LPA2 Alleviates Septic Acute Lung Injury via Protective Endothelial Barrier Function Through Activation of PLC-PKC-FAK

Abstract

Ruifeng Bai,1 Jianqiu Pei,1 Shengqiang Pei,1 Xiangfeng Cong,1 Jerold Chun,2 Fang Wang,1,3,4 Xi Chen1,3 1State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China; 2Neuroscience Drug Discovery, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA; 3Diagnostic Laboratory Service, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China; 4Department of Clinical Laboratory, Fuwai Yunnan Cardiovascular Hospital, Kunming, People’s Republic of ChinaCorrespondence: Xi Chen; Fang Wang, Email [email protected]; [email protected]: Increased endothelial permeability of pulmonary vessels is a primary pathological characteristic of septic acute lung injury (ALI). Previously, elevated lysophosphatidic acid (LPA) levels and LPA2 (an LPA receptor) expression have been found in the peripheral blood and lungs of septic mice, respectively. However, the specific role of LPA2 in septic ALI remains unclear.Methods: A lipopolysaccharide (LPS)-induced model of sepsis was established in wild-type (WT) and global LPA2 knockout (Lpar2−/−) mice. We examined mortality, lung injury, assessed endothelial permeability through Evans blue dye (EBD) assay in vivo, and transendothelial electrical resistance (TEER) of mouse lung microvascular endothelial cells (MLMECs) in vitro. Enzyme-linked immunosorbent assay (ELISA), histopathological, immunofluorescence, immunohistochemistry, and Western blot were employed to investigate the role of LPA2 in septic ALI.Results: Lpar2 deficiency increased vascular endothelial permeability, impaired lung injury, and increased mortality. Histological examination revealed aggravated inflammation, edema, hemorrhage and alveolar septal thickening in the lungs of septic Lpar2−/− mice. In vitro, loss of Lpar2 resulted in increased permeability of MLMECs. Pharmacological activation of LPA2 by the agonist DBIBB led to significantly reduced inflammation, edema and hemorrhage, as well as increased expression of the vascular endothelial tight junction (TJ) protein zonula occludens-1 (ZO-1) and claudin-5, as well as the adheren junction (AJ) protein VE-cadherin. Moreover, DBIBB treatment was found to alleviate mortality by protecting against vascular endothelial permeability. Mechanistically, we demonstrated that vascular endothelial permeability was alleviated through LPA-LPA2 signaling via the PLC-PKC-FAK pathway.Conclusion: These data provide a novel mechanism of endothelial barrier protection via PLC-PKC-FAK pathway and suggest that LPA2 may contribute to the therapeutic effects of septic ALI.Keywords: septic ALI, LPA, vascular endothelial permeability, LPA2, lung microvascular endothelial cells

Keywords

• septic ali
• lpa
• vascular endothelial permeability
• lpa2
• lung microvascular endothelial cells