Steroid sulfatase of human leukocytes and epidermis and the diagnosis of recessive X-linked ichthyosis

Sex steroid synthesis in human skin in situ: the roles of aromatase and steroidogenic acute regulatory protein in the homeostasis of human skin

Sex steroids have been known to play important roles in the homeostasis of human skin, but little is known about their biosyntheses in that tissue. In this study, we characterized the correlation between the concentrations of sex steroids and the expression levels of the factors involved in their synthesis or metabolism in human skin. The expression levels of aromatase (ARO) and steroidogenic acute regulatory protein (StAR) were positively correlated with estrogens and testosterone concentrations, respectively. We demonstrated that estrogen synthesis was markedly decreased by ARO inhibitor and that skins with higher ARO expression had thicker elastic fibers than those with lower ARO expression. While pregnenolone and testosterone concentrations were increased by cholesterol administration to epidermal keratinocytes. Scalp skin with higher StAR expression was cleared to have significantly fewer hair follicles than that with lower expression. Our results suggest that the status of ARO and StAR contribute to estrogen synthesis in situ, especially for the regulation of elastic fiber formation, and to testosterone synthesis, which may be associated with hair growth, respectively.

The role of estrogen-metabolizing enzymes and estrogen receptors in human epidermis

Local estrogen metabolism and its sensitivities in the skin have been also suggested to contribute to skin homeostasis in addition to age- and/or gender-dependent circulating estrogen, even though their local mechanisms have been largely unknown. To characterize their potential correlations, age- and gender-dependencies were evaluated focusing on 5 pivotal estrogen-metabolizing enzymes including aromatase, estrogen sulfotransferase, steroid sulfatase, and 17β-hydroxysteroid dehydrogenases and estrogen receptors (ERα and ERβ) using immunohistochemistry of 100 human skin specimens. When their epidermal expression levels were compared among 7 age groups, ranging from the teens to the seventies, the highest expression in the teens group and the lowest expression in the seventies group were found in the expression of aromatase and ERβ, respectively, while no significant differences between the male and the female groups were found in the immunoreactivities of our interested proteins. Our results suggest that age-related differences in aromatase and ERβ expressions impact epidermal homeostasis.

The skin: an indispensable barrier

The skin forms an effective barrier between the organism and the environment preventing invasion of pathogens and fending off chemical and physical assaults, as well as the unregulated loss of water and solutes. In this review we provide an overview of several components of the physical barrier, explaining how barrier function is regulated and altered in dermatoses. The physical barrier is mainly localized in the stratum corneum (SC) and consists of protein-enriched cells (corneocytes with cornified envelope and cytoskeletal elements, as well as corneodesmosomes) and lipid-enriched intercellular domains. The nucleated epidermis also contributes to the barrier through tight, gap and adherens junctions, as well as through desmosomes and cytoskeletal elements. During epidermal differentiation lipids are synthesized in the keratinocytes and extruded into the extracellular domains, where they form extracellular lipid-enriched layers. The cornified cell envelope, a tough protein/lipid polymer structure, resides below the cytoplasmic membrane on the exterior of the corneocytes. Ceramides A and B are covalently bound to cornified envelope proteins and form the backbone for the subsequent addition of free ceramides, free fatty acids and cholesterol in the SC. Filaggrin is cross-linked to the cornified envelope and aggregates keratin filaments into macrofibrils. Formation and maintenance of barrier function is influenced by cytokines, 3',5'-cyclic adenosine monophosphate and calcium. Changes in epidermal differentiation and lipid composition lead to a disturbed skin barrier, which allows the entry of environmental allergens, immunological reaction and inflammation in atopic dermatitis. A disturbed skin barrier is important for the pathogenesis of contact dermatitis, ichthyosis, psoriasis and atopic dermatitis.

Association of the steroid sulfatase (STS) gene with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is the most common behavioral disorder affecting children worldwide. The male bias in the prevalence of the disorder, suggests that some susceptibility genes may lie on the X chromosome. In this study we present evidence for a role of the X-linked steroid sulfatase (STS) gene and neurosteroids in the development of ADHD. Previously it has been observed that probands with ADHD have lower serum concentrations of the neurosteroids DHEA, which is synthesized from DHEA-S by STS. In further support, boys that suffer from XLI, a skin disorder caused by the deletion of the STS gene, have higher rates of ADHD, in particular the inattentive subtype. In a moderately sized sample of ADHD families (N = 384), we genotyped seven single nucleotide polymorphisms, tagging the entire gene. TDT analysis of the data yielded two polymorphisms that were significantly associated with ADHD (rs2770112-Transmitted: 71 Not Transmitted; 48; rs12861247-Transmitted: 43 Not Transmitted: 21), located towards the 5' end of the gene (P < 0.05). We conclude that the STS gene may play a role in susceptibility for ADHD, and that the neurosteroids pathways should be investigated further to access their potential contribution in susceptibility to the disorder.

