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Chronic obstructive pulmonary disease (COPD) and asthma are characterised by increased oxidative stress in the lungs. The precise contribution of this stress to COPD aetiology remains unclear, partly due to the confounding influence of physiological ageing. Previous reports of increased oxidative stress in bronchoalveolar lavage (BAL) samples from individuals with COPD may at least in part be attributable to the subjects’ age. This study investigated whether increased metal concentrations at the air–lung interface would contribute to oxidative stress in the lungs. We analysed BAL samples from young and old never-smokers, young asthmatic never-smokers, older smokers without COPD and COPD patients (both current and ex-smokers). Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify a range of transition metals, including iron, copper, zinc, arsenic and cadmium. BAL concentrations of copper and zinc were significantly lower in young groups compared to the older groups, irrespective of smoking status or disease (p < 0.001 for both). BAL copper was significantly associated with several markers of oxidative stress, all of which were elevated with age: glutathione disulphide (ρ = 0.50, p < 0.001), dehydroascorbate (ρ = 0.67, p < 0.001) and 4-Hydroxynonenal (ρ = 0.43, p < 0.001). These data indicate that age-related increases in respiratory tract copper concentrations contribute to elevated levels of oxidative stress at the air–lung interface independently of respiratory disease.

BACKGROUND: In COPD, the balance between matrix metalloproteinases (MMPs) and their natural inhibitors [tissue inhibitors of metalloproteinases (TIMPs)] is shifted towards excessive degradation, reflected in bronchoalveolar lavage (BAL) as increased MMP concentrations. Because of their critical role in lung homeostasis, MMP activity is tightly regulated, but to what extent this regulation occurs through epigenetic mechanisms remains unknown.

METHODS: To explore the interplay between MMPs, TIMPs, and DNA methylation (DNAm) we (1) analysed MMP-9, -12, and TIMP-1 concentrations in BAL fluid, and profiled DNAm in BAL cells from 18 COPD and 30 control subjects, (2) estimated protein-COPD relationships using multivariable regression, (3) identified protein quantitative trait methylation loci (pQTMs) with COPD as a potential modifier in a separate interaction model, and (4) integrated significant interactions with a previous COPD GWAS meta-analysis.

RESULTS: COPD was associated with higher levels of BAL MMP-12 (p = 0.016) but not with MMP-9 or TIMP-1. Further examination of MMP-12 identified association with DNAm at 34 loci (pQTMs), with TGFBR2 (p = 2.25 × 10^-10) and THBS4 (p = 1.11 × 10^-9) among the top ten pQTM genes. The interaction model identified 66 sites where the DNAm-MMP-12 association was significantly different in COPD compared to controls. Of these, one was colocalized with SNPs previously associated with COPD.

CONCLUSIONS: Our findings indicate that airway MMP-12 may partially be regulated by epigenetic mechanisms and that this regulation is disrupted in COPD. Furthermore, integration with COPD GWAS data suggests that this dysregulation is influenced by a combination of environmental factors, disease processes, and genetics, with the latter potentially playing a lesser role.

Harmful effects of mechanical ventilation with large tidal volumes, volutrauma, may contribute much to diffuse acute lung injury. Extracellular vesicles have been noted in the context of vital organ injury. We hypothesized that extracellular vesicles from acutely injured lung can be found in both lung and blood. In a two-hit experimental porcine model, we tested if extracellular vesicles could be detected in bronchoalveolar lavage fluid and in plasma over a six-hour period of large tidal volume ventilation after surfactant depletion. After 2 hours of volutrauma, bronchoalveolar lavage fluid showed increased levels of extracellular vesicles containing nucleic acids (stained by SYTO 13) and those positive for both SYTO 13 and HMGB1. No such increase was detected in plasma at any timepoint during the six-hour experiments. This shows that nucleic acid-containing extracellular vesicles appear to be involved in progression of lung injury, possibly indicating cellular damage, but their potential to serve as diagnostic biomarkers of acute lung injury progression, based on plasma sampling, and in the very early phase, is not confirmed by these findings.

