The relationship between residential exposure to atmospheric pollution and circulating miRNA in adults living in an urban area in northern France

INTRODUCTION

MicroRNAs are epigenetic regulatory factors capable of silencing the expression of target genes and might mediate the effects of air pollution on health. The objective of the present population-based study was to investigate the association between microRNA expression and long-term, residential exposure to atmospheric PM₁₀ and NO₂.

METHOD

We included 998 non-smoking adult participants from the cross-sectional ELISABET survey (2010-2014) in the Lille urban area of France. The mean residential annual pollution levels were estimated with an atmospheric dispersion modelling system. Ten microRNAs were selected on the basis of the literature data, together with two housekeeping microRNAs (miR-93-5p and miR-191-5p) and were quantified with RT-qPCRs. Multivariate linear regression models were used to study the association between microRNAs and air pollution. The threshold for statistical significance (after correction for the FDR) was set to p < 0.1.

RESULTS

The mean annual exposure between 2011 and the year of inclusion was 26.4 ± 2.0 µg/m³ for PM₁₀ and 24.7 ± 5.1 µg/m³ for NO₂. Each 2 µg/m³ increment in PM₁₀ exposure was associated with an 8.6% increment (95%CI [3.1; 14.3]; p_FDR = 0.019) in miR-451a expression. A 5 µg/m³ increment in NO₂ exposure was associated with a 5.3% increment ([0.7; 10]; p_FDR = 0.056) in miR451a expression, a 3.6% decrement (95%CI [-6.1; -1.1]; p_FDR = 0.052) in miR-223-3p expression, a 3.8% decrement (95%CI[-6.8; -0.7]; p_FDR = 0.079) in miR-28-3p expression, a 4.3% decrement (95%CI [-7.7; -0.8]; p_FDR = 0.055) in miR-146a-5p expression, and a 4.0% decrement (95% CI[-7.4; -0.4]; p_FDR = 0.059) in miR-23a-5p expression. The difference between the two housekeeping microRNAs miR-93-5p and miR-191-5p was also associated with PM₁₀ and NO₂ exposure.

CONCLUSION

Our results suggest that circulating miRNAs are potentially valuable biomarkers of the effects of air pollution.

Plasma thymic stromal lymphopoietin (TSLP) in adults with non-severe asthma: the EGEA study

Thymic stromal lymphopoietin (TSLP), a cytokine involved in severe asthma treatment, was never studied in non-severe asthma.Among 969 adults from a large epidemiological study, cross-sectional analyses showed that plasma TSLP levels were associated with increased age and BMI, male sex, smoking and high TSLP levels (one IQR increase) with current asthma and poor lung function. High TSLP levels were also associated with persistence of asthma attacks (aOR=2.14 (95% CI 1.23 to 3.72)) and dyspnoea (aOR=2.71 (95% CI 1.39 to 5.28)) 10 years later.Our results suggest that TSLP could be a cytokine of interest in non-severe asthma, and its determinants of circulating levels could be considered in asthma management.

Respiratory function in uncomplicated type 1 diabetes: Blunted during exercise even though normal at rest!

AIMS

Type 1 diabetes is associated with a substantially increased risk of impaired lung function, which may impair aerobic fitness. We therefore aimed to examine the ventilatory response during maximal exercise and the pulmonary diffusion capacity function at rest in individuals with uncomplicated type 1 diabetes.

METHODS

In all, 17 adults with type 1 diabetes free from micro-macrovascular complications (glycated haemoglobin: 8.0 ± 1.3%), and 17 non-diabetic adults, carefully matched to the type 1 diabetes group according to gender, age, level of physical activity and body composition, participated in our study. Lung function was assessed by spirometry and measurements of the combined diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) at rest. Subjects performed a maximal exercise test during which the respiratory parameters were measured.

