Increased total plasma TGF-β1 levels and deregulated IgA-IgM axis in chronic obstructive pulmonary disease

Background: Chronic obstructive pulmonary disease (COPD) is characterised by obstruction of the small airways and includes "flare-ups", which are sudden and significant worsening of symptoms, sometimes caused by infections. Methods: Patients with COPD (n = 38) and acute bronchitis (AB, n=35) were grouped based on age and examined at two time points: during flare-ups/infections and at day 30. We measured various biomarkers, including total plasma TGF-<span style="color: rgb(32, 33, 34); font-family: sans-serif; font-size: 16px; background-color: rgb(248, 249, 250);">β</span>1 levels, total IgA, total IgM, and Pseudomonas aeruginosa-specific IgA levels. Results: Increased TGF-<span style="color: rgb(32, 33, 34); font-family: sans-serif; font-size: 16px; background-color: rgb(248, 249, 250);">β</span>1 levels were detected in COPD patients in comparison to acute bronchitis patients, with no significant change observed at day 30. Paired analysis revealed a significant decrease in total plasma IgA levels in COPD patients on day 30. No significant difference in specific P aeruginosa IgA levels was observed between the two patient groups. Interestingly, a correlation between total IgM and IgA levels was absent in COPD patients, unlike in those with acute bronchitis. While a positive correlation existed between age and IgA level in patients with acute bronchitis, this correlation was negative in patients with COPD. A significant correlation was observed between total IgM and P aeruginosa-specific IgA in acute bronchitis patients. On the other hand, COPD patients showed no correlation between total IgA or IgM and P aeruginosa-specific IgA levels at different time points. Conclusions: We report on the deregulated IgA-IgM axis in COPD and call for thorough, larger-scale studies of the humoral immune system in this pathology.