Steroid sulfatase: molecular biology, regulation, and inhibition

Steroid sulfatase (STS) is responsible for the hydrolysis of aryl and alkyl steroid sulfates and therefore has a pivotal role in regulating the formation of biologically active steroids. The enzyme is widely distributed throughout the body, and its action is implicated in physiological processes and pathological conditions. The crystal structure of the enzyme has been resolved, but relatively little is known about what regulates its expression or activity. Research into the control and inhibition of this enzyme has been stimulated by its important role in supporting the growth of hormone-dependent tumors of the breast and prostate. STS is responsible for the hydrolysis of estrone sulfate and dehydroepiandrosterone sulfate to estrone and dehydroepiandrosterone, respectively, both of which can be converted to steroids with estrogenic properties (i.e., estradiol and androstenediol) that can stimulate tumor growth. STS expression is increased in breast tumors and has prognostic significance. The role of STS in supporting tumor growth prompted the development of potent STS inhibitors. Several steroidal and nonsteroidal STS inhibitors are now available, with the irreversible type of inhibitor having a phenol sulfamate ester as its active pharmacophore. One such inhibitor, 667 COUMATE, has now entered a phase I trial in postmenopausal women with breast cancer. The skin is also an important site of STS activity, and deficiency of this enzyme is associated with X-linked ichthyosis. STS may also be involved in regulating part of the immune response and some aspects of cognitive function. The development of potent STS inhibitors will allow investigation of the role of this enzyme in physiological and pathological processes.

6-[2-(adamantylidene)-hydroxybenzoxazole]-O-sulfamate, a steroid sulfatase inhibitor for the treatment of androgen- and estrogen-dependent diseases

Steroid sulfatase (STS) offers a new target for the treatment of steroid hormone-dependent diseases, such as breast and prostate cancer and androgen-dependent skin diseases. We here characterize a novel non-estrogenic inhibitor of the enzyme, namely 6-[2-(adamantylidene)-hydroxybenzoxazole]-O-sulfamate (AHBS), with special attention to its potential use in the treatment of acne. The compound blocks STS activity in homogenates of human skin with IC(50)=16 nM. Following a single oral dose (5 mg/kg) in rats, the compound blocks STS in the skin by 95% at 8 h, followed by recovery of activity over 5 days. Following topical application to the skin, both in vitro and in vivo, AHBS passes through the stratum corneum leading to inhibition of STS activity in the dermal compartment with rapid onset and long duration. Topical application of AHBS to Göttingen minipigs for a period of 2 weeks does not induce symptoms of ichthyosis as seen in STS-deficient human subjects, but leads to a reduction of sebum secretion to the skin surface. Based on these data, clinical studies with AHBS in acne patients are warranted, in order to verify the hypothesis on the importance of the sulfatase pathway in androgen-dependent skin diseases.

Steroid sulfatase (STS) expression in the human temporal lobe: enzyme activity, mRNA expression and immunohistochemistry study

Dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) are suggested to be important neurosteroids. We investigated steroid sulfatase (STS) in human temporal lobe biopsies in the context of possible cerebral DHEA(S) de novo biosynthesis. Formation of DHEA(S) in mature human brain tissue has not yet been studied. 17 alpha-Hydroxylase/C17-20-lyase and hydroxysteroid sulfotransferase catalyze the formation of DHEA from pregnenolone and the subsequent sulfoconjugation, respectively. Neither their mRNA nor activity were detected, indicating that DHEA(S) are not produced within the human temporal lobe. Conversely, strong activity and mRNA expression of DHEAS desulfating STS was found, twice as high in cerebral neocortex than in subcortical white matter. Cerebral STS resembled the characteristics of the known placental enzyme. Immunohistochemistry revealed STS in adult cortical neurons as well as in fetal and adult Cajal-Retzius cells. Organic anion transporting proteins OATP-A, -B, -D, and -E showed high mRNA expression levels with distinct patterns in cerebral neocortex and subcortical white matter. Although it is not clear whether they are expressed at the blood-brain barrier and facilitate an influx rather than an efflux, they might well be involved in the transport of steroid sulfates from the blood. Therefore, we hypothesize that DHEAS and/or other sulfated 3beta-hydroxysteroids might enter the human temporal lobe from the circulation where they would be readily converted via neuronal STS activity.

Low or absent unconjugated estriol in pregnancy: an indicator for steroid sulfatase deficiency detectable by fluorescence in situ hybridization and biochemical analysis

It has been previously reported that a low or absent maternal serum unconjugated estriol (uE3) level is associated with placental steroid sulfatase (STS) deficiency. Here we report a correlation between patients who present with a very low or absent maternal serum uE3 and a deletion of the STS gene as assessed by fluorescence in situ hybridization (FISH). We studied nine prenatal cases that presented to the clinical laboratory with an abnormal triple screen, specifically low or absent maternal serum uE3 and a 46,XY karyotype. FISH analysis showed complete deletion of a probe containing the STS gene in six cases and one case had a partial deletion (reduced but not absent signal). The remaining two cases were not deleted for the STS probe. All mothers tested whose fetus showed a deletion were shown to be STS deletion carriers using FISH. Biochemical analysis was performed on 7/9 prenatal specimens. All fetuses deleted for the STS probe were also found to be deficient for STS by biochemical analysis of cultured amniotic fluid (5/5). Of the two fetuses not deleted for the STS probe, one was deficient for STS activity, while the other had a normal result. The abnormal result of enzyme deficiency by biochemical analysis in a non-deletion case likely represents a mutation in the STS gene, not detectable by this FISH assay. Postnatal FISH confirmation of the STS deletion was performed in 1/7 cases. Clinical follow-up was available for 4/9 cases following birth.

