Conclusions
These data suggest that NE may increase pro-inflammatory sphingolipid signaling, and the association is strengthened in female patients and patients with MRSA.
Methods
Fifteen patients with CF provided two spontaneously expectorated sputum samples, one collected during a hospitalization for an acute pulmonary exacerbation and one from an outpatient visit at a time of clinical stability. Sputum was processed, and the supernatant assessed for active neutrophil elastase (NE) using a chromogenic microplate assay and sphingolipid content using reverse phase high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Relevant demographic data including age, sex, CF genotype, FEV1 % predicted, and sputum bacteriology were assessed as possible modifying factors that could influence the correlation between NE and sputum sphingolipids. Data were analyzed for linear correlation, with statistical significance pre-defined as P < 0.05.
Results
There was a significant association between the concentration of active NE and ceramide, sphingomyelin, and monohexosylceramide moieties as well as sphingosine-1-phosphate. The presence of Methicillin-resistant Staphylococcus aureus (MRSA), FEV1 % predicted, and female gender further strengthened the association of NE and sphingolipids, but Pseudomonas aeruginosa had no effect on the association between NE and sphingolipids. Conclusions: These data suggest that NE may increase pro-inflammatory sphingolipid signaling, and the association is strengthened in female patients and patients with MRSA.