Nimesulide e Collagenasi: inibizione dell'attività enzimatica "in vitro"

Irreparable degradation of the extracellular matrix is a hallmark of severe inflammatory arthritis. In view of the central role that collagenase plays both in normal and pathological catabolism of the extracellular matrix, it is of interest to carry out detailed kinetic studies on this enzyme in order to check the effect showed by some NSAIDs like nimesulide, sodium meclophenamate and acetaminophen. The interaction between NSAIDs and collagenase 'in vitro' was studied by using a fluorogenic substrate MOCAc- Pro-Leu-Gly-Leu-A2pr(Dnp)-Ala-Arg-NH 2. After cleavage of the probe by collagenase the increased fluorescence, due to the removal of the NH 2- terminal dinitrophenyl group, was monitored and related to the enzyme activity. The presence of nimesulide induced a marked inhibition of the enzyme activity with an IC 50 of 1,90 μM and a K(i) of 0,83 μM. These concentrations was lower of the effective level of the drug found in the synovial fluid of patients receiving normal therapeutical dosage. Conversely, in the same experimental conditions, sodium meclophenamate gave lower inhibitory activity than nimesulide, showing an IC 50 = 26,80 μM and K(i) = 21,80 μM and acetaminophen did not affected the enzyme at all. These results support the hypothesis that nimesulide 'in vivo' may exert its antiinflammatory activity also via the inhibition of collagen degradation.