Silencing HMGB1 secretion inhibited EV71-induced blood-brain barrier dysfunction and neural inflammation by depressing astrocyte activation via sHh signal blockage.

It is unclear whether high mobility group protein B1 (HMGB1) is associated with the malignant characterization of hand, foot, and mouth disease (HFMD), and whether it plays a key regulatory role in the process of enterovirus 71 (EV71)-induced brain damage. Firstly, we analyzed the correlation between clinical information and HMGB1 concentrations in patients with mild and severe HFMD. Immunofluorescence was used to determine the expression level of HMGB1 in astrocytes. The levels of cellular inflammatory factors (IL-1β, IL-4, IL-6, TNF-α and TGF-β1), chemokines (CCL2, CXCL10 and CXCL12) and adhesion factors (integrin β, P-gp, VCAM-1 and ICAM-1) were detected by ELISA kits. Western blot was used to measure the levels of blood-brain barrier (BBB) stability related factors (retinoic acid (RA), ANG1, ApoE and IGF-1) in astrocytes and BBB structure related proteins (occluding, claudin, PTCH-1 and ZO-1) in endothelial cells. Clinical studies found that the expression of HMGB1 was closely related to the HFMD severity. Knockdown of HMGB1 alleviated EV71-induced neuron damage and inhibited cellular inflammation and apoptosis. Importantly, silencing HMGB1 depressed excessive proliferation and the inflammation response of astrocytes caused by EV71 infection. Furthermore, knockdown of HMGB1 enhanced BBB stability by improving astrocyte adhesion and endothelial tight junctions. Mechanistically, HMGB1 regulated the stability of BBB by regulating sHh signaling and secretion in astrocytes. In conclusion, the level of HMGB1 is closely related to the clinical symptoms of patients with HFMD, and inhibiting the expression of HMGB1 promotes BBB stability by promoting sHh signaling in astrocytes.