PPARγ基因多态性与冠心病及其危险因素相关性研究概况

过氧化物酶体增殖物激活受体（peroxisome proliferator-activated receptors,PPARs）属于核激素受体家族。PPARs包括3个亚型即α亚型δ亚型和γ亚型,PPARγ2亚型有两个常见多态：C1431T和Pro12Ala。研究证实在人类PPARγ基因多态性与动脉粥样硬化的发生发展密切相关,可导致冠心病的发生发展,并与冠状动脉粥样硬化性心脏病多个危险因素,如2型糖尿病、高血压、肥胖、血脂异常、代谢综合征有关。因此PPARγ基因多态性不仅直接参与了冠心病发生发展的多个环节,并可通过增加冠心病的危险因素来进一步促进冠心病的发生与发展。临床通过测定PPARγ基因多态性有可能分析出发生2型糖尿病、高血压、代谢综合征、血脂异常、肥胖和冠心病发病的可能性和风险,发现与诊断冠心病的高危人群。     

Relationship between peroxisome proliferator‐activated receptor alpha activity and cellular concentration of 14 perfluoroalkyl substances in HepG2 cells

Peroxisome proliferator‐activated receptor alpha (PPARα) is a molecular target for perfluoroalkyl substances (PFASs). Little is known about the cellular uptake of PFASs and how it affects the PPARα activity. We investigated the relationship between PPARα activity and cellular concentration in HepG2 cells of 14 PFASs, including perfluoroalkyl carboxylates (PFCAs), perfluoroalkyl sulfonates and perfluorooctane sulfonamide (FOSA). Cellular concentrations were determined by high‐performance liquid chromatography–tandem mass spectrometry and PPARα activity was determined in transiently transfected cells by reporter gene assay. Cellular uptake of the PFASs was low (0.04–4.1%) with absolute cellular concentrations in the range 4–2500 ng mg^?1 protein. Cellular concentration of PFCAs increased with perfluorocarbon chain length up to perfluorododecanoate. PPARα activity of PFCAs increased with chain length up to perfluorooctanoate. The maximum induction of PPARα activity was similar for short‐chain (perfluorobutanoate and perfluoropentanoate) and long‐chain PFCAs (perfluorododecanoate and perfluorotetradecanoate) (approximately twofold). However, PPARα activities were induced at lower cellular concentrations for the short‐chain homologs compared to the long‐chain homologs. Perfluorohexanoate, perfluoroheptanoate, perfluorooctanoate, perfluorononanoate (PFNA) and perfluorodecanoate induced PPARα activities >2.5‐fold compared to controls. The concentration–response relationships were positive for all the tested compounds, except perfluorooctane sulfonate PFOS and FOSA, and were compound‐specific, as demonstrated by differences in the estimated slopes. The relationships were steeper for PFCAs with chain lengths up to and including PFNA than for the other studied PFASs. To our knowledge, this is the first report establishing relationships between PPARα activity and cellular concentration of a broad range of PFASs.     

姜黄素通过上调PPARγ抑制糖基化终末产物诱导的软骨细胞凋亡及线粒体功能损伤

目的观察姜黄素(curcumin)对糖基化终末产物(AGEs)诱导的软骨细胞凋亡及线粒体功能损伤的作用,并探讨相关机制是否与姜黄素上调过氧化物酶体增殖物激活受体-γ(PPARγ)相关。方法原代培养家兔膝关节软骨细胞;TUNEL染色法检测细胞凋亡;Rhodamine-123试剂盒检测线粒体跨膜电位(△Ψm);ATP试剂盒检测线粒体ATP生成;分光光度法检测caspase-3活性;Western blot检测PPARγ、细胞色素C、Bax及Bcl-2蛋白表达;real-time PCR检测PPARγmRNA含量;DNA-binding法检测PPARγ活性。结果 AGEs(200 mg·L-1)可明显诱导兔软骨细胞凋亡,同时线粒体跨膜电位(△Ψm)降低、ATP生成减少,caspase-3活性增加,细胞色素C释放增加,Bax/Bcl-2的比值增加;线粒体通透性转换孔的抑制剂环孢霉素A(Cs A,100 nmol·L-1)可以明显抑制AGEs诱导的细胞凋亡;PPARγ特异性激动剂吡格列酮及姜黄素均可明显抑制AGEs诱导的软骨细胞凋亡及线粒体功能损伤,给予PPARγ特异性抑制剂GW9662 10μmol·L-1预处理后,可以明显拮抗姜黄素的保护作用。同时,姜黄素可以明显上调AGEs诱导的PPARγ活性的降低,并伴随PPARγ相应的mRNA及蛋白表达水平的升高。结论姜黄素通过上调PPARγ,有效地保护AGEs诱导的软骨细胞线粒体损伤,从而抑制AGEs诱导的软骨细胞凋亡。     

