bims-microg 2025-07-20 papers

bims-microg

Biomed News

on Microglia in health and disease

Issue of 2025–07–20
27 papers selected by
Marcus Karlstetter, Universität zu Köln

Response of spatially defined microglia states with distinct chromatin accessibility in a mouse model of Alzheimer's disease.
Acrylamide-induced noradrenergic axon degeneration is promoted via a non-cell autonomous mechanism, involving microglial Tnfaip2/TNF-α and oxidative stress pathways.
Amyloid-β plaque-associated microglia drive TSPO upregulation in Alzheimer's disease.
Targeting complement C3/C3aR pathway restores rejuvenation factor PF4 and mitigates neurocognitive impairments in age-related perioperative neurocognitive disorders.
From Cells to Circuits: New Mechanistic Insights From Striatal Interneurons and Microglia Into the Neurobiology of Tourette Syndrome.
Rod-shaped microglia represent a morphologically distinct subpopulation of disease-associated microglia.
Inhibition of microglia priming by NLRP3 reduces the impact of early life stress and mild TBI.
Physiological and injury-induced microglial dynamics across the lifespan.
The knockout of Moesin leads to excess microglia-mediated synaptic pruning and impairs social novelty in a mouse model.
Pu.1/Spi1 dosage controls the turnover and maintenance of microglia in zebrafish and mammals.
Jing An decoction alleviates neuroinflammation in Tourette syndrome by regulating butyrate-mediated microbiota-gut-brain axis.
Activation of Hippocampal ACE2 Prevents the Dysbiosis-induced Depression-like Behavior in Mice by Enhanced Neurogenesis and Neuroprotection via Mas Receptor.
Adrenergic Control of P2Y6 Receptor-Dependent Phagocytosis in Rodent and Human Microglia.
Human iPSC-derived cerebral organoids reveal oxytocin-mediated protection against amyloid-β pathology.
Sialylation as a checkpoint for inflammatory and complement-related retinal diseases.
Interleukin-4 prevents increased endothelial permeability by inducing pericyte survival and modulating microglial responses in diabetic retinopathy.
Novel GLP-1/GIP Dual Receptor Agonist Alleviates Neonatal Hypoxic-Ischemic Encephalopathy by Inhibiting TLR2/NF-κB/NLRP3 Mediated-Neuroinflammation : The role of DA5-CH in neonatal hypoxic-ischemic encephalopathy.
Environmental enrichment attenuates social isolation-exacerbated postoperative cognitive dysfunction in aged mice via inhibition of RAGE-HMGB1 proinflammatory signaling.
High-resolution multimodal visible light optical coherence tomography and scanning laser ophthalmoscopy for in vivo neuronal and vascular retinal imaging in mice.
Tau endo-lysosomal processing in human iPSC-derived microglia is impacted by tau aggregation state, but not by microglial activation status.
Inhibition of Acyl-CoA: Cholesterol Acyltransferase 1 Promotes Shedding of Soluble TREM2 and LRP1-Dependent Phagocytosis of Amyloid β Protein in Microglia.
Identification of Chlamydia pneumoniae and NLRP3 inflammasome activation in Alzheimer's disease retina.
APOE genotype confers context dependent neurovascular vulnerability in immune-vascularized human forebrain organoids.
Identification of Chlamydia pneumoniae and NLRP3 inflammasome activation in Alzheimer's disease retina.
Post-stroke butyrate treatment shows sex-dependent microglial responses but does not improve outcomes in a mouse model of endothelin-1 sensory motor stroke.
Protocol to assess engulfment and degradation of synaptosomes by murine microglia in vitro.
Protocol for performing and analyzing a live-cell imaging-based microglia phagocytosis assay using AI on the Olympus ScanR system.

Nat Neurosci. 2025 Jul 14.

Response of spatially defined microglia states with distinct chromatin accessibility in a mouse model of Alzheimer's disease.

Alberto Ardura-Fabregat, Lance Fredrick Pahutan Bosch, Emile Wogram, Omar Mossad, Roman Sankowski, Philipp Aktories, Lina Kieger, James Cook, Dilara Hasavci, Hatice Ulupinar, Daniel Brock, Fang Wang, Nicola Iovino, Samuel Wald, Sebastian Preissl, Bahtiyar Yilmaz, Daniel Schnepf, Andrew J Macpherson, Thomas Blank, Katrin Kierdorf, Marco Prinz.

Microglial spatial heterogeneity remains a crucial yet not fully answered question in the context of potential cell-directed therapies for Alzheimer's disease (AD). There is an unclear understanding of the dynamics of distinct microglia states adjacent to or far from amyloid-beta (Aβ) plaques and their contributions to neurodegenerative diseases. Here we combine multicolor fluorescence cell fate mapping, single-cell transcriptional analysis, epigenetic profiling, immunohistochemistry and computational modeling to comprehensively characterize the relation of plaque-associated microglia (PAM) and non-plaque-associated microglia (non-PAM) in a mouse model of AD. We show that non-PAM are a distinct and highly dynamic microglial state, transitioning to PAM after Aβ plaque deposition in female mice. Non-PAM modulate the cell population expansion in response to amyloid deposition and rapidly respond to environmental cues. Indeed, Csf1 signaling modulates non-PAM-to-PAM transition during disease progression. Our data suggest that microglia states and their dynamics between each other can have distinct contributions to disease, and they may be targeted for the treatment of AD.

DOI: https://doi.org/10.1038/s41593-025-02006-0
J Hazard Mater. 2025 Jul 03. pii: S0304-3894(25)02041-2. [Epub ahead of print]496 139125

Acrylamide-induced noradrenergic axon degeneration is promoted via a non-cell autonomous mechanism, involving microglial Tnfaip2/TNF-α and oxidative stress pathways.

Cai Zong, Harue Sato, Benoit Schneider, Shigeyuki Shichino, Satoshi Ueha, Bin Wu, Kouji Matsushima, Toshitsugu Okayama, Kazuho Ikeo, Makoto Urushitani, Hidenori Ito, Sho Iwama, Alzahraa Fergany, Sahoko Ichihara, Seiichiroh Ohsako, Gaku Ichihara.

  Environmental toxicants such as acrylamide or 1-bromopropane induce cognitive dysfunction in humans. We previously reported specific noradrenergic neuronal degeneration induced by acrylamide or 1-bromopropane in rodents. In this study, we applied in vivo and in vitro models as well as bulk and single-cell transcriptomic analyses to uncover the underlying mechanisms. RNA-seq of brains of acrylamide-exposed mice revealed a transcriptomic profile involving genes related to multiple neurodegenerative diseases and oxidative stress pathways. Single-cell RNA-seq for microglia identified upregulation of immunoregulation-, inflammation-, and oxidative stress- related pathways, and identified the upregulation of Tnfaip2 (a TNF-α effector), in multiple microglial sub-clusters. Further results of our in vitro interaction model showed that compared to direct acrylamide exposure, exposure to conditioned medium (CM) of acrylamide-exposed BV2 microglia significantly decreased 1C11NE axon density, and RNA-seq for 1C11NE identified similar transcriptomic profiles to those of brains of acrylamide-exposed mice. RNA-seq for BV2 microglia showed upregulation of various oxidative stress related genes. Further inhibition experiments demonstrated that TNF-α inhibition or anti-oxidation alleviated acrylamide-induced axonal degeneration in 1C11NE neurons. Finally, in vivo TNF-α knockout alleviated acrylamide-induced neurotoxicity. Our study demonstrated that acrylamide-induced noradrenergic axon degeneration is promoted via a non-cell autonomous mechanism, involving microglial Tnfaip2/TNF-α and oxidative stress pathways.