Mutation report: a novel partial deletion of exons 2-10 of the STS gene in recessive X-linked ichthyosis

X-linked ichthyosis is an inherited disease due to steroid sulfatase deficiency. Onset is at birth or early after birth with dark, regular, and adherent scales of skin. Approximately 85%-90% of X-linked ichthyosis patients have large deletions of the STS gene and flanking sequences. Three patients have been identified with partial deletions of the gene. Two deletions have been found at the 3' extreme and the other one implicating exons 2-5. This study describes a novel partial deletion of the STS gene in an X-linked ichthyosis patient. The subject was classified through steroid sulfatase assay in leukocytes using 7-[3H]-dehydroepiandrosterone sulfate as a substrate. Exons 1, 2, 5, and 7-10, and 3' flanking sequences DXS1131, DXS1133, DXS237, DXS1132, DXF22S1, and DXS278 of the STS gene were analyzed through polymerase chain reaction. The DNA analysis showed that exon 1 and 3' flanking sequences from DXS237 to DXS278 were present. In this study we report the fourth partial deletion of the STS gene and the first spanning exons 2-10 in X-linked ichthyosis patients.

X-linked ichthyosis: an update

X-linked ichthyosis is a genetic disorder of keratinization characterized by a generalized desquamation of large, adherent, dark brown scales. Extracutaneous manifestations include corneal opacity and cryptorchidism. Since 1978 it has been known that a deficit in steroid sulphatase enzyme (STS) is responsible for the abnormal cutaneous scaling, although the exact physiological mechanism remains uncertain. The STS gene has been mapped to the distal part of the short arm of the X chromosome. Interestingly, this region escapes X chromosome inactivation and has the highest ratio of chromosomal deletions among all genetic disorders, complete deletions having been found in up to 90% of patients. Diagnosis of patients with X-linked ichthyosis and female carriers is based on biochemical and genetic analysis. The latter currently seems to be the most accurate method in the majority of cases.

X-linked ichthyosis in Mexico: high frequency of deletions in the steroid sulfatase encoding gene

The present study analyzes the frequency of molecular deletions in the steroid sulfatase (STS) encoding gene in a sample of 50 Mexican subjects with biochemical diagnosis of X-linked ichthyosis (XLI). To establish the correct diagnosis, STS activity was determined in leukocytes using 7-(3)H-dehydroepiandrosterone sulfate as the substrate. No amplification of the 3' and 5' ends of the STS gene by PCR was detected in the DNA of 49 patients, whereas only one sample of 50 presented a normal amplification. This report shows a very high frequency of deletions in the human STS encoding gene in a representative sample of the Mexican population, and it defines the characteristics of XLI in patients whose STS gene has a complete deletion as a major molecular defect.

Steroid sulfatase activity in osteoblast cells

We have demonstrated steroid sulfatase activity in osteoblast cells and characteristics of the enzyme were also investigated. Cell free homogenate of rat osteoblast cell line, UMR106-01 and human osteoblast cell lines, MG-63, HOS were incubated with [3H] dehydroepiandrosterone-sulfate (DHEA-sulfate) or [3H] estrone-sulfate (E1-sulfate). The formation of DHEA or E1 from the corresponding substrate was identified by crystallization to constant specific activity. Michaelis constant (K(m)) for DHEA-sulfate was estimated as 2.1 x 10(-8)M in UMR106-01, 7.4 x 10(-7)M in MG-63, 5.8 x 10(-7)M in HOS and that for E1-sulfate was 4.1 x 10(-7)M, 3.0 x 10(-7)M, 9.8 x 10(-7)M, respectively. The expression of steroid sulfatase messenger ribonucleic acid in human osteoblast cells, HOS and MG-63 was first demonstrated by reverse transcription-polymerase chain reaction. The existence of steroid sulfatase in human and rat osteoblast cells suggests that osteoblast cells have the capacity to convert circulating sulfo-conjugated steroids to more active androgens and estrogens. This may indicate an important role of bone in facilitating hormonal action.

Hair keratinization in health and disease

The cells of the epidermis and its derivative, the hair follicle, undergo processes of terminal differentiation that involves the synthesis and assembly of classes of protein and enzymes to form the stratum corneum of the epidermis, and the hair fiber and its cuticle. Using genetic linkage and DNA sequencing methods, we now know that mutations in several genes encoding epidermal keratins or a transglutaminase enzyme cause ichthyosis-related diseases. Similar methods have now suggested that mutations in hair keratin genes underlie some cases of monilethrix, and a deficiency in a cuticle lipid metabolizing enzyme causes maple syrup urine disease. It is to be expected that further application of these methods will elucidate the molecular bases of other genetic hair diseases.

Steroid sulphatase deficiency: identification of heterozygotes using hydrolysis of dehydroepiandrosterone sulphate by peripheral leucocytes

Diagnosis of X-linked recessive ichthyosis, which is expressed only in males, can readily be made by measurement of leucocyte steroid sulphatase activity. However, because the gene for steroid sulphatase activity partly escapes from the process of X-chromosome inactivation associated with gene dosage compensation, identification of heterozygotes (females) is more difficult. We have measured the steroid sulphatase (by hydrolysis of dehydroepiandrosterone sulphate) and beta-glucuronidase (by hydrolysis of methylumbelliferyl glucuronide) activities in leucocytes from 18 heterozygotes, 100 normal females, 100 normal males and 11 affected subjects. When the ratio of the activities of steroid sulphatase and beta-glucuronidase in mixed leucocytes was plotted as a function of the steroid sulphatase activity, 85% heterozygotes were distinguished from normal females. Measurement of steroid sulphatase activity alone with these cells enabled identification of 78% heterozygotes. Measurements on mononuclear leucocytes were much less effective. Thrombocytes showed 1% of the steroid sulphatase activity of leucocytes. In females, leucocyte steroid sulphatase activity was independent of the stage of the ovarian cycle at which the cells were collected.

