Are proteases used as anti-inflammatory agents in reality accelerating the inflammatory process?

A possible anti-inflammatory effect of intraduodenally administered trypsin was investigated using the paw oedema and pleurisy models of carrageenan-induced inflammation in rats. No anti-inflammatory effect was detected by plethysmography or on the basis of pleural leukocyte migration in treated animals compared to a sham group. The groups were implanted with an intraduodenal catheter after treatment with metopyrone, an inhibitor of endogenous corticosteroid synthesis. Since surgical stress induces an anti-inflammatory effect of its own; the sham group was an important control. Metopyrone antagonized surgical stress, and trypsin inhibited oedema by about 16% four hours after carrageenan administration, a nonsignificant reduction. Evans blue dye protein leakage into the peritoneal cavity as a measure of vascular permeability demonstrated a pro-inflammatory effect of trypsin. The present results lead us to propose that trypsin may be acting not as anti-inflammatory agent but by accelerating the inflammatory process, thereby reducing the duration of the process.