Stromal infiltration of lymphocytes and expression of immune checkpoint genes in early esophageal cancer patients with different stages

Objective To investigate lymphocyte interstitial infiltration condition and the changes of immune checkpoint gene expression in different stages of early esophageal cancer.

Methods A retrospective analysis was conducted on the clinical data of 90 patients with early esophageal cancer. Based on the pathological depth of infiltration, they were divided into three types: T1a-M1, T1a-M2, and T1a-M3, with 30 cases in each type. Additionally, 30 cases of paired normal mucosa tissues adjacent to the cancer were selected. Hematoxylin-eosin (HE) staining was used to observe tissue morphology. Immunohistochemistry was employed to detect the expression of CD3, CD4, CD8, and CD20. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was applied to measure the mRNA expression levels of immune checkpoint genes programmed death ligand-1 ( PD-L1 ), cytotoxic T-lymphocyte-associated protein 4 ( CTLA4 ), T-cell immunoglobulin and mucin domain-3 ( TIM-3 ), lymphocyte activation gene 3 ( LAG3 ), programmed death receptor-1 ( PD-1 ), programmed death ligand-2 ( PD-L2 ), and T-cell immunoreceptor with Ig and ITIM domains protein (TIGIT).

Results As the stage of early esophageal cancer progressed, the ratio of tumor cells to lymphocytes increased. The number of CD3⁺ T cells was greater than that of CD20⁺ B cells, and the proportion of CD4⁺ T cells among total T cells was higher than that of CD8⁺ T cells (P < 0.001). The mRNA expression levels of gene in immune checkpoints in patients were elevated (P < 0.05). Compared with normal adjacent tissues, the expression levels of PD-L1 mRNA, CTLA4 mRNA, TIM-3 mRNA, PD-1 mRNA, and TIGIT mRNA were elevated in patients with T1a-M1, T1a-M2, and T1a-M3 types (P < 0.05). Compared with normal adjacent tissues, the expression levels of LAG3 mRNA and PD-L2 mRNA were increased in patients with T1a-M2 and T1a-M3 types (P < 0.05).

Conclusion The progression of early esophageal cancer staging is correlated with increased immune checkpoint gene expression and a decreased lymphocyte ratio, suggesting that changes in the immune microenvironment may be involved in tumor progression.