Beta(2)-adrenoceptor polymorphism and body mass index are associated with adult-onset asthma in sedentary but not active women

Association Between Asthma and All-Cause Mortality and Cardiovascular Disease Morbidity and Mortality: A Meta-Analysis of Cohort Studies

Background

Asthma and cardiovascular disease (CVD) share many risk factors. Previous meta-analyses indicated that asthma is associated with an increased risk of CVD and all-cause mortality, but these studies were limited by unstandardized search strategies and the number of articles included.

Objective

We sought to systematically synthesize evidence investigating the impact of asthma on all-cause mortality and CVD morbidity and mortality.

Methods

We searched in PubMed and EMBASE for observational cohort studies (inception dates to November 10, 2021) that had both asthma groups and control groups. We also manually searched the reference lists of correlative articles to include other eligible studies. Data for associations between asthma and all-cause mortality and CVD morbidity and mortality were needed.

Results

We summarized the findings from 30 cohort studies comprising 4,157,823 participants. Asthma patients had increased CVD morbidity [relative risk (RR) = 1.28, 95% confidence interval (CI) = 1.16–1.40] and increased CVD mortality (RR = 1.25, 95% CI = 1.14–1.38). Asthma patients also had increased risk of all-cause mortality (RR = 1.38, 95% CI = 1.07–1.77). In subgroup analyses, female asthma patients had a higher risk of CVD morbidity and all-cause mortality than male asthma patients, and late-onset asthma patients had a higher risk of CVD morbidity than early-onset asthma patients.

Conclusion

Asthma patients have increased risk of all-cause mortality and CVD morbidity and mortality. This information reminds clinicians to be aware of the risk of CVD and all-cause mortality in asthma patients.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, PROSPERO, identifier: CRD 42021290082.

Benefits of physical activity on COPD hospitalisation depend on intensity

The present study aims to disentangle the independent effects of the quantity and the intensity of physical activity on the risk reduction of chronic obstructive pulmonary disease (COPD) hospitalisations.177 patients from the Phenotype Characterization and Course of COPD (PAC-COPD) cohort (mean±sd age 71±8 years, forced expiratory volume in 1 s 52±16% predicted) wore the SenseWear Pro 2 Armband accelerometer (BodyMedia, Pittsburgh, PA, USA) for eight consecutive days, providing data on quantity (steps per day, physically active days and daily active time) and intensity (average metabolic equivalent tasks) of physical activity. Information on COPD hospitalisations during follow-up (2.5±0.8 years) was obtained from validated centralised datasets. During follow-up 67 (38%) patients were hospitalised. There was an interaction between quantity and intensity of physical activity in their effects on COPD hospitalisation risk. After adjusting for potential confounders in the Cox regression model, the risk of COPD hospitalisation was reduced by 20% (hazard ratio (HR) 0.79, 95% CI 0.67-0.93; p=0.005) for every additional 1000 daily steps at low average intensity. A greater quantity of daily steps at high average intensity did not influence the risk of COPD hospitalisations (HR 1.01, p=0.919). Similar results were found for the other measures of quantity of physical activity. Greater quantity of low-intensity physical activity reduces the risk of COPD hospitalisation, but high-intensity physical activity does not produce any risk reduction.

Association between β2-adrenoceptor gene polymorphisms and asthma risk: an updated meta-analysis

Background

Evidence is increasingly accumulated about multiple roles for the β2-adrenoceptor gene in asthma. The results were inconsistent partly due to small sample sizes. To assess the association between β2-adrenoceptor gene polymorphisms and asthma risk, a meta-analysis was performed.

Methods

We comprehensively searched the PubMed, EMBASE, BIOSIS Previews databases and extracted data from all eligible articles to estimate the association between β2-adrenoceptor gene polymorphisms and asthma risk. The pooled odds ratio (OR) with 95% confidence intervals (CIs) were calculated.

