Mechanism Of ROS-NF-?B Pathway In Intestinal Epithelial Cell Apoptosis Induced By Heat Shock Combined With LPS

BACKGROUND AND AIMSHeatstroke(HS)is a life-threatening disease characterized by an increase in core body temperature of more than 40? after exposure to high temperatures or strenuous exercise.In severe cases,multiple organ dysfunction syndrome(MODS)may even occur,with high mortality and poor prognosis.Intestinal endotoxemia secondary to heat stroke is a common cause of MODS in heat stroke patients.At present,the specific mechanism of intestinal barrier injury in heatstroke is still not completely clear,so in-depth study of its pathogenesis and treatment is an important direction urgently needed to be discussed.Heat shock leads to the distribution of blood to the cutaneous,and the production of Reactive oxygen species(ROS),which leads to the intestinal epithelial apoptosis and bacterial flora migration after heat stroke.LPS stimulation has been shown to increase ROS and activate NF-?B transcriptional activity.In addition,the activation of mitogen-activated protein kinase(MAPK)and activator protein-1(AP-1)is involved in the regulation of cell apoptosis,and their upstream transcriptional regulator is NF-?B.In combination with a review of the literature,we hypothesized that increased intestinal epithelial permeability and LPS stimulation after heat stroke may lead to a further increase in ROS and promote prolonged activation time of MAPK and c-jun induced by NF-?B,thereby further increasing intestinal epithelial cell apoptosis.To elucidate the specific mechanism of intestinal cell apoptosis caused by LPS combined with heat stroke,lay a foundation for further explaining the damage of multiple organs of the whole body caused by heat stroke,and provide theoretical basis for the diagnosis,treatment and prevention of heat stroke.METHODEstablished the mouse model of severe heat stroke and the cell model of heat stroke combined with LPS.ELISA,pathological staining,immunohistochemistry,dcfh-da fluorescent probe,flow cytometry,western blotting,siRNA and adenovirus overexpression of NF-?B p65 were used to investigate the specific mechanism of apoptosis induced by ROS activation of NF-?B pathway in intestinal epithelial cells stimulated by heat shock combined with LPS.RESULT1.Intestinal epithelial cells of mice with severe heat stroke were significantly apoptotic,accompanied by increased circulating LPS.Nuclear translocation of NF-?B p65 in intestinal epithelial cells activates the MAPKs and ap-1 pathways.2.ROS levels in intestinal epithelial cells increased and apoptosis increased after heat shock combined with LPS stimulation.Cell permeability increased first and then decreased with the recovery time.3.ROS accumulation causes nuclear translocation of NF-?B p65 in intestinal epithelial cells,leading to cell apoptosis.4.Heat shock combined with LPS stimulation can cause activation of MAPKs and AP-1 pathways in intestinal epithelial cells,and inhibition of MAPKs and AP-1 activation can alleviate apoptosis.Moreover,the phosphorylation of MAPKs and AP-1 increased with the strike time and decreased with the recovery time.5.Bioinformatics predicted the presence of binding sites of NF-?B p65 in the c-jun promoter region.Down-regulation of NF-?B p65 inhibited MAPK and c-jun activation,while up-regulation of NF-?B p65 promoted MAPK and c-jun activation.CONCLUSION1.The increase of ROS in the intestinal epithelial cells of mice with severe heat stroke leads to cell apoptosis and increased intestinal permeability,which leads to the circulation of LPS and causes endotoxemia,and the early recovery injury after heat stroke continues to worsen.2.Heat shock combined with LPS stimulation can cause ROS increase in intestinal epithelial cells,and activate NF-?B p65 into the nucleus to play its transcriptional activity and promote apoptosis,thus further increasing intestinal permeability in the early recovery stage of heat stroke.3.After heat shock combined with LPS stimulation,NF-?B p65 in the convalescent intestinal epithelial cells can activate the MAPK and ap-1 pathways to promote apoptosis.