The Change Of Extracellular Heat Shock Protein70in Intestinal Mucosa And Its Effects On Intestinal T-cell Immune Function In Severely Burned Rats

Objective: To investigate the effect of extracellular heat shock protein70(eHSP70) on intestinal T cell immunity by observing the changes of eHSP70and IL-2expressions in the intestinal mucosa of severely burned rats and using HSP70(eHSP70) in vitro to stimulate CD3+T cells separated from intestinal lymph of burnedrats.Methods: Sixty SD male rats were randomly divided into normal control group(n=10)and burn model groups(n=50).Rats were burned with vapor under3MPapressure and107℃temperature for twelve seconds to achieve III degreescalding,and a30%total body surface area(TBSA) burn model was made. Rats weresacrificed before(normal control group) and after3,6,12,24,48burn hour (PBHgroups). SD rats were killed by cervical dislocation to extract the intestinal mucosa ateach time point. The enzyme linked immunosorbent assay(ELISA) was used to detecteHSP70and IL-2expressions of intestinal mucosa in each group. Flow cytometrytechniques were used for the separating of the CD3+T cell in intestinal lymph nodes.Isolated cells were randomly divided into blank control group, low concentrationgroup (5μg/ml eHSP70), medium concentration group(10μg/ml eHSP70) and highconcentration group(20μg/ml eHSP70). Flow cytometry was used to detect theproportion of Th1/Th2cells and CD3+T cell apoptosis rate. ELISA method was usedfor detection of IL-2and IL-10levels in the culture supernatant.Results:(1) Compared with the normal control group(1278±135.4), The expression ofeHSP70in intestinal mucosa had decreased at3h (538±40.4)after severe burn, peakedat12h(314±20.5)，About1/4of normal control group. The difference was statisticallysignificant (P<0.05).(2) The level of IL-2expression of3PBH,6PBH,12PBH,24PBH and48PBHgroup rats were38.6±2.25,32.3±1.03,25.3±3.58,33.9±4.12,44.3±2.62,which wassignificantly reduce compared with that of normal control group (48.6±4.89)(P<0.05). (3) The expression of IL-2was positively correlated with extracellular HSP70expression in the intestinal mucosa of severely burned rats(r=0.920, P <0.01).(4) Th1cell ratio were significantly increased and Th2cell ratio weresignificantly decreased in eHSP70stimulation group compared to blank control group(P <0.05).(5) The apoptosis rate of CD3+T cells were significantly decreased in eHSP70stimulation groups compared to blank control group,The rate of medium concent-ration group was lowest(P <0.05).(6) Compared with the blank control group, The expression of IL-2wassignificantly increased in eHSP70stimulation groups. The lever of increase was mostobvious in the final concentration of10μg/ml medium concentration group(P<0.05).No significant differences were found among the blank control group and eHSP70stimulation groups about the level of IL-10expression(P>0.05).Conclusion: The expression of the extracellular heat shock protein70in theintestinal mucosa in severely burned rats was decreased compared to that in normalcontrol group, The changes may be responsible for the intestinal immune response.The suitable concentration of eHSP70can decrease the apoptosis rate of T cells,enhance T cell activity, promote T cell differentiation from Th0to Th1and promotethe release of IL-2. Can be used as a new target for correcting or reversing immunefunction of inhibition after burn.