Cholesterol sulfate is not degraded but does not accumulate in Epstein-Barr virus-transformed lymphoid cells from patients with X-linked ichthyosis

The metabolism of cholesterol sulfate (CS) was investigated in immortalized, Epstein-Barr virus-transformed lymphoid cell lines derived from normal individuals and patients affected with recessive X-linked ichthyosis (XLI). Normal lymphoid cells expressed arylsulfatase C and steroid sulfatase (including cholesterol sulfatase) activities, and these two sulfohydrolases showed the same enzyme properties as in other human cells, e.g., leukocytes or skin fibroblasts. XLI-derived lymphoid cell lines exhibited extremely deficient activity of both arylsulfatase C and steroid sulfatase. While normal and XLI intact, living lymphoid cells could take up exogenous radiolabelled CS through a non-receptor-mediated process. XLI cells were completely unable to degrade CS to cholesterol. However, despite their defect in CS degradation, steroid sulfatase-deficient cells did not accumulate CS because of outflux of this sterol. The potential implications of these findings to the pathogenesis of increased CS content in plasma and epidermis of XLI patients are discussed. This study also demonstrates that immortalized lymphoid cell lines may represent a useful experimental model system for the study of XLI.

Clinico-epidemiological profile of ichthyosis in south Indian patients

A high frequency rate of hereditary ichthyosis (141.89 per 1000) was detected in a 1029 member South Indian study population selected at random from the skin outpatients of a teaching hospital. An age and sex matched control population screened from the medical and pediatric outpatients of the same institute recorded the incidence of ichthyosis vulgaris as 150 per 1000 population which is even higher.

A clinical and genetic study of X-linked recessive ichthyosis and contiguous gene defects

X-linked recessive ichthyosis (XLI) is caused by a deletion, or mutation, of the steroid sulphatase gene on the distal short arm of the X chromosome (Xp22.3). This region of the X chromosome is particularly susceptible to deletions. Such deletions can occasionally extend to involve neighbouring genes, causing a contiguous gene defect. Therefore, XLI may be associated with Kallmann's syndrome (KS), mental retardation, X-linked recessive chondrodysplasia punctata and short stature. We have reviewed 33 patients with XLI. Nine showed evidence of contiguous gene defects. A further four had neurological deficit sustained at the time of birth. This study highlights the importance of screening patients with X-linked recessive ichthyosis for neighbouring genetic disorders and, in particular, the early identification of KS, as delay in diagnosis may lead to infertility and osteoporosis. Parents should be warned about possible obstetric complications due to prolonged labour in future pregnancies.

Steroid sulfatase deficiency in Japanese patients: characterization of X-linked ichthyosis by using polymerase chain reaction

X-Linked ichthyosis (XLI) due to deficiency of steroid sulfatase (STS) of which gene consists of 10 exons is an inherited skin disorder. The gene, mRNA and protein of STS were examined in six Japanese patients with XLI. Neither the mRNA nor the enzyme protein was detected in a patient. The results of Southern analysis using STS cDNA as a probe indicated that all the patients examined exhibited large deletions of the STS gene. When exon 1 and the exon 10 of the STS gene were amplified by polymerase chain reaction using patients' genomic DNA as templates, no product was detected in all the patients examined. These observations suggest that most XLI in Japanese patients is caused by an extensive deletion of the STS gene as was demonstrated in Caucasian patients. The PCR method in the present study is useful for the diagnosis of XLI in prenatal and postnatal subjects.

Enzymatic diagnosis of steroid sulfatase deficiency by high performance liquid chromatography

We established a reversed phase high performance liquid chromatographic (HPLC) method of assaying lymphocyte steroid sulfatase activity using estrone sulfate as the substrate. Application of this method for diagnosis of 8 patients allowed us to clearly distinguish the patients from the normal controls. This method is simpler and less expensive than the method previously reported, since neither radioisotope labeled substrates nor radioisotope facilities are required. We consider it to be easily used and widely available in most clinical laboratories.

Amniotic fluid embolism and leukotrienes--the role of amniotic fluid surfactant in leukotriene production

Surfactant rich lipid (lipid) was extracted from cell free 10,000 x g pellets of amniotic fluid. White blood cells (WBC) were isolated from human donors. 36 x 10(7) WBC and 5 g rabbit lung were incubated with pretreated lipid or dipalmitoyl lecithin (lecithin). Leukotrienes (LTs) were identified by high performance liquid chromatography (HPLC) and bioassay, and quantified by radioimmunoassay. Peaks of LTC4 and LTD4 on HPLC and guinea-pig ileum contraction could be identified in lipid and lecithin groups, but not in the control group. LTC4 production by lipid and lecithin groups was significantly higher than that by the control group. An involvement of amniotic fluid surfactant in leukotriene production is suggested.