Keywords:  Acrylamide; Axon; Microglia; Neurodegeneration; Noradrenergic; Oxidative stress; TNF-α

DOI:  https://doi.org/10.1016/j.jhazmat.2025.139125
Acta Neuropathol. 2025 Jul 17. 150(1): 6

Amyloid-β plaque-associated microglia drive TSPO upregulation in Alzheimer's disease.

Daniel A Martinez-Perez, Jennifer L McGlothan, Alexander N Rodichkin, Karam Abilmouna, Zoran Bursac, Francisco Lopera, Carlos Andres Villegas-Lanau, Tomás R Guilarte.

  Translocator protein 18 kDA (TSPO) imaging using positron emission tomography (PET) is widely used to assess neuroinflammation in Alzheimer's disease (AD). However, the significance of the increase in brain TSPO levels in AD pathophysiology is not known. Here, we show that in the 5XFAD transgenic mouse model, brain TSPO levels increase in an age-, brain region-, and sex-dependent fashion. TSPO levels were first increased in the subiculum at 1.5 months of age in male and female 5XFAD mice compared to wildtype mice. The TSPO increase in the subiculum of 1.5-month 5XFAD mice coincided with the appearance of Aβ aggregation and increased serum Aβ1-42/Aβ1-40 ratio which occurred prior to increased serum neurofilament light chain (Nfl) levels and well before cognitive function deficits. We also discovered that the brain TSPO increase was driven by an expansion of activated microglia in contact with Aβ-plaques, that also expressed higher TSPO levels per microglia than microglia not in contact with plaques. While overall, astrocytes were highly activated, the increased TSPO signal in the 5XFAD mouse brain did not increase in astrocytes. We also compared the 5XFAD mouse findings to postmortem human brain tissue from early-onset autosomal-dominant Presenilin 1 (PSEN1)-E280A mutation AD cases. The results in PSEN1-E280A cases confirmed the 5XFAD mouse findings relevant to increased TSPO levels and an increase in TSPO per microglia contacting Aβ-plaques. In summary, TSPO is an early biomarker of neuroinflammation in the AD brain that first increases in the subiculum simultaneously with increased Aβ aggregation and serum Aβ1-42/Aβ1-40 ratio. The increased TSPO response in the 5XFAD mouse brain and in the brain from PSEN1-E280A mutation AD cases reflects Aβ-plaque-associated microglia with a high TSPO content. This microglia subtype is likely to promote the progression of AD pathology, neurodegeneration, and cognitive decline and their high TSPO content may serve as a target for TSPO ligand-based therapy.

Keywords:   PSEN1-E280A mutation; 5XFAD mice; Alzheimer’s disease; Microglia; Neuroinflammation; TSPO

DOI:  https://doi.org/10.1007/s00401-025-02912-4
Mol Psychiatry. 2025 Jul 14.

Targeting complement C3/C3aR pathway restores rejuvenation factor PF4 and mitigates neurocognitive impairments in age-related perioperative neurocognitive disorders.

Jia-Li Wang, Cai-Hong Ye, Zhong-Fa Teng, Kai Zhou, Li-Li Pan, Man-Duo Ouyan, Zhi Zheng, Meng Lu, Shi-Lei Li, Jing Zhang, Pei-Chan Zheng, Jingjing Zhang, Hui Zhang, Mei-Hong Lin, Liang-Cheng Zhang, Shi-Shi Huang, Xiao-Ning Ren, Ning Zheng, Wen-Lin Wei, Zhenhuan Zhao, Shao-Bin Wang, Zhong-Meng Lai.

Perioperative neurocognitive disorders (PND), including postoperative delirium (POD), delayed neurocognitive recovery (dNCR) and postoperative neurocognitive disorder (PNCD), affect up to 10% of surgical patients older than 60 years, and currently there are no effective therapies to prevent PND. The gut microbiota is linked to PND through the gut-brain axis, promoting neuroinflammation via activation and proliferation of microglia and astrocytes in the central nervous system (CNS). In this study, we show that perioperative use of ceftriaxone, a long-acting β-lactam antibiotic, can prevent the development of PND in elderly surgical patients. This effect is associated with reduced serum complement C3 levels and increased levels of platelet factor 4 (PF4). Using an aged mouse model of PND, we found that C3/C3aR axis mediated the interaction of astroglia and microglia during the early stages of neuroinflammation. Genetic ablation or pharmacological blockade of C3/C3aR signaling pathway suppressed neuroinflammation and attenuated cognitive declines in PND. The C3/C3aR axis is essential for surgery-induced platelet count and circulating PF4 declines, and mice supplemented with recombinant PF4 exhibited reduced neuroinflammation and improved cognitive function. Together, our findings revealed the new roles of the C3/C3aR signaling pathway in platelet dysfunction and neuroinflammation in age-related PND, and these results highlight new potential therapeutic strategies for PND.

DOI: https://doi.org/10.1038/s41380-025-03103-z
Biol Psychiatry. 2025 Aug 01. pii: S0006-3223(25)01221-1. [Epub ahead of print]98(3): 192-194

From Cells to Circuits: New Mechanistic Insights From Striatal Interneurons and Microglia Into the Neurobiology of Tourette Syndrome.

Yulia Worbe.

DOI: https://doi.org/10.1016/j.biopsych.2025.05.022
J Neuroinflammation. 2025 Jul 16. 22(1): 184

Rod-shaped microglia represent a morphologically distinct subpopulation of disease-associated microglia.

Yukio Matsuba, Kenichi Nagata, Yosuke Kadota, Naruhiko Sahara, Takaomi C Saido, Shoko Hashimoto.