Results

Thirty-seven studies involving 6648 asthma patients and 15943 controls were included in the meta-analysis. Overall, significant associations were found in allelic genetic model (OR = 1.06, 95% CI = 1.01∼1.12), recessive genetic model (OR = 1.11, 95% CI = 1.02∼1.21) for Arg/Gly16. Stratified by ethnicity and age, significant associations were also found in Asian population in allelic genetic model, recessive genetic model and addictive model. For Gln/Glu27, no significant association was found when we combined all eligible studies. Age stratification showed significant associations in adults in allelic genetic model and recessive genetic model, but no significant association was found among Asians and Caucasians in ethnicity stratification.

Conclusions

This meta-analysis implied that the β2-adrenoceptor Arg/Gly16 polymorphism was likely to contribute to asthma risk in Asian population. Gln/Glu27 polymorphism might be a contributor to asthma susceptibility for adults.

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.

Prognostic value of the objective measurement of daily physical activity in patients with COPD

BACKGROUND

Subjective measurement of physical activity using questionnaires has prognostic value in COPD. However, their lack of accuracy and large individual variability limit their use for evaluation on an individual basis. We evaluated the capacity of the objective measurement of daily physical activity in patients with COPD using accelerometers to estimate their prognostic value.

METHODS

In 173 consecutive subjects with moderate to very severe COPD, daily physical activity was measured using a triaxial accelerometer providing a mean of 1-min movement epochs as vector magnitude units (VMUs). Patients were evaluated by lung function testing and 6-min walk, incremental exercise, and constant work rate tests. Patients were followed for 5 to 8 years, and the end points were all-cause mortality, hospitalization for COPD exacerbation, and annual declining FEV(1).

RESULTS

After adjusting for relevant confounders, a high VMU decreased the mortality risk (adjusted hazard ratio [HR], 0.986; 95% CI, 0.981-0.992), and in a multivariate model, comorbidity, endurance time, and VMU were retained as independent predictors of mortality. The time until first admission due to COPD exacerbation was shorter for the patients with lower levels of VMU (adjusted HR, 0.989; 95% CI, 0.983-0.995). Moreover, patients with higher VMU had a lower hospitalization risk than those with a low VMU (adjusted incidence rate ratio, 0.099; 95% CI, 0.033-0.293). In contrast, VMU was not identified as an independent predictor of the annual FEV(1) decline.

CONCLUSION

The objective measurement of the daily physical activity in patients with COPD using an accelerometer constitutes an independent prognostic factor for mortality and hospitalization due to severe exacerbation.

Body mass index and acute asthma severity among children presenting to the emergency department

To determine the prevalence of obesity among children presenting to the emergency department (ED) with acute asthma, and to examine the relationship between body mass index (BMI) and acute asthma severity in the ED setting. We analyzed data from a multicenter prospective cohort study during 1997-1998; 44 ED in 17 US states and two Canadian provinces enrolled 672 patients, age 5-17, with acute asthma. BMI and Pulmonary Index were collected in the ED. We defined overweight and obesity using age, sex, and race-specific BMI values from national and international databases. The prevalence of obesity was significantly higher among ED patients with acute asthma as compared with children from the general population (23% vs. 9-15%; p < 0.001). Obese children with acute asthma did not differ from their non-obese counterparts, by demographic factors or chronic asthma severity (all p > 0.2). Initial Pulmonary Index was the same across underweight, intermediate, and obese groups (3.7 +/- 2.4, 3.8 +/- 2.2, 3.7 +/- 2.3; p = 0.70). Admission status also did not vary across groups (22%, 22% and 23%; p = 0.98). Stratifying the analysis by age group and sex did not change these results. The prevalence of obesity among children presenting to the ED with acute asthma was significantly higher compared with children from the general population. BMI was not associated with markers of chronic and acute asthma severity. The results of this study support a positive association between obesity and asthma, and suggest that asthma exacerbations among obese children are very similar to those experienced by other children.

Pharmaceutical treatment strategies for childhood asthma

PURPOSE OF REVIEW

Although great improvement has been obtained in quality of life and mastering of illness by asthmatic children over recent decades, controversies still exist related to asthma treatment. The objective of the present article is to discuss such controversies.

