[Study of immunophenotypic characteristics, clinicopathological parameters and prognosis in gastric cancer...

Objective: To explore the immunophenotypic characteristics of gastric cancer microenvironment and analyze its correlation with clinicopathological parameters and prognosis of patients. Methods: The expression levels of leukocyte differentiation antigen (CD) 8, CD4, T lymphocyte immunoglobulin mucoprotein 3 (TIM3), human forkhead box protein P3 (Foxp3) and co-localized tumor infiltrating lymphocytes (TILs) were detected in 92 cases of gastric cancer tissue [58 males and 34 females; aged M(Q₁, Q₃), 70(59, 77) years ] and 84 cases of paracancer tissue [57 males and 27 females, aged 70(59, 77) years] purchased from Shanghai Xinchao Biotechnology Co., Ltd., and the samples were from 28 hospitals in the sample bank. Gastric cancer and adjacent tissues were divided into high expression group and low expression group according to the optimal cut-off value of positive lymphocytepercentage. The expression of immunophenotypes in gastric cancer and adjacent tissues was analyzed. Kaplan-Meier method was used for survival analysis. Cox proportional hazard model was used to explore the prognostic factors of gastric cancer patients. Results: The optimal cut-off values of CD8, CD4, TIM3 and Foxp3 positive cells in gastric cancer were 12.73%, 1.39%, 10.77% and 2.44%, respectively. The expression of Foxp3 in gastric cancer tissues was higher than that in paracancer tissues [M (Q), 0.93 (0.45, 2.16) vs 0.31 (0.09, 0.86), P<0.001], and the expression of CD8 [4.92 (2.34, 8.80) vs 8.81 (6.61, 12.17), P<0.001], CD4 [4.79 (1.77, 11.36) vs 8.40 (4.84, 12.77), P=0.022] and TIM3 [5.68 (2.05, 11.58) vs 7.07 (3.13, 11.43), P=0.338] were lower than that in paracancer tissues. There were significant differences in TIM3 expression in gastric cancer patients with different lymph node metastasis and clinical stage (all P<0.05). The 5-year survival rate of patients with high CD4 expression, low TIM3 expression and low Foxp3 expression in gastric cancer tissues was poor, among which the high CD4 expression and low CD4 expression groups were 29.3% and 64.7%, respectively; The high and low TIM3 expression groups were 60.9% and 30.4%, respectively; The high and low Foxp3 expression groups were 64.3% and 33.3%, respectively (all P<0.05). The optimal cut-off values of CD8⁺TIM3⁺TILs, CD4⁺TIM3⁺TILs, CD8⁺Foxp3⁺TILs and CD4⁺Foxp3⁺TILs were 3.86%, 0.23%, 0.08% and 0.76%, respectively. Colocalization analysis showed that the expression of CD8⁺Foxp3⁺TILs in gastric cancer tissues was higher than that in adjacent tissues(all P<0.05). Multivariate Cox regression analysis showed that high expression of CD4 (HR=3.079, 95%CI: 1.350-7.024,P=0.008), low expression of TIM3 (HR=0.428, 95%CI: 0.208-0.879, P=0.021) and low expression of Foxp3 (HR=0.288, 95%CI: 0.121-0.687, P=0.005) were the influencing factor for the 5-year survival rate of patients with gastric cancer after operation. Conclusions: Gastric cancer tissues have complex immune microenvironment characteristics. The expression of CD4, TIM3 and Foxp3 is closely related to the prognosis of patients.