Inhibition of the α7 nicotinic acetylcholine receptor alleviates pyroptosis in blood-brain barrier induced by Cryptococcusneoformans.

Abstract

Cryptococcus neoformans meningitis (CM), a severe AIDS-defining illness with high mortality, remains refractory to effective therapies. This study investigated the mechanisms underlying Cryptococcus neoformans (Cn)-induced disruption of the blood-brain barrier (BBB). Using in vitro models of cerebral microvascular endothelial cells, we demonstrated that Cn disrupted the BBB via adhesion and invasion, leading to pyroptosis in these cells. Furthermore, our findings revealed that Cn induced upregulation of the α7 nicotinic acetylcholine receptor (α7nAChR). Importantly, inhibition of α7nAChR alleviated pyroptosis caused by Cn. Interestingly, the CHRFAM7A gene product, a duplicated α7nAChR subunit, negatively regulated its activity, thereby mitigating Cn-induced pyroptosis in cerebral microvascular endothelial cells. Fungal ergosterol, a key virulence factor, plays a critical role in this process. It slowed the wound healing in cell scratch assays and induced pyroptosis in cerebral microvascular endothelial cells. Consistent with in vitro findings, in vivo experiments using immunosuppressed mouse models demonstrated that Cn increased BBB permeability, as evidenced by enhanced Evans blue leakage and reduced ZO-1 expression in the cerebral cortex. Additionally, Cn reduced vascular activity and regulated pyroptosis-related proteins in the mouse cerebral cortex. Notably, both pharmacological inhibition of α7nAChR with MLA and its genetic modulation via CHRFAM7A overexpression conferred significant survival benefits and alleviated Cn-induced pathological damage in mice. These findings provide novel insights and potential therapeutic targets for the prevention and treatment of CM.