Cornified cell envelope proteins and keratins are normally distributed in harlequin ichthyosis

Long-term survivors of harlequin ichthyosis (HI) have raised a controversy over the differences between HI and lamellar ichthyosis (LI). Abnormal lamellar granules and the failure of conversion from profilaggrin to filaggrin have been reported in HI. On the other hand, malformation of the cornified cell envelope as a result of mutation of keratinocyte transglutaminase has been found in LI. In the present study, we analyzed the distribution of keratins, filaggrin/profilaggrin and cornified cell envelope proteins in the epidermis in HI. We studied a newborn Japanese male with typical clinical features of HI. Electron microscopic observation of a skin biopsy specimen taken from the trunk revealed the presence of lipid inclusions within the cornified cells, the absence of lamellar granules in the granular layer keratinocytes, and a lack of extracellular lamellar structures between the first cornified cell and the granular cell. Immunohistochemical labeling showed a normal distribution of keratins (keratins 1,5, 10, and 14), filaggrin/profilaggrin and cornified cell envelope proteins (involucrin, small proline-rich proteins, and loricrin) in the epidermis of lesional skin. The present observations of the patient's skin verified that keratins and cornified cell envelope proteins are normally expressed in HI, thus demonstrating a different pathogenesis between HI and LI.     

Altered expression of immunoreactive involucrin in lamellar ichthyosis

In some cases of lamellar ichthyosis, mutations in the epidermal transglutaminase gene and a reduction in the thickness of the cornified envelope have been documented. Involucrin is a major component of the cornified envelope and a substrate for epidermal transglutaminase. The aim of the present work was to analyse the expression of involucrin in lamellar ichthyosis. An ultrastructural study and/or immunohistochemical and biochemical techniques with anti-involucrin antibody were carried out on the epidermis of fifteen patients (12 families) suffering from lamellar ichthyosis. The effect of in vivo retinoid treatment on the involucrin epidermal expression was also investigated. Four cases with normal skin, seventeen cases of other ichthyoses and ten cases of psoriasis were used as controls. In all these cases of lamellar ichthyosis, a thin or absent cornified envelope, electron-dense granules inside corneocytes and a decrease of the epidermal involucrin expression were observed. In the patients receiving treatment with retinoids, western blot and ELISA revealed an increase in the involucrin expression. The decreased expression of involucrin in lamellar ichthyosis could contribute to the altered desquamation process accompanying the disease, since the clinical improvement associated with retinoid treatment is accompanied by an increase in the expression of involucrin.     

Compound heterozygous mutations including a de novo missense mutation in ABCA12 led to a case of harlequin ichthyosis with moderate clinical severity

Harlequin ichthyosis (HI) is one of the most devastating genodermatoses. Recently, ABCA12 mutations were identified as the cause of HI. A newborn Japanese male demonstrated the typical features of HI. The patient was treated with oral etretinate and his general condition has been good (now aged 1.5 years). This patient with moderate clinical severity was compound heterozygous for a novel de novo missense mutation 1160G > A (S387N) in exon 10 and a maternal deletion mutation 4158_4160delTAC (T1387del) in exon 28 of ABCA12. T1387del was a deletion of a highly conserved threonine residue within the first adenosine 5' triphosphate-binding domain and is thought to seriously affect the function of the ABCA12 protein. Conversely, the residue 387 is located outside the known active sites of ABCA12 and S387N is predicted not to lead to a serious functional deficiency in ABCA12. Electron microscopy revealed abnormal lamellar granules in the granular layer cells and a moderate number of lipid vacuoles in the cornified cells. Disturbed glucosylceramide transport was confirmed in the cultured keratinocytes from the patient. No de novo mutation in ABCA12 has yet been reported either in HI or lamellar ichthyosis. The present case suggested that a de novo ABCA12 mutation might underlie HI.     

