Expression of TLR4 in splenocytes at early phase of severely burned rats and its implication / 第二军医大学学报

ABSTRACT

Objective:To investigate a potential role of Toll-like receptor 4(TLR4),a pathogen pattern recognition receptor, in the early phase of severely burned rats. Methods: Rats burn model(30% of total body surface area[TBSA], III grade) were established with vapor at 108°C for 8 seconds. Rats were sacrificed before and 2,5,12,24,48 and 72 h after burning, and the spleen specimens and peripheral blood samples were harvested. TLR4 mRNA and TNF-α mRNA expression in splenocyte was measured by reverse-transcription PCR (RT-PCR); the expression of TLR4 protein were measured by Western bloting; the endothelial toxicity concentration in plasma was detected by limulus lysate test. Results: It was found that the expression of TLR4 mRNA, TNF-α mRNA, TLR4 protein, and the level of ET were significantly increased in burned group compared with normal control group. The expression of TLR4 mRNA and protein peaked at 8 h after burning, the expession of TNF-α mRNA peaked at 12 h,and the level of ET peaked at 8 h after burning; the peak values of them were (3.66±0.51),(2.27±0.19), (1.65±0.23), and (11.68±2.63) Eu/ml,respectively,all significantly higher than those of the control group(P<0.01 or P< 0.05). The expression of TLR4 mRNA showed a positive correlation with that of ET and TNF-α mRNA(r=0.811,0.462, P< 0.01). Conclusion: Severe burn can cause endotoxemia and upregulate the expression of TLR4 and TNF-α in splenocytes. The up-regulation of TLR4 might participate in the pathological procedure of excessive inflammation.