Inhibition of Microbial Adherence by Sphinganine

Sphingosines (precursors and degeneration products of complex sphingolipids) are mediators in membrane second-messenger cascades and in a wide variety of functions in eukaryotic cells. Sphingosines are also lethal for gram-positive microorganisms. In addition to its direct effect, sphinganine is here reported to affect the adherence of Streptococcus mitis to buccal epithelial cells and of Staphylococcus aureus to nasal mucosal cells after incubation for 90 min at 37 degrees C. When the bacteria were pretreated with 8.1, 16.2, 32.5, or (for Strep. mitis) 65 microM sphinganine for 60 min at 37 degrees C, adherence counts were reduced for Staph. aureus by 27, 37, and 60% and for Strep. mitis by 19, 44, 54, and 73%, respectively (p < 0.001). In contrast, pretreatment of buccal cells with 81.2 microM lipid increased adherence by 14% (p < 0.01), but no change occurred at either 16.2 or 325 microM lipid. These results further demonstrate the double-edged ability of sphingosines to regulate cellular activities and their potential as multifunctional therapeutic agents for infectious diseases.