AUTHOR=Carvalho-Paulo Dario , Bento Torres Neto João , Filho Carlos Santos , de Oliveira Thais Cristina Galdino , de Sousa Aline Andrade , dos Reis Renata Rodrigues , dos Santos Zaire Alves , de Lima Camila Mendes , de Oliveira Marcus Augusto , Said Nivin Mazen , Freitas Sinara Franco , Sosthenes Marcia Consentino Kronka , Gomes Giovanni Freitas , Henrique Ediely Pereira , Pereira Patrick Douglas Côrrea , de Siqueira Lucas Silva , de Melo Mauro André Damasceno , Guerreiro Diniz Cristovam , Magalhães Nara Gyzely de Morais , Diniz José Antonio Picanço , Vasconcelos Pedro Fernando da Costa , Diniz Daniel Guerreiro , Anthony Daniel Clive , Sherry David Francis , Brites Dora , Picanço Diniz Cristovam Wanderley TITLE=Microglial Morphology Across Distantly Related Species: Phylogenetic, Environmental and Age Influences on Microglia Reactivity and Surveillance States JOURNAL=Frontiers in Immunology VOLUME=12 YEAR=2021 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.683026 DOI=10.3389/fimmu.2021.683026 ISSN=1664-3224 ABSTRACT=

Microglial immunosurveillance of the brain parenchyma to detect local perturbations in homeostasis, in all species, results in the adoption of a spectrum of morphological changes that reflect functional adaptations. Here, we review the contribution of these changes in microglia morphology in distantly related species, in homeostatic and non-homeostatic conditions, with three principal goals (1): to review the phylogenetic influences on the morphological diversity of microglia during homeostasis (2); to explore the impact of homeostatic perturbations (Dengue virus challenge) in distantly related species (Mus musculus and Callithrix penicillata) as a proxy for the differential immune response in small and large brains; and (3) to examine the influences of environmental enrichment and aging on the plasticity of the microglial morphological response following an immunological challenge (neurotropic arbovirus infection). Our findings reveal that the differences in microglia morphology across distantly related species under homeostatic condition cannot be attributed to the phylogenetic origin of the species. However, large and small brains, under similar non-homeostatic conditions, display differential microglial morphological responses, and we argue that age and environment interact to affect the microglia morphology after an immunological challenge; in particular, mice living in an enriched environment exhibit a more efficient immune response to the virus resulting in earlier removal of the virus and earlier return to the homeostatic morphological phenotype of microglia than it is observed in sedentary mice.