  Microglia, resident immune cells of the central nervous system, play an essential role in responding to pathological conditions by adopting diverse activation states and morphologies. Recent single-cell RNA sequencing have revealed that microglial subtypes were heterogeneous based on their gene expression profiles. However, the mechanism on how morphological changes in microglia are correlated with their gene expression profiles remains unclear. The current study aimed to identify a distinct population of rod-shaped microglia, characterized by an elongated morphology, in glutamyl cysteine ligase (GCLC)-deficient mice, a model of glutathione deficiency-induced oxidative stress. In the process of brain atrophy accompanied by neuronal cell death, which was observed in GCLC-KO mice, the rod-shaped microglia emerged in early stages of neurodegeneration and subsequently decreased in number over time. C1q-mediated synaptic pruning has been implicated in microglial activation under pathological conditions. Thus, whether C1q contributes to the formation of rod-shaped microglia was investigated. Notably, the genetic deletion of C1q did not affect the number or distribution of rod-shaped microglia in GCLC-KO mice. These findings suggest that their formation occurs via a C1q-independent mechanism. According to morphological and molecular analyses, the gene expression profile of the rod-shaped microglia was similar to that of the disease-associated microglia (DAM). To investigate the mechanisms underlying their formation, single-nucleus RNA sequencing was performed on cortical tissues collected from GCLC-KO mice. DAM-like microglial clusters were consistently identified. Further, pathway enrichment analysis suggested the potential involvement of the urokinase-type plasminogen activator (uPA, encoded by Plau) signaling. Considering the role of uPA in extracellular matrix degradation and cell migration, it may contribute to the morphological changes in rod-shaped microglia. In addition, the phosphorylation of growth-associated protein 43 (GAP43), a modification linked to structural plasticity, increased in rod-shaped microglia. Based on these findings, uPA signaling and phosphorylated GAP43 may be involved in microglial elongation and alignment along neuronal fibers, which potentially facilitate their migration during early neurodegenerative responses. Taken together, the rod-shaped microglia are a previously unrecognized activated population that emerges early in neurodegeneration and may be involved in disease-related processes. Understanding their molecular regulation can provide insights into early microglial responses and potential therapeutic targets.

Keywords:  Disease associated microglia (DAM); GAP43; Oxidative stress; Rod-shaped microglia; uPA signaling

DOI:  https://doi.org/10.1186/s12974-025-03504-5
J Neuroinflammation. 2025 Jul 17. 22(1): 185

Inhibition of microglia priming by NLRP3 reduces the impact of early life stress and mild TBI.

Fabiola Placeres-Uray, Aditi S Gorthy, Maria Dominguez Torres, Coleen M Atkins.

  Although most patients with mild traumatic brain injury (mTBI) experience rapid recovery, some report persistent chronic symptoms such as cognitive dysfunction. One risk factor for prolonged recovery after mTBI is early life stress (ELS). We hypothesized that ELS mediates prolonged cognitive dysfunction after mTBI by exacerbating the NRLP3 inflammasome signaling pathway, and that these effects could be reversed by inhibiting NLRP3.
METHODS: To test this hypothesis, Sprague Dawley rat pups were maternally separated for 3 h daily from P2-P14. Subsequently, the rats underwent a mild-to-moderate fluid percussion brain injury (1.4 atm) or sham surgery during young adulthood and were then treated with either the NLRP3 inhibitor MCC950 or vehicle.
RESULTS: We found that ELS significantly increased microglia and macrophage cell numbers within the hippocampus during mTBI recovery. Quantitative PCR demonstrated that the combination of ELS and mTBI significantly increased levels of HMGB1, TLR4, NLRP3, caspase 1, and IL-1β mRNA levels in the ipsilateral hippocampus at 24 h after injury. This upregulation was persistent and TLR4, NLRP3, caspase 1, and IL-1β levels remained elevated for up to 2 months after injury. Inhibition of the NLRP3 inflammasome with MCC950 reduced this upregulation both 24 h and 2 months after injury. Hippocampal microglia isolated by fluorescence-activated cell sorting demonstrated increased levels of NLRP3 after ELS alone, but not IL-1β. The upregulation in microglial IL-1β required the combination of ELS and mTBI and was ameliorated with MCC950. Additionally, MCC950 treatment improved glucocorticoid receptor downregulation in the hippocampus after ELS, mTBI alone and mTBI + ELS. The combinatory insult of ELS and mTBI also impaired associative fear memory which was prevented with MCC950 treatment.
CONCLUSION: In summary, ELS limits recovery after mTBI by upregulating the expression of NLRP3 inflammasome signaling molecules in microglia. Inhibition of NLRP3 is an effective therapeutic for treating chronic cognitive deficits after ELS and mTBI.

Keywords:  Early life stress; Fluid-percussion brain injury; MCC950; Microglia; Traumatic brain injury

DOI:  https://doi.org/10.1186/s12974-025-03512-5
Cell Rep. 2025 Jul 14. pii: S2211-1247(25)00762-4. [Epub ahead of print]44(7): 115991

Physiological and injury-induced microglial dynamics across the lifespan.

Taryn Tieu, Anne-Jolene N Cruz, Jonathan R Weinstein, Andy Y Shih, Vanessa Coelho-Santos.

  Microglia are the brain's resident immune cells known for their dynamic responses to tissue and vascular injury. However, few studies have explored how microglial activity differs across the life stages of early development, adulthood, and aging. Using two-photon live imaging, we confirm that microglia in the adult cerebral cortex exhibit highly ramified processes and relatively immobile somata under basal conditions. Their responses to focal laser-induced injury occur over minutes and are highly coordinated among neighboring microglia. In contrast, neonatal microglia are denser and more mobile but less morphologically complex. Their responses to focal laser-induced injuries of capillaries or parenchymal tissue are uncoordinated, delayed, and persist over days. In the aged brain, microglia somata remain immobile under basal conditions, but their processes become less ramified. Their responses to focal injuries are coordinated but slower and less sensitive. These studies reveal the marked shifts in microglial morphology, distribution, dynamics, and injury response across the lifespan.

Keywords:  CP: Developmental biology; CP: Neuroscience; adulthood; aging; development; lifetime; live imaging; microglia; neuroimmune; surveillance; two-photon imaging; vascular

DOI:  https://doi.org/10.1016/j.celrep.2025.115991
Cell Rep. 2025 Jul 15. pii: S2211-1247(25)00783-1. [Epub ahead of print]44(8): 116012

The knockout of Moesin leads to excess microglia-mediated synaptic pruning and impairs social novelty in a mouse model.

Wanjing Lai, Junlin Chen, Hongyao Zhu, Yunbo Jiang, Yimei Niu, Qingpei Chen, Zhihua Luo, Yu Hu, Li Fang, Yaxuan Wang, Youqiang Song, Charlly Kao, Jubao Duan, Kwok-Fai So, Hakon Hakonarson, Li Zhang, Kai Wang, Lingling Shi.

  Genome-wide association studies (GWASs) have implicated a noncoding antisense RNA designated as MSNP1AS (Moesin pseudogene 1, antisense) in susceptibility to autism spectrum disorders (ASDs). MSNP1AS binds to and downregulates the Moesin (Msn) transcript and is highly overexpressed in the postmortem cerebral cortex of individuals with ASDs. However, the mechanistic link between Msn loss in vivo and ASD-related phenotypic traits remains enigmatic. Here, we generate Msn knockout (KO) mice, on which neurobehavioral tests reveal impaired social novelty and repetitive behaviors. Msn KO activates the microglial population, leading to aberrant C1q-dependent synaptic pruning followed by synaptic deficits in the medial prefrontal cortex. The aberrant regulatory pathway can be rescued by IFNAR1 antibody, which rescues microglial abnormalities and social deficits. Taken together, the results of the current study reveal a pathway in which Msn mediates interferon signaling and synaptic pruning to affect ASD-like behaviors, providing a functional genetic link between MSN and neurobehavioral abnormalities.