Autosomal-dominant lamellar ichthyosis: Ultrastructural characteristics of a new type of congenital ichthyosis

Summary Recently, autosomal-dominant lamellar ichthyosis (ADLI) has been shown to be a new genetic trait with clinical and histologic features similar to those of autosomal-recessive lamellar ichthyosis. In two patients affected with ADLI, the malpighian keratinocytes showed ultrastructural signs of increased cellular metabolism. The tonofilaments and keratohyaline granules were regular in structure and number. However, as a distinctive ultrastructural feature, a prominent transforming zone was found between the granular and horny layers. Moreover, a normal keratin pattern and only a limited number of lipid inclusions were observed in the stratum corneum. Thus, ADLI can be distinguished from the autosomal-recessive forms of lamellar ichthyosis, permitting a correct diagnosis when genetic counselling has to be given in sporadic cases.     

四种遗传性鱼鳞病临床表型和组织病理的比较研究

目的：比较四种鱼鳞病（寻常型鱼鳞病；X-连锁鱼鳞病；板层状鱼鳞病；大疱性鱼鳞病）临床表型和组织病理的差异。方法：对鱼鳞病患者进行临床表型分析、皮损组织病理和电镜检测。结果：1．寻常型鱼鳞病：浅褐色多角形鳞屑，组织病理角化过度伴局灶性角化不全，颗粒层变薄；电镜示透明角质颗粒数量减少且结构异常。2．X-连锁鱼鳞病：粗大深褐色鳞屑，组织病理中度角化过度，颗粒层正常或稍增厚。3．板层状鱼鳞病：粗大黑色板样鳞屑，组织病理致密板层状角化过度伴灶性角化不全，局灶颗粒层增厚，棘层不规则增生肥厚；电镜示角质包膜异常。4．大疱性鱼鳞病：棕色疣状鳞屑，组织病理致密角化过度，颗粒层显著增厚，颗粒层及棘层中上部细胞核周空泡改变。电镜可见异常角蛋白分布于基底层以上全部表皮，棘细胞松解，颗粒层细胞核周围有异常聚集的角蛋白丝。结论：四种鱼鳞病患者临床表型、组织病理和严重程度有明显差异。     

Oral treatment of ichthyosis with an aromatic retinoid

An aromatic retinoid (Ro-10/9359) was used for oral treatment of five cases of ichthyosis (three lamellar, two X-linked). Complete clearing of the skin lesions was achieved in all five patients within 24.2±3.2 days (X-linked 21.75±6.5, lamellar 23 days). Histopathology showed reduction of the hyperkeratosis, and thickening of the granular layer. Clinical side effects were of mild intensity and included cheilitis, conjunctivitis and pruritus. All side effects were reversible upon reduction of the daily dosage. In three patients treatment was discontinued after clearing of lesions. Fresh lesions re-appeared 6 weeks later. One patient with X-linked ichthyosis developed two recurrences during maintenance treatment; one patient with lamellar ichthyosis was kept in complete remission for 9 weeks on a reduced daily dosage.     

Collodion baby and lamellar ichthyosis

It is important to differentiate the collodion baby from harlequin ichthyosis as the latter rarely survives past the first few days of life. Occasionally, babies share features of both disorders and defy a clinical diagnosis. We recently encountered such a baby who initially presented with harlequin-like features, but evolved into lamellar ichthyosis once the keratin cast was shed. Since the routine histology of all these ichthyoses is similar, we used electron microscopy to study serial biopsy specimens from the affected infant on days 7, 14, and 150, and compared them to our own other cases of harlequin ichthyosis and lamellar ichthyosis. Electron microscopic studies of our case revealed that the marginal band of cornified cells of the stratum corneum was absent when the baby exhibited collodion/harlequin ichthyosis features. Another biopsy taken when the clinical picture evolved into lamellar-like ichthyosis, showed a well-formed marginal band in the cornified cells. In harlequin ichthyosis, the marginal band is present at birth. It is suggested that electron microscopy can differentiate severe collodion baby from harlequin ichthyosis at birth using the absence of the marginal band. Previously reported features of harlequin ichthyosis, such as the presence of giant mitochondria and an abnormal formation of the marginal band in luminal villi of acrosyringeal eccrine duct, were absent in our case.     