RECENT FINDINGS

Results from recent publications related to childhood asthma treatment question existing dogmas. Important for prescribing correct treatment to children is correct diagnosis. Phenotypes of childhood asthma related to treatment decisions are discussed. Early use of inhaled steroids in young children is still debated as well as the preference of inhaled long-acting beta2-agonists versus leukotriene receptor antagonists as add on to inhaled steroids. When present, both allergic rhinitis and asthma should be treated to obtain improved control. Also as regards the treatment of exercise-induced asthma in children, new results concerning use of leukotriene receptor antagonists is discussed as well as the acute treatment in infants with bronchial obstruction.

SUMMARY

There are still several controversies regarding treatment of the asthmatic child. New studies designed specifically for children are needed to solve these questions. One cannot rely on studies performed in adults for treatment in children. New studies designed for childhood asthma are needed to solve these controversies.

An interdisciplinary analysis of sex and gender in relation to the pathogenesis of bronchial asthma

BACKGROUND

An increasing number of studies confirm that pathogenesis and prevalence of bronchial asthma are age and sex dependent. Detailed physiological mechanisms of the changing sex ratios with age are not fully known, however, the gender (socio-cultural) factors are also imperative. Although multiple factors definitely influence the pathogenesis of asthma, only individual or few combinations of these have been investigated.

METHODS

The terms 'sex', 'gender' and plausible combinations of both were systematically researched in selected databases (Medline, Scopus) or other sources, including publications from January 2000 to June 2007. Generated articles were categorized, either as endogenous or exogenous factors influencing the pathogenesis of asthma, and divided into the following subgroups: genetic, immunological, hormonal, gynaecological, nutritional, and environmental parameters.

RESULTS

An increasing number of studies investigate the influence of sex and gender in the aetiology, therapy and prevention of asthma. While their results are still debatable, others regarding its initiation, perpetuation and cessation have been clarified. Recent insights into interactions at biomolecular and immunological levels greatly contribute to clarifying sex-specific influences. Despite occasional oversimplifications, a trend for explanations considering the complex interplay of different factors can be observed. This work is in line with this trend and offers explanation models from our point of view.

CONCLUSIONS

Some disagreements regarding the patho-physiology, diagnosis, treatment and prevention of asthma still prevail. Nevertheless, in order to better appreciate its complexity, openness to and persistent consideration for interdisciplinary as well as sex- and gender-related factors is required of the medical-research community in future investigations.

Environmental epigenetics and asthma: current concepts and call for studies

Recent studies suggest that epigenetic regulation (heritable changes in gene expression that occur in the absence of alterations in DNA sequences) may in part mediate the complex gene-by-environment interactions that can lead to asthma. The variable natural history of asthma (i.e., incidence and remission of symptoms) may be a result of epigenetic changes, such as DNA methylation, covalent histone modifications, microRNA changes, and chromatin alterations, after early or later environmental exposures. Findings from multiple epidemiologic and experimental studies indicate that asthma risk may be modified by epigenetic regulation. One study suggested that the transmission of asthma risk may occur across multiple generations. Experimental studies provide substantial in vitro data indicating that DNA methylation of genes critical to T-helper cell differentiation may induce polarization toward or away from an allergic phenotype. Despite this initial progress, fundamental questions remain that need to be addressed by well-designed research studies. Data generated from controlled experiments using in vivo models and/or clinical specimens collected after environmental exposure monitoring are limited. Importantly, cohort-driven epigenetic research has the potential to address key questions, such as those concerning the influence of timing of exposure, dose of exposure, diet, and ethnicity on susceptibility to asthma development. There is immense promise that the study of environmental epigenetics will help us understand a theoretically preventable environmental disease.

Gene by environment interaction in asthma

Asthma is a chronic inflammatory disease of the airways that is highly prevalent in the Western world. It is a genetically complex disease caused by multiple genetic and environmental factors, which may interact. Genetic research has recently incorporated environmental factors to investigate gene by environment interaction, and the first examples of gene by environment interaction in asthma have been reported. Linkage analyses indicate that one or more genes on chromosome 5q interact with environmental tobacco smoke in infancy in asthma development. Several candidate genes have been consistently shown to interact with the environment. These include the innate immunity genes CD14 and Toll-like receptor 4, and microbial exposures, as well as the detoxifying gene family glutathione-S-transferase and environmental tobacco smoke exposure and air pollutants. Gene by environment interaction is important in asthma pathogenesis, and future studies should take the interaction of both factors into account.

