The Regulation of the CNS Innate Immune Response Is Vital for the Restoration of Tissue Homeostasis (Repair) after Acute Brain Injury: A Brief Review

Figure 4

The figure shows the interactions between stem cells expressing the CXCR4 receptor and stroma-derived factor SDF-1 with the complement anaphylotoxin chemoattractants C3a and C5a; tissue damage contains the chemoattractant Hypoxia factor (HF-1), thrombin and complement anaphylotoxins (C3a and C5a). Stem cells express the (NIReg) immunoregulatory signal CD200 that inhibits microglial activation via the counter receptor CD200R. T cells are also inhibited through several different inhibitory pathways expressed by stem cells as well as stimulating Tregs; these interactions all reduce the severity of the inflammation and stimulate stem cell migration into areas of inflammation to assist with tissue repair; these effects are termed “therapeutic plasticity”.