HUMAN NEUTROPHIL COLLAGENASE (MMP-8), IDENTIFIED IN BRONCHIECTASIS BAL FLUID, CORRELATES WITH SEVERITY OF DISEASE

Collagenases in bronchoalveolar lavage fluid (BALF) of patients with b ronchiectasis and healthy subjects were characterized using specific f unctional and immunologic assays. The BAL fluid contained interstitial collagenase and collagenolytic proteinases of bacterial origin. Colla genase activities, obtained after organomercurial activation, correlat ed with the severity of bronchiectasis. In severe cases, collagenase a ctivities were 3.5x10(-7) IU/L/48 h or 4.8x10(-6) IU/g/48 h (p<0.01), in moderate ones 1.74x10(-7) IU/L/48 h or 3.35x10(-6) IU/g/48 h (p<0.0 5), and in mild cases 0.32x10(-7) IU/L/48 h or 0.7x10(-6) IU/g/48 h (p <0.05). The corresponding activities in healthy control subjects were 0.08x10(-7) IU/L/48 h or 0.13x10(-6) IU/g/48 h. The cellular origin of interstitial collagenase was assessed with doxycycline inhibition tes t utilizing the differential sensitivity of fibroblast-type collagenas e/MMP-1 (IC50=280 mu M) and neutrophil-type collagenase/MMP-8 (IC50=26 mu M) to the anticollagenolytic, nonantimicrobial doxycycline action. Interstitial collagenase, contained in BALF, was totally inhibited by 100 mu M of doxycycline. It can therefore be concluded that most of m ammalian collagenase presented in inflamed fluid of bronchiectasis ori ginated from neutrophils. The molecular forms of neutrophil-type colla genase/MMP-8 were confirmed and analyzed by Western-blot, which showed evidence of the proteolytic conversion of the latent 85-kD MMP-8 proe nzyme species into active 65-kD molecular weight species. These findin gs strongly suggest involvement of proteolytic activation pathway of p roMMP-8, especially in severe and moderate forms of bronchiectasis. Fu rthermore, collagenolytic proteases of bacterial origins may also part icipate in tissue destruction of the lung.