Aim Ulcerative colitis (UC) is an increasingly common condition particularly in developed countries.The lack of satisfactory treatment fuels the search for alternative therapeutic strategies.In the present study, we assessed the preclinical activity of berberine for the treatment of dextran sodium sulphate (DSS)induced chronic relapsing colitis in C57BL/6 mice.Methods Colitis of mice was induced by three cycles of 2.0% DSS.From day13 onward, colitis mice were orally administered with 20 mg/kg berberine for 30 days.The disease severity was determined by daily monitoring the body weight, stool consistency, and stool bleeding of mice.At the end of treatment, colons were collected and subjected to histological, RTqPCR, Western blot, and LCMS analyses.Lymphocytes were isolated from spleens and cultured for assessment of cytokine secretion.Results Berberine significantly ameliorated disease severity, colon shortening, histological injuries of colitis mice.Further, berberine treatment consistently and notably regulated DSSassociated increase in mRNAs levels of Th17related cytokines (inhibition of IL17 and RORγt) in the colon out of all tested cytokines.Moreover, the increases of TNFα, IL6 and IL23mRNA, and the phosphorylated STAT3 in colons of DSStreated mice were significantly reversed by berberine.In addition, berberine directly inhibited TNFα and IL17 secretion from cultured lymphocytes upon PMA/ionomycin restimulation.In the meanwhile, a sixtime amount of berberine in colon tissue (4.26 ± 2.62 ng · g1 colon)was measured when compared that in serum (0.76 ± 0.23 ng· ml1) and no detected histological changes was found in major organs of colitis mice.Conclusion We demonstrate for the first time that berberine exerts immunomodulatory effect in alleviating DSSinduced chronic relapsing colitis via inhibition of the JAK/STAT signalling activation in the inflamed colon.The demonstration of activity in this model supports the possibility of clinical efficacy of berberine in treating chronic UC.