Arylsulfatases A and B in EBV-transformed lymphoid cell lines: studies on their molecular forms in cells from patients with inborn sulfatase deficiencies. Comparative diagnostic value of enzymatic assays

The enzyme activity of arylsulfatase A and arylsulfatase B was studied in Epstein-Barr virus-transformed lymphoid cell lines established from control individuals and patients affected with metachromatic leukodystrophy, mucopolysaccharidosis type VI (or Maroteaux-Lamy syndrome) and multiple sulfatase deficiency. Lymphoid cells derived from patients with metachromatic leukodystrophy showed a severe deficiency in cerebroside sulfatase activity, as measured using radiolabelled sulfatide, but some residual activity of arylsulfatase A when measured with the chromogenic substrate, para-nitrocatechol sulfate. Lymphoid cells from mucopolysaccharidosis type VI had virtually no arylsulfatase B activity. In cells from patients with multiple sulfatase deficiency, the activities of lysosomal sulfatases as well as steroid sulfatase were deficient. Study of the molecular forms of arylsulfatases confirmed the complete deficiency of arylsulfatase A and arylsulfatase B activities in metachromatic leukodystrophy and mucopolysaccharidosis type VI lymphoid cells, respectively. The arylsulfatase A defect in metachromatic leukodys-lymphoid cells, respectively. The arylsulfatase A defect in metachromatic leukodystrophy cells could be demonstrated on focused fractions even using the artificial substrates, para-nitrocatechol sulfate and 4-methylumbelliferyl sulfate. To investigate the discrepancy of the arylsulfatase A activity data observed between whole cell homogenates and focused fractions when using the synthetic substrates, assays were tentatively performed for optimizing the determination of arylsulfatase A on crude homogenates of lymphoid cells. Although this work has indicated methodological limitations of the enzymatic assay of arylsulfatase A in lymphoid cells using methylumbelliferyl sulfate, it emphasizes the validity of lymphoid cell lines as an experimental model for the study of inborn deficiencies of arylsulfatases A and B.

All about ichthyosis

From "alligator people" to "porcupine boys," the ichthyoses have been a distinctly recognizable entity for thousands of years. Recent improvements in biochemical and genetic research have allowed more scientific delineation of this class of diseases. This article covers the latest in pathophysiology, the major classes of ichthyoses, many of the newer minor ones, prenatal diagnosis, and treatment options.

Steroid sulfatase activity in nails: screening for X-linked ichthyosis

X-linked ichthyosis is generally diagnosed by a deficiency of steroid sulfatase activity in fibroblasts or leukocytes. We established a method of assaying nail steroid sulfatase activity for diagnostic use. Nail samples were easy to collect and handle, and satisfied the screening criteria of accuracy, sensitivity, and stability. The detergents Tween 20 and Triton-X 100, which enhance nail STS activity, enabled us to assay the activity with small amounts of nails. The detergent-facilitated assay was also suitable for use with pediatric patients, from whom small amounts of nails were collected.

Lecithins enhance leukotriene production from white cells

36 x 10(7) WBC were isolated from 120 ml heparinized venous blood by 5% dextran T-500 sedimentation. 20 mg egg lecithin and 20 mg dipalmitoyl lecithin were respectively pretreated in 2 ml 0.15 M Tris buffer by vibration and sonication. WBC were incubated with the pretreated lecithins for 20 min. Leukotrienes (LTs) were identified by HPLC and bioassay, and quantified with an RIA Kit. Crude incubation medium of both lecithin groups caused guinea pig ileum contractions which were antagonized with FPL55712. Incubation media were partially purified with Bond elut C18. Purified samples of both lecithin groups showed LTC4 and LTD4 peaks on HPLC. LTC4 production (pg/10(7) WBC, M +/- SD) was 194.5 +/- 61.7 (n = 5) in control group, 348.9 +/- 95.4 (n = 6) in dipalmitoyl lecithin group, 543.8 +/- 105.6 (n = 6) in egg lecithin group and 105.62 +/- 63.2 (n = 6) in AA-861 + dipalmitoyl lecithin group. LTC4 production of both lecithin groups was significantly higher than that of control group (P less than 0.01 in dipalmitoyl lecithin group and P less than 0.001 in egg lecithin group). Both egg lecithin and dipalmitoyl lecithin enhanced LT production from WBC. LT production was suppressed in the presence of AA-861. The mechanism of the enhancement in LT production is unclear, but these lecithins are apparently not substrates because dipalmitoyl lecithin contains no arachidonic acid.

Detection of carriers for X-linked ichthyosis by Southern blot analysis and identification of one family with a de novo mutation

Scaling in patients with recessive X-linked ichthyosis is caused by lack of activity of the enzyme steroid sulfatase. In approximately 90% of kindreds, this lack is the result of a DNA deletion large enough to eliminate the coding region completely. We have used Southern blot hybridization of DNA isolated from peripheral blood leukocytes to measure gene dosage of the steroid sulfatase gene. This readily detects a half-normal dosage in women who are carriers and therefore can be used to diagnose the carrier status of female relatives of 90% of patients with the disease. We have found one family in whom the deletion arose on an allele inherited from the proband's clinically normal maternal grandfather.

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 for 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 keratinized tissues in RXLI patients, were examined for CS levels. The results demonstrated significantly elevated CS levels in both tissues in RXLI patients (P less than 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.

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

A 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 preoperative 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 derivative for the GLC analysis on dual 2m 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.

Microanalytical screening of all major stratum corneum lipids by sequential high-performance thin-layer chromatography

For rapid and sensitive screening of lipid biochemical abnormalities of scaling skin disorders a sequential, one-dimensional high-performance thin-layer chromatographic method (HPTLC) has been developed. All major human stratum corneum lipid classes, i.e., cholesterol sulfate, glucosylceramides, six major ceramide fractions, free sterols, free fatty acids, triglycerides, sterol esters, squalene, and n-alkanes, are separated and quantitated after a stepwise development of a single silica gel 60 HPTLC-plate using three consecutive solvent systems. Reproducible results have been obtained by degradative charring as well as fluorescence detection. By fluorescence detection the method is particularly suitable for the determination of minor amounts of cholesterol sulfate and other sterols.

