Editorial: dietary interventions to understand and treat primary sclerosing cholangitis—is gluten‐free diet a starting point?

Little is known about dietary factors in primary sclerosing cholangitis (PSC), except from cross- sectional observations of reduced consumption of coffee and fish. 1– 3 Genetic studies suggest that environmental factors are important. 4 The strong link between inflammation of both gut and liver points to the gut microbiome and interactions with dietary exposures as a potential player. In a pilot study of gluten- free diet (GFD), Liwinski and Hübener et al have made a first attempt to describe the molecular effects of a dietary intervention in PSC. 5 In the study, 15 individuals with PSC- IBD completed 8 weeks of GFD, aiming to test the impact on colonic inflammation (sigmoidos-copy) and liver stiffness. An association between coeliac disease and PSC is well known. 6 In this study, individuals diagnosed with coeliac disease were specifically excluded, as the aim was to investigate the non- coeliac effects of gluten and the associated wheat proteins amylase trypsin inhibitors (ATIs). No effect was observed on primary or clinical endpoints, suggest-ing that as of now, GFD is not a relevant intervention in PSC without coeliac disease. However, the observations at molecular level were of interest. In mucosal biopsies, transcription of the cytokines CCL- 2, IL-6, IL- 8 and IL- 10 were reduced after GFD. In the circulation, the cor-responding cytokine levels were unchanged, but the levels of fibrosis markers thrombospondin- 2 and thrombinspondin- 4 were reduced, while pro- C3 was unchanged. Microbial changes were limited, but 10 microbial species were differentially abundant before and after