Ligation of selectin L and integrin CD11b/ CD18 provides stimulatory signals to neutrophils which induce secretion of gelatinase B that may facilitate their transmigration into sites of inflammation.
To examine the clinical significance of neutrophil gelatinase in rheumatic diseases, plasma and synovial fluid (SF) gelatinase levels were determined in 62 patients with rheumatoid arthritis (RA), 12 patients with ankylosing spondylitis (AS), 18 patients with osteoarthritis (OA) and 17 healthy controls. The gelatinase level was measured by enzyme-linked immunoassay (ELISA). The assay had a sensitivity of 1 ng/ml and a working range of 5-25 ng/ml. Gelatinase levels were significantly higher in the plasma of patients with RA and of patients with RA complicated by amyloidosis or vasculitis as compared to those of healthy controls. Moreover, the mean value of gelatinase in the plasma of patients with RA complicated by vasculitis was found to be significantly higher than that of RA patients without vasculitis. A significant increase in gelatinase concentration was also observed in the plasma of AS patients but not in the plasma of patients with OA. The concentration of gelatinase in the RA SF samples was much higher (18-fold) than the level of the enzyme in the plasma of RA patients. There was also a higher concentration of gelatinase (four-fold) in OA SF compared with OA plasma. The results suggested that circulating gelatinase may reflect some degree of neutrophil activation in patients with inflammatory arthritis, especially in those with RA complicated by vasculitis. However, the results did not allow a differentiation between chronic and acute inflammation.
The effect of collagen degradation products by bacterial (BCDP) and synovial fluid collagenase (SCDP) on histamine release from peritoneal mast cells of rat was estimated. Some BCDP as well as SCDP released 60-80% of mast cell histamine. In BCDP fraction the most active were BCDP II (m.wt. 13 kD) and BCDP III (m.wt. 6 kD). The last contained the highest percentage of hydroxyproline. As compared with bradykinin, BCDP III was about 50 fold more active as histamine releaser.
During the course of carrageenan-induced inflammation in rats major changes were observed in the activities of neutrophil granule enzymes. The activities of three enzymes--gelatinase, collagenase and beta-glucuronidase, the markers of three different types of granules, have been measured and compared to those of a control group of animals. Total collagenase and gelatinase activities of control rats were 59.4 +/- 3.6 (mean +/- SD) and 23.0 +/- 2.9 units/mg protein, respectively. Significantly reduced levels of both collagenase (35.6 +/- 2.5 units) (p less than 0.05) and gelatinase (7.1 +/- 0.7 units) (p less than 0.001) were measured in the blood neutrophils of inflamed rats; and the collagenase activity of neutrophils derived from inflamed pleural exudate was also significantly decreased to a level of 19.7 +/- 1.8 units/mg protein (p less than 0.01). However, the gelatinase activity of exudate neutrophils did not differ from that of blood cells of inflamed rats. In contrast, no change was found for the beta-glucuronidase activity in blood neutrophils of control and inflamed rats. These observations support the concept that during the inflammatory response in rats, neutrophils in the circulation may become activated as judged by the extracellular secretion of collagenase and gelatinase. Therefore, neutrophils accumulating in acute inflammatory lesions contain decreased levels of collagenolytic enzymes and the significance of this observation is discussed.
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