Probiotics in Patients With Primary Sclerosing Cholangitis and Inflammatory Bowel Disease- a Randomized Placebo-Controlled Cross-Over Trial

I. INTRODUCTION Primary sclerosing cholangitis (PSC) is a progressive cholestatic liver disease characterized by multifocal strictures of intrahepatic and extrahepatic bile ducts, which frequently leads to biliary cirrhosis and liver failure. The aetiology of PSC is unknown but is thought to be (auto)immune-mediated. Nevertheless, in a number of randomized controlled trials a clear benefit of treatment with various immunosuppressive agents, such as D-penicillamine, methotrexate, corticosteroids or nicotine, could not be demonstrated. Although treatment with ursodeoxycholic acid (UDCA) improves serum liver tests and is prescribed on a large scale for PSC patients, this therapeutic modality may have no beneficial effect on the course of the disease.

70 - 90% of patients with PSC have concurrent inflammatory bowel disease (IBD), mostly ulcerative colitis. Conversely, 7% of patients with IBD have PSC. The close association between inflammatory bowel disease and PSC suggests that substances originating from the inflamed gut may damage the liver and biliary tree. Bacterial products may act as toxic proinflammatory agents. N-formyl L-methionine L-leucine L-tyrosine is a peptide produced by enteric flora. When this peptide was introduced into the colon of rats with colitis, it was absorbed, underwent enterohepatic circulation, and appeared undegraded in bile. Histologic changes in the livers of the rats resembled those in PSC.

Probiotics are beneficial bacteria that are used to redress the bacterial composition of the enteric flora which may be altered in disease. Beneficial effects of probiotics have already been described in diseases such as inflammatory bowel disease, pouchitis and non-alcoholic fatty liver disease. Probiotic bacteria have also been shown to counteract inflammatory processes by enhancing the degradation of enteral antigens, reducing the secretion of inflammatory mediators, thereby modifying in a beneficial way the balance between pro- and anti-inflammatory mediators, and stabilizing gut barrier functions. These effects may benefit PSC patients.

Our hypothesis is that administration of probiotics may improve the composition of the enteric flora and subsequently decrease the release of substances that may be toxic and harmful for the liver and biliary tree in PSC patients. Furthermore, immunological alterations induced by treatment with probiotics may have positive effects in PSC.

II. AIM OF THE STUDY Primary aim: assessment of the effects of treatment with probiotics on serum liver tests.