DNA methylome-based validation of induced sputum as an effective protocol to study lung immunity : construction of a classifier of pulmonary cell types

Flow cytometry is a classical approach used to define cell types in peripheral blood. While DNA methylation signatures have been extensively employed in recent years as an alternative to flow cytometry to define cell populations in peripheral blood, this approach has not been tested in lung-derived samples. Here, we compared bronchoalveolar lavage with a more cost-effective and less invasive technique based on sputum induction and developed a DNA methylome-based algorithm that can be used to deconvolute the cell types in such samples. We analysed the DNA methylome profiles of alveolar macrophages and lymphocytes cells isolated from the pulmonary compartment. The cells were isolated using two different methods, sputum induction and bronchoalveolar lavage. A strong positive correlation between the DNA methylome profiles of cells obtained with the two isolation methods was found. We observed the best correlation of the DNA methylomes when both isolation methods captured cells from the lower parts of the lungs. We also identified unique patterns of CpG methylation in DNA obtained from the two cell populations, which can be used as a signature to discriminate between the alveolar macrophages and lymphocytes by means of open-source algorithms. We validated our findings with external data and obtained results consistent with the previous findings. Our analysis opens up a new possibility to identify different cell populations from lung samples and promotes sputum induction as a tool to study immune cell populations from the lung.Funding Agencies|Forskningsradet Sydostra Sverige [FORSS-932096]; Swedish Research CouncilSwedish Research CouncilEuropean Commission [2015-02593, 2018-02961]; Swedish Heart Lung FoundationSwedish Heart-Lung Foundation [20150709, 20180613]; Medical Infection and Inflammation Center (MIIC) at Linkoping University; Forskningsradet i Sydostra Sverige [FORSS-932096]; Hjart-Lungfonden [20150709, 20180613]; VetenskapsradetSwedish Research Council [2015-02593, 2018-02961]</p

Isolating and culturing of sputum macrophages: A potential ex vivo/in vitro model

Purpose: This paper aimed to test whether induced sputum samples acquired from human volunteers could be used to isolate and culture airway macrophages for in vitro exposures. This was assessed in terms of the culturing success rate, culture purity, viability and responsiveness of cultured cells. Materials and methods: The isolation and culturing procedure was performed over three days. On Day 1, induced sputum samples were obtained, processed and seeded in culture wells. Differential cell counts and viability tests were performed to allow for calculation of viable macrophage numbers and appropriate sample dilution. After a 1 h rest, seeded wells were washed to remove non-adherent cells, resulting in macrophage isolation. Then, cells rested overnight (Day 1–Day 2), before in vitro exposure for 2–24 h (Day 2–Day 3). The criteria for progressing into the culturing procedure was cell viability >40% and total cell number >106. Successful culturing was evaluated based on cell attachment (N = 40). Culture purity by differential cell analysis and viability was monitored during culturing (N = 4–8). Macrophage responsivity was assessed by measurement of inflammatory cytokine gene expression (N = 4) and cytokine levels (N = 6) following in vitro exposure to lipopolysaccharide (LPS) (2–24 h) and live bacteria (S. aureus) (4h). Results: Overall, 88% (35/40) of the samples acquired were suitable for isolation, and 80% (32/40) were successfully progressed through the 2–3 day culturing protocol. Macrophage purity (88%) and viability (85%) were adequate. Moreover, cultured macrophages were responsive to in vitro stimulation with LPS and viable S. aureus showing positive mRNA responses for TNFα, IL-1β and IL-8 and release of IL-1β, respectively. Conclusion: Sputum macrophage isolation by plate adherence and subsequent culturing of sputum macrophages was successfully performed and represents a promising in vitro model for examination of airway macrophage behavior

The Role of Airway Inflammation and Bronchial Hyperresponsiveness in Athlete's Asthma

