COPD: Spitting Out An Evaluation

28. December 2017

Chronic obstructive pulmonary disease (COPD) often develops unnoticed. Early treatment here significantly improves quality of life. Doctors from the USA have now found a biomarker for COPD in sputum. This should facilitate early diagnosis.

An otherwise healthy patient presents at his family doctor with persistent cough and sputum. When taking a medical history, the doctor quickly identifies one risk factor: his patient is a smoker. Although during the physical examination auscultation of the lungs finds nothing unusual, chronic bronchitis could still be present.

If breathing noises such as whistling or humming are discernable, a moderate stage of chronic obstructive pulmonary disease (COPD) has already normally been reached. If this whistling and humming is not heard, doctors tend to not consider the presence of COPD. An early diagnosis would be helpful here. COPD cannot be healed; timely treatment is nevertheless important because the symptoms can in this way be alleviated and the quality of life can be significantly improved.

COPD is associated with the progressive, irreversible narrowing of the airways. According to the WHO, COPD ranks fourth in the world in terms of diseases with the most deaths.

The diagnostic tool of choice

The first system which the doctor usually reaches for when diagnosing COPD is spirometry. In this lung function test, lung volume is measured by maximum exhalation and inhalation as well as by forced breathing. A study from the year 2015 however shows that this test can also arrive at misdiagnoses. The team led by Elizabeth A. Regan from Denver examined 8,872 active and former smokers who smoked at least one pack of cigarettes a day. In half of the subjects, the lungs were classified as healthy based on spirometric examination. In CT scans however, 42 percent of the patients classified as healthy were found to have obstructive airway changes – an onset of COPD. By the time limitations are able to be detected in the pulmonary function test, a large part of the lung tissue has usually already been destroyed. Timely diagnosis is important in order to slow or prevent the progression of early-stage COPD.

Severity gets new classification system

The Global Initative for Chronic Obstructive Lung Disease (GOLD) revised the guidelines for the classification of severity of COPD in 2017. Previously the decisive criteria had been reductions in FVC (FEV1) and forced vital capacity (FVC) as measured via spirometry. Taking into account the severity of the symptoms and exacerbations, four severity-defined GOLD stages resulted. As the study by Elizabeth A. Regan however shows, there is only a weak correlation between FEV1, symptoms and impairment of health status. Therefore, in the revised guidelines the spirometric parameters are now only considered separately from symptoms and exacerbations. This thereby gives the latter a greater weighting in the classification of severity. Individual diagnosis and treatment would therefore be able to be refined and improved.

Sputum as a biomarker

Although sputum is considered a major symptom of COPD, it has not been used to assess severity. Physicians from the University of North Carolina at Chapel Hill, USA, may now have found a suitable biomarker for COPD in sputum. The researchers discovered that the bronchial mucus of patients with COPD exhibited a higher concentration of mucins. Mucins are structural components in the bronchial mucus and consist of proteins and carbohydrate chains of various lengths. This mucus covers the epithelium of the respiratory tract and captures pathogens and pollutants and ensures their removal by moviing them along towards the throat.

The optimal composition of bronchial mucus is therein instrumental in the success of this self-cleaning mechanism – the mucociliary clearance – which involves the lungs. In healthy people, mucus consists of 98 percent water and about 2 percent solids, mainly mucins. In patients with COPD this balance is disturbed; their bronchial mucus has twice the concentration of mucins. As a result, the mucus sticks to the bronchial epithelium and lumps are formed, which are ejected during coughing.

In the study, the researchers examined the sputum of 917 subjects by way of mass spectrometry. This group was made up of non-smokers, being the control, and COPD patients at the various GOLD stages. Among the participants were also long-term smokers with severe COPD. The mucin concentration of patients with severe COPD was on average 3166 μg/ml and 1515 μg/ml in non-smokers – this value being normal. The average concentration increased in subjects with two or more exacerbations to 4194 μg/ml. An increase in mucin concentration was therefore associated with a worsening of the disease.

Hope for new therapies

“As a next step, we want to develop a practical test that will help doctors diagnose chronic bronchitis or COPD”, lead author Prof. Mehmet Kesimer says. “This is an important step in COPD research”, James P. Kiley, director of the National Heart, Lung and Blood Institute (NHLBI), says in a press release: “If we understand how mucus behaves at the various grades of disease severity, this helps us develop new therapies”. According to the study authors, these therapies might be aimed at restoring mucus balance in the bronchi and thereby may alleviate symptoms.

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1 comment:

Megan Shafer
Megan Shafer

This or should i say these individual diseases, all under the guise of COPD. Need to be brought to the forefront , a 17 hundreds and before disease, and this is where they are….shame on the medical profession, the pharmaceutical industry, researchers. They have not worked on lung diseases at all…it’s the same repeated research. This needs cured it’s 2018…it’s a human travesty., and lack of trying if it is not. Newer diseases have cured, Lets make 2018 the year the cure a millueums old disease. It’s way passed time….if you can breath, you can do anything.

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