Dual microglia effects on blood brain barrier permeability induced by systemic inflammation.

Haruwaka, Koichiro; Ikegami, Ako; Tachibana, Yoshihisa; Ohno, Nobuhiko; Konishi, Hiroyuki; Hashimoto, Akari; Matsumoto, Mami; Kato, Daisuke et al. · Nat Commun · 2019

basic_science · Level V

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Abstract

Microglia survey brain parenchyma, responding to injury and infections. Microglia also respond to systemic disease, but the role of blood-brain barrier (BBB) integrity in this process remains unclear. Using simultaneous in vivo imaging, we demonstrated that systemic inflammation induces CCR5-dependent migration of brain resident microglia to the cerebral vasculature. Vessel-associated microglia initially maintain BBB integrity via expression of the tight-junction protein Claudin-5 and make physical contact with endothelial cells. During sustained inflammation, microglia phagocytose astrocytic end-feet and impair BBB function. Our results show microglia play a dual role in maintaining BBB integrity with implications for elucidating how systemic immune-activation impacts neural functions.

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