Influence Of Different Ratio Of Dietary Fat And Dietary Cholesterol On The Level Of CD4~+CD25~+Foxp3~+regulatory T Cells In Rats

0bjective Based on the function and the amount of regulatory T cells, and theirchanges in rats with different ratio of dietary fat and dietary cholesterol, this study isto investigate the immunomodulatory effect of regulatory T cells in NAFLD.Methods Fifty rats were randomly divided into five groups: control group, low-fatdiet group, high-fat diet group, low-fat and cholesterol diet group and high-fat andcholesterol diet group. All rats were killed at the end of the twentieth week, extractedfasting venous blood for ALT, AST, TC, TG, HDL-C, LDL-C and flow cytometry forthe proportion of peripheral blood CD4~+CD25~+Foxp3~+regulatory T cells in CD4~+Tcells, pathological changes were recorded by hematoxylin-eosin staining and Foxp3gene expression was detected by reverse transcription-polymerase chain reaction(RT-PCR) and western blot.Results1. Hematoxylin-eosin staining indicated that the control group presented ten casesof normal liver, the low-fat diet group presented three cases of normal liver and sevencases of low-grade fatty liver, while the high-fat diet group presented six cases oflow-grade fatty liver and four cases of moderate fatty liver, the low-fat and cholesteroldiet group and high-fat and cholesterol diet group presented one death and three casesof moderate fatty liver and sixteen cases of high-grade fatty liver, eleven cases withinflammation and necrosis of liver cells.2. Compared with control group, the proportion of peripheral bloodCD4~+CD25~+Foxp3~+regulatory T cells in CD4~+T cells in low-fat diet group wassignificantly increased(P<0.01), and in high-fat diet group was decreased with nosignificant difference（P>0.05）,while in low-fat and cholesterol diet group and high-fat and cholesterol diet group were significantly decreased (P<0.01). Significantdifference was observed among low-fat diet group, high-fat diet group and low-fatand cholesterol diet group (P<0.01). No significant difference was observed betweenlow-fat and cholesterol diet and high-fat and cholesterol diet group (P>0.05).Compared with low-fat diet group, the proportion in low-fat and cholesterol dietgroup was significantly decreased. Compared with high-fat diet group, the proportionin high-fat and cholesterol diet group was significantly decreased.3. Compared with control group, Foxp3mRNA levels in low-fat diet group wassignificantly increased (P<0.01), and in high-fat diet group was decreased with nostatistical significance (P>0.05), while in low-fat and cholesterol diet group andhigh-fat and cholesterol diet group were significantly decreased (P<0.01). Significantdifference was observed among low-fat diet group, high-fat diet group and low-fatand cholesterol diet group (P<0.01). No significant difference was observed betweenlow-fat and cholesterol diet and high-fat and cholesterol diet group (P>0.05).Compared with low-fat diet group, the proportion in low-fat and cholesterol dietgroup was significantly decreased. Compared with high-fat diet group, the proportionin high-fat and cholesterol diet group was significantly decreased.4. Compared with control group, expression of Foxp3in low-fat diet group wassignificantly increased (P<0.01), and in high-fat diet group was decreased with nostatistical significance (P>0.05), while in low-fat and cholesterol diet group andhigh-fat and cholesterol diet group were significantly decreased (P<0.01). Significantdifference was observed among low-fat diet group, high-fat diet group and low-fatand cholesterol diet group (P<0.01). No significant difference was observed betweenlow-fat and cholesterol diet and high-fat and cholesterol diet group (P>0.05).Compared with low-fat diet group, the proportion in low-fat and cholesterol dietgroup was significantly decreased. Compared with high-fat diet group, the proportionin high-fat and cholesterol diet group was significantly decreased.Conclusion1. High dietary cholesterol may play a vital role in the pathogenesis of NASH, dietary fat together with dietary cholesterol interact synergistically to induce thedevelopment of deterioration of steatosis, inflammation and necrosis of liver cells.2. The expression of Foxp3in liver and the proportion of CD4~+CD25~+Foxp3~+regulatory T cells in CD4~+T cells in peripheral blood will increase in rats withlow-grade steatosis, while the level of CD4~+CD25~+Foxp3~+regulatory T cells willreduce in moderate steatosis, and reduce further in high-grade steatosis. Thedecrease of regulatory T cells was correlated to the grade of steatosis.