Interleukin-1β stimulates collagenase production by cultured human periodontal ligament fibroblasts

To examine the effects of interleukin-lβ (IL-1β) on collagenase production by human periodontal ligament fibroblasts (PLF) and gingival fibroblasts (GF) in Culture, collagenase activity in conditioned media was determined using a novel procedure that circumvented interference by enzyme inhibitors. Fibroblasts obtained from five paired periodontal ligament and gingival tissues were cultured for two weeks, and then incubated for a further 72 h in α-MEM supplemented with various concentrations of IL-1β (0 to 1250 pg/ml). The conditioned media from individual cultures were harvested and treated with dithiothreitol to inactivate TIMPs, and then with APMA, to activate the latent collagenase. Collagenase activity was measured fluorometrically using FITC-collagen as a substrate. IL-lβ induced a ～2.4 to 5.2-fold increase in collagenase activity in PLF compared to a ～1.4 to 2.2-fold increase in GF. These results are in contrast to previous studies in which collagenase activity was measured in the presence of TIMPs, and indicate that PLF are more sensitive to IL-1β than GF. Since both PLF and GF are present in periodontal lesions, it is possible that collagenase secretion stimulated by exposure to inflammatory cell products such as IL-lβ may participate in the destruction of collagen fibers involved in periodontal attachment.