T-2 Toxin Induced More Aggressively Cardiomyocytes Injury Through ER Stress In Selenium Deficiency Medium

Keshan disease,named after found in Keshan county in helongjiang province,is an endemic cardiomyopathy prevalent in China.The pathogenesis of Keshan disease now still is unclear,it is now commonly believed that the pathogenesis is large attributed to Se deficiency,T-2 toxin and myocarditis virus.But the relationship between this three factors is poorly described.T-2 toxin is a representative mycotoxin of type A trichothecene group produced by Fusarium fungi.T-2 toxin has been considered as a life-threatening mycotoxin,which is considered as one of the most dangerous food contamination sources.Previous studies have reported that T-2 toxin can induce injury of entire digestive tract and nervous system in human and animal,and results in rapid death due to internal hemorrhage.Selenium(Se)is an important trace element which is known as an indispensable micronutrient in normal development and metabolism,protect against oxidative stress-induced cell damage.Se deficiency can result in metabolism disordered and a substantial accumulation of free radicals in the body,which induce various diseases.Recent study found that selenium deficiency has the close relationship with cardiovascular disease.There is little report about the relationship between Se deficiency and the toxicity of T-2 toxin yet.In this paper,primary rat cardiomyocytes were cultured in serum free medium,then we study the influence of Se deficiency on toxic effect of T-2 toxin in cardiomyocytes and potential mechanism.The research contents were as follows:1.T-2 toxin induced more aggressively injury on cardiomyocytes in Se-deficiency medium.MTT assay and LDH release assay in T-2-treated cardiomyocytes were used to evaluate cell viability and injury.The result suggested that T-2 toxin could reduce the cell viability and induced cell injury,and with the concentration and time of T-2 toxin increasing,the toxic effect of T-2 toxin on cardiomyocytes increased.Different concentrations of Se-Met were pretreated in serum-free medium for 12h,then cells were exposure to T-2 toxin for 24h.The result suggested that the viability of cells cultured in medium contained 2μM Se-Met was stronger than other groups of cells,and LDH release was also lower than other groups(P<0.05).2.T-2 toxin could cause more severe oxidative stress in cardiomyocytes cultured in Se-deficiency medium.The different concentrations of T 2 toxin exposure to myocardial cells in the culture medium for 24h,myocardial cells were determined by SOD activity,and the content of GSH and MDA.Results showed that SOD activity and GSH contents decreased and discharge of MDA increased significantly with the increase of T-2 toxin concentration(P<0.05);0.25 μM T-2 toxins can cause the MDA content of myocardial cells significant increase(P<0.05).These results suggested that T-2 toxins can cause oxidative stress injury of myocardial cells,and with the increase of concentration of toxin,also will increase myocardial cell oxidative stress reaction.We pretreated cardiomyocytes with Se-Met at different concentrations for 12h,then added 0.25μM T-2 toxin in medium for 24h.Myocardial cells were determined by SOD activity,and the content of GSH and MDA.Results showed that,2μM Se-Met in cell culture medium could significantly prevent the decrease of SOD activity and GSH content and increase of MDA caused T-2 toxin(P<0.05).Thus we can get to the conclusion that T-2 toxin in Se-deficiency medium can cause more severe oxidative stress injury of myocardial cell.3.T-2 toxin induced more aggressively ER stress on cardiomyocytes cultured in Se-deficiency medium.Following incubation of cardiomyocytes with T-2 toxin,GRP78 mRNA,marker of ER stress,significantly increased after 3h(P<0.05)and decreased following the time as compared with control group.CHOP mRNA expression had also increased significantly after exposure to T-2 toxin for 6h(P<0.05)and increased following the time.And cells were treated with T-2 toxin at different concentrations(0,0.125,0.25,0.5μM)for 3h or 12h.GRP78 mRNA expression significantly increased at 0.25p,M T-2 toxin(P<0.05),but it decreased at 0.5μM T-2 toxin.CHOP mRNA expression also increased with the T-2 concentration increasing.To study the effect of selenium on T-2 toxin-induced ER stress in cardiomyocytes,we pretreated cardiomyocytes with Se-Met at different concentrations for 12h.And we examined the mRNA expression of GRP78 and CHOP after exposure to T-2 toxin for 3h and 12h,respectively.Compared with control group,T-2 toxin resulted in the cell expressed more GRP78 mRNA and CHOP mRNA in Se deficiency medium(0,1μM),however pretreated with sufficient Se-Met(2,4μM)markedly attenuated T-2 toixn-induced upregulation of GRP78 and CHOP mRNA.4.T-2 toxin induced cardiomyocytes injury in selenium deficiency medium through CHOP upregulation.To examine the role of CHOP in T-2 toxin-induced cell injury,si CHOP was used to suppress CHOP,si CHOP significantly inhibited T-2 induced CHOP expression(P<0.05).Whereas si CHOP and Se-Met together had no extra effect on CHOP expression induced by T-2 toxin,compared with si CHOP or Se-Met alone.si CHOP and pretreatment of Se-Met improved the cell survival(P<0.05).However,compared with si CHOP or Se-Met alone,si CHOP and Se-Met together had no significantly extra effect on cell injury induced by T-2 toxin.In conclusion,our study suggests that T-2 toxin can result in more aggressive injury on cardiomyocytes culture in Se-deficiency medium.T-2 toxin can induce more aggressively oxidative stress and ER stress in cardiomyocytes cultured in Se deficiency medium.And the physiologic concentration of selenium can alleviate the toxic effect of T-2 toxin,which is mediated by CHOP repression.Our study indicates the probable relationship between with T-2 toxin and selenium,providing an explaination for pathogenesis of Keshang diease.