Objectives: There is a lack of knowledge about whether occupational exposures increase the risk of emphysema, especially in never-smokers. Our objective was to determine if occupational exposures are associated with emphysema and impaired diffusing capacity.

Methods: In the Swedish CArdioPulmonary bioImage Study (SCAPIS), persons from the general population aged 50–64 answered a questionnaire and underwent CT of the lung as well as assessment of the diffusing capacity of their lungs for carbon monoxide (DLCO), presented as DLCO<lower limit of normal (LLN). Emphysema was defined as emphysema in any part of the lungs. Occupational exposures were assessed by a job exposure matrix based on longest held job. ORs with 95% CIs were calculated using logistic multivariable models.

Results: In this cross-sectional study (27370 persons including 13981 never-smokers), occupational exposure to inorganic dust was associated with emphysema (OR 1.25, 95% CI 1.07 to 1.47), also among never-smokers, (OR 1.46, 95% CI 1.00 to 2.11). There were associations with DLCO<LLN for occupational exposure to inorganic dust and vapour and gases. With all exposures in the same model, inorganic dust was associated with emphysema (OR 1.30, 95% CI 1.08 to 1.57), and vapour and gases were associated with DLCO<LLN (OR 1.17, 95% CI 1.00 to 1.38). In those with emphysema and impaired DLCO, there was an association with inorganic dust (OR 1.65, 95% CI 1.20 to 2.28), also among never-smokers (OR 3.79, 95% CI 1.35 to 10.63).

Conclusions: Occupational exposures to inorganic dust are associated with emphysema. The association is stronger in those with the combination of emphysema and impaired DLCO indicating serious exposure effects in the alveoli.

BACKGROUND: Low lung function has been consistently associated with increased cardiovascular disease (CVD) risk, with emerging evidence suggesting a potential causal relationship. However, underlying biological mechanisms remain unclear. AIM: To investigate relationships between CVD-associated plasma proteins and lung function.

METHODS: We analysed plasma protein profiles in two Swedish population-based cohorts: the Swedish CArdioPulmonary bioImage Study (SCAPIS) (n = 4,982, mean age 57.6 years) as the discovery cohort and the SCAPIS pilot study (n = 1,054, mean age 57.7 years) for replication. Multiple linear regression models were used to assess associations between 92 CVD-associated proteins and z-scores of FEV1, FVC, and FEV1/FVC, adjusting for known confounders. P-values were corrected using the Benjamini-Hochberg method (5% FDR). Significantly associated proteins were validated in the replication cohort. R

ESULTS: A total of 69 proteins were associated with FEV1, 57 with FVC, and 9 with FEV1/FVC. Several inflammatory proteins and adipokines, including leptin, interleukin-6, fatty acid-binding protein (adipocyte), were consistently linked to lower lung function. Leptin had the strongest negative association (FEV1: β = -0.50, 95 % CI: [-0.69, -0.31], p < 0.001; FVC: β = -0.52, 95 % CI: [-0.68, -0.35], p < 0.001 per-SD increase).

CONCLUSIONS: Multiple CVD-associated proteins, mainly reflecting inflammatory and metabolic processes, were associated with reduced FEV1 and FVC, supporting a link between systemic inflammation, adipokine metabolism and impaired lung function. Leptin had the strongest association, suggesting that its effects on lung function may extend beyond adiposity. Further research is needed to clarify the mechanisms driving these associations and to assess whether these proteins could serve as early biomarkers or intervention targets.

Background: Preserved ratio impaired spirometry (PRISm) is a spirometry pattern of interest regarding incident airflow obstruction and higher mortality risk. We applied a proteomic approach to gain more insight into the biological mechanisms associated with PRISm.

