The regulation of dietary lamb on the macrophage polarization in mice with ulcerative colitis
Objective:To study the effect of lamb on macrophage polarization in mice with ulcerative colitis(UC)induced by dextran sodium sulfate(DSS)and provide a theoretical basis for the dietary regimen of UC pa-tients.Methods:Thirty-two healthy female C57βL/6 mice with SPF grade were randomly divided into control group,DSS group,low-dose lamb group,medium-dose group and high-dose lamb group.The mice in the control group ate and drank freely throughout the process.The DSS group and the low,medium and high dose group of lamb were free to drink 2.5％(w/v)DSS solution for 5 days and deionized water for 7 days for 1 cycle,repeated 3 cycles to establish a chronic UC model.Take the start of giving DSS solution as day 1,started to gavage lamb sus-pension of 0.25 g/mL,0.50 g/mL,1.00 g mL dose on day 6.The DSS group was given the same amount of dei onized water,during which the general condition,weight,and stool of all groups were recorded every day.Colon tissue was retained after the intervention and the degree of pathological damage was assessed by H&E staining and histopathological scoring evaluation.Spleen tissue was collected to prepare single-cell suspension and the level of M1 and M2 macrophages was measured by flow cytometry and the content of TNF-α,IL-6,IL-10,TGF-β,ZO-1,E-cadherin mRNA were detected by RT-qPCR.Results:Compared with the control group,UC mice showed different degrees of weight loss,diarrhea and bloody stool.Compared with the DSS group,the weight of mice in each dose group of lamb decreased significantly(P＜0.01 or P＜0.05)and DAI showed an increasing trend,among which there were statistical differences in the middle and high-dose group(P＜0.05).Compared with the DSS group,the degree of pathological damage of the colon of mice in each dose group of lamb showed an increasing trend,and there were statistical differences in the middle and high dose group(P＜0.01).The colonic tight junction-associated proteins ZO1 and E-cadherin mRNA in each dose group of lamb showed a decreasing trend and there were differences in the medium and high dose group(P＜0.01).Compared with the DSS group,the content of M1 macrophages in the spleen of mice in each dose group of lamb was significantly increased(P＜0.01 or P＜0.05).The content of M1 macrophage-associated inflammatory factors TNF-α and IL-6 mRNA showed an increasing trend and there were statistical differences in the high-dose group(P＜0.01).The content of M2 macrophages was significantly reduced(P＜0.01)and the content of M2 macrophages-associated inflammatory factors IL-10 and TGF-β mRNA decreased(P＜0.01 or P＜0.05).Conclusion:Dietary lamb can damage the mu-cosal barrier and aggravate the intestinal inflammation of UC and its mechanism is related to promoting the differ-entiation of macrophages to M1 cells and inhibiting the differentiation to M2 cells,thereby aggravating the imbal-ance of M1/M2 macrophages.
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