A study of asthma severity in adult twins

Comparative Dynamic Pulmonary Function Tests Between Apparently Healthy Young Adult Offspring of Asthmatic and Non-asthmatic Parents: A Pilot Study

Background While the hereditary component of asthma has been established, its influence on early respiratory function changes in otherwise healthy offspring remains to be explored. Dynamic lung function tests assess airflow in and out of the lungs, providing valuable insights into respiratory health and detecting potential airflow limitations. This study aimed to compare the dynamic lung functions between offspring of asthmatic and non-asthmatic parents. Methodology A case-control design was employed comprising 30 cases (offspring of asthmatic parents) and 30 controls (offspring of non-asthmatic parents). Lung function parameters including forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC ratio, forced expiratory flow between 25% and 75% of the FVC (FEF 25-75%), and maximum mid-expiratory flow at 50% of the FVC (Vmax 50%) were measured. Statistical analysis was conducted to compare the parameters between cases and controls using the unpaired t-test. Results The mean age of controls was 20.46 ± 2.82 years and the cases was 19.83 ± 1.41 years. The study revealed that cases exhibited lower FEV1 and Vmax 50% values compared to controls, indicating potential airflow limitations and altered mid-exhalation flow rates in the offspring of asthmatic parents. While trends were observed in FVC, FEV1/FVC ratio, and FEF 25-75%, these differences were not statistically significant. Conclusions The findings suggest a potential association between parental asthma and altered lung function parameters, specifically in FEV1 and Vmax 50%, among their offspring. These early respiratory function changes underscore the potential impact of hereditary factors on lung health. Healthcare professionals should take parental asthma into account when evaluating lung functions. This may lead to earlier detection and intervention. Further investigation is warranted to elucidate the underlying mechanisms and long-term implications of these findings.

Altered intestinal microbiota in children with bronchiolitis

Objective

To investigate the correlation between the alteration of intestinal microbiota and disease in children with bronchiolitis.

Methods

Fifty seven children diagnosed with bronchiolitis from January 2020 to January 2022 in our pediatric department were included as the case group, and another 36 normal children were included as the control group. Stool and blood were collected from both groups for high-throughput sequencing, untargeted metabolite detection and ELISA. A mouse model of RSV infection was established to validate the results of clinical case detection.

Results

Body weight, passive smoking, and a host of other factors were possible as acute bronchiolitis influencing factors in the onset of acute bronchiolitis. The alpha diversity Shannon, Simpson and Pielou's evenness indices were significantly lower in children with acute bronchiolitis than in healthy children with gated levels of Firmicutes, Bacteroidetes and genus levels of Clostridium and other short chain fatty acid-producing bacteria. The relative abundance of short-chain fatty acid (SCFAs)-producing bacteria decreased and the abundance of genus-level sphingolipid-producing bacteria Sphingomonas increased; the progression of acute bronchiolitis is likely to be associated with the abundance of Clostridium and Sphingomonas and higher fecal amino acid concentrations, including FF-MAS, L-aspartic acid, thioinosinic acid, picolinic acid; supplementation with Clostridium butyricum significantly alleviated RSV infection-induced lung inflammation.

Conclusion

The progression of bronchiolitis may be associated with altered intestinal microbiota, decreased SCFAs and elevated sphingolipids metabolism in children. Some fecal bacteria and metabolites may predict the onset of bronchiolitis, and oral administration of Clostridium butyricum may alleviate RSV infection-induced pulmonary inflammation.

Functional abdominal pain disorders and asthma: two disorders, but similar pathophysiology?

INTRODUCTION

Functional abdominal pain disorders (FAPDs) and asthma are common ailments affecting both children and adults worldwide. Multiple studies have demonstrated an association between these two disorders. However, the exact reason for this observed association is not apparent.

AREAS COVERED

The current review has explored available literature and outlined multiple underlying pathophysiological mechanisms, common to both asthma and FAPDs, as possible reasons for this association.

EXPERT OPINION

Smooth muscle dysfunction, hypersensitivity and hyper-responsiveness, mucosal inflammation, and barrier dysfunction involving gastrointestinal and respiratory tracts are the main underlying pathophysiological mechanisms described for the generation of symptoms in FAPDs and asthma. In addition, alterations in neuroendocrine regulatory functions, immunological dysfunction, and microbial dysbiosis have been described in both disorders. We believe that the pathophysiological processes that were explored in this article would be able to expand the mechanisms of the association. The in-depth knowledge is needed to be converted to therapeutic and preventive strategies to improve the quality of care of children suffering from FAPDs and asthma.

