Matrix metalloproteinases 2 and 9 in indomethacin-induced rat gastric ulcer

The restoration of functional connective tissue is a major goal of the wound healing process. The 72- and 92-kD gelatinases (MMP-2 and MMP-9) are extracellular matrix metalloproteinases (MMPs), which are known to degrade type IV and V collagens and gelatin, and have a potential role in wound healing. The spatial and temporal gelatinolytic activities of MMP-2 and MMP-9 were analyzed as a function of ulcer age, in homogenates of rat, indomethacin-induced, chronic gastric ulcers. The rats were sacrificed on 1, 3, 7, 12, 18, 24 and 28 days after subcutaneous indomethacin injections. Zymographic analyses revealed elevated activation of MMP-9 and latent and active MMP-2 in gastric ulcers, when compared to gastric tissue from non-indomethacin-treated rats. The intact tissue and tissue from ulcerous lesions contained MMP-2. The highest activity of MMP-2 was found in 3 day gastric ulcers and returned to the control level by day 24. MMP-9 was not present in the intact tissue and the highest gelatinolytic activity of MMP-9 was also observed on the 3rd day after administration of indomethacin. The activity thereafter decreased and returned to the control level by day 24. In situ hybridization was used to evaluate which cells synthesize MMP-2 and MMP-9. MMP-2 was seen mostly in fibroblast-like cells in the submucosa and MMP-9 in macrophage-like cells in the mucosa on the margins of the ulcers. Thus, we conclude that these two MMPs seem to have different functions during the gastric ulcer injury/healing process. MMP-2 may participate in the physiological turnover of the gastric extracellular matrix, whereas MMP-9 may be important in the early phase of gastric ulcer formation and also in the healing process.