Neonates with cystic fibrosis have a reduced nasal liquid pH; a small pilot study

Abstract

Background: Disrupted HCO3(-) transport and reduced airway surface liquid (ASL) pH in cystic fibrosis (CF) may initiate airway disease. We hypothesized that ASL pH is reduced in neonates with CF.

Methods: In neonates with and without CF, we measured pH of nasal ASL. We also measured nasal pH in older children and adults.

Results: In neonates with CF, nasal ASL (pH5.2 ± 0.3) was more acidic than in non-CF neonates (pH6.4 ± 0.2). In contrast, nasal pH of CF children and adults was similar to values measured in people without CF.

Conclusions: At an age when infection, inflammation and airway wall remodeling are minimal, neonates with CF had an acidic nasal ASL compared to babies without CF. The CF:non-CF pH difference disappeared in older individuals, perhaps because secondary manifestations of disease increase ASL pH. These results aid understanding of CF pathogenesis and suggest opportunities for therapeutic intervention and monitoring of disease.

Keywords: Airway surface liquid (ASL); Cystic fibrosis; Neonatal screen; Neonates; pH.

Fig. 1. Nasal ASL pH

A. pH of nasal ASL in healthy volunteers (n=5) before and after aerosol administration of a 5% NaHCCb or 5% NaCl solutions. Data are mean ±SEM; some error bars are hidden by symbols. B. Nasal pH in non-CF (white, n=23) and CF (dark gray, n=7) neonates, children (n=l 1 non-CF and n=14 CF), and adults (n=10 non-CF and n=10 CF). Data points are values for individuals, bars are means ±SEM. * p <0.01 (Student’s t test). C. Nasal pH in neonates with no CFTR mutations (n=4), neonates heterozygous for a CFTR mutation (n=19) and neonates with CF (n=7). * p <0.01 (one-way ANOVA, Bonferroni’s multiple comparisons test).