Objective: To evaluate the expression of C-C motif chemokine ligand 5 (CCL5) in hepatocellular carcinoma (HCC) and to explore its role in regulating the immune microenvironment and the related mechanism in tumor immunity.
Methods: The mRNA expression level of CCL5 in HCC and adjacent non-cancerous tissues was measured by quantitative polymerase chain reaction and the protein expression was examined by immunohistochemistry. Serum CCL5 expression was measured by an enzyme-linked immunosorbent assay (ELISA). C57BL/6 wild-type (WT) and Ccl5-knockout (Ccl5-/- ) mice were utilized to conduct the diethylnitrosamine-induced HCC model. The immune cell population was determined by flow cytometry, and peripheral serum immunoglobulin M (IgM) level was quantified by ELISA.
Results: CCL5 expression was low in HCC tissue and peripheral blood compared with adjacent non-cancerous tissues or controls, and its expression was correlated with the overall survival, cancer recurrence and distant metastasis. In the HCC mouse model, liver-to-body weight ratio was of the Ccl5-/- group were higher than that of the WT group. Moreover, compared with the WT mice, the number of B cells in the tumor tissue of the Ccl5-/- mice was lower, while there were no significant differences in the other immune cell populations. Furthermore, serum IgM level of the Ccl5-/- mice was significantly lower than that of the WT mice.
Conclusion: CCL5 expression is decreased in HCC tissues. CCL5 deficiency reduces B cell recruitment and decreases IgM secretion in HCC, potentially leading to tumor progression.
Keywords: B cell recruitment; chemokine CCL5; disease progression; hepatocellular carcinomaimmunoglobulin M.
© 2021 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.