RESULTS

At rest, DLCO (30.4 ± 6.1 ml min^-1  mmHg^-1 vs. 31.4 ± 5.7 ml min^-1 mmHg^-1 , respectively, p = 0.2), its determinants Dm (membrane diffusion capacity) and Vc (pulmonary capillary volume) were comparable among type 1 diabetes and control groups, respectively. Nevertheless, spirometry parameters (forced vital capacity = 4.9 ± 1.0 L vs. 5.5 ± 1.0 L, p < 0.05; forced expiratory volume 1 = 4.0 ± 0.7 L vs. 4.3 ± 0.7 L, p < 0.05) were lower in individuals with type 1 diabetes, although in the predicted normal range. During exercise, ventilatory response to exercise was different between the two groups: tidal volume was lower in type 1 diabetes vs. individuals without diabetes (p < 0.05). Type 1 diabetes showed a reduced VO_2max (34.7 ± 6.8 vs. 37.9 ± 6.3, respectively, p = 0.04) in comparison to healthy subjects.

CONCLUSIONS

Individuals with uncomplicated type 1 diabetes display normal alveolar-capillary diffusion capacity and at rest, while their forced vital capacity, tidal volumes and VO₂ are reduced during maximal exercise.

Whole pulmonary assessment 1 year after paediatric acute respiratory distress syndrome: prospective multicentre study

Background

Long-term pulmonary sequelae, including 1-year thoracic computed tomography (CT) sequelae of paediatric acute respiratory distress syndrome (ARDS) remain unknown. The purpose of the study was to determine pulmonary abnormalities in child survivors of pulmonary (p-ARDS) and extra-pulmonary ARDS (ep-ARDS) 1 year after paediatric intensive care unit discharge (PICUD).

Methods

Prospective multicentre study in four paediatric academic centres between 2005 and 2014. Patients with ARDS were assessed 1 year after PICUD with respiratory symptom questionnaire, thoracic CT and pulmonary function tests (PFT).

Results

39 patients (31 p-ARDS) aged 1.1–16.2 years were assessed. Respiratory symptoms at rest or exercise and/or respiratory maintenance treatment were reported in 23 (74%) of children with p-ARDS but in 1 (13%) of those with ep-ARDS. Thoracic CT abnormalities were observed in 18 (60%) of children with p-ARDS and 4 (50%) of those with ep-ARDS. Diffuse and more important CT abnormalities, such as ground glass opacities or mosaic perfusion patterns, were observed in 5 (13%) of children, all with p-ARDS. PFT abnormalities were observed in 30 (86%) of patients: lung hyperinflation and/or obstructive pattern in 12 (34%) children, restrictive abnormalities in 6 (50%), mild decrease in diffusing capacity in 2 (38%) and 6-min walking distance decrease in 11 (73%). Important PFT abnormalities were observed in 7 (20%) children, all with p-ARDS. Increasing driving pressure (max plateau pressure—max positive end-expiratory pressure) was correlated with increasing CT-scan abnormalities and increasing functional residual capacity (more hyperinflation) (p < 0.005).

Conclusions

Children surviving ARDS requiring mechanical ventilation present frequent respiratory symptoms, significant CT-scan and PFT abnormalities 1 year after PICUD. This highlights the need for a systematic pulmonary assessment of these children.

Trial registration The study was registered on Clinical Trials.gov PRS (ID NCT01435889)

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01050-4.

Short-term and residential exposure to air pollution: Associations with inflammatory biomarker levels in adults living in northern France

INTRODUCTION

Air pollution has an impact on health, and low-grade inflammation might be one of the underlying mechanisms. The objective of the present study of adults from northern France was to assess the associations between short-term and residential exposure to air pollution and levels of various inflammatory biomarkers.

METHODS

The cross-sectional Enquête Littoral Souffle Air Biologie Environnement (ELISABET) study was conducted from 2011 to 2013 in the Lille and Dunkirk urban areas of northern France. Here, we evaluated the associations between PM₁₀, NO₂ and O₃ exposure (on the day of the blood sample collection and on the day before, and the mean annual residential level) and levels of the inflammatory biomarkers high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-17A, IL-22, and tumor necrosis factor α.

RESULTS

We assessed 3074 participants for the association with hsCRP and a subsample of 982 non-smokers from Lille for the association with plasma cytokine levels. A 10 μg/m³ increment in PM₁₀ and NO₂ levels on the day of sample collection and on the day before was associated with a higher hsCRP concentration (3.43% [0.68; 6.25] and 1.75% [-1.96; 5.61], respectively, whereas a 10 μg/m³ increment in O₃ was associated with lower hsCRP concentration (-1.2% [-3.95; 1.64]). The associations between mean annual exposure and the hsCRP level were not significant. Likewise, the associations between exposure and plasma cytokine levels were not statistically significant.

