A quantitative scoring method for analyzing lung mucin levels could significantly improve how physicians diagnose and track asthma, chronic bronchitis (CB) and COPD, according to University of North Carolina (UNC) School of Medicine researchers in Chapel Hill.
Their recent study, “A Quantitative Lung Mucin Score to Identify Chronic Bronchitis,” introduced the Mucin Quantitative Score (MUCQ) — a novel metric that blends both the total concentration and biochemical composition of airway mucins to better identify multiple chronic respiratory conditions. The study was published in the journal, NEJM Evidence.
Mehmet Kesimer, PhDUNC Health, UNC School of Medicine
The research was conducted within the large, multicenter SPIROMICS cohort and was designed to refine earlier research — total mucin concentration alone — which proved useful in identifying CB, the authors said. This new method analyzes sputum and other lung mucus samples to detect airway mucus abnormalities, assess disease risk and track disease progression in patients over time.
According to the UNC press release, the stickiness of mucins is what protects the respiratory system from pathogens, toxins and physical damage. An excess and/or increased concentration of mucins can restrict and block the airways and lead to chronic bronchitis, COPD or asthma, the study noted.
The MUCQ score incorporates the ratio of two key mucin proteins, MUC5AC and MUC5B, along with the overall mucin load to generate a more nuanced, unitless score. Participants in the SPIROMICS study were initially classified based on a traditional mucin threshold of 2306 µg/ml, then reclassified using the new MUCQ cutoff of 4.30.
Among 164 clinically diagnosed chronic bronchitis patients, the MUCQ score more accurately categorized individuals than the total mucin concentration measure alone, leading to the:
- Up‑classification of 18 current smokers into the chronic bronchitis category
- Down‑classification of five current smokers
- Adjusted correction of three never‑smoked control participants who had been inaccurately labeled based on total mucin concentration
The reclassification improvements were statistically significant and showed strong correlations with other established markers of airway obstruction and chronic airway disease, researchers noted.
The study’s authors indicated that the MUCQ score may offer physicians a more objective and precise way to diagnose chronic bronchitis, monitor disease progression (into asthma for example) and evaluate treatment response. They also noted that future trials will be needed to establish the role of MUCQ in routine patient management and its potential applicability to other muco‑obstructive lung conditions.
The research was funded by the National Institutes of Health and collaborating institutions.
