RvD1 ameliorates LPS-induced acute lung injury via the suppression of neutrophil infiltration by reducing CXCL2 expression and release from resident alveolar macrophages

Acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS) are life-threatening critical syndromes characterized by the infiltration of a large number of inflammatory cells that lead to an excessive inflammatory response. Resolvin D1 (RvD1), an endogenous lipid mediator, is believed to have anti-inflammatory and proresolving effects. In the present study, we examined the impact of RvD1 on the pulmonary inflammatory response, neutrophil influx, and lung damage in a murine model of lipopolysaccharide (LPS)-induced ALI. Treatment with RvD1 protected mice against LPS-induced ALI, and compared to untreated mice, RvD1-treated mice exhibited significantly ameliorated lung pathological changes, decreased tumor necrosis factor-alpha (TNF-alpha) concentrations and attenuated neutrophil infiltration. In addition, treatment with RvD1 attenuated LPS-induced neutrophil infiltration via the downregulation of CXCL2 expression on resident alveolar macrophages. Finally, BOC-2, which inhibits the RvD1 receptor lipoxin A4 receptor/formyl peptide receptor 2 (ALX/FPR2), reversed the protective effects of RvD1. These data demonstrate that RvD1 ameliorates LPS-induced ALI via the suppression of neutrophil infiltration by an ALX/FPR2-dependent reduction in CXCL2 expression on resident alveolar macrophages.