CONCLUSION

Short-term exposure to air pollution was associated with higher serum hsCRP levels in adult residents of two urban areas in northern France. Our results suggest that along with other factors, low-grade inflammation might explain the harmful effects of air pollution on health.

Identification of novel genes influencing eosinophil-specific protein levels in asthma families

BACKGROUND

Eosinophils play a key role in the asthma allergic response by releasing cytotoxic molecules such as eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) that generate epithelium damages.

OBJECTIVE

To identify genetic variants influencing ECP and EDN levels in asthma-ascertained families.

METHODS

We performed univariate and bivariate genome-wide association analyses of ECP and EDN levels in 1,018 subjects from EGEA study with follow-up in 153 subjects from SLSJ study and combined the results of these two studies through meta-analysis. We then conducted Bayesian statistical fine-mapping together with quantitative trait locus and functional annotation analyses to identify the most likely functional genetic variants and candidate genes.

RESULTS

We identified five genome-wide significant loci (P<5x10^-8) including seven distinct signals associated with ECP and/or EDN levels. The genes targeted by our fine-mapping and functional search include RNASE2 and RNASE3 (14q11) which encode EDN and ECP respectively and four other genes which regulate ECP/EDN levels. These four genes were the following: JAK1 (1p31) a transcription factor with a key role in the immune response and a potential therapeutic target for eosinophilic asthma, ARHGAP25 (2p13) involved in leukocyte recruitment to inflammatory sites, NDUFA4 (7p21) encoding a component of the mitochondrial respiratory chain and involved in cellular response to stress and CTSL (9q22) involved in immune response, extra-cellular remodeling and allergic inflammation.

CONCLUSION

This study demonstrates that the analysis of specific phenotypes produced by eosinophils allows identifying genes with a major role in allergic response and inflammation and offering potential therapeutic targets for asthma.

Blood eosinophil cationic protein and eosinophil-derived neurotoxin are associated with different asthma expression and evolution in adults

BACKGROUND

Eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) are proteins released by activated eosinophils whose role in adult asthma remains unclear.

OBJECTIVE

To study associations between ECP, EDN and various asthma characteristics in adults from the Epidemiological Study on the Genetics and Environment of Asthma (EGEA).

METHODS

Plasma ECP and EDN levels were measured by ELISA. Cross-sectional analyses were performed in 941 adults (43±16 years old, 39% with asthma) at EGEA2 (2003-2007). Longitudinal analyses investigated the associations between EDN level at EGEA2 and changes in asthma characteristics between EGEA2 and EGEA3 (2011-2013, n=817). We used generalised estimated equations adjusted for age, sex, smoking status and body mass index to take into account familial dependence.

RESULTS

At EGEA2, both high ECP and EDN levels were associated with current asthma (adjusted OR (aOR) (95% CI): 1.69 (1.35-2.12) and 2.12 (1.76-2.57)). Among asthmatics, high EDN level was associated with asthma attacks (aOR: 1.50 (1.13-1.99)), wheezing and breathlessness (aOR: 1.38 (1.05-1.80)), use of asthma treatments (aOR: 1.91 (1.37-2.68)) and bronchial hyper-responsiveness (aOR: 2.03 (1.38-2.97)), even after further adjustment on ECP. High ECP level was associated with high neutrophil count and tended to be associated with chronic bronchitis. High EDN level at EGEA2 was associated with persistent asthma (aOR: 1.62 (1.04-2.52)), nocturnal symptoms (aOR from 2.19 to 3.57), worsening wheezing and breathlessness (aOR: 1.97 (1.36-2.85)) and nocturnal shortness of breath (aOR: 1.44 (1.04-1.98)) between EGEA2 and EGEA3.

CONCLUSIONS

EDN and ECP were associated with different asthma expression in adults. EDN could be a potential biomarker to monitor asthma evolution in adults.

Association between occupational exposure to irritant agents and a distinct asthma endotype in adults

AIM

The biological mechanisms of work-related asthma induced by irritants remain unclear. We investigated the associations between occupational exposure to irritants and respiratory endotypes previously identified among never asthmatics (NA) and current asthmatics (CA) integrating clinical characteristics and biomarkers related to oxidative stress and inflammation.

