Sputum Protein Biomarkers in Airway Diseases: A Pilot Study

Area of Science:

• Respiratory Medicine
• Proteomics
• Biomarker Discovery

Background:

• Chronic mucous hypersecretion (CMH), often seen in chronic bronchitis, asthma, and COPD, has significant adverse clinical effects.
• The sputum fluid phase contains candidate proteins, including mucins, with therapeutic potential, but these remain underexplored.
• Understanding sputum protein profiles is crucial for managing airway diseases.

Purpose of the Study:

• To investigate the protein profile in the sputum fluid phase of patients with various airway diseases.
• To identify potential protein biomarkers for differentiating clinical phenotypes and predicting exacerbation frequency.

Main Methods:

• Sputum samples from 31 patients with airway diseases were analyzed using LC-MS/MS.
• Quantitative proteomics was performed using sequential window acquisition of all theoretical fragments ion spectra (SWATH) on 15 samples.
• Hierarchical clustering and functional grouping were employed for protein analysis.

Main Results:

• A total of 185 proteins were quantified, with 21 proteins distinguishing between clinical phenotypes via hierarchical clustering.
• Functional protein clusters identified inflammation, oxidative stress, mucin, and cytoskeletal/calcium-related groups.
• Eight specific proteins and total sputum protein concentration were significantly altered in frequent exacerbators.

Conclusions:

• Sputum proteins effectively differentiate clinical phenotypes in airway diseases.
• Total protein concentration and eight identified proteins are potential biomarkers for frequent exacerbators.
• Further research is needed to evaluate the clinical and therapeutic implications of these protein groups.