Proposition 2, which requires that egg-laying hens be confined only in ways that allow these animals to lie down, stand up, fully extend their limbs and turn around freely, was passed by the voters of California in 2008. These new housing requirements were introduced in the USA and European Union without considering the potential impact of changes in layer hen housing on the health of poultry workers in the new facilities. Particles were collected from ambient air inside a large layer hen complex featuring separate barns with conventional battery caging, enriched caging, or 'free range' (aviary) housing during winter, spring, and summer seasons over one year. Toxicity of the particles was evaluated by analysis of inflammatory cell influx into lung lavage fluid after intratracheal instillation into mice. Capacity of the particles to elicit oxidative stress was evaluated using a macrophage cell line engineered with a reporter gene sensitive to nuclear factor κB activation. We observed similar pro-inflammatory and pro-oxidant effects of the particles collected from different types of barns and over different seasons, suggesting that standard industrial hygiene techniques for evaluating respirable particles in ambient air can adequately monitor worker risk. Based on particle concentrations found in ambient air in the barns, we can rank the facilities for worker exposure to particles as conventional caging (now banned) approximately equal to enriched caging (permitted under Proposition 2). Aviary housing is associated with increased exposure of workers to particulate matter and, therefore, to greater risk of allergic reactions and/or decreased respiratory function.

Alterations in arginine metabolism and accelerated formation of advanced glycation end-products (AGEs), crucial mechanisms in obesity-related asthma, can be modulated by glucagon-like peptide 1 (GLP-1). l-arginine dysregulation in obesity promotes inflammation and bronchoconstriction. Prolonged hyperglycemia, dyslipidemia, and oxidative stress leads to production of AGEs, that bind to their receptor (RAGE) further potentiating inflammation. By binding to its widely distributed receptor, GLP-1 blunts the effects of RAGE activation and arginine dysregulation. The GLP-1 pathway, while comprehensively studied in the endocrine and cardiovascular literature, is under-recognized in pulmonary research. Insights into GLP-1 and the lung may lead to novel treatments for obesity-related asthma.

Obesity is considered as a risk factor for COVID-19 with insulin resistance and increased production of inflammatory cytokines as likely mechanisms. Glucagon-like peptide-1 (GLP-1) agonists and inhaled nitric oxide are proposed therapeutic approaches to treat COVID-19 because of their broad anti-inflammatory effects. One approach that might augment GLP-1 levels would be dietary supplementation with L-arginine. Beyond cytokines, multiple studies have started to investigate the relationship between new-onset diabetes and COVID-19. In a posthoc analysis of a randomized, placebo-controlled human clinical trial of L-arginine supplementation in people with asthma and predominantly with obesity, the results showed that 12 weeks of continuous L-arginine supplementation significantly decreased the level of IL-21 (p = 0.02) and increased the level of insulin (p = 0.02). A high arginine level and arginine/ADMA ratio were significantly associated with lower CCL-20 and TNF-α levels. The study also showed that L-arginine supplementation reduces cytokine levels and improves insulin deficiency or resistance, both are two big risk factors for COVID-19 severity and mortality. Given its safety profile and ease of accessibility, L-arginine is an attractive potential therapeutic option that allows for a cost-effective way to improve outcomes in patients. An expedition of further investigation or clinical trials to test these hypotheses is needed.

Background

Bronchial thermoplasty is a nonpharmacological, device-based treatment option for a specific population of severe asthmatic subjects, but the underlying mechanisms are largely unknown. The purpose of this study is to identify potential altered pathways by bronchial thermoplasty using a transcriptomic approach.

Methods

Patients undergoing bronchial thermoplasty were recruited to the study, and a bronchial brushing sample was obtained before each bronchial thermoplasty session and sent for RNA sequencing. A variance component score test was performed to identify those genes whose expression varied after bronchial thermoplasty sessions. Differential gene expression meta-analysis of severe asthmatic subjects versus controls was performed using public repositories. Overlapping genes were included for downstream pathway and network analyses.

