Obesity, asthma, and oxidative stress

Asthma and metabolic syndrome: Current knowledge and future perspectives

Asthma and obesity are epidemiologically linked; however, similar relationships are also observed with other markers of the metabolic syndrome, such as insulin resistance and dyslipidemia, which cannot be accounted for by increased body mass alone. Obesity appears to be a predisposing factor for the asthma onset, both in adults and in children. In addition, obesity could make asthma more difficult to control and to treat. Although obesity may predispose to increased Th2 inflammation or tendency to atopy, other mechanisms need to be considered, such as those mediated by hyperglycaemia, hyperinsulinemia and dyslipidemia in the context of metabolic syndrome. The mechanisms underlying the association between asthma and metabolic syndrome are yet to be determined. In the past, these two conditions were believed to occur in the same individual without any pathogenetic link. However, the improvement in asthma symptoms following weight reduction indicates a causal relationship. The interplay between these two diseases is probably due to a bidirectional interaction. The purpose of this review is to describe the current knowledge about the possible link between metabolic syndrome and asthma, and explore potential application for future studies and strategic approaches.

Proteomic analysis of the asthmatic airway

Proteomic investigations in general utilize varied technologies for sample preparation, separations, quantification, protein identification, and biological rationalization. Their applications range from pure discovery and mechanistic studies to biomarker discovery/verification/validation. In each specific case, the analytical strategy to be implemented is tailored to the type of sample that serves as the target of the investigations. Proteomic investigations take into consideration sample complexity, the cellular heterogeneity (particularly from tissues), the potential dynamic range of the protein and peptide abundance within the sample, the likelihood of posttranslational modifications (PTM), and other important factors that might influence the final output of the study. We describe the sample types typically used for proteomic investigations into the biology of asthma and review the most recent related publications with special attention to those that deal with the unique airway samples such as bronchoalveolar lavage fluids (BALF), epithelial lining fluid and cells (ELF), induced sputum (IS), and exhaled breath condensate (EBC). Finally, we describe the newest proteomics approaches to sample preparation of the unique airway samples, BALF and IS.

Tinospora cordifolia extract modulates COX-2, iNOS, ICAM-1, pro-inflammatory cytokines and redox status in murine model of asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Tinospora cordifolia (Willd.) Miers is an important constituent of several ayurvedic medicinal preparations. In Ayurveda it is mentioned as "rasayan" and traditionally used for the treatment of asthma, chronic cough besides other ailments. This study was carried out to study the mechanisms involved in protection accorded by extract of Tinospora cordifolia (Tc) stem to asthmatic mice by regulation of oxidative stress, pro-inflammatory mediator release and redox signaling involving NFκB.

MATERIALS AND METHODS

BALB/c mice were sensitized with intraperitoneal (i.p.) Ovalbumin (Ova) on days 0 and 14, followed by intranasal Ovalbumin (Ova) challenge on days 24 and 27 to generate an in vivo asthma model. Tc extract (hydroalcoholic, 100 mg/kg) and dexamethasone (1 mg/kg) were given orally from day 15 to 23 to the Tc+Ova treated group and Dex+Ova treated group respectively. Oxidative stress parameters e.g. activity of superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx) and catalase, lipid peroxidation, GSH/GSSG ratio, protein carbonyl content, eosinophil peroxidase, myeloperoxidase activity, and NO release were measured in tissue, blood and bronchoalveolar lavage fluid (BALF). Estimation of cytokines was done in BALF. Western blot analysis was done for IκB α, iNOS, COX-2, iCAM-1 and pJNK MAPKs along with histopathology.

RESULTS

Tc extract treated mice showed decreased airway hyper-responsiveness, eosinophil count and IgE content in blood as compared to Ova treated asthmatic mice. Increase in activities of SOD, catalase, glutathione reductase, glutathione peroxidase as well as GSH/GSSG ratio was observed while a decrease in MDA formation, protein carbonyl content, eosinophil peroxidase, myeloperoxidase activity and NO release in BALF was seen in Tc treated mice. In BALF, levels of cytokines IL-4 and TNF-α were reduced and IFN-γ levels increased in extract treated mice. At the same time Tc treatment of Ova-challenged mice significantly increased the level of IκB α, cytosolic inhibitor of redox sensitive transcription factor NFκB. Immunoblot analysis revealed considerable decrease in the levels of COX-2, ICAM-1, iNOS, and pJNK. Histopathology and PAS staining also indicate a protective effect of Tc extract in inflammation and mucus hyper-secretion due to goblet cell hyperplasia.

