Effect Of SAM On Methylation Status Of Perforin Gene Promoter In CD4~+T Cells Of Autoimmune Emphysema Rats And Alveolar Septal Cell Apoptosis

Objective:To investigate the effects of SAM on methylation status of perforin gene promoter in CD4~+T cells of autoimmune emphysema rats and alveolar septal cell apoptosis.Our study is aimed at providing a theoretical basis of chronic obstructive pulmonary disease(COPD)pathogenesis and it’s treatment.Methods:Thirty-two rats were randomly divided into four groups:normal control group(n=8),model group(n=8),methylprednisolonegroup(n=8)and SAM intervention group(S-adenosylmethionine,n=8).Intraperitoneal injection of primary cultured human umbilical vein endothelial cells was given to establish the autoimmune emphysema models,the SAM group was injected with SAM(200mg/kg.d)in intraperitoneally for intervention at the meantime,the methylprednisolonegroup was injected with methylprednisolone(10mg/kg.d)in intraperitoneally for intervention at the meantime,the normal control group was received intraperitoneal injection of adjuvant only and equal volume normal saline with daily.After 21days,pathological changes were observed in lung tissues stained by hematoxylin eosin,mean liner intercept(MLI)and mean alveolar number(MAN)weres measured.The levels of AECA in serumwas detected by ELISA.Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL)technique was used to detect the alveolar septal cells apoptosis.CD4~+T lymphocytes were taken from spleens and DNA extracted.Perforin gene promotor methylation was investigated in CD4~+T cells by using the second-generation sequencing method after bisulfate conversion.Results:The MLI of the model group,SAM group and the methylprednisolone group has higher changed than the normal group,the MAN was decreased.The MLI of the SAM groupand the methylprednisolone group has decreased changed than the model group,the MAN was higher.The MLI of the methylprednisolone group was higher than that of the SAMgroup,the MAN was less.The aboveP<0.05.(2)The AECA of the model group,SAM group and the methylprednisolone group has higher changed than the normal group.The AECA of the SAM groupand the methylprednisolone group has decreased changed than the model group.The AECA of the methylprednisolone group was higher than that of the SAMgroup.The aboveP<0.05.(3)The apoptosis index(AI)of alveolar septal cells in the model group,the SAM group and the methylprednisolone group has higher changed than the normal group.The AI in the SAM groupand the methylprednisolone group has decreased changed than the model group.The AI in the methylprednisolone group was higher than that of the SAMgroup.The aboveP<0.05.(4)The mean methylation level of the model groupand the methylprednisolone group has less changed than the normal group(P<0.05).The mean methylation level of the model groupand the methylprednisolone group has less changed than the SAM group(P<0.05).There was no significant difference between the model group and the methylprednisolone group,the SAM group and normal group(P>0.05).Conclusions:(1)The promoter region of CD4~+T lymphocyte perforin gene in rats with autoimmune emphysema is hypomethylated,which may induce the generation of AECA and increase the apoptosis of alveolar septal cells,and jointly participate in the formation of autoimmune emphysema in rats.(2)S-adenosylmethionine prevents the development of autoimmune emphysema of rats,and the effect is better than that of methylprednisolone.The mechanism may be related to SAM improving the hypomethylation state of perforin gene promoter,reducing the production of AECA and inhibiting the apoptosis of alveolar septal cells.