TCF4调控巨噬细胞表型极化介导慢性非可控炎症的机制研究

Macrophage plays an important role in the development of liver cancer, but the roles of different phenotypes of macrophages in chronic non-resolving inflammation are unclear. In our previous study, we found CD11b（high）F4 / 80（low）Ly6C（high） macrophages (M1a) were specifically increased in non-resolving inflammation. Besides, we found that M1a is characteristics of proinflammatory cytokines secretion, cell adhesion and proliferation. Further we used bioinformatics method to analysis the enrichment of transcription factors of M1a differential genes, and the results showed that TCF4 may participate in the regulation of M1a formation. Based on the above information, we propose a scientific hypothesis: viral infection or exogenous injury induces TCF4 activation in macrophage and results in M1a phenotype, which can secret proinflammatory cytokines IL-6, TNF-α , IL-1β. In this way, M1a maintains chronic non-resolving inflammation and promotes liver cancer initiation. The main research contents are as following: (1) the orgin and characteristics of M1a in non-resolving inflammation; (2) the molecular mechanism of TCF4 in regulation of M1a; (3) the role and mechanism of M1a in the development of chronic non-resolving inflammation. This subject will clarify macrophage mediated chronic non-resolving inflammation and provide new ideas for the early screen and immunotherapy of liver cancer.

巨噬细胞在肝癌发生发展中发挥重要作用，然而不同表型的巨噬细胞在慢性非可控炎症和肝癌发生中的作用尚不清楚。申请者前期研究发现，CD11bhighF4/80lowLy6Chigh巨噬细胞（M1a）在慢性非可控炎症中特异性增加，且M1a具有促炎因子分泌、细胞粘附和增殖特征。利用生物信息学分析M1a差异基因富集的转录因子，发现TCF4极有可能参与调控M1a的形成。基于以上信息，本课题提出科学假设：病毒感染或外源性损伤活化巨噬细胞TCF4，使巨噬细胞M1a极化，分泌促炎因子IL-6、TNF-α、IL-1β等维持慢性非可控炎症促进肝癌发生。主要研究内容：（1）慢性非可控炎症中M1a来源及特征；（2）TCF4调控M1a分子机制；（3）M1a在慢性非可控炎症中的作用及机制。本课题将阐明巨噬细胞在慢性非可控炎症介导肝癌发生中的作用及机制，为肝癌的早期发现和免疫治疗提供新的思路。

肿瘤相关巨噬细胞(Tumor associated macrophages, TAMs)是肿瘤微环境(Tumor microenvironment, TME)的重要组成成分，约占肿瘤间质免疫细胞的50%以上。在大多数实体瘤的TME中，TAMs的组成以具有免疫抑制能力的巨噬细胞为主，在肿瘤免疫抑制性微环境的形成中发挥重要作用。本项目基于TAMs的转录组学特征，研究TAMs免疫抑制功能形成的机制。主要包括以下三方面研究内容：1. 三羧酸循环旁路代谢酶L2HGDH（L-2-羟基戊二酸脱氢酶）在TAM中的表达及其对肿瘤预后的影响；2. L2HGDH及其代谢底物S-2HG对巨噬细胞表型的调控作用及其机制研究；3. S-2HG处理的巨噬细胞对PD-1抗体治疗黑色素瘤的影响。研究结果显示，L2HGDH在TAM中高表达并影响肿瘤患者预后，L2HGDH缺失促进巨噬细胞M1极化，L2HGDH缺失及S-2HG处理的巨噬细胞抑制肿瘤生长。机制研究表明S-2HG但并非R-2HG处理的巨噬细胞抑制肿瘤生长，并且α-KG能逆转S-2HG处理的巨噬细胞的抗肿瘤作用。S-2HG处理的巨噬细胞能够增加PD-1抗体肿瘤治疗敏感性。以上结果表明靶向巨噬细胞L2HGDH可逆转肿瘤免疫抑制性微环境，并增加PD-1抗体治疗应答率。该研究为临床肿瘤免疫治疗提供新策略。