Iron-binding proteins in sputum of chronic bronchitis patients with Haemophilus influenzae infections

Abstract

Airway inflammation during infection is associated with increased transudation of serum proteins and increased production of protein by the airway epithelium. We therefore, assessed whether Haemophilus influenzae infections in patients with chronic bronchitis are associated with increased levels of transferrin and lactoferrin in the sputum compared to uninfected patients.Sputum sol phase and serum samples from 14 infected and 13 uninfected patients with chronic bronchitis and from 12 bronchial asthma patients were included in the study.The median Q-values (the concentration in sputum sol phase/the concentration in serum) × 10 3 of transferrin appeared increased in chronic bronchitis patients with an H. influenzae infection (26.0, n=13) compared to uninfected controls (9.5, n=11) and bronchial asthma patients (4.5, n=6). The ratio of the Q(transferrin)/Q(albumin) was >1 in infected chronic bronchitis patients, indicating local production of transferrin. Growth of H. influenzae was stimulated more in sputum from infected and uninfected patients with chronic bronchitis than in sputum from patients with bronchial asthma. The concentrations of lactoferrin were not significantly different in infected (n=14) and uninfected (n=13) chronic bronchitis patients and bronchial asthma patients (n=12) (median 137.4, 84.6, 87.1 mg·L -1 , respectively).We conclude that in patients with chronic bronchitis with Haemophilus influenzae infections, the levels of transferrin are increased and the levels of lactoferrin are not associated with infections.

Effects of Bacterial Infection on Airway Antimicrobial Peptides and Proteins in COPD

“…Previous authors have reported a lack of increase in respiratory lactoferrin levels with NTHI infection in COPD. 43 A clear explanation for this observation is lacking and needs further investigation. P Յ .001) (e- Fig 7).…”

Role of iron in the pathogenesis of respiratory disease

“…influenzae can also source iron through the uptake of host proteins such as LF, ferritin and haemoglobin (Pidcock et al, 1988;Vogel et al, 1997a). Significantly, studies have shown that TF levels are increased in the sputum of patients with chronic bronchitis associated with H. influenzae infections (Vogel et al, 1997b). However, whether the increased TF levels are the consequence of chronic bronchitis or are the cause of chronic infection and, therefore, the driver of disease, remains to be elucidated.…”

Immunization with Recombinant Transferrin Binding Protein B Enhances Clearance of Nontypeable Haemophilus influenzae from the Rat Lung

“…Transferrin selectively accumulates in the lungs and is found primarily in the alveoli (3,29), where it appears to act as an important antioxidant in the protection of cellular membranes against iron-dependent lipid peroxidation (23). Notably, NTHI stimulates the production of transferrin, which is increased in the sputum sol phase of patients with chronic bronchitis who are infected with this bacterium (29). Thus, the ability of NTHI to gain access to the human iron pool by sequestering iron from transferrin may provide an important mechanism that enhances bacterial survival within the respiratory tract.…”