Mast cell neutral proteases

Mast cell neutral proteases have also been implicated in tissue remodelling. Canine tryptase induces proliferation of Chinese hamster and rat fibroblasts and also proten-tiates their respronse to basic FGF (Ruoss et al., 1991). 

Kaartinen M, Penttila A, Kovanen PT Accumulation of activated mast cells in the shoulder region of human coronary atheroma, the predilection site of atheromatous rupture. Circulation 1994 90 1669. Kaartinen M, Penttila A. Kovanen PT Mast cells of two types differing in neutral protease composition in the human aortic intima. Demonstration of tryptase- and tryptase/chymase-containing mast cells in normal intimas, fatty streaks, and the shoulder region of atheromas. Arterioscler Thromb 1994 14 966. 

Neutral and acidic serine proteases released from mast cells-tryptase MCX may damage type IV collagen and the intercellular matrix. Eosinophil chemotactic factors... 

Once sensitivity has been established, that is, once hapten-specific IgE-producing B cells have been formed, exposure to even small amounts of hapten can induce a cascade of events that lead to immediate reactions, such as anaphylaxis (210). Briefly, preformed IgE antibodies to drug determinants recognize the hapten-carrier complex and fix to the surface of mast cells or basophils, triggering the release of a series of mediators, such as histamine, neutral proteases, biologically active arachidonic acid products, and cytokines. This ultimately leads to a clinical spectrum that ranges from a mUd local reaction to anaphylactic shock. 

Irani, A.A., Schechter, N.M., Craig, S.S., DeBlois, G. and Schwartz, L.B. (1986). Two types of human mast cells that have distinct neutral protease compositions. Proc. Natl. Acad. Sci. USA 83, 4464-4468. 

The action of VIP at its receptor is competitive with its degradation by proteases found in the microenvironment of the receptor. VIP is known to be a favored substrate for NEP, mast cell tryptase and mast cell chymase, all of which are active at the neutral pH likely to prevail in the extracellular microenvironment. Recombinant human... 

Mast cells, positioned in the asthmatic airways, also play a major role in the maintenance of the condition. During the active disease, these cells are primed to secrete preformed and newly generated inflammatory mediators, neutral proteases, cysteinyl leukotrienes, cytokines, and chemokines [73]. The local delivery of glucocorticoids to the affected tissues has been found to reduce significantly the number of mast cells present. In one study in which glucocorticoids were directly applied to mouse dermis, the number of mast cells decreased. No direct effect of the glucocorticoids on the mast cells themselves was observed thus, the decrease was probably the result of increased apoptosis [74]. 

Irani AA, Schwartz LB. Neutral proteases as indicators of human mast cell heterogeneity. In Schwartz LB, ed. Neutral Proteases of Mast Cells. Basel Karger, 1990 146. 

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