The risk of asthma is increased among women with polycystic ovary syndrome: a twin study

Background

Recent registry studies have demonstrated a higher prevalence of asthma among women with polycystic ovary syndrome (PCOS). We aimed to assess the association and heritability of PCOS and asthma in a Danish twin cohort.

Methods

Data for 32 382 female twins from the Danish Twin Registry were included. Twins with PCOS were identified by searching the Danish National Patient Registry for International Classification of Diseases-10 code E28.2. Asthma was diagnosed by questionnaires.

Results

103 (0.3%) women had a PCOS diagnosis. The risk of asthma was increased among women with PCOS compared with women without (18% versus 9%, respectively; OR 2.11 (95% CI 1.13-3.96); p=0.02). After adjustment for age, body mass index, alcohol consumption and smoking status, the risk of asthma was still increased, but was no longer statistically significant (OR 1.54 (95% CI 0.75-3.17); p=0.24). Variance components analysis showed that shared environmental factors explained 49% (95% CI 24-68%) and unique environmental factors explained 51% (95% CI 32-76%) of the susceptibility to PCOS. For asthma, 44% (95% CI 28-61%) of the variance was explained by genetic factors, whereas 25% (95% CI 11-38%) was ascribable to shared environmental factors and 31% (95% CI 26-36%) to unique environmental factors.

Conclusion

The risk of asthma is twice as high among female twins with PCOS. The individual susceptibility to PCOS is mainly due to environmental factors and not genetics.

Influences of Maternal Factors Over Offspring Allergies and the Application for Food Allergy

The prevalence of food allergy has been steadily rising worldwide with the highest incidence noted among younger children, and increasingly recognized as a growing public concern. The first known ingestion of foods often causes allergic reaction, suggesting that sensitization of offspring with food allergens may occur during pregnancy and/or through breastfeeding. This creates a milieu that shapes the neonatal immune responses to these allergens. However, the effects of maternal allergen exposure and maternal sensitization with allergens on development of allergies in offspring remain controversial. This review discusses recent advances from human data in our understanding of how maternal factors, namely, food allergens, allergen-specific immunoglobulins, cytokines, genetics, and environmental factors transferred during pregnancy or breastfeeding influence offspring allergies and how such effects may be applicable to food allergy. Based on information obtained from mouse models of asthma and food allergy, the review also dissects the mechanisms by which maternal factors, including the impact of immune complexes, transforming growth factor-β, vitamin A, and regulatory T-cell responses, contribute to the induction of neonatal tolerance vs. development of allergic responses to maternally transferred allergens.

Asthma severity, nature or nurture: genetic determinants

PURPOSE OF REVIEW

This article reviews the progress in the search for the genetic determinants of severe asthma.

RECENT FINDINGS

Twin studies estimate that approximately 25% of the phenotypic variability in asthma severity is determined by genetic factors, with the remainder determined by nongenetic factors including environmental and psychosocial factors, behavioral traits, and comorbidities. Most genetic association studies of asthma severity performed to date are underpowered and not designed to clearly distinguish asthma severity variants from asthma susceptibility variants. However, the most recent genome-wide asthma severity association study, conducted in more than 57 000 individuals, demonstrated significant associations for 25 loci, including three not previously associated with asthma: GATA3, MUC5AC, and KIAA1109. Of these, the MUC5AC association was restricted to cohorts that included moderate-to-severe (but not mild) asthma. Additional insights from rare monogenic disorders that can present as severe asthma include recognition that loss-of-function variants in the filaggrin gene known to cause ichthyosis vulgaris are consistently associated with more severe asthma outcomes. Other notable loci of interest include RAD50-IL13 on chromosome 5q and the ORMDL3-GSDMB locus on chromosome 17q21.

SUMMARY

Severe asthma is a polygenic trait. Future research should explore the role of rare genetic variation and gene-by-environment interaction.

Chronic asthma-induced behavioral and hippocampal neuronal morphological changes are concurrent with BDNF, cofilin1 and Cdc42/RhoA alterations in immature mice

INTRODUCTION

Recent studies have found that persistent hypoxia caused by chronic asthma, especially during childhood, affects the development and function of the brain, but the mechanism is unclear. In the present study, BDNF and its signal pathway was investigated in mediating chronic asthma induced-neuronal changes that lead to behavior alterations.

METHODS

The chronic asthma model was induced by sensitization with ovalbumin for more than 9 weeks in immature mice. Morris water maze test (MWMT), open field test (OFT) and elevated plus maze test (EPMT) were used to conduct behavioral evaluation. Neuronal morphology in hippocampal CA1, CA3 and DG was assessed using ImageJ's Sholl plugin and RESCONSTRUCT software. BDNF signaling pathway related molecules was determined by Western blotting.

