Role of liver X receptors alpha agonist on expressions of LPS-induced inflammatory response associated factor IRAK-4 and NF-kappaB in Kupffer cells

摘要

Objective: To explore the role of activated liver X receptor a (LXRa) on the expressions of interleukin-1 receptor associated kinase-4 (IRAK-4) and NF-kappaB (NF-κB) in the inflammatory response which induced by LPS in the Kupffer cells and to investigate the possible mechanisms of LXRα negative regulation of inflammatory response. Methods: The Kupffer cells were isolated from male Kunming mice by collagen perfusion in situ. And these cells were divided into 4 groups: normal control group, LPS treatment group, LXRα agonist T0901317 treatment group, LPS and T0901317 combined treatment group. The LPS treatment group were treated with a final concentration of 1 μg/ml LPS in RPMI 1640 and cultured for 6 h, the T0901317 treatment group were treated with a final concentration of 5 μg/ml in RPMI 1640 and cultured for 24 h, and the combined treatment group received pre-culture for 24 h with a final concentration of 1 μg/ml T0901317 in RPMI 1640 and then cultured for 6 h with a final concentration of 5 μg/ml LPS in RPMI 1640. All groups were cultured for 30 h. The expression of LXRα, IRAK-4 and NF-κB at mRNA and protein levels were detected by real-time PCR and Western blotting, and the TNF-α and IL-1β levels were detected by ELISA. Results: The levels of LXRα mRNA and protein were highest in T0901317 group, and lowest in LPS group (P<0.05). The level of IRAK4 and NF-κB mRNAs and proteins were evidently lower in the Combined-treated group than in LPS group (P<0.05). And the level of TNF-α and IL-1 were observed highest in LPS group (P<0.05), but no difference among the Control group, T0901317 group and Combined-treated group (P>0.05). Conclusion: These date suggest that the LXR agonists can effectively up-regulate the expressions of LXRa mRNA and protein and inhibit the inflammatory response. This may be via down-regulating the expressions of IRAK4 and NF-κB at mRNA and protein levels.