X-linked ichthyosis and ichthyosis vulgaris: comparison of their clinical features based on biochemical analysis

Thirty cases of X-linked ichthyosis (XLI) and 32 cases of ichthyosis vulgaris (IV) were diagnosed by measuring the steroid sulphatase activity of peripheral blood lymphocytes or the electrophoretic mobility of serum LDL or both. The clinical features of the two conditions were then compared. In both diseases 60-66% of patients had a family history of the condition. Ichthyosis was noted at birth or immediately afterwards in 59% of the patients with XLI while it appeared in infancy in 68% of those with IV. Scales were mostly large and brown or dark brown in patients with XLI, while the majority of patients with IV had small brown or light brown scales. The distribution of the ichthyotic lesions differed in the two types of ichthyosis. On the trunk, the abdomen was more severely involved than the back in 63% of the cases with the XLI, whereas the back was more scaly than the abdomen in 44% of those with IV. On the extremities, the extensor surface was more severely affected than the flexor surface in both types. X-linked ichthyosis was characterized by the presence of lesions in the pre-auricular area, which were found in 93% of the cases with XLI, while only 17% of the IV patients had ichthyotic lesions at this site. Involvement of the preauricular area could be an important clinical feature for distinguishing XLI from IV.

Characterization of low-density lipoproteins from patients with recessive X-linked ichthyosis

We investigated lipoprotein metabolism in 14 patients with recessive X-linked ichthyosis (RXLI), a metabolic disease characterized by scaly skin, corneal opacity and steroid sulfatase deficiency. Plasma total cholesterol (TC) levels ranged from normal to slightly low (mean +/- SD: 156 +/- 28 mg/dl). Four patients showed a mild or moderate elevation of plasma triglyceride (TG) levels ranging from 150 to 365 mg/dl. The apoprotein B (apo B) to TC ratio was higher than in normal controls (0.63 +/- 0.11 vs. 0.52 +/- 0.07, P less than 0.01), while plasma apoB levels were within the normal range (99 +/- 17 mg/dl). Polyacrylamide gel electrophoretic mobility of low-density lipoprotein (LDL) was markedly increased in all patients, and further analyses showed that this finding was not due to a change in the particle size of the LDL but to an increased content of cholesterol sulfate (1.0-2.3% of the LDL-cholesterol content). In addition to the alteration of electrophoretic mobility, marked changes in the lipid and apoprotein compositions of the LDL fraction were observed; cholesterol ester content in LDL (LDL-CE) was significantly lower than that of control subjects (37 +/- 4% vs. 41 +/- 2% of total lipids, P less than 0.01), while the triglyceride content (LDL-TG) and apo B to cholesterol ratios in LDL were significantly higher than those of controls (18 +/- 7 vs. 10 +/- 2, P less than 0.001; 1.21 +/- 0.19 vs. 0.73 +/- 0.05, P less than 0.001, respectively). This anionized LDL, in which cholesterol sulfate was increased, was shown to bind to the LDL receptor of fibroblasts to much the same extent as normal LDL. In conclusion, the increase in cholesterol sulfate in LDL fraction not only alters the electrophoretic moiety but also the relative contents of apoB, cholesterol, and triglyceride in the lipoprotein. It does not change the affinity of LDL for the LDL receptor.

Metabolism of 3H-dehydroepiandrosterone sulphate by subjects with steroid sulphatase deficiency

Patients with steroid sulphatase deficiency develop ichthyosis with accumulation of cholesterol sulphate in plasma and in the stratum corneum. The present study was undertaken to determine whether desulphation of the C19 steroid DHEAS is also impaired. The mean plasma concentrations of DHEA and androstenedione were significantly lower for patients than for controls (p less than 0.02 and 0.001) while the mean concentration of DHEAS was higher (p less than 0.002). Following intravenous administration of 3H-DHEAS, one patient failed to desulphate 3H-DHEAS as evidenced by an absence of urinary 3H-glucuronides. A second produced normal amounts of urinary 3H-glucuronides (indicative of desulphation capacity) in a baseline study but did not desulphate 3H-DHEAS following ampicillin treatment to alter gut microflora. A third patient had consistent sulphatase activity with and without ampicillin.

Cloning of a cDNA for steroid sulfatase: frequent occurrence of gene deletions in patients with recessive X chromosome-linked ichthyosis

A human steroid sulfatase (steryl-sulfatase; steryl-sulfate sulfohydrolase, EC 3.1.6.2) cDNA 2.4 kilobases long was isolated from a human placental lambda gt11 cDNA expression library. The library was screened with monospecific rabbit antibodies elicited by injection of steroid sulfatase protein purified from human placentas. Hybridization of the cDNA with EcoRI-digested genomic DNA indicated that patients from 14 of 15 apparently unrelated families have gross deletions of the gene for steroid sulfatase. One patient had genomic DNA fragments that were identical to those from normal individuals, indicating the absence of any major deletions as the cause of his lack of steroid sulfatase enzyme activity.

Simplified method of determination of serum cholesterol sulfate by reverse phase thin-layer chromatography

A new method for determination of cholesterol sulfate (CS) and dehydroepiandrosterone sulfate (DHEAS) from 1 ml serum by reverse phase thin-layer chromatography (TLC) is described. The method comprises an isolation step of sulfated steroids by means of octadecylsilane-bonded (C18) reverse phase column chromatography, a solvolysis step for desulfation of sulfated steroids, and a C18 TLC step for measurement on a photodensitometer. This method is much simpler and more rapid than the methods previously reported, since neither a radioisotope is needed, nor any steps of saponification, derivatization, tedious scraping from a TLC plate, and time-consuming conventional column chromatography are not required. The present method allowed us to distinguish recessive X-linked ichthyosis (RXLI) very easily from ichthyosis vulgaris (IV) by the size and gradation of clearly visible blue chromogen derived from CS on a TLC plate in RXLI. By photodensitometer scanning, the CS levels in patients with RXLI were about 10 times higher than those of patients with IV and healthy subjects, whereas the DHEAS level was normal in the RXLI patients. The present simplified method proved to be useful in diagnosis of RXLI.

