Shigeo Serizawa

Stratum corneum lipid abnormalities in atopic dermatitis

SummaryPatients with atopic dermatitis (AD) often present with a dry skin. To clarify the relationship between dry skin and lipid abnormalities within stratum corneum, stratum corneum lipids were collected from six AD patients aged 15 to 25 years and from sex- and age-matched controls. All major stratum corneum lipid classes were separated and quantitated by high-performance thin-layer chromatography/photodensitometry. Six ceramide fractions were also isolated and quantitated by thin-layer chromatography/photodensitometry. Esterified fatty acids of both ceramide 1 (acylceramides) and wax esters were analysed by capillary gas chromatography. The relative amounts of all the stratum corneum lipid classes including squalene, cholesterol esters, wax esters, triglycerides, free fatty acids, cholesterol, ceramides, cholesterol sulphate and phospholipids did not differ statistically between AD patients and controls. However, a significant decrease in proportion of ceramide 1, which is believed to be a carrier of linoleate responsible for a water-barrier function, and increased levels of esterified C18∶1 fatty acids (oleate) of ceramide 1 were observed in AD patients. On the other hand, the fatty acid compositions as well as the proportions of C16∶1 straight-chain component in sebum wax esters of AD patients were very similar to those of controls. These results suggest that a significantly reduced amount and/or structural alterations of ceramide 1 deriving from epidermal keratinocytes may be responsible for the impaired water-barrier function of the skin in AD.

Fatty acid composition of sebum wax esters and urinary androgen level in normal human individuals.

To investigate the effects of androgens on the fatty acid compositions of sebum wax esters, we examined sebum and urinary samples from 36 healthy individuals, aged from 3 to 59 years. The percentages of C16:1 straight chain components in wax esters were correlated positively with the urinary testosterone levels in both sexes, and with the urinary levels of etiocholanolone and total 17-ketosteroids (17-KS) in females. These data suggest that more active sebaceous glands in lipid production excrete sebum with a higher proportion of C16:1 straight chain fatty acid, which is considered to be purely endogenous. It appears, therefore, that the proportion of C16:1 straight chain fatty acid in sebum wax esters may indicate the sebaceous gland activity in both sexes. In comparison of the amounts of various straight and terminally branched fatty acids in sebum with urinary androgen levels, the straight even fatty acids tended to change in a positive correlation with testosterone levels, in contrast to the changes of the iso even fatty acids in both sexes and to those of the iso odd fatty acids in males. The straight odd fatty acids showed a similar change to that of the straight even fatty acids in males, while in females, there was no significant correlation between the amounts of the fatty acids and testosterone levels. Anteiso fatty acids showed no notable change correlated with testosterone levels. This result suggests that the synthesis of iso or anteiso fatty acids may be controlled by complex factors and that there may be a unique source of anteiso fatty acids in human sebaceous glands.

Cholesterol sulphate levels in the hair and nails of patients with recessive X-linked ichthyosis

Cholesterol sulphate (CS) has been suggested as an intercellular glue fur corneocyte‐corneocyte cohesion from studies on patients with recessive X‐linked ichthyosis (RXLI). Pathological stratum corneum of RXLI patients was found to show a significant elevation of CS. In the present study hair and nails, unaffected keratinzed tissues in RXLI patients, were examined for CS levels. The results demonstrated significantly elevated CS levels in both tissues in RXLI patients (P < 0.001). In particular the mean CS level in the hair of RXLI patients was five times greater than normal. The present study suggests that hair is a useful material for the diagnosis of RXLI.

Bound lipids liberated by alkaline hydrolysis after exhaustive extraction of pulverized clavus

In the present study, covalently bound lipids were found in clavus material and their lipid classes were determined by high-performance thin-layer chromatography (HPTLC). Clavus material, pulverized completely in a Mikro-Dismembrator II, was exhaustively extracted three times with chloroform/methanol (2∶1, 1∶1 and 1∶2 v/v) at 80‡C for l h each time and this sequence of extractions was repeated to obtain the unbound lipid-free residue which was saponified and then extracted with chloroform. The extract proved to comprise several bands of lipids covalently bound through an ester-like linkage. These were identified as free fatty acids, cholesterol, ceramides and glucocerebrosides by HPTLC. However, Ω-hydroxy fatty acids were not detected in the lipids. To analyse the fatty acids amide-linked to the bound ceramides, the latter were isolated by preparative HPTLC and subjected to mild acid hydrolysis. Since the bound ceramides constituted neither Ω-hydroxy fatty acids nor α-hydroxy fatty acids, they were not identified as hydroxyl-acylsphingosines.

Simplified determination of serum cholesterol sulfate by gas-liquid chromatography combined with cyclohexylsilane-bonded phase column purification

SummaryA new gas-liquid chromatographic (GLC) determination of cholesterol sulfate (CS) and dehydroepiandrosterone sulfate (DHEAS) for a biochemical diagnosis of recessive X-linked ichthyosis (RXLI) is described. Although the GLC method for determination of CS is known to be more sensitive than the thin layer chromatographic (TLC) method, the former method has not been widely employed because of its complicated pre-purification steps. The present method allows us to measure the serum levels of CS and DHEAS without tedious purification steps such as multiple conventional column chromatography and preparative thin layer chromatography. Sulfated steroids are rapidly purified with a commercially available mini disposable cyclohexylsilane-bonded phase (CH) column, CH BOND ELUT, and the purified steroids after desulfation are converted to water-resistant tert-butyldimethylsilyl ether derivatives for the GLC analysis on dual 2 m glass columns packed with 2% XE-60 on Chromosorb W.By the present method, serum CS concentrations in RXLI patients were shown to be about 10 times higher than those in patients with ichthyosis vulgaris, carriers of RXLI, and healthy subjects. This method is more suitable not only for a biochemical diagnosis of RXLI but also for studies on the metabolism of sulfated steroids than the previous time-consuming GLC methods.

A Case of Recessive X-Linked Ichthyosis : Scale-Specific Abnormalities of Lipid Composition May Explain the Pathogenesis of the Skin Manifestation

We analyzed the lipid content of the scales, red blood cells, and plasma from a recessive X‐linked icthyosis patient. The patients scales accumulated cholesterol sulfate, had decreased levels of free sterols, sterol esters and sphingolipids, and lacked phospholipids. Although the accumulation of cholesterol sulfate was found in the patients red blood cells and plasma as well as in the scales, other lipid composition abnormalities were specific for scales. Such scale‐specific abnormal lipid composition may explain the pathogenesis of generalized hyperkeratosis and abnormal scaling of the disease.