Rheumatologic effects of etretinate

The effects of chronic hypervitaminosis A and long-term isotretinoin treatment on bone include cortical hyperostosis, ligament calcification and premature epiphyseal closure. Similar effects have now been reported in patients under maintenance treatment with etretinate in high doses. Etretinate, an oral, aromatic, synthetic vitamin A derivative, is widely used in Europe for disorders of keratinization. We report the cases of two patients--one with lamellar ichthyosis, the other with pachyonychia congenita--who developed such bone diseases during treatment with etretinate over 2 and 6 years respectively. The doses ranged from 0.5 to 1 mg/kg/day. Two years after starting treatment (total dose 25 g), the patient with lamellar ichthyosis complained of mechanical pain in the lumbar region and hips. Radiography showed calcification of the extraspinal tendons and ligaments and hyperostosis of the calcaneus bone at the insertion of the plantar ligament. After six years of etretinate treatment (total dose 50 g), the patient with pachyonychia congenita presented with scoliosis and limb length discrepancy. The musculoskeletal abnormalities resembled chronic hypervitaminosis A, with such osseous changes as demineralization, thinning and increased curvature of long bones with osteopenia, and premature closure of the epiphyses. Acroosteolysis was also present. Etretinate has been implicated in the formation of spinal hyperostoses and calcification of extraspinal ligaments in patients who had taken the drug for many years. The occurrence of premature epiphyseal closure in children certainly is a consequence of therapy with relatively high doses of etretinate for six years. But premature epiphyseal closure may also result from trauma to a fragile bone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ichthyosis with laminated membrane structures

Clinical, light-microscopic, and electron-microscopic features of a new type of ichthyosis are presented. The ichthyotic disease of a 75-year-old woman appeared in early childhood as dry and scaly skin. It slowly progressed to thickened and folded hyperkeratosis on her neck and axillae. The skin on the other parts of her body was shiny, red and hard. Her physical development was normal. Light microscopy showed acanthosis and papillomatosis with hyperkeratosis. The granular cells were vacuolated. Electron microscopy revealed diagnostic changes, i.e., concentric or parallel lamellar membrane structures and amorphous material in upper epidermal cells. Corresponding lamellar material was also seen in the cornified cells. The keratinosomes were abnormal and a hypothesis is presented indicating that a defect in keratinosome formation results in vacuolization and abnormal desquamation in this disease. According to the current classification, the present type of ichthyosis is one subgroup of lamellar ichthyosis. We have called it ichthyosis with laminated membrane structures, because they are electron-microscopically diagnostic. The mode of inheritance is unknown.     

Abnormal lamellar granules in harlequin ichthyosis.

Lamellar granules are specialized lipid-rich organelles present in epidermal granular cells. They fuse with the apical cell surface and discharge their contents into the intercellular space forming lamellar sheets. It was previously shown by electron microscopy that lamellar granules in biopsies of infants affected with harlequin ichthyosis are either absent or abnormal and no intercellular lamellae could be detected. A monoclonal antibody (AE17) directed against a protein component of lamellar granules was used for immunoblotting and immunohistochemical studies as an indication of both the presence and function of lamellar granules. Epidermal extracts from all harlequin and normal specimens tested showed an immunoreactive protein of 25-28 kD. Immunohistochemical staining of normal skin using AE17 showed apical cytoplasmic staining in the granular layer and intercellular staining between the granular and stratum corneum cells. Harlequin samples showed variable degrees of staining ranging from little to heavy apical cytoplasmic staining of granular cells. No intercellular staining was detected. The immunohistochemical staining pattern correlated with the electron microscopic localization of abnormal vesicles and the absence of intercellular lamellae in the affected samples. We conclude that the vesicles represent lamellar granules that contain the AE17 antigen but are structurally abnormal and defective in their ability to discharge both their lipid and protein contents into the intercellular space. We suggest that this defect in the lamellar granules represents the underlying basis for stratum corneum cell retention and subsequent accumulation of scale in harlequin ichthyosis.     

