ABSTRACT
<p><b>OBJECTIVE</b>To explore the anti-inflammatory mechanisms of high density lipoprotein (HDL) by observing the effects of apoprotein (apo)AI, a major protein component of HDL, on the inflammatory macrophage cell polarity.</p><p><b>METHODS</b>Cultured mice marrow-derived macrophages were stimulated with lipopolysaccharide and interferon after 10 µg/ml of apoAI were added to the macrophages for 24 hours. The expression of membrane molecules CD16/32, CD206 were detected by fluorescence activated cell sorting (FACS). ELISA was used to detect the secretion of IL-10 and IL-12. Real-time quantitative PCR was used to detect the mRNA expression of TLR4, MyD88 and IRF5.</p><p><b>RESULTS</b>Compared to macrophages stimulated by interferon and lipopolysaccharide but without pretreatment with apoAI, pre-incubation with apoAI significantly downregulated the expression of CD16/32 (91.17% ± 1.99% vs.50.47% ± 1.02%, P < 0.05), IL-12 [(747.27 ± 3.74)pg/ml vs. (73.80 ± 4.56)pg/ml, P < 0.05], upregulated the expression of CD206(0.33% ± 0.12% vs. 3.00% ± 0.36%, P < 0.05), IL -10 expression [(23.56 ± 4.30) pg/ml vs.(32.91 ± 2.47) pg/ml, P < 0.05], and reduced the mRNA expression of TLR4 (1.000 ± 0.025 vs.0.708 ± 0.003, P < 0.05) , MyD88 (1.591 ± 0.005 vs. 1.341 ± 0.005, P < 0.05) , IRF5 (0.954 ± 0.005 vs. 0.463 ± 0.003, P < 0.05) .</p><p><b>CONCLUSION</b>ApoAI enhances the switch of inflammatory macrophages to anti-inflammatory macrophages possibly through inhibiting TLR4-MyD88-IRF5 pathway.</p>
Subject(s)
Animals , Female , Mice , Apolipoprotein A-I , Pharmacology , Cell Line , Interferon Regulatory Factors , Metabolism , Interleukin-10 , Metabolism , Interleukin-12 , Metabolism , Lectins, C-Type , Metabolism , Macrophages , Allergy and Immunology , Metabolism , Mannose-Binding Lectins , Metabolism , Mice, Inbred C57BL , Myeloid Differentiation Factor 88 , Metabolism , Receptors, Cell Surface , Metabolism , Receptors, IgG , Metabolism , Toll-Like Receptor 4 , MetabolismABSTRACT
AIM: To study the characteristic of liver X receptor alpha (LXRα), its target gene expression and cholesterol efflux in human macrophages treated with atorvastatin. METHODS: Human monocyte-derived macrophages were collected and cultured. Macrophages were treated with or without atorvastatin. Apolipoprotein A-I mediated human monocyte-derived macrophage cholesterol efflux was detected by liquid scintillation counting method. Reverse transcription-polymerase chain reaction (RT-PCR) was used to evaluate the mRNA expression of LXRα and some of its target genes ABCA1, SREBP2, CETP, PLTP, apoE, MMP-9 and MIP-1α. The protein expression of LXRα, ABCA1, MMP-9 and MIP-1α was determined by Western blotting. RESULTS: Pre-incubation of human monocyte-derived macrophages with atorvastatin dose dependently (1-2 μmol/L) stimulated cholesterol efflux mediated by apolipoprotein A-I. Atorvastatin also increased the mRNA expression of LXRα, ABCA1, SREBP2, CETP, PLTP, and protein expression of LXRα, ABCA1, but decreased the expression of MMP-9 and MIP-1α at both mRNA and protein levels. CONCLUSION: Atorvastatin enhances the cholesterol efflux, upregulates LXR and some genes associated with cholesterol metabolism and inhibits inflammatory responses in macrophages, indicating that statins may affect the formation of foam cells by activating LXR signaling pathway.