The Preventive And Therapeutic Effects And Its Mechanisms Of Eurotium Cristatum On Ulcerative Colitis In Mice

Ulcerative colitis(UC)is a chronic inflammatory bowel disease(IBD)of unknown cause and immune abnormality.In recent years,with the improvement of living standards,the incidence of human and animals has been increasing year by year.At present,the treatment of UC is mainly drug therapy,but these drugs all have disadvantages and side effects to varying degrees,which urges people to actively explore new therapies for the prevention and treatment of UC.Eurotium cristatum(E.cristatum)is the dominant strain in the fermentation process of Fuzhuan tea,which can improve the flavor and quality of the tea leaves.Previous reports have shown that E.cristatum has a variety of medicinal values,including reducing obesity,regulating gut microbiota and reducing body inflammation,and so on.but whether E.cristatum can prevent and cure UC has not been reported.Our previous experiments showed that live E.cristatum,killed E.cristatum(KEC)and its main component polysaccharides(ECP)can prevent and control obesity by regulating gut microbiota.Therefore,in order to investigate the protective effect and mechanism of live E.cristatum,KEC and ECP on UC mice model induced by dextran sulfate sodium(DSS).We explored from the following aspects:Firstly,the protective effect of live E.cristatum on DSS-induced UC mice was studied in 8-week-old male C57BL/6J mice.Mice in each group were weighed and disease activity index(DAI)scores every day.Mice in each group were sacrificed 7days later and relevant samples were collected for subsequent analysis.The results showed that live E.cristatum could significantly improve colon shortening,body weight loss and increase of DAI score in UC mice,and significantly repair inflammatory cell infiltration and epithelial cell loss caused by DSS and other histopathological lesions.Further researches showed that live E.cristatum inhibit DSS induced the activation of the Nuclear factor kappa-B(NF-κB)and Mitogen-activated protein kinase(MAPK)signal pathway,reduce the expression of proinflammatory factor Tumor necrosis factor-α(TNF-α)and Interleukin-1β(IL-1β),at the same time improve the suppression of inflammation factor IL-10 in the expression of the colon,improve the UC mice intestinal inflammation.In addition,the results of immunohistochemistry showed that E.cristatum increased the expression of Tight junction(TJ)protein occludin in intestinal epithelial cells,and alleviated the damage caused by DSS to intestinal tract.These results suggest that E.cristatum,as a food added microorganism,has a protective effect on UC mice induced by DSS,which also provides a new therapeutic option for the prevention and treatment of UC in humans and animals.Secondly,in order to search for safer,more stable and effective components to prevent and control UC,we investigated the protective effects of KEC and ECP on UC mice.The results showed that both KEC and ECP significantly improved colon shortening,body weight loss and increase of DAI score in DSS-induced UC mice.The results of Western Blot and enzyme-linked immunosorbent assay(ELISA)showed that ECP and KEC could inhibit the activation of NF-κB and MAPK signaling pathways induced by DSS,reduce the expression of pro-inflammatory factor TNF-α,increase the expression of anti-inflammatory factor IL-10 in colon,and improve the intestinal inflammation of UC mice.The results of immunohistochemistry showed that KEC and ECP could increase the expression of TJ protein in colon and repair the intestinal damage caused by DSS.In addition,16 S r RNA sequencing results showed that both ECP and KEC reduced the richness of potentially harmful bacteria in UC mice at the species level,such as Escherichia coli,Enterococcus faecium,Clostridium perfringens,Bacteroides caccae,Rosia aeria and Prevotella melaninogenica,increasing the fringes of potentially beneficial bacteria,Alistipes finegoldii.Therefore,it can be preliminarily confirmed that ECP and KEC have prevention and control effects on UC mice,and can also regulate the structure and composition of gut microbiota in UC mice.Fecal microbiota transplantation(FMT)was conducted to further confirm the relationship between the treatment effect of KEC and ECP and changes in gut microbiota.The feces of donor mice treated with DSS,KEC and ECP were respectively transplanted to recipient mice treated with DSS.The body weight and DAI score of recipient mice were recorded every day.After 7 days of FMT,the mice were sacrificed and relevant samples were collected for subsequent analysis.The results showed that transplantation of feces from ECP and KEC treated donor mice significantly improved the severity of UC,repaired intestinal damage and intestinal barrier,and reduced inflammatory response in recipient mice compared with transplantation of feces from DSS treated donor mice.Therefore,our results indicate that the protective effect of KEC and ECP on DSS-induced UC mice is achieved by improving intestinal flora disturbance.In conclusion,all of live E.cristatum,KEC and ECP have protective effects on UC mice.The protective effect of KEC and ECP on UC mice by improving the anti-inflammatory effect mediated by gut microbiota disturbance,and ECP has a better preventive and therapeutic effects on UC mice.Therefore,our results suggest that live E.cristatum,KEC and ECP are expected to be potential drugs for the prevention and treatment of UC.