G protein-coupled receptor 84(GPR84) is a fatty acid receptor that is activated by mid-chain fatty acids (C9-C14). In human body, GPR84 is mainly expressed in bone marrow, followed by peripheral leukocytes and lung, and the expression level of GPR84 is low in physiological state. Inflammatory stimulation (such as lipopolysaccharide) can induce the high expression of GPR84 in monocytes/macrophages, suggesting that GPR84 is closely related to inflammation.