Effect Of Polysaccharide From Ganoderma Atrum On Intestinal Mucosal Immunity And Mucosal Injury In Mice

Ganoderma atrum has been used for more than 2000 years in our country.Modern medicine also proveed that Ganoderma atrum has many functions such as enhancing immunity,inhibiting tumor growth,reducing blood pressure,high blood lipids,high blood sugarand anti-oxidation.Polysaccharides were considered to be the main bioactive components.In our laboratory,Ganoderma atrum cultivated in the Ganzhou of Jiangxi Province was used as raw material to separate and purify polysaccharide PSG-1.In the early stage,the immunoregulatory effects of PSG-1 on macrophages and spleen lymphocytes have been thoroughly investigated.In this study,an immunosuppressive model was was established by intraperitoneal injection of cyclophosphamide,and molecular biological methods were used to study the effects of different doses of PSG-1 on intestinal mucosa barrier and intestinal mucosa in mice at the tissue level,cells level and protein level.The main conclusions of this study are summarized as follows:1.Intraperitoneal injection of cyclophosphamide resulted in decreased the body weight,thymus atrophy,and the injury of intestinal mucosal barrier,which also affected the digestion and absorption of nutrients by mice.PSG-1 can make the immunosuppressived mice restore weight and increase the thymus index,which is beneficial to the recovery of the body's health.At the same time,PSG-1 can increase villi length,crypt depth,and make V/C ratio increase significantly.What's more,PSG-1 can also promote the differentiation and proliferation of stem cells at the bottom of the crypt into small intestine goblet cells and increase the secretion of mucus on the intestinal villi.It can be seen that PSG-1 can repair small intestinal mucosal barrier injury in a level.2.PSG-1 can promote the recovery to normal levels of cytokines INF-?and IL-1?in the small intestine of immunosuppressived mice,increase the release of immunoglobulin IgG,IgE,IgM in intestinal tissues and SIgA,IgE in serum.And then participate in the regulating of body's humoral immune system.In addition,PSG-1can also promote the relative expression of IL-2 and TNF-?at mRNA levels in the small intestinal.The study shows that cyclophosphamide has a destructive effect on the intestinal immune environment in normal mice.PSG-1 can participate in the regulation of the intestinal immune environment.3.PSG-1 can promote the expression of Toll-like receptor(TLR-2,TLR-4,TLR-6)on the surface of intestinal epithelial cells,and improve the intestinal T cell differentiated to different cell subsets:CD4~+T,CD8~+T cells,and it has a greater effect on CD4~+T cells,increasing CD4~+T/CD8~+T ratio.ELISA was used to detect different types of cytokines secreted by Th1,Th2,Th17 and Treg cells in the small intestine.Wstern blot was used to detect the expression of nuclear transcription factor protein in the small intestine.It was found that PSG-1 can regulate the secretion of cytokines in different subsets of T cells(Th1,Th2,Th17,and Treg)in the small intestine,and regulate the expression of key proteins(T-bet,GATA-3,ROR?t,and Foxp3),which may promote the recovery of Th1/Th2 cell balance and the balance of Th17/Treg cells.Finally,direct immunofluorescence assay showed that PSG-1 can promote the expression of IgA-secreting cells in the small intestine and it can enhance the secretion of the main effector factor SIgA.The results showed that the possible pathways of PSG-1 promoting intestinal cell differentiation were:immune cell surface receptor TLRs recognized the stimulation of PSG-1,then promoted T cells differentiation into CD4~+T,CD8~+T cells,and naive CD4~+T cells are mainly differentiated into Th1,Th2,Th17 and Treg cell subsets under the stimulation of cytokines.Th2 cell-mediated humoral immune activation of B cells,and promoted the proliferation of IgA plasma cells,mature IgA plasma cells secrete SIg A antibodies in the intestinal participate in mucosal immunity.