Neutrophil Membrane Cholesterol Content is a Key Factor in Cystic Fibrosis Lung Disease

作者：White Michelle M; Geraghty Patrick; Hayes Elaine; Cox Stephen; Leitch William; Alfawaz Bader; Lavelle Gillian M; McElvaney Oliver J; Flannery Ryan; Keenan Joanne; Meleady Paula; Henry Michael; Clynes Martin; Gunaratnam Cedric; McElvaney Noel G; Reeves Emer P^*

来源：EBioMedicine, 2017, 23: 173-184.

DOI：10.1016/j.ebiom.2017.08.013

• Cystic fibrosis
• Neutrophils
• Cholesterol
• Lung transplant therapy
• Ivacaftor therapy

Background: Identification of mechanisms promoting neutrophil trafficking to the lungs of patients with cystic fibrosis (CF) is a challenge for next generation therapeutics. Cholesterol, a structural component of neutrophil plasma membranes influences cell adhesion, a key step in transmigration. The effect of chronic inflammation on neutrophil membrane cholesterol content in patients with CF (PWCF) remains unclear. To address this we examined neutrophils of PWCF to evaluate the cause and consequence of altered membrane cholesterol and identified the effects of lung transplantation and ion channel potentiator therapy on the cellular mechanisms responsible for perturbed membrane cholesterol and increased cell adhesion.
Methodology: PWCF homozygous for the Delta F508 mutation or heterozygous for the G551D mutation were recruited (n=48). Membrane protein expression was investigated by mass spectrometry. The effect of lung transplantation or ivacaftor therapy was assessed by ELISAs, and calcium fluorometric and mu-calpain assays.
Findings: Membranes of CF neutrophils contain less cholesterol, yet increased integrin CD11b expression, and respond to inflammatory induced endoplasmic reticulum (ER) stress by activating mu-calpain. In vivo and in vitro, increased mu-calpain activity resulted in proteolysis of the membrane cholesterol trafficking protein caveolin-1. The critical role of caveolin-1 for adequate membrane cholesterol content was confirmed in caveolin-1 knockout mice. Lung transplant therapy or treatment of PWCF with ivacaftor, reduced levels of circulating inflammatory mediators and actuated increased caveolin-1 and membrane cholesterol, with concurrent normalized neutrophil adhesion.
Interpretation: Results demonstrate an auxiliary benefit of lung transplant and potentiator therapy, evident by a reduction in circulating inflammation and controlled neutrophil adhesion.

• 出版日期2017-9