RESULTS

Chronic asthma does affect the behavioral performances of immature mice evaluated in MWMT, OFT, and EPMT. The analysis by three-dimensional reconstruction software found that following the behavioral alteration of asthmatic mice, dendritic changes also occurred in hippocampal neurons, including shortened dendrite length, significantly reduced number of dendritic branches, decreased density of dendritic spines, and reduced percentage of functional dendritic spine types. At the same time, by immunofluorescence and western blotting, we also found that alterations in dendritic morphology were consistent with activation of cofilin1 and changes in BDNF-Cdc42/RhoA levels. Some of the changes mentioned above can be alleviated by intranasal administration of budesonide.

CONCLUSION

Our data suggest that response similar to nicotine withdrawal or/and hypoxia induced by childhood chronic asthma enhances the BDNF-Cdc42/RhoA signaling pathway and activates cofilin1, leading to the remodeling of actin, causing the loss of dendritic spines and atrophy of dendrites, eventually resulting in behavioral alterations.

Infection-mediated asthma: etiology, mechanisms and treatment options, with focus on Chlamydia pneumoniae and macrolides

Asthma is a chronic respiratory disease characterized by reversible airway obstruction and airway hyperresponsiveness to non-specific bronchoconstriction agonists as the primary underlying pathophysiology. The worldwide incidence of asthma has increased dramatically in the last 40 years. According to World Health Organization (WHO) estimates, over 300 million children and adults worldwide currently suffer from this incurable disease and 255,000 die from the disease each year. It is now well accepted that asthma is a heterogeneous syndrome and many clinical subtypes have been described. Viral infections such as respiratory syncytial virus (RSV) and human rhinovirus (hRV) have been implicated in asthma exacerbation in children because of their ability to cause severe airway inflammation and wheezing. Infections with atypical bacteria also appear to play a role in the induction and exacerbation of asthma in both children and adults. Recent studies confirm the existence of an infectious asthma etiology mediated by Chlamydia pneumoniae (CP) and possibly by other viral, bacterial and fungal microbes. It is also likely that early-life infections with microbes such as CP could lead to alterations in the lung microbiome that significantly affect asthma risk and treatment outcomes. These infectious microbes may exacerbate the symptoms of established chronic asthma and may even contribute to the initial development of the clinical onset of the disease. It is now becoming more widely accepted that patterns of airway inflammation differ based on the trigger responsible for asthma initiation and exacerbation. Therefore, a better understanding of asthma subtypes is now being explored more aggressively, not only to decipher pathophysiologic mechanisms but also to select treatment and guide prognoses. This review will explore infection-mediated asthma with special emphasis on the protean manifestations of CP lung infection, clinical characteristics of infection-mediated asthma, mechanisms involved and antibiotic treatment outcomes.

Filaggrin gene loss-of-function mutations explain discordance of atopic dermatitis within dizygotic twin pairs

OBJECTIVES

This study was designed to examine the association between loss-of-function mutations in the filaggrin gene (FLG) and atopic dermatitis (AD) and asthma in adult twins.

METHODS

A previously well-characterized cohort of 575 adult twins were genotyped for the loss-of-function mutations in FLG (R501X, 2282del4 and R2447X) most common among northern Europeans. Subjects were examined for symptoms of atopic diseases as well as for lung function, airway responsiveness, and atopy.

RESULTS

In the whole population of twins, the risk for AD was significantly increased in individuals with FLG mutations in comparison with wild-type carriers (34.3% vs. 21.8%) after adjustment for possible confounders (odds ratio [OR] 1.92, 95% confidence interval [CI] 1.07-3.41; P = 0.028). A significant association was also observed for persistent AD (OR 2.10, 95% CI 1.02-4.36; P = 0.046). There were no significant differences in risk for asthma by FLG mutation status in individuals with and without AD, respectively (P-value for interaction, 0.595). In 11 dizygotic twin pairs discordant for FLG mutation status, risk for AD was higher in the twin carrying the FLG mutation (five of 11 [45.5%] twins had developed AD) than in the non-carrier co-twin (two of 11 [18.2%] twins had developed AD) (OR 2.50, 95% CI 0.45-13.85; P = 0.293). FLG status did not explain a significant proportion of the variation in AD (P = 0.328) or asthma (P = 0.321).

CONCLUSIONS

Filaggrin gene mutations are risk factors for the presence and persistence of AD and explain the discordance of AD within dizygotic twin pairs.

