A novel function for transforming growth factor-β1:: Upregulation of the expression and the IgE-independent extracellular release of a mucosal mast cell granule-specific β-chymase, mouse mast cell protease-1

Intestinal mucosal mast cells (IMMC) express granule neutral proteases that are regulated by T-cell-derived cytokines, including interleukin-3 (IL-3) and IL-9, and by stem cell factor (SCF). The IMMC-specific chymase, mouse mast cell protease-1 (mMCP-1), is released in substantial quantities into the blood stream during gastrointestinal allergic responses. We used cultured bone marrow-derived mast cells (mBMMC) to identify cytokines that regulate the expression and extracellular release of mMCP-1, When grown in IL-3-rich WEHI (15% vol/vol) and 50 ng/mL recombinant rat SCF (rrSCF) bone marrow cells supplemented with IL-9 (5 ng/mL) differentiated into mBMMC that expressed a maximum of less than 250 ng mMCP-1/10(6) cells and 189 ng mMCP-1/mL of culture supernatant. Supplementation of the same three cytokines with transforming growth factor-beta(1) (TGF-beta(1); 1 ng/mL) resulted in substantially enhanced expression (6 mu g/10(6) mBMMC) and extracellular release (2 mu g/mL of culture supernatant) of mMCP-1. The response to TGF-beta(1) was dose-dependent, with maximal effect at 1 ng/mL, and was associated with immunohistochemical and ultrastructural changes in the secretory granules. IL-9-induced expression of mMCP-1 may be due to endogenously expressed TGF-beta(1), because it was blocked by anti-TGF-beta antibodies. In conclusion, the expression and extracellular release of the IMMC-specific chymase, mMCP-1, is strictly regulated by IGF-beta(1). (C) 1999 by The American Society of Hematology.