iTRAQ-based proteomic analysis of endotoxin tolerance induced by lipopolysaccharide

The purpose of the present study was to investigate the differentially expressed proteins between endotoxin tolerance and sepsis. Cell models of an endotoxin tolerance group (ET group) and sepsis group [lipopolysaccharide (LPS) group] were established using LPS and evaluated using ELISA and flow cytometry methods. Differentially expressed proteins between the ET and the LPS groups were identified using isobaric tags for relative and absolute quantitation (iTRAQ) analysis and evaluated by bioinformatics analysis. The expression of core proteins was detected by western blotting. It was identified that the expression of tumor necrosis factor-α and interleukin-6 was significantly decreased in the ET group compared with the LPS group. Following high-dose LPS stimulation for 24 h, the positive rate of cluster of differentiation-16/32 in the ET group (79.07%) was lower when compared with that of the LPS group (94.27%; P<0.05). A total of 235 proteins were identified by iTRAQ, and 36 upregulated proteins with >1.2-fold differences and 27 downregulated proteins with <0.833-fold differences were detected between the ET and LPS groups. Furthermore, the expression of high mobility group (HMG)-A1 and HMGA2 in the ET group was higher compared with the LPS group following high-dose LPS stimulation for 4 h, while HMGB1 and HMGB2 exhibited the opposite expression trend under the same conditions. In conclusion, proteomics analysis using iTRAQ technology contributes to a deeper understanding of ET mechanisms. HMGA1, HMGA2, HMGB1 and HMGB2 may serve a crucial role in the development of ET.