The significance of beta2-adrenergic receptor polymorphisms in asthma

PURPOSE OF REVIEW

The gene that encodes the beta2-adrenergic receptor (ADRB2) is one of the most studied candidate genes in asthma. This review examines recent articles of the relationship between ADRB2 polymorphisms and asthma.

RECENT FINDINGS

Candidate gene association studies of ADRB2 and asthma have been dominated by analyses of the two common non-synonymous coding single nucleotide polymorphisms, Arg16Gly and Glu27Gly. Published studies have yielded inconsistent results. Three recent meta-analyses on the effects of these two polymorphisms have found no associations with asthma, although there were suggestions of associations with other asthma-related phenotypes, such as nocturnal asthma and asthma severity. Other recent studies have investigated other single nucleotide polymorphisms in this gene (i.e. single nucleotide polymorphisms in the promoter region and other single nucleotide polymorphisms in the coding region). These analyses have investigated the association between these single nucleotide polymorphisms (and haplotypes of these polymorphisms) and asthma-related phenotypes such as lung function, airways hyperresponsiveness, and response to a bronchodilator, and have suggested that certain regions of the gene may be associated with different phenotypes. Results from these studies, however, have also been inconsistent.

SUMMARY

Polymorphisms of ADRB2 are not major risk factors for the development of asthma. These polymorphisms are likely to be important, however, in determining drug response. Future studies need to fully characterize all of the variation in the gene and perform comprehensive association studies. Finally, interactions between ADRB2 and other genes in the beta-agonist pathway are an important and active area of research that will shed more light on inter-individual differences in drug response.

Asthma, genes, and air pollution

OBJECTIVE

The objective of this article is to evaluate genetic risks associated with the pulmonary response to air pollutants, including particulates and ozone.

METHODS

A comprehensive review of articles related to the genetics of asthma with particular attention to air pollution was conducted through a search of the National Library of Medicine's PubMed database.

RESULTS

Asthma, which affects over 15 million people in the United States, is characterized by inflammation leading to reversible airflow obstruction. Triggered by exposure to numerous occupational and environmental agents, asthma has long been considered to occur more frequently in families, with upwards of a 50% higher rate in the offspring of parents with asthma. Asthma genetic studies have used two major methods: mapping techniques that pinpoint gene loci and studies that identify genes and polymorphisms associated with various asthma mechanisms such as inflammatory mediators. The most consistently replicated chromosomal regions associated with asthma have been chromosomes 2q, 5q, 6p, 12 q, and 13q. Because the formation of reactive oxygen species is a major aspect of the inflammatory process of asthma, genetic aberrations associated with antioxidants such as glutathione S-transferase (GST) may shed light on reasons why some people with asthma seem more at risk of exacerbations as a result of air pollution. People with a polymorphism at the GSTP 1 locus, which codes for GST, one of a family of pulmonary antioxidants, have higher rates of asthma. Children in Mexico City with the GSTM1 null genotype demonstrated significant ozone-related decrements in lung function. Animal studies support the key role of antioxidants in reducing the inflammatory response associated with exposure to diesel exhaust particles.

CONCLUSIONS

Oxidative stress is a key mechanism underlying the toxic effects of exposure to some types of air pollution. Asthmatics with the null genotype for the antioxidant, GST, seem more at risk of the pulmonary effects of air pollution.

Risk factors for asthma in young adults: a co-twin control study

BACKGROUND

The liability to asthma is influenced both by genetic and environmental factors. The objective of this study was to identify risk factors for asthma in young adult twin pairs during an 8-year period.