Dose–response approaches for nuclear receptor-mediated modes of action for liver carcinogenicity: Results of a workshop

A public workshop, organized by a Steering Committee of scientists from government, industry, universities and research organizations, was held at the National Institute of Environmental Health Sciences (NIEHS) in September, 2010. The workshop explored the dose–response implications of toxicant modes of action (MOA) mediated by nuclear receptors. The dominant paradigm in human health risk assessment has been linear extrapolation without a threshold for cancer, and estimation of sub-threshold doses for non-cancer and (in appropriate cases) cancer endpoints. However, recent publications question the application of dose–response modeling approaches with a threshold. The growing body of molecular toxicology information and computational toxicology tools has allowed for exploration of the presence or absence of sub-threshold doses for a number of receptor-mediated MOAs. The workshop explored the development of dose–response approaches for nuclear receptor-mediated liver cancer, within a MOA Human Relevance Framework (HRF). Case studies addressed activation of the AHR, the CAR and the PPARα. This article describes the workshop process, key issues discussed and conclusions. The value of an interactive workshop approach to apply current MOA/HRF frameworks was demonstrated. The results may help direct research on the MOA and dose–response of receptor-based toxicity, since there are commonalities for many receptors in the basic pathways involved for late steps in the MOA, and similar data gaps in early steps. Three additional papers in this series describe the results and conclusions for each case-study receptor regarding its MOA, relevance of the MOA to humans and the resulting dose–response implications.     

The phenotype of a flavin-containing monooyxgenase knockout mouse implicates the drug-metabolizing enzyme FMO1 as a novel regulator of energy balance

Flavin-containing monooxygenases (FMOs) of mammals are thought to be involved exclusively in the metabolism of foreign chemicals. Here, we report the unexpected finding that mice lacking Fmos 1, 2 and 4 exhibit a lean phenotype and, despite similar food intake, weigh less and store less triglyceride in white adipose tissue (WAT) than wild-type mice. This is a consequence of enhanced whole-body energy expenditure, due mostly to increased resting energy expenditure (REE). This is fuelled, in part, by increased fatty acid β-oxidation in skeletal muscle, which would contribute to depletion of lipid stores in WAT. The enhanced energy expenditure is attributed, in part, to an increased capacity for exercise. There is no evidence that the enhanced REE is due to increased adaptive thermogenesis; instead, our results are consistent with the operation in WAT of a futile energy cycle. In contrast to FMO2 and FMO4, FMO1 is highly expressed in metabolic tissues, including liver, kidney, WAT and BAT. This and other evidence implicates FMO1 as underlying the phenotype. The identification of a novel, previously unsuspected, role for FMO1 as a regulator of energy homeostasis establishes, for the first time, a role for a mammalian FMO in endogenous metabolism. Thus, FMO1 can no longer be considered to function exclusively as a xenobiotic-metabolizing enzyme. Consequently, chronic administration of drugs that are substrates for FMO1 would be expected to affect energy homeostasis, via competition for endogenous substrates, and, thus, have important implications for the general health of patients and their response to drug therapy.     

Association of Bezafibrate Treatment With Reduced Risk of Cancer in Patients With Coronary Artery Disease

