Nav: Home

Unusual lung structures may raise risk of pulmonary disease

February 06, 2018

The internal anatomy of our lungs is surprisingly variable, and some of those variations are associated with a greater risk of chronic obstructive pulmonary disease (COPD), a new study led by researchers at McGill University and the Columbia University Irving Medical Center has found.

The variations occur in large airway branches in the lower lobes of the lungs and are readily detected with standard CT scans. The findings suggest that people with certain variations might, in the future, need more personalized treatments.

COPD is a progressive lung disease that causes airway inflammation, makes breathing more difficult, and is the fourth leading cause of death in the world. COPD usually occurs in people with a history of smoking, commonly after they have quit smoking, but is increasingly recognized in those who have never smoked.

Benjamin Smith, an assistant professor in McGill's Department of Medicine and the study's first author, noticed that variations in the large airways of lungs had been reported in old autopsy studies. So he and the other researchers set out to see how common those variations are in the general population, and if they were associated with COPD.

For the study, the researchers examined CT scans from more than 3,000 people in the Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study.

Extra and missing branches

"We found that central airway branches of the lungs, which are believed to form early in life, do not follow the textbook pattern in one quarter of the adult population and these non-textbook variations in airway branches are associated with higher COPD prevalence among older adults," said Smith, who is also a scientist from the Translational Research in Respiratory Diseases Program at the Research Institute of the McGill University Health Centre (RI-MUHC). "Interestingly, one of the airway branch variants was associated with COPD among smokers and non-smokers. The other was associated with COPD, but only among smokers."

About 16 percent of people possess an extra airway branch in the lung, about 6 percent are missing a branch, and another 4 percent have a combination of variants or other patterns. The results were published online Jan. 16 in the Proceedings of the National Academy of Sciences.

"The amount of lung variation high up in the airway tree was quite a surprise to us," says R. Graham Barr, MD, chief of general medicine at Columbia University Irving Medical Center and the study's senior author. "These changes are occurring at a branching level equivalent to your fingers-so it's like a quarter of us having four or six fingers instead of five."

People with an extra airway branch were 40 percent more likely to have COPD than people with standard anatomy. And people missing a specific airway branch were almost twice as likely to have COPD, but only if they smoked. The findings were replicated in a second study of almost 3,000 patients with and without COPD.

These airway tree variations are identifiable on low-dose screening lung CT scans, which are currently indicated clinically for lung cancer screening in older patients with a history of heavy smoking in the prior 15 years. Before CT scans are used outside of this group for the identification of airway variants in clinical practice, the study authors say more research will be needed to confirm that preventive or therapeutic interventions based on the presence of airway tree variations can improve patients' outcomes.

Quitting smoking remains best antidote

In the meantime, the researchers say they will be investigating another important finding -- this one around family history. Their study identified a common airway branch variation that occurs within families and is associated with COPD among non-smokers. Smith said while other developmental events that occur within families may be involved, his research team is looking into whether there is a genetic basis for this variant. "If proven," he said, "this would represent a novel mechanism of COPD among non-smokers."

Smith emphasized that for all the new findings, quitting smoking remains the best antidote to COPD, and smokers trying to quit should seek professional help, if necessary, to succeed.
-end-
About the study

The study, titled "Human Airway Branch Variation and Chronic Obstructive Pulmonary Disease," was published Jan. 16 ahead of print in Proceedings of the National Academy of Sciences.

DOI: http://www.pnas.org/cgi/doi/10.1073/pnas.1715564115

Other authors: Hussein Traboulsi (McGill Univ., RI-MUHC), John H.M. Austin (Columbia), Ani Manichaikul (Univ. of Virginia), Eric A. Hoffman (Univ. of Iowa), Eugene R. Bleecker (Univ. of Arizona), Wellington V. Cardoso (Columbia), Christopher Cooper (UCLA), David J. Couper (UNC-Chapel Hill), Stephen M. Dashnaw (Columbia), Jia Guo (Columbia), MeiLan K. Han (Univ. of Michigan), Nadia N. Hansel (Johns Hopkins), Emlyn W. Hughes (Columbia), David R. Jacobs Jr. (Univ. of Minnesota), Richard E. Kanner (Univ. of Utah), Joel D. Kaufman (Univ. of Washington), Eric Kleerup (UCLA), Ching-Long Lin (Univ. of Iowa), Kiang Liu (Northwestern), Christian M. Lo Cascio (Columbia), Fernando J. Martinez (Cornell Univ.), Jennifer N. Nguyen (Univ. of Virginia), Martin R. Prince (Cornell Univ.), Stephen Rennard (Univ. of Nebraska), Stephen S. Rich (Univ. of Virginia), Leora Simon (McGill Univ., RI-MUHC), Yanping Sun (Columbia), Karol E. Watson (UCLA), Prescott G. Woodruff (UCSF), and Carolyn J. Baglole (McGill Univ., RI-MUHC).

Financial support was provided by the National Institutes of Health, Research Institute of the McGill University Health Centre, and the Fonds de recherche du Québec - Santé (FRQS).

One co-author (EAH) is co-founder and shareholder in Vida Diagnostics, which was used to assess some, but not the main, lung measures in the study.

Contacts:

Cynthia Lee
McGill University
Media Relations Office
514-398-6754
cynthia.lee@mcgill.ca

Julie Robert
McGill University Health Centre, Communications
514-971-4747
julie.robert@muhc.mcgill.ca

McGill University

Related Smoking Articles:

Telomere length unaffected by smoking
A new study has surprised the medical world, finding that smoking does not shorten the length of telomeres -- a marker at the end of our chromosomes that is widely accepted as an indicator of aging.
Want to quit smoking? Partner up
Kicking the habit works best in pairs. That's the main message of a study presented today at EuroPrevent 2019, a scientific congress of the European Society of Cardiology (ESC).
Smoking and mortality in Asia
In this analysis of data from 20 studies conducted in China, Japan, South Korea, Singapore, Taiwan and India with more than 1 million participants, deaths associated with smoking continued to increase among men in Asia grouped by the years in which they were born.
Predictors of successfully quitting smoking among smokers registered at the quit smoking clinic at a public hospital in northeastern Malaysia
In the current issue of Family Medicine and Community Health, Nur Izzati Mohammad et al. consider how cigarette smoking is one of the risk factors leading to noncommunicable diseases such as cardiovascular and respiratory system diseases and cancer.
Restaurant and bar smoking bans do reduce smoking, especially among the highly educated
Smoking risk drops significantly in college graduates when they live near areas that have completely banned smoking in bars and restaurants, according to a new study in the American Journal of Epidemiology.
How the UK smoking ban increased wellbeing
Married women with children reported the largest increase in well-being following the smoking bans in the UK in 2006 and 2007 but there was no comparable increase for married men with children.
Smoking study personalizes treatment
A simple blood test is allowing Vanderbilt University Medical Center (VUMC) researchers to determine which patients should be prescribed varenicline (Chantix) to stop smoking and which patients could do just as well, and avoid side effects, by using a nicotine patch.
A biophysical smoking gun
While much about Alzheimer's disease remains a mystery, scientists do know that part of the disease's progression involves a normal protein called tau, aggregating to form ropelike inclusions within brain cells that eventually strangle the neurons.
A case where smoking helped
A mutation in the hemoglobin of a young woman in Germany was found to cause her mild anemia.
No safe level of smoking
People who consistently smoked an average of less than one cigarette per day over their lifetime had a 64 percent higher risk of earlier death than people who never smoked.
More Smoking News and Smoking Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.