CONSTITUTIVE EXPRESSION OF MOUSE MAST-CELL PROTEASE-1 IN NORMAL BALB C MICE AND ITS UP-REGULATION DURING INTESTINAL NEMATODE INFECTION/

Rodent intestinal mucosal mast cells (IMMC) store and secrete soluble granule serine proteases, the beta-chymases, which may promote epithel ial permeability during intestinal hypersensitivity reactions. The bet a-chymase mouse mast cell protease-1 (mMCP-1) is generally considered to be expressed late in the in vitro differentiation of mast cells. Th e purpose of this study was to determine the kinetics of mMCP-1 transc ription and expression in vivo during nematode-induced IMMC hyperplasi a. Concentrations of mMCP-1 in blood and jejunum of BALB/c mice were q uantified by enzyme-linked immunosorbent assay before and at various s tages after infection with the intestinal nematode Nippostrongylus bra siliensis. Mature mMCP-1 enzyme was detected in jejunal homogenate (19 4 ng/mg soluble protein) and in blood (8.3 ng/ml serum) from normal un infected BALB/c mice. Maximal IMMC hyperplasia occurred 7-14 days post infection and was significantly correlated with increased levels of m MCP-1 in jejunum (r = 0.58, P < 0.001) and with raised concentrations of mMCP-1 in serum (r = 0.66, P < 0.001). Transcription of the mMCP-1 gene was detected by RNA blotting in normal, uninfected jejunum, but t ranscription was up-regulated after infection with maximal transcripti on occurring on days 7 and 14. In conclusion, mMCP-1 transcription, st orage and secretion occur constitutively in normal BALB/c jejunum but this basal secretion is up-regulated during nematode infection, sugges ting both a physiological and pathological function for this protease.