The contribution of twin studies to the understanding of the aetiology of asthma and atopic diseases

The prevalence of asthma and other atopic diseases has increased markedly during the past decades and the reasons for this are not fully understood. Asthma is still increasing in many parts of the world, notably in developing countries, and this emphasizes the importance of continuing research aimed at studying the aetiological factors of the disease and the causes of its increase in prevalence. Twin studies enable investigations into the genetic and environmental causes of individual variation in multifactorial diseases such as asthma. Thorough insight into these causes is important as this will ultimately guide the development of preventive strategies and targeted therapies. This review explores the contribution of twin studies to the understanding of the aetiology of asthma and atopic diseases.

Genetic factors explain half of all variance in serum eosinophil cationic protein

BACKGROUND

Eosinophil cationic protein (ECP) is one of four basic proteins of the secretory granules of eosinophils. It has a variety of functions associated with inflammatory responses. Little is known about the causes for variation in serum ECP levels.

AIM

To identify factors associated with variation in serum ECP and to determine the relative proportion of the variation in ECP due to genetic and non-genetic factors, in an adult twin sample.

METHODS

A sample of 575 twins, selected through a proband with self-reported asthma, had serum ECP, lung function, airway responsiveness to methacholine, exhaled nitric oxide, and skin test reactivity, measured. Linear regression analysis and variance component models were used to study factors associated with variation in ECP and the relative genetic influence on ECP levels.

RESULTS

Sex (regression coefficient = -0.107, P < 0.001), body mass index (BMI) (0.007, P = 0.028), and airway responsiveness to methacholine (0.074, P = 0.001) were significantly associated with ECP. Adjusted for these factors, ECP correlated 0.53 (P < 0.001) and 0.27 (P = 0.001) in monozygotic and dizygotic twins, respectively (P-value for difference = 0.05). According to the most parsimonious variance component model, genetic factors accounted for 57% (CI: 42-72%, P < 0.001) of the variance in ECP levels, whereas the remainder (43%) was ascribable to non-shared environmental factors. The genetic correlation between ECP and airway responsiveness to methacholine was statistically non-significant (r = -0.11, P = 0.50).

CONCLUSION

Around half of all variance in serum ECP is explained by genetic factors. Serum ECP is influenced by sex, BMI, and airway responsiveness. Serum ECP and airway responsiveness seem not to share genetic variance.

Early menarche is associated with increased risk of asthma: Prospective population-based study of twins

AIM

To examine the association between early menarche and risk of post-menarcheal asthma.

METHODS

Using data from two multidisciplinary questionnaire surveys, conducted eight years apart, we prospectively studied 10,648 female twins, 12-41 years of age, from the nationwide Danish Twin Registry. Early menarche was defined as menarche before 12 years of age. We performed a cohort analysis and a co-twin control analysis including twin pairs discordant for incident asthma.

RESULTS

Early menarche was observed in 9.3% of the individuals. The eight-year cumulative incidence of asthma was higher in girls with early menarche compared to girls without early menarche (7.4 vs. 4.5%), OR = 1.71 (1.31-2.22), p < 0.001; also after adjustment for BMI, current age, physical activity, education, and smoking, OR = 1.53 (1.15-2.04), p = 0.003. The unadjusted risk of asthma was increased by 8% (1-15%), p = 0.041 per year earlier menarche occurred. Among 167 twin pairs discordant for incident asthma, there was a non-significant tendency towards early menarche being more common in the asthmatic than the non-asthmatic co-twin (12.0 vs. 9.6%), OR = 1.57 (0.61-4.05), p = 0.350. The risk of asthma was not uniform in discordant monozygotic and dizygotic twins.

CONCLUSION

Early menarche is associated with increased risk of asthma among Danish female twins independently of BMI, age, physical activity, educational level and smoking. Results indicate a complex relationship possibly mediated through innate and non-genetic effects.

Genetics of asthma: an introduction for the clinician

Asthma runs in families, and children of asthmatic parents are at increased risk of asthma. Prediction of disease risk is pivotal for the clinician when counselling atopic families. However, this is not always an easy task bearing in mind the vast and ever-increasing knowledge about asthma genetics. The advent of new genotyping technologies has made it possible to sequence in great detail the human genome for asthma-associated variants, and accordingly, recent decades have witnessed an explosion in the number of rare and common variants associated with disease risk. This review presents an overview of methods and advances in asthma genetics in an attempt to help the clinician keep track of the most important knowledge in the field.