Keywords:  CP: Immunology; CP: Neuroscience; Moesin; interferon; medial prefrontal cortex; microglial cells; mouse; social behavior; synaptic pruning

DOI:  https://doi.org/10.1016/j.celrep.2025.116012
Elife. 2025 Jul 17. pii: RP105788. [Epub ahead of print]14

Pu.1/Spi1 dosage controls the turnover and maintenance of microglia in zebrafish and mammals.

Yi Wu, Weilin Guo, Haoyue Kuang, Xiaohai Wu, Thi Huong Trinh, Yuexin Wang, Shizheng Zhao, Zilong Wen, Tao Yu.

  Microglia are brain-resident macrophages playing pivotal roles in central nervous system (CNS) development and homeostasis. Yet, the cellular and molecular basis governing microglia maintenance remains largely unknown. Here, by utilizing a visible conditional knockout allele of pu.1/spi1b gene (the master regulator for microglia/macrophage lineage development) to generate mosaic microglia populations in adult zebrafish, we show that while pu.1-deficient microglia are immediately viable, they are less competitive, and chronically eliminated through Tp53-mediated cell competition. Interestingly, when conditionally inactivating Pu.1 in adult spi-b (the orthologue of mouse Spi-b) null mutants, microglia are rapidly depleted via apoptosis, suggesting that Pu.1 and Spi-b regulate microglia maintenance in a dosage-dependent manner. The dosage-dependent regulation of microglia maintenance by PU.1/SPI1 is evolutionarily conserved in mice, as shown by conditionally inactivating single and both Spi1 alleles in microglia, respectively. Collectively, our study reveals the conserved cellular and molecular mechanisms controlling microglia turnover and maintenance in teleosts and mammals.

Keywords:  cell competition; developmental biology; maintenance; microglia; mouse; pu.1 dosage; turnover; zebrafish

DOI:  https://doi.org/10.7554/eLife.105788
Phytomedicine. 2025 Jun 23. pii: S0944-7113(25)00648-8. [Epub ahead of print]145 157009

Jing An decoction alleviates neuroinflammation in Tourette syndrome by regulating butyrate-mediated microbiota-gut-brain axis.

Xiaoyu Kang, Enhao Cheng, Peixian Guo, Leying Xi, Chunjie Xiang, Shuo Xu, Yajie Zhang, Yuee Yang, Junfeng Zhang, Hongyan Long.

   BACKGROUND: Jing An decoction (JA), a traditional Chinese medicine formulation, has demonstrated notable clinical efficacy in the treatment of Tourette syndrome (TS) over the past two decades. The gut-brain axis (GBA) critically regulates neuroinflammation and neurodevelopmental processes, suggesting its potential as a therapeutic target in TS. However, the mechanisms by which JA alleviates TS via the GBA remain unclear.
PURPOSE: This study investigated gut microbiota and its metabolites to explore the potential mechanisms by which JA alleviates TS, a chronic neurodevelopmental disorder.
METHODS: A TS rat model was established via intraperitoneal injection of 3,3'-iminodipropionitrile (IDPN). Behavioral assessments, including stereotyped behavior, motor behavior, open-field testing, and novel object recognition, were conducted to evaluate the effect of JA. Gut microbiota was assessed by 16S rRNA sequencing, while short-chain fatty acids were quantified via GC-MS. Inflammatory cytokine levels were measured using ELISA. Gene expression related to tight junctions, key bacterial taxa, and metabolic enzymes was quantified using qPCR. Immunohistochemistry, immunofluorescence, and western blotting were employed to evaluate microglial polarization, barrier integrity, and the expression of key signaling pathway proteins. Additionally, an LPS-induced primary microglial inflammation model was used to investigate the role of butyrate in regulating microglia-mediated neuroinflammation.
RESULTS: JA significantly reduced stereotypic behaviors, hyperactivity, and cognitive impairments in TS rats. It restored gut microbiota diversity by increasing the abundance of butyrate-producing bacteria-particularly the Lachnospiraceae NK4A136 group-and upregulating the expression of butyrate-metabolizing enzymes (Buk and ButCOA). Butyrate levels in the colon and striatum were elevated in JA-treated rats, correlating with reduced neuroinflammation and enhanced intestinal and blood-brain barrier integrity. JA promoted M2 microglial polarization, suppressed HDAC3 expression, and inhibited the TLR4/NF-κB pathway. In primary microglial cells, butyrate attenuated LPS-induced neuroinflammation-an effect comparable to that of TLR4/NF-κB inhibitors (TAK-242, PDTC)-but this effect was reversed by an MCT1 inhibitor and HDAC3 activator (AZD3965, ITSA-1).
CONCLUSIONS: JA alleviates TS by regulating the GBA axis through butyrate-producing bacteria. Butyrate alleviates neuroinflammation by inhibiting the TLR4/HDAC3/NF-κB pathway, thereby promoting M2 microglial polarization.

Keywords:  Butyric acid; Gut microbiota; Gut-brain axis; Jing An decoction; Tourette syndrome

DOI:  https://doi.org/10.1016/j.phymed.2025.157009
J Neuroimmune Pharmacol. 2025 Jul 18. 20(1): 71

Activation of Hippocampal ACE2 Prevents the Dysbiosis-induced Depression-like Behavior in Mice by Enhanced Neurogenesis and Neuroprotection via Mas Receptor.

Kohei Takahashi, Osamu Nakagawasai, Kazuhiro Kurokawa, Kazuya Miyagawa, Atsumi Mochida-Saito, Hiroshi Takeda, Minoru Tsuji.

  The association between gut microbiota imbalance and depression is well known; however, its underlying mechanisms remain unclear. Angiotensin (Ang)-converting enzyme 2 (ACE2) transforms Ang II into Ang (1-7), which exerts antidepressant effects via the Mas receptor (MasR). However, the role of ACE2 in dysbiosis-related depression in the brain remains unclear. In this study, we assessed changes in brain ACE2 expression and whether diminazene aceturate (DIZE), an ACE2 activator, alleviates depression-like behavior in an antibiotic-induced (ABX) dysbiosis mouse model. The tail suspension test revealed depression-like behavior in ABX mice. Western blotting and immunohistochemistry revealed decreased expression levels of ACE2, Ang (1-7), p-CAMKII, p-CREB, BDNF, synaptophysin, p-PPARγ, CD206, TREM2, and IL-10 and reduced neurogenesis in the dentate gyrus of the hippocampus. Iba1, CD86, iNOS, IL-1β, TNF-α, and cleaved caspase-3 levels were increased, indicating microglial activation in the hippocampus. MasR staining was observed in neurons and microglia in the hippocampus of ABX mice. Furthermore, p-CAMKII and p-CREB staining was observed in neurons, while p-PPARγ staining was observed in microglia in the hippocampus of ABX mice treated with DIZE. DIZE administration prevented ABX-induced changes, whereas the effects of DIZE were abolished by co-administration with A779, a MasR inhibitor. These findings suggest that hippocampal ACE2 expression plays a crucial role in dysbiosis-related depression associated with gut microbiota imbalance, potentially offering a target for therapeutic interventions.

