负性调控骨髓间充质干细胞的FAPα- - 增强多发性骨髓瘤疫苗抗瘤效应的新策略

The immunosuppressive microenvironments seriously limit the clinical applications of multiple myeloma (MM) therapeutic vaccines. Previous studies have demonstrated that tumor-derived bone mesenchymal stem cells (BMSCs) have a major role in immune suppression. The stromal cell-derived fibroblast activation protein-alfa (FAPα) contribute to the resistance of an immunogenic tumor to therapeutic vaccination. From our pilot experiments, MM-derived BMSC (MM-BMSC) which express FAPα could inhibit the T cell proliferation and reduce the anti-MM immune responses induced by dendritic cell (DC) vaccine. So we make hypothesis that FAP expressed by MM-BMSC is probably a key, novel target to break immune tolerance and enhance vaccine efficacy in MM. .To test that, we will systematic study the MM-BMSC function on immune suppression and on inhibition of anti-tumor activities of MM-DC vaccine. In addition, we will further explore the possibilities of reversing the "vaccine resistance" due to MM-BMSC by the means of the FAPαdown-regulation. This project will contribute to uncover the molecular mechanism of immune tolerance in MM microenvironment, enhance anti-tumor activities of MM vaccine in vivo and improve the poor prognosis.

体内微环境的免疫抑制状态是限制多发性骨髓瘤（MM）疫苗临床应用的重要瓶颈。最新研究表明，肿瘤源性骨髓间充质干细胞（BMSC）具有免疫抑制功能，肺癌动物模型中成纤维细胞活化蛋白α（FAPα）能削弱疫苗抗瘤效应。据此我们进行预试验，初步发现MM源性BMSC（MM-BMSC）通过FAPα抑制T细胞增殖并削弱MM树突状细胞（DC）疫苗的抗瘤效应，推测FAPα可能是MM-BMSC介导免疫耐受、降低疫苗效力的关键新调控点。.为验证假设，本课题拟通过体内外实验系统研究MM-BMSC的免疫负调节功能及其对MM-DC疫苗抗瘤活性的影响，明确FAPα在其中的关键核心作用及其机制，初步探讨负性调控FAPα逆转MM-BMSC介导的"疫苗抵抗"这一新策略的有效性。本课题的实施有助于揭示肿瘤微环境中MM产生免疫耐受的新机制，为切实提高MM疫苗体内的抗瘤活性，改善MM患者的不良预后提供新思路。

微环境中的T细胞亚群免疫抑制状态形成是多发性骨髓瘤（MM）发生免疫逃逸的重要机制。肿瘤源性骨髓间充质干细胞（BMSC）对多种T细胞具有免疫抑制功能，肺癌动物模型中成纤维细胞活化蛋白α（FAPα）能削弱疫苗抗瘤效应。我们前期预试验发现MM源性BMSC（MM-BMSC）通过FAPα抑制T细胞增殖，推测FAPα可能是MM-BMSC通过负性调节T细胞介导免疫逃逸的关键新调控点。本项目以肿瘤微环境中MM-BMSC为切入点，通过体外实验和临床资料分析，系统研究MM-BMSC在体外对多种T细胞亚群的免疫负调节功能，明确FAPα在其中的重要作用及其机制。. 我们研究证实，FAPα高表达于MM-BMSC；在与Naïve T细胞的共培养环境中，MM-BMSC不仅可以抑制CD4+ T细胞的增殖，促进CD4+ T细胞的衰老，也可诱导Th17/Treg平衡向Th17漂移；还可抑制CTL的杀伤活性，显示出显著地的免疫负调节活性。FAPα特异性抑制剂PT-100促进MM-BMSC表达分泌TGF-β、IL-6和G-SCF；在共培养体系中PT-100削弱了MM-BMSCs对T细胞的免疫负调节作用：促进CD4+ T细胞的增殖，减少CD4+ T细胞的衰老，诱导Th17/Treg平衡向Treg漂移，还增强CTL的杀伤活性，表明FAPα是MM-BMSC负性调节多种T细胞亚群的关键调控点。MM-BMSC表达的TGF-β和IL-6可能是FAPα介导MM-BMSC免疫负调节活性的重要机制。负性调控FAPα有望成为改善MM免疫逃逸与逆转免疫耐受的新方法。. 本课题的实施有助于揭示肿瘤微环境中MM产生免疫逃逸和免疫耐受的新机制，探寻MM免疫治疗的新策略。