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

Sulfate-based lipids: Analysis of healthy human fluids and cell extracts

Sulfate-based lipids (SL) have been proposed as players in inflammation, immunity and infection. In spite of the many biochemical processes linked to SL, analysis on this class of lipids has only focused on specific SL sub-classes in individual fluids or cells leaving a range of additional SL in other biological samples unaccounted for. This study describes the mass spectrometry screening of SL in lipid extracts of human fluids (saliva, plasma, urine, seminal fluid) and primary human cells (RBC, neutrophils, fibroblasts and skin epidermal) using targeted precursor ion scanning (PIS) approach. The PIS 97 mass spectra reveal a wide diversity of SL including steroid sulfates, sulfoglycolipids and other unidentified SL, as well as metabolites such as taurines, sulfated polyphenols and hypurate conjugates. Semi-quantification of SL revealed that plasma exhibited the highest content of SL whereas seminal fluid and epithelial cells contained the highest sulphur to phosphorous (S/P) ratio. The complexity of biofluids and cells sulfateome presented in this study highlight the importance of expanding the panel of synthetic sulfate-based lipid standards. Also, the heterogenous distribution of SL provides evidence for the interplay of sulfotransferases/sulfatases, opening new avenues for biomarker discovery in oral health, cardiovascular, fertility and dermatology research areas.

Skin Barrier Function Is Not Impaired and Kallikrein 7 Gene Polymorphism Is Frequently Observed in Korean X-linked Ichthyosis Patients Diagnosed by Fluorescence in Situ Hybridization and Array Comparative Genomic Hybridization

X-linked ichthyosis (XLI) is a recessively inherited ichthyosis. Skin barrier function of XLI patients reported in Western countries presented minimally abnormal or normal. Here, we evaluated the skin barrier properties and a skin barrier-related gene mutation in 16 Korean XLI patients who were diagnosed by fluorescence in situ hybridization and array comparative genomic hybridization analysis. Skin barrier properties were measured, cytokine expression levels in the stratum corneum (SC) were evaluated with the tape stripped specimen from skin surface, and a genetic test was done on blood. XLI patients showed significantly lower SC hydration, but normal basal trans-epidermal water loss and skin surface pH as compared to a healthy control group. Histopathology of ichthyosis epidermis showed no acanthosis, and levels of the pro-inflammatory cytokines in the corneal layer did not differ between control and lesional/non-lesional skin of XLI patients. Among the mutations in filaggrin (FLG), kallikrein 7 (KLK7), and SPINK5 genes, the prevalence of KLK7 gene mutations was significantly higher in XLI patients (50%) than in controls (0%), whereas FLG and SPINK5 prevalence was comparable. Korean XLI patients exhibited unimpaired skin barrier function and frequent association with the KLK7 gene polymorphism, which may differentiate them from Western XLI patients.

Matrix disruptions, growth, and degradation of cartilage with impaired sulfation

Diastrophic dysplasia (DTD) is an incurable recessive chondrodysplasia caused by mutations in the SLC26A2 transporter responsible for sulfate uptake by chondrocytes. The mutations cause undersulfation of glycosaminoglycans in cartilage. Studies of dtd mice with a knock-in Slc26a2 mutation showed an unusual progression of the disorder: net undersulfation is mild and normalizing with age, but the articular cartilage degrades with age and bones develop abnormally. To understand underlying mechanisms, we studied newborn dtd mice. We developed, verified and used high-definition infrared hyperspectral imaging of cartilage sections at physiological conditions, to quantify collagen and its orientation, noncollagenous proteins, and chondroitin chains, and their sulfation with 6-μm spatial resolution and without labeling. We found that chondroitin sulfation across the proximal femur cartilage varied dramatically in dtd, but not in the wild type. Corresponding undersulfation of dtd was mild in most regions, but strong in narrow articular and growth plate regions crucial for bone development. This undersulfation correlated with the chondroitin synthesis rate measured via radioactive sulfate incorporation, explaining the sulfation normalization with age. Collagen orientation was reduced, and the reduction correlated with chondroitin undersulfation. Such disorientation involved the layer of collagen covering the articular surface and protecting cartilage from degradation. Malformation of this layer may contribute to the degradation progression with age and to collagen and proteoglycan depletion from the articular region, which we observed in mice already at birth. The results provide clues to in vivo sulfation, DTD treatment, and cartilage growth.

Cholesterol sulfate in human physiology: what's it all about?