Results

12 patients were enrolled in our study. A total of 133 severe asthma cases and 107 healthy controls from the public repositories were included in the meta-analysis. Comparison of differentially expressed genes from our study patients with the public repositories identified eight overlapping genes: AMIGO2, CBX7, NR3C2, SETBP1, SHANK2, SNTB1, STXBP1 and ZNF853. Network analysis of these overlapping genes identified pathways associated with neurophysiological processes.

Conclusion

We have shown that bronchial thermoplasty treatment alters several gene networks that are important in asthma pathogenesis. These results potentially elucidate the disease-modifying mechanisms of bronchial thermoplasty and provide several targets for further investigation.

Asthma is a complex syndrome that affects an estimated 26 million people in the United States but gaps exist in the recognition and management of asthmatic subgroups. This article proposes alternative approaches for future treatments of adult obese asthmatics who do not respond to standard controller therapies, drawing parallels between seemingly disparate therapeutics through their common signaling pathways. How metformin and statins can potentially improve airway inflammation is described and supplements are suggested. A move toward more targeted therapies for asthma subgroups is needed. These therapies address asthma and the comorbidities that accompany obesity and metabolic syndrome to provide the greatest therapeutic potential.

Positive-pressure ventilation results in ventilator-induced lung injury, and few therapeutic modalities have been successful at limiting the degree of injury to the lungs. Understanding the primary drivers of ventilator-induced lung injury will aid in the development of specific treatments to ameliorate the progression of this syndrome. There are conflicting data for the role of neutrophils in acute respiratory distress syndrome pathogenesis. Here, we specifically examined the importance of neutrophils as a primary driver of ventilator-induced lung injury in a mouse model known to have impaired ability to recruit neutrophils in previous models of inflammation. We exposed Duoxa^+/+ and Duoxa^-/- mice to low- or high-tidal volume ventilation with or without positive end-expiratory pressure (PEEP) and recruitment maneuvers for 4 hours. Absolute neutrophils in BAL fluid were significantly reduced in Duoxa^-/- mice compared with Duoxa^+/+ mice (6.7 cells/μl; 16.4 cells/μl; P = 0.003), consistent with our hypothesis that neutrophil translocation across the capillary endothelium is reduced in the absence of DUOX1 or DUOX2 in response to ventilator-induced lung injury. Reduced lung neutrophilia was not associated with a reduction in overall lung injury in this study, suggesting that neutrophils do not play an important role in early features of acute lung injury. Surprisingly, Duoxa^-/- mice exhibited significant hypoxemia, as measured by the arterial oxygen tension/fraction of inspired oxygen ratio and arterial oxygen content, which was out of proportion with that seen in the Duoxa^+/+ mice (141, 257, P = 0.012). These findings suggest a role for dual oxidases to limit physiologic impairment during early ventilator-induced lung injury.

Respiratory viral infections such as human rhinovirus (HRV) can lead to substantial morbidity and mortality, especially in people with underlying lung diseases such as asthma and COPD. One proposed strategy to detect viral infections non-invasively is by volatile organic compound (VOC) assessment via analysis of exhaled breath. The epithelial cells are one of the most important cell lines affected during respiratory infections as they are the first line of pathogen defense. Efforts to discover infection-specific biomarkers can be significantly aided by understanding the VOC emanations of respiratory epithelial cells. Here we test the hypothesis that VOCs obtained from the headspace of respiratory cell culture will differentiate healthy cells from those infected with HRV. Primary human tracheobronchial cells were cultured and placed in a system designed to trap headspace VOCs. HRV-infected cells were compared to uninfected control cells. In addition, cells treated with heat-killed HRV and poly(I:C), a TLR3 agonist, were compared to controls. The headspace was sampled with solid-phase microextraction fibers and VOCs were analyzed by gas chromatography/mass spectrometry. We determined differential expression of compounds such as aliphatic alcohols, branched hydrocarbons, and dimethyl sulfide by the infected cells, VOCs previously associated with oxidative stress and bacterial infection. We saw no major differences between the killed-HRV, poly(I:C), and control cell VOCs. We postulate that these compounds may serve as biomarkers of HRV infection, and that the production of VOCs is not due to TLR3 stimulation but does require active viral replication. Our novel approach may be used for the in vitro study of other important respiratory viruses, and ultimately it may aid in identifying VOC biomarkers of viral infection for point-of-care diagnostics.

