Wnt3a is a central regulator for P. gingivalis-mediated expression of PD-L1 and suppression of CD8+ T cell activity

摘要 程序性死亡配体-1（PD-L1）的阻断显示出患者的显著临床结局 癌症或慢性感染通过重振耗尽的CD8 + T细胞反应。然而，只有一个小 部分患者对这种治疗反应良好，这表明迫切需要深入了解 PD-L1的功能和调节机制。最近的突破性发现表明，PD-L1的表达 树突状细胞（DC）上的免疫调节对于PD-L1/PD-1阻断免疫疗法的功效至关重要。卟 牙龈炎（Pg）是慢性牙周炎和组织损伤的病原体。感染Pg 据报道，可加重癌症进展并促进肿瘤细胞中的PD-L1表达。然而，如果和 Pg感染如何促进DC上PD-L1的表达及其对CD8 + T细胞活性的可能影响 仍然完全未知。因此，鉴定新的免疫信号传导调节剂是诱人的，其可以 调节PD-L1的表达并影响细胞毒性T细胞活性，长期目标是恢复免疫功能。 系统在监视和消除入侵生物体和癌细胞中的功能。我们最近的研究 表明Pg感染强烈增加先天免疫中Wnt（Winglesss and Int-1）3a的表达， 细胞和Wnt3a负调节先天免疫反应的强度。我们的初步数据显示 Pg感染（i）显著增强BMDCs上PD-L1的表达，并损害同种异体BMDCs的细胞毒性， 抗原特异性CD8 + T细胞;（ii）显著增强Wnt3a的表达，并且抑制Wnt3a降低 PD-L1在BMDC上的表达;和（iii）导致Yes相关蛋白1（雅普）和WW-1的增加。 含结构域的转录调节因子-1（TAZ）表达，但上游激酶减少 DCs中的磷酸化。由于雅普/TAZ显示与PD-L1表达相关并与Wnt 3a相互作用， 在其他情况下，我们假设Wnt3a是一种重要的免疫调节剂， PD-L1表达并通过调节活化抑制Pg刺激后的CD8 + T细胞活性 雅普/TAZ信号转导及其下游转录增强因子（TEA）-结构域家族的DNA- 结合因子1（TEAD 1）。我们将通过两个具体目标来证明这一假设：（1）：建立角色 Wnt3a作为Pg诱导的PD-L1和CD8 + T细胞活性损伤的内源性调节剂; (2)确定Wnt3a是否通过以下途径促进Pg诱导的PD-L1表达和CD8 + T细胞活性受损： 修饰雅普/TAZ及其下游TEAD 1的活性。该项目的成功实施将（一） 绘制了一个新的和潜在的关键信号通路（Wnt3a-YAP/TAZ-TEAD 1），并确定了更多 PD-L1表达的干预靶点;和（ii）极大地帮助理解调控机制 Pg感染损害了CD8 + T细胞的细胞毒性，这将为开发创新的 通过操纵Wnt 3 - 3的活性来控制癌症和慢性感染的免疫调节疗法 雅普/TAZ的相关性应远远超出口腔。

Abstract Blockade of program death ligand-1 (PD-L1) is demonstrating remarkable clinical outcomes for patients with cancer or chronic infection through reinvigorating exhausted CD8+ T cell responses. However, only a small portion of patients can respond well to this treatment, indicating a dire need for an in-depth understanding of the function and regulatory mechanisms of PD-L1. Recent breakthrough findings revealed that expression of PD-L1 on dendritic cells (DCs) is critical for the efficacy of PD-L1/PD-1 blockade immunotherapy. Porphyromonas gingivalis (Pg) is a causative agent of chronic periodontal inflammation and tissue damages. Infection with Pg was reported to aggravate cancer progression and promote PD-L1 expression in tumor cells. However, if and how Pg infection promotes expression of PD-L1 on DCs and its possible effect on CD8+ T cell activity remain entirely unknown. Thus, it is tempting to identify novel immune signaling modulators that can regulate expression of PD-L1 and impact cytotoxic T cell activity, with a long-term goal of restoring the immune system function in surveillance and elimination of invaded organisms and cancer cells. Our recent studies demonstrated that Pg infection robustly increases expression of Wnt (Winglesss and Int-1) 3a in innate immune cells and Wnt3a negatively regulates the intensity of innate immune responses. Our preliminary data suggest that Pg infection (i) significantly enhances PD-L1 expression on BMDCs and impairs cytotoxicity of allogenic antigen-specific CD8+ T cells; (ii) remarkably enhances expression of Wnt3a, and inhibition of Wnt3a reduces expression of PD-L1 on BMDCs; and (iii) leads to an increase of Yes-associated protein 1(YAP) and WW- domain-containing transcription regulator-1(TAZ) expression but a decrease of an upstream kinase phosphorylation in DCs. Since YAP/TAZ was shown to associate with PD-L1 expression and interact with Wnt3a signaling in other contexts, we thus hypothesize that Wnt3a is a critical immunomodulator that promotes PD-L1 expression and suppresses CD8+ T cell activity upon stimulation with Pg by regulating activation of YAP/TAZ signaling and its downstream transcriptional enhancer factor (TEA)-domain family of DNA- binding factor 1 (TEAD1). We will demonstrate this hypothesis with two specific aims: (1): Establish the role of Wnt3a as an endogenous regulator of the Pg-induced PD-L1 and impairment of CD8+ T cell activity; (2) Establish if Wnt3a promotes Pg-induced PD-L1 expression and impairment of CD8+ T cell activity via modifying the activity of YAP/TAZ and its downstream TEAD1. Successful completion of this project will (i) maps out a novel and potentially critical signaling pathway (Wnt3a-YAP/TAZ-TEAD1) and identifies more interventional targets in PD-L1 expression; and (ii) greatly aids in understanding the regulatory mechanism that Pg infection impairs CD8+ T cell cytotoxicity, which will pave the way for the development of innovative immunoregulatory therapies for the control of cancer and chronic infections via manipulating activity of Wnt3- YAP/TAZ that should have relevance well beyond oral cavity.