METHODS

We used cross-sectional data from 999 adults (mean 45 years old, 46% men) from the case-control and familial Epidemiological study on the Genetics and Environments of Asthma (EGEA) study. Five respiratory endotypes have been identified using a cluster-based approach: NA1 (n=463) asymptomatic, NA2 (n=169) with respiratory symptoms, CA1 (n=50) with active treated adult-onset asthma, poor lung function, high blood neutrophil counts and high fluorescent oxidation products level, CA2 (n=203) with mild middle-age asthma, rhinitis and low immunoglobulin E level, and CA3 (n=114) with inactive/mild untreated allergic childhood-onset asthma. Occupational exposure to irritants during the current or last held job was assessed by the updated occupational asthma-specific job-exposure matrix (levels of exposure: no/medium/high). Associations between irritants and each respiratory endotype (NA1 asymptomatic as reference) were studied using logistic regressions adjusted for age, sex and smoking status.

RESULTS

Prevalence of high occupational exposure to irritants was 7% in NA1, 6% in NA2, 16% in CA1, 7% in CA2 and 10% in CA3. High exposure to irritants was associated with CA1 (adjusted OR aOR, (95% CI) 2.7 (1.0 to 7.3)). Exposure to irritants was not significantly associated with other endotypes (aOR range: 0.8 to 1.5).

CONCLUSION

Occupational exposure to irritants was associated with a distinct respiratory endotype suggesting oxidative stress and neutrophilic inflammation as potential associated biological mechanisms.

Dramatic impact of morbid obesity on child lung development

OBJECTIVE

To assess the respiratory function and sleep characteristics of obese adults and children.

METHODS

All patients with non-syndromic, severe obesity (BMI ≥3 z-scores for children and ≥40.00kg/m² for adults), referred for pulmonary function tests at Lille University Hospital, were retrospectively included.

RESULTS

A total of 69 children (mean±SD BMI 36.8±6.7 and mean BMI z-score 4.7±1.0) and 70 adults were included (mean BMI 45.7±6.2). Metabolic syndrome was diagnosed in 13 children (26%) and 40 adults (80%). Reduced lung volumes were observed in 34 children (50.0%) and 16 adults (24.0%) and both the mean functional residual capacity (FRC) and the mean residual volume (RV) were lower in children than in adults (FRC: -1.7±2.1 z-score in children vs. -1.0±1.1 in adults, P=0.026; and RV: -0.8±1.2 z-score in children vs. -0.1±1.1 in adults, P=0.002). The prevalence of severe obstructive sleep apnea syndrome was greater in adults (40.7% vs. 18.8%, P=0.007). Children had a higher average oxygen saturation (median of 96.0% [91.0-98.0] vs. 93.0% [76.0-97.0] in adults, P<0.0001).

CONCLUSION

Obesity has consequences for lung volumes in children; however, a longitudinal study is needed to determine the impact on pulmonary expansion and growth.

Circulating biomarkers of nitric oxide bioactivity and impaired muscle vasoreactivity to exercise in adults with uncomplicated type 1 diabetes

AIMS/HYPOTHESIS

Early compromised endothelial function challenges the ability of individuals with type 1 diabetes to perform normal physical exercise. The exact mechanisms underlying this vascular limitation remain unknown, but may involve either formation or metabolism of nitric oxide (NO), a major vasodilator, whose activity is known to be compromised by oxidative stress.

METHODS

Muscle microvascular reactivity (near-infrared spectroscopy) to an incremental exhaustive bout of exercise was assessed in 22 adults with uncomplicated type 1 diabetes (HbA_1c 64.5 ± 15.7 mmol/mol; 8.0 ± 1.4%) and in 21 healthy individuals (18-40 years of age). NO-related substrates/metabolites were also measured in the blood along with other vasoactive compounds and oxidative stress markers; measurements were taken at rest, at peak exercise and after 15 min of recovery. Demographic characteristics, body composition, smoking status and diet were comparable in both groups.