CONCLUSION

The results suggest a protective effect of Tc extract against oxidative stress, pro-inflammatory mediator release and redox signaling in the murine model of asthma. The Tc extract shows therapeutic potential for management of asthmatic inflammation and other lung inflammatory conditions.

Poor asthma control in obese children may be overestimated because of enhanced perception of dyspnea

BACKGROUND

Although studies in adults have shown a non-TH2 obese asthma phenotype, whether a similar phenotype exists in children is unclear.

OBJECTIVE

We hypothesized that asthmatic children with obesity, defined as a body mass index above the 95th percentile for age and sex, would have poorer asthma control as well as decreased quality of life, increased health care utilization, and decreased pulmonary function measures as a function of increased TH1 versus TH2 polarization.

METHODS

This study involved a post hoc analysis of cross sectional data from 269 children 6 to 17 years of age enrolled in the National Heart, Lung, and Blood Institute Severe Asthma Research Program. Children answered questionnaires and underwent spirometry, plethysmography, exhaled nitric oxide determination, and venipuncture for TH1/TH2 cytokine determination. Asthma control was defined according to national asthma treatment guidelines that are based on prespecified thresholds for lung function and symptom frequency.

RESULTS

Fifty-eight children (22%) were overweight and 67(25%) were obese. Obese children did not have poorer asthma control but were more likely to report nonspecific symptoms such as dyspnea and nocturnal awakenings. Obese children did have decreased asthma-related quality of life and increased health care utilization, but this was not associated with airflow limitation. Instead, obese children had decreased functional residual capacity. A unique pattern of TH1 or TH2 polarization was not observed.

CONCLUSIONS

Poor asthma control in obese children with asthma may be overestimated because of enhanced perception of nonspecific symptoms such as dyspnea that results from altered mechanical properties of the chest wall. Careful assessment of physiologic as well as symptom-based measures is needed in the evaluation of obese children with respiratory symptoms.

Engineered silica nanoparticles act as adjuvants to enhance allergic airway disease in mice

Background

With the increase in production and use of engineered nanoparticles (NP; ≤ 100 nm), safety concerns have risen about the potential health effects of occupational or environmental NP exposure. Results of animal toxicology studies suggest that inhalation of NP may cause pulmonary injury with subsequent acute or chronic inflammation. People with chronic respiratory diseases like asthma or allergic rhinitis may be even more susceptible to toxic effects of inhaled NP. Few studies, however, have investigated adverse effects of inhaled NP that may enhance the development of allergic airway disease.

Methods

We investigated the potential of polyethylene glycol coated amorphous silica NP (SNP; 90 nm diameter) to promote allergic airway disease when co-exposed during sensitization with an allergen. BALB/c mice were sensitized by intranasal instillation with 0.02% ovalbumin (OVA; allergen) or saline (control), and co-exposed to 0, 10, 100, or 400 μg of SNP. OVA-sensitized mice were then challenged intranasally with 0.5% OVA 14 and 15 days after sensitization, and all animals were sacrificed a day after the last OVA challenge. Blood and bronchoalveolar lavage fluid (BALF) were collected, and pulmonary tissue was processed for histopathology and biochemical and molecular analyses.

Results

Co-exposure to SNP during OVA sensitization caused a dose-dependent enhancement of allergic airway disease upon challenge with OVA alone. This adjuvant-like effect was manifested by significantly greater OVA-specific serum IgE, airway eosinophil infiltration, mucous cell metaplasia, and Th2 and Th17 cytokine gene and protein expression, as compared to mice that were sensitized to OVA without SNP. In saline controls, SNP exposure did cause a moderate increase in airway neutrophils at the highest doses.

