Effect of Haemophilus influenzae infection on lung CD8+ T cells in COPD

Veterans Health Administration, Decatur PA

Investigators

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Abstract

DESCRIPTION (provided by applicant): Chronic obstructive pulmonary disease (COPD) is the 3rd leading cause of death in the U.S., yet there are no current therapeutic treatments to halt the progression of this disease. COPD is characterized by airflow obstruction, variable degrees of airway remodeling and alveolar destruction, and an influx of lung inflammatory cells, including neutrophils, macrophages, and CD8+ T cells. The inverse correlation between numbers of airway CD8+ T cells and lung function, as determined by FEV1, implicates CD8+ T cells in COPD pathogenesis. CD8+ T cells can release inflammatory cytokines and mediators that could contribute to lung destruction. These effectors functions are augmented when lung CD8+ T cells are co-stimulated with synthetic bacterial ligands recognized by toll-like receptors (TLRs), in particular TLR2/1. TLR2/1 is known to recognize the outer membrane protein of nontypeable Haemophilus influenzae (NTHI), one of the predominant bacterial pathogens associated with airway infection in COPD, both in stable disease and as an important infectious trigger of exacerbations. The goal of this study is to determine whether lung CD8+ T cells will respond to NTHI co-stimulation by up-regulating their effector functions, such as secreting inflammatory cytokines, killing autologous lung cells, and recruiting additional CD8+ T cells. To carry out this objective, lung tissue from consented subjects undergoing clinically-indicated surgical resections will be used. Tissue will be obtained from both subjects with and without COPD. Isolated lung CD8+ T cells will be co-cultured with antigen- presenting cells and NTHI to determine what effect NTHI co-stimulation has on the production of effector molecules, which will be measured by flow cytometry. This will be correlated with measures of lung function. The co-culture assay will also be used to determine whether NTHI co-stimulation induces the lung CD8+ T cells to kill autologous lung cells. By isolating CD8+ T cells directly from human lung tissue and using them in vitro to study CD8 and NTHI interactions, we may gain unique insights into how COPD pathogenesis is initiated and progresses.