Avidity of antibodies against Pseudomonas aeruginosa during respiratory infection and the humoral immune response to different pathogens during pulmonary exacerbation in cystic fibrosis

Abstract

Cystic fibrosis (CF) is a genetic disease resulting from dysfunction of the CFTR protein, essential for the transport of ions and water across the cell membrane, and the lung disease is the most prominent clinical manifestation. Dehydration of the respiratory secretions occurs resulting in increased viscosity, impairing of mucociliary transport, developing chronic low airways obstruction, with bacterial colonization followed by infections, particularly with Pseudomonas aeruginosa, the most relevant bacterium for CF patients.Initially, an intermittent pulmonary colonization by P. aeruginosa is observed, but the persistent isolation of P. aeruginosa in respiratory culture may subsequently occur; this stage is called chronic infection, which is characterized, in the clinical part, by the appearance of pulmonary exacerbations (PEX), and by the acquisition of the mucoid phenotype by P. aeruginosa in the microbiological respiratory culture, caused by the production of an exopolyssaccharide named alginate. This stage of infection is marked by an elevated IgG immune response, which is correlated with tissue damage and poor prognosis. Besides, serum of CF patients has a defective functional capacity, suggesting that the antipseudomonal antibodies in these patients might be of low avidity, which may result in defective antigen clearance and predisposition to immune complex disease.In this context, the aim of the present research project is to measure the avidity of antipseudomonal antibodies against a commercially available pooled antigen. (St-Ag:1-17) and alginate, and to measure the serum concentration of antibodies against P. aeruginosa, Staphylococcus aureus, Burkholderia cepacia complex, Achromobacter xylosoxidans, Aspergillus fumigatus and Stenotrophomonas maltophilia before and during the period of PEX.