A serious side-effect of etretinate (Tigason®)

A 19-year-old patient with lamellar ichthyosis is described. She received etretinate during 5 consecutive years. A serious ossification abnormality of both forearms prompted arrest of etretinate treatment.     

Squamous cell carcinoma arising from lesions of porokeratosis palmaris et plantaris disseminata

We report a 63-year-old Japanese man with numerous hyperkeratotic papules of porokeratosis palmaris et plantaris disseminata (PPPD) who developed multiple squamous cell carcinomas on the lesional sites of the palms and soles. The hyperkeratotic papules, which showed tightly packed columns of parakeratotic cells in the cornified layer (cornoid lamella), lost granular layer, and dyskeratotic keratinocytes in the epidermis below the cornoid lamella histologically, had been noticed on the palms and soles from the age of 28 and 43, respectively. He has no family history of such hyperkeratotic papules. Treatment with etretinate (10-50 mg/day) was given discontinuously, and the total dose of etretinate amounted to approximately 21 g over 14 years (average: 0.07 mg/kg/day). He noticed erosions on the hyperkeratotic papules on the left sole and palm more than 9 months after cessation of treatment with etretinate. Histological findings showed numerous atypical keratinocytes in the epidermis and upper dermis with mononuclear cell infiltration seen in the upper dermis. The diagnosis of squamous cell carcinoma arising from the lesions of porokeratosis palmaris et plantaris was made. Five erosions with histologically malignant changes were removed 1 cm from the margin of the erosions. These findings suggest that etretinate may have an inhibitory action on malignant changes in PPPD.     

Analyses of the transglutaminase 1 gene mutation and ultrastructural characteristics in a Japanese patient with lamellar ichthyosis

We described a Japanese female with lamellar ichthyosis whose transglutaminase 1 gene (TGM1 gene) was mutated. DNA sequence analysis revealed that the patient had a homozygous mutation, i.e. a point mutation from G to A at nucleotide 1494 resulting in the substitution of glycine for arginine at codon 143. Her mother was heterozygous for this mutation. In situ transglutaminase assay in the patient's skin showed loss of enzyme activity. Ultrastructural examination revealed incomplete formation of cornified cell envelopes and electron-dense materials adjacent to plasma membranes. These results suggest that defective transglutaminase activity caused by homozygous TGM1 gene mutation (G143R) results in disruption of cornified envelope assembly and the clinical phenotype of lamellar ichthyosis.     

Cellular kinetics in nonbullous ichthyosiforme erythroderma

An in vitro double labeling technique with 3H-Tdr has been used to study the cell renewal in three cases of lamellar ichthyosis. Each case was characterized by a rapid rate of cell proliferation as it occurs in psoriasis. But, in contrast to psoriasis, lamellar ichthyosis has no increased proportion of germinative cells and exhibits prominent granular layer. Horny layer at light microscopy is mainly orthokeratotic. This indicates that increased mitotic activity alone cannot account for the typical acanthosis of psoriasis.     

Psoriasis occurring in lamellar ichthyosis: response to Epilyt

Psoriasis occurring in a patient with lamellar ichthyosis is reported. Similar self-limited episodes had occurred earlier. On histopathologic examination of a biopsy specimen, an eruptive plaque showed parakeratosis and a reduction in the granular layer. Electrophoretic analysis of the keratins isolated from the epidermis of a plaque showed a reduction in the amount of the 67 kd polypeptide compared to the keratins of ichthyosis epidermis. Both of these findings support the diagnosis of psoriasis. Epilyt, applied daily, was effective in removing scales.     

