Abstract:

Objective To explore the activating effect of the free fatty acid (FFA) mixture on the toll-like receptor-4 (TLR4) of rat pulmonary microvascular endothelial cells (RRPMVECs) and the mechanism of FFA-induced inflammation response. Methods RRPMVECs cultured in vitro were prepared by FFA of different concentrations. The expression of TLR4 protein was detected by the Western blotting. RRPMVECs were then divided into the TLR4 siRNA group (transfected by TLR4 siRNA), scramble siRNA group (transfected by scramble siRNA), and negative control group. All groups were prepared by FFA of 0.1 mmol/L, LPS of 10 ng/mL, TNF-α of 5 ng/mL, and blank medium, respectively. The expressions of TLR4 mRNA and IKKβ mRNA were detected by the Real-Time PCR. The expressions of P-IκBα and NF-κB were measured by the Western blotting. The expression of inflammatory factor IL-1β in the cell culture supernatant was detected by the ELISA. Results The relative expression of TLR4 protein in RPMVECs increased significantly after being prepared by FFA of 0.1 mmol/L (P<0.05) and increased with the concentration of FFA. The relative expressions of TLR4 mRNA of the scramble siRNA group and negative control group increased significantly after being prepared by LPS and FFA (P<0.05) and did not significantly changed after being prepared by TNF-α. The expression of TLR4 mRNA of the TLR4 siRNA group did not significantly changed after being prepared by LPS, FFA, and TNF-α. The relative expressions of IKKβmRNA, p-IκBα, and IL-1β in RPMVECs of the scramble siRNA group and negative control group increased significantly after being prepared by LPS, FFA, and TNF-α (P<0.05). The interference of TLR4 siRNA could suppress the expressions of groups prepared by FFA and LPS, but did not suppress the expressions of groups prepared by TNF-α. Conclusion FFA induces the inflammation response of RPMVECs through the TLR4/IKKβ/NF-κB signaling pathway.

Key words: fat embolism syndrome, free fatty acid, lipolysaccharide, rat pulmonary microvascular endothelial cells, toll-like receptor-4 signaling, inflammation response