Methods: From the population-based Swedish Cardiopulmonary Bioimage Study (SCAPIS), participants in the Main (n=4835) and Pilot (n=1054) studies, were included as discovery and replication cohorts. The lower limit of normal (LLN) of post-bronchodilator forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC was defined as the fifth percentile in healthy, never-smoking SCAPIS participants. Participants were subdivided into five groups: reference: FEV1/FVC⩾LLN and FEV1⩾LLN and FVC⩾LLN (n=4084)); mild chronic airflow limitation (CAL): FEV1/FVC<LLN and FEV1⩾LLN (n=278); moderate–severe CAL: FEV1/FVC<LLN and FEV1<LLN (n=170); restrictive spirometric pattern (RSP): FEV1/FVC ⩾LLN and FVC<LLN (n=238); and PRISm: FEV1/FVC⩾LLN and FEV1<LLN (n=238). Proximity extension assays were used to measure 168 proteins. The associations of each standardised protein were assessed with each study group by multiple linear regression models, adjusting for age, sex, body mass index (BMI), smoking, physical activity and study centres, and corrected for multiple testing to control for a false discovery rate of 5%.

Results: Eight proteins were associated with PRISm and replicated: tumour necrosis factor receptor superfamily member 10A, interleukin-6, paraoxonase 3 (negative association), renin, urokinase plasminogen activator surface receptor (U-PAR), E-selectin, matrix metalloproteinase 7 and chitinase-3-like protein 1. Interleukin-6 and U-PAR were also associated with moderate–severe CAL and E-selectin with RSP. In addition, five other proteins were associated with moderate–severe CAL and three with RSP.

Conclusion: Protein profile in PRISm differs from other spirometric patterns suggesting specific disease mechanisms.

Background: Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of the skin and internal organs, mostly affecting young and middle-aged women. Significant questions remain as to its pathogenesis, especially the triggers for the associated interstitial lung disease (SSc-ILD). We examined the extent to which SSc and SSc-ILD were related to oxidative stress and altered metal homeostasis at the air-lung interface.

Methods: In this case-control study, we recruited 20 SSc patients, of which 11 had SSc-ILD. Eighteen healthy individuals were recruited as age-matched healthy controls, for a total of 38 study participants. Low molecular weight antioxidants (ascorbate, urate and glutathione), metal transport and chelation proteins (transferrin and ferritin) and metals (Fe and Cu) concentrations, including a measure of the catalytically active metal pool, were determined in respiratory tract lining fluid (RTLF) collected by bronchoalveolar lavage from the SSc group and compared with healthy controls.

Results: In the SSc group, 14 individuals were of female sex (70%) and the median age was 57 years (range 35–75). We observed evidence of oxidative stress in the RTLFs of SSc patients, characterised by increased concentrations of glutathione disulphide (GSSG, P<0.01), dehydroascorbate (DHA, P<0.05) and urate (P<0.01). This was associated with elevated RTLF Fe (P=0.07) and Cu (P<0.001), and evidence of a catalytic metal pool, demonstrated by an enhanced rate of ascorbate oxidation in the recovered lavage fluid (p<0.01). Cu concentrations were significantly associated with the ascorbate depletion rate (r=0.76, P<0.001), and GSSG (r=0.38, P<0.05) and protein carbonyl (r=0.44, P<0.01) concentrations. Whilst these markers were all increased in SSc patients, we found no evidence for an association with SSc-ILD.

Conclusions: These data confirm the presence of oxidative stress in the airways of SSc patients and, for the first time, suggest that an underlying defect in metal homeostasis at the air-lung interface may play a role in disease progression.

Introduction: Flexible bronchoscopy is regarded as a safe examination and is commonly used in the diagnostic work-up for lung diseases, but is also important in pulmonary research. We aimed to investigate participants’ experiences when undergoing bronchoscopy in a research setting.

Methods: Participants were recruited from the Swedish CArdioPulmonary bioImage Study (SCAPIS). A subset from this cohort (n = 45, mean age 60.5 years, 20 with normal lung function and 25 with chronic obstructive pulmonary disease, COPD) was selected for bronchoscopy. The procedure was explained both orally and in writing during a pre-procedure visit. The information included premedication, monitoring, local anesthesia, airway sampling [bronchoalveolar lavage (BAL), bronchial wash, and mucosal biopsies], and urine and blood samples. Questionnaires pre- and/or post-procedure were used to assess experiences and health impacts.

