A novel role of endocan in alleviating LPS-induced acute lung injury

Endotoxin induced acute lung injury (ALI) is a critical complication of some clinical illnesses. Endothelial cell dysfunction and excessive pro-inflammation cytokine release are pivotal to the injury of alveolar-capillary membrane which is the typical characteristic of endotoxic lung injury. As a potential marker of endothelial cells, endocan plays an important role in many endothelial-dependent pathophysiological diseases. We speculated that endocan have anti-inflammatory property in ALI. Here, we investigated the role of endocan in LPS-induced ALI. Mice were randomly divided into 4 groups. LPS were used to construct ALI mice model by aerosolization for 20 min. Endocan was intraperitoneal injected at 30 min before LPS exposure. Levels of TNF-α, IFN-γ, IL-1β, IL-6 and MPO activities were detected by indicated ELISA. Cell apoptotic rate was determined by Annexin V/PI kit, ROS level and MPTP were detected by DCFH-DA and JC-1 kit, respectively. Seahorse XF96 was applied to evaluate the alteration of OCR and ECAR. Western blot and qRT-PCR were used to detect indicated molecules. Endocan effectively decreased TNF-α, IFN-γ, IL-1β, and IL-6 levels as well as relieved pulmonary epithelium cell apoptosis caused by LPS exposure. Endocan significantly reversed LPS induced UPRmt and promoted cell metabolism reprogramming which were crucial for the protective characteristic of endocan in ALI mice model. The above findings suggested endocan could significantly suppress inflammatory response in ALI model through attenuating UPRmt associated apoptosis and switch cellular bioenergetics, indicating endocan could be considered as a promising compound against LPS induced ALI.