Steroid sulphatase levels are higher in males than in females of the root vole (Microtus oeconomus). Yet another rodent with an active Y-linked allele?

Steroid sulfatase (STS; EC 3.1.6.2) levels were assayed in cultured fibroblasts of root voles captured in the wild. Four independent experiments were performed using two different substrates (DHEAS and E1S). Evidence is presented that in this species, STS levels are significantly higher in males than in females (ratio 1.6:1). We discuss our findings on a comparative basis and suggest that in the root vole the STS gene(s) is X- and Y-linked (as in the mouse) and that it is subject to X-inactivation, or partially so, on one of the X chromosomes in the female.

Keratinocytes cultured from subjects with ichthyosis vulgaris are phenotypically abnormal

Ichthyosis vulgaris (IV) is an autosomal dominant, scaling disorder in which keratohyaline granules and filaggrin are reduced in or absent from the epidermis of affected individuals. Morphologic and biochemical markers of epidermal differentiation were studied in keratinocytes cultured from clinically unaffected skin of patients with IV, from clinically unaffected skin of an obligate gene carrier, and from normal skin of unaffected family members and an adult volunteer. Cultured keratinocytes from affected subjects formed thickened layers of scaly cells that failed to react with monoclonal antibody to filaggrin. In contrast, normal cells contained many large, immunoreactive granules. Electron microscopy confirmed the absence of keratohyaline granules in affected cells and the presence of large keratohyaline granules in normal cells. Immunoblot analysis of keratinocyte extracts from subjects with ichthyosis showed that profilaggrin was absent, but no differences in keratins were detected between affected and control cells. For all parameters, findings in cells of the clinically unaffected obligate gene carrier were intermediate between those from affected patients and controls. We conclude that keratinocytes cultured from patients with IV maintain structural and biochemical phenotypic characteristics of the disease in vitro.

Tissue-specific expression of human arylsulfatase-C isozymes and steroid sulfatase

Steroid sulfatase (STS; E.C.3.1.6.2), which acts on 3-hydroxysteroid sulfates, and arylsulfatase-C (ARC; E.C.3.1.6.1), assayed with aromatic artificial substrates, are both membrane-bound, microsomal enzymes with alkaline pH optima. Although they copurify during preparation and their gene loci are mapped to the short arm of the human X chromosome where they appear to have escaped from X inactivation, it has not been settled whether STS and ARC are the same enzyme or not. Recent work from our laboratory has shown that ARC exists in two electrophoretically distinct forms in human fibroblasts. We now report that these two forms--the faster migrating (F) and more slowly migrating (S)--occur in human tissues. Each of 11 human tissue types from 10 subjects showed a consistent pattern of ARC isozymes. Thyroid, heart, spleen, skeletal muscle, and adrenal tissue mainly had the S form. In contrast, kidney, liver, and pancreas tissue had mainly the F form, while gonadal, lung, and intestinal tissue had both the S and the F forms. The question of escape of their gene locus from X-chromosome inactivation was examined by comparing the specific activities of ARC and STS in male-derived vis-à-vis female-derived tissues. The majority of the tissues did not show any significant difference in these activities between the sexes, the exceptions being heart muscle, gonadal, and kidney tissue. None showed the 1:2 ratio between male- and female-derived tissues expected of a locus that had escaped X inactivation. The question of identity between ARC and STS was examined by comparing the ratios of their activities in these tissue types: if the enzymes were identical, the ratios of their activities should have remained constant across the different tissue types. It was thus shown that ARC activity varied by as much as 100-fold, depending on the ARC isozymic pattern of the tissue. STS, measured as estrone sulfatase and dehydroepiandrosterone sulfatase, did not show similar variations. This provides further evidence that ARC activity is not necessarily identical to that of STS.

Arylsulphatase C activity in leukocytes of patients and carriers of X-linked ichthyosis

In Triton X-100 solubilized leukocytes of 17 patients and 8 obligate carriers of X-linked recessive ichthyosis (XLI) the activity of arylsulphatase C (ASC) was determined and expressed as the ratio to beta-galactosidase activity. The ASC/beta-gal ratio of XLI patients is markedly decreased (range 0.07-0.48) in comparison to the corresponding control group of males (range 1.3-2.7). The enzyme ratios of 8 obligate carriers of XLI are decreased (range 0.90-1.9) in comparison to the normal females (2.13-5.52). These results indicate that the determination of the enzyme ratio of ASC/beta-gal in Triton X-100 solubilized leukocytes is a sensitive test for biochemical identification of patients and probably of carriers of XLI.

