Protective Effect And Mechanism Of Polysaccharide From Natural Cordyceps Sinensis On Intestinal Health

Cordyceps sinensis(C.sinensis)(Berk.)Sace.,the precious Chinese traditional medicine,is regarded as one of the three traditional tonics along with Ginseng and Pilose antler.It contains a variety of bioactive ingredients,including polysaccharides,cordycepic acid,nucleosides and so on.Polysaccharide is one of the major consitituents in C.sinensis which possessed a wide range of bioactivities.In our previous study,its chemical structure has been characterized in detail.Further in vitro study concerning the effect of water extracted polysaccharide on RAW 264.7 indicated that its potent immunomodulatory activity.Therefore,in this study,using cyclophosphamide(Cy)induced intestinal injury model and dextran sulfate sodium(DSS)induced colitis model,its alleviating effect on intestinal injury was investigated,further to explore its possible mechanisms in terms of intestinal immunity and gut microbiota.The main results are summarized as follow:1.The intestinal injury mouse model,established through intraperitoneal injection of Cy,was used to explore the alleviated effect of different doses of polysaccharide from natural C.sinensis(NCSP)on intestinal injury as well as the influence of intestinal immunity and gut microbiota in mice with intestinal injury.The results showed that NCSP increased the thymus index and liver antioxidant capacity of intestinal injury mice with dose-dependent manner,promoted the levels of goblet cells and mucus in small intestine;Additionally,NCSP increased the numbers of CD4~+T cells and Ig A-secretory cells,enhanced the differentiation of T helper(Th)1,Th2,Th17 and regulatory T(Treg)cells,and regulated the equilibrium of Th1/Th2,Th17/Treg cells.Furthermore,NCSP modulated the structure of gut microbiota,promoted the growth of Muribaculaceae,one kind of beneficial bacteria,and increased the levels of total short chain fatty acids(SCFAs)and acetic acid in feces of mice.2.The alleviated effect of water-extracted polysaccharide from natural C.sinensis on colitis mice,induced by DSS,was evaluted.The results demonstrated that water-extracted polysaccharide from natural C.sinensis could increase colon length,attenuate pathological injury,improve antioxidant capacity,regulate the expression levels of cytokines and tight junction(Occludin and Claudin-1)as well as modulate the structure of intestinal microbiota and increase the concentration of SCFAs in cecal content.Furthermore,polysaccharide inhibited the expression of key protein in nuclear transcription factor-kappa B cells(NF-κB)pathway.The attenuate effect of a more purified polysaccharide fraction isolated from NCSP(NCSP-50)on colitis mice was better than that of NCSP.3.The possible mechanism of NCSP-50 promoting secretory immunoglobulin A(s Ig A)content concerning about B cells transformation and the procedure of s Ig A secretion in colitis mice was studied.The results showed that NCSP-50 significantly reduced the levels of immune cells,including macrophages,dendritic cells(DCs)and CD4~+T cells in colon.It regulated differentiation of CD4~+T cells by promoting polarization of Th2and Treg cells,while inhibiting the differentiation of Th1 and Th17 cell,which indicated that NCSP promoted the B cell transformation in T cell-dependent manner.In T cells independent pathway,NCSP-50 inhibited the expression of a proliferation-inducing ligand(APRIL),but prompted the expression of vasoactive intestinal peptide receptor(VAPC)2.NCSP-50 suppressed the expression of retinal dehydrogenase(RALDH)-1,while increased the expression of RALDH-2.NCSP-50 increased the levels of activation-induced cytidine deaminase(AID),a key factor during B cells transformation.Additionally,NCSP-50 obviously enhanced the levels of immunoglobulin A(Ig A)and p Ig R,then improved the secretion of s Ig A.These results implied that NCSP-50 mainly promoted B cell transformation to Ig A secretory cells in T cells dependent manner,increased the levels of Ig A and polymeric immunoglobulin receptor(p Ig R),then enhanced the secretion of s Ig A in colon.4.Fecal microbiota transplantation(FMT)was performed to study the role of gut microbiota in NCSP-50 alleviating colitis.These colitis mice were randomly divided into model control(MC)group,donor groups and receptor groups of fecal bacteria.Indexes associated with colitis in each group were compared.The results found that high dose of NCSP-50(NCSP-50H)group and receptor group of fecal bacteria from NCSP-50H increased the colon length,reduced the expression of inflammatory cytokines in comparison to that in MC group.At the same time,it suppressed the m RNA expression levels of NF-κB and increased the contents of s Ig A.5.It was examined the attenuate effect of NCSP-50 on colitis mice,whose gut microbiota destructed by antibiotic treatment.The colitis mice were randomly assigned to MC group,NCSP-50H group,Antibiotic+MC(simultaneously administrated with normal saline and broad-spectrum antibiotics)group,Antibiotic+NCSP-50(simultaneously administrated with NCSP-50 and broad-spectrum antibiotics)group.The data showed that compared with NCSP-50H group,mice administrated with NCSP-50 and antibiotics simultaneously showed colon shorten,augment of relative levels of m RNA expression of inflammatory cytokines,increase TLR-4 and NF-κB expression levels and reduction of s Ig A content.Besides,there was no significant difference between mice in MC and Antibiotics+NCSP-50 groups.In conclusion,the above results indicated that water-extracted polysaccharide from natural C.sinensis relieved intestinal injury via modulating the gut microbiota and intestinal immunity,thus maintaing intestinal health.