GOLD Focuses on Factors Other Than Smoking in New Report on COPD
While still taking the key pathogenic role of tobacco smoking into account, the 2023 GOLD report acknowledges other factors that play a role in the development of the disease.
“The updated definition focuses on patient characteristics that then allows us to go into etiology and diagnostic criteria in more detail separately,” explained MeiLan Han, MD, chief of pulmonary and critical care medicine at the University of Michigan and a co-author of the report. “This is important because we now can better emphasize all of the factors that can contribute to COPD beyond tobacco exposure.”
For example, the authors note that in low and middle-income countries, which together contribute to more than 85% of COPD cases worldwide, factors other than smoking may be more important. These include environmental factors, lung development and aging, socioeconomic status, and asthma and airway hyperreactivity.
The proposed definition states that COPD is “a heterogeneous lung condition characterized by chronic respiratory symptoms (dyspnea, cough, expectoration, exacerbations) due to abnormalities of the airways (bronchitis, bronchiolitis) and/or alveoli (emphysema) that cause persistent, often progressive, airflow obstruction.”
In addition to revising its stance on factors associated with COPD, the report suggests five new COPD categories and how they can be used:
- Early COPD: To be used only in an experimental setting when discussing the initial biological mechanisms that will eventually lead to COPD rather than at the time when initial symptoms become apparent.
- Mild COPD: To be used only to describe the severity of airflow obstruction measured spirometrically.
- Young COPD: To be used to describe COPD in patients aged 20-50 years old.
- Pre-COPD: To identify individuals of any age with respiratory symptoms and/or structural and/or functional abnormalities but no evidence of airflow obstruction.
- PRISm: To describe individuals with no airflow obstruction but abnormal spirometry.
The report was published by the American Journal of Respiratory and Critical Care Medicine. Read More
Sympathetic Nerves in the Lungs May Play a Role in the Development of Allergic Asthma
Researchers from Massachusetts General Hospital have linked allergic asthma to sympathetic nerves in the lungs. They believe the finding could lead to a new treatment for allergic asthma in children and adults.
The study was conducted in a mouse model and involved tracking allergen-specific immune cells called T helper 2 resident memory cells (Th2-TRMs), which are known to be the central mediator of recurrent allergic inflammation in the lungs.
Through their experiments, the investigators found that following allergen exposure in newborns, sympathetic nerves in the lungs, which produce dopamine, are found in close proximity to certain T helper 2 cells. When dopamine from those nerves binds to DRD4 receptors on the T helper 2 cells, the cells are more prone to be transformed into Th2-TRMs, which leads to the production of cytokines.
When the researchers blocked dopamine from binding to the T helper 2 cells following allergen exposure in newborns, the transformation of T helper 2 cells into Th2-TRMs was reduced. What’s more, when the same mice encountered the same allergen during adulthood, lung inflammation was alleviated.
Since human lungs are similarly innervated by dopaminergic nerves in early postnatal life, the authors believe the dopamine-DRD4 axis may provide a therapeutic target to modify allergic asthma progression from childhood to adulthood.
The study was supported by the National Institutes of Health and published by the Journal of Allergy & Clinical Immunology. Read More
Vaping CBD More Harmful to the Lungs than Vaping Nicotine
Vaping cannabidiol (CBD) is worse than vaping nicotine, report researchers from Roswell Park Comprehensive Cancer Center.
Their study, which is the first to compare the pulmonary effects of vaping nicotine and vaping CBD, involved in vivo models and in vitro cultures of human cells, which were exposed to filtered air, nicotine aerosols, or CBD aerosols for two weeks. The findings included –
- The number and severity of focal lesions in the lung were greater after inhalation of CBD aerosols than nicotine aerosols.
- The enzyme myeloperoxidase (MPO), which promotes inflammation and damage to lung cells, showed significantly greater activity following exposure to CBD aerosol than nicotine aerosol.
- Inhalation of CBD aerosols resulted in greater inflammatory changes and higher oxidative stress in the lung.
- Exposure to CBD aerosols killed purified human neutrophils at a higher rate than nicotine aerosols, 44.5% vs. 21%.
- CBD aerosols were more toxic to cultures of human small airway epithelial cells and disrupted the integrity of the lung epithelial barrier.
- Inhalation of CBD aerosols resulted in significantly lower numbers of pulmonary interstitial macrophages compared with inhalation of nicotine aerosols, 11,460 cells in CBD-vape vs. 27,727 cells in nicotine-vape.
“Our findings suggest that vaping cannabis may not only cause significant lung injury, but can also increase susceptibility to respiratory infections, lead to poor responses to prophylactic vaccinations, or cause worsening of symptoms in patients with underlying pulmonary inflammatory disease,” said study author Yasmin Thanavala, PhD.
Dr. Thanavala suggests health care providers not only ask their patients if they vape, but what they vape.
The study was published by Thorax. Read More
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