Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA278645 | ENA |
REPOSITORIES: ENA
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Project description:The efficiency of central nervous system (CNS) remyelination declines with age. This is in part due to an age-associated decline in the phagocytic removal of myelin debris, which contains inhibitors of oligodendrocyte progenitor cell differentiation. In this study we show that expression of genes involved in the retinoid X receptor (RXR) pathway are decreased with aging in myelin-phagocytosing cells. Loss of RXR function in young macrophages mimics aging by delaying remyelination after experimentally-induced demyelination, while RXR agonists partially restore myelin debris phagocytosis in aged macrophages. The FDA-approved RXR agonist bexarotene, when used in concentrations achievable in human subjects, caused a reversion of the gene expression profile in aging human monocytes to a more youthful profile. These results reveal the RXR pathway as a positive regulator of myelin debris clearance and a key player in the age-related decline in remyelination that may be targeted by available or newly-developed therapeutics. 24 Human CD14+ monocyte-sorted PBMC samples representing 4 Healthy Volunteers (HV) and 4 Multiple Sclerosis (MS) patients under 3 different treatment conditions. Condition 1 = (-) Phagocystosis (-) Bexarotene. Condition 2 = (+) Phagocystosis (-) Bexarotene. Condition 3 = (+) Phagocystosis (+) Bexarotene.
2015-11-04 | E-GEOD-66988 | biostudies-arrayexpress
Project description:The efficiency of central nervous system (CNS) remyelination declines with age. This is in part due to an age-associated decline in the phagocytic removal of myelin debris, which contains inhibitors of oligodendrocyte progenitor cell differentiation. In this study we show that expression of genes involved in the retinoid X receptor (RXR) pathway are decreased with aging in myelin-phagocytosing cells. Loss of RXR function in young macrophages mimics aging by delaying remyelination after experimentally-induced demyelination, while RXR agonists partially restore myelin debris phagocytosis in aged macrophages. The FDA-approved RXR agonist bexarotene, when used in concentrations achievable in human subjects, caused a reversion of the gene expression profile in aging human monocytes to a more youthful profile. These results reveal the RXR pathway as a positive regulator of myelin debris clearance and a key player in the age-related decline in remyelination that may be targeted by available or newly-developed therapeutics.
2015-11-04 | GSE66988 | GEO
Project description:During demyelination myeloid cells remove myelin debris and promote remyelination. Dysfunctional myeloid cells are associated with peroxisomal leukodystrophies, yet the role of peroxisomes in myeloid cells responding to demyelination remains unknown. The impact of dysfunctional peroxisomes in demyelination-responding myeloid cells was interrogated in Abcd1 and Pex5 knockout mice using the cuprizone model for myelin damage. Abcd1 loss did not affect the demyelination response in myeloid cells, however, Pex5 deficiency impaired remyelination and significantly undermined myelin debris clearance. Molecular analysis in Pex5 depleted macrophages revealed repressed APOE activity and attenuated expression of the sterol exporter pathway integral to myelin debris metabolism, which was associated with an aggravated foamy macrophage phenotype in myelin engulfing myeloid cells. In summary, we report a critical contribution of peroxisomes to myelin debris clearance, myelin lipid processing, and pro-remyelinating properties in myeloid cells.
2025-11-13 | GSE272138 | GEO
Project description:Failure in remyelination is a key feature of progressive multiple sclerosis (MS) that drive neurodegeneration and accumulation of disabilities. Microglia crucially facilitate oligodendrocyte remyelination in MS lesions through myelin phagocytosis, and subsequent cholesterol metabolism and release. However, microglia lose this capacity in chronic demyelinated lesions, as they acquire a dysfunctional phenotype characterized by intracellular accumulation of lipid droplets due to impaired cholesterol processing of myelin debris. Given the abundance of microglia in chronic MS lesions, revitalizing their pro-remyelination capacity represents a critical repair strategy for progressive MS. Here, we reveal that dysregulation of neuregulin-1 underlies impaired remyelination in chronically demyelinated brain lesions. Therapeutic restoration of neuregulin-1 supports remarkable myelin regeneration by augmenting microglia capacity for clearance of myelin debris, cholesterol metabolism and efflux. Altogether, we demonstrate the promise of neuregulin-1 as an endogenous target to facilitate microglia reparative functions in progressive MS in which there is an unmet critical need for new treatments.
2026-03-09 | GSE282653 | GEO
Project description:Remyelination is a multistep regenerative process that results in the reformation of myelin sheaths around demyelinated axons and is a critical therapeutic target. Here we show that immediate access to a running wheel following toxin-induced demyelination in mice enhances oligodendrogenesis, myelin thickness, and the proportion of remyelinated axons. RNA-sequencing suggests broad activation of pro-remyelination pathways including phagocytosis by exercise and highlights peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1a) activation. Our study demonstrates that physical activity is an integrative means to enhance remyelination and details a multimodal mechanism including the pivotal PGC1a-dependent enhancement of myelin thickness.
2018-08-16 | GSE118592 | GEO
Project description:Vitamin D deficiency is a major environmental risk factor for the development of multiple sclerosis (MS). The major circulating metabolite of vitamin D (25OHD) is converted to the active form (calcitriol) by the hydroxylase enzyme CYP27B1. In MS lesions the tyrosine kinase MerTK expressed by microglia and macrophages regulates phagocytosis of myelin debris and apoptotic cells that can accumulate and inhibit tissue repair and remyelination. We show that calcitriol downregulates MerTK mRNA and protein expression in primary adult human microglia and monocyte-derived macrophages, thereby inhibiting myelin phagocytosis and apoptotic cell clearance. Proinflammatory myeloid cells express high levels of CYP27B1 compared to homeostatic (TGFb-treated) myeloid cells. Only proinflammatory cells in the presence of TNF-a generate calcitriol from 25OHD, resulting in repression of MerTK expression and function. The selective production of calcitriol in proinflammatory myeloid cells leading to downregulation of MerTK-mediated phagocytosis has the potential to reduce the risk for auto-antigen presentation while retaining the phagocytic ability of homeostatic myeloid cells, thereby contributing to inflammation reduction and enhanced tissue repair.
