Inulin-type fructan improves diabetic phenotype and gut microbiota profiles in rats

Qian Zhang; Hongyue Yu; Xinhua Xiao; Ling Hu; Fengjiao Xin; Xiaobing Yu

doi:10.7717/peerj.4446

Inulin-type fructan improves diabetic phenotype and gut microbiota profiles in rats

PeerJ. 2018 Mar 1:6:e4446. doi: 10.7717/peerj.4446. eCollection 2018.

Authors

Qian Zhang^#¹, Hongyue Yu^#², Xinhua Xiao¹, Ling Hu², Fengjiao Xin³, Xiaobing Yu⁴

Affiliations

¹ Key Laboratory of Endocrinology, Translational Medicine Center, Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
² Department of Endocrinology, Shanxi Provincial People's Hospital, Taiyuan, China.
³ Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China.
⁴ Fengning Ping'an High-tech Industrial Co., Ltd., Hebei Province, China.

^# Contributed equally.

Abstract

Background & aims: Accumulating research has addressed the linkage between the changes to gut microbiota structure and type 2 diabetes (T2D). Inulin is one type of soluble dietary fiber that can alleviate T2D. As a prebiotic, inulin cannot be digested by humans, but rather is digested by probiotics. However, whether inulin treatment can benefit the entire gut bacteria community remains unknown. In this study, we evaluated the differences in gut microbiota composition among diabetic, inulin-treated diabetic, normal control, and inulin-treated normal control rats.

Methods: A diabetic rat model was generated by a high-fat diet and streptozotocin injections (HF/STZ). Inulin was orally administered to normal and diabetic rats. To determine the composition of the gut microbiota, fecal DNA extraction and 16S rRNA gene 454 pyrosequencing were performed.

Results: We found that inulin treatment reduced fasting blood glucose levels and alleviated glucose intolerance and blood lipid panels in diabetic rats. Additionally, inulin treatment increased the serum glucagon-like peptide-1 (GLP-1) level, reduced serum IL-6 level, Il6 expression in epididymal adipose tissue, and Pepck, G6pc expression in liver of diabetic rats. Pyrophosphate sequencing of the 16s V3-V4 region demonstrated an elevated proportion of Firmicutes and a reduced abundance of Bacteroidetes at the phylogenetic level in diabetic rats compared to normal control rats. The characteristics of the gut microbiota in control and inulin-treated rats were similar. Inulin treatment can normalize the composition of the gut microbiota in diabetic rats. At the family and genus levels, probiotic bacteria Lactobacillus and short-chain fatty acid (SCFA)-producing bacteria Lachnospiraceae, Phascolarctobacterium, and Bacteroides were found to be significantly more abundant in the inulin-treated diabetic group than in the non-treated diabetic group. In addition, inulin-treated rats had a lower abundance of Desulfovibrio, which produce lipopolysaccharide (LPS). The abundance of Lachnospiraceae was negatively correlated with the blood glucose response after a glucose load.

Conclusion: In summary, diabetic rats have different gut microbiota from control rats. Inulin treatment can alleviate gut microbiota dysbiosis in T2D model rats. Moreover, inulin treatment enhanced serum GLP-1 level to suppress IL-6 secretion and production and hepatic gluconeogenesis, resulted in moderation of insulin tolerance.

Keywords: Diabetes; Gut microbiota; Inulin; Soluble fiber.

Grants and funding

This work was supported by the National Key R&D Program of China (2017YFC1309603), the National Key Research and Development Program of China (2016YFA0101002), the National Natural Science Foundation of China (81170736, 81570715), the National Natural Science Foundation for Young Scholars of China (81300649), the China Scholarship Council Foundation (201308110443), the PUMC Youth Fund (33320140022), the China Diabetes Young Scientific Talent Research Funding, Fundamental Research Funds for the Central Universities, and the Scientific Activities Foundation for Selected Returned Overseas Professional of Human Resources and Social Security Ministry. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.