Conclusions

These results suggest that airway exposure to engineered SNP could enhance allergen sensitization and foster greater manifestation of allergic airway disease upon secondary allergen exposures. Whereas SNP caused innate immune responses at high doses in non-allergic mice, the adjuvant effects of SNP were found at lower doses in allergic mice and were Th2/Th17 related. In conclusion, these findings in mice suggest that individuals exposed to SNP might be more prone to manifest allergic airway disease, due to adjuvant-like properties of SNP.

Lung age in women with morbid obesity

OBJECTIVE

To investigate the influence of morbid obesity on the lung age in women and to correlate with body mass, body mass index (BMI), and ventilatory variables.

METHODS

This was a cross-sectional study with 72 morbidly obese women and a control group consisting of 37 normal weight women. The subjects performed a pulmonary function test to determine lung age, and the results were correlated to anthropometric variables and lung volumes.

RESULTS

The morbidly obese group had significantly higher lung age (50.1±6.8 years) than the control group (38.8±11.4 years). There was no difference in chronological age between groups. There was a significant positive correlation among chronological age, body mass, BMI, and lung age (r=0.3647, 0.4182, and 0.3743, respectively). There was a negative correlation among forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC ratio, expiratory reserve volume (ERV), and lung age (r=-0.7565, -0.8769, --0.2723, and -0.2417, respectively).

CONCLUSION

Lung age is increased in morbidly obese women and is associated with increased body mass and BMI.

Obesity and asthma: a coincidence or a causal relationship? A systematic review

BACKGROUND AND AIM

Epidemiological data has established increasing adiposity as a risk factor for incident asthma. However, the mechanisms underlying the association between obesity and asthma are incompletely understood. In the present paper, we review current knowledge of possible mechanisms mediating the observed association between obesity and asthma.

METHODS

Systematic literature review.

RESULTS

Obesity and asthma share some etiological factors, such as a common genetic predisposition and effects of in utero conditions, and may also have common predisposing factors such as physical activity and diet. Obesity results in important changes in the mechanical properties of the respiratory system which could explain the occurrence of asthma. However, there are also plausible biological mechanisms whereby obesity could be expected to either cause or worsen asthma. These include co-morbidities such as gastro-oesophageal reflux, complications from sleep-disordered breathing, breathing at low lung volumes, chronic systemic inflammation, and endocrine factors, including adipokines and reproductive hormones. Obesity related asthma is in general not associated with eosinophilic airway inflammation, and adipokines are likely to play important roles in the inflammatory pathogenesis of asthma in obese individuals.

CONCLUSION

The association between obesity and asthma is not straightforward, and further knowledge is clearly needed, as understanding the underlying mechanisms may lead to new therapeutic options for this high-risk part of the asthma population.

Role of obesity in asthma control, the obesity-asthma phenotype

Asthma is a disease with distinct phenotypes that have implications for both prognosis and therapy. Epidemiologic studies have demonstrated an association between asthma and obesity. Further studies have shown that obese asthmatics have poor asthma control and more severe asthma. This obese-asthma group may represent a unique phenotype. The mechanisms behind poor asthma control in obese subjects remain unclear, but recent research has focused on adipokines and their effects on the airways as well as the role of oxidative stress. Both surgical and nonsurgical weight loss therapy have shown promising results with improvements in asthma control and decreased asthma severity. Comorbid conditions such as gastroesophageal reflux disease and obstructive sleep apnea may also have a role in poor asthma control in obese asthmatics. Further research is needed to define the mechanisms behind this phenotype which will guide the development of targeted therapies.

Arginine and nitric oxide pathways in obesity-associated asthma

Obesity is a comorbidity that adversely affects asthma severity and control by mechanisms that are not fully understood. This review will discuss evidence supporting a role for nitric oxide (NO) as a potential mechanistic link between obesity and late-onset asthma (>12 years). Several studies have shown that there is an inverse association between increasing body mass index (BMI) and reduced exhaled NO. Newer evidence suggests that a potential explanation for this paradoxical relationship is related to nitric oxide synthase (NOS) uncoupling, which occurs due to an imbalance between L-arginine (NOS substrate) and its endogenous inhibitor, asymmetric di-methyl arginine (ADMA). The review will propose a theoretical framework to understand the relevance of this pathway and how it may differ between early and late-onset obese asthmatics. Finally, the paper will discuss potential new therapeutic approaches, based on these paradigms, for improving the respiratory health of obese subjects with asthma.

