Effect of Toll-like receptor 4 on the immunological properties of periodontal ligament stem cells / 中国组织工程研究

ABSTRACT

BACKGROUND:Tol-like receptor 4 (TLR4) and its ligand, lipopolysaccharid, are closely associated with the occurrence and development of periodontitis. Meanwhile, the immunological properties of periodontal ligament stem cells (PDLSCs) play an important role in the reconstruction of periodontal tissue and cel-based therapy of periodontitis. However, the effect of TLR4 and lipopolysaccharid on the immunological properties of PDLSCs remains unclear. OBJECTIVE:To investigate the effect of TLR4 on the immunological characteristics of human PDLSCs. METHODS:PDLSCs were isolated by enzyme digestion method as previously reported, and were cultured in the medium containing 10 mg/L lipopolysaccharid, the ligand of TLR4 for 3 days. Using un-treated PDLSCs as controls, we then investigated whether lipopolysaccharid-treated PDLSCs could cause the proliferation of al ogeneic T lymphocytes as wel as the effect of lipopolysaccharid-treated PDLSCs on the mixed lymphocytes reaction and proliferation of lymphocytes induced by phytohemagglutinin. PDLSCs, peripheral blood mononuclear cells and phytohemagglutinin were co-cultured, and the concentration of prostaglandin E2 in the culture supernatant was examined. Then we added indomethacin, which is the inhibitor of prostaglandin E2, into the co-culture system of PDLSCs, peripheral blood mononuclear cells and phytohemagglutinin, and tested the proliferation of lymphocytes. RESULTS AND CONCLUSION:Lipopolysaccharid-treated PDLSCs did not lead to the proliferation of al ogeneic T lymphocytes just as un-treated PDLSCs, and could suppress the mixed lymphocytes reaction and proliferation of phytohemagglutinin-induced lymphocytes. However, the inhibitory ability of lipopolysaccharid-treated PDLSCs was significantly lower than that of un-treated PDLSCs. The levels of prostaglandin E2 were significantly elevated in the co-culture of PDLSCs, peripheral blood mononuclear cells and phytohemagglutinin. After adding of indomethacin, the PDLSCs-suppressed proliferation of lymphocytes restored to normal levels. Lipopolysaccharid weakened the immunosuppressive capacity of PDLSCs, which may be due to the decreasing secretion of prostaglandin E2.