METHODS

From the birth cohorts 1953-1982 of the Danish Twin Registry, 6,090 twin pairs who were initially unaffected with respect to asthma at a nationwide questionnaire-based study in 1994 participated in a similar follow-up study in 2002. Subjects were regarded incident asthma cases when responding affirmatively to the question 'Do you have, or have you ever had asthma'? in 2002. Pairs in which only one twin developed asthma -- discordant pairs -- were identified and conditional logistic regression was applied to detect effects of risk factors.

RESULTS

A total of 126 monozygotic (MZ) and 273 dizygotic (DZ) discordant twin pairs were identified. In MZ twins hay fever (OR = 3.16, 95% CI: 1.29-7.73, P = 0.007) and exercise (OR for inactivity = 0.35, 95% CI: 0.13-0.91, P = 0.023) were significantly associated with asthma, whereas in DZ twins, hay fever (OR = 2.44, 95% CI: 1.44-4.13, P = 0.001), eczema (OR = 1.96, 95% CI: 1.02-3.78, P = 0.040), female sex (OR between males and females = 0.54, 95% CI: 0.36-0.80, P = 0.002), and increasing levels of body mass index (BMI; OR per unit = 1.11, 95% CI: 1.02-1.20, P = 0.009) were significant predictors of asthma.

CONCLUSIONS

Hay fever, eczema, female sex, exercise and increasing levels of BMI were risk factors for asthma in young adults. The different risk profile observed in MZ twins compared with DZ twins may reflect an underlying genetic vulnerability shared between those risk factors and asthma.

Systematic review and meta-analysis of the association between {beta}2-adrenoceptor polymorphisms and asthma: a HuGE review

A number of studies have investigated two common polymorphisms in the beta(2)-adrenoceptor gene, Arg/Gly16 and Gln/Glu27, in relation to asthma susceptibility. The authors performed a meta-analysis of each polymorphism, as well as haplotype analysis, for adult and pediatric populations separately, using published data, supplemented by additional data requested from the original authors. Individual analysis detected no effect of Arg/Gly16 in adults but did suggest a recessive protective effect of Gly16 for children, with an odds ratio of 0.71 (95% confidence interval (CI): 0.53, 0.96) compared with the other genotypes. Results for Gln/Glu27 in adults seem to indicate that heterozygotes are at decreased risk of asthma than either homozygote (odds ratio = 0.73, 95% CI: 0.62, 0.87), although the studies are heterogeneous; in children, the Glu/Glu genotype has a decreased risk of asthma (odds ratio = 0.60, 95% CI: 0.35, 0.99) compared with the other genotypes. Despite the proximity of these two polymorphic sites, the linkage disequilibrium coefficient of 0.41 was not high (p < 0.001). Haplotype analysis suggests that there may be an interaction between the two sites, with a lower risk of asthma associated with the Glu27 allele (compared with Gln27), and that this risk is modified by the allele at position 16.

The incidence of asthma in young adults

STUDY OBJECTIVES

Longitudinal data on adult asthma are sparse. The objectives of this study were to determine the incidence of asthma and to establish the risk factors for the development of asthma in subjects who were 12 to 41 years old over an 8-year period.

DESIGN

From birth cohorts over the period 1953 to 1982 in The Danish Twin Registry, 19,349 subjects with no history of asthma, as determined by a questionnaire-based survey in 1994, answered a follow-up questionnaire in 2002. The subjects were regarded as incident asthma cases when answering "yes" to the question "Do you have, or have you ever had asthma?" in 2002, and "no" to the same question in 1994.

RESULTS

A total of 838 cases (4.3%) of new asthma were identified in 2002. The incidence rates of asthma were 4.5 and 6.4 per 1,000 person-years, respectively, among male and female subjects. For all ages, the probability of adult-onset asthma was greater for female subjects (odds ratio [OR], 1.49; p < 0.001), and for both sexes there was a slow decline in probability with increasing age. There was a positive association between increasing body mass index (BMI) and risk of adult-onset asthma applying to both sexes (OR, 1.05 per unit; p < 0.001). Furthermore, positive associations were found between incident asthma and a history of hay fever (OR: male subjects, 4.2; female subjects, 3.7; p < 0.001), eczema (OR: male subjects, 3.5; female subjects, 2.0; p < 0.001), and both (OR: male subjects, 6.9; female subjects, 8.0; p < 0.001).