Keywords:  Angiotensin (1–7) [Ang (1–7)]; Angiotensin-converting Enzyme 2 (ACE2); Depression; Diminazene Aceturate (DIZE); Dysbiosis; Hippocampus

DOI:  https://doi.org/10.1007/s11481-025-10232-3
Glia. 2025 Jul 15.

Adrenergic Control of P2Y6 Receptor-Dependent Phagocytosis in Rodent and Human Microglia.

Thomas Deluc, Ariel Ase, Marie-France Dorion, Gilles Maussion, Yeman Tang, Rita T M Lo, Irina Shlaifer, Valerio E Piscopo, Thomas M Durcan, Stefano Stifani, Philippe Séguéla.

  Microglia, the resident immune cells of the central nervous system (CNS), are in constant survey of their environment. Extracellular nucleotides, released by stressed and damaged neurons, act as danger signals to microglia through various purinergic/pyrimidinergic receptors. In the CNS, the UDP receptor P2Y6 is mostly expressed in microglia, where its activation induces phagocytosis, a homeostatic function that is dysregulated in several neurodegenerative diseases and in chronic pain. Yet, modulatory mechanisms impacting P2Y6 activity remain to be identified. The microglial β2 adrenergic receptor (ADRB2) for norepinephrine represents a promising candidate for modulation of P2Y6 receptors. Our calcium imaging data indicate that exposure to the ADRB2 agonist isoproterenol inhibits the calcium transients evoked by activation of Gq-coupled P2Y6 receptors in primary mouse microglia. This functional modulation, suppressed by the selective ADRB2 antagonist ICI-118551, is conserved in human iPSC-derived microglia. Accordingly, we observed that the phagocytotic activity induced by P2Y6 is reduced by ADRB2 signaling in both mouse and human microglia. Finally, we report that ADRB2 activation is linked to a decrease in P2Y6 mRNA expression. These findings provide evidence that metabotropic and transcriptional crosstalks between nucleotide and adrenergic transductions control microglial responses in the CNS, potentially contributing to the pathophysiology of neuro-immune disorders and chronic pain conditions.

Keywords:  calcium; chronic pain; microglia; norepinephrine; phagocytosis; purinergic receptors

DOI:  https://doi.org/10.1002/glia.70054
Regen Ther. 2025 Dec;30 259-267

Human iPSC-derived cerebral organoids reveal oxytocin-mediated protection against amyloid-β pathology.

Tomoki Asaba, Sayuri Hamano, Ayaka Nanmo, Jieun Seo, Tatsuto Kageyama, Junji Fukuda.

   Introduction: Neuroinflammation is a key contributor to the pathogenesis of Alzheimer's disease (AD), and impaired clearance of amyloid-β (Aβ) by microglia is closely associated with disease progression. Oxytocin (OXT), a hypothalamic neuropeptide, has recently been reported to exert anti-inflammatory effects on microglia; however, its therapeutic potential in the human brain remains unclear.
Methods: We generated human cerebral organoids (hCOs) from induced pluripotent stem cells (iPSCs) to model early AD-like pathology. Aβ toxicity was induced by applying 3 μM Aβ1-42 for 48 h. The protective effects of OXT were evaluated through immunohistochemistry, RT-qPCR, calcium imaging, and multielectrode array (MEA) recordings. The involvement of microglia in Aβ clearance was assessed by immunostaining and gene expression analysis of TREM2.
Results: Aβ exposure led to significant deposition of Aβ in the outer layers of hCOs, accompanied by suppressed neural activity and increased apoptotic signaling. Pretreatment with OXT attenuated Aβ deposition and caspase-3-mediated apoptosis in a concentration-dependent manner. OXT also restored calcium oscillations and neuronal network activity as measured by MEA. Notably, OXT enhanced the recruitment of microglia to Aβ deposits and upregulated the expression of TREM2, a key regulator of microglial phagocytosis. Co-expression of oxytocin receptors (OXTR) on Iba1-positive microglia suggests that OXT directly modulates microglial activation and Aβ clearance.
Conclusions: OXT has neuroprotective effects on human cortical organoids by preserving their neuronal activity and promoting microglial-mediated Aβ clearance. This study provides novel insights into the therapeutic potential of OXT for targeting neuroinflammation and Aβ pathology in patients with AD.

Keywords:  Alzheimer's disease; Amyloid-beta; Anti-inflammatory signaling; Cerebral organoids; Microglia; Oxytocin

DOI:  https://doi.org/10.1016/j.reth.2025.06.013
Front Cell Neurosci. 2025 ;19 1623755

Sialylation as a checkpoint for inflammatory and complement-related retinal diseases.

Yiduo Min, German Cuevas-Rios, Thomas Langmann, Harald Neumann.

  Sialylation is a modification process involving the addition of sialic acid residues to the termini of glycoproteins and glycolipids in mammalian cells. Sialylation serves as a crucial checkpoint inhibitor of the complement and immune systems, particularly within the central nervous system (CNS), including the retina. Complement factor H (FH), complement factor properdin (FP), and sialic acid-binding immunoglobulin-like lectin (SIGLEC) receptors of retinal mononuclear phagocytes are key players in regulating the complement and innate immune systems in the retina by recognizing sialic acid (Sia) residues. Intact retinal sialylation prevents any long-lasting and excessive complement or immune activation in the retina. However, sialylated glycolipids are reduced in the CNS with aging, potentially contributing to chronic inflammatory processes in the retina. Particularly, genetically induced hyposialylation in mice leads to age-related, complement factor C3-mediated retinal inflammation and bipolar cell loss. Notably, most of the gene transcript pathways enriched in the mouse retina, following genetically induced hyposialylation, are also involved in age-related macular degeneration (AMD). Interestingly, intravitreal application of polysialic acid (polySia) controlled the innate immune responses in the mouse retina by blocking mononuclear phagocyte reactivity, inhibiting complement activation, and protecting against vascular damage in two different humanized SIGLEC-11 animal models. Accordingly, a polySia polymer conjugate has entered clinical phase II/III testing in patients with geographic atrophy secondary to AMD. Thus, hyposialylation or dysfunctional sialylation should be considered as an age-related contributor to inflammatory retinal diseases, such as AMD. Consequently, sialic acid-based biologics could provide novel therapies for complement-related retinal diseases.

Keywords:  age-related macular degeneration (AMD); complement; inflammation; microglia; polysialic acid; retina; sialic acid; sialylation

DOI:  https://doi.org/10.3389/fncel.2025.1623755
Front Endocrinol (Lausanne). 2025 ;16 1609796

Interleukin-4 prevents increased endothelial permeability by inducing pericyte survival and modulating microglial responses in diabetic retinopathy.

