Are periodontal fibroblasts target cells for lipoxins and resolvin D1?
Lipoxins and resolvins are endogenous eicosanoids which participate in the resolution of inflammation. The connective tissue, including the fibroblasts of the periodontal ligament and the gingiva, is inflamed in periodontal disease. However, it is unknown if periodontal fibroblasts are targeted by lipoxins and resolvins. This study has investigated the impacts of lipoxin A4, lipoxin B4, and resolvin D1 on the response of periodontal ligament fibroblasts and gingival fibroblasts to the inflammatory mediators interleukin (IL)-1b and tumor necrosis factor-a (TNF-a) and platelet-derived growth factor BB (PDGF-BB). It was found that up to a concentration of 1 mM neither of the eicosanoids changed the expression of IL-6 and IL-8 by periodontal fibroblasts previously exposed to IL-1b and TNF-a. The eicosanoids also failed to modulate IL-1b-induced phosphorylation of p38 and c-Jun N-terminal protein kinase signaling molecules. Furthermore, lipoxins and resolvin D1 did not change proliferation rates or protein synthesis by periodontal fibroblasts exposed to PDGF-BB. Together, these results suggest that the response of periodontal fibroblasts to inflammatory mediators and a potent mitogen is not modulated by lipoxins and resolvin D1 under the in vitro conditions studied.