Astragalus membranaceus-derived exosomes alleviate traumatic brain injury by inhibiting SERPINE1/HIF-1α/NLRP3-mediated pyroptosis.

OBJECTIVE: Pyroptosis is recognized as a critical contributor to the secondary injury following traumatic brain injury (TBI), and its inhibition has been shown to preserve neuronal integrity and improve neurological outcomes. This study aimed to investigate the therapeutic effects of Astragalus membranaceus (AM)-derived exosomes on TBI-induced pyroptosis and elucidate the underlying mechanism. METHODS: AM-derived exosomes were purified via sucrose density gradient ultracentrifugation and subsequently characterized. The effects of AM-derived exosomes in TBI were assessed in HT22 neuronal cells subjected to scratch injury and in a controlled cortical impact (CCI) mouse model of TBI. Neurological outcomes were evaluated through histopathological staining, neurologic severity scoring, grip strength testing and neurological function evaluation. Pyroptosis was detected using flow cytometry following caspase-1 and propidium iodide staining. NLRP3 activator BMS-986299 was used to determine whether activation of NLRP3 could reverse the inhibitory effects of AM-derived exosomes on pyroptosis. RESULTS: AM-derived exosomes significantly enhanced cell viability and reduced neuronal pyroptosis and pyroptotic markers (cleaved caspase-1, GSDMD-N, IL-1β and IL-18), alongside downregulating SERPINE1, HIF-1α, and NLRP3 expression. Activation of NLRP3 by BMS-986299 partially abolished the anti-pyroptotic effects mediated by AM-derived exosomes. In vivo, systemic administration of AM-derived exosomes ameliorated neurological deficits, improved motor function, attenuated hippocampal neuronal loss, and suppressed SERPINE1/HIF-1α/NLRP3 signaling. AM-derived exosomes showed excellent biocompatibility and the ability to penetrate the blood-brain barrier. CONCLUSION: These findings demonstrate that AM-derived exosomes represent a promising therapeutic approach for TBI by suppressing pyroptosis and facilitating functional recovery through inhibition of the SERPINE1/HIF-1α/NLRP3 axis.