Jang-Hyuk Yun.

   Introduction: Retinal vascular leakage due to increased endothelial permeability is a major contributor to the pathogenesis of diabetic retinopathy (DR) and visual impairment. Pericyte loss and microglia-mediated inflammation exacerbate this vascular dysfunction. Interleukin-4 (IL-4) is known for its anti-inflammatory and tissue-protective properties, but its role in DR remains unclear.
Methods: We evaluated IL-4 expression and signaling in the retinas of streptozotocin-induced diabetic mice. In vitro assays were conducted under high-glucose and TNF-α conditions using retinal endothelial cells, pericytes, and microglia to assess IL-4's effects on barrier function, cell viability, and inflammatory state. Pathway-specific analyses were performed to investigate PI3K/AKT and STAT6 signaling.
Results: IL-4 expression and downstream signaling were significantly reduced in diabetic retinas. IL-4 promoted pericyte survival via PI3K/AKT activation and modulated microglial functional profiles through STAT6 signaling, favoring an anti-inflammatory phenotype. These effects contributed to restored endothelial barrier integrity and tight junction protein expression under diabetic stress conditions in vitro.
Conclusion: IL-4 supports retinal vascular stabilization in DR by preserving pericyte viability and modulating microglial activity. These findings highlight IL-4 as a potential therapeutic target for preventing or slowing DR progression and warrant further preclinical investigation.

Keywords:  diabetic retinopathy; endothelial permeability; interleukin-4; microglia functional states; pericytes; signal transducer and activator of transcription 6

DOI:  https://doi.org/10.3389/fendo.2025.1609796
Neurochem Res. 2025 Jul 17. 50(4): 235

Novel GLP-1/GIP Dual Receptor Agonist Alleviates Neonatal Hypoxic-Ischemic Encephalopathy by Inhibiting TLR2/NF-κB/NLRP3 Mediated-Neuroinflammation : The role of DA5-CH in neonatal hypoxic-ischemic encephalopathy.

Weiqing Huang, Xionghui Wu, Shuting Chang, Xiaoming Peng, Xiao Li.

  Hypoxic-ischemic encephalopathy (HIE) is an irreversible brain injury attributable to impaired blood oxygen delivery in the brain after perinatal asphyxia. The pathogeny of HIE is very complex, and there is still shortage of effective treatment. DA5-CH is a novel dual receptor agonist of glucose dependent insulin stimulating polypeptide (GIP) and glucagon like peptide-1 (GLP-1). However, the function and mechanism of DA5-CH in HIE remain unclear. In this paper, cultured cortical neurons were exposed to oxygen-glucose deprivation (OGD) and neonatal rats were subjected to hypoxic-ischemic damage to explore the protective effects of DA5-CH. Our work revealed that DA5-CH markedly increased cell viability, reduced intracellular ROS levels and DNA damage, and decreased cell apoptosis in OGD-treated cultured cortical neurons. In vivo, DA5-CH treatment significantly improved cognitive dysfunction and neuronal damage, decreased the infarct volume and neuronal death of hypoxic-ischemic (HI) neonatal rats. In addition, DA5-CH decreased TNFα, IL-1β and IL-6 levels in cortical tissue of HI neonatal rats and in microglia cells subjected to OGD. Moreover, DA5-CH treated microglia medium increased the cell viability, but decreased apoptosis of cortical neurons. DA5-CH suppressed NLRP3 inflammasome activation through inactivation of the TLR2/NF-κB signalling pathway. Furthermore, the protective effects of DA5-CH on the hypoxic-ischemic brain injury were antagonized by nigericin (an NLRP3 agonist). Taken together, our findings revealed that DA5-CH alleviates neonatal hypoxic-ischemic encephalopathy by inhibiting TLR2/NF-κB/NLRP3 mediated-neuroinflammation.

Keywords:  DA5-CH; Dual receptor agonist; Hypoxic-ischemic encephalopathy; NLRP3; Neuroinflammation

DOI:  https://doi.org/10.1007/s11064-025-04475-y
Brain Res Bull. 2025 Jul 11. pii: S0361-9230(25)00274-6. [Epub ahead of print] 111462

Environmental enrichment attenuates social isolation-exacerbated postoperative cognitive dysfunction in aged mice via inhibition of RAGE-HMGB1 proinflammatory signaling.

Sha Li, Hongyan Wang, Mingzhe Qin, Wei Huang, Huifang Gao, Xiaoyang Song, Xiaolong Chen, Bixi Li.

  Microglial overactivation, leading to neuroinflammation, plays a pivotal role in the development of postoperative cognitive dysfunction (POCD). However, the reasons behind varying inflammatory and cognitive reactions to similar surgical stresses among individuals remain enigmatic. Social isolation (SI), a prevalent psychosocial stressor among older adults, is known to intensify neuroinflammatory reactions and may represent a crucial but overlooked risk factor for POCD. Utilizing aged mouse models, our study reveals that four weeks of preoperative SI considerably worsens surgical-related cognitive deficits, specifically affecting spatial memory (evident from increased Barnes maze latency) and recognition memory (manifested by decreased novel object preference). From a mechanistic perspective, SI predominantly boosts HMGB1-RAGE signaling (rather than TLR4), leading to M1 microglial activation (marked by elevated iNOS and CD86 levels), synaptic destabilization (indicated by decreased PSD95 and SYN), and elevated proinflammatory cytokines. Genetic downregulation of RAGE reverses these alterations, whereas environmental enrichment (EE) offers neuroprotective effects by specifically blocking the RAGE-HMGB1 pathway. Notably, RAGE overexpression negates the beneficial effects of EE, emphasizing the key role of this receptor in SI-induced susceptibility to POCD. Our findings experimentally demonstrate that SI predisposes individuals to POCD via RAGE-dependent neuroinflammatory priming and suggest EE as a potential targeted intervention. These results could inform tailored preventative measures for elderly surgical patients at risk.

Keywords:  Environmental enrichment; Neuroinflammation; Postoperative cognitive dysfunction; RAGE-HMGB1 axis; Social isolation

DOI:  https://doi.org/10.1016/j.brainresbull.2025.111462
Biomed Opt Express. 2025 Jun 01. 16(6): 2365-2375

High-resolution multimodal visible light optical coherence tomography and scanning laser ophthalmoscopy for in vivo neuronal and vascular retinal imaging in mice.

Siyu Song, Guangru Ben Liang, Tristan T Hormel, Yukun Guo, Min Gao, Benjamin Sivyer, J Peter Campbell, Siyu Chen, Yifan Jian, Yali Jia.

Microglial cells play a crucial role in retinal vascular and brain diseases through complex interactions with blood vessels and neurons. To image retinal structures, vasculature, and microglia, we developed a multimodal system integrating visible light optical coherence tomography (vis-OCT) and scanning laser ophthalmoscopy (SLO). Both subsystems achieve micron-scale resolutions and operate within the diffraction limit across a 34-degree field of view: theoretically, the OCT system offers an axial resolution of 2.12 μm and a transverse resolution of 8.78 μm, while the SLO system provides a transverse resolution of 7.1 μm. We validated the system performance using transgenic mice with fluorescent protein-labeled microglia, revealing detailed retinal microstructures, microvasculature, and individual microglia with distinguishable branches, confirmed by ex vivo microscopy.

