Integrated OMICS Study of the Beneficial Effects of Egg Shell Membrane-derived Resistant Protein on Intestinal Bacteria

2020 Fiscal Year Annual Research Report

• Project/Area Number: 20F20401
• Research Institution: The University of Tokyo
• Principal Investigator: 加藤 久典 東京大学, 大学院農学生命科学研究科(農学部), 特任教授 (40211164)
• Co-Investigator(Kenkyū-buntansha): YANG YONGSHOU 東京大学, 農学生命科学研究科, 外国人特別研究員
• Project Period (FY): 2020-11-13 – 2023-03-31
• Keywords: eggshell membrane / Profiber / resistant proteins / high-fat diet; / metabolic dysfunctions / gut microbiota / metabolites

Outline of Annual Research Achievements

Consumption of resistant proteins (RP) has been reported to exert beneficial functions including anti-obesity, hypolipidemic, and anti-colon diseases. However, the involvement of gut microbiota in such beneficial effects is not fully elucidated. Eggshell membrane (ESM) and sake cake (commercial name is Profiber: PFB) contain a large amount of RP. Here, we performed the first animal experiment to investigate the effects of dietary ESM or PFB on metabolic dysfunctions and gut dysbiosis induced by high-fat diet (HFD). A total of 48 C57BL6J male mice was assigned randomly to the following six dietary groups: (1) Control diet (Ctrl), (2) high-fat diet (HFD), (3) HFD with 8% ESM (HESM), (4) HFD with 8% ESM+ antibiotics mix (ESMAbx), (5) HFD with 30% PFB (HPFB), (6) HFD with 30% PFB + antibiotics mix (PFBAbx). Compared with Ctrl group, mice fed an HFD showed increased body weight, visceral fat mass, liver weight, liver triglycerides, and liver cholesterol. Compared with the HFD group, the mice body weight gains were reduced in both of HESM and ESMAbx groups. However, the mice body weight gains were not affected in HPFB and PFBAbx groups compared that in the HFD group. The oral glucose tolerance test was not affected in these treatment groups. PFB treatment reduced the level of cholesterol in serum and liver. Compared with the Ctrl group, HFD showed increased level of immunoglobulin (IgA) in colon content. ESM treatment did not affect IgA level in colon content compared with that of HFD group. PFB treatment was shown to slightly increase the IgA level in colon content.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

Currently, we are trying to analyze the metabolites of gut microbiota, such as organic acids in the cecal contents. The total bacterial DNA in cecal contents was extracted and 16S rRNA gene sequencing will be performed in the near future.
Additionally, I am performing an animal experiment to examine consumption of sericin on the effects of gut environment in high-fat fed rats. Silk sericin is abundant in silk industry waste, and it was considered as a promising natural protein due to its indigestible and other functional properties.

Strategy for Future Research Activity

1. Analysis the collected data from the animal experiments performed previously: 1) analyze the fecal bacteria by performing 16S rRNA gene amplicon sequencing; 2) measure the biomarkers in serum and microbial metabolites in the cecal content.
2. Exploration of bacterial species in the gut responsible for anti-inflammatory effects of ESM-RP via ex vivo antibiotics treatment. For ex vivo fecal microbiota transplantation (FMT), C57BL6/J mice will be divided into two groups. HFD-fed mice (Donor) supplemented with or without ESM-RP for 8 weeks. During week 6 to week 8 (total of 14 days), fecal microbiota from each donor mouse is collected daily, treated with antibiotics, pooled, mixed and stored at -80 °C. HFD-fed mice (Recipient) will be treated daily with FMT from each donor group via oral gavage for 8 weeks.