2020-04-21 | GSE148986 | GEO
Project description:There is little understanding of how aging serves as the strongest risk factor for several neurodegenerative diseases. Microglia, undergo age-related maladaptive changes, including increased inflammation, impaired debris clearance, and cellular senescence, yet specific mediators that regulate these processes remain unclear. The aged brain is rejuvenated by youth-associated plasma factors, including tissue inhibitor of metalloproteinases 2 (TIMP2), which we have shown acts on the extracellular matrix (ECM) to regulate synaptic plasticity. Given emerging roles for microglia in these processes, we examined the impact of TIMP2 on microglial function. We show that TIMP2 deletion in mice exacerbates microglial phenotypes associated with aging, including transcriptomic changes in cell activation, changes in lysosomal-associated markers and phagocytosis, and elevated levels of stress and inflammatory proteins in the brain extracellular space measured by in vivo microdialysis. Deleting specific cellular pools of TIMP2 in vivo increases microglial CD68 and alters myelin phagocytosis. Treating aged mice with TIMP2 reverses several phenotypes observed in our deletion models, resulting in decreased microglial activation, reduced proportions of proinflammatory microglia, and enhanced phagocytosis of physiological substrates. Our results identify TIMP2 as a modulator of age-associated microglia dysfunction. Harnessing its activity may mitigate detrimental effects of age-associated insults on microglia function.
2026-06-01 | GSE297916 | GEO
Project description:There is little understanding of how aging serves as the strongest risk factor for several neurodegenerative diseases. Microglia, undergo age-related maladaptive changes, including increased inflammation, impaired debris clearance, and cellular senescence, yet specific mediators that regulate these processes remain unclear. The aged brain is rejuvenated by youth-associated plasma factors, including tissue inhibitor of metalloproteinases 2 (TIMP2), which we have shown acts on the extracellular matrix (ECM) to regulate synaptic plasticity. Given emerging roles for microglia in these processes, we examined the impact of TIMP2 on microglial function. We show that TIMP2 deletion in mice exacerbates microglial phenotypes associated with aging, including transcriptomic changes in cell activation, changes in lysosomal-associated markers and phagocytosis, and elevated levels of stress and inflammatory proteins in the brain extracellular space measured by in vivo microdialysis. Deleting specific cellular pools of TIMP2 in vivo increases microglial CD68 and alters myelin phagocytosis. Treating aged mice with TIMP2 reverses several phenotypes observed in our deletion models, resulting in decreased microglial activation, reduced proportions of proinflammatory microglia, and enhanced phagocytosis of physiological substrates. Our results identify TIMP2 as a modulator of age-associated microglia dysfunction. Harnessing its activity may mitigate detrimental effects of age-associated insults on microglia function.
2026-06-01 | GSE297917 | GEO
Project description:Microglia are considered both pathogenic and protective during recovery from demyelination, but their precise role remains ill-defined. Here, using an inhibitor of colony stimulating factor 1 receptor (CSF1R), PLX5622, and mice infected with a neurotropic coronavirus (mouse hepatitis virus, strain JHMV), we show that depletion of microglia after clearance of virus infection resulted in impaired myelin repair and prolonged clinical disease. Microglia were required only during the early stages of remyelination. Notably, large deposits of extracellular vesiculated myelin and cellular debris were detected in the spinal cords of PLX5622-treated and not control mice, which correlated with decreased numbers of oligodendrocytes in demyelinating lesions in drug-treated mice. Further, gene expression analyses demonstrated differential expression of genes involved in myelin debris clearance, lipid and cholesterol recycling, and promotion of oligodendrocyte function. The results also demonstrate that microglial function could not be compensated by infiltrating macrophages. Together, these results demonstrate key roles for microglia in debris clearance and the initiation of remyelination following infection with a neurotropic coronavirus but are not necessary during later stages of remyelination.
2020-02-07 | GSE144911 | GEO
Project description:After stroke, microglia/blood-derived macrophages, together MF, clear dead cells and cellular debris in the infarcted brain through phagocytosis as an essential part of the repair/recovery process. However, the phagocytic capability of MF declines with age. Furthermore, aged MF become overactivated in response to stroke, enhancing secondary brain injury. Now, demonstrate that by reversing the age-related dysfunctions in MF through activating the retinoid x receptor (RXR), the recovery after stroke in the aged brain could be improved. Using RNA sequencing, we compared the transcriptomes between MF isolated from the brains of young and aged mice. We observed higher levels of pro-inflammatory genes and lower levels of phagocytosis-facilitating genes (Cd206, Cd36) expressed by aged MF. Meanwhile, the treatment with RXR agonist bexarotene (BEX) reversed the signature genes of microglia aging in the aged MF. With the in vivo phagocytosis model, we showed that BEX enhanced the phagocytic ability of aged MF. Using mouse MCAo stroke model, we established that BEX improved sensorimotor and cognitive recovery after MCAo in a myeloid-RXRa-specific and -dependent manner. In conclusion, we showed that activating RXRa partially restores age-related MF dysfunctions and that RXRa deficiency in MF limits the therapeutic effect of RXR in improving post-stroke recovery in the aged brain
2025-09-17 | GSE287142 | GEO