Effects of IL-17 on human gingival fibroblasts

Interleukin ( IL)-17 is present in inflammatory periodontal lesions, thus suggesting a role in mediating inflammation. We tested the hypothesis that IL-17, especially when combined with interferon ( IFN)-gamma, may modulate the responses of human gingival fibroblasts ( HGFs).IL- 17 induced IL-8 and minimal intercellular adhesion molecule ( ICAM)-1 expression. It had no effect on expression of HLA-DR, CD40, or the immune-suppressive enzyme indoleamine 2,3-dioxygenase (IDO). The effects of IL-17 on HGFs were compared with those of IFN-gamma. Unlike IL-17,IFN-gamma augmented the expression of HLA-DR, ICAM-1, and IDO, but not IL-8. Thus, IL-17 and IFN-gamma induce different HGF responses when administered separately. Interestingly, when IL-17 and IFN-gamma were combined, marked enhancement of ICAM-1, IL-8, and IDO expression by HGFs was observed. These findings suggest that IL-17, especially when combined with IFN-gamma, could play an important role in immune modulation through stimulation of HGFs in periodontal disease. Abbreviations: Interleukin ( IL), T-helper ( Th), human gingival fibroblasts ( HGFs), indoleamine 2,3-dioxygenase ( IDO), monoclonal antibodies ( mAbs), intercellular adhesion molecule ( ICAM)1, interferon ( IFN)-gamma, tumor necrosis factor ( TNF)-alpha, mean fluorescence intensity ( MFI).