Conelation Research Between The Expression Of Myeloid-derived Suppressor Cells And The Degree Of Inflammation In Acute Ulcerative Colitis Mice Model

Aim:To find a possible evaluation index and therapeutic target,we investigate the correlation between the expression of myeloid-derived suppressor cells(MDSCs)and the inflammation degree of acute ulcerative colitis(UC)mice model.Methods:Acute UC models of C57BL/6 mice with different severity of intestinal inflammation were constructed by 3%and 4%dextran sulfate sodium(DSS).Disease activity index(DAI)was recorded.The mice were sacrificed on the 7th day,the length of colon was measured,and the histological pathology score of colon was assessed.The expressions of TNF-α,IL-1β and IL-6 in colons were measured by RT-qPCR,and the relationship between the pathological process of UC and these inflammatory cytokines was discussed.On this basis,the expression of CD11b+Grl+MDSC in bone marrow and blood was tested by flow cytometry.To explore the correlation between the expression of MDSCs and the degree of inflammation in acute UC mice model,the correlation analysis was conducted between the expression ratio of MDSC and weight loss ratio,colon length and colon pathology score.Results:1.Compared with control group,the DAI score of d7(P<0.01),histopathological score(P<0.01)and weight loss ratio(P<0.01)in 3%DSS groups significantly increased.At the same time,the DAI score of d7(P<0.01),histopathological score(P<0.05)and weight loss ratio(P<0.01)in 4%DSS groups were higher than control group.In addition,the DAI score of d7(P<0.01),histopathological score(P<0.05)and weight loss ratio(P<0.05)in 4%DSS groups were higher than 3%DSS group.Compared with control group,3%DSS group(P<0.0001)and 4%DSS group(P<0.0001)mice showed significant colon shortening.In addition,colon shortening was more obvious in the 4%DSS group than 3%DSS group((P<0.01).2.Compared with control group,the expression levels of TNF-α(P<0.01),IL-1β(P<0.05)and IL-6(P<0.05)in mice colon of 3%DSS group significantly increased.At the same time,the expression levels of TNF-α(P<0.05),IL-1β(P<0.01)and IL-6(P<0.05)in mice colon of 4%DSS group were higher than those in control group.In addition,the expression level of TNF-α,IL-1β and IL-6 in mice colon of 4%DSS group were higher than those in 3%DSS group,but the difference was not statistically significant(P>0.05).3.Compared with control group,the proportion of peripheral blood MDSC in 3%DSS group(P<0.01)and 4%DSS group(P<0.01)significantly increased.In addition,the proportion of peripheral blood MDSC in 4%DSS group was higher than 3%DSS group(P<0.05).Compared with control group,the proportion of peripheral blood MDSC in 3%DSS group(P<0.01)and 4%DSS group(P<0.05)significantly decreased.However,there was no significant difference between the 3%DSS group and the 4%DSS group(P=0.129).4.The proportion of MDSC in peripheral blood of acute UC mice was positively correlated with the proportion of weight loss(P<0.05)and pathological score(P<0.05),but negatively correlated with colon length(P<0.05).There was no correlation between bone marrow MDSC ratio and colon pathology score,weight loss degree,colon length(P>0.05).Conclusion:The proportion of MDSC in peripheral blood of acute UC groups are higher than normal group,and the proportion of MDSC is higher in the group with severe colitis.The proportion of MDSC in bone marrow of acute UC groups are lower than normal group,but there is no significant difference between the model groups with different intestinal inflammation degree.The proportion of MDSC in peripheral blood of acute UC mice model was positively correlated with colonic pathological score and weight loss ratio,and negatively correlated with colonic length,which was a possible auxiliary indicator for clinical judgment of UC colitis activity.