Controlled exposure to diesel exhaust causes increased nitrite in exhaled breath condensate among subjects with asthma

OBJECTIVE

To determine whether oxidative/nitrosative stress plays a role in the acute effects of diesel exhaust (DE) on subjects with asthma.

METHODS

In this crossover study, 16 subjects with mild to moderate asthma were exposed to clean filtered air or diluted DE (300 μg/m as PM2.5) for 1 hour with intermittent exercise.

RESULTS

Airway hyperreactivity increased 24 hours after exposure to DE compared with clean filtered air (PC20, 14.9 mg/mL vs 19.7 mg/mL; P = 0.012). Nitrite in exhaled breath condensate was elevated immediately after diesel exposure (P = 0.052) and remained elevated 4 and 24 hours after exposure.

CONCLUSIONS

After exposure to DE, subjects with asthma demonstrated increased airway hyperreactivity and obstruction. Increased nitrite in exhaled breath condensate, in the absence of increased exhaled nitric oxide, suggests a noninflammatory oxidative stress mechanism by which DE affects the lung.

Assessing the relationship between obesity and asthma in adolescent patients: a review

The parallel rise in the prevalence of obesity and asthma over the last several decades has led to an extensive line of investigation into the relationship between these two conditions. This review will discuss evidence from laboratory-based studies, observational clinical studies, and clinical trials that suggests that obesity adversely influences asthma through multiple mechanisms. The effect of obesity on asthma during adolescence, including asthma incidence, the severity and control of existing asthma, lung function, and exacerbations, will be reviewed.

Being overweight increases susceptibility to indoor pollutants among urban children with asthma

BACKGROUND

Both being overweight and exposure to indoor pollutants, which have been associated with worse health of asthmatic patients, are common in urban minority populations. Whether being overweight is a risk factor for the effects of indoor pollutant exposure on asthma health is unknown.

OBJECTIVES

We sought to examine the effect of weight on the relationship between indoor pollutant exposure and asthma health in urban minority children.

METHODS

One hundred forty-eight children (age, 5-17 years) with persistent asthma were followed for 1 year. Asthma symptoms, health care use, lung function, pulmonary inflammation, and indoor pollutants were assessed every 3 months. Weight category was based on body mass index percentile.

RESULTS

Participants were predominantly African American (91%) and had public health insurance (85%). Four percent were underweight, 52% were normal weight, 16% were overweight, and 28% were obese. Overweight or obese participants had more symptoms associated with exposure to fine particulate matter measuring less than 2.5 μm in diameter (PM2.5) than normal-weight participants across a range of asthma symptoms. Overweight or obese participants also had more asthma symptoms associated with nitrogen dioxide (NO2) exposure than normal-weight participants, although this was not observed across all types of asthma symptoms. Weight did not affect the relationship between exposure to coarse particulate matter measuring between 2.5 and 10 μm in diameter and asthma symptoms. Relationships between indoor pollutant exposure and health care use, lung function, or pulmonary inflammation did not differ by weight.

CONCLUSION

Being overweight or obese can increase susceptibility to indoor PM2.5 and NO2 in urban children with asthma. Interventions aimed at weight loss might reduce asthma symptom responses to PM2.5 and NO2, and interventions aimed at reducing indoor pollutant levels might be particularly beneficial in overweight children.

Review on the impact of pregnancy and obesity on influenza virus infection

A myriad of risk factors have been linked to an increase in the severity of the pandemic H1N1 2009 influenza A virus [A(H1N1)pdm09] including pregnancy and obesity where death rates can be elevated as compared to the general population. The goal of this review is to provide an overview of the influence of pregnancy and obesity on the reported cases of A(H1N1)pdm09 virus infection and of how the concurrent presence of these factors may have an exacerbating effect on infection outcome. Also, the hypothesized immunologic mechanisms that contribute to A(H1N1)pdm09 virus severity during pregnant or obese states are outlined. Identifying the mechanisms underlying the increased disease severity in these populations may result in improved therapeutic approaches and future pandemic preparedness.

