The Research Of The Mechanism Of PD-L1/PD-L2 Role In The Cutaneous Squamous Cell Carcinoma Immune Escape

Objective:To detect the expression of PD-L1/PD-L2 in cancer tissue sample of CSCC patients,as well as the infiltration of different mature state of LCs, while analyze its correlation with clinical indexes and discuss the relationship between the expression of PD-L1/PD-L2 on LCs within foci tissue of CSCC patients with the immune escape, aim to reveal the mechanism of PD-1 signaling pathway involved in the CSCC immune escape and provide a new target of immune intervention for its diagnosis and treatment.Methods:We used immunohistochemical staining, flow cytometry technique,immunofluorescence and qRT-polymerase chain reaction(PCR) methods to compare the different expression of PD-L1/PD-L2 and IL-10 in CSCC tumor tissue, paraneoplastic, and normal tissues, as well as the different expression levels of PD-L1/PD-L2 on the different mature state of LCs. 61 cases of tumor tissue sections of CSCC patients, at the same time keep some part of paraneoplastic tissue sections, and 17 cases of normal healthy human skin tissue corresponding to the age as control group.And for the relationship between the expression level of PD-L1/PD-L2 in CSCC with the patient’s age, gender, tumor size,pathologicalgrading, whether located on the exposed parts, and whether there is lymph node metastasis were statistically analyzed.Results:1. All of the tumor tissue sections of CSCC patients, the positive rates of PD-L1 was40.98%(25/61); and the positive rates ofPD-L2 was 60.66%(37/61), and the expression of these two were significantly correlated, the results indicated that the expression of PD-L1 and PD-L2 in foci tissue of CSCC patients were upregulated significantly.2.There are a large number of LCs cells infiltration in the PD-L1- and PD-L2-positive tissue sections, and the proportion of immature LCswas significantly increased.3.The proportion of PD-L1/PD-L2 expression on CD1a+LCs was significantly higher than the expression proportion on CD83+LCs.4.The expression of PD-L1/PD-L2 in CSCC was not related with the patient’s age and gender, the expression levels of PD-L1/PD-L2 were not statistically significant with tumor size, whether located on the exposed parts, whether there is lymph node metastasis,pathological grading, and other risk factors.5. The expression of IL-10 and PD-L1/PD-L2 wereupregulated, IL-10 might be involved in the regulation of CSCC immune escape.Conclusion:PD-L1/PD-L2 may through inhibiting the mature LCs that in turn mediates the immune escape of tumor cells of CSCC patients, but the specific mechanism is not clear yet.