RESULTS

Maximal oxygen uptake was impaired in individuals with type 1 diabetes compared with in healthy participants (35.6 ± 7.7 vs 39.6 ± 6.8 ml min^-1 kg^-1, p < 0.01) despite comparable levels of habitual physical activity (moderate to vigorous physical activity by accelerometery, 234.9 ± 160.0 vs 280.1 ± 114.9 min/week). Compared with non-diabetic participants, individuals with type 1 diabetes also displayed a blunted exercise-induced vasoreactivity (muscle blood volume at peak exercise as reflected by ∆ total haemoglobin, 2.03 ± 5.82 vs 5.33 ± 5.54 μmol/l; interaction 'exercise' × 'group', p < 0.05); this was accompanied by lower K⁺ concentration (p < 0.05), reduced plasma L-arginine (p < 0.05)-in particular when HbA_1c was high (mean estimation: -4.0, p < 0.05)-and lower plasma urate levels (p < 0.01). Nonetheless, exhaustive exercise did not worsen lipid peroxidation or other oxidative stress biomarkers, and erythrocytic enzymatic antioxidant resources were mobilised to a comparable extent in both groups. Nitrite and total nitrosation products, which are potential alternative NO sources, were similarly unaltered. Graphical abstract CONCLUSIONS/INTERPRETATION: Participants with uncomplicated type 1 diabetes displayed reduced availability of L-arginine, the essential substrate for enzymatic nitric oxide synthesis, as well as lower levels of the major plasma antioxidant, urate. Lower urate levels may reflect a defect in the activity of xanthine oxidase, an enzyme capable of producing NO from nitrite under hypoxic conditions. Thus, both canonical and non-canonical NO production may be reduced. However, neither of these changes exacerbated exercise-induced oxidative stress.

TRIAL REGISTRATION

clinicaltrials.gov NCT02051504.

Endotypes identified by cluster analysis in asthmatics and non-asthmatics and their clinical characteristics at follow-up: the case-control EGEA study

Background

Identifying relevant asthma endotypes may be the first step towards improving asthma management. We aimed identifying respiratory endotypes in adults using a cluster analysis and to compare their clinical characteristics at follow-up.

Methods

The analysis was performed separately among current asthmatics (CA, n=402) and never asthmatics (NA, n=666) from the first follow-up of the French EGEA study (EGEA2). Cluster analysis jointly considered 4 demographic, 22 clinical/functional (respiratory symptoms, asthma treatments, lung function) and four blood biological (allergy-related, inflammation-related and oxidative stress-related biomarkers) characteristics at EGEA2. The clinical characteristics at follow-up (EGEA3) were compared according to the endotype identified at EGEA2.

Results

We identified five respiratory endotypes, three among CA and two among NA: CA1 (n=53) with active treated adult-onset asthma, poor lung function, chronic cough and phlegm and dyspnoea, high body mass index, and high blood neutrophil count and fluorescent oxidation products level; CA2 (n=219) with mild asthma and rhinitis; CA3 (n=130) with inactive/mild untreated allergic childhood-onset asthma, high frequency of current smokers and low frequency of attacks of breathlessness at rest, and high IgE level; NA1 (n=489) asymptomatic, and NA2 (n=177) with respiratory symptoms, high blood neutrophil and eosinophil counts. CA1 had poor asthma control and high leptin level, CA2 had hyper-responsiveness and high interleukin (IL)-1Ra, IL-5, IL-7, IL-8, IL-10, IL-13 and TNF-α levels, and NA2 had high leptin and C reactive protein levels. Ten years later, asthmatics in CA1 had worse clinical characteristics whereas those in CA3 had better respiratory outcomes than CA2; NA in NA2 had more respiratory symptoms and higher rate of incident asthma than those in NA1.

Conclusion

These results highlight the interest to jointly consider clinical and biological characteristics in cluster analyses to identify endotypes among adults with or without asthma.

Evolution of high-resolution CT-scan in systemic sclerosis-associated interstitial lung disease: Description and prognosis factors

OBJECTIVE

The aims of our study were to describe the evolution of interstitial lung disease (ILD) extent on HRCT scan in systemic sclerosis (SSc), to identify baseline prognostic factors associated with ILD evolution and to assess whether the evolution of pulmonary function tests (PFTs) correlated with this evolution.

METHODS

58 SSc with ILD (SSc-ILD) patients were included. All HRCT scans and PFTs available were collected. We modelized PFTs and HRCT scans evolution using linear mixed model with random effect.