Biomarkers in asthma: a real hope to better manage asthma

Diagnosis and treatment of asthma are currently based on assessment of patient symptoms and physiologic tests of airway reactivity. Research over the past decade has identified an array of biochemical and cellular biomarkers, which reflect the heterogeneous and multiple mechanistic pathways that may lead to asthma. These mechanistic biomarkers offer hope for optimal design of therapies targeting the specific pathways that lead to inflammation. This article provides an overview of blood, urine, and airway biomarkers; summarizes the pathologic pathways that they signify; and begins to describe the utility of biomarkers in the future care of patients with asthma.

Obesity and pulmonary disease: unanswered questions

Obesity is associated with risk of pulmonary disease, and adversely affects lung function. The parallel increase in obesity and asthma suggests the two conditions are linked; indeed, they can worsen each other. Obesity and inadequate asthma control are associated with poor quality of life, and place a high economic burden on public health. Although the obesity-lung interaction is a major issue for basic research and clinical studies, various questions remain unanswered. Do intrauterine and early life factors impact on the development of obesity and lung disease? If so, can this be prevented? Asthma is generally more severe in obese subjects, but is adiposity a driver of a new asthma phenotype that features greater morbidity and mortality, worse control and decreased response to medications? Obese individuals have small lung volumes, hence their airway calibre is reduced and airway resistance is increased. What puzzles physicians is whether peripheral airways undergo remodelling, which would increase bronchoconstriction. Obese asthmatics respond suboptimally to anti-inflammatory treatment, which raises the question: 'what drug for what patient?' Life expectancy is decreased in obesity and in chronic pulmonary disorders, but does obesity protect against or trigger chronic obstructive pulmonary disease? The time has come to find answers to these questions.

Obesity and asthma disease phenotypes

PURPOSE OF REVIEW

The increasing prevalence of both asthma and obesity is associated with substantial morbidity and healthcare utilization. Herein, we review recent data suggesting that the obese asthmatic may represent a distinct clinical phenotype.

RECENT FINDINGS

Obesity is a major risk factor for asthma, and asthma in obese patients appears to be more difficult to control, with decreased responsiveness to controller therapies posing a significant public health issue, as the prevalence of both asthma and obesity continues to rise. Epidemiologic research has defined the association between obesity and asthma, an association in part influenced by physiologic abnormalities attendant to both disorders. Healthcare utilization is also increased in obese asthmatic individuals, with reduced response to asthma controller therapies, a finding likely mediated by specific aspects of systemic and airway inflammation. We end by reviewing the role of comorbid clinical disorders in the association and by highlighting evidence that weight loss is associated with improvement in clinical and physiologic parameters of asthma.

SUMMARY

Obesity has a significant impact on asthma risk, severity and control. Additional studies are needed to define mechanisms by which airway physiologic and inflammatory phenotypes in asthma are modified by obesity.

Severe asthma: lessons learned from the National Heart, Lung, and Blood Institute Severe Asthma Research Program

The National Heart, Lung, and Blood Institute Severe Asthma Research Program (SARP) has characterized over the past 10 years 1,644 patients with asthma, including 583 individuals with severe asthma. SARP collaboration has led to a rapid recruitment of subjects and efficient sharing of samples among participating sites to conduct independent mechanistic investigations of severe asthma. Enrolled SARP subjects underwent detailed clinical, physiologic, genomic, and radiological evaluations. In addition, SARP investigators developed safe procedures for bronchoscopy in participants with asthma, including those with severe disease. SARP studies revealed that severe asthma is a heterogeneous disease with varying molecular, biochemical, and cellular inflammatory features and unique structure-function abnormalities. Priorities for future studies include recruitment of a larger number of subjects with severe asthma, including children, to allow further characterization of anatomic, physiologic, biochemical, and genetic factors related to severe disease in a longitudinal assessment to identify factors that modulate the natural history of severe asthma and provide mechanistic rationale for management strategies.

