May 21, 2024
Kitasato University
Keio University
A research group from Kitasato University and Keio University has discovered that insufficient water intake worsens the gut environment and reduces the ability to eliminate pathogenic bacteria.
This study is the result of research by Professor Tomoki Kimbara of the Department of Microbiology, Faculty of Pharmacy, Kitasato University (at the time of the research, a professor at the Center for Drug Discovery, Faculty of Pharmacy, Keio University); Kensuke Sato, a third-year student in the Doctoral Programs of the Graduate School of Media and Governance and the Institute for Advanced Biosciences at Keio University; Visiting Professor Jo Inoue of the Department of Biochemistry, Faculty of Pharmacy at the same university; and Professor Masato Yasui and Associate Professor Mariko Chikuma of the Department of Pharmacology, School of Medicine at the same university.
Water is an extremely vital substance for life, making up over 50% of the body and playing various roles such as digestion and absorption, transport of nutrients and waste products, and body temperature regulation. Although a lack of water intake has been reported to be associated with the onset of metabolic diseases and premature death, its effects on the intestines, particularly the gut microbiota and immune system, were not well understood. Therefore, the researchers decided to conduct a detailed analysis of the gut environment when water intake was restricted.
This study revealed that water restriction disrupts the homeostasis of the gut environment and reduces the ability to eliminate pathogenic bacteria. Mice with restricted water intake developed constipation, accompanied by delayed intestinal transit time and reduced fecal output. Furthermore, water restriction altered the composition of the gut microbiota and increased the total number of intestinal bacteria. On the other hand, it was found that Th17 cells, a type of immune cell involved in the defense response against pathogenic bacteria, decreased, leading to a delay in the elimination of intestinal pathogenic bacteria. Moreover, a significant reduction in Th17 cells was observed in the large intestine of mice lacking Aquaporin 3 (AQP3), a protein responsible for transporting water into cells. These findings indicate that sufficient water intake is a crucial factor for maintaining the homeostasis of the gut microbiota and immune system, and consequently, the defense response against intestinal pathogenic bacteria, thereby elucidating a new role for water in the gut environment.
The results of this research were published online in the international academic journal iScience on May 16, 2024.
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