Piraino Giovanna, Cook James A, O'Connor Michael, Hake Paul W, Burroughs Timothy J, Teti Diana, Zingarelli Basilia
Cincinnati Children's Hospital Medical Center, Division of Critical Care Medicine, Cincinnati, OH 45229, USA.
Shock. 2006 Aug;26(2):146-53. doi: 10.1097/01.shk.0000223121.03523.69.
Peroxisome proliferator-activated receptor-gamma (PPARgamma) and liver X receptor-alpha (LXRalpha) are nuclear ligand-activated transcription factors, which regulate lipid metabolism and inflammation. Murine J774.2 macrophages were stimulated with Escherichia coli lipopolysaccharide (concentration, 10 microg/mL) with or without the PPARgamma ligand, 15-deoxy-Delta prostaglandin J2 (15d-PGJ2), or the LXRalpha ligands, 22(R)-hydroxycholesterol and T0901317 (concentration range, 0.01-10 micromol/L), alone or in combination. Nitric oxide (NO) metabolites and tumor necrosis factor alpha production, inducible NO synthase expression, and mitochondrial respiration were measured. When added to the cells as single agents, 15d-PGJ2, 22(R)-hydroxycholesterol, or T0901317 reduced the lipopolysaccharide-induced NO and tumor necrosis factor alpha production and the inducible NO synthase expression, and partially maintained mitochondrial respiration in a concentration-dependent manner. When added to the cells in combination at suboptimal concentrations, 15d-PGJ2 with 22(R)-hydroxycholesterol, or 15d-PGJ2 with T0901317, exerted anti-inflammatory effects similar to much higher concentrations (10,000-fold to 100,000-fold) of each ligand alone. The anti-inflammatory effects of these ligands, alone or in combination, were associated with reduction of nuclear factor-kappaB activation and with enhancement of PPARgamma DNA binding. LXRalpha expression was upregulated in response to 15d-PGJ2 and to the LXRalpha ligands when added alone or in combination. Immunoprecipitation experiments revealed that PPARgamma interacted with LXRalpha. Our data demonstrate that the PPARgamma ligand, 15d-PGJ2, and the LXRalpha ligands, 22(R)-hydroxycholesterol and T0901317, although binding to different nuclear receptors (i.e., PPARgamma and LXRalpha, respectively), affect mediator production through common cell signaling events and exert a synergistic potentiation in a combined treatment at suboptimal concentrations. Thus, our data suggest that PPARgamma and LXRalpha may interact in controlling the inflammatory response in macrophages.
过氧化物酶体增殖物激活受体γ（PPARγ）和肝X受体α（LXRα）是核配体激活的转录因子，可调节脂质代谢和炎症反应。用大肠杆菌脂多糖（浓度为10μg/mL）刺激小鼠J774.2巨噬细胞，分别单独或联合使用PPARγ配体15-脱氧-Δ前列腺素J2（15d-PGJ2）或LXRα配体22（R）-羟基胆固醇和T0901317（浓度范围为0.01 - 10μmol/L）。检测一氧化氮（NO）代谢产物、肿瘤坏死因子α的产生、诱导型NO合酶的表达以及线粒体呼吸。当单独作为试剂添加到细胞中时，15d-PGJ2、22（R）-羟基胆固醇或T0901317可降低脂多糖诱导的NO和肿瘤坏死因子α的产生以及诱导型NO合酶的表达，并以浓度依赖的方式部分维持线粒体呼吸。当以次优浓度联合添加到细胞中时，15d-PGJ2与22（R）-羟基胆固醇或15d-PGJ2与T0901317产生的抗炎作用类似于单独使用每种配体高得多的浓度（10000倍至100000倍）时的效果。这些配体单独或联合使用的抗炎作用与核因子κB激活的降低以及PPARγ DNA结合的增强有关。单独或联合添加时，15d-PGJ2和LXRα配体可上调LXRα的表达。免疫沉淀实验表明PPARγ与LXRα相互作用。我们的数据表明，PPARγ配体15d-PGJ2和LXRα配体22（R）-羟基胆固醇及T0901317虽然分别与不同的核受体（即PPARγ和LXRα）结合，但通过共同的细胞信号事件影响介质的产生，并在次优浓度的联合治疗中发挥协同增强作用。因此，我们的数据表明PPARγ和LXRα可能在控制巨噬细胞的炎症反应中相互作用。
