The role and mechanism of myeloid-derived suppressor cells in mice with nonalcoholic steatohepatitis / 中国医师杂志

ABSTRACT

Objective To investigate the effects of myeloid-derived suppressor cells (MDSCs) on nonalcoholic steatohepatitis mice.Methods (1) Male C57BL/6 mice aged 6-8 weeks were randomly divided into normal diet group,CDAA group(choline deficient amino acid diet) and CSAA group (choline sufficient amino acid diet).(2) After the success of the non-alcoholic steatohepatitis model,serum was collected from some mice to detect biochemical indexes;Liver tissue was retained for microscopic observation by hematoxylin-eosin (HE) staining;The changes of T cell subsets in peripheral blood of mice in each group were detected by flow cytometry.In addition,The proportion and subtype of CD1 lb + Gr-1 + MDSCs cells in liver,spleen,blood and bone marrow were also detected by flow cytometry.(3)The bone marrow-derived Gr-1highLy-6G+ was purified by magnetic bead sorting technique,and the purified Gr-1highLy-6G+ was transferred into non-alcoholic steatohepatitis (NASH) mice by tail vein injection.The role of MDSCs in NASH was analyzed by detection of serological indexes of liver function and pathological dyeing.Results (1) There was no significant difference in body weight and liver index between the groups (P ＞ 0.05).Serological indicatorsalanine aminotransferase (ALT),aspartate aminotransferase (AST),blood glucose,interleukin (IL)-6 and interferon-γ (INF-γ) in the model group were significantly higher than those in the normal group (P ＜ 0.01);microscopic findings:the liver in CDAA,CSAA group showed varying degrees of steatosis;the steatosis in CDAA group was much more severe.(2) Flow cytometry showed that ① the percentage of CD4 + CD8-T and CD4-CD8 + T decreased and CD4/CD8 ratio decreased in CDAA group;② the bone marrow MDSCs of CDAA group is lower than that of normal group (P ＜ 0.05);the MDSCs of peripheral blood in CDAA group is lower than that of normal group (P ＞ 0.05);the MDSCs of liver in CDAA group is lower than that of normal group (P ＜ 0.01).③ subgroup comparison,bone marrow,liver CD11 b + Gr-1 high Ly-6G + (G-MDSC)CDAA group ＞ normal group (P ＜ 0.0l),CD11 b + Gr-1 dim Ly-6G-(M-MDSC) showed a downward trend,CDAA group ＜ normal group;(3) Serum AST and ALT levels of NASH mice who receiving Gr-1highLy-6G+ MDSCs from normal bone marrow were significantly decreased (P ＜ 0.001),and histopathological changes were alleviated.Conclusions (1) The NASA mouse model can be successfully established on the CDAA diet.(2) The CDAA-induced NASH mice may have immune dysfunction,mainly manifesting in the change of bone marrow MDSCs subpopulations and the increase of CDllb + Gr-1highLy-6G+ (G-MDSC).(3) MDSCs derived from normal mouse bone marrow can alleviate the pathological changes of NASH.