Unfractionated heparin inhibits lipopolysaccharide-induced expression of chemokines in human endothelial cells through nuclear factor-κB signaling pathway / 中华危重病急救医学

ABSTRACT

Objective To determine the effect of unfractionated heparin (UFH) on lipopolysaccharide (LPS)-induced expression of chemokines and nuclear factor-κB (NF-κB) signaling pathway. Methods Human pulmonary microvascular endothelial cells (HPMECs) were cultured in vitro, and the cells between passages 3 and 5 were used in the experiments. The cells were divided into control group, LPS challenge group, 1 kU/L or 10 kU/L UFH+LPS group, and NF-κB inhibitor N-tosyl-L-lysyl chloromethyl-ketone (TLCK) group (TLCK+LPS group). HPMECs in LPS challenge group were treated with 10 mg/L LPS. UFH pretreatment with different dosages groups were treated with 1 kU/L or 10 kU/L UFH 15 minutes before LPS challenge. Cells in the TLCK+LPS group were treated with 10 μmol/L of TLCK 30 minutes before the addition of LPS, and HPMECs in control group were treated with an equal volume of phosphate-buffered saline (PBS) instead. The cells were harvested 1 hour after LPS challenge, and the nuclear translocation of NF-κB was determined by immunofluorescence assay to detect the effect of UFH on NF-κB activation. The levels of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) in cell culture supernatants were determined by enzyme linked immunosorbent assay (ELISA) 3 hours and 6 hours after LPS challenge to detect the effect of UFH on LPS induced expression of chemokines and its mechanism of effect on NF-κB signaling pathway in HPMECs. Results ① In the control group, NF-κB was mostly located in the cytosol as shown by immunofluorescence. Treatment of HPMECs with LPS significantly increased the translocation of NF-κB from the cytosol to nucleus. UFH suppressed LPS-induced NF-κB activation both in 1 kU/L and 10 kU/L dosages, and 10 kU/L UFH gave even better results. ② Compared with control group, the levels of IL-8 and MCP-1 in the supernatants in LPS challenge group were significantly increased at 3 hours and 6 hours after LPS challenge [IL-8 (ng/L) 387.1±26.4 vs. 23.8±8.1 at 3 hours, 645.5±69.6 vs. 125.7±18.7 at 6 hours; MCP-1 (ng/L) 3 654.9±467.9 vs. 721.6±61.3 at 3 hours, 8 178.5±792.6 vs. 1 324.7±148.7 at 6 hours, all P < 0.05]. Compared with that of LPS challenge group, in 1 kU/L and 10 kU/L UFH pretreatment groups, the levels of IL-8 and MCP-1 were significantly decreased [IL-8 (ng/L) 315.3±24.8, 275.8±31.1 vs. 387.1±26.4 at 3 hours, 557.8±43.3, 496.9±38.7 vs. 645.5±69.6 at 6 hours; MCP-1 (ng/L) 2 924.1±267.9, 2 668.3±522.6 vs. 3 654.9±467.9 at 3 hours, 7 121.7±557.2, 6 563.9±576.4 vs. 8 178.5±792.6 at 6 hours, all P < 0.05]. The results indicated that 10 kU/L UFH yielded better results. However, inhibition study using the known NF-κB inhibitor TLCK could decrease LPS-induced increase in IL-8 and MCP-1 levels [IL-8 (ng/L) 162.4±21.3 vs. 387.1±26.4 at 3 hours, 274.1±22.6 vs. 645.5±69.6 at 6 hours; MCP-1 (ng/L) 1 478.2±138.5 vs. 3 654.9±467.9 at 3 hours; 3 667.6±259.4 vs. 8 178.5±792.6 at 6 hours, all P < 0.05]. Conclusions The levels of IL-8 and MCP-1 were increased obviously in LPS treated HPMECs. UFH might suppress LPS-activated NF-κB signaling pathway, contributing to the inhibitory effects of chemokines in HPMECs.