Regulation of serum testosterone in men with steroid sulfatase deficiency: response to human chorionic gonadotropin

Human chorionic gonadotropin (hCG; 5000 IU) was administered to 6 control men and 6 patients with recessive x-linked ichthyosis (RXLI) with verified 3 beta-hydroxysteroid sulfate sulfatase (3 beta-HSS) deficiency in their skin biopsy samples. Concentrations of steroids and their sulfate conjugates were determined in peripheral serum specimens collected a day before and 4 days after hCG administration. Testosterone concentrations were identical in patients and controls. Baseline serum LH concentrations were also identical in the 2 groups showing that there were no major differences in the regulation of the hypothalamic-pituitary-gonadal axis. The significantly increased (31-82%) serum concentrations of sulfated pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone and 5-androstene-3 beta,17 beta-diol in patients compared with controls indicated that their circulating concentrations were regulated by 3 beta-HSS. This is in line with the fact that the baseline concentrations of the same unconjugated steroids were significantly lower (32-90%) in patients with RXLI, suggesting that a proportion of these circulating steroids were derived from the corresponding sulfated precursors. The response patterns and actual concentrations of testosterone, 17-hydroxyprogesterone and estradiol were similar in the patients and the controls after hCG. The decreased concentrations of testosterone sulfated at carbon 17 under baseline conditions and after hCG in patients with RXLI remains enigmatic. In conclusion, testosterone production and the response to hCG seem to be identical in patients with RXLI and controls despite the fact that significant differences were observed in the circulating concentrations of several unconjugated and sulfated testosterone precursors.

A new syndrome of anosmia, ichthyosis, hypogonadism, and various neurological manifestations with deficiency of steroid sulfatase and arylsulfatase C

We describe a family consisting of 3 affected men with congenital ichthyosis, anosmia, hypogonadism, nystagmus with decreased visual acuity, strabismus, hypopigmentation of the iris, and mirror movements of the hands and feet. Two of them had limitation of ocular movement and unilateral renal agenesis or hypoplasia. The condition appears to be inherited as an X-linked recessive trait. Clinical, pathological, and biochemical evaluations were compatible with a diagnosis of X-linked ichthyosis. Steroid sulfatase and arylsulfatase C activities in leukocytes and fibroblasts were markedly diminished in the affected patients. Their hypogonadism was due to decreased luteinizing hormone-releasing hormone secretion (hypogonadotropic). Hyposecretion of antidiuretic hormone was also recognized. Chromosome analysis of leukocytes and skin fibroblasts revealed a normal 46,XY male karyotype in all of the patients.

Partial lyonisation of steroid sulphatase gene in single hair roots

Steroid sulphatase (STS) activity was measured in single hair roots from 9 patients with X-linked ichthyosis, 7 obligate heterozygotes, 12 male controls and 12 female controls. STS activity was deficient (less than 0.3 pmol dehydroepiandrosterone (DHEA) in 5 h per hair root) in the patients as compared to male controls (4.6 +/- 1.8 pmol DHEA in 5 h per hair root). All single hair roots from obligate heterozygotes showed STS activity (3.0 +/- 0.9 pmol DHEA in 5 h per hair root). Female controls had a significantly higher STS activity (6.0 +/- 1.8 pmol DHEA in 5 h per hair root) than male controls (p less than 0.05) and heterozygotes (p less than 0.001). Both the female-male sex ratio of control STS activity (1.3) and the absence of STS-deficient hair roots in heterozygotes confirm previous evidence for incomplete lyonisation of the X-linked steroid sulphatase gene.

Detection of heterozygotes of X-linked ichthyosis by measuring steroid sulphatase activity of lymphocytes. Mode of inheritance in three families

Steroid sulphatase activity in peripheral blood lymphocytes was assayed in all available members of three families in which cases of X-linked ichthyosis were frequently seen. Lymphocytes from all the patients with this disease lacked steroid sulphatase activity and some female members who were probably heterozygotes, showed significantly lower enzyme activity compared with other healthy family members and normal controls. This suggest that females heterozygous for X-linked ichthyosis in these families could be traced enzymatically. Three childless females in these families were found to be possible heterozygotes in view of their lower enzyme levels. It was found that polyacrylamide gel electrophoretic mobility of serum low-density lipoproteins was increased in X-linked ichthyosis patients but was not changed in the probable heterozygotes. The detection of individuals heterozygous for X-linked ichthyosis, for the purpose of precise genetic counselling, may be possible by measuring steroid sulphatase activity of peripheral blood lymphocytes.

The effect of steroid sulphatase on stratum corneum shedding in patients with X-linked ichthyosis

After the application under occlusion of partially purified stratum corneum steroid sulphatase to the skin of patients with X-linked ichthyosis, the detachment ratio of stratum corneum fragments was significantly increased. There was no significant change in normal subjects or in patients with ichthyosis vulgaris.

Recessive X-linked ichthyosis: lack of immunologically detectable steroid sulfatase enzyme protein

Patients with recessive X-linked ichthyosis (RXLI), one hereditary form of scaly skin, lack activity of the enzyme steroid sulfatase in all tissues studied. To investigate the molecular defect underlying the lack of enzyme activity, we prepared antisera against normal enzyme by injecting normal placental microsomal suspensions or partially purified steroid sulfatase into rabbits. Antibody activity was assessed by immunoprecipitation of detergent solubilized steroid sulfatase. In addition, we prepared rabbit antisera against RXLI placental microsomal suspensions. To detect immunologically cross-reactive material in patients' placentas, extracts were studied by immunoblot techniques and by competition with normal enzyme for antibody binding. Patients' extracts did not contain immunoreactive material co-migrating on electrophoresis with purified enzyme nor did they inhibit immunoprecipitation of normal enzyme. Sera from rabbits immunized with RXLI placental microsomes contain no antibodies to normal steroid sulfatase, as judged by their failure to immunoprecipitate normal enzyme or to react with normal steroid sulfatase on immunoblot. Thus the mutation in RXLI appears to reduce steroid sulfatase enzyme protein as well as enzyme activity.