RESULTS

Patients underwent a median number of 3 HRCT scans (total n = 203) and 5 PFTs (total n = 329), during a mean follow-up of 5.3 ± 4.9 years. Mean SSc duration was 2.5 ± 3.1 years at the diagnosis of ILD. Mean baseline ILD extent was 32.3 ± 28.7%. We found a significant mean progression of ILD extent on serial HRCT scans of 0.92 ± 0.36% per year (p = 0.018). Male sex, diffuse cutaneous SSc (dcSSc), presence of anti-topoisomerase 1 antibodies, a higher DLCO, limited ILD and a low coarseness score at baseline in bivariate analysis, and presence of antitopoisomerase 1 antibodies and a coarseness score of 0 in multivariate analysis, were associated with faster progression of ILD extent over time There was a significant correlation between the progression of ILD extent and the decline of DLCO but only a trend for FVC. ILD extent at baseline and during follow-up was associated with survival.

CONCLUSION

Male sex, dcSSc, anti-topoisomerase 1 antibodies and a less severe ILD at baseline were associated with a faster progression of ILD over time. Evolution of DLCO significantly correlated with change in ILD extent on HRCT scan. Our study helps defining the profile of patients at risk of experiencing a progression of ILD on HRCT scans.

Residential exposure to outdoor air pollution and adult lung function, with focus on small airway obstruction

Although a growing body of evidence suggests that chronic exposure to outdoor air pollution is linked to a decline in lung function, data on flow at low lung volumes that may be more specific of small airway obstruction are still scarce. We aimed to study the associations between residential exposure to air pollution and lung function, with specific focus on small airways obstruction. We assessed 2995 French participants (aged between 40 and 65) in the ELISABET cross-sectional survey. Residential exposures to nitrogen dioxide (NO₂), particulate matter with a diameter <10 μm (PM₁₀) and sulphur dioxide (SO₂) were assessed. The spirometric parameters were forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and forced expiratory flow between 25% and 75% of FVC (FEF25-75) and at 75% of FVC (FEF75). Coefficients in linear regression models were expressed as the z-score [95% confidence interval] for an increment of 5 μg/m³ in NO₂ and 2 μg/m³ in PM₁₀ and SO₂. NO₂ was associated with significantly lower values of FEV1 (-0.10 [-0.15;-0.05]), FVC (-0.06 [-0.11;-0.02]), FEV1/FVC (-0.07 [-0.11;-0.03]), FEF25-75 (-0.09 [-0.14;-0.05]) and FEF75 (-0.08 [-0.12;-0.04]). PM₁₀ was associated with significantly lower values of FEV1 (-0.10 [-0.15;-0.04]), FVC (-0.06 [-0.11;-0.01]), FEV1/FVC (-0.06 [‒0.11;-0.01]), FEF25-75 (-0.08 [-0.13;-0.03]) and FEF75 (-0.08 [-0.12;-0.04]). SO₂ was associated with significantly lower values of FEV1 (-0.09 [-0.16;-0.02]), FEV1/FVC (-0.07 [-0.13;-0.01]), FEF25-75 (-0.09 [-0.15;-0.02]) and FEF75 (-0.08 [-0.14;-0.03]) but not FVC (-0.05 [-0.11; 0.009]). Even though spatial variations in pollutant levels were low, residential exposure to outdoor air pollution was associated with lower lung function, including lower FEF25-75 and FEF75 suggesting small airway obstruction.

Muscle Oxygen Supply and Use in Type 1 Diabetes, From Ambient Air to the Mitochondrial Respiratory Chain: Is There a Limiting Step?

OBJECTIVE

Long before clinical complications of type 1 diabetes (T1D) develop, oxygen supply and use can be altered during activities of daily life. We examined in patients with uncomplicated T1D all steps of the oxygen pathway, from the lungs to the mitochondria, using an integrative ex vivo (muscle biopsies) and in vivo (during exercise) approach.

RESEARCH DESIGN AND METHODS

We compared 16 adults with T1D with 16 strictly matched healthy control subjects. We assessed lung diffusion capacity for carbon monoxide and nitric oxide, exercise-induced changes in arterial O₂ content (SaO₂, PaO₂, hemoglobin), muscle blood volume, and O₂ extraction (via near-infrared spectroscopy). We analyzed blood samples for metabolic and hormonal vasoactive moieties and factors that are able to shift the O₂-hemoglobin dissociation curve. Mitochondrial oxidative capacities were assessed in permeabilized vastus lateralis muscle fibers.

