| In recent decades,the production of Pleurotus eryngii has surged and its economic benefits increased greatly.Pleurotus eryngii has attracted much attention as they are good sources of a high content of polysaccharide and moderate quantities of proteins with most essential amino acids,and polyphenols.Studies have found that functional components and their metabolites from P.eryngii could modulate the immune system and the intestinal microecological environment in the gastrointestinal tract and therefore lessen the inflammatory response,and play an important role in the inhibitory role of colitis and colon cancer.Although many research papers have identified a variety of functional active components in P.erygnii,the effect of P.eryngii on inflammatory bowel disease has not been reported.Still,it is not clear that the main functional ingredient in P.eryngii,which has inhibitory effect on colitis.In this study,an established chronic colitis mice model indued by oral dextran sulfate sodium(DSS)was established,to investigate the efficacy of P.eryngii in attenuating the inflammatory response.The following work has been performed and the results are summarized.(1)In this study,the protective effects of P.eryngii mushroom against inflammatory bowel disease(IBD)were determined in the DSS-induced colitis murine model.Dietary administration of 1%and 3%P.eryngii supplemented diet(w/w,in the diet)alleviated colonic inflammation induced by DSS,which was evidenced by decreased disease index,increased colon length,and reduced production of pro-inflammatory cytokines such as IL-1?,IL-2,and IL-6 in the colonic mucosa.P.eryngii diet also inhibited the expression of pro-inflammatory proteins,such as p-I?B,NF-?B p65,iNOS and TLR4.Sequencing the V3-V4 region of the 16S rRNA genes of gut microbiota demonstrated that DSS treatment significantly altered the microbiota composition,which correlated with exacerbated colonic inflammation in DSS-treated mice.Importantly,dietary treatment with P.eryngii partially reversed the alteration of fecal microbiota induced by DSS treatment.Furthermore,the levels of short-chain fatty acids in the cecum content were significantly increased by dietary P.eryngii.Overall,the anti-inflammatory and microbiota-modulating effects ofP.eryngii mushroom against colitis were demonstrated.(2)In total,5794 proteins were successfully identified by LC-ESI-MS/MS analysis of colonic tissue proteins in DSS-induced murine colitis model.Among them,there were 626 differentially expressed proteins between DSS group and Control group,of which 392 up-regulated proteins and 234 down-regulated proteins.There were 303 differentially expressed proteins between DSSPE group and DSS group,of which 107 up-regulated proteins and 196 down-regulated proteins.Differences in expression of DSSPE and DSS KEGG pathway are mainly:Steroid hormone,Arachidonic acid,Basal cell carcinoma,Linoleic acid metabolism,Phospholipase D signaling,Viral myocarditis,Chemical carcinogenesis,Natural killer cell mediated,Thyroid hormone signaling Twenty-five proteins were highly expressed in the DSS/Control group and low in the DSSPE/DSS group.21 proteins were low in the DSS/Control group and were highly expressed in the DSSPE/DSS group.And the results were verified by western blot,suggesting that the changes of these physiological processes may be involved in the pathogenesis of P.eryngii protein in relieving DSS-induced colitis and provide a suitable candidate target for the further study of the protective effect of P.eryngii on colitis.(3)In this chapter,a bioative protein,PEP,was isolated from P.erymgii,through(NH4)2504 precipitation and ion-exchange chromatograph.Proteomic analysis by matrix assisted laser desorption ionization-time of flight mass spectrometry showed that PEP was a novel protein with molecular xveight of 40 kDa.PEP exhibited anti-inflammatory effects in LPS-stimulated RAW264.7 macrophages by inhibiting the overproduction of pro-inflammatory mediators including nitric oxide,cytokine IL-1? and IL-6.It was further demonstrated that these anti-inflammatory effects of PEP were associated with the inhibition of inducible nitric oxide synthase expression,and the deactivation of nuclear factor-kappa B and mitogen-actived protein kinase pathways.PEP might be a good candidate for anti-inflammation in the gastrointestinal tract,especially in the colon.(4)Our previous chapters demonstrated the identity of a novel protein from P.eryngii,namely PEP,and its anti-inflammatory activities.Herein,we further determined the inhibitory effects of PEP against colon cancer cells.We found that PEP suppressed cell proliferation of human and murine colon cancer HCT116 and MC38 cells in a dose and time-dependent fashion,while it showed no inhibitory effect on normal human colonic myofibroblasts CCD-18Co at the same concentrations tested.Moreover,PEP induced cell cylce arrest and led to extensive cellular apoptosis in colon cancer cells,which was associated with downregulation of cell cycle-related signaling proteins,e.g.cyclin B,cyclin E and cdc-2,and upregulation of apoptosis-related signaling proteins,e.g.p53 and c-PARP.Results from in vivo study showed that PEP treatment significantly suppressed tumor development of allografted colon cancer cells in mice,and this inhibition was associated with upregulation of p21,p53,caspase-3 and cleaved caspase-3.Overall,our results provided a basis for PEP as a promising preventive agent against colon cancer. |
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