This study aims to reveal the gut microbiota and immune changes associated with the anti-CD20 therapy in patients with multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system (CNS) that is usually diagnosed in young adults. The untreated course leads to severe disability within 15 years. The loss of myelin caused by the inflammation and axonal damage leads to atrophy of the CNS. MS is triggered by a combination of factors, with the genetic component accounting for less than a third of the risk. Other aspects such as hypovitaminosis D, previous EBV infections, smoking and obesity have been identified as possible risk factors. In recent years, a link between the microbiota and immune system has been discovered and identified as an important pathogenic factor in autoimmune diseases outside the gut.In this study we are investigating the changes in the gut microbiota in MS patients undergoing and receiving anti-CD20 therapy (ocrelizumab). We relate the effect of B-cell depletion to antimicrobial antibody response and markers of intestinal barrier integrity and virome profile in serum samples.