基于小胶质细胞OPN/CTSB/NLRP3轴介导的炎症反应探讨H2S促进缺氧缺血性脑损伤后神经功能重建的机制研究

神经炎症反应是缺氧缺血性脑损伤（HIBD）预后不良的重要原因。我们曾报道外源性H2S可改善HIBD新生鼠神经行为预后，但其机制不详。新近我们利用蛋白质组学分析发现，HIBD新生鼠受损皮层中骨桥蛋白（OPN）显著上调，溶酶体通路显著富集并涉及组织蛋白酶B（CTSB）；同时发现在HIBD中OPN特异性定位于激活的小胶质细胞溶酶体，H2S的抗炎作用与其下调OPN表达正相关。由此我们推测HIBD后OPN表达上调并募集于小胶质细胞溶酶体，诱导其功能紊乱促进CTSB释放至胞质，从而激活NLRP3炎症小体；H2S通过调控小胶质细胞OPN/CTSB/NLRP3轴介导的炎症反应，促进HIBD后神经功能重建。本课题拟通过小胶质细胞条件敲除OPN小鼠联合体外实验，揭示OPN对HIBD小胶质细胞溶酶体功能及炎症反应的影响，阐明外源性H2S改善HIBD后神经功能障碍的机制，为探讨HIBD治疗提供新的靶点和实验依据。

Neuroinflammatory response is a leading cause of poor prognosis after hypoxic-ischemic brain injury (HIBD). Our previous work has demonstrated that exogenous H2S improves the neurobehavioral deficits following HI insult in neonatal mice, but the exact mechanisms remain unknown. Recently, we found that the expression of osteopontin (OPN) was markedly up-regulated in the ipsilateral cortex following HIBD in neonatal mice with TMT-based proteomic analysis. KEGG enrichment analysis indicated that the different proteins in HIBD group were enriched in lysosome pathway, including cathepsin B (CTSB). Furthermore, OPN was only colocalized in activated microglial lysosome. Exogenous H2S treatment down-regulated the expression of OPN, concomitant with attenuating neuroinflammation following HIBD in neonatal mice. Arising from this, we hypothesized that OPN expression was upregulated and accumulated in the microglial lysosome, which caused lysosomal dysfunction, promoted the release of CTSB to cytoplasm and activated NLRP3 inflammasome following HIBD; Endogenous H2S regulated OPN/CTSB/NLRP3 axis to attenuate the neuroinflammatory response and improve neurological function remodeling following HIBD in neonatal mice. Using microglial conditional OPN deficient mice in HIBD in vivo and in vitro, we aim to investigate the role of OPN in the lysosomal function of microglia and neuroinflammatory response, to elucidate the novel mechanisms of exogenous H2S to improve neurological dysfunction following HIBD. This project will provide new therapeutic target and experimental basis in HIBD.