Protective Effect And Mechanism Of Polysaccharide From Ganoderma Atrum On Acrolein-induced Macrophage Damage

As a kind of valuable drug dual-use fungus,Ganoderma atrum used in eastern countries already has more than 2000 years.In our laboratory,a kind of polysaccharide named PSG-1 was isolated and purified from Ganoderma atrum,the antitumor,anti-oxidant,and anti-cardiovascular functions of PSG-1 have been deeply studied in the previous stage.This study used cyclophosphamide(CY)induced a mouse model of immunosuppression,and explored the protective effect of PSG-1 on cyclophosphamide-induced intestinal barrier damage in mice based on autophagy pathway.Acrolein(ACR)was also used to establish a macrophage injury model,the protective effects of PSG-1 on macrophages were explored from the perspectives of oxidative stress,apoptosis and autophagy.The main conclusions of this study are summarized as follows:1.The level of normal autophagy in immunosuppressed mice induced by CY is suppressed,and the expression levels of tight junction proteins zo-1,claudin-1,and occludin in the small intestine are also reduced,thereby destroyed the intestinal mucosal integrity and causing intestinal immune dysfunction,PSG-1 restored normal autophagy levels in mice and increases the expression of tight junction protein in the small intestine tissue,thereby repaired the mouse intestinal mucosal barrier.2.ACR-induced macrophage damage model will damage cell viability,SOD viability and CAT viability will be inhibited,MDA production was increased,increased the expression of Keapl,a key protein in the Nrf2/Keapl pathway,and reduces the expression of Nrf2,and the oxidation/anti-oxidation balance in macrophages will be destroyed.PSG-1 could restore cell viability,increase the vitality of SOD and CAT,and reduce the content of MDA,reduce the expression of Keapl,increase the expression of Nrf2,thereby protecting cells from oxidative stress damage.3.In ACR-induced macrophage damage model,ROS content increased,mitochondrial transmembrane potential was destroyed,MMP decreased,the expression of apoptosis inhibited protein Bcl-2 decreased,the expression of positive apoptosis-related proteins CytC,caspase-3 and caspase-9 increased,thereby induced apoptosis of mitochondrial pathway:in macrophages.Treatment with PSG-1 reduced ROS content in macrophages under the action of acrolein,increased MMP,reduced the protein expressions level of CytC,caspase-3 and caspase-9,increased the expression level of Bcl-2,thereby preventing macrophages from undergoing mitochondrial apoptosis.4.ACR treated macrophages reduced the expression the level of p-m-TOR,the key protein of m-TOR pathway,and increased the expression levels of autophagy proteins LC3,Beclin-1,Atg5,and Atg7,resulting excessive autophagy of macrophages,PSG-1 treatment of cells increased the expression level of p-m-TOR and reduce the expression level of key autophagy proteins,thereby protecting macrophages from damage caused by excessive autophagy.Autophagy inhibitors inhibited the expression of CytC,the key protein in the apoptotic pathway,indicating that PSG-1 may protect macrophages under the action of ACR through an autophagy-dependent apoptosis pathway.