Anti-inflammatory effects of ursodeoxycholic acid by lipopolysaccharide-stimulated inflammatory responses in RAW 264.7 macrophages

Abstract

Purpose The aim of this study was to investigate the anti-inflammatory effects of Ursodeoxycholic acid (UDCA) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Methods We induced an inflammatory process in RAW 264.7 macrophages using LPS. The anti-inflammatory effects of UDCA on LPS-stimulated RAW 264.7 macrophages were analyzed using nitric oxide (NO). Pro-inflammatory and anti-inflammatory cytokines were analyzed by quantitative real time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). The phosphorylations of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 in mitogen-activated protein kinase (MAPK) signaling pathways and nuclear factor kappa-light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) signaling pathways were evaluated by western blot assays. Results UDCA decreased the LPS-stimulated release of the inflammatory mediator NO. UDCA also decreased the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin 1-α (IL-1α), interleukin 1-β (IL-1β), and interleukin 6 (IL-6) in mRNA and protein levels. In addition, UDCA increased an anti-inflammatory cytokine interleukin 10 (IL-10) in the LPS-stimulated RAW 264.7 macrophages. UDCA inhibited the expression of inflammatory transcription factor nuclear factor kappa B (NF-κB) in LPS-stimulated RAW 264.7 macrophages. Furthermore, UDCA suppressed the phosphorylation of ERK, JNK, and p38 signals related to inflammatory pathways. In addition, the phosphorylation of IκBα, the inhibitor of NF-κB, also inhibited by UDCA. Conclusion UDCA inhibits the pro-inflammatory responses by LPS in RAW 264.7 macrophages. UDCA also suppresses the phosphorylation by LPS on ERK, JNK, and p38 in MAPKs and NF-κB pathway. These results suggest that UDCA can serve as a useful anti-inflammatory drug.