice, an ALS model. The separate citation to optogenetics and DREADDs is not attributed to this source. (LLM, conf=0.91)

  cites [55] Agarwal, A. et al. Transient opening of the mitochondrial permeability transition pore induces microdomain calcium transients in astrocyte processes. Neuron 93, 587–605.e7 (2017). Technically refined application of Ca2+ imaging approaches and machine learning unraveled dysregulation of Ca2+ responses in a mouse model of ALS. source

In the paper

“Alternatively, the diversity within astrocyte populations from mouse models may be dissected out by combining fluorescence-activated cell sorting (FACS) and cell-surface markers identified in screens71.”

What the sources say

• Supported

  The Results section (‘Prospective identification of diverse astrocyte populations’) describes combining an Aldh1l1–GFP reporter mouse with screened cell-surface markers in a FACS-based approach. The authors report that antibodies identified by the screen subdivided the mouse astrocyte population, matching the citing sentence. (LLM, conf=0.94)

  cites [71] John Lin, C. C. et al. Identification of diverse astrocyte populations and their malignant analogs. Nat. Neurosci. 20, 396–405 (2017). source

In the paper

“Immunohistochemical staining for cytosolic enzymes such as ALDH1L1, ALDOC, GS, and S100B allow the visualization of the somata and proximal processes of astrocytes, although, like GFAP, these markers fail to reveal small processes.”

In the paper

“In the healthy mouse brain, hippocampal astrocytes have a higher GFAP content than cortical, thalamic, or striatal astrocytes; this, however, does not make hippocampal astrocytes more reactive.”

In the paper

“Finally, there are discrepancies between observed GFAP mRNA and protein levels, perhaps due to differential regulation of translation, post-translational modifications, protein half-life, and antibody epitope accessibility.”

In the paper

“By definition, astrocyte reactivity is secondary to an extrinsic signal, may evolve with time, and, in many situations, is reversible.”

In the paper

“Numerous mixed scenarios of malfunctional and resilient astrocytes plausibly exist, with multidirectional transitions among them.”

In the paper

“In summary, GFAP upregulation and hypertrophy are useful but insufficient markers of astrocyte reactivity that need to be complemented by additional markers (Table 1 and Box 1).”

In the paper

“Notably, isolation protocols may not always be optimal for astrocytes, resulting in low numbers of cells or nuclei being sequenced, and some highly relevant but weakly expressed transcripts, such as transcription factors and plasma-membrane receptors, may be overlooked, particularly in snRNAseq.”

In the paper

“In addition, generation of astrocytes from neural stem cells is inherently difficult, and derivation and culture conditions have not yet been standardized, leading to diversity of clone phenotypes.”

In the paper

“In addition, vague and binary terms such as ‘neuroprotective’ or ‘neurotoxic’ are best avoided in describing astrocyte phenotypes as they are too simplistic to be meaningful, unless they are suppor ted by specific molecular mechanisms and direct causative experi mental evidence.”

In the paper

“In addition, although astrocytes appear to be more resistant than neurons to degeneration and death, loss of primary and secondary astrocyte branches has been reported in mouse models of AD27 and ALS18, and in patients with multiple sclerosis (MS)28.”

What the sources say

• ?Not checked — no full text of the sourcecites [27] Olabarria, M., Noristani, H. N., Verkhratsky, A. & Rodríguez, J. J. Concomitant astroglial atrophy and astrogliosis in a triple transgenic animal model of Alzheimer’s disease. Glia 58, 831–838 (2010). source
• ?Not checked — no full text of the sourcecites [18] Rossi, D. et al. Focal degeneration of astrocytes in amyotrophic lateral sclerosis. Cell Death Differ. 15, 1691–1700 (2008). source
• ?Not checked — no full text of the sourcecites [28] Black, J. A., Newcombe, J. & Waxman, S. G. Astrocytes within multiple sclerosis lesions upregulate sodium channel Nav1.5. Brain 133, 835–846 (2010). source

In the paper

“That is, STAT3-mediated transcriptional programs may contribute to malfunctional astrocyte states in AD models and to resilient states in other conditions.”

In the paper

“In addition, the term ‘homeostatic astrocytes’ implies the unproven assumption that other transcriptional astrocyte clusters are dys-homeostatic, while they may be successful homeostasis-preserving adaptations to disease.”

In the paper

“Healthy brain aging is not pathological and may be defined as an adaptive evolution of global cell physiology over time85.”

What the sources say

• ?Not checked — no full text of the sourcecites [85] Rodríguez-Arellano, J. J., Parpura, V., Zorec, R. & Verkhratsky, A. Astrocytes in physiological aging and Alzheimer’s disease. Neuroscience 323, 170–182 (2016). source

In the paper

“Arguably, new names are needed to capture the variety of reactive astrocytes, but current knowledge does not yet allow the objective categorizing of reactive astrocytes.”

In the paper

“An important conclusion drawn from these studies is that the morphological appearance of astrocytes does not correlate with functional phenotypes or with their impact on other cell types.”

In the paper

“We stress that the expression in full or in part of a predetermined correlative signature of molecular markers is not, on its own, sufficient to define a functional phenotype of reactive astrocyte.”

In the paper

“Importantly, molecular signatures based on the expression of genes or proteins need to be validated by assessing specific astrocyte functions (Table 2), since post-transcriptional and post-translational events critically shape functional outcomes.”

In the paper

“Acute metabolic damage with the mitochondrial toxin MPTP does not replicate chronic Parkinson’s disease (PD), to cite another example of in vivo inappropriate modelling.”