November 6, 2018
Keio University School of Medicine
A research group from the Department of Gastroenterology and Hepatology, Keio University School of Medicine, led by Professor Takanori Kanai, Project Lecturer Tomohisa Sujino, and Assistant Professor Yuki Kiyohara, has for the first time revealed through experiments in mice the existence of a "skin-gut axis," in which the onset of psoriasis alters the gut microbiota (Note 1), creating an intestinal environment that makes enteritis more likely to worsen.
Psoriasis (Note 2) and inflammatory bowel disease (Note 3) are types of autoimmune diseases characterized by chronic inflammation of the skin and gastrointestinal tract, respectively. The number of patients with both diseases is on the rise in Japan. Although these two diseases differ in the organs they affect and their underlying mechanisms, it is known that suffering from one increases the risk of developing the other. However, the reason for this frequent comorbidity has remained unclear. Furthermore, while it is known that the composition of the gut microbiota in patients with psoriasis and inflammatory bowel disease differs from that of healthy individuals, with some similarities between the two conditions, it was not understood how inflammation in the skin and the gastrointestinal tract mutually affect each other.
Using mouse models of psoriasis and enteritis, our research group investigated the environmental changes that the onset of psoriasis brings to the gastrointestinal tract and how these changes in the gastrointestinal environment affect the onset of enteritis. This study revealed that the onset of psoriasis causes changes in the composition and function of immune cells in the colonic mucosa, in addition to altering the composition of gut bacteria. Furthermore, we demonstrated that such changes in the intestinal environment exacerbate colitis and, in particular, that alterations in the gut microbiota are essential for this exacerbation.
This study has, for the first time, elucidated the underlying mechanism for why patients with psoriasis are prone to comorbid inflammatory bowel disease and why common changes in the gut microbiota are observed in these diseases. This was explained through the concept of a "skin-gut axis," whereby the presence of dermatitis creates an intestinal environment susceptible to inflammation. It is hoped that this research, following future clinical studies, will lead to the development of new therapeutic strategies to prevent the onset and progression of inflammatory bowel disease in patients with psoriasis.
The results of this research were published on September 24, 2018 (U.S. Eastern Time), in the American Gastroenterological Association's journal, "Cellular and Molecular Gastroenterology and Hepatology."
For the full press release, please see below.