| Ganoderma atrum(G.atrum)is a traditional and valuable medicinal herb in China and it is a medicinal and dietary fungus.As one of the important active substances in G.atrum,G.atrum polysaccharide(PSG-1)has been proved to have various biological activities,but little research has been reported on the regulatory effect of PSG-1 on intestinal inflammation and its mechanism.In this study,we investigated the protective effect of PSG-1 against intestinal inflammatory damage.By establishing a mouse model of DSS-induced ulcerative colitis in vivo,we explored the effects of PSG-1 intervention on the phenotypic indicators,the physical barrier related to autophagy apoptosis and the immune barrier related to DCs in mice,In addition,the LPS-induced inflammatory injury model of intestinal epithelial IEC-6cells was constructed by RNA seq in vitro.The genes associated with the protective effect of PSG-1 were comprehensively screened and searched for by RNA sequencing technology,as well as the selected key pathways were further demonstrated at the translated level.The main findings obtained in this study are as listed below:1.DSS-induced mice with acute ulcerative colitis showed significant changes in apparent indices,including sudden weight loss,blood in stool and diarrhea,while PSG-1 intervention effectively reduced their DAI indices and alleviated the weight gain and shortening of the mouse colon.The analysis of the section results showed that the colitis caused by DSS severely damaged the intestinal structure of the mouse colon,while PSG-1 could effectively protect the integrity of the intestinal structure and improve the secretion of goblet cells in the colon,and protected the integrity of the mouse colon.2.PSG-1 ameliorated the abnormal secretion level of inflammatory factors in the colonic tissues,which effectively reduced the level of inflammation in mice,and the PSG-1 intervention upregulated the intestinal tight junction(TJ)protein content in mice with DSS-induced colitis as well as restored the expression of occludin,claudin-1 and Zo-1 proteins inhibited by DSS.Morever,further studies revealed that abnormal activation in colonic tissues of colitis mice and DCs were significantly inhibited in PSG-1 group,and the secretion of IL-10 in DCs was further increased,which indicated that the DCs-associated intestinal immune barrier was repaired.3.Abnormal apoptosis of intestinal epithelial cells may mediate or exacerbate the destruction of colonic intestinal structure,and PSG-1 intervention could effectively inhibit excessive apoptosis of colon in DSS-induced colitis mice.Morever,PSG-1 could further upregulate the content of colonic autophagy-related protein in DSS-induced colitis mice,which was confirmed in western-blot experiments,and further experimental results indicated that this apoptosis/autophagy regulation may be related to the degree of activation of Akt/m TOR pathway in mice.4.LPS has a lethal effect on IEC-6 cells,and PSG-1 intervention reduced the level of IEC-6 cell death caused by LPS while promoting the secretion of cellular TJ proteins.RNA sequencing results showed that the number of genes up-regulated and down-regulated in the LPS group treatment was 806 and 142 compared to normal cells,while the number of genes up-regulated and down-regulated in the PSG-1intervention group compared to the LPS treatment group was 152 and 211,respectively.Double GO analysis and KEGG analysis indicated that PSG-1intervention may exert a protective effect by increasing the migration ability of cells and reducing the level of apoptosis. |
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