Innate Immune Response in COPD

The airways of COPD patients are often colonized with bacteria leading to increased airway inflammation. This study sought to determine whether systemic cytokine responses to microbial pathogen-associated molecular patterns (PAMPs) are increased among subjects with severe COPD.

In an observational cross-sectional study of COPD subjects, PAMP-induced cytokine responses were measured in whole blood ex vivo. We used PAMPs derived from microbial products recognized by TLR 1, 2, 4, 5, 6, 7, and 8. Patterns of cytokine response to PAMPs were assessed using hierarchical clustering. One-sided t-tests were used to compare PAMP-induced cytokine levels in blood from patients with and without severe COPD, and for subjects with and without chronic bronchitis.

Inclusion criteria

• post-bronchodilator FEV1/FVC <0.7
• FEV1 < 80%
• > 10 pack-years tobacco smoking
• no respiratory illnesses or prednisone or antibiotics in the last 4 weeks

Exclusion criteria

• Primary diagnosis of asthma
• > 15% change in FEV1
• Chronic inflammatory or infectious disease
• Cancer
• Autoimmune disease
• Chronic renal failure with a creatinine > 1.5
• Chronic liver disease
• Chronic antibiotic use

Note: Due to difficulty recruiting patients after 6 participants were enrolled, the exclusion criteria were modified to allow patients with > 15% change in FEV1. The exclusion criteria were also changed to allow chronic renal failure not requiring dialysis, and non-metastatic cancer provided there was no diagnosis of lung cancer.