New asthma biomarkers: shorter telomeres, longer disease?

Accelerated biological age mediates the associations between sleep patterns and chronic respiratory diseases: Findings from the UK Biobank Cohort

BACKGROUND

Unhealthy sleep patterns and accelerated biological age are frequently associated with multiple chronic respiratory diseases (CRDs), including COPD, asthma, and interstitial lung disease (ILD). However, few studies have explored the role of biological age in the relationship between sleep patterns and CRDs.

OBJECTIVES

To explore the association between sleep patterns and CRD, and the extent to which biological age mediates the relationship between sleep patterns and CRD.

METHODS

This was a prospective cohort study based on UK Biobank. The sleep score was derived from five self-reported sleep traits: sleep duration, daytime sleepiness, chronotype, snoring, and insomnia. The score ranged from 0 (least healthy) to 5 (healthiest). Biological age was represented by PhenoAgeAccel.

RESULTS

Among 303,588 participants, 11,105 (3.7 %), 9,380 (3.1 %), and 1,667 (0.5 %) were diagnosed with asthma, COPD, and ILD, respectively. Each 1-point increase in the sleep score was associated with a 0.156-year reduction in PhenoAgeAccel, and 14.3 %, 12.4 %, and 6.7 % reduction in asthma, COPD, and ILD, respectively. For each 1-year increase in PhenoAgeAccel, the risk of asthma, COPD, and ILD increased by 2.8 %, 4.3 %, and 5.7 %, respectively. PhenoAgeAccel mediated the associations between the sleep score and asthma, COPD, and ILD, with a mediated proportion (95 % CI) of 2.81 % (2.35 % to 3.27 %), 4.94 % (4.23 % to 5.66 %), and 12.48 % (10.43 % to 14.53 %), respectively.

CONCLUSION

A better sleep score was significantly associated with younger biological age and decreased risk of CRDs, with biological age playing a mediating role in the association between sleep score and CRDs.

Associations of combined phenotypic ageing and genetic risk with incidence of chronic respiratory diseases in the UK Biobank: a prospective cohort study

BACKGROUND

Accelerated biological ageing has been associated with an increased risk of several chronic respiratory diseases. However, the associations between phenotypic age, a new biological age indicator based on clinical chemistry biomarkers, and common chronic respiratory diseases have not been evaluated.

METHODS

We analysed data from 308 592 participants at baseline in the UK Biobank. The phenotypic age was calculated from chronological age and nine clinical chemistry biomarkers, including albumin, alkaline phosphatase, creatinine, glucose, C-reactive protein, lymphocyte percent, mean cell volume, red cell distribution width and white blood cell count. Furthermore, phenotypic age acceleration (PhenoAgeAccel) was calculated by regressing phenotypic age on chronological age. The associations of PhenoAgeAccel with incident common chronic respiratory diseases and cross-sectional lung function were investigated. Moreover, we constructed polygenic risk scores and evaluated whether PhenoAgeAccel modified the effect of genetic susceptibility on chronic respiratory diseases and lung function.

RESULTS

The results showed significant associations of PhenoAgeAccel with increased risk of idiopathic pulmonary fibrosis (IPF) (hazard ratio (HR) 1.52, 95% CI 1.45-1.59), COPD (HR 1.54, 95% CI 1.51-1.57) and asthma (HR 1.18, 95% CI 1.15-1.20) per 5-year increase and decreased lung function. There was an additive interaction between PhenoAgeAccel and the genetic risk for IPF and COPD. Participants with high genetic risk and who were biologically older had the highest risk of incident IPF (HR 5.24, 95% CI 3.91-7.02), COPD (HR 2.99, 95% CI 2.66-3.36) and asthma (HR 2.07, 95% CI 1.86-2.31). Mediation analysis indicated that PhenoAgeAccel could mediate 10∼20% of the associations between smoking and chronic respiratory diseases, while ∼10% of the associations between particulate matter with aerodynamic diameter <2.5 µm and the disorders were mediated by PhenoAgeAccel.

