OBJECTIVEIn order to investigate the evidence of the synergistic effects of bacterial components, to observe the relationship of the expression of lipopolysaccharide (LPS) receptors [CD14, Toll-like receptor 4 (TLR4), scavenger receptor (SR)], lipoprotein receptor (TLR2) and bacterial DNA receptor (TLR9) with pulmonary injury in abdominal infection-induced sepsis.

METHODS30 mice were used and randomly divided into cecal ligation puncture (CLP) (n = 15) and sham (n = 15) groups. The animals were respectively sacrificed 8, 12 and 24 (each point n = 5) hours following CLP and sham CLP. The lungs were removed and immediately stored in liquid nitrogen for TLRs mRNA, tumor necrosis factor (TNF) alpha and myeloperoxidase (MPO) assay. To detect the expression of CD14, TLR4, SR, TLR2 and TLR9 mRNA by reverse-transcription polymerase chain reaction, to detect the TNF-alpha content of the lung tissue by enzyme-labeled immunosorbent assay, and to assay the MPO activity of the lung tissue spectrophotometer.

RESULTSIt was found that the expression of receptors for LPS, BLP and bacterial DNA in pulmonary tissues was markedly changed in CLP-induced sepsis, showing upregulation of CD14 mRNA (1.143 +/- 0.139, t = 0.022, P < 0.05), TLR2 mRNA (0.418 +/- 0.102, t = 0.021, P < 0.05), TLR4 mRNA (0.595 +/- 0.052, t = 0.0001, P < 0.01) and TLR9 mRNA (0.743 +/- 0.178, t = 0.0023, P < 0.01) at different degrees (P < 0.05 or P < 0.01) after postinjury 8 h, among which the expression of TLR9 mRNA kept increasing. The expression of SR mRNA (8 h: 0.659 +/- 0.159; 12 h: 0.429 +/- 0.061; 24 h: 0.300 +/- 0.045; t = 0.029, P < 0.05; t = 0.001, P < 0.01; t = 0.003, P < 0.01) showed continuous down-regulation.

CONCLUSIONThere was a marked correlation between the changes of pattern-recognition receptor expression and the increases of MPO and TNF-alpha levels in pulmonary tissues.