Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

Microarray profiling of human white adipose tissue after exogenous leptin injection

BACKGROUND: Leptin is a secreted adipocyte hormone that plays a key role in the regulation of body weight homeostasis. The leptin effect on human white adipose tissue (WAT) is still debated. OBJECTIVE: The aim of this study was to assess whether the administration of polyethylene glycol-leptin (PEG-OB) in a single supraphysiological dose has transcriptional effects on genes of WAT and to identify its target genes and functional pathways in WAT. MATERIALS AND METHODS: Blood samples and WAT biopsies were obtained from 10 healthy nonobese men before treatment and 72 h after the PEG-OB injection, leading to an approximate 809-fold increase in circulating leptin. The WAT gene expression profile before and after the PEG-OB injection was compared using pangenomic microarrays. Functional gene annotations based on the gene ontology of the PEG-OB regulated genes were performed using both an 'in house' automated procedure and GenMAPP (Gene Microarray Pathway Profiler), designed for viewing and analyzing gene expression data in the context of biological pathways. RESULTS: Statistical analysis of microarray data revealed that PEG-OB had a major down-regulated effect on WAT gene expression, as we obtained 1,822 and 100 down- and up-regulated genes, respectively. Microarray data were validated using reverse transcription quantitative PCR. Functional gene annotations of PEG-OB regulated genes revealed that the functional class related to immunity and inflammation was among the most mobilized PEG-OB pathway in WAT. These genes are mainly expressed in the cell of the stroma vascular fraction in comparison with adipocytes. CONCLUSION: Our observations support the hypothesis that leptin could act on WAT, particularly on genes related to inflammation and immunity, which may suggest a novel leptin target pathway in human WA

Effect of dietary restraint during and following pegylated recombinant leptin (PEG-OB) treatment of overweight men

Effect of dietary restraint during and following pegylated recombinant leptin (PEG-OB) treatment of overweight men. Lejeune MP, Hukshorn CJ, Saris WH, Westerterp-Plantenga MS. Department of Human Biology, Maastricht University, Maastricht, The Netherlands. [email protected] OBJECTIVE: To examine the effect of dietary restraint during and following pegylated recombinant leptin (PEG-OB protein) treatment in overweight men. DESIGN: A randomized double-blind placebo-controlled trial in 24 overweight men (BMI: 28.8+/-0.3 kg/m(2); age: 34.8+/-0.9 y). PEG-OB protein (80 mg) or placebo was administered subcutaneously weekly for 6 weeks, combined with a 2.1 MJ/day energy restriction program. Dietary restraint was determined by the Three-Factor Eating Questionnaire before and after treatment, and after 8 weeks follow-up. RESULTS: During treatment dietary restraint increased, and general hunger, resting energy expenditure and respiratory quotient decreased similarly in the PEG-OB and the placebo group. With PEG-OB treatment, additional weight loss (P<0.03) was observed. During 8 weeks follow-up, body weight increase was larger in the PEG-OB group compared to placebo (P<0.05), and body weight regain was faster. Body weight regain was inversely correlated with the increase in cognitive dietary restraint during treatment (PEG-OB group: r(2)=0.49, P<0.02; placebo group: r(2)=0.60, P=0.01). CONCLUSION: Although treatment with PEG-OB protein led to a greater body weight loss relative to placebo, weight maintenance thereafter was mainly supported by dietary restraint, which was more effective in the placebo-treated group, resulting in a slower regain of body weight

The effect of pegylated recombinant human leptin (PEG-OB) on weight loss and inflammatory status in obese subjects

The effect of pegylated recombinant human leptin (PEG-OB) on weight loss and inflammatory status in obese subjects. Hukshorn CJ, van Dielen FM, Buurman WA, Westerterp-Plantenga MS, Campfield LA, Saris WH. Nutrition and Toxicology Research Institute Maastricht, Department of Human Biology, Maastricht University, The Netherlands. [email protected] OBJECTIVE: To investigate whether weekly subcutaneous administration of 60 mg of long-acting pegylated human leptin (PEG-OB) for 8 weeks was able to influence weight loss, metabolic profile and inflammatory status of obese subjects on a mildly hypoenergetic diet (deficit: 3.2 MJ/day). DESIGN: A prospective, randomized, double-blind and placebo-controlled single-center trial. SUBJECTS: Twenty-eight healthy, obese subjects (16 women, 12 men; age 22-65 y; body mass index 27.7-38.7 kg/m2). MEASUREMENTS: Bodyweight, metabolic profile (including lipids), C-reactive protein (CRP) and soluble TNF alpha-receptor (sTNF-R) 55 and 75 levels. RESULTS: At the end of the study no significant differences in the delta or percentage weight loss between the placebo (n = 14) and PEG-OB (n = 14) groups was observed. Also the changes in metabolic profile, CRP, sTNF-R55 and R75 concentrations between the two groups after 8 weeks of treatment did not differ. CONCLUSION: Weekly injection of 60 mg PEG-OB did not lead to additional weight loss after 8 weeks of treatment. Furthermore, PEG-OB administration did not affect the changes in metabolic profile and the inflammatory status of obese subjects