CONCLUSION

PhenoAgeAccel was significantly associated with incident risk of common chronic respiratory diseases and decreased lung function and could serve as a novel clinical biomarker.

A Novel Association between YKL-40, a Marker of Structural Lung Disease, and Short Telomere Length in 10-Year-Old Children with Bronchopulmonary Dysplasia

Extremely preterm infants are born with immature lungs and are exposed to an inflammatory environment as a result of oxidative stress. This may lead to airway remodeling, cellular aging and the development of bronchopulmonary dysplasia (BPD). Reliable markers that predict the long-term consequences of BPD in infancy are still lacking. We analyzed two biomarkers of cellular aging and lung function, telomere length and YKL-40, respectively, at 10 years of age in children born preterm with a history of BPD (n = 29). For comparison, these markers were also evaluated in sex-and-age-matched children born at term with childhood asthma (n = 28). Relative telomere length (RTL) was measured in whole blood with qPCR and serum YKL-40 with ELISA, and both were studied in relation to gas exchange and the regional ventilation/perfusion ratio using three-dimensional V/Q-scintigraphy (single photon emission computer tomography, SPECT) in children with BPD. Higher levels of YKL-40 were associated with shorter leukocyte RTL (Pearson's correlation: -0.55, p = 0.002), but were not associated with a lower degree of matching between ventilation and perfusion within the lung. Serum YKL-40 levels were significantly higher in children with BPD compared to children with asthma (17.7 vs. 13.2 ng/mL, p < 0.01). High levels of YKL-40 and short RTLs were associated to the need for ventilatory support more than 1 month in the neonatal period (p < 0.01). The link between enhanced telomere shortening in childhood and structural remodeling of the lung, as observed in children with former BPD but not in children with asthma at the age of 10 years, suggests altered lung development related to prematurity and early life inflammatory exposure. In conclusion, relative telomere length and YKL-40 may serve as biomarkers of altered lung development as a result of early-life inflammation in children with a history of prematurity.

Does the oxidative stress play a role in the associations between outdoor air pollution and persistent asthma in adults? Findings from the EGEA study

BACKGROUND

Evidences that oxidative stress plays a role in the associations between outdoor air pollution and asthma are growing. We aimed to study the role of plasma fluorescent oxidation products levels (FlOPs; an oxidative stress-related biomarker), as potential mediators, in the associations between outdoor air pollution and persistent asthma.

METHODS

Analyses were conducted in 204 adult asthmatics followed up in the French case-control and family study on asthma (EGEA; the Epidemiological study of the Genetic and Environmental factors of Asthma). Persistent asthma was defined as having current asthma at EGEA2 (baseline, 2003-2007) and EGEA3 (follow-up, 2011-2013). Exposures to nitrogen dioxide, nitrogen oxides, road traffic, particulate matter with a diameter ≤ 10 μm (PM₁₀) and ≤ 2.5 μm were estimated by ESCAPE models (2009-2010), and ozone (O₃) by IFEN models (2004). We used a mediation analysis to assess the mediated effect by FlOPs levels and the interaction between FlOPs levels and air pollution.

RESULTS

FlOPs levels increased with PM₁₀ and O₃ (adjusted β = 0.04 (95%CI 0.001-0.08), aβ = 0.04 (95%CI 0.009-0.07) per 10 μg/m³, respectively), and the risk of persistent asthma increased with FlOPs levels (aOR = 1.81 (95%CI 1.08-3.02)). The risk of persistent asthma decreased with exposures to NO₂, NOx and PM_2.5 (aOR ranging from 0.62 to 0.94), and increased with exposures to PM₁₀, O₃, O_3-summer and road traffic, the greater effect being observed for O₃ (aOR = 1.78, 95% CI 0.73-4.37, per 10 μg/m³). Using mediation analysis, we observed a positive total effect (aOR = 2.16, 95%CI 0.70-11.9), a positive direct effect of O₃ on persistent asthma (OR = 1.68, 95%CI 0.57-7.25), and a positive indirect effect mediated by FIOPs levels (aOR = 1.28 (95%CI 1.01-2.29)) accounting for 41% of the total effect.