DOI: https://doi.org/10.1364/BOE.560539
bioRxiv. 2025 Jun 25. pii: 2025.06.23.661190. [Epub ahead of print]

Tau endo-lysosomal processing in human iPSC-derived microglia is impacted by tau aggregation state, but not by microglial activation status.

Andrew Shultz, Anna Vincze, Todd T Yau, Emma L Poirier, Jennifer N Rauch.

Microglia are the tissue resident macrophages of the brain and their contribution to tau pathology progression remains to be fully understood. In this study, we developed a quantitative platform to elucidate the endo- lysosomal regulation of tau within human induced pluripotent stem cell (iPSC)-derived microglia. We show that iPSC-derived microglia internalize monomeric and fibrillar tau through different cellular mechanisms and with different degradation kinetics. Acute inflammatory activation of microglia alters tau endocytosis, but surprisingly does not impact lysosomal clearance. These results highlight the importance of the microglial endo-lysosome system as a regulator of tau pathology that is decoupled from acute microglial activation.
Highlights: Human iPSC-derived microglia endocytose tau using different cellular mechanismsNanoBiT system can measure tau endocytosis/degradation in iPSC-derived microgliaAggregation of tau impacts the rate of lysosomal degradation after endocytosisAcute inflammation affects total endocytosed tau, but not degradation in microglia.

DOI: https://doi.org/10.1101/2025.06.23.661190
bioRxiv. 2025 Jun 15. pii: 2025.06.12.659424. [Epub ahead of print]

Inhibition of Acyl-CoA: Cholesterol Acyltransferase 1 Promotes Shedding of Soluble TREM2 and LRP1-Dependent Phagocytosis of Amyloid β Protein in Microglia.

Moriah J Hovde, Anna Maaser-Hecker, Rudolph E Tanzi.

Lipid regulation plays a major role in the pathogenesis of Alzheimer's disease (AD). In AD patients and transgenic mice, microglia exhibit increased expression of SOAT1 , encoding Acyl-CoA: Cholesterol Acyltransferase 1 (ACAT1), which catalyzes the production of cholesteryl esters in lipid droplets. ACAT1 Inhibition has been reported to reduce β-amyloid pathology. However, the molecular mechanism underlying this effect remains unknown. Here, we show ACAT1 inhibition in mouse and human iPSC- derived microglia upregulates LRP1 levels and shedding of soluble TREM2 (sTREM2) owing to enhanced cleavage of TREM2 by ADAM10/17. Knocking out TREM2 or preventing sTREM2 release abrogated the ability of ACAT1 inhibition to enhance microglial uptake of amyloid β (Aβ). This could be rescued by the addition of recombinant sTREM2, but only in the presence of LRP1. Collectively, these data indicate ACAT1 inhibition increases microglial uptake of Aβ in a sTREM2- and LRP1-dependent manner suggesting new avenues for treating and preventing AD.

DOI: https://doi.org/10.1101/2025.06.12.659424
bioRxiv. 2025 Jun 25. pii: 2025.06.19.660619. [Epub ahead of print]

Identification of Chlamydia pneumoniae and NLRP3 inflammasome activation in Alzheimer's disease retina.

Bhakta Prasad Gaire, Yosef Koronyo, Jean-Philippe Vit, Alexandre Hutton, Natalie Swerdlow, Dieu-Trang Fuchs, Altan Rentsendorj, Saba Shahin, Lalita Subedi, Edward Robinson, Alexander V Ljubimov, Lon S Schneider, Debra Hawes, Stuart L Graham, Vivek K Gupta, Mehdi Mirzaei, Keith L Black, Jesse G Meyer, Moshe Arditi, Timothy R Crother, Maya Koronyo-Hamaoui.

Chlamydia pneumoniae (Cp), an obligate intracellular bacterium, has been implicated in Alzheimer's disease (AD), yet its role in retinal pathology remains unexplored. We analyzed postmortem tissues from 95 human donors and found 2.9-4.1-fold increases in Cp inclusions in AD retinas and brains, with no significant elevation in mild cognitive impairment (MCI). Proteomics revealed dysregulation of retinal and brain bacterial infection-related proteins and NLRP3 inflammasome pathways. NLRP3 expression was markedly elevated in MCI and AD retinas, and its activation was evident by increased N-terminal gasdermin D (NGSDMD) and mature interleukin-1β. Retinal Cp strongly correlated with Aβ 42 and NLRP3 inflammasome components, which tightly linked to cleaved caspase-3-apoptotic and NGSDMD-pyroptotic cell death. Although retinal microgliosis was elevated in AD, Cp-associated microglia were reduced by 62%, suggesting impaired Cp phagocytosis. Higher retinal Cp burden correlated with APOEε4, Braak stage, and cognitive deficit. Machine learning identified retinal Cp or NLRP3 combined with Aβ 42 as strong predictors of AD diagnosis, staging, and cognitive impairment. Our findings suggest that Cp infection contributes to AD dementia but not initiating pathology, whereas early NLRP3 activation may promote disease development, warranting studies on Cp's role in AD pathogenesis and early antibiotic or inflammasome-targeted therapies.

DOI: https://doi.org/10.1101/2025.06.19.660619
bioRxiv. 2025 May 09. pii: 2025.05.08.652864. [Epub ahead of print]

APOE genotype confers context dependent neurovascular vulnerability in immune-vascularized human forebrain organoids.

Haohui Fang, Xiangyu Liao, C Korin Bullen, Ruoyan Pu, Hu Wang, Juliana Condoleo, Sueanne Cheat, Xueyi Chen, Yanjun Zhang, Sonya Zhang, Da Huo, Kadia Lissit, Alina Yang, Kateri Jarvis, Stewart Neifert, Yuejia Huang, William Bishai, Sanjay K Jain, Ted Dawson, Valina L Dawson, Jinchong Xu.

The APOE gene is a major genetic determinant of neurovascular and immune function, yet the mechanisms by which its isoforms modulate brain vulnerability to pathogenic stress remain incompletely understood. Here, we employ isogenic human iPSC-derived immune vascularized Forebrain Organoid-based Multicellular Assembled Cerebral Organoids (FORMA COs) to dissect isoform-specific responses to a clinically relevant viral challenge. We find that APOE2 and APOE4 FORMA-COs exhibit heightened viral RNA burden and distinct neuroinflammatory profiles compared to APOE3. Specifically, APOE4 promotes IL-1α and VEGFA induction, whereas APOE2 leads to elevated TNFβ and VEGFA protein accumulation, indicating divergent pathways of injury. Integrated transcriptomic analyses, combined with known and predicted APOE protein protein interaction networks, reveal genotype dependent enrichment of cytokine signaling, angiogenic remodeling, and immune dysregulation. In vivo validation using humanized mouse models corroborates APOE genotype specific vascular remodeling, microglial activation, and oligodendrocyte perturbation. These findings demonstrate that APOE genotype confers context-specific susceptibility to neuroimmune and vascular injury, providing insight into genetic risk mechanisms underlying infection-related and neurodegenerative brain disorders.

