Direct CCL4 Inhibition Modulates Gut Microbiota, Reduces Circulating Trimethylamine N-Oxide, and Improves Glucose and Lipid Metabolism in High-Fat-Diet-Induced Diabetes Mellitus

Ting-Ting Chang,1– 3 Jaw-Wen Chen1– 6 1Department and Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan; 2Department and Institute of Pharmacology, National Yang Ming Chiao Tung University, Taipei, Taiwan; 3School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; 4Healthcare and Services Center, Taipei Veterans General Hospital, Taipei, Taiwan; 5Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; 6Cardiovascular Research Center, National Yang Ming Chiao Tung University, Taipei, TaiwanCorrespondence: Jaw-Wen ChenHealthcare and Services Center, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of ChinaTel +886-2-28757730Fax +886-2-28757703Email jwchen@vghtpe.gov.tw; iwchen99@gmail.comPurpose: Modulation of the gut microbiota may lead to changes in pathological conditions. C-C chemokine motif ligand (CCL) 4 was upregulated in diabetes mellitus (DM) and was shown to play a significant role in pancreatic inflammation and glucose metabolism. The detailed in vivo mechanisms have not been well explored. This study aimed to investigate the hypothesis that direct CCL4 inhibition could modify gut microbiota and systemic metabolism in diet-induced DM mice.Methods: C57BL/6 mice fed a high-fat diet (HFD) were used as a diet-induced DM model. CCL4 inhibition was conducted by anti-CCL4 neutralizing monoclonal antibodies. The gut microbiota was analyzed by high-throughput sequencing of the 16S rRNA. Fecal microbiota transplantation (FMT) was used to verify the effect of CCL4 deficiency on gut microbiota and the linkage between CCL4-modulated gut microbiota and HFD-induced DM.Results: CCL4 inhibition stabilized glucose homeostasis, modulated lipid parameter, and decreased inflammatory markers in HFD-induced DM mice. Moreover, CCL4 inhibition reversed HFD-induced gut dysbiosis, evidenced by the decreased abundance of family Muribaculaceae and increased abundance of family Atopobiaceae when CCL4 antibodies were administrated. CCL4 inhibition led to a decrease in circulating trimethylamine N-oxide levels, a proinflammatory metabolite from gut microbiota. Taken together, CCL4 inhibition could modify gut microbiota profiles, suppress proinflammatory metabolites, reduce systemic inflammation, improve insulin resistance, and retard the progression of hyperglycemia in HFD-induced DM. Furthermore, FMT from CCL4 knockout mice rescued the glucose homeostasis in HFD-induced DM mice.Conclusion: Our findings may not only provide a novel rationale to in vivo CCL4-based therapeutic approach in diet-induced DM but also indicate the significance of gut microbiota profile including the family Muribaculaceae and the family Atopobiaceae as a potential modifiable target for systemic metabolism.Keywords: diabetes mellitus, gut microbiota, inflammation, chemokine, trimethylamine N-oxide