RESULTS

Lung diffusion capacity and arterial O₂ transport were normal in patients with T1D. However, those patients displayed blunted exercise-induced increases in muscle blood volume, despite higher serum insulin, and in O₂ extraction, despite higher erythrocyte 2,3-diphosphoglycerate. Although complex I- and complex II-supported mitochondrial respirations were unaltered, complex IV capacity (relative to complex I capacity) was impaired in patients with T1D, and this was even more apparent in those with long-standing diabetes and high HbA_1c. [Formula: see text]O_2max was lower in patients with T1D than in the control subjects.

CONCLUSIONS

Early defects in microvascular delivery of blood to skeletal muscle and in complex IV capacity in the mitochondrial respiratory chain may negatively impact aerobic fitness. These findings are clinically relevant considering the main role of skeletal muscle oxidation in whole-body glucose disposal.

The association between blood cadmium and glycated haemoglobin among never-, former, and current smokers: A cross-sectional study in France

INTRODUCTION

The association between cadmium levels in the body and diabetes has been extensively studied, with sometimes contrasting results. Smoking is the primary non-occupational source of cadmium, and constitutes a risk factor for diabetes. One can therefore hypothesize that the putative association with cadmium is actually explained by tobacco. To fully control for this confounding factor, we studied the relationship between blood cadmium and glycated haemoglobin (HbA1c) levels separately in never-, former and current smokers.

METHODS

We studied a sample of 2749 middle-aged adults from the cross-sectional ELISABET survey in and around the cities of Lille and Dunkirk; none had chronic kidney disease or a history of haematological disorders, and none were taking antidiabetic medication. The blood cadmium level-HbA1c associations in never-, former and current smokers were studied in separate multivariate models. The covariables included age, sex, city, educational level, tobacco consumption (or passive smoking, for the never-smokers), body mass index, estimated glomerular filtration rate, and (to take account of the within-batch effect) the cadmium batch number.

RESULTS

In the multivariate analysis, a significant association between cadmium and HbA1c levels was found in all three smoking status subgroups. A 0.1 μg/L increment in blood cadmium was associated with an HbA1c increase [95% confidence interval] of 0.016% [0.003; 0.029] among never-smokers, 0.024% [0.010; 0.037] among former smokers, and 0.020% [0.012; 0.029] among current smokers.

CONCLUSIONS

The observation of a significant association between the blood cadmium concentration and HbA1c levels in a group of never-smokers strengthens the hypothesis whereby diabetes is associated with cadmium per se and not solely with tobacco use. The small effect size observed in our population of never smokers with low levels of exposure to cadmium suggested that the risk attributable to this metal is not high. However, the impact of exposure to high cadmium levels (such as occupational exposure) on the risk of diabetes might be of concern.

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.

Global Lung Initiative spirometry references in healthy 3-15-year-old French children

The Global Lung Initiative (GLI) Task Force published references for spirometry derived from data collated from a large population of healthy individuals aged 3–95 years, from 26 countries [1]. However data from French children were not included in these equations and external validation of the references is recommended [2]. Our study's aim was to compare z-score values and distributions obtained using the references of Zapletalet al. [3, 4] (Zap-Ref) for preschool [3] and school children [4] currently used in France with those obtained using the GLI's references (GLI-Ref) as applied to data from 3–15 year-old healthy French children from northern France.

Global Lung Initiative spirometry references satisfactorily fit data of healthy 3- to 15-year-old French childrenhttp://bit.ly/2Z2922R

High level of fluorescent oxidation products and worsening of asthma control over time

High Fluorescent oxidation products level (FlOPs), a global oxidative stress biomarker, was associated cross-sectionally with poor asthma outcomes but its longitudinal association with asthma evolution has never been examined. We aimed to study the associations between FlOPs level at baseline and changes in current asthma, asthma attacks and asthma control status over 8 years. We used data from the second survey of the French EGEA cohort study as baseline and the third survey as follow-up. At baseline, the mean age of the 489 participants with ever asthma was 39 (± 16) years, 49% were women. Among participants with controlled asthma at baseline, high FlOPs level was significantly associated with worsening of asthma control at follow-up (odds-ratio adjusted for age, sex and smoking status (95% CI): 2.27 (1.32–3.90). No other significant associations were observed. In conclusion, results suggest FlOPs as a predictor of asthma evolution in adults and a good candidate marker in asthma management.