Argininosuccinate synthase 1 (ASS1) serves as a critical enzyme in arginine biosynthesis; however, its role in interstitial lung diseases, particularly idiopathic pulmonary fibrosis (IPF), remains largely unknown. This study aims at characterization and targeting of ASS1 deficiency in pulmonary fibrosis. We find that ASS1 was significantly decreased and inversely correlated with fibrotic status. Transcriptional downregulation of ASS1 was noted in fibroblastic foci of primary lung fibroblasts isolated from IPF patients. Genetic manipulations of ASS1 studies confirm that ASS1 expression inhibited fibroblast cell proliferation, migration, and invasion. We further show that the hepatocyte growth factor receptor (Met) receptor was activated and acted upstream of the Src-STAT3 axis signaling in ASS1-knockdown fibroblasts. Interestingly, both arginine-free conditions and arginine deiminase treatment were demonstrated to kill fibrotic fibroblasts, attenuated bleomycin-induced pulmonary fibrosis in mice, as well as synergistically increased nintedanib efficacy. Our data suggest ASS1 deficiency as a druggable target and also provide a unique therapeutic strategy against pulmonary fibrosis.

The human respiratory tract releases volatile metabolites into exhaled breath that can be utilized for noninvasive health diagnostics. To understand the origin of this metabolic process, our group has previously analyzed the headspace above human epithelial cell cultures using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). In the present work, we improve our model by employing sorbent-covered magnetic stir bars for headspace sorptive extraction (HSSE). Sorbent-coated stir bar analyte recovery increased by 52 times and captured 97 more compounds than SPME. Our data show that HSSE is preferred over liquid extraction via stir bar sorptive extraction (SBSE), which failed to distinguish volatiles unique to the cell samples compared against media controls. Two different cellular media were also compared, and we found that Opti-MEM® is preferred for volatile analysis. We optimized HSSE analytical parameters such as extraction time (24 h), desorption temperature (300 °C) and desorption time (7 min). Finally, we developed an internal standard for cell culture VOC studies by introducing 842 ng of deuterated decane per 5 mL of cell medium to account for error from extraction, desorption, chromatography and detection. This improved model will serve as a platform for future metabolic cell culture studies to examine changes in epithelial VOCs caused by perturbations such as viral or bacterial infections, opening opportunities for improved, noninvasive pulmonary diagnostics.

The respiratory system is continuously exposed to variety of biological and chemical irritants that contain reactive oxygen species, and these are well known to cause oxidative stress responses in lung epithelial cells. There is a clinical need to identify biomarkers of oxidative stress which could potentially support early indicators of disease and health management. To identify volatile biomarkers of oxidative stress, we analyzed the headspace above human bronchial epithelial cell cultures (HBE1) before and after hydrogen peroxide (H₂O₂) and cigarette smoke extract (CSE) exposure. Using stir bar and headspace sorptive extraction-gas chromatography-mass spectrometry, we searched for volatile organic compounds (VOC) of these oxidative measures. In the H₂O₂ cell peroxidation experiments, four different H₂O₂ concentrations (0.1, 0.5, 10, 50 mM) were applied to the HBE1 cells, and VOCs were collected every 12 h over the time course of 48 h. In the CSE cell peroxidation experiments, four different smoke extract concentrations (0%, 10%, 30%, 60%) were applied to the cells, and VOCs were collected every 12 h over the time course of 48 h. We used partial-least squares (PLS) analysis to identify putative compounds from the mass spectrometry results that highly correlated with the known applied oxidative stress. We observed chemical emissions from the cells that related to both the intensity of the oxidative stress and followed distinct time courses. Additionally, some of these chemicals are aldehydes, which are thought to be non-invasive indicators of oxidative stress in exhaled human breath. Together, these results illustrate a powerful in situ cell culture model of oxidative stress that can be used to explore the putative biological genesis of exhaled breath biomarkers that are often observed in human clinical studies.