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- Han, JM, et al.
(author)
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Sex-Specific Effects of Microglia-Like Cell Engraftment during Experimental Autoimmune Encephalomyelitis
- 2020
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In: International journal of molecular sciences. - : MDPI AG. - 1422-0067. ; 21:18
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Journal article (peer-reviewed)abstract
- Multiple sclerosis (MS) is a chronic neuroinflammatory disorder of the central nervous system (CNS) that usually presents in young adults and predominantly in females. Microglia, a major resident immune cell in the CNS, are critical players in both CNS homeostasis and disease. We have previously demonstrated that microglia can be efficiently depleted by the administration of tamoxifen in Cx3cr1CreER/+Rosa26DTA/+ mice, with ensuing repopulation deriving from both the proliferation of residual CNS resident microglia and the engraftment of peripheral monocyte-derived microglia-like cells. In this study, tamoxifen was administered to Cx3cr1CreER/+Rosa26DTA/+ and Cx3cr1CreER/+ female and male mice. Experimental autoimmune encephalomyelitis (EAE), a widely used animal model of MS, was induced by active immunization with myelin oligodendrocyte glycoprotein (MOG) one month after tamoxifen injections in Cx3cr1CreER/+Rosa26DTA/+ mice and Cx3cr1CreER/+ mice, a time point when the CNS niche was colonized by microglia derived from both CNS microglia and peripherally-derived macrophages. We demonstrate that engraftment of microglia-like cells following microglial depletion exacerbated EAE in Cx3cr1CreER/+Rosa26DTA/+ female mice as assessed by clinical symptoms and the expression of CNS inflammatory factors, but these findings were not evident in male mice. Higher major histocompatibility complex class II expression and cytokine production in the female CNS contributed to the sex-dependent EAE severity in mice following engraftment of microglia-like cells. An underestimated yet marked sex-dependent microglial activation pattern may exist in the injured CNS during EAE.
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- Han, JM, et al.
(author)
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Underestimated Peripheral Effects Following Pharmacological and Conditional Genetic Microglial Depletion
- 2020
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In: International journal of molecular sciences. - : MDPI AG. - 1422-0067. ; 21:22
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Journal article (peer-reviewed)abstract
- Microglia, predominant parenchymal resident macrophages in the central nervous system (CNS), are crucial players in neurodevelopment and CNS homeostasis. In disease conditions, pro-inflammatory microglia predominate over their regulatory counterparts, and are thus a potential immunotherapeutic target. It has been well documented that microglia can be effectively depleted using both conditional genetic Cx3cr1Cre-diphtheria toxin receptor (DTR)/diphtheria toxin subunit A (DTA) animal models and pharmacological colony-stimulating factor 1 receptor (CSF1R) inhibitors. Recent advances using these approaches have expanded our knowledge of the multitude of tasks conducted by microglia in both homeostasis and diseases. Importantly, experimental microglial depletion has been proven to exert neuroprotective effects in an increasing number of disease models, mostly explained by reduced neuroinflammation. However, the comprehensive effects of additional targets such as circulating monocytes and peripheral tissue macrophages during microglial depletion periods have not been investigated widely, and for those studies addressing the issue the conclusions are mixed. In this study, we demonstrate that experimental microglial depletion using both Cx3cr1CreER/+Rosa26DTA/+ mice and different doses of CSF1R inhibitor PLX3397 exert crucial influences on circulating monocytes and peripheral tissue macrophages. Our results suggest that effects on peripheral immunity should be considered both in interpretation of microglial depletion studies, and especially in the potential translation of microglial depletion and replacement therapies.
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