Lung Inflammation Resolution by RvD1 and RvD2 in a Receptor-Dependent Manner

Inflammation resolution is an active process via specialized pro-resolving mediators (SPMs) to fight invading microbes and repair tissue injury. RvD1 and RvD2 are SPMs produced from DHA during inflammation responses and show a benefit in treating inflammation disorders, but it is not completely understood how they act on vasculature and immune cells in the lung to promote inflammation resolution programs. Here, we studied how RvD1 and RvD2 regulated the interactions between endothelial cells and neutrophils in vitro and in vivo. In an acute lung inflammation (ALI) mouse model, we found that RvD1 and RvD2 resolved lung inflammation via their receptors (ALX/GPR32 or GPR18) and enhanced the macrophage phagocytosis of apoptotic neutrophils, which may be the molecular mechanism of lung inflammation resolution. Interestingly, we observed the higher potency of RvD1 over RvD2, which may be associated with unique downstream signaling pathways. Together, our studies suggest that the targeted delivery of these SPMs into inflammatory sites may be novel strategies with which to treat a wide range of inflammatory diseases.