CONCLUSIONS

There is a continuing high incidence of asthma past childhood that is most pronounced among female subjects. Increasing levels of BMI are associated with a greater likelihood of developing asthma for both sexes. A substantial portion of cases of adult asthma is preceded by upper airway allergic symptoms and/or eczema, thus indicating a shared pathogenesis.

Decreased physical activity among Head Start children with a history of wheezing: use of an accelerometer to measure activity

Asthma is a severe problem among inner city children, and recent evidence suggests that both allergen exposure and lifestyle can impact the disease early in childhood. This study was designed to investigate the association between physical activity and wheezing among a population of inner city children enrolling in Head Start. The parents of children aged 3-5 years responded to a questionnaire (N = 144) to determine the presence and severity of wheezing and asthma. Information was also gathered regarding home environment, food frequency, and presence of other allergic diseases. Serum was obtained to measure total IgE and specific IgE levels to common allergens. Height and weight for body mass index were recorded. Lastly, motion sensor wristwatches (Actiwatch) were worn continuously by a subset of these children (n = 54) for 6 or 7 days. Physical activity measured with the motion sensor was decreased among children with a history of wheezing. The significant differences involved those measures of activity relating to prolonged or sustained physical activity. The correlates of asthma associated with decreased levels of physical activity included: 1) a history of wheezing in the last 12 months, 2) the diagnosis of asthma, and 3) presentation to the emergency room in the last 12 months for wheezing or asthma. In a preschool-age population, decreased physical activity was observed among children with a history of asthma or wheezing. Decreased physical activity could contribute to persistence of asthma or put children at higher risk for obesity and other chronic diseases.

Association of defensin beta-1 gene polymorphisms with asthma

BACKGROUND

Defensins are antimicrobial peptides that may take part in airway inflammation and hyperresponsiveness.

OBJECTIVE

We characterized the genetic diversity in the defensin beta-1 (DEFB1) locus and tested for an association between common genetic variants and asthma diagnosis.

METHODS

To identify single nucleotide polymorphisms (SNPs), we resequenced this gene in 23 self-defined European Americans and 24 African Americans. To test whether DEFB1 genetic variants are associated with asthma, we genotyped 4 haplotype-tag SNPs in 517 asthmatic and 519 control samples from the Nurses' Health Study (NHS) and performed a case-control association analysis. To replicate these findings, we evaluated the DEFB1 polymorphisms in a second cohort from the Childhood Asthma Management Program.

RESULTS

Within the NHS, single SNP testing suggested an association between asthma diagnosis and a 5' genomic SNP (g.-1816 T>C; P = .025) and intronic SNP (IVS+692 G>A; P = .054). A significant association between haplotype (Adenine, Cytosine, Thymine, Adenine [ACTA]) and asthma ( P = .024) was also identified. Associations between asthma diagnosis and both DEFB1 polymorphisms were observed in Childhood Asthma Management Program, a second cohort: g.-1816 T>C and IVS+692 G>A demonstrated significant transmission distortion ( P = .05 and .007, respectively). Transmission distortion was not observed in male subjects. The rare alleles (-1816C and +692A) were undertransmitted to offspring with asthma, suggesting a protective effect, contrary to the findings in the NHS cohort. Similar effects were evident at the haplotype level: ACTA was undertransmitted ( P = .04) and was more prominent in female subjects ( P = .007).

CONCLUSION

Variation in DEFB1 contributes to asthma diagnosis, with apparent gender-specific effects.

Obesity and asthma in 11-12 year old New Zealand children in 1989 and 2000

BACKGROUND

There has been a concurrent increase in the prevalence of obesity and asthma in recent years in New Zealand and other countries.

METHODS

Two cross sectional surveys performed in 1989 and 2000 were used to test this association in children of mean age 11.7 years. Body mass index (BMI) was calculated as weight/height2 (kg/m2) and obesity and overweight defined according to an international standard. Standard questions were used to measure the prevalence of asthma symptoms.

