The role of neutrophils in cystic fibrosis

Abstract

Neutrophils are known to dominate the pulmonary inflammatory process observed in cystic fibrosis (CF). An enduring paradox is how these large numbers of neutrophils fail to eradicate colonizing bacteria. Major advances in our understanding of neutrophil dysfunction in CF and its effect on the innate immune system are leading to advances in our understanding of the pathophysiology and leading directly to new therapies. New mechanisms of neutrophil dysfunction have been described in CF including disabled cystic fibrosis transmembrane conductance regulator recruitment to phagosomes and novel mechanisms of protease-induced neutrophil dysfunction. Neutrophil elastase has been shown to be present in the airway very early in life in CF patients, and appears a biomarker of disease progression, predicting lung function decline and bronchiectasis. Elastase has also been shown to induce a pro-inflammatory state of senescence in bronchial epithelial cells in vitro and potentially in vivo. Inhibitors of neutrophil elastase are now entering clinical trials with promising results. New avenues of CF therapeutics are being explored including novel macrolides, CXCR2 antagonists and exogenous opsonins. This article reviews the past 12 months of research that contributes to our understanding of the role of neutrophils and immune dysfunction in CF.