Modulation of C5a-C5aR1 signaling alters the dynamics of AD progression.
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ABSTRACT:
PROVIDER: PRJNA811136 | ENA |
REPOSITORIES: ENA
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Project description:The complement system is part of the innate immune system that works to clear pathogens and cellular debris. In the central nervous system (CNS) complement activation can promote synaptic pruning clearance of neuronal blebs recruitment of phagocytes and protection from pathogens. However in a neuropathologic environment complement activation may contribute to inflammatory pathways neuronal dysfunction and in the Alzheimer’s disease (AD) brain cognitive decline. If complement activation proceeds to the cleavage of C5 and thus generation of C5a engagement of C5a with the receptor C5aR1 can instigate a feed-forward loop of inflammation injury and neuronal death thus making this molecule a potential target for modulation in AD therapeutics. The Arctic (Arc) AD mouse model known to rapidly accumulate fibrillar amyloid plaques was crossed to a model that lacks the receptor for C5a (ArcC5aR1KO) or to a transgenic mouse that generates C5a under the GFAP promoter (ArcC5a+). ArcticC5a+ mice showed accelerated loss of spatial memory compared to Arc mice. While eliminating C5aR1 did not alter amyloid plaque accumulation in this AD model C5aR1KO delayed or prevented the expression of important AD-associated genes in the hippocampus indicating a separation between those genes induced by amyloid plaques and those influenced by C5a-C5aR1 signaling. C5ar1 deletion also reduced/delayed the expression of select pan-reactive and A1 reactive astrocyte genes. ArcC5aR1KO showed delayed expression of genes enriched for biological processes that are significant in the AD context such as regulation of inflammatory signaling microglial cell activation astrocyte migration and lysosome pathway. Interestingly overexpression of C5a also delayed the increase of some AD- complement and astrocyte-associated genes perhaps mediated by C5aR2 and emphasizing the importance of selectively suppressing C5aR1. Immunohistochemical investigation further confirmed that modulation of C5a-C5aR1 either delayed or reduced some reactive microglial markers in the Arc hippocampus including CD11b and CD11c. These results suggest that C5a-C5aR1 signaling in the context of AD largely exerts its effects by suppressing those microglial activation pathways that accelerate disease enhancing pathways. Given the highly focused modulation of a common driver of neurotoxicity pharmacological inhibition of this C5aR1 signaling pathway is a promising therapeutic strategy to treat AD.
2022-03-05 | GSE197591 | GEO
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Project description:The anaphylatoxin C5a is a potent mediator of innate immunity and promotes inflammation via its receptor C5aR1 upon complement system activation danger-associated molecular patterns. Both C5a and C5aR1 are thought to be contributing factors in inflammatory and infectious conditions of the bone. Bone fracture healing, for example, was significantly improved when applying a C5aR1-antagonist in a rodent model of severe systemic inflammation and osteoblasts were found to be target cells for C5a in this setting. Interestingly, osteoblasts up-regulate C5aR1 during osteogenic differentiation and after bone injury. Further, C5a induces inflammatory cytokines, such as IL-6, and the osteoclastogenic mediator RANKL in osteoblasts. However, the molecular mechanisms underlying C5a-C5aR1 signaling axis in osteoblasts remain unclear, and further targets of C5a are still elusive. Using microarray analysis, we analyzed intracellular events following C5aR1 activation in osteoblasts and defined up- or down-regulated genes and their belonging biological pathways.
2018-12-26 | GSE107036 | GEO
Project description:In this project, we aimed to examine gene expression changes in intestinal organoids treated with the complement C5a receptor 1 (C5aR1) antagonist PMX205 either with or without irradiation. Intestinal organoids from wild-type C57BL/6 mice were cultured and plated. The following day, the media was supplemented with 5 μg/ml of PMX205 or a vehicle control, and after one hour, organoids were subjected to either 0 Gy or 9 Gy of radiation. Samples were collected after 24 and 48 hours, and RNA was extracted and processed for RNA sequencing.
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Project description:In mice, complement C5a and its receptor C5aR1 elicit systemic and local inflammation and drive tissue injury in diabetic kidney disease via altered metabolic flexibility, which can be attenuated by therapy with a specific orally active inhibitor of C5aR1.