RESULTS

Significant increases in the prevalence of reported symptoms and disease between 1989 and 2000 were not explained by a concurrent increase in the prevalence of obesity. In 2000, multivariate analysis showed that increasing BMI standard deviation score was significantly associated with current wheeze (p=0.002), inhaled steroid use (p=0.004), and the use of any medication (p=0.001). None of the associations was significantly different for boys or girls.

CONCLUSION

There is some evidence for an association of obesity with asthma symptoms and treatment but this does not explain the increasing prevalence of this disease.

Effect of weight reduction on respiratory function and airway reactivity in obese women

BACKGROUND

Population-based studies have documented an association between obesity and an increased prevalence of asthma in women.

METHODS

We prospectively studied 58 obese women with a body mass index of > 30 kg/m(2), 24 of whom had asthma, who were enrolled in an intensive 6-month weight loss program to determine whether loss of body mass would be correlated with improvements in bronchial reactivity, lung function, and disease-specific health status.

RESULTS

Patients lost an average of 20 kg over the 6-month period. For every 10% relative loss of weight, the FVC improved by 92 mL (p = 0.05) and the FEV(1) improved by 73 mL (p = 0.04), however, bronchial reactivity did not significantly change with weight loss (p = 0.23). Patients who lost > 13% of their pretreatment weight experienced improvements in FEV(1) (p = 0.01), FVC (p = 0.02), and total lung capacity (p = 0.05) compared to patients in the lowest quartile who failed to lose significant amounts of weight. Neither group experienced any significant change in methacholine responsiveness (p = 0.57). Patients who completed the 6-month weight loss program experienced improvements in respiratory health status, irrespective of weight loss.

CONCLUSION

We concluded that weight loss can improve lung function in obese women, however, the improvements appear to be independent of changes in airway reactivity.

Therapeutic strategies for allergic airways diseases

Asthma and allergic rhinitis are airways allergic diseases and different aspects of these diseases are discussed in this paper. Both diseases require specific treatment but the airways are a continuum and it has been shown that concomitant treatment in patients suffering from both diseases has a better effect than treating only one of the diseases. Furthermore, treatment of allergic rhinitis in asthmatic patients reduces the risk of hospital admission due to asthma and improves bronchial hyper-responsiveness. Anti-inflammatory therapy, particularly with local steroids, is the single most important treatment for airways allergic diseases. Some studies have shown the importance of starting early after diagnosing asthma but the issue of how early in life to start inhaled steroids is still being debated. Also leukotriene antagonists have been shown to have beneficial effects in many patients and can be used in conjunction with inhaled steroids. Combination therapy with inhaled steroids and inhaled beta(2)-agonists has been shown to be effective in adults but this has not yet been fully documented in children. Optimal treatment of exercise-induced asthma is important to enable children and adolescents to fulfill their developmental possibilities. Allergy vaccination has traditionally been used for treating airways allergic diseases. It is often given for allergic rhinitis when pharmacotherapy is not providing full symptom control. One recent study has suggested that allergy vaccination may possibly help to prevent the development of asthma in the child with allergic rhinitis. More research is needed on asthma allergy vaccination. Concordance with treatment may often be difficult and efforts should be taken to ensure the best concordance possible.

Association between beta2-adrenoceptor polymorphisms and asthma diagnosis among Mexican adults

BACKGROUND

Recent studies demonstrate that genetic variations in the human beta(2)-adrenergic receptor (beta(2)AR) structure at codons 16 and 27 alter receptor function in vitro and are associated with asthma severity and airway hyperresponsiveness but have not been linked to asthma diagnosis. The nature of the relation in a more homogeneous population is uncertain.

OBJECTIVE

We determined frequencies of these polymorphisms to explore the association between beta(2)AR haplotypes and asthma diagnosis and phenotype.

METHODS

This is a population-based, case-control study that involves a total sample of 907 unrelated Mexican Mestizos. Genotyping at beta(2)AR was identified by polymerase chain reaction-restriction fragment length polymorphism analysis. Multivariate logistic regression analysis was used to estimate the odds ratio (OR) of the association between beta(2)AR haplotype status and asthma diagnosis.

