Changes in intestinal microbiota and phenotypes of immune cells in mice with atherosclerosis and arthritis / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the changes in intestinal microbiota and immune cells in mice with atherosclerosis and arthritis. Methods Two groups were set up with 8-week-old ApoE knockout (ApoE-/ -) and C57BL/ 6 mice. All mice were fed with high fat diet. The severity of atherosclerosis was evaluated through analyzing the level of serum lipid by ELISA and arteriosclerotic plaques by oil red O stai-ning. K/ BxN serum was intraperitoneally injected into ApoE-/ - and C57BL/ 6 mice at 17 to 26 weeks of age until 26 weeks to induce arthritis. The development of arthritis in mice was evaluated with vernier caliper-measured ankle width and clinical score. Total DNA was extracted from fecal samples of mice to amplify the 16S V4 region by PCR, and then sequencing analysis was performed on Illumina HiSeq PE250. Splenocytes and bone marrow cells were isolated and stained by antibodies to analyze the changes in immune cell distribu-tion by flow cytometry. Results The levels of low density lipoprotein cholesterol (LDL-C) and total choles-terol (TCHO) in serum and the atherosclerotic plaques in aorta were significantly increased in ApoE-/ - mice than in C57BL/ 6 mice, suggesting that the symptoms of atherosclerosis in ApoE-/ - mice were more severe than those in C57BL/ 6 mice. Ankle width measurements and clinical scores of arthritis showed that the ApoE-/ - mice had less severe ankle swelling than the C57BL/ 6 mice. Moreover, the ApoE-/ - mice had de-creased intestinal microbiota diversity, especially in the number of Verrucomicrobiae. Flow cytometry analy-sis showed that CD3+T and CD19+B cells were down-regulated, while CD11b+ macrophages were up-regula-ted in splenocytes and bone marrow cells of the ApoE-/ - mice. Conclusions Immune cell distribution was changed in the ApoE-/ - mice with atherosclerosis and arthritis. Compared with the C57BL/ 6 mice, the ApoE-/ - mice had decreased intestinal microbiota diversity and altered bacterial composition. Moreover, the abundance of Akkermansia, a potential biomarker of healthy intestinal environment, in the ApoE-/ - mice was also decreased. It was suggested that the changes in intestinal microbiota might be involved in the pathogene-sis of atherosclerosis complicated by arthritis.