DOI: https://doi.org/10.1101/2025.05.08.652864
Res Sq. 2025 Jun 26. pii: rs.3.rs-6658954. [Epub ahead of print]

Identification of Chlamydia pneumoniae and NLRP3 inflammasome activation in Alzheimer's disease retina.

Maya Koronyo-Hamaoui, Bhakta Prasad Gaire, Yosef Koronyo, Jean-Philippe Vit, Alexandre Hutton, Natalie Swerdlow, Edward Robinson, Dieu-Trang Fuchs, Altan Rentsendorj, Lalita Subedi, Alexander Ljubimov, Lon S Schneider, Debra Hawes, Stuart Graham, Vivek Gupta, Mehdi Mirzaei, Keith Black, Jesse G Meyer, Moshe Arditi, Timothy Crother.

Emerging evidence implicates bacterial infections, including Chlamydia pneumoniae (Cp), a gram-negative obligate intracellular bacterium responsible for community-acquired pneumonia, in Alzheimer's disease (AD) pathogenesis. However, the involvement of Cp in early and advanced AD in the retina is unknown. Here, we identified the existence and distribution of intracellular Cp inclusions and related NLRP3 inflammasome activation and neurodegeneration in postmortem retinas and brains from 95 human donors. Histological analysis in neuropathologically-confirmed MCI and AD patients compared with cognitively normal individuals (n=70), revealed 2.9-4.1-fold increases of Cp inclusions in AD retinas and brains, respectively, with no significant increases in MCI retinas or brains. Mass spectrometry-based proteomics in additional cohorts (n=30), revealed dysregulated brain and retinal bacterial infection-related proteins and inflammasome-associated pathways. Retinal Cp was strongly linked to Aβ 42 , caspase-1 and NLRP3-inflammasome activation components, as well as cleaved caspase-3 + apoptosis and cleaved gasdermin D pyroptotic cell death. Despite increased IBA1 + microgliosis in the AD retina, the Cp-associated microglial population was reduced by 62%, suggesting impaired microglial phagocytosis. Higher retinal Cp burden correlated with APOEε4 status, advanced Braak stage, and cognitive decline. Machine learning models revealed that retinal Cp or NLRP3, in combination with retinal Aβ 42 , effectively predicted AD diagnosis, Braak stage, and cognition. These findings suggest that Cp infection contributes to AD dementia but is unlikely to initiate AD pathological changes, whereas elevated retinal NLRP3 may serve as an early AD marker. These results underscore the need for future studies investigating Cp's role in AD dementia and testing early antibiotic or inflammasome-targeting therapies.

DOI: https://doi.org/10.21203/rs.3.rs-6658954/v1
BMC Neurosci. 2025 Jul 17. 26(1): 43

Post-stroke butyrate treatment shows sex-dependent microglial responses but does not improve outcomes in a mouse model of endothelin-1 sensory motor stroke.

Ashley de Witte, Juliana Montoya Sanchez, Emerson Daniele, Jingan Chen, Yibang Fan, Pranav Khatri, Daniela Lozano Casasbuenas, Angel Zhang, Kathryn G Todd, Maryam Faiz, Matthew Churchward.

   BACKGROUND: Stroke induces gut dysbiosis and reduces microbial production of short-chain carboxylic acids (SCCAs), which negatively correlates with stroke outcomes. Previous studies have demonstrated that SCCA supplementation can improve functional recovery, with one recent study suggesting this occurs via modulation of microglial responses. However, the effects of individual SCCAs on microglial responses remain unclear, particularly across sexes and following a more clinically relevant, post-stroke treatment protocol. To address this gap, we investigated the effect of post-stroke supplementation with butyrate on stroke outcomes and microglial responses in both male and female mice over time.
RESULTS: Post-stroke butyrate treatment produced sex-specific microglial responses. In females, butyrate increased microglial ramification at chronic timepoints in vivo and enhanced IL6 release following IFNγ stimulation in vitro. These microglial changes were not observed in males. Despite the distinct microglial responses, butyrate treatment did not correlate with improved stroke outcomes in either sex, as measured by lesion volume and functional recovery.
CONCLUSIONS: Our findings reveal previously unknown sex differences in microglial responses to butyrate following stroke. Despite these microglial changes in females, butyrate treatment did not improve functional outcomes in either sex, suggesting that sex-specific optimization of dosing and delivery may be needed for therapeutic efficacy.

Keywords:  Butyrate; Gut-brain axis; Ischemic stroke; Microglia; Sex differences; Short-chain carboxylic acids (SCCAs); Short-chain fatty acids (SCFAs); Stroke

DOI:  https://doi.org/10.1186/s12868-025-00959-3
STAR Protoc. 2025 Jul 10. pii: S2666-1667(25)00342-9. [Epub ahead of print]6(3): 103936

Protocol to assess engulfment and degradation of synaptosomes by murine microglia in vitro.

Alessandro Matera, Anne-Claire Compagnion, Rosa Chiara Paolicelli.

  Microglia, the innate immune cells of the central nervous system, refine neuronal circuitries both during brain development and in neurodegenerative diseases. Here, we present a protocol to independently assess the engulfment and degradation of synaptosomes by murine microglia, both in fixed and live samples, using confocal imaging. We describe steps for isolating primary microglia, preparing and conjugating synaptosomes with pHrodo, and performing an uptake and degradation assay. We then detail procedures for analyzing synaptosome uptake and degradation using ImageJ software. For complete details on the use and execution of this protocol, please refer to Matera, Compagnion, et al.1.

Keywords:  Cell culture; Microscopy; Neuroscience

DOI:  https://doi.org/10.1016/j.xpro.2025.103936
STAR Protoc. 2025 Jul 15. pii: S2666-1667(25)00252-7. [Epub ahead of print]6(3): 103846

Protocol for performing and analyzing a live-cell imaging-based microglia phagocytosis assay using AI on the Olympus ScanR system.

Alexander Zähringer, Janaki Manoja Vinnakota, Tobias Wertheimer, Marie Follo, Robert Zeiser.

  Various neurological disorders show dysregulation of microglial function, including phagocytosis, necessitating accurate and efficient analysis. Here, we present a protocol using our custom-trained neural network (AIstain) in the Olympus ScanR environment for easy-to-use workflows of microglial phagocytosis assays. We describe steps for preparing microglia and setting up the microscope. We then explain the workflow of live-cell imaging and usage of AI in the data analysis. This protocol facilitates the preparation of phagocytosis assays and improves accuracy in data analysis. For complete details on the use and execution of this protocol, please refer to Zähringer et al.1.

Keywords:  Cancer; Health Sciences; Microscopy; Neuroscience

DOI:  https://doi.org/10.1016/j.xpro.2025.103846