• Wen Tan, Lin Chen, Ya-Xin Wang, Li-Sha Hu, Wei Xiong, You Shang, and Shang-Long Yao.
• Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology; Department of Critical Care Medicine, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022; Department of Cardiac Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
• Chin. Med. J. 2018 May 20; 131 (10): 1167-1173.

BackgroundAcute lung injury (ALI) is a severe disease with high mortality and poor prognosis. Protectin DX (PDX), a pro-resolving lipid mediator, exhibits protective effects in ALI. Our experiment aimed to explore the effects and related mechanisms of PDX in mice with ALI induced by lipopolysaccharide (LPS).MethodsBALB/c mice were randomly divided into five groups: sham, LPS, LPS plus 1 ng of PDX (LPS + PDX-1 ng), LPS plus 10 ng of PDX (LPS + PDX-10 ng), and LPS plus 100 ng of PDX (LPS + PDX-100 ng). Bronchoalveolar lavage fluids (BALFs) were collected after 24 h, and total cells, polymorphonuclear leukocytes, monocyte-macrophages, and lymphocytes in BALF were enumerated. The concentration of interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor-alpha (TNF-α), macrophage inflammatory protein (MIP)-1α, and MIP-2 in BALF was determined, and histopathological changes of the lung were observed. The concentration of protein in BALF and lung wet/dry weight ratios were detected to evaluate pulmonary edema. After determining the optimal dose of PDX, neutrophil-platelet interactions in whole blood were evaluated by flow cytometry.ResultsThe highest dose of PDX (100 ng/mouse) failed to provide pulmonary protective effects, whereas lower doses of PDX (1 ng/mouse and 10 ng/mouse), especially 1 ng PDX, alleviated pulmonary histopathological changes, mitigated LPS-induced ALI and pulmonary edema, inhibited neutrophil infiltration, and reduced pro-inflammatory mediator (IL-1β, IL-6, TNF-α, and MIP-1α) levels. Meanwhile, 1 ng PDX exhibited pro-resolving functions in ALI including upregulation of monocyte-macrophage numbers and anti-inflammatory mediator IL-10 levels. The flow cytometry results showed that PDX could inhibit neutrophil-platelet interactions in ALI.ConclusionPDX exerts protective effects in LPS-induced ALI by mitigating pulmonary inflammation and abrogating neutrophil-platelet interactions.

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