β-Dystroglycan Downregulation and Astrocytic Alterations: A Possible Role in Blood-Brain Barrier Disruption During...

Blood-brain barrier (BBB) breakdown is a critical step in the pathogenesis of cerebral malaria, leading to edema. However, the mechanisms responsible for BBB disruption and edema development are unclear. Here, we report some key molecular players present at the gliovascular interface that alter BBB integrity, focusing on early astrocyte changes in disease progression to the terminal stage. By using an experimental cerebral malaria (ECM) model, the changes at two pathological stages of disease at 5 days post-infection (d.p.i) (early asymptomatic stage) and 7 days post-infection (terminal stage) were investigated. Early treatment with artemether (ARM) was conducted to monitor the recovery during pathology. Initially, brain water content and BBB integrity were measured. The protein expression patterns were assessed by immunoblotting, and their localisations were visualized by immunohistochemical staining. The association between various proteins was determined via immunofluorescence staining analysis. We found increased Evans blue dye extravasation, FITC-dextran leakage, and brain edema at the terminal stage of the disease compared with the ARM-treated group. The altered expression levels of various molecules present at the gliovascular unit were observed even from the early stage of the disease. Furthermore, immunohistochemical analysis revealed loss of β-dystroglycan (β-DG), altered astrocyte morphology, and reduced tight junction protein zonula occludens-1 (ZO-1) and collagen IV expression during disease. In summary, these results suggested that β-DG cleavage by matrix metalloproteinase-9 (MMP-9) results in the disruption of astrocytic cellular connection with vasculature, and when dystrophin-glycoprotein complex (DGC) proteins are dysregulated, it leads to the development of edema.