Impact of storage conditions on metabolite profiles of sputum samples from persons with cystic fibrosis.

BACKGROUND: Although recent studies have begun to elucidate how airway microbial community structure relates to lung disease in cystic fibrosis (CF), microbial community activity and the host's response to changes in this activity are poorly understood. Metabolomic profiling provides a means to investigate microbial activity and human cell activity within diseased airways. However, variables in sample storage and shipping likely affect downstream analyses and standards for sample handling are lacking.
METHODS: We assessed the impact of sample storage conditions on liquid chromatography mass spectrometry analysis of CF sputum samples.
RESULTS: Significant changes in global metabolomic profiles occurred in samples stored at room temperature or at 4°C for longer than one day. Untargeted metabolomic profiles were stable in sputum samples stored at -20°C or -80°C for at least 28 days. Quorum sensing molecules and phenazines, both considered important to the in vivo activity of Pseudomonas during airway infection, were detected after sample storage at room temperature for five days.
CONCLUSIONS: Sputum samples can be stored at -20°C or -80°C for weeks with minimal effect on global metabolomic profiles. This observation provides guidance in designing metabolomic studies that have the potential to deepen our understanding of how airway microbial communities impact lung disease progression in CF.