No abstract

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 pH 4.7 using [choline-methyl-14C]sphingomyelin as a substrate were markedly increased by 27- and 7-fold, respectively. Radio-thin-layer 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 phosphorylcholine (PC), most of the SM hydrolysis detected in AD were attributable not to the SMase but to a hitherto undiscovered epidermal enzyme, SM acylase, which releases free fatty acid and sphingosyl-PC (Sph-PC) instead of ceramides. The potential of this acylase-like enzyme to generate Sph-PC through SM hydrolysis was corroborated by thin-layer chromatographic analysis of the reaction products obtained using porcine kidney acylase, followed by high-performance liquid chromatography-mass spectrometry. Furthermore, Sph-PC was also detected by high-performance liquid chromatography-mass spectrometry 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-layer chromatographic analysis. These findings 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.

Sphingolipids, a major constituent of intercellular lipids, are an important determinant for both water-holding and permeability barrier function in the stratum corneum. To assess the pathogenic role of sphingolipids in the stratum corneum of dry skin disorders such as xerosis and asteatotic eczema in leg skin, ceramides were quantified by thin layer chromatography after n-hexane/ethanol extraction of resin-stripped stratum corneum and evaluated as micrograms/mg stratum corneum. In healthy leg skin (n = 49), there was age-related decline in the total ceramide, whereas xerosis (n = 25) and asteatotic eczema (n = 16) suffering significantly reduced water-holding properties, exhibited no definite decrease, rather slight increase in ceramide quantity with the same composition of each individual ceramide as compared to healthy age-matched controls. These data indicate that the seemingly elevated level of ceramide is an artificial effect due to inflammatory processes which result from susceptibility to dryness. Analysis of sebum-derived lipids present in the stratum corneum revealed that there was a significant decline in free fatty acids in xerosis and asteatotic eczema as compared to age-matched healthy controls, and a similar decline in triglycerides in the above three groups when compared to younger controls. Although the observed decrease in the stratum corneum lipids may well explain the high incidence of winter dry skin in older people, the progression toward asteatotic eczema can not be accompanied solely by a decrease in ceramide quantity, suggesting that the evolution of xerotic skin is associated with other moisturizing factors and/or environmental stimuli.

A practical quality-of-life measure applicable to patients with skin diseases is necessary. Recently developed dermatological quality-of-life measures must be translated and adapted for use in cultures other than the ones in which they were created. In this study, we translated and adapted culturally into Japanese a skin-disease-specific, brief quality-of-life measure, Skindex-16, and studied its reliability and validity. Forward-and back-translations of Skindex-16 were carried out. Six doubtful items as well as the term "skin condition" required a second forward- and back-translation to reach satisfactory agreement with the original instrument. Cross-cultural adaptation and cross-sectional questionnaire studies were then performed to evaluate the reliability and validity of the instrument. One hundred patients and 30 healthy adults responded to the Japanese version. The internal-consistency reliability of the final Japanese version of Skindex-16 was high (range of Cronbach's alpha for each scale, symptoms, emotions, and functioning, was 0.83-0.92). The Japanese version showed construct and content validity. As hypothesized, scores for dermatological patients were higher than those for healthy persons (mean global scores 36 +/- 23 vs 1 +/- 2, p < 0.001) and scores for patients with inflammatory diseases were higher than those for patients with isolated skin lesions (mean global scores 48 +/- 21 vs 22 +/- 17, p < 0.001), indicating a poorer quality of life. Most patients' responses to an open-ended question about their skin disease were similar to those of the American responders and were addressed according to the items. In conclusion, we have developed a semantically equivalent translation of Skindex-16 into Japanese. It is a reliable and valid measure of the effects of skin disease on the quality of life in Japanese patients.

Epidermal basal cell injury with colloid body formation is a characteristic feature of lichen planus. Infiltrated cells are thought to be responsible for the epidermal injury. Ultrastructural findings of colloid bodies are typical of apoptosis. Granzymes in cytotoxic T lymphocytes are involved in apoptosis probably together with perforin. Based on this background, we analyzed the role of granzyme B in the mechanisms of epidermal injury in lichen planus. On electron microscopy, basal and suprabasal cells showed condensed chromatin and fragmented nuclei which are typical morphological features of apoptosis. Nuclei of colloid bodies were positively stained by the in situ nick end labeling technique indicating that colloid bodies are subsequently formed in the process of apoptosis. Immunohistochemical staining showed CD8-positive infiltrating cells to contain granzyme B. Cells undergoing exocytosis also contained granzyme B. By immunoelectron microscopy, granzyme B molecules were observed to be secreted from a lymphocyte to an apoptotic keratinocyte. These findings suggest that granzyme B-positive CD8 cells seem to induce apoptosis of keratinocytes in lichen planus.