RESULTS

A significant inverse association was found between subjects with Glu27 allele (OR, 0.5; 95% CI, 0.4 to 0.7) and Gly16-Glu27 alleles (OR, 0.5; 95% CI, 0.3 to 0.8) and asthma. Sex differences in this association were explored, given the complex relation between sex and asthma. Among men, a positive association was present between the "Gly16 allele without Glu27" (OR, 2.9; 95% CI, 1.26 to 6.8) and asthma. In contrast, a lower risk of asthma was found among women Gly16-Glu27 alleles (OR, 0.3; 95% CI, 0.2 to 0.6). Nocturnal asthma was associated with the Gly16 allele (OR, 1.8; 95% CI, 1.3 to 2.6).

CONCLUSIONS

Variation in the beta(2)AR gene is associated in the pathogenesis of asthma and acts as a disease modifier in nocturnal asthma.

New asthma targets: recent clinical and preclinical advances

Current asthma therapy is directed at the relief of chronic inflammation or improving lung function through bronchodilation. These approaches treat the overt symptoms of asthma but do not approach underlying causes of the disease. Such therapies have limited efficacy and for a number of patients the disease remains poorly controlled. The short-term future of asthma therapy will probably focus on the treatment of multiple symptoms to provide improved lung function. Long-term approaches to asthma will have to focus on modulation of the mechanisms that are the underlying causes of the various asthmatic pathophysiologies. These targets include a number of TH2-type T-cell-generated cytokines and chemokines, G-protein-coupled receptors, TH2-related transcription factors, neurotrophins and adhesion molecules. Additional new targets and understanding of asthma may also arise from genetic analysis.

Waging war on physical inactivity: using modern molecular ammunition against an ancient enemy

A hypothesis is presented based on a coalescence of anthropological estimations of Homo sapiens' phenotypes in the Late Paleolithic era 10,000 years ago, with Darwinian natural selection synergized with Neel's idea of the so-called thrifty gene. It is proposed that humans inherited genes that were evolved to support a physically active lifestyle. It is further postulated that physical inactivity in sedentary societies directly contributes to multiple chronic health disorders. Therefore, it is imperative to identify the underlying genetic and cellular/biochemical bases of why sedentary living produces chronic health conditions. This will allow society to improve its ability to effect beneficial lifestyle changes and hence improve the overall quality of living. To win the war against physical inactivity and the myriad of chronic health conditions produced because of physical inactivity, a multifactorial approach is needed, which includes successful preventive medicine, drug development, optimal target selection, and efficacious clinical therapy. All of these approaches require a thorough understanding of fundamental biology and how the dysregulated molecular circuitry caused by physical inactivity produces clinically overt disease. The purpose of this review is to summarize the vast armamentarium at our disposal in the form of the extensive scientific basis underlying how physical inactivity affects at least 20 of the most deadly chronic disorders. We hope that this information will provide readers with a starting point for developing additional strategies of their own in the ongoing war against inactivity-induced chronic health conditions.

Reducing disparities in asthma care: priorities for research--National Heart, Lung, and Blood Institute workshop report

Minority groups with diverse racial and ethnic heritages and persons living in poverty are much more likely to die of asthma and to require emergency care for exacerbations of asthma than white persons not living in poverty. The National Heart, Lung, and Blood Institute convened a multidisciplinary group of expert scientists and clinicians to review current research aimed at understanding risk factors for these disparities in asthma health outcomes, to describe key barriers to improving asthma outcomes, and to establish priorities for future research. Education programs for asthma and other chronic diseases were reviewed. Successful elements of clinic and community-based programs were identified. Factors potentially involved in producing disparities include gene-environment interaction, psychologic and social factors, and socioeconomic status. Stress potentially contributes to asthma morbidity at both the individual and community level. Recommendations are made to stimulate research to understand risk factors for disparities and their mechanisms (e.g., gene-by-environment interactions and the role of stress), to define appropriate research designs and methods for evaluating behavioral and community interventions, and to examine how differential access to care contributes to morbidity. Research is encouraged to identify strategies that improve cultural adaptation and adoption of proven programs in a variety of populations.