背景：Tol 样受体4及其配体脂多糖与牙周疾病的发生、发展密切相关，牙周膜干细胞的免疫学特性在牙周组织修复重建、牙周病的治疗中发挥重要作用，而Tol 样受体4及其配体对牙周膜干细胞免疫学特性的影响还不清楚。目的：探讨Tol 样受体4对牙周膜干细胞免疫学特性的影响。方法：分离、培养牙周膜干细胞，与10 mg/L的Tol 样受体4配体脂多糖共同培养3 d。以未经脂多糖处理的牙周膜干细胞作为对照，观察脂多糖处理的牙周膜干细胞能否引起同种异体淋巴细胞的增殖，以及对混合淋巴细胞反应和植物血凝素引起的淋巴细胞增殖的影响。通过建立Transwel 培养系统建立牙周膜干细胞+植物血凝素+异体外周血单个核细胞的反应体系，测定细胞上清液中的前列腺素E2浓度。在上述反应体系进行中和实验，观察被牙周膜干细胞抑制了的淋巴细胞重新发生增殖的情况。结果与结论：无论是否与脂多糖共培养，牙周膜干细胞都没有引起等量异体外周血单个核细胞增殖，都能够抑制植物血凝素引起的淋巴细胞增殖和混合淋巴细胞反应，但是脂多糖预处理牙周膜干细胞的免疫抑制作用显著低于无脂多糖组。在牙周膜干细胞+植物血凝素+异体外周血单个核细胞的反应体系中，前列腺素 E2浓度显著升高。中和实验发现，前列腺素E2的拮抗剂吲哚美辛基本恢复了被牙周膜干细胞抑制的淋巴细胞增殖。提示，脂多糖减弱了牙周膜干细胞的免疫抑制特性，该效应由前列腺素E2减少引起。%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.
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