Sphingosine's role in epithelial host defense: A natural antimicrobial and novel therapeutic.

Sphingosine is a natural sphingolipid found in membranes of all eukaryotic cells. In addition to its functions in cell signaling, sphingosine has broad-spectrum antimicrobial properties. Sphingosine's role as an antimicrobial is important in tissues such as the skin and respiratory epithelium. Reduction in the normal sphingosine level is associated with problems related to infection susceptibility. Therefore, exogenous sphingosine may be an effective antimicrobial therapeutic. Inhaled nebulized sphingosine has been shown to be effective at both preventing and treating pneumonia in multiple mouse models. We now show that inhaled sphingosine has low toxicity to the respiratory system, strengthening its case as an excellent candidate for a novel inhaled antimicrobial drug.