Changes Of Peripheral Blood Monocytes And MDSC Subsets And Their Clinical Significance In Patients With Oral Squamous Cell Carcinoma

[Background]Oral squamous cell carcinoma(OSCC)is the most common invasive epithelial tumor in oral and maxillofacial regions,and its incidence is increasing year by year.Although OSCC has adopted comprehensive treatment methods including surgery,radiotherapy and chemotherapy,the five-year survival rate of OSCC patients has unsatisfyingly lingered low at～60%over the paet 30 years.There are many reasons for not achieving satisfactory results,and the lack of an effective early diagnosis method is one of the factors that cannot be ignored.At present,the diagnosis of OSCC rely mainly on physical examination and histopathologic examination,OSCC diagnosis with these methods is often in middle and late stage.What’s more,histopathologic examination could cause a certain degree of pain to the patients.Therefore,it is urgent to look for OSCC diagnostic markers that are easy to observe and have no damage to patients.Monocytes and myeloid-derived suppressor cells(MDSC)play important roles in the occurrence and development of many tumors.However,their role in oral cancer has not been widely reported.Our previous study have found that OSCC patients had abnormal circulating white blood cells.However,the changes and significance of monocytes and MDSC subsets in OSCC were not elucidated.As a relatively safe and less traumatic method in routine clinical examinations,blood sample is of great value in early diagnosis of OSCC.Therefore this study through the detection of the ratio changes of peripheral blood mononuclear cell and MDSC subsets and the expression of their receptor on the surface.The characteristics of each test index in OSCC patients and its correlation with clinical parameters were analyzed,and the diagnostic value of OSCC was evaluated.[Purpose]The purpose of this study is to detect peripheral blood monocytes and their subsets ratio,MDSC subsets ratio,CCR2 expression level in monocytes,their subsets,MDSC subsets and their correlation with clinical parameters,and to assess the value of the proportion of peripheral blood monocytes and their subsets and MDSC subsets as diagnosis biomarkers for OSCC.[Methods]1.The frequencies of monocyte subsets in peripheral blood of 68 OSCC patients and 57 healthy donors were determined by flow cytometry,and compared between groups.We analyzed the correlation between monocytes and their subsets and clinical parameters,and evaluated their diagnostic value for OSCC.2.The frequencies of monocyte subsets in peripheral blood of 64 OSCC patients and 35 healthy donors were determined by flow cytometry,and compared between groups.We analyzed the correlation between MDSC subsets and clinical parameters,and evaluated their diagnostic value for OSCC.3.The CCR2 expression level of monocytes and their subsets and MDSC subsets in peripheral blood of 67 OSCC patients and 24 healthy donors were determined by flow cytometry,and compared between groups.We analyzed the correlation between the CCR2 expression level of monocytes and MDSC subsets and clinical parameters.[Results]1.Flow cytometry detection results showed:compared with healthy controls,the percentage of monocytes of peripheral blood mononuclear cells(PBMC)in peripheral blood of OSCC patients increased significantly(P<0.05);the percentage of CD 14++CD16+(intermediate)monocyte subsets were significantly higher than that in healthy controls(P<0.0001).There was no significant change between,the percentage of CD 14++CD16-(classical)monocyte subsets and CD 14+CD16++(nonclassical)monocyte subsets(P>0.05).The percentage of monocytes were correlated with the gender,smoking habit and the depth of invasion(DOI);the percentage of CD14++CD16+(intermediate)monocyte subsets were correlated with worst pattern of invasion(WPOI).ROC curve analysis results showed:the area under the curve(AUC)of ROC curves for intermediate monocytes was 0.810(95%confidence interval[CI]=0.735-0.886,P<0.0001)with diagnostic sensitivity(73.5%)and specificity(78.9%)at a cut-off value of 5.81%.When conducted combined analyses of the percentage of intermediate monocytes with total monocytes,classical monocytes or nonclassical monocytes,the AUCs of ROC curves were 0.817(P<0.0001),0.816(P<0.0001)and 0.811(P<0.0001),repectively.These data indicated that the frequency of intermediate monocytes could be a potential diagnostic biomarker to identify OSCC patients from healthy subjects.2.Flow cytometry detection results showed:compared with healthy controls,the percentage of M-MDSC(monocyte MDSC)of MDSC in peripheral blood of OSCC patients increased significantly(P<0.05),the percentage of G-MDSC(granulocyte MDSC)did not change significantly.The percentage of M-MDSC was correlated with DOI.ROC curve analysis results show:the AUCs of ROC curves for M-MDSC was 0.691(95%confidence interval[CI]=0.589-0.793,P<0.002)with diagnostic sensitivity(45.9%)and specificity(89.6%)at a cut-off value of 31.4%.When conducted combined analyses of the percentage of G-MDSC,the AUCs of ROC curves was 0.731(P<0.0001).These data indicated that the frequency of M-MDSC could be a potential diagnostic biomarker to identify OSCC patients from healthy subjects.3.Flow cytometry detection results showed:compared with healthy controls,the percentage of monocytes and G-MDSC surface CCR2 expression in peripheral blood of OSCC patients increased significantly(P<0.0001,P<0.0001,respectively),and they were all correlated with DOI.[Conclusion]CD14++CD 16+(intermediate)monocytes and the M-MDSC ratio in the peripheral blood of OSCC patients increased significantly,and were correlates with WPOI and DOI.They could be a potential diagnostic factor for OSCC,could provide experimental basis for clinical non-invasive diagnosis of OSCC.In addition,the expression of CCR2 on the surface of CD14+CD16++(non-classical)monocytes and G-MDSC increased significantly in OSCC patients,and was closely related to DOI,suggesting that these two types of cells affect the invasion of OSCC.