Data-driven adult asthma phenotypes based on clinical characteristics are associated with asthma outcomes twenty years later

BACKGROUND

Research based on cluster analyses led to the identification of particular phenotypes confirming phenotypic heterogeneity of asthma. The long-term clinical course of asthma phenotypes defined by clustering analysis remains unknown, although it is a key aspect to underpin their clinical relevance. We aimed to estimate risk of poor asthma events between asthma clusters identified 20 years earlier.

METHODS

The study relied on two cohorts of adults with asthma with 20-year follow-up, ECRHS (European Community Respiratory Health Survey) and EGEA (Epidemiological study on Genetics and Environment of Asthma). Regression models were used to compare asthma characteristics (current asthma, asthma exacerbations, asthma control, quality of life, and FEV₁ ) at follow-up and the course of FEV₁  between seven cluster-based asthma phenotypes identified 20 years earlier.

RESULTS

The analysis included 1325 adults with ever asthma. For each asthma characteristic assessed at follow-up, the risk for adverse outcomes differed significantly between the seven asthma clusters identified at baseline. As compared with the mildest asthma phenotype, ORs (95% CI) for asthma exacerbations varied from 0.9 (0.4 to 2.0) to 4.0 (2.0 to 7.8) and the regression estimates (95% CI) for FEV₁ % predicted varied from 0.6 (-3.5 to 4.6) to -9.9 (-14.2 to -5.5) between clusters. Change in FEV₁ over time did not differ significantly across clusters.

CONCLUSION

Our findings show that the long-term risk for poor asthma outcomes differed between comprehensive adult asthma phenotypes identified 20 years earlier, and suggest a strong tracking of asthma activity and impaired lung function over time.

Short-term exposure to air pollution: Associations with lung function and inflammatory markers in non-smoking, healthy adults

INTRODUCTION

Air pollution impacts health by increasing mortality and the incidence of acute events in unhealthy individuals. In contrast, the acute effects of pollution in healthy individuals are less obvious. The present study was designed to evaluate the associations between short-term exposure to air pollution on one hand and lung function, and inflammatory markers on the other in middle-aged, non-smoking adults with no respiratory disease, in two urban areas in northern France.

METHODS

A sample of 1506 non-smoking adults (aged from 40 to 65) with no respiratory disease was selected from the participants in the 2011-2013 cross-sectional Enquête Littoral Souffle Air Biologie Environnement (ELISABET) survey in two urban areas in the northern France. We evaluated the associations between (i) mean levels of particulate matter with aerodynamic diameter < 10 μm (PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) exposure on the day and the day before the study examination for each participant, and (ii) spirometry data and levels of inflammatory markers. Coefficients of multiple linear regression models were expressed (except for the forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio) as the percentage change [95% confidence interval] per 10 μg increment in each pollutant.

RESULTS

Levels of PM₁₀, NO₂ and O₃ exposure were below or only close to the World Health Organization's recommended limits in our two study areas. An increment in NO₂ levels was significantly associated with a lower FEV1/FVC ratio (-0.38 [-0.64; -0.12]), a lower forced expiratory flow between 25% and 75% of FVC (FEF25-75%) (-1.70 [-3.15; -0.23]), and a lower forced expiratory flow measured at 75% of FVC (FEF75%) (-3.07 [-4.92; -1.18]). An increment in PM₁₀ levels was associated with lower FEF75% (-1.41 [-2.79; -0.01]) and a non-significant elevation in serum levels of high-sensitivity C-reactive protein (+3.48 [-0.25; 7.36], p = 0.07). Lastly, an increment in O₃ levels was associated with a significantly higher blood eosinophil count (+2.41 [0.10; 4.77]) and a non-significant elevation in fractional exhaled nitric oxide (+2.93 [-0.16; 6.13], p = 0.06).

CONCLUSION

A short-term exposure to air pollution was associated with a subclinical decrement in distal lung function and increment in inflammatory markers in healthy inhabitants of two urban areas in France. If these exploratory results are confirmed, this could suggest that even moderate levels of air pollution could have an impact on respiratory health on the general population, and not solely on susceptible individuals.