Cigarette smoke is the leading cause of chronic obstructive pulmonary disease (COPD), and unfortunately, it can also prevent one of the most common symptom-relieving drugs from working properly. The latter is according to new research published in Clinical Science, which echoes prior studies that have shown COPD patients who take lung medication have a harder time treating flare-ups associated with smoking.

COPD is a collective term that refers to a group of lung diseases, including emphysema, chronic bronchitis, chronic obstructive airways disease and, in some cases, asthma, according to the Centers for Disease Control and Prevention. Breathing trouble, mainly due to obstructed airflow, chest infections, and persistent production of phlegm, marks these conditions.. Over time, the chronic inflammation associated with the disease — caused by inflammatory proteins such as tumor necrosis factor-alpha and interleukin-1 beta — leads to permanent changes in the lungs. The walls of the airways thicken and more mucus is produced, making it even more difficult to breathe.

Salbutamol is one of the most common drugs prescribed to COPD patients. It works by widening the airways to make it easier to breathe. The drug is effective for the one out of four Americans with COPD who have never smoked cigarettes, but less so for those who used to smoke. Researchers haven't quite figured out why the drug is more effective for some than others.

"By understanding the mechanisms responsible for reduced sensitivity to current bronchodilators, we can then design alternative, more efficacious agents to help treat people with COPD, especially during a viral exacerbation,” lead author Dr. Chantal Donovan, from Monash University, said in a statement.

For the study, Donovan and his team assessed the effects of salbutamol on lungs exposed to cigarette smoke and a version of the influenza A virus in mice. The data revealed lung tissue that has been exposed to cigarette smoke and/or the flu virus was less responsive to the drug than clean tissue.

Although the mechanisms involved in this reduced effectiveness are poorly understood, researchers said the findings demonstrate a need for new drugs to treat COPD patients with flare-ups caused by smoking or the flu.

"There is a clear need for new therapies that can overcome the limitations of current drugs used to treat COPD and associated flare-ups," said senior study author Dr. Ross Vlahos. "When combined with knowledge gained through clinical research, animal models utilizing cigarette smoke exposure are a valuable tool in the quest to identify new therapies for this life-changing condition."

Researchers said their study can be used to help identify new targets that can potentially help patients with COPD who do not respond to current therapy that is available.

Source: Donovan C, Seow H. Bourke J, Vlahos R. Influenza A Virus Infection and Cigarette Smoke Impair Bronchodilator Responsiveness To B-Adrenoceptor Agonists In Mouse Lungs. Clinical Science. 2016.