Obesity, metabolic dysregulation and oxidative stress in asthma

BACKGROUND

Epidemiological data demonstrate an increased risk of developing incident asthma with increasing adiposity. While the vast majority of studies support the interaction between obesity and asthma, the causality is unclear.

SCOPE OF REVIEW

This article will review the current literature supporting the presence of an obese asthma phenotype and the possible mechanisms mediating the effects of obesity on asthma.

MAJOR CONCLUSIONS

Obesity is associated with poor asthma control, altered responsiveness to medications and increased morbidity. Obesity is characterized by systemic inflammation that may result in increased airway inflammation. However, this assertion is not supported by current studies that demonstrate a lack of significant airway inflammation in obese asthmatics. In spite this observation one must consider limitations of these studies including the fact that most subjects were treated with inhaled corticosteroids that would likely alter inflammation in the lung. Thus, it remains unclear if obesity is associated with alterations in inflammation in the airways of subjects with asthma. Hormones such as leptin and adiponectin are affected by obesity and may play a role in mediating innate immune responses and allergic responses, respectively. The role of oxidative stress remains controversial and the current evidence suggests that while oxidative stress is important in asthma, it does not fully explain the characteristics associated with this unique phenotype.

GENERAL SIGNIFICANCE

Obesity related asthma is associated with increased morbidity and differential response to asthma therapies. Understanding the mechanisms mediating this phenotype would have significant implications for millions of people suffering with asthma. This article is part of a Special Issue entitled Biochemistry of Asthma.

Novel Conjugates of 1,3-Diacylglycerol and Lipoic Acid: Synthesis, DPPH Assay, and RP-LC-MS-APCI Analysis

1,3-Diacylglycerol is known to reduce body weight and fat deposits in humans. α-Lipoic acid is a potent antioxidant and effective against many pathological conditions, including obesity and related metabolic syndromes. The present work is based on the hypothesis that the hybrid molecules of 1,3-diacylglycerol and lipoic acid possess synergistic and/or additive effects compared with the parent compounds against obesity, overweight, and related metabolic syndromes. Laboratory scale synthesis of 1,3-dioleoyl-2-lipoyl-sn-glycerol (yield 80%) and 1,3-dioleoyl-2-dihydrolipoyl-sn-glycerol (yield 70%) was performed for the first time and supported by NMR and MS data. Free radical scavenging capacity of the conjugates was assayed using DPPH test. A remarkably high in vitro free radical scavenging capacity was demonstrated for the 1,3-dioleoyl-2-dihydrolipoyl-sn-glycerol (EC(50) value 0.21). RP-HPLC-MS-APCI analysis showed satisfactory separation between the conjugates (R~1). Protonated molecular ion of the conjugates at m/z 809 and m/z at 811, respectively, and their characteristic fragment ions were abundant.

Nitric oxide metabolism in asthma pathophysiology

BACKGROUND

Asthma, a chronic inflammatory disease is typically characterized by bronchoconstriction and airway hyper-reactivity.

SCOPE OF REVIEW

A wealth of studies applying chemistry, molecular and cell biology to animal model systems and human asthma over the last decade has revealed that asthma is associated with increased synthesis of the gaseous molecule nitric oxide (NO).

MAJOR CONCLUSION

The high NO levels in the oxidative environment of the asthmatic airway lead to greater formation of reactive nitrogen species (RNS) and subsequent oxidation and nitration of proteins, which adversely affect protein functions that are biologically relevant to chronic inflammation. In contrast to the high levels of NO and nitrated products, there are lower levels of beneficial S-nitrosothiols (RSNO), which mediate bronchodilation, due to greater enzymatic catabolism of RSNO in the asthmatic airways.

GENERAL SIGNIFICANCE

This review discusses the rapidly accruing data linking metabolic products of NO as critical determinants in the chronic inflammation and airway reactivity of asthma. This article is part of a Special Issue entitled Biochemistry of Asthma.

