Genome-wide analysis of LXRalpha activation reveals new transcriptional networks in human atherosclerotic foam cells

Increased physiological levels of oxysterols are major risk factors for developing atherosclerosis and cardiovascular disease. Lipid-loaded macrophages, termed foam cells, are important during the early development of atherosclerotic plaques. To pursue the hypothesis that ligand-based modulation of the nuclear receptor LXRalpha is crucial for cell homeostasis during atherosclerotic processes, we analysed genome-wide the action of LXRalpha in foam cells and macrophages. By integrating chromatin immunoprecipitation-sequencing (ChIP-seq) and gene expression profile analyses, we generated a highly stringent set of 186 LXRalpha target genes. Treatment with the nanomolar-binding ligand T0901317 and subsequent auto-regulatory LXRalpha activation resulted in sequence-dependent sharpening of the genome-binding patterns of LXRalpha. LXRalpha-binding loci that correlated with differential gene expression revealed 32 novel target genes with potential beneficial effects, which in part explained the implications of disease-associated genetic variation data. These observations identified highly integrated LXRalpha ligand-dependent transcriptional networks, including the APOE/C1/C4/C2-gene cluster, which contribute to the reversal of cholesterol efflux and the dampening of inflammation processes in foam cells to prevent atherogenesis

Foam Cell Specific LXRα Ligand

Objective The liver X receptor α (LXRα) is a ligand-dependent nuclear receptor and the major regulator of reverse cholesterol transport in macrophages. This makes it an interesting target for mechanistic study and treatment of atherosclerosis. Methods and Results We optimized a promising stilbenoid structure (STX4) in order to reach nanomolar effective concentrations in LXRα reporter-gene assays. STX4 displayed the unique property to activate LXRα effectively but not its subtype LXRβ. The potential of STX4 to increase transcriptional activity as an LXRα ligand was tested with gene expression analyses in THP1-derived human macrophages and oxLDL-loaded human foam cells. Only in foam cells but not in macrophage cells STX4 treatment showed athero- protective effects with similar potency as the synthetic LXR ligand T0901317 (T09). Surprisingly, combinatorial treatment with STX4 and T09 resulted in an additive effect on reporter-gene activation and target gene expression. In physiological tests the cellular content of total and esterified cholesterol was significantly reduced by STX4 without the undesirable increase in triglyceride levels as observed for T09. Conclusions STX4 is a new LXRα-ligand to study transcriptional regulation of anti-atherogenic processes in cell or ex vivo models, and provides a promising lead structure for pharmaceutical development

Hormetic shifting of redox environment by pro-oxidative resveratrol protects cells against stress

AbstractResveratrol has gained tremendous interest owing to multiple reported health-beneficial effects. However, the underlying key mechanism of action of this natural product remained largely controversial. Here, we demonstrate that under physiologically relevant conditions major biological effects of resveratrol can be attributed to its generation of oxidation products such as reactive oxygen species (ROS). At low nontoxic concentrations (in general <50µM), treatment with resveratrol increased viability in a set of representative cell models, whereas application of quenchers of ROS completely truncated these beneficial effects. Notably, resveratrol treatment led to mild, Nrf2-specific gene expression reprogramming. For example, in primary epidermal keratinocytes derived from human skin this coordinated process resulted in a 1.3-fold increase of endogenously generated glutathione (GSH) and subsequently in a quantitative reduction of the cellular redox environment by 2.61mVmmol GSH per g protein. After induction of oxidative stress by using 0.78% (v/v) ethanol, endogenous generation of ROS was consequently reduced by 24% in resveratrol pre-treated cells. In contrast to the common perception that resveratrol acts mainly as a chemical antioxidant or as a target protein-specific ligand, we propose that the cellular response to resveratrol treatment is essentially based on oxidative triggering. In physiological microenvironments this molecular training can lead to hormetic shifting of cellular defense towards a more reductive state to improve physiological resilience to oxidative stress

