The aim of the present study was to analyze the matrix metalloproteinase (MMP) activity during the evolution of interstitial renal fibrosis in a rat experimental model of unilateral ureteral obstruction. The interstitial type I collagenase and the gelatinolytic activities were analyzed by radiolabeled substrate degradation. Interstitial collagenase activity was low at all times while gelatinolytic activity increased on day 6 of evolution, with a decrease in activity from this point. The use of organomercurials revealed the presence of latent enzyme in all cases. Normal kidney samples contained MMP-9 in both active and proenzyme forms as revealed by zymography. On day 3 MMP-9 dimers appeared, and increased activity was observed until day 6. A decrease in the gelatinolytic activity was detected from days 9–15 of evolution. This observation was confirmed by Western blot analysis that revealed the presence of proMMP-9 mainly from days 6–12. Tissue inhibitor of metalloproteinase-1 (TIMP-1) was also detected alone and in combination with proMMP-1 and MMP-1, particularly from days 6–15 of evolution. The presence of MMP-9 and MMP-1 was detected in the cytoplasm of cortical tubular cells by immunohistochemistry, with no difference between the experimental and the normal kidneys. There was also an increase in collagen concentration from day 3 after surgery that increased during the entire evolution of the experimental model. This work reveals that the decrease in the MMP-9 and MMP-1 enzymatic activity, due to their interaction with TIMP-1 and to the lack of activation of the latent forms, may participate in the excessive collagen deposit during the evolution of experimental interstitial renal fibrosis.

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In this study we examined the production of gelatinases A and B (MMP-2 and MMP-9), and their natural inhibitors TIMP-1 and TIMP-2 in cell lines derived from different histologic types of lung cancer. Gelatinolytic activity was measured by zymography and radiolabeled gelatin degradation. Immunocytochemistry and Western blot analysis were performed to corroborate the presence of immunoreactive MMP-2, MMP-9, TIMP-1 and TIMP-2 proteins. The highest gelatinolytic activity was identified in the cell extracts from a small-cell carcinoma cell line. MMP-9 was observed in all samples as a proenzyme, while MMP-2 was present as zymogen in the squamous-cell and in the small-cell carcinomas, and in its active form in one squamous-cell carcinoma cell line. TIMPs were also present in the neoplastic lung cell lines. TIMP-1 was observed in the media of all cells as a 21-kD band, and as TIMP-1 polymers with the exception of the small-cell carcinoma samples. TIMP-2 was found as higher-order molecular immunoreactive complexes that may correspond to proMMP-2/TIMP-2 complexes. These results demonstrate that lung neoplastic cells produce both MMP-2 and MMP-9 and their inhibitors, with the small-cell carcinoma cell extracts showing the highest enzymatic activity. This gelatinolytic activity fits well with the clinical metastatic behavior of this type of lung cancer.

Purpose: To examine the in vitro effects of subretinal fluid (SRF) from patients with retinal detachment on extracellular matrix turnover. Methods: Matrix metalloproteinase (MMP) activity was explored by radiolabeled substrate degradation and zymography. Human lung fibroblasts were used to analyze SRF effects on collagen synthesis and cell proliferation. Transforming growth factor-β₂ (TGF-β₂) concentration was determined in SRF samples by a quantitative sandwich enzyme immunoassay. Results: MMP-2 and MMP-9 gelatinolytic activity was observed in all SRF samples. Collagenase activity was not detected in SRF from patients with holes and recurrent retinal detachment. All SRF samples stimulated fibroblast proliferation and collagen synthesis but SRF samples from recurrent retinal detachment patients with previous retinal tears had the largest effect with the largest TGF-β₂ concentration. Conclusions: The gelatinolytic activity found in all SRF samples might be associated with the retinal detachment process. Low collagenase activity with an increase in collagen synthesis could indicate a risk factor to the development of proliferative vitreoretinopathy.