Activated complement in the sputum from patients with cystic fibrosis

Area of Science:

• Immunology
• Pulmonology
• Medical Microbiology

Background:

• Cystic fibrosis (CF) is a genetic disorder affecting the lungs, often leading to chronic infections.
• Pseudomonas aeruginosa (P. aeruginosa) is a common pathogen in CF patients, contributing to lung damage.
• The role of complement system activation in CF lung pathogenesis is not fully understood.

Purpose of the Study:

• To investigate complement factor levels in the sputum of CF patients with and without chronic P. aeruginosa infection.
• To determine the association between complement activation, inflammation, and P. aeruginosa infection in CF.

Main Methods:

• Examined plasma and sputum sol phase for complement factors (albumin, C1q, C3/C3c, C4, C5) using electroimmunoassays.
• Analyzed sputum sol phase for factor B via rocket immunoelectrophoresis.
• Compared complement levels between CF patients with (CF + P) and without (CF-P) P. aeruginosa infection.

Main Results:

• C3c was significantly more frequent in the sputum of CF + P patients compared to CF-P patients (p < 0.01).
• Factor B was detected in sputum, but no significant difference was found between the groups.
• No evidence of local pulmonary production of complement factors was observed.
• Complement activation strongly correlated with inflammation markers (p < 0.01).

Conclusions:

• Complement activation, particularly C3c, is associated with P. aeruginosa infection and inflammation in CF patients' lungs.
• Findings support the hypothesis that chronic P. aeruginosa lung infection in CF is an immune complex disease.
• Complement-mediated inflammation plays a crucial role in the pathogenesis of pulmonary tissue damage in CF.