Nontraditional risk factors and biomarkers for cardiovascular disease: mechanistic, research, and clinical considerations for youth: a scientific statement from the American Heart Association

The rapid increase in the prevalence and severity of obesity in children is likely to lower the age of onset and increase the incidence of cardiovascular disease worldwide. Understanding the pathophysiology and improving the clinical management of cardiovascular disease involve a knowledge of novel risk factors and biomarkers. The clinical and mechanistic roles of these novel biological factors during childhood are currently being investigated. The goals of this scientific statement are to present the existing knowledge and theoretical framework of nontraditional risk factors for cardiovascular disease as they relate to children and adolescents, to describe the relevance and weight of available experimental and clinical evidence and the therapeutic implications pertaining to nontraditional risk factors in the pediatric population, and to stimulate further research with a goal of developing valid and reliable approaches to identify and validate novel risk factors that will aid in the clinical evaluation and perhaps prediction of cardiovascular disease in the pediatric population. Although several biomarkers are promising, substantial research is required before nontraditional risk factors can be used to identify and reduce cardiovascular disease risk in children and adolescents.

Eight weeks of conjugated linoleic acid supplementation has no effect on antioxidant status in healthy overweight/obese Korean individuals

PURPOSE

The aim of this study was to evaluate the effect of CLA supplementation on antioxidant metabolism in healthy overweight/obese Korean individuals.

METHODS

We performed a randomized, double-blind, placebo-controlled trial, where 29 healthy overweight/obese (BMI ≥ 23 kg/m(2)) participants (2 men and 27 women) were randomly selected to receive placebo (n = 15, 2.4 g olive oil/day) or 2.4 g/day CLA mixture (n = 14, 36.9% of cis-9, trans-11 and 37.9% of trans-10, cis-12) for 8 weeks.

RESULTS

There were no significant differences in plasma total radical-trapping antioxidant potential (TRAP), lipid peroxidation (conjugated dienes), lipid-soluble antioxidant vitamin concentration, erythrocyte antioxidant enzyme (superoxide dismutase, catalase, glutathione peroxidase) activities, and leukocyte DNA damage between the CLA and placebo groups.

CONCLUSIONS

The data suggest that short-term supplementation (8 weeks) with CLA (2.4 g/day) might have no significant effects on lipid peroxidation and antioxidant metabolism.

ALOX12 polymorphisms are associated with fat mass but not peak bone mineral density in Chinese nuclear families

OBJECTIVE

Arachidonate 12-lipoxygenase (ALOX12) is a member of the lipoxygenase superfamily, which catalyzes the incorporation of molecular oxygen into polyunsaturated fatty acids. The products of ALOX12 reactions serve as endogenous ligands for peroxisome proliferator-activated receptor γ (PPARG). The activation of the PPARG pathway in marrow-derived mesenchymal progenitors stimulates adipogenesis and inhibits osteoblastogenesis. Our objective was to determine whether polymorphisms in the ALOX12 gene were associated with variations in peak bone mineral density (BMD) and obesity phenotypes in young Chinese men.

METHODS

All six tagging single-nucleotide polymorphisms (SNPs) in the ALOX12 gene were genotyped in a total of 1215 subjects from 400 Chinese nuclear families by allele-specific polymerase chain reaction. The BMD at the lumbar spine and hip, total fat mass (TFM) and total lean mass (TLM) were measured using dual-energy X-ray absorptiometry. The pairwise linkage disequilibrium among SNPs was measured, and the haplotype blocks were inferred. Both the individual SNP markers and the haplotypes were tested for an association with the peak BMD, body mass index, TFM, TLM and percentage fat mass (PFM) using the quantitative transmission disequilibrium test (QTDT).

RESULTS

Using the QTDT, significant within-family association was found between the rs2073438 polymorphism in the ALOX12 gene and the TFM and PFM (P=0.007 and 0.012, respectively). Haplotype analyses were combined with our individual SNP results and remained significant even after correction for multiple testing. However, we failed to find significant within-family associations between ALOX12 SNPs and the BMD at any bone site in young Chinese men.

CONCLUSIONS

Our present results suggest that the rs2073438 polymorphism of ALOX12 contributes to the variation of obesity phenotypes in young Chinese men, although we failed to replicate the association with the peak BMD variation in this sample. Further independent studies are needed to confirm our findings.