肝脏肿瘤诱导髓源抑制性细胞的肝脏趋化及诱导肝内免疫抑制作用机制的研究

Immune suppressor mechanisms such as Tregs or MDSCs during hepatocellular carcinoma (HCC ) progression are being uncovered. We showed here the critical role of liver stroma in the process of MDSCs accumulation and tumor progression in HCC. .Methods: Murine hepatoma cells were injected subcutaneously to BALB/c mice with or without liver stromal cells to obtain tumor-bearing mice. Purified MDSCs were labeled with CFSE or DiR for in vivo migration assay. Liver stromal cells were used to mimic the liver microenvironment for in vitro chemotaxis assay. Neutralizing antibodies were employed for in vivo and in vitro blockade. Immunohistochemistry was performed to detect pathological injury and inflammation in liver and tumor tissue. .Results: Adoptively transferred MDSCs accumulated mainly into liver and partially in spleen both in normal mice and tumor-bearing mice. Interestingly, much more adoptively transferred MDSCs accumulated into liver site in tumor-bearing mice than that in tumor-free mice as confirmed by flow cytometry and living image. Adoptively transferred MDSCs also accumulated in tumor tissues in tumor-bearing mice. MCP-1 and SDF-1 expressed at high level in liver stromal cells. We examined the expression of MCP-1 and SDF-1 in liver stromal cells after exposure to heaptoma cell-cultured supernatant and found an increased expression of the two chemokines. In vitro chemotaxis assay showed liver stromal cell derived factors promote MDSCs migration which could be reversed by MCP-1 and SDF-1 neutralizing antibodies. Liver stromal cells also promote hepatoma growth when co-injected with tumor cells, which may be attributed to increased MDSCs accumulation as detected by living image. Tumor growth could be significantly reduced in vivo by MCP-1 and SDF-1 neutralization. Besides, in HCC patients, tumor associated stroma cells and CD11b+ myeloid cells are highly enriched in peri-tumor tissues, which is accompanied by high expression of MCP-1 and SDF-1 . .Conclusions: These results demonstrate that liver stromal cells promote MDSCs migration via SDF-1 and MCP-1 in hepatoma-bearing mice and thus foster tumor progression. Understanding the cross-talk between liver stroma and MDSCs in HCC may provide a promissing breakthrough for further immunotherapeutic strategies.

肝基质细胞作为肝脏间质的重要组成部分，在肝脏原位肿瘤的生长中发挥重要作用，但其机制尚不明确。有关乳腺癌的研究报道，肿瘤相关基质细胞可通过分泌一些趋化因子，趋化肿瘤相关免疫抑制性细胞如肿瘤相关单核细胞及肿瘤相关中性粒细胞，进而促进肿瘤的生长。关于原发性肝细胞癌的最新研究报道，肿瘤组织内的趋化因子CXCL5与肿瘤相关中性粒细胞（TANs）成正相关，并与患者预后明显相关。鉴于MDSCs与DCreg 来源于共同髓系祖细胞（CMP）以及上述的前期研究结果，我们推测肝脏基质细胞可以诱导骨髓前体细胞分化为抑制性MDSCs。大量肿瘤驱动产生的MDSCs在肝基质细胞的趋化作用下向肝脏聚集，进而抑制宿主的抗肿瘤免疫反应，促进肿瘤逃避机体免疫攻击。

肝基质细胞作为肝脏间质的重要组成部分,在肝脏原位肿瘤的生长中发挥重要作用,但其机制尚不明确。有关乳腺癌的研究报道,肿瘤相关基质细胞可通过分泌一些趋化因子,趋化肿瘤相关免疫抑制性细胞如肿瘤相关单核细胞及肿瘤相关中性粒细胞,进而促进肿瘤的生长。关于原发性肝细胞癌的最新研究报道,肿瘤组织内的趋化因子CXCL5与肿瘤相关中 性粒细胞(TANs)成正相关,并与患者预后明显相关。鉴于MDSCs与DCreg 来源于共同髓系祖细胞(CMP)以及上述的前期研究结果,我们推测肝脏基质细胞可以诱导骨髓前体细 胞分化为抑制性MDSCs。大量肿瘤驱动产生的MDSCs在肝基质细胞的趋化作用下向肝脏聚集 ,进而抑制宿主的抗肿瘤免疫反应,促进肿瘤逃避机体免疫攻击。本课题对肝基质细胞对MDSCs的趋化和诱导分化进行深入研究，最终探讨这种作用的关键影响因素。明确了肝基质细胞对MDSCs趋化和体外诱导分化机制，进一步验证了用MDSCs过继回输治疗免疫介导肝损伤的应用假设。本研究就肝基质细胞对MDSCs的免疫调控作用进行研究，为MDSCs用于免疫介导肝损伤的治疗提供了前期理论基础。