| Background:Heat illness is an acute heat-induced disease in hot and humid environment. Heat stroke is a type of disease as a result of exposure to hot and humid environment, and lead to body core temperature rise rapidly (>40℃), accompanied by skin burning, anidrosis, disturbance of consciousness (such as delirium, convulsions, coma) and multiple organs or systems failure, which is the severest type of heat illness, whose mortality is as high as 50%. Heat stroke is clinically divided into the classic heat stroke (CHS) and exertional heat stroke (EHS). The clinical manifestations and physiopathologic mechanisms of heat stroke is similar to sepsis, but its inflammatory response is more severe. In pathogenic mechanisms of sepsis, systemic inflammatory response syndrome and compensatory anti-inflammatory response syndrome occur almost at the same time, a variety of cytokines were produced, which can cause immune paralysis and severe systemic infection, eventually contributed to patients’death. Regulatory T Cells were one of the key Cells involved, multiple studies confirmed that the proportion of Tregs is an important early marker of diagnosis and prognosis of sepsis. Until now, there is no study about Tregs in heat stroke domestic and abroad. So we learn from the research methods of sepsis immune disorders to explore the changes of immune system of heat stroke.Objective:By simulating hot climate, classic and exertional heat stroke rat models were built. In order to understand heat stroke rats immune status and possible reasons, spleen and arterial blood CD4+CD25+Foxp3+ regulatory T cells (Tregs) levels and its apoptosis rate in spleen at different time points was detected, as well as blood inflammatory cytokines.Methods:140 adult male rats were randomly divided into 3 groups:normal control group (N-Control, N=20), classic heat stroke group (CHS, N= 60) and exertional heat stroke group (EHS,N=60). The N-Control group did not make any processing, After anesthesia, rats in CHS group were put into a hot and humid environment, rats in EHS group were trained on treadmill in hot and humid environment. CHS and EHS group according to the sampling time points after models were successfully built was divided into six subgroups (Oh,6h,12h,24h,48h,72h),10 rats in each subgroup. At the scheduled time point, rats of each subgroup through the right carotid artery catheter to return fresh arterial blood into heparin anti-coagulated EP pipe and biochemical tube, the spleen was taken through laparotomy. Using automatic biochemical detector to detect the blood biochemical indexes (AST, ALT, CK, Cr), Flow cytometry to detect arterial blood and spleen CD4+CD25+Foxp3+/CD4+ T cells and spleen Tregs apoptosis rate, ELISAto detect serum TNF-alpha, IL-2, IL-6, IL-10, TGF-beta levels.Results:1.By detecting serum AST, ALT, CK, Cr levels in 6h after models were made, CHS group compared with N-Control group differences were statistically significant, EHS group compared with CHS group and N-Control group differences were all statistically significant, confirming CHS and EHS rat models were successfully built. Serum TNF-alpha, IL-2, IL-6, IL-10, levels rising rapidly in early period of CHS group, with the peak at 12h or 24h, and then decreased gradually, serum TGF-beta of CHS group showed a trend of gradual increase, at all time points they were significantly higher than N-control group. The change tendency of serum TNF-alpha, IL-2, IL-6, IL-10, TGF-beta in EHS group were similar to CHS group, but each time point of cytokine levels were higher than that of CHS group.2. Tregs proportion of artery blood and spleen in CHS group showed a trend of gradually increase, they were slightly lower than in N-Control group at first 12h or 24h, after 24h they were higher than in N-Control group. Tregs proportion of artery blood and spleen in EHS group were gradually reduced over time, the former were slightly higher than in N-Control group at 0 h, less than in N-Control group afterwards, the latter were higher than in N-Control group at first 12 h, Starting from 24h they were less than in N-Control group.3. Tregs apoptosis proportion of spleen in CHS group showed a trend of gradual decline over time, in the first 12h they were higher than that in N-Control group, after 24h they were lower than in N-Control group. Tregs apoptosis proportion of spleen in EHS group showed a trend of gradual increase over time, and were higher than N-Control group at all time points.Conclusion:1. In early period after CHS and EHS rats collapse, a flood of pro-inflammatory cytokines and anti-inflammatory cytokines were released into blood, the pro-inflammatory and anti-inflammatory reaction level in EHS group were stronger than in CHS group at all time points.2. Tregs proportion of peripheral blood and spleen in CHS group showed a rising trend during the early period, and is consistent with the spleen Tregs apoptosis rate, indicated that immunosuppression may had appeared in the early onset of CHS rats.3. Tregs proportion of peripheral blood and spleen in EHS group showed a trend of gradually reduce within 72 h of the experimental observation and is consistent with the spleen Tregs apoptosis rate, but the trend were opposite to CHS group. This may be due to the excessive inflammatory reaction promoted the apoptosis of Tregs. |
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