The programmed-death-ligand-1 (PD-L1) is an immune-modulating molecule that is constitutively expressed on various immune cells, different epithelial cells and a multitude of cancer cells. It is a costimulatory molecule that may impair T-cell mediated immune response. Ligation to the programmed-death-receptor (PD)-1, on activated T-cells and further triggering of the related signaling pathways can induce T-cells apoptosis or anergy. The upregulation of PD-L1 in various cancer types, including oral squamous cell carcinomas, was demonstrated and has been linked to immune escape of tumors and poor prognosis. A bidirectional relationship exists between the increased PD-L1 expression and periodontitis as well as the epithelial–mesenchymal transition (EMT), a process of interconversion of epithelial cells to mesenchymal cells that may induce immune escape of tumors. Interaction between exosomal PD-L1 and PD-1 on T-cells may cause immunosuppression by blocking the activation and proliferation of T-cells. The efficacy and importance of treatment with PD-1/PD-L1 checkpoint inhibitors and their prognostic influence on human cancers was demonstrated. Regarding PD-1/PD-L1 checkpoint inhibitors, resistances exist or may develop, basing on various factors. Further investigations of the underlying mechanisms will help to overcome the therapeutic limitations that result from resistances and to develop new strategies for the treatment of cancer.

中文翻译：

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程序性死亡受体 （PD-）1/PD 配体 （L）1 在牙周炎和癌症中的作用


程序性死亡配体-1 （PD-L1） 是一种免疫调节分子，在各种免疫细胞、不同的上皮细胞和多种癌细胞上组成性表达。它是一种共刺激分子，可能会损害 T 细胞介导的免疫反应。与活化 T 细胞上的程序性死亡受体 （PD）-1 连接并进一步触发相关信号通路可诱导 T 细胞凋亡或无反应。PD-L1 在各种癌症类型（包括口腔鳞状细胞癌）中的上调已被证明与肿瘤的免疫逃逸和不良预后有关。PD-L1 表达增加与牙周炎以及上皮-间充质转化 （EMT） 之间存在双向关系，EMT 是上皮细胞向间充质细胞相互转化的过程，可能诱导肿瘤的免疫逃逸。外泌体 PD-L1 和 PD-1 对 T 细胞的相互作用可能通过阻断 T 细胞的活化和增殖而引起免疫抑制。证明了 PD-1/PD-L1 检查点抑制剂治疗的疗效和重要性及其对人类癌症的预后影响。关于 PD-1/PD-L1 检查点抑制剂，基于各种因素，存在或可能产生耐药性。对潜在机制的进一步研究将有助于克服耐药性导致的治疗限制，并开发治疗癌症的新策略。