ObjectiveTo evaluate the association between bezafibrate, a drug used to treat hypertriglyceridemia, and long-term cancer incidence in patients with coronary artery disease (CAD).Patients and MethodsThe study comprised 2980 patients with CAD (mean age, 60 years; 2729 [91.6%] men) who were free of cancer and were enrolled in the Bezafibrate Infarction Prevention study, a double-blind trial conducted between May 1, 1990, and January 31, 1993, in 18 cardiology departments in Israel. Patients randomized to receive 400 mg of bezafibrate (n=1486) or placebo (n=1494) daily for a median of 6.2 years (range, 4.7-7.6 years) were followed up for incidence of cancer through the Israeli National Cancer Registry and all-cause death through the Population Registry of the State of Israel until December 31, 2013. Cox proportional hazards and Fine and Gray survival models were used to assess the bezafibrate-cancer association.ResultsClinical characteristics and laboratory values were well balanced between the 2 groups at the study entry. Over a median follow-up of 22.5 years (range, 21.2-23.9 years), cancer developed in 753 patients. With death considered a competing event, the cumulative incidence of cancer at the end of the follow-up was lower in the bezafibrate vs the placebo group (23.9%; 95 CI, 21.9%-26.1% vs 27.2%; 95 CI, 25.1%-29.4%; P=.04). The hazard ratio for cancer in the bezafibrate vs placebo groups was 0.86 (95% CI, 0.74-0.99). In mediation analysis, the association between bezafibrate treatment and cancer incidence was not sensitive to adjustment for on-trial lipid levels but was attenuated on adjustment for on-trial fibrinogen levels.ConclusionBezafibrate treatment is associated with reduced risk of cancer among patients with CAD. Fibrinogen, but not lipid lowering, is linked to this association.     

Inhibition of microRNA-17-5p reduces the inflammation and lipid accumulation,and up-regulates ATP-binding cassette transporterA1 in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease of the arterial wall. Macrophages are considered to be closely associated with the development and progression of AS. However, the precise mechanism of miR-17-5p in the macrophages under AS remains incompletely clarified. This study investigated the regulatory effect of miR-17-5p on the inflammation and lipid accumulation in mouse macrophages both in vivo and in vitro. It was found that miR-17-5p was highly expressed with lowered ATP-binding cassette transporterA1 (ABCA1) level in the peripheral blood leucocytes (PBLs) of AS patients. Moreover, the level of miR-17-5p was up-regulated in the macrophages of ApoE^?/? mice fed with a high-cholesterol diet. Furthermore, we injected miR-17-5p antagomir into AS mice or transfected miR-17-5p inhibitors into mouse macrophage RAW264.7 cells. Results showed that downregulation of miR-17-5p significantly reduced the production of inflammatory cytokines, inhibited the lipid accumulation and up-regulated ABCA1, and activated peroxisome proliferator-activated receptor (PPAR) γ/Liver X receptor (LXR) α signaling pathway. Additionally, ABCA1 was found to be a target of miR-17-5p by directly binding to 3′-untranslated region (3′-UTR) of its mRNA. Our study indicates a novel regulatory mechanism for miR-17-5p by interacting with ABCA1, which could be a therapy-target for the treatment of AS.     

Ceramides are associated with inflammatory processes in human mediastinal adipose tissue

Background and AimCeramides are poorly characterized in human adipose tissue. The aim of this study was to investigate concentrations of different ceramide species in human subcutaneous and visceral adipose tissue depots and to determine associations between ceramides and global gene expression profiles.Methods and ResultsConcentrations of six ceramide species were determined in plasma and in subcutaneous and mediastinal adipose tissue from 10 overweight subjects (BMI 29.4 ± 4.9 kg/m²). In the adipose tissue biopsies gene expression arrays were performed and relationships between ceramides and gene expression analyzed. Immunostaining of the two adipose tissue depots was performed in an independent group of 10 patients. Mediastinal adipose tissue contained significantly higher concentrations (p < 0.05) of all six ceramide species than the subcutaneous depot. Of the six ceramides in plasma, concentrations of only two (Cer d18:1/18:0 and Cer d18:1/22:0) correlated significantly (p < 0.05) with the corresponding species in mediastinal adipose tissue, but there were no significant correlations between ceramides in plasma and subcutaneous adipose tissue. Multivariate analysis identified significant correlations between the total ceramide concentration and global gene expression within mediastinal, but not subcutaneous adipose tissue, according to cross-validation. Gene ontology analysis of genes related to ceramides in the mediastinal depot revealed that genes positively correlated with ceramides were associated mainly with immune and inflammatory categories, while genes negatively correlated with ceramides were associated mainly with lipid and carbohydrate metabolism.ConclusionsCeramides in human mediastinal adipose tissue may be involved in inflammation and lipid and carbohydrate metabolism.