Anti-inflammatory Effect of 9-cis Retinoic Acid on the Human Mast Cell Line, HMC-1

Mast cells play important roles in immune-related diseases, in particular, allergic diseases. Although 9-cis retinoic acid (9CRA) has been known as an immune regulator, its function in mast cells is not characterized well. In a previous paper, we demonstrated that 9CRA differentially decreases both CCR2 expression and the MCP-1-induced chemotactic activity of the human mast cell line, HMC-1 cells. In the present study, we examined the effects of 9CRA on the migration and expressions of inflammatory cytokines in HMC-1 cells. It was found that 9CRA significantly inhibited the migration of HMC-1 cells in response to stem cell factor (P<0.01), and it had no effect on the mRNA and protein expression of c-kit, a receptor binding to SCF. We further investigated the alternation of inflammatory cytokine expression and identified that 9CRA blocked the mRNA and protein expressions of Th2 cytokines such as interleukin (IL)-4 and IL-5. Taken together, our results demonstrate that 9CRA blocks SCF-induced cell movement and the protein secretion of IL-4 and IL-5, and this indicates that 9CRA may have anti-inflammatory effects on mast cells.