title: Crohn's disease: the hot hypothesis.
abstract: The peculiar geographic distribution of inflammatory bowel disease is a puzzle for researchers. A low vitamin D status has now been linked to several Th1-mediated autoimmune diseases, including multiple sclerosis, type 1 diabetes and rheumatoid arthritis, with the strongest evidence for the vitamin's protective role in multiple sclerosis. Sunlight and vitamin D may be potent immunomodulatory agents by down-regulating Th1-driven immune responses and inducing the synthesis of antimicrobial peptides considered as natural antibiotics of the immune system. Similarly to multiple sclerosis, we propose in CD the so-called north-south gradient may be partly explained by variations in the degree of sun exposure, with vitamin D being a "seasonal stimulus". These observations may yield a better understanding of the pathophysiology of Crohn's disease and pave the way for developing new therapeutic approaches for an incurable disease. Whether a low vitamin D status is associated with an increased risk of Crohn's disease in the general population and whether vitamin D and heliotherapy may be effective in treating Crohn's disease will require additional investigations.
authors.affiliation: Inserm, U724, and Department of Hepato-Gastroenterology, University Hospital of Nancy, Allée du Morvan, 54511 Vandoeuvre-lès-Nancy, France. peyrin-biroulet@netcourrier.com
authors.forename: Laurent
authors.initials: L
authors.lastname: Peyrin-Biroulet
authors.forename: Abderrahim
authors.initials: A
authors.lastname: Oussalah
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Bigard
mesh_terms: D000818:Animals; D003424:Crohn Disease / Q000209:etiology* / Q000276:immunology*; D006801:Humans; D018448:Models, Immunological; D014807:Vitamin D / Q000276:immunology*; D014808:Vitamin D Deficiency / Q000150:complications* / Q000276:immunology*
chemical_list: D014807:Vitamin D