Resolution of inflammation and repair after ischemic brain injury

Abstract

After ischemic stroke, proinflammatory molecules known as danger-associated molecular patterns (DAMPs) originating from damaged brain cells recruit and activate immune cells (neutrophils, macrophages, lymphocytes) further eliciting innate and adaptive immunity. During the acute phase from day 1 to day 3 of the stroke onset, macrophages play a major role in the progression of inflammation, promoting the destruction of brain tissue. During the recovery phase, from day 3~4 to day 7 after stroke onset, infiltrating macrophages switch to repairing macrophages, which clear the DAMPs and promote tissue repair by producing neurotrophic factors. Adaptive immunity during the late or chronic phase (> day 7) of stroke has not been well investigated. Recent studies have also indicated that antigen-specific T cells, especially regulatory T cells (Tregs), play major roles in neural repair. This review focuses mainly on the resolution of inflammation and tissue repair by macrophages and Tregs.