CONCLUSIONS

Our results add insights on the role of oxidative stress in the association between air pollution and persistent asthma.

Ambient air pollution, asthma drug response, and telomere length in African American youth

BACKGROUND

Telomere length (TL) can serve as a potential biomarker for conditions associated with chronic oxidative stress and inflammation, such as asthma. Air pollution can induce oxidative stress. Understanding the relationship between TL, asthma, and air pollution is important for identifying risk factors contributing to unhealthy aging in children.

OBJECTIVES

We sought to investigate associations between exposures to ambient air pollutants and TL in African American children and adolescents and to examine whether African ancestry, asthma status, and steroid medication use alter the association.

METHODS

Linear regression was used to examine associations between absolute telomere length (aTL) and estimated annual average residential ozone (O3) and fine particulate matter with a diameter of 2.5 μm or less (PM2.5) exposures in a cross-sectional analysis of 1072 children in an existing asthma case-control study. African ancestry, asthma status, and use of steroid medications were examined as effect modifiers.

RESULTS

Participants' aTLs were measured by using quantitative PCR. A 1-ppb and 1 μg/m3 increase in annual average exposure to O3 and PM2.5 were associated with a decrease in aTL of 37.1 kilo-base pair (kb; 95% CI, -66.7 to -7.4 kb) and 57.1 kb (95% CI, -118.1 to 3.9 kb), respectively. African ancestry and asthma were not effect modifiers; however, exposure to steroid medications modified the relationships between TL and pollutants. Past-year exposure to O3 and PM2.5 was associated with shorter TLs in patients without steroid use.

CONCLUSION

Exposure to air pollution was associated with shorter TLs in nonasthmatic children and adolescents. This was not the case for asthmatic children as a group, but those receiving steroid medication had less shortening than those not using steroids. Reduced exposure to air pollution in childhood might help to preserve TL.

Asthma over the Adult Life Course: Gender and Hormonal Influences

Asthma is a common disorder that affects genders differently across the life span. Earlier in life, it is more common in boys. At puberty, asthma becomes more common and often more severe in girls and women. The effect of sex hormones on asthma incidence and its severity is difficult to differentiate from other asthma severity risk factors, such as racial background, socioeconomic factors, obesity, atopy, environmental exposure, and, in particular, lung aging. Recognizing gender-associated and age-associated differences is important to understanding the pathobiology of asthma and to providing effective education and personalized care for patients with asthma across the life course.

Shorter telomeres in non-smoking patients with airflow limitation

BACKGROUND

Cross-sectional and longitudinal studies describe shorter telomeres in patients with chronic obstructive pulmonary disease (COPD) compared to matched non-COPD controls, but the relationship is confounded by tobacco consumption. We hypothesized that telomere shortening would be similar between non-smoking and smoking individuals with airflow limitation and shorter than non-obstructed controls.

METHODS

Telomere length (T/S) was measured by qPCR in blood leukocytes of 80 non-smoking patients and 80 age-matched smokers with airflow limitation. Forty non-smoker healthy individuals served as controls. Anthropometrics, lung function, previous and current comorbidities were recorded in all individuals. Relationship between telomere length and clinical and functional variables were explored in the three groups.

RESULTS

Telomeres length was similar in non-smokers and smoker individuals with airflow limitation (T/S = 0.61 ± 0.19 vs. 0.60 ± 0.23, p > 0.05) respectively. Telomere length was significantly shorter in both groups compared to healthy controls (T/S 0.79 ± 0.40; p = 0.01) independent from age and sex. No significant association was found between the telomere length and clinical or lung function parameters.

CONCLUSIONS

Telomere shortening is associated with airflow limitation independent of smoking status. Weather premature ageing or biologically determined shorter telomeres are responsible for this finding remain to be determined.