Analysis of Abnormal Expression of Sphingomyelin Acylase in Atopic Dermatitis. Resulting in Ceramide Deficiency

特应性皮炎中鞘磷脂酰化酶的异常表达分析。

基本信息

批准号：
07457192
负责人：
KAWASHIMA Makoto
金额：
$ 2.69万
依托单位：
TOKYO WOMEN'S MEDICAL COLLEGE
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Previously, we demonstrated that there is a marked reduction in the amount of ceramide in the stratum corneum of both lesional and nonlesional forearms in atopic dermatitis(AD), suggesting that an insufficiency of ceramides in the stratum corneum is an etiologic factor in atopic dry and barrier-disrupted skin. In this study, we investigated, as a possible mechanism involved in the ceramide deficiency, whether sphingomyelin (SM) metabolism is altered in AD as compared to normal controls. In stripped stratum corneum and biopsied whole epidermis of patients with AD.SM hydrolysis as measured at pH4.7 using *choline-methyl-^<14>C* sphingomyelin as a substrate were markedly increased by 27-and 7-fold, respectively.Radio-thin-layr chromatography of the reaction products revealed that, whereas the SM hydrolysis in age-matched normal controls were associated with sphingomyelinase (SMase) that degrades SM to yield ceramides and phosphorylcholin (PC), most of the SM hydrolysis detected in AD were … More attributable not to the SMase but to a hitherto undiscovered epidermal enzyme. SM acylase, which releases free fatty acidand sphingosyl-PC (Sph-PS) instead of ceramides. The potential of this acylaselike enzyme to generate Sph-PC through SM hydrolysis was corroborated by thin-layr chromatographic analysis of the reaction products obtained using porcine kidney acylase, followed by high-perfomance liquid chromatography-mass spectrometry. Furthermore, Sph-PC was also detected by high-performance liquid chromatography-massspectrometry after incubation of SM with atopic stratum corneum samples. On the other hand, the stratum corneum of patients with contact dermatitis or chronic eczema exhibited neither increased SM hydrolysis nor the generation of Sph-PC upon radio-thin-layr chromatographic analysis. These findins suggest that SM metabolism is altered in AD,resulting in a decrease in levels of ceramides, which could be an etiologic factor in the continuous generation of atopic dry and barrier disrupted skin observed in AD. Less

此前，我们证明特应性皮炎（AD）中病变和非病变前臂角质层中的神经酰胺含量显着减少，表明角质层中神经酰胺不足是特应性干性和特应性皮炎的病因之一。在这项研究中，我们研究了鞘磷脂 (SM) 是否与神经酰胺缺乏有关。与正常对照相比，在AD患者的剥离角质层和活组织检查的整个表皮中，在pH4.7下使用*胆碱-甲基-^ 14 C*鞘磷脂作为底物测量SM水解显着改变。分别增加了 27 倍和 7 倍。反应产物的放射薄层色谱显示，而年龄匹配的正常对照中的 SM 水解与鞘磷脂酶 (SMase) 降解 SM 产生神经酰胺和磷酰胆碱 (PC)，AD 中检测到的大多数 SM 水解不是由 SMase 引起的，而是由迄今为止尚未发现的表皮酶 SM 酰化酶引起的，该酶会释放游离脂肪酸和鞘氨醇。 PC (Sph-PS) 代替神经酰胺这种酰基酶样酶通过 SM 生成 Sph-PC 的潜力。通过对猪肾酰化酶获得的反应产物进行薄层色谱分析，然后进行高效液相色谱-质谱分析，证实了水解作用。此外，在孵育后，通过高效液相色谱-质谱分析也检测到了Sph-PC。 SM 与特应性角质层样本另一方面，接触性皮炎或慢性湿疹患者的角质层。根据放射薄层色谱分析，SM 水解和 Sph-PC 的生成均未增加。这些发现表明，AD 中 SM 代谢发生改变，导致神经酰胺水平下降，这可能是连续生成的一个病因因素。 AD 中观察到的特应性干燥和屏障破坏的皮肤较少。