The Immunological Characteristics And Function Of CD103~+ CD8~+ Tissue Resident T Cells In ESCC

Esophageal cancer(EC)is one of the fastest developing malignancies,about 90%of EC cases are esophageal squamous cell carcinoma(ESCC).Although there are multidisciplinary treatments,such as surgery,chemotherapy and radiotherapy for ESCC,the current 5-year global survival is still poor of around 30-40%.Immunotherapy is one of the most effective methods for tumor elimination,especially adoptive transfer of tumor infiltrating lymphocytes(TILs).CD8+TILs immunotherapy has been rapidly developed as a therapy for tumors,containing ESCC,and it has also been the most important element for patient survival.However,it remains unclear whether there is different sub-population in CD8+TILs that might contribute to the superior outcome,which leads to a variety of clinical responses among ESCC patients.Recently,tissue-resident memory(TRM)T cells have attracted great attention.TRM cells can elicit direct cytotoxicity to infected host cells by effector cytokine production,and are involved in regulating anti-tumor immune response.It was reported that CD103+CD8+TILs were closely related to survival rate of patients,however,there were not enough available data to show the presence of CD103+CD8+TRM cells in human ESCC tissues,and their roles in the anti-tumor immune reaction.Therefore,a better understanding of the sub-population of CD103+CD8+T cells is helpful to discover new biomarkers and identify more effective therapeutic strategy that are more relevant to tumor diagnosis,treatment,and prognosis.To investigating whether CD103+ CD8+TRM cells are presented in ESCC,Ⅰ-ⅣESCC TCGA data of RNA-sequencing(RNA-Seq)were analyzed,and fresh surgical samples were confirmed via flow cytometry.CD103-CD8+ TRM cells were present in ESCC,with high expression of CD69,PD-1,TIM-3,and very low expression of CD62L/CCR7,which suggested that CD103+CD8+TRM cells exist in ESCC and may be the main effector cells in tumor immunity.In addition,in order to understand whether the proportion and phenotype of CD103+CD8+TRM cells were affected by chemotherapy,fresh surgical samples of patients with neoadjuvant chemotherapy were used.The proportion and phenotype of CD103+ CD8+ TRM cells in patient with neoadjuvant chemotherapy were consistent with the expression trend in that of naive patients,and there was no statistical difference between neoadjuvant chemotherapy patients and naive patients.Next,samples of untreated ESCC were selected to comprehend the relationship between CD103+CD8+TILs and clinical prognosis through immunohistochemistry.It was found that high expression of CD103+and CD8+T cells was associated with better prognosis of ESCC.To find the specific function of CD103+CD8+TRM cells in ESCC,we used ESCC fresh tissue specimens to observe the proliferation of Ki67 and production of IFN-γ,IL-2 in CD 103+CD8+TRM cells.The result showed that CD 103+CD8+ TRM cells had strong proliferation and more IFN-y,IL-2 secretion.In addition,the secretion of IFN-y and IL-2 in CD103+TRM cells was increased after blockaded by anti-PD-1 antibody.In order to fully study the effects of anti-PD-1 drug intervention on CD103+CD8+TRM cells,we used the 4-NQO-induced EC mouse model to observe the change of CD103+CD8+TRM cells after anti-PD-1 antibody treatment.The results showed that the number of CD103+T cells infiltrated in tumor tissues was increased and the number of tumors was significantly decreased after EC mice were treated with anti-PD-1.Finally,4-NQO-induced EC mice were used as the research object,differential transcriptome genes in CD103+ CD8+T cells and CD103-CD8+T Cells were explored with RNA-seq.The results showed that the functional enrichment of differential genes in CD 103+CD8+cells were mainly reflected in cytotoxicity,cellular immune response,cell adhesion function and related signaling pathways,which were consistent with previous studies and indicated that CD103+ cells might be related with the immune response.Collectively,this study identified CD 103 as a biomarker of tumor reactive CD8+TILs,and demonstrated that CD103+ CD8+TILs were represented as tumor resident memory T cell sub-population in ESCC.It can elicit potent anti-tumor immunity after anti-PD-1 blockade,and was not affected by neoadjuvant chemotherapy.In conclusion,we suggested that CD103 was a suitable marker to evaluate the antitumor immune response about CD8 T cell infiltration of ESCC through freshly isolated patient TIL and 4-NQO-induced mouse model of ESCC,which might be a notable biomarker for immunotherapy alone or in combination with either anti-PD-1 blockade or chemotherapy.