Cholesterol sulfate is quantitatively the most important known sterol sulfate in human plasma, where it is present in a concentration that overlaps that of the other abundant circulating steroid sulfate, dehydroepiandrosterone (DHEA) sulfate. Although these sulfolipids have similar production and metabolic clearance rates, they arise from distinct sources and are metabolized by different pathways. While the function of DHEA sulfate remains an enigma, cholesterol sulfate has emerged as an important regulatory molecule. Cholesterol sulfate is a component of cell membranes where it has a stabilizing role, e.g., protecting erythrocytes from osmotic lysis and regulating sperm capacitation. It is present in platelet membranes where it supports platelet adhesion. Cholesterol sulfate can regulate the activity of serine proteases, e.g., those involved in blood clotting, fibrinolysis, and epidermal cell adhesion. As a result of its ability to regulate the activity of selective protein kinase C isoforms and modulate the specificity of phosphatidylinositol 3-kinase, cholesterol sulfate is involved in signal transduction. Cholesterol sulfate functions in keratinocyte differentiation, inducing genes that encode for key components involved in development of the barrier. The accumulating evidence demonstrating a regulatory function for cholesterol sulfate appears solid; the challenge now is to work out the molecular mechanisms whereby this interesting molecule carries out its various roles.

Morphological changes of human erythrocytes induced by cholesterol sulphate

OBJECTIVES

Morphological alterations of human erythrocytes induced by cholesterol sulphate (5-cholesten-3 beta-ol sulphate, CS) were studied.

DESIGN AND METHODS

Influence of CS on red blood cell stability (in isotonic conditions) by simultaneous application of flow cytometry and scanning electron microscopy was studied.

RESULTS

In isotonic medium CS induces erythrocyte size and shape changes in dose-and time-dependent manner. Incubation (in vitro) of erythrocytes with CS concentrations from 4 x 10(-5) mol/dm3 to 8 x 10(-5) mol/dm3 led to a progressive sphero-echinocitic shape transformation accompanied by a cell size decrease. In contrast to this, for CS content equal to 1 x 10(-5) mol/dm3 the maintenance of the normal biconcave shape of red blood cells was observed.

CONCLUSIONS

The results suggest that CS, similarly to numerous evaginating amphiphilic agents, induces a transformation of the erythrocyte normal discoid shape to echinocytic form. This effect may be caused, at least partly, by an asymmetric expansion of the membrane lipid bilayer due to asymmetric distribution of CS incorporated into the membrane. The echinocytic shape transformation of erythrocytes indicated that CS intercalates in the outer hemileaflet of the lipid bilayer leading to membrane externalization.

Higher levels of plasma cholesterol sulfate in patients with liver cirrhosis and hypercholesterolemia

An analytical method for the determination of cholesterol sulfate (CS) in plasma using gas-liquid chromatography was developed. We measured plasma CS concentrations in patients with liver cirrhosis and hypercholesterolemia as examples of disorders that involve aberrations in cholesterol metabolism. Patients with liver cirrhosis had plasma CS concentrations that were significantly higher than those of control subjects (444.6 +/- 51.7 vs. 253.0 +/- 24.6 micrograms/dL, mean +/- SE). The levels of other lipids were lower in cirrhotics, although the differences were not significant. There was no correlation between the levels of CS and sulfated bile acids in cirrhotic patients. CS levels in plasma were also higher in subjects with hypercholesterolemia (413.7 +/- 44.5 micrograms/dL); however, the ratio of CS to total cholesterol (TC) clearly differed between cirrhotics and hypercholesterolemic subjects (1.44 +/- 0.11 x 10(-3) vs. 3.31 +/- 0.63 x 10(-3); P < 0.05). Both in subjects with hypercholesterolemia and in healthy controls, the CS/TC ratio was similar and CS accounted for roughly 0.14% of the TC concentration.

Relationship between cholesterol sulfate and intercellular cohesion of the stratum corneum: demonstration using a push-pull meter and an improved high-performance thin-layer chromatographic separation system of all major stratum corneum lipids

To investigate the role of cholesterol sulfate (CS) as an intercellular glue or cement in the stratum corneum, we compared the relationship between CS levels and magnitude of the intercellular cohesion of the stratum corneum between the palm and the upper arm. Using a push-pull meter, the palm displayed approximately seven times the magnitude of cohesion of the stratum corneum as the upper arm (n = 11). CS and other stratum corneum lipids were extracted from the palm and the upper arm (n = 22) by a cup method and determined by our improved high-performance thin-layer chromatography (HPTLC). Despite a great difference in the magnitude of cohesion (p less than 0.01), CS levels and ratios of CS to ceramides and CS to cholesterol in the stratum corneum showed no significant differences between the palm and the upper arm. Our results suggest that differences in CS cannot account for the differences in cohesion between palm and upper arm.