Expression of tumor-associated macrophages and PD-L1 in patients with hepatocellular carcinoma and construction of a prognostic model
Authors: kong Panpan , Yang Huan , Tong Qing , Dong Xiaogang , Yi Mamumaimaitijiang-Abula , Yan Dong 
Published: March 2023

Abstract
Background: Hepatocellular carcinoma (HCC) is an inflammation-associated tumor involved in immune tolerance and evasion in the immune microenvironment. Immunotherapy can enhance the body's immune response, break immune tolerance, and then recognize and kill tumor cells. The polarization homeostasis of M1 and M2 macrophages in tumor microenvironment (TME) is involved in the occurrence and development of tumor, which is a hot topic in tumor research. Programmed cell death ligand 1 (PD-L1) plays an important role in the polarity of TAM and affects the prognosis of HCC patients as a target of immunotherapy. Therefore, we further explored the application value of PD-L1, M1 macrophages (CD86) and M2 macrophages (CD206) in the prognosis assessment of HCC, their correlation with immune cell infiltration in HCC tissues, and their bioenrichment function.
Methods: The gene expression omnibus (GEO) and The Cancer Genome Atlas (TCGA) database were used to analyze the expression of PD-L1, CD86 and CD206 in different tumor tissues. The Tumor Immune Estimation Resource (TIMER) was used to analyze the correlation between the expression of PD-L1, CD86 and CD206 and the infiltration of immune cells. The tissue specimens and clinicopathological data of hepatocellular carcinoma patients who underwent surgical treatment in our hospital were collected. Immunohistochemistry was used to verify the expression of PD-L1, CD86 and CD206, and analyze the relationship with clinicopathological features and prognosis of patients. Nomogram was constructed to predict the overall survival (OS) of patients at 3 and 5 years. Finally, STRING database was used to analyze the protein-protein interaction network information, and GO analysis and KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis were performed to study the biological functions of PD-L1, CD86 and CD206.
Result:Bioinformatics analysis found that PD-L1, CD86 and CD206 were all under-expressed in a variety of tumor tissues including liver cancer, while our immunohistochemical analysis found the opposite result, and PD-L1, CD86 and CD206 were all over-expressed in liver cancer tissues. The expressions of PD-L1, CD86 and CD206 were positively correlated with the level of immune cell infiltration in HCC tissues; The expression of PD-L1 is positively correlated with the degree of tumor differentiation; The expression level of CD206 was positively correlated with gender and whether patients had hepatitis before operation. The prognosis of patients with low expression of PD-L1 or CD86 is poor. AJCC stage, preoperative hepatitis, and the expression level of CD206 in adjacent tissues are independent risk factors affecting the survival of patients after radical hepatectomy. KEGG pathway enrichment analysis showed that PD-L1 was significantly enriched in T cell aggregation and lymphocyte aggregation, and may be involved in the formation of T cell antigen receptor CD3 complex and cell membrane. CD86 was significantly enriched in positive regulation of cell adhesion, regulation of mononuclear cell proliferation, regulation of leukocyte proliferation and transduction of T cell receptor signaling pathway. CD206 was significantly enriched in type 2 immune response, cellular response to LPS, cellular response to LPS, and involvement in cellular response to LPS.
Conclusion: In conclusion, these results suggest that PD-L1, CD86 and CD206 may not only be involved in the occurrence and development of HCC, but also in immune regulation. Therefore, PD-L1, CD86 and CD206 can be used as potential biomarkers and new therapeutic targets for HCC prognosis assessment.