LAUSR

Abstract The bile acid‐phospholipid conjugate ursodeoxycholyl oleoyl‐lysophophatidylethanolamide (UDCA‐18:1LPE) is an anti‐inflammatory and anti‐fibrotic agent as previously shown in cultured hepatocytes and hepatic stellate cells as well as in in vivo models of liver injury. We hypothesize that UDCA‐18:1LPE may directly inhibit the activation of immune cells. We found that UDCA‐18:1LPE was capable of inhibiting the migration of phorbol ester‐differentiated human THP‐1 cells. We examined anti‐inflammatory activity of UDCA‐18:1LPE during activation of THP1‐derived macrophages. Treatment of these macrophages by bacterial lipopolysaccharide (LPS) for 24 h induced the release of pro‐inflammatory cytokines TNF‐&agr;, IL‐6 and IL‐1&bgr;. This release was markedly inhibited by pretreatment with UDCA‐18:1LPE by ˜ 65–90%. Derivatives with a different fatty‐acid chain in LPE moiety also exhibited anti‐inflammatory property. Western blotting and indirect immunofluorescence analyses revealed that UDCA‐18:1LPE attenuated the expression of phosphorylated p38, MKK4/MKK7, JNK1/2, and c‐Jun as well as nuclear translocation of NF‐&kgr;B by ˜ 22–86%. After LPS stimulation, the Toll‐like receptor adaptor proteins, myeloid differentiation factor 88 and TNF receptor associated factor 6, were recruited into lipid rafts and UDCA‐18:1LPE inhibited this recruitment by 22% and 58%, respectively. Moreover, LPS treatment caused a decrease of the known cytoprotective lysophosphatidylcholine species containing polyunsaturated fatty acids by 43%, and UDCA‐18:1LPE co‐treatment reversed this decrease. In conclusion, UDCA‐18:1LPE and derivatives inhibited LPS inflammatory response by interfering with Toll‐like receptor signaling in lipid rafts leading to an inhibition of MAPK and NF‐&kgr;B activation. These conjugates may represent a class of lead compounds for development of anti‐inflammatory drugs.