Pilot 16 – Pseudomonas-specific immune responses in CF patients

P.I.: Marion Pepper, PhD
Associate Professor, Immunology

A major cause of morbidity and mortality in patients with cystic fibrosis (CF) is chronic lung infection with Pseudomonas aeruginosa, a ubiquitous gram-negative bacillus. P. aeruginosa infection starts with a non-mucoid planktonic variant that can further develop into a chronic biofilm growing form that is resistant to both immune-mediated and antibiotic killing and therefore difficult to eradicate. Biofilm formation is also associated with a tissue damaging hyper-inflammatory response, characterized by the activation of pathological Th17 cells in both lung and draining lymph nodes and subsequent neutrophilia. Therefore, understanding how to both disrupt P. aeruginosa biofilms and optimize immune-mediated killing of bacteria is a primary goal for the generation of novel therapeutic interventions. Antibodies produced by B cells of the humoral immune response have been shown to have the capacity to both disrupt P. aeruginosa biofilms and kill the bacteria through opsonization. Little is known, however, about the differentiation, function or maintenance of P. aeruginosa-specific B cells in either healthy or CF individuals or whether these functions happen in vivo. To address this lack of knowledge, we have produced B cell tetramers containing either polysaccharides or proteins from P. aeruginosa. Using these tetramers and a novel magnetic bead-based cell enrichment method of our design, we will analyze the phenotype and function of P. aeruginosa-specific B cells in PBMCS in collaboration with Drs. Bonnie Ramsey and Pradeep Singh at the University of Washington Cystic Fibrosis and Research Translation center (CFRTC). In collaboration with the CFRTC Host Response core, we will look for the localization of various immune populations in tissues sections from CF or healthy lungs to determine if tissue resident memory lymphocytes are preferentially maintained in either cohort. The central hypothesis of this application is that chronic infection and inflammation alters the P. aeruginosa B cell response, allowing for repeat recolonization. This innovative pilot approach will provide preliminary data and reveal novel hypotheses that can be addressed through these unique collaborations in future projects.