The relationship of systemic inflammation to prior hospitalization in adult patients with cystic fibrosis

Abstract

Background: In cystic fibrosis (CF) patients, it has been suggested that systemic inflammation may be an important risk factor for poor health outcomes. The relationship of plasma inflammatory biomarkers to lung function and hospitalization history remains largely unexplored.

Methods: This cross-sectional study included 58 consecutive, clinically stable adults from the CF Clinic at St. Paul's Hospital (Vancouver, Canada). Blood levels of interleukin (IL)-6, IL-1β, C-reactive protein (CRP), interleukin (IL)-6, IL-1β, granzyme B (GzmB), chemokine C-C motif ligand 18 (CCL18/PARC), surfactant protein D (SP-D), lipopolysaccharide (LPS)-binding protein, and soluble cluster of differentiation 14 (sCD14) were measured using enzyme-linked immunosorbent assays, and LPS levels were measured using a Limulus amebocyte lysate assay. Spirometry was also performed. Multivariable linear regression analysis was used to assess relationships of the blood biomarkers to lung function.

Results: Lung function impairment was independently associated with elevated plasma levels of CRP (P < 0.01), IL-6 (P = 0.04), IL-1β (P < 0.01), and LBP (P < 0.01). Increasing age (P < 0.01), reduced body mass index (P = 0.02), prior hospitalizations (P = 0.03), and presence of Pseudomonas aeruginosa in sputum cultures (P < 0.01) were also associated with reduced lung function. Elevated concentrations of LPS in plasma were associated with a previous history of hospitalization (P < 0.05). There was a trend towards an increase in plasma IL-6 (P = 0.07) and IL-1β (P = 0.06) levels in patients who were previously hospitalized.

Conclusions: IL-6 and IL-1β are promising systemic biomarkers for lung function impairment and history of hospitalization in adult patients with CF.

Figure 1

Plasma biomarker concentrations in cystic fibrosis subjects with above-median (n = 29) and below-median (n = 29) FEV_1% predicted values. (A-D) Geometric mean plasma levels of IL-6, IL-1β, CRP, and LBP were higher in subjects with below-median FEV_1% predicted values than in those with above-median FEV_1% predicted values. (E) The geometric mean plasma level of GzmB was lower in subjects with below-median FEV_1% predicted values than in those with above-median FEV_1% predicted values.

Figure 2

Plasma IL-6 was significantly correlated with plasma IL-1β in cystic fibrosis subjects (n = 58). β ± SE = 0.595 ± 0.105; IL-6 and IL-1β ln-transformed. R² = 0.37; P < 0.01.