Tribute to dr louis keith: twin and physician extraordinaire/twin research reports: influences on asthma severity; chimerism revisited; DNA strand break repair/media reports: twins born apart; elevated twin frequencies; celebrity father of twins; conjoined twinning

The International Society for Twin Studies has lost a valued friend and colleague. Dr Louis Keith, Emeritus Professor of Obstetrics and Gynecology at Northwestern University, in Chicago, passed away on Sunday, July 6, 2014. His life and work with twins will be acknowledged at the November 2014 International Twin Congress in Budapest, Hungary. Next, twin research reports on the severity of asthma symptoms, a case of chimerism, and factors affecting DNA breakage and repair mechanisms are reviewed. Media reports cover twins born apart, elevated twin frequencies, a celebrity father of twins, and a family's decision to keep conjoined twins together.

A twin study of early-childhood asthma in Puerto Ricans

BACKGROUND

The relative contributions of genetics and environment to asthma in Hispanics or to asthma in children younger than 3 years are not well understood.

OBJECTIVE

To examine the relative contributions of genetics and environment to early-childhood asthma by performing a longitudinal twin study of asthma in Puerto Rican children ≤ 3 years old.

METHODS

678 twin infants from the Puerto Rico Neo-Natal Twin Registry were assessed for asthma at age 1 year, with follow-up data obtained for 624 twins at age 3 years. Zygosity was determined by DNA microsatellite profiling. Structural equation modeling was performed for three phenotypes at ages 1 and 3 years: physician-diagnosed asthma, asthma medication use in the past year, and ≥ 1 hospitalization for asthma in the past year. Models were additionally adjusted for early-life environmental tobacco smoke exposure, sex, and age.

RESULTS

The prevalences of physician-diagnosed asthma, asthma medication use, and hospitalization for asthma were 11.6%, 10.8%, 4.9% at age 1 year, and 34.1%, 40.1%, and 8.5% at 3 years, respectively. Shared environmental effects contributed to the majority of variance in susceptibility to physician-diagnosed asthma and asthma medication use in the first year of life (84%-86%), while genetic effects drove variance in all phenotypes (45%-65%) at age 3 years. Early-life environmental tobacco smoke, sex, and age contributed to variance in susceptibility.

CONCLUSION

Our longitudinal study in Puerto Rican twins demonstrates a changing contribution of shared environmental effects to liability for physician-diagnosed asthma and asthma medication use between ages 1 and 3 years. Early-life environmental tobacco smoke reduction could markedly reduce asthma morbidity in young Puerto Rican children.

Meta-analysis of genome-wide association studies identifies ten loci influencing allergic sensitization

Allergen-specific immunoglobulin E (present in allergic sensitization) has a central role in the pathogenesis of allergic disease. We performed the first large-scale genome-wide association study (GWAS) of allergic sensitization in 5,789 affected individuals and 10,056 controls and followed up the top SNP at each of 26 loci in 6,114 affected individuals and 9,920 controls. We increased the number of susceptibility loci with genome-wide significant association with allergic sensitization from three to ten, including SNPs in or near TLR6, C11orf30, STAT6, SLC25A46, HLA-DQB1, IL1RL1, LPP, MYC, IL2 and HLA-B. All the top SNPs were associated with allergic symptoms in an independent study. Risk-associated variants at these ten loci were estimated to account for at least 25% of allergic sensitization and allergic rhinitis. Understanding the molecular mechanisms underlying these associations may provide new insights into the etiology of allergic disease.

Personalised medicine and asthma diagnostics/management

Human beings come in all shapes and sizes. Heterogeneity makes life interesting, but leads to inter-individual variation in disease susceptibility and response to therapy. One major health challenge is to develop "personalised medicine"; therapeutic interventions tailored to an individual to ensure optimal treatment of disease. Asthma is a heterogeneous disease with several different phenotypes triggered by multiple gene-environment interactions. Inhaled corticosteroids and β2-agonists have been the mainstay asthma therapies for 30 years, but they are not effective in all patients, while high costs and side-effects also drive the need for better targeted treatment of asthma. Pharmacogenetics is the study of variations in the genetic code for proteins in signaling pathways targeted by pharmacological therapies. Biomarkers are biological markers obtained from patients that can aid in asthma diagnosis, prediction of treatment response, and monitoring of disease control. This review presents a broad discussion of the use of genetic profiling and biomarkers to better diagnose, monitor, and tailor the treatment of asthmatics. We also discuss possible future developments in personalised medicine, including the construction of artificially engineered airway tissues containing a patient's own cells for use as personalised drug-testing tools.