Effetct of Pseudomonas aeruginosa-derived neutral ceramidase on immunological responses of three-dimensionally cultured human primary keratinocytes

从特应性皮炎患者中分离的铜绿假单胞菌衍生的中性神经酰胺酶（PaCDase）显示出有效降解神经酰胺。神经酰胺代谢产物鞘氨醇-1-磷酸（S1 P）刺激三维培养的人原代角质形成细胞（3D角质形成细胞）产生炎症介质，如TNF和IL-8。PaCDase诱导TNF和IL-8的产生，并且这种产生依赖于神经酰胺酶的酶活性。S1 P增强TNF和IL-8的基因表达，并且这种增强被鞘氨醇激酶抑制剂和S1 P受体拮抗剂抑制。TNF结合抗体英夫利西单抗抑制PaCD酶诱导的IL-8 mRNA上调，但不抑制TNF mRNA上调。这些发现表明，3D角质形成细胞从鞘氨醇产生S1 P，鞘氨醇通过PaCDase水解神经酰胺产生，然后S1 P诱导这些细胞产生TNF，导致IL-8的产生。

A Pseudomonas aeruginosa-derived neutral ceramidase (PaCDase) isolated from a patient with atopic dermatitis was shown to effectively degrade ceramide. The ceramide metabolite sphingosine-1-phosphate (S1P) stimulated the production of inflammatory mediators such as TNF and IL-8 from three-dimensionally cultured human primary keratinocytes (3D keratinocytes). PaCDase induced the production of TNF and IL-8, and this production was dependent on ceramidase enzymatic activity. S1P enhanced the gene expression of TNF and IL-8, and this enhancement was inhibited by a sphingosine kinase inhibitor and an S1P receptor antagonist. The TNF-binding antibody infliximab suppressed the PaCDase-induced upregulation of IL-8 mRNA but not of TNF mRNA. These findings suggest that, 3D keratinocytes produce S1P from sphingosine, which is produced through the hydrolysis of ceramide by PaCDase, and then S1P induced TNF production from these cells, resulted in production of IL-8.