2019-07-01 | GSE118089 | GEO
Project description:C5aR1, a receptor for the complement activation proinflammatory fragment, C5a, is primarily expressed on cells of the myeloid lineage, and to a lesser extent on endothelial cells and neurons in brain. Previous work demonstrated C5aR1 antagonist, PMX205, decreased amyloid pathology and suppressed cognitive deficits in Alzheimer Disease (AD) mouse models. In the Arctic AD mouse model, genetic deletion of C5aR1 prevented behavior deficits at 10 months. However, the molecular mechanisms of this protection has not been definitively demonstrated. To understand the role of microglial C5aR1 in the Arctic AD mouse model, we have taken advantage of the CX3CR1GFP and CCR2RFP reporter mice to distinguish microglia as GFP-positive and infiltrating monocytes as GFP and RFP positive, for subsequent transcriptome analysis on specifically sorted myeloid populations from wild type and AD mouse models. Immunohistochemical analysis of mice aged to 2, 5, 7 and 10 months showed no change in amyloid beta (Ab) deposition in the Arctic C5aR1 knockout (KO) mice relative to that seen in the Arctic mice. Of importance, no CCR2+ monocytes/macrophages were found near the plaques in the Arctic brain with or without C5aR1. RNA-seq analysis on microglia from these mice identified inflammation related genes as differentially expressed, with increased expression in the Arctic mice relative to wildtype and decreased expression in the Arctic/C5aR1KO relative to Arctic. In addition, phagosomal-lysosomal proteins and protein degradation pathways that were increased in the Arctic mice were further increased in the Arctic/C5aR1KO mice. These data are consistent with a microglial polarization state with restricted induction of inflammatory genes and enhancement of clearance pathways.
2017-10-10 | GSE93824 | GEO
Project description:In the K14-HPV16 transgenic mouse model of squamous carcinogenesis, activation of C5a receptor (C5aR1) in early neoplastic tissues fosters protumorigenic properties of C5aR1+ mast cells and macrophages, and in turn, suppression of CD8+ T cell cytotoxicity. Therapeutic inhibition of C5a receptor (C5aR1) with a peptide antagonist improved efficacy to paclitaxel chemotherapy associated with CXCR3-dependent CD8+ T cell activation. To investigate the effects of combination therapy on the T cell repertoire, we performed deep sequencing of the complementarity-determining region (CDR) 3 of the T cell receptor (TCR)b chain in matched tumor lysates and peripheral blood mononuclear cells (PBMCs). Intratumoral TCRβ clonotypes were hyperexpanded and increasingly detected in matched peripherally-expanded T cell populations, thereby implicating antigen-dependent peripheral priming in response to systemic C5aR1 inhibition.
2018-11-28 | GSE112322 | GEO
Project description:In the K14-HPV16 transgenic mouse model of squamous carcinogenesis, activation of C5a receptor (C5aR1) in early neoplastic tissues fosters protumorigenic properties of C5aR1+ mast cells and macrophages, and in turn, suppression of CD8+ T cell cytotoxicity. Therapeutic inhibition of C5a receptor (C5aR1) with a peptide antagonist improved efficacy to paclitaxel chemotherapy associated with CXCR3-dependent CD8+ T cell activation. To investigate the effects of combination therapy on the T cell repertoire, we performed deep sequencing of the complementarity-determining region (CDR) 3 of the T cell receptor (TCR)b chain in matched tumor lysates and peripheral blood mononuclear cells (PBMCs). Intratumoral TCRβ clonotypes were hyperexpanded and increasingly detected in matched peripherally-expanded T cell populations, thereby implicating antigen-dependent peripheral priming in response to systemic C5aR1 inhibition.
2018-11-28 | GSE112321 | GEO
Project description:Despite the discovery of PMX205 more than 20 years ago and its reported beneficial effects in Alzheimer’s disease, the specific mechanism that might be driving the improvement in cognition are still not know. Here, we used the Tg2576 mouse model of Alzheimer’s disease and treated them with PMX205 at the onset of the amyloid pathology to further determine the effects of this C5aR1 antagonist on microglial cells. The results presented in this study demonstrated a neuroprotective effect of PMX205, which rescues the excessive synaptic pruning and synapse loss associated with Alzheimer’s disease. This finding seems to be linked to the reduction of a unique microglial subpopulation associated to synaptic pruning in the PMX205 treated mice. Interestingly, we also show here that blocking C5a-C5aR1 signaling in the Tg2576 mouse model of AD results in the increase of the DAM2 microglial subpopulation, suggesting that PMX205 might be inducing a disease mitigating phenotype on microglial cells. Our data further supports the use of C5aR1 antagonists as potential therapeutic targets to treat or slow the progression of Alzheimer’s disease.
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Project description:Systemic candidiasis is a common, high-mortality, nosocomial fungal infection. Unexpectedly, it has emerged as a complication of anti-complement C5-targeted monoclonal antibody treatment, indicating a critical niche for C5 in antifungal immunity. We identified transcription of complement system genes as the top biological pathway induced in candidemic patients and as predictive of candidemia. Mechanistically, C5a-C5aR1 promoted fungal clearance and host survival in a mouse model of systemic candidiasis by stimulating phagocyte effector function and ERK- and AKT-dependent survival in infected tissues. C5ar1 ablation rewired macrophage metabolism downstream of mTOR, promoting their apoptosis and enhancing mortality through kidney injury. Besides hepatocyte-derived C5, local C5 produced intrinsically by phagocytes provided a key substrate for antifungal protection. Lower serum C5a concentrations or a C5 polymorphism that decreases leukocyte C5 expression correlated independently with poor patient outcomes. Thus, local, phagocyte-derived C5 production licenses phagocyte antimicrobial function and confers innate protection during systemic fungal infection.
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