MMP9 and stroke disorder: Some evidence indicates that changes in astrocytic proteins involved in BBB maintenance like metalloproteinase-2 and the toll-like receptor 4/metalloproteinase-9 (TLR4/MMP9) signaling pathway are upregulated after stroke, contributing to the disruption of astrocyte-endothelial junctions, consequently altering BBB permeability (Liu et al., 2017; Rosciszewski et al., 2018).