Data of oxygen- and pH-dependent oxidation of resveratrol

AbstractWe show here if under physiologically relevant conditions resveratrol (RSV) remains stable or not. We further show under which circumstances various oxidation products of RSV such as ROS can be produced. For example, in addition to the widely known effect of bicarbonate ions, high pH values promote the decay of RSV. Moreover, we analyse the impact of reduction of the oxygen partial pressure on the pH-dependent oxidation of RSV. For further interpretation and discussion of these focused data in a broader context we refer to the article “Hormetic shifting of redox environment by pro-oxidative resveratrol protects cells against stress” (Plauth et al., in press) [1]

Human Metapneumovirus RNA in Encephalitis Patient

We describe a fatal case of encephalitis that might be correlated with primary human metapneumovirus (HMPV) encephalitis. Postmortem HMPV RNA was detected in brain and lung tissue samples from the patient. Furthermore, HMPV RNA was found in culture fluids from cells coincubated with lung tissue

The clinical effectiveness and cost-effectiveness of abatacept, adalimumab, etanercept and tocilizumab for treating juvenile idiopathic arthritis: a systematic review and economic evaluation

Background: Juvenile idiopathic arthritis (JIA) is characterised by joint pain, swelling and limitation of movement caused by inflammation. Subsequent joint damage can lead to disability and growth restriction. Treatment commonly includes disease modifying anti-rheumatic drugs (DMARD) such as methotrexate. Clinical practice now favours newer drugs termed biologic DMARDs where indicated.Objective: To assess the clinical and cost-effectiveness of four biologic DMARDs (etanercept, abatacept, adalimumab and tocilizumab - with or without methotrexate where indicated) for the treatment of JIA (systemic or oligoarticular JIA excluded).Data sources: Electronic bibliographic databases including MEDLINE, EMBASE, The Cochrane Library and DARE were searched for published studies from inception to May 2015 for English language articles. Bibliographies of related papers, systematic reviews and company submissions were screened and experts were contacted to identify additional evidence.Review methods: Systematic reviews of clinical-effectiveness, health-related quality of life and cost-effectiveness were undertaken according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. A cost-utility decision analytic model was developed to compare estimated cost-effectiveness of biologic DMARDs versus methotrexate. The base case time horizon was 30 years and the model took a National Health Service (NHS) perspective, with costs and benefits discounted at 3.5%.Results: Four placebo-controlled RCTs met the inclusion criteria for the clinical-effectiveness review (one RCT evaluating each biologic DMARD). Only one RCT included UK participants. Participants had to achieve an American College of Rheumatology Pediatric (ACR Pedi) 30 response to open-label lead-in treatment in order to be randomised. An exploratory adjusted indirect comparison suggests that the four biologic DMARDs are similar with fewer disease flares and greater proportions with ACR Pedi 50 and 70 responses among participants randomised to continued biologic DMARD. However, confidence intervals were wide, the number of trials was low and there was clinical heterogeneity between trials. Open-label extensions of the trials showed that generally ACR responses remained constant or even increased after the double-blind phase. The proportions of adverse events and serious adverse events were generally similar between treatment and placebo groups. Four economic evaluations of biologic DMARDs for patients with JIA were identified but all had limitations. Two quality of life studies were included, one of which informed the cost-utility model. The incremental cost-effectiveness ratio (ICER) for adalimumab, etanercept and tocilizumab versus methotrexate was £38,127, £32,526 and £38,656 per QALY, respectively. The ICER for abatacept versus methotrexate as a second line biologic was £39,536 per QALY.Limitations: The model does not incorporate the natural history of JIA in terms of long-term disease progression, as the current evidence is limited. There are no head-to-head trials of biologic DMARDs and clinical evidence for specific JIA subtypes is limited.Conclusions: Biologic DMARDs are superior to placebo (with methotrexate where permitted) in children with (predominantly) polyarticular course JIA, and an insufficient response to previous treatment. Randomised comparisons of biologic DMARDs with long-term efficacy and safety follow- are needed to establish comparative effectiveness. RCTs for JIA subtypes where evidence is lacking are also required.Funding: The National Institute for Health Research Health Technology Assessment programme. <br/