Reduced Neutrophil Elastase Inhibitor Elafin and Elevated Transforming Growth Factor-β Are Linked to Inflammatory Response in Sputum of Cystic Fibrosis Patients with

Research Question: Pulmonary disease progression in patients with cystic fibrosis (CF) is characterised by inflammation and fibrosis and aggravated by (Pa). We investigated the impact of Pa specifically on: 1) protease/antiprotease balance; 2) inflammation; and 3) the link of both parameters to clinical parameters of CF patients.

Methods: Transforming growth factor-β (TGF-β), interleukin (IL)-1β, IL-8, neutrophil elastase (NE) and elastase inhibitor elafin were measured (ELISA assays), and gene expression of the NF-κB pathway was assessed (reverse transcriptase PCR) in the sputum of 60 CF patients with a minimum age of 5 years. Spirometry was assessed according to American Thoracic Society guidelines.

Results: Our results demonstrated the following: 1) NE was markedly increased in Pa-positive sputum, whereas elafin was significantly decreased; 2) increased IL-1β/IL-8 levels were associated with both Pa infection and reduced forced expiratory volume in 1 s, and sputum TGF-β was elevated in Pa-infected CF patients and linked to an impaired lung function; and 3) gene expression of NF-κB signalling components was increased in sputum of Pa-infected patients, and these findings were positively correlated with IL-8.

Conclusion: Our study links Pa infection to an imbalance of NE and NE inhibitor elafin and increased inflammatory mediators. Moreover, our data demonstrate an association between high TGF-β sputum levels and a progress in chronic lung inflammation and pulmonary fibrosis in CF. Controlling the excessive airway inflammation by inhibition of NE and TGF-β might be promising therapeutic strategies in future CF therapy and a possible complement to cystic fibrosis transmembrane conductance regulator (CFTR) modulators.