Impact of IL -9 and IL-33 in mast cells.

Cytokines serve as chemical communicators from one cell to another and most of them have pro-inflammatory activity. Mast cells have been recognised as important mediators of the pathogenesis of allergy and inflammation, suggesting a role for IL-33-mediated mast cell activation. IL-33 was recently identified as a ligand for the orphan IL-1 family receptor T1/ST2 and is mainly expressed by mast cells, fibroblasts, epithelial cells, and endothelial cells, particularly in high endothelial venules. IL-33 is a potent inducer of pro-inflammatory cytokines such as IL-1, IL-6, IL-13 and TNF, and chemokines (MCP-1), by mast cells. Substance P is capable to induce VEGF from mast cells, and IL-33, the newest pro-inflammatory member of the IL-1 cytokine family, augments the effect of SP in VEGF transcription and translation protein. IL-9 is a pleiotropic and is expressed by multiple T helper (TH) cell subsets. IL-9 promotes the expression of mast cell pro-inflammatory cytokines in vitro and is involved in Th2 responses. This article focuses on recent developments of mast cells, IL-9 and IL-33, and recent literature and investigations were reviewed.