Wang Yiyuan, Wan Xiaohong, Li Yusheng
Department of Emergency Medicine, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China.
Biotechnol Appl Biochem. 2025 Aug;72(4):883-896. doi: 10.1002/bab.2703. Epub 2024 Dec 2.
Dysfunction of the alveolar endothelial barrier plays a crucial role in the pathogenesis of septic acute lung injury (ALI). orexin B is a neuropeptide derived from orexin neurons in the lateral hypothalamus and has multiple biological functions. However, the physiological function of orexin B in sepsis is less reported. Here, we aimed to explore the protective effects of orexin B in sepsis-induced ALI and its underlying mechanisms. In this study, we established an ALI in vivo animal model in mice using cecal ligation and puncture (CLP) and an in vitro ALI model using mouse lung microvascular endothelial cells (MLMECs) induced with lipopolysaccharides (LPS). The animal experiments involved four groups: Sham, Sham+orexin B, CLP, CLP+orexin B. First, our results demonstrate that the levels of serum orexin B but not orexin A were reduced in septic mice. Correspondingly, the expression of orexin type 2 receptor (OX2R), but not orexin type 1 receptor (OX1R), was reduced in the lung tissue of septic mice. Administration of orexin B decreased the mortality in sepsis mice and improved M-CASS scores. Hematoxylin-eosin (H&E) staining assay demonstrated that administration of orexin B ameliorated histopathological lung injury. orexin B was also found to inhibit the inflammatory response in the lung tissues of septic mice by reducing the expression of tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and recombinant chemokine C-X-C-motif ligand 15 (CXCL15). Additionally, the total cell count and neutrophils in bronchoalveolar lavage fluid (BALF) were reduced by orexin B. Notably, orexin B alleviated vascular endothelial permeability in mice lung tissue by increasing the expression of the tight junction protein zonula occludens-1 (ZO-1) and occludin. In vitro experiments demonstrated that orexin B prevented LPS-induced endothelial permeability in mouse lung microvascular endothelial cells (MLMECs) by upregulating the expression of ZO-1 and occludin. These effects are mediated by rho-associated coiled-coil containing protein kinase 2 (ROCK2). Based on these findings, we conclude that orexin B alleviates sepsis-induced ALI by ameliorating endothelial permeability of lung microvascular endothelial cells.
肺泡内皮屏障功能障碍在脓毒症急性肺损伤（ALI）的发病机制中起关键作用。食欲素B是一种源自下丘脑外侧食欲素神经元的神经肽，具有多种生物学功能。然而，食欲素B在脓毒症中的生理功能报道较少。在此，我们旨在探讨食欲素B在脓毒症诱导的ALI中的保护作用及其潜在机制。在本研究中，我们使用盲肠结扎和穿刺（CLP）建立了小鼠体内ALI动物模型，并使用脂多糖（LPS）诱导的小鼠肺微血管内皮细胞（MLMECs）建立了体外ALI模型。动物实验分为四组：假手术组、假手术+食欲素B组、CLP组、CLP+食欲素B组。首先，我们的结果表明，脓毒症小鼠血清中食欲素B的水平降低，而食欲素A的水平未降低。相应地，脓毒症小鼠肺组织中食欲素2型受体（OX2R）的表达降低，而食欲素1型受体（OX1R）的表达未降低。给予食欲素B可降低脓毒症小鼠的死亡率并改善M-CASS评分。苏木精-伊红（H&E）染色分析表明，给予食欲素B可改善肺组织病理学损伤。还发现食欲素B通过降低肿瘤坏死因子α（TNF-α）、白细胞介素6（IL-6）和重组趋化因子C-X-C基序配体15（CXCL15）的表达来抑制脓毒症小鼠肺组织中的炎症反应。此外，食欲素B可降低支气管肺泡灌洗液（BALF）中的总细胞数和中性粒细胞数。值得注意的是，食欲素B通过增加紧密连接蛋白闭合蛋白-1（ZO-1）和闭合蛋白的表达来减轻小鼠肺组织中的血管内皮通透性。体外实验表明，食欲素B通过上调ZO-1和闭合蛋白的表达来防止LPS诱导的小鼠肺微血管内皮细胞（MLMECs）的内皮通透性。这些作用由含rho相关卷曲螺旋的蛋白激酶2（ROCK2）介导。基于这些发现，我们得出结论，食欲素B通过改善肺微血管内皮细胞的内皮通透性来减轻脓毒症诱导的ALI。
