Effect of microRNA-7 knockdown on peripheral immune cell composition in DSS-induced murine ulcerative colitis model
Objective To determine whether microRNA-7(miRNA-7,miR-7)alters the proportion of immune cells in peripheral immune organs such as the spleen and mesenteric lymph nodes(MLNs),in dextran sulfate sodium salt(DSS)-induced ulcerative colitis(UC)mice,and to explore its initial significance.Methods An a-cute UC model was established in miR-7 knockdown(KD)transgenic mice using DSS.The morphology and weight of the spleen and MLNs,as well as the total cell numbers,were observed;flow cytometry(FCM)was performed to identify the proportions of adaptive immune cells(CD19+B cells,CD4+T cells and CD8+T cells)and innate immune cells(Gr-1+neutrophils,CD11b+cells,NK1.1+T cells,CD11c+dendritic cells,F4/80+macrophages and γδ T cells)in spleen and MLNs of the peripheral immune organs in mice,and to cal-culate the absolute cell numbers.Results Compared to wild-type(WT)UC model mice,miR-7KD UC model mice exhibited significantly larger spleens and MLNs,with a notable increase in both weight and cell number(P＜0.05).There was a significant increase in CD4+T cells,CD8+T cells,and CD19+B cells among them(P＜0.05).The results of HE staining showed that,compared to the WT UC model mice,the miR-7KD UC model mice exhibited dilated and congested splenic sinuses and reduced spleen nodules.Additionally,the mesenteric lymph nodes in the miR-7KD UC model mice displayed significantly enlarged lymphoid follicles and expanded medullary and cortical areas.In miR-7 knockdown mice,the number of CD4+T cells,CD8+T cells,and CD19+B cells in the spleen and MLNs significantly increased,with the differences being statistically significant(P＜0.05).Additionally,the numbers of innate immune cells,including Gr-1+neutrophils,CD11b+cells,CD11c+dendritic cells,F4/80+macrophages,and γ8T cells,were also significantly elevated(P＜0.05).Conclusion miR-7 knockdown significantly altered the composition of immune cells in the spleen and MLNs of peripheral immune organs in mice,suggesting that miR-7 may mediate the pathological damage in UC by affect-ing the changes of peripheral immune cells.These findings provide preliminary data for understanding the patho-genesis of clinically relevant inflammatory diseases,such as UC.
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