Expression and regulation of interferon-related development regulator-1 in cystic fibrosis neutrophils.

A genome-wide association study identified interferon-related development regulator-1 (IFRD1), a protein expressed by neutrophils, as a key modifier gene in cystic fibrosis (CF) lung disease. Here, we investigated the expression and regulation of IFRD1 in CF neutrophils. IFRD1 expression was quantified in peripheral blood and airway neutrophils from patients with CF, patients with non-CF lung disease, and healthy control subjects. The regulation of IFRD1 expression was analyzed using isolated neutrophils and ex vivo stimulation assays with CF airway fluids. IFRD1 single-nucleotide polymorphisms (SNPs) were analyzed in a CF cohort (n = 572) and correlated with longitudinal lung function and IFRD1 expression. Patients with CF expressed higher protein levels of IFRD1 in peripheral blood neutrophils compared with healthy or non-CF disease control subjects. Within patients with CF, IFRD1 protein expression levels in neutrophils were lower in airway fluids compared with peripheral blood. High IFRD1 expression was positively associated with the production of reactive oxygen species (ROS) in CF neutrophils. In vitro regulation studies showed that CF airway fluid and the CF-characteristic chemokines CXCL8 and CXCL2 down-regulated IFRD1 expression in neutrophils, an effect that was mediated through CXCR2. Genetic analyses showed that three IFRD1 SNPs were associated with longitudinal declines in lung function, and modulated IFRD1 expression. These studies demonstrate that IFRD1 expression is systemically up-regulated in human CF neutrophils, is linked to the production of ROS, and is modulated by chemokines in CF airway fluids, depending on the IFRD1 genotype. Understanding the regulation of IFRD1 may pave the way for novel therapeutic approaches to target neutrophilic inflammation in CF.

Pro-resolving lipid mediator Resolvin D1 serves as a marker of lung disease in cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) is an autosomal recessive genetic disorder that affects multiple organs, including the lungs, pancreas, liver and intestine. Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) locus lead to defective proteins and reduced Cl- secretion and Na+ hyperabsorption in the affected organs. In addition, patients suffering from CF display chronic inflammation that contributes to the pathogenesis of CF. Recent work suggests that CF patients have a reduced capacity to biosynthesize specialized pro-resolving lipid mediators (SPMs), which contributes to the development and duration of the unwanted inflammation. Alterations in the metabolism of arachidonic acid (AA) and docosahexaenoic acid (DHA) to specialized pro-resolving mediators (SPMs), like lipoxins (LXs), maresins (MaRs), protectins (PDs) and resolvins (Rvs), may play a major role on clinical impact of airway inflammation in CF. METHODS: In this study, our aims were to detect and quantitate Resolvin D1 (RvD1) in sputum and plasma from patients with CF and compare levels of RvD1 with biomarkers of inflammation and lung function. We studied 27 CF patients aged 6 to 55 years (median 16 years) in a prospective approach. RESULTS: DHA can be found in the plasma of our CF patients in the milligram range and is decreased in comparison to a healthy control group. The DHA-derived pro-resolving mediator Resolvin D1 (RvD1) was also present in the plasma (286.4 ± 50 pg/ mL, mean ± SEM) and sputum (30.0 ± 2.6 pg/ mL, mean ± SEM) samples from our patients with CF and showed a positive correlation with sputum inflammatory markers. The plasma concentrations of RvD1 were ten times higher than sputum concentrations. Interestingly, sputum RvD1/ IL-8 levels showed a positive correlation with FEV1 (rs = 0.3962, p< 0.05). CONCLUSIONS: SPMs, like RvD1, are well known to down-regulate inflammatory pathways. Our study shows that the bioactive lipid mediator RvD1, derived from DHA, was present in sputum and plasma of CF patients and may serve as a representative peripheral biomarker of the lung resolution program for CF patients.

Airway inflammation in mild cystic fibrosis.

BACKGROUND: Airway infection and inflammation play major roles in the progression of cystic fibrosis (CF) lung disease. In patients with mild disease, airway inflammation is a clinically relevant and often underdiagnosed feature. Lung function, sputum cell counts, and cytokine profiles in CF with mild disease might be different in patients with and without involvement of small airway disease (SAD). METHODS: Patients with mild CF (n=32) and 22 healthy controls were enrolled in this study. Patients with CF were assigned to two groups: (1) patients without SAD (n=19, median age 12.3years, MEF25>50% predicted), and (2) patients with SAD (n=13 median age, 13.2years, MEF25<50% predicted). Lung function parameters were measured, cells in induced sputum were counted, and cytokines/chemokines (IL-1ß, IL-6, IL-8, TNF-α) were analyzed by real-time quantitative PCR (qRT-PCR) and cytometric bead array (CBA). RESULTS: Patients with CF had significant elevated levels of pro-inflammatory genes in qRT-PCR and secreted gene products in CBA compared to controls. Patients with CF and SAD had significantly increased trapped air (RV/TLC) and pronounced airway inflammation compared to controls as indicated by elevated levels of sputum biomarkers like total cells, neutrophils, and IL6. CONCLUSIONS: Our study demonstrated that patients with CF with mild disease defined by lung function might be further endotyped according to their involvement of SAD. In patients with CF and SAD, airway neutrophilic inflammation is more pronounced and is in part distinct from that seen in patients without SAD.