Effect of high volume hemofiltration on expression of Toll-like receptor 4 in myocardium in endotoxin induced shock in dogs

Abstract

To investigate the effects of high volume hemofiltration (HVHF) on the expression of Toll-like receptor 4 (TLR4) mRNA in myocardium in endotoxin (lipopolysaccharide, LPS) induced shock in dogs. Sixteen healthy male dogs were injected with LPS 650 microg/kg via central vein to reproduce the model of endotoxin shock. All dogs were divided randomly into two groups: control group and therapy group, with 8 dogs in each group. Contents of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), IL-10 in circulation were measured by radioimmunological method. The expression levels of TLR4 mRNA in all group were measured by reverse transcription-polymerase chain reaction (RT-PCR). Change in myocardial histopathology was observed and analyzed with the aid of electron microscope. The contents of TNF-alpha (microg/L: 0.59+/-0.15, 0.51+/-0.12, 0.41+/-0.10), IL-6 (ng/L: 11.08+/-2.83, 9.82+/-2.58, 8.25+/-2.05), IL-10 (microg/L: 57.28+/-5.93, 53.81+/-5.83, 50.67+/-6.33) in therapy group were found to have decreased significantly at 1, 2, and 4 hours after HVHF compared with those when the model was completed [(0.84+/-0.16) microg/L, (16.97+/-2.50) ng/L, (70.86+/-5.43) microg/L], showing a continuous trend of lowering (all P<0.01). The contents of TNF-alpha, IL-6, IL-10 in therapy group were lower than those in control group significantly at any time point [TNF-alpha (microg/L): 0.75+/-0.14, 0.74+/-0.11, 0.72+/-0.11, IL-6 (ng/L): 15.33+/-3.20, 14.66+/-3.24, 14.20+/-3.33, IL-10 (microg/L): 71.54+/-4.73, 70.71+/-4.34, 69.35+/-4.60, all P<0.01]. Compared with control group, HVHF treatment group could down-regulate mRNA expression of TLR4 in myocardium (t=3.58, P<0.01). Correlation analysis revealed significant positive-correlation between tissue TLR4 mRNA expression and contents of TNF-alpha, IL-6, IL-10 in circulation (r(1)=0.785, r(2)=0.569, r(3)=0.653, all P<0.05). Injury to the myocardium was significantly ameliorated in therapy group compared with control group as shown by electron microscopic observation. HVHF can down-regulate mRNA expression of TLR4 in myocardium in LPS induced shock in dogs, and myocardial inflammatory response was alleviated resulting in amelioration of myocardial injury.