Pseudomonas-derived Ceramidase Induces Production of Inflammatory Mediators from Human Keratinocytes via Sphingosine-1-Phosphate

A Pseudomonas aeruginosa-derived neutral ceramidase (PaCDase) isolated from a patient with atopic dermatitis was shown to effectively degrade ceramide in the presence of Staphylococcus aureus-derived lipids or neutral detergents. To understand the effect of ceramide metabolites on the functions of differentiating keratinocytes, we have conducted genes expressions analysis from PaCDase-, sphingosine-1-phosphate (S1P)-treated or untreated three-dimensionally cultured human primary keratinocytes, which form a stratum corneum, in the presence of Triton X-100 using high resolution DNA microarray. To evaluate the effects of PaCDase and S1P on keratinocyte functions, we applied an epicutaneous 24-h patch test on the EPI-Model in keratinocyte serum-free medium (keratinocyte-SFM) (Invitrogen; Carlsbad, CA, USA) by the method of Spiekstra et al. [25] with some modification. The Triton X-100 treated samples were labeled using Cy5, and the PaCDase or S1P samples were labeled with Cy3.