Purpose Asthma is frequently reported in endurance athletes. The aim of the present study was to assess the long-term airway inflammatory response to endurance exercise in high-level athletes with and without asthma. Methods In a cross-sectional design, 20 asthmatic athletes (10 swimmers and 10 cross-country skiers), 19 athletes without asthma (10 swimmers and 9 cross-country skiers), and 24 healthy nonathletes completed methacholine bronchial challenge, lung function tests, and sputum induction on two separate days. All athletes competed on a national or international level and exercised ≥10 h·wk-1. The nonathletes exercised ≤5 h·wk-1 and reported no previous lung disease. Bronchial hyperresponsiveness (BHR) was defined as a methacholine provocation dose causing 20% decrease in the forced expiratory volume in 1 s of ≤8 μmol. Results BHR was present in 13 asthmatic athletes (62%), 11 healthy athletes (58%), and 8 healthy nonathletes (32%), and the prevalence differed among groups (P = 0.005). Sputum inflammatory and epithelial cell counts did not differ between groups and were within the normal range. Median (25th to 75th percentiles) sputum interleukin-8 was elevated in both asthmatic (378.4 [167.0-1123.4]) and healthy (340.2 [175.5-892.4]) athletes as compared with healthy nonathletes (216.6 [129.5-314.0], P = 0.02). No correlations were found between provocation dose causing 20% decrease and sputum cell counts. Conclusion Independent of asthma diagnosis, a high occurrence of BHR and an increased sputum interleukin-8 were found in athletes as compared with nonathletes. Airway inflammation or epithelial damage was not related to BHR

A role for the terminal C5-C9 complement pathway in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease characterized by damage to the alveolar epithelium, leading to fibrosis and excessive accumulation of extracellular matrix in the interstitium of the lung. In the present study we performed high-resolution proteomic profiling of bronchoalveolar lavage (BAL) from IPF patients and controls, and found that the complement pathway was highly upregulated in IPF. The proteins C5, C6, C7, C8, and C9, all of which are part of the complement end product, TCC, were all upregulated. We also found that TCC levels were increased in plasma among IPF patients compared to controls, after adjustment for age, sex and BMI [mean (SD) 0.62 (0.24) vs. 0.33 (0.10), p = 0.031]. These findings suggest a role for the complement system in the pathogenesis of IPF

Comparison of different reference values for lung function: implications of inconsistent use among centers

Abstract Background For interpretation of pulmonary function tests (PFTs), reference values based on sex, age, height and ethnicity are needed. In Norway, the European Coal and Steel Community (ECSC) reference values remain widely used, in spite of recommendations to implement the more recent Global Lung Function Initiative (GLI) reference values. Objective To assess the effects of changing from ECSC to GLI reference values for spirometry, DLCO and static lung volumes, using a clinical cohort of adults with a broad range in age and lung function. Methods PFTs from 577 adults (18–85 years, 45% females) included in recent clinical studies were used to compare ECSC and GLI reference values for FVC, FEV1, DLCO, TLC and RV. Percent predicted and lower limit of normal (LLN) were calculated. Bland-Altman plots were used to assess agreement between GLI and ECSC % predicted values. Results In both sexes, GLI % predicted values were lower for FVC and FEV1, and higher for DLCO and RV, compared to ECSC. The disagreement was most pronounced in females, with mean (SD) difference 15 (5) percent points (pp) for DLCO and 17 (9) pp for RV (p < 0.001). With GLI, DLCO was below LLN in 23% of the females, with ECSC in 49% of the females. Conclusions The observed differences between GLI and ECSC reference values are likely to entail significant consequences with respect to criteria for diagnostics and treatment, health care benefits and inclusion in clinical trials. To ensure equity of care, the same reference values should be consistently implemented across centers nationwide

Endotoxin and Hydrogen Sulphide Exposure and Effects on the Airways Among Waste Water Workers in Sewage Treatment Plants and Sewer Net System

