Increased expression of the β4 and α5 integrin subunits in cerebral blood vessels of transgenic mice chronically producing the pro-inflammatory cytokines IL-6 or IFN-α in the central nervous system

Evidence suggests that vascular function is strongly regulated by extracellular matrix (ECM) proteins via integrin-mediated signaling. To determine whether integrin expression on cerebral blood vessels is altered during chronic neuroinflammation, we examined β1 and β4 integrin expression in transgenic mice with astrocyte production of the pro-inflammatory cytokines interleukin-6 (IL-6) or interferon-α (IFN-α). Chronic production of IL-6 or IFN-α in the CNS promoted vascular expression of the β4 and α5 integrin subunits, and this was contributed mostly by astrocytes. Vascular expression of the ECM ligands laminin and fibronectin was also increased. Cell culture studies showed that astrocyte expression of the β4 and α5 integrins was significantly upregulated by IL-6 and IFN-α, respectively, while endothelial expression of these integrins was unchanged. These results show that astrocytes respond to IL-6 and IFN-α by upregulating integrin expression. We propose that during neuroinflammation, astrocytes attempt to increase adhesive interactions at the blood–brain barrier (BBB), in order to increase barrier integrity.