Results: In general, participants found the bronchoscopy procedure acceptable and only a few (18%) found it unpleasant. A majority (80%) reported their experience to be much better or as expected. Almost all participants (93%) were very satisfied with the information provided. Topical anesthesia was seen as more unpleasant (20%) than airway sampling (11%). Notably, more women and participants with normal lung function reported BAL as unpleasant. After the procedure, chills, fever, and hemoptysis were reported, but no serious adverse events occurred. Increased cough and phlegm were noted.

Conclusion: The present study, conducted by experienced bronchoscopists and healthcare teams, demonstrates that a bronchoscopy in a research setting in well-informed participants with normal lung function or COPD was well-tolerated.

Rationale: Chronic obstructive pulmonary disease (COPD) includes respiratory symptoms and chronic airflow limitation (CAL). In some cases, emphysema and impaired diffusing capacity of the lung for carbon monoxide (DL_CO) are present, but characteristics and symptoms vary with smoking exposure.

Objective: To study the prevalence of CAL, emphysema, and impaired DL_CO in relation to smoking and respiratory symptoms in a middle-aged population.

Methods: We investigated 28,746 randomly invited individuals (52% women) aged 50-64 years across six Swedish sites. We performed spirometry, DL_CO testing, and high-resolution computed tomography and asked for smoking habits and respiratory symptoms. CAL was defined as post-bronchodilator forced expiratory volume in 1 second divided by forced vital capacity (FEV₁/FVC) < 0.7.

Results: The overall prevalence was 8.8% for CAL, 5.7% for impaired DL_CO (DL_CO < LLN), and 8.8% for emphysema, with a higher prevalence in current smokers than in ex-smokers and never-smokers. The proportion of never-smokers among those with CAL, emphysema, and impaired DL_CO was 32%, 19%, and 31%, respectively. Regardless of smoking habits, the prevalence of respiratory symptoms was higher among people with CAL and impaired DL_CO than those with normal lung function. Asthma prevalence in never-smokers with CAL was 14%. In this group, asthma was associated with lower FEV₁ and more respiratory symptoms.

Conclusions: In this large population-based study of middle-aged people, CAL and impaired DL_CO were associated with common respiratory symptoms. Self-reported asthma was not associated with CAL in never-smokers. Our findings suggest that CAL in never-smokers signifies a separate clinical phenotype that may be monitored and, possibly, treated differently from smoking-related COPD.

Rationale: Knowledge about the clinical importance of patient-reported outcome measures (PROMs) in severe asthma is limited.

Objectives: To assess whether and to what extent asthma exacerbations affect changes in PROMS over time and asthma-specific PROMs can predict exacerbations in adult patients with severe asthma in usual care.

Methods: Data of 421 patients with severe asthma (62% female; mean age 51.9 ± 13.4 years; mean FEV1 67.5 ± 21.3%pred) from the U-BIOPRED cohort were analyzed. The included PROMs were: Asthma Control Questionnaire (ACQ5); Asthma Quality of Life Questionnaire (AQLQ); Hospital Anxiety and Depression scale (HADS); Epworth Sleepiness Scale (ESS); Medication Adherence Report Scale (MARS); Sino-Nasal Outcomes Test (SNOT20). Participants were assessed at baseline and after 12–18 months of usual care.

Results: PROMs showed very weak to weak correlations with clinical characteristics such as age, body mass index, FEV1, FeNO and eosinophilic cell count. Patients presenting no exacerbations during follow-up showed a statistically significant improvement in all PROMs (except for MARS), whereas individuals experiencing > 2 exacerbations showed a deterioration. Baseline ACQ5 was a predictor of exacerbations with an AUC of 0.590 (95%CI 0.514–0.666).

Conclusions: The association of PROMs with clinical measures was poor in severe asthmatics. Moreover, PROMs were prone to changes in usual care, with exacerbations playing a key role. PROMs need to be systematically evaluated in severe asthma to improve clinical care based on specific patient’s needs.