Background: The purpose of this study is to investigate whether airborne exposure to endotoxins, hydrogen sulphide (H2S), and inhalable particles negatively impacts the respiratory system and inflammatory blood proteins in sewage plant and sewer net system workers and, further, to determine dose-response associations between exposure and health outcomes. Methods: In total, 148 waste water workers (WWWs) from urban and rural sewage plants and the sewer net system participated. One hundred and twenty-one workers were exposed to sewage, 46 from sewage plants and 75 from the sewer net system. Twenty-seven workers were characterized as little or not exposed and served as an internal reference group. Personal inhalable samples were analysed for endotoxins (Limulus assay), particle dust (gravimetrically) and Salmonella and Yersinia spp. (polymerase chain reaction method, PCR). Levels of H2S were measured using personal electro chemical sensors. Intercellular adhesion molecule 1 (ICAM-1), interleukin 8 (IL-8), surfactant protein D (SP-D), club cell protein 16 (CC16), and macrophage inflammatory protein (MIP) were determined by enzyme-linked immunosorbent assay and C-reactive protein (CRP) by an HS-MicroCRP assay in blood samples. Results: Workers in sewage plants were exposed to significantly higher levels of endotoxins compared to workers in the sewer net system [median 55 EU m−3 (4–262 EU m−3) and median 27 EU m−3 (1–304 EU m−3), respectively]. The estimated H2S index showed higher values when working in the sewer net system [median 3.1 (0.5–78.1)] compared to workers at the sewage plants [median 1.3 (0.5–9.3)], and the most excessive exposure was collecting sewage from cesspools (273 p.p.m.). No viable airborne Salmonella and Yersinia spp. were detected. The exposed workers had significantly higher CRP compared to the referents [1.2 µg ml−1 (0.1–19.0 µg ml−1) and 0.8 µg ml−1 (0.1–5.0 µg ml−1), respectively] and lower forced expiratory volume in 1 s (FEV1)% [92.6%, standard deviation (SD) 14.6 and 102.0%, SD 10.1, respectively], with numbers given as mean and SD. The serum concentration of CRP was significantly and negatively associated with FEV1% (β = −7.7, R2 = 0.05) and forced vital capacity % (β = −8.5, R2 = 0.08), and the serum concentration of ICAM-1 with the estimated exposure to H2S (β = −19.9, R2 = 0.07). Conclusion: Despite moderate levels of endotoxin and H2S exposure, the results indicate an impact of these agents on lung function and the adhesion molecule ICAM-1, and a low-grade systemic inflammation was indicated in increased levels of CRP

Endotoxin and Hydrogen Sulphide Exposure and Effects on the Airways Among Waste Water Workers in Sewage Treatment Plants and Sewer Net System

Background: The purpose of this study is to investigate whether airborne exposure to endotoxins, hydrogen sulphide (H2S), and inhalable particles negatively impacts the respiratory system and inflammatory blood proteins in sewage plant and sewer net system workers and, further, to determine dose-response associations between exposure and health outcomes. Methods: In total, 148 waste water workers (WWWs) from urban and rural sewage plants and the sewer net system participated. One hundred and twenty-one workers were exposed to sewage, 46 from sewage plants and 75 from the sewer net system. Twenty-seven workers were characterized as little or not exposed and served as an internal reference group. Personal inhalable samples were analysed for endotoxins (Limulus assay), particle dust (gravimetrically) and Salmonella and Yersinia spp. (polymerase chain reaction method, PCR). Levels of H2S were measured using personal electro chemical sensors. Intercellular adhesion molecule 1 (ICAM-1), interleukin 8 (IL-8), surfactant protein D (SP-D), club cell protein 16 (CC16), and macrophage inflammatory protein (MIP) were determined by enzyme-linked immunosorbent assay and C-reactive protein (CRP) by an HS-MicroCRP assay in blood samples. Results: Workers in sewage plants were exposed to significantly higher levels of endotoxins compared to workers in the sewer net system [median 55 EU m−3 (4–262 EU m−3) and median 27 EU m−3 (1–304 EU m−3), respectively]. The estimated H2S index showed higher values when working in the sewer net system [median 3.1 (0.5–78.1)] compared to workers at the sewage plants [median 1.3 (0.5–9.3)], and the most excessive exposure was collecting sewage from cesspools (273 p.p.m.). No viable airborne Salmonella and Yersinia spp. were detected. The exposed workers had significantly higher CRP compared to the referents [1.2 µg ml−1 (0.1–19.0 µg ml−1) and 0.8 µg ml−1 (0.1–5.0 µg ml−1), respectively] and lower forced expiratory volume in 1 s (FEV1)% [92.6%, standard deviation (SD) 14.6 and 102.0%, SD 10.1, respectively], with numbers given as mean and SD. The serum concentration of CRP was significantly and negatively associated with FEV1% (β = −7.7, R2 = 0.05) and forced vital capacity % (β = −8.5, R2 = 0.08), and the serum concentration of ICAM-1 with the estimated exposure to H2S (β = −19.9, R2 = 0.07). Conclusion: Despite moderate levels of endotoxin and H2S exposure, the results indicate an impact of these agents on lung function and the adhesion molecule ICAM-1, and a low-grade systemic inflammation was indicated in increased levels of CRP