Anti-pseudomonas antibodies contribute to lung disease in cystic fibrosis.

Abstract

Abstract Cystic fibrosis (CF) is an inherited lethal disease caused by mutations in CFTR. Approximately 60% of patients have homozygous F508del mutation, but their lung function is quite variable. Gene modifier studies identified I MHC II alleles are associated with the age of first Pseudomonas aeruginosa (PA) infection and lung function. Thus, we assessed serological responses to PA among CF subjects with poor lung function (FEV1<70%) versus good lung function (FEV1>90%). Immunoprecipitation-proteomics using outer membrane proteins (OMPs) from PA and human serum identified OprI as a potential important B cell antigen. We found increased anti-mucoid PA antibodies in CF and higher titers against OMPs and recombinant OprI in patients with poor lung function. Mice that were immunized with either recombinant OprI or inactivated whole PA subcutaneously developed high IgG titers in serum. Immunized mice that were challenged with mucoid PA had more weight loss and more severe lung pathology compared to unimmunized controls. There was minimal weight loss in PA immunized Rag2KO mice (impaired T and B cells), suggesting a role of adaptive immunity in the pathology. We observed more sensitive responses in FABP-hCFTR mice (CFTR knockout except GI tract) that OprI-immunized group exhibited the highest anti-OprI IgG titer and the most significant weight loss after challenge. These data suggest that one mechanism by which class II MHC is a modifier gene in CF is through antigen presentation and determining the types of anti-PA antibodies are generated in CF. Anti-PA antibodies may contribute to CF lung disease that we are conducting systems serology studies to understand which antibody functions are exacerbating disease.