Pathogenesis of the permeability barrier abnormality in epidermolytic hyperkeratosis

Epidermolytic hyperkeratosis is a dominantly inherited ichthyosis, frequently associated with mutations in keratin 1 or 10 that result in disruption of the keratin filament cytoskeleton leading to keratinocyte fragility. In addition to blistering and a severe disorder of cornification, patients typically display an abnormality in permeability barrier function. The nature and pathogenesis of the barrier abnormality in epidermolytic hyperkeratosis are unknown, however. We assessed here, first, baseline transepidermal water loss and barrier recovery kinetics in patients with epidermolytic hyperkeratosis. Whereas baseline transepidermal water loss rates were elevated by approximately 3-fold, recovery rates were faster in epidermolytic hyperkeratosis than in age-matched controls. Electron microscopy showed no defect in either the cornified envelope or the adjacent cornified-bound lipid envelope, i.e., a corneocyte scaffold abnormality does not explain the barrier abnormality. Using the water-soluble tracer, colloidal lanthanum, there was no evidence of tracer accumulation in corneocytes, despite the fragility of nucleated keratinocytes. Instead, tracer, which was excluded in normal skin, moved through the extracellular stratum corneum domains. Increasing intercellular permeability correlated with decreased quantities and defective organization of extracellular lamellar bilayers. The decreased lamellar material, in turn, could be attributed to incompletely secreted lamellar bodies within granular cells, demonstrable not only by several morphologic findings, but also by decreased delivery of a lamellar body content marker, acid lipase, to the stratum corneum interstices. Yet, after acute barrier disruption a rapid release of preformed lamellar body contents was observed together with increased organelle contents in the extracellular spaces, accounting for the accelerated recovery kinetics in epidermolytic hyperkeratosis. Accelerated recovery, in turn, correlated with a restoration in calcium in outer stratum granulosum cells in epidermolytic hyperkeratosis after barrier disruption. Thus, the baseline permeability barrier abnormality in epidermolytic hyperkeratosis can be attributed to abnormal lamellar body secretion, rather than to corneocyte fragility or an abnormal cornified envelope/cornified-bound lipid envelope scaffold, a defect that can be overcome by external applications of stimuli for barrier repair.     

Epidermal transglutaminase in the ichthyoses.

Membrane-bound transglutaminase (TGm) is responsible for the cross-linking of proteins to form the cornified envelope. Since abnormalities have been reported in the envelope in certain ichthyoses, we have carried out a survey of TGm concentrations in scales from these disorders. Surprisingly, a striking and specific increase in enzyme activity was found in patients with non-erythrodermic autosomal recessive lamellar ichthyosis. It is not clear how this increase is related to the underlying recessive mutation.     

The Keratinization Disorder in Collodion Babies Evolving into Lamellar Ichthyosis*

Two collodion baby girls with disorder evolving into lamellar ichthyosis were followed by light and electron microscopy. Light microscopically, the neonatal collodion skin was characterized by a thick compact stratum corneum which was PAS positive in its upper two thirds, by a thin stratum granulosum and by a non-acanthotic stratum spinosum with normal mitotic activity. Electron microscopically, the upper stratum corneum appeared pathological, whereas the lower part was normal except for some minor parakeratosis. The main alterations in the underlying stratum granulosum were diminished tonofibrils and keratohyalin. Biopsy specimens taken at the age of 2 weeks were typical for lamellar ichthyosis and showed hyperkeratosis with focal parakeratosis, a thickened stratum granulosum in which the cellular content of keratohyalin and tonofibrils was moderately diminished, and acanthosis with increased mitotic activity. It appears that the ultrastructural changes of the stratum granulosum, seen in lamellar ichthyosis, are already present in the collodion skin of the newborn, at a time when the epidermis does not yet show an increase in mitotic activity.     

Localization of sphingomyelin during the development of dorsal and tail epidermis of mice

BACKGROUND: The water permeability barrier of the stratum corneum seems to be regulated primarily by lamellar bodies situated between the corneocytes; the lamellar bodies originate largely from polar lipid precursors, mainly sphingomyelin (SM), provided by the cells of the stratum granulosum via exocytosis of their lamellar body content. OBJECTIVES: The aim of our study was to evaluate the cellular distribution of SM during development of the epidermis. Methods In this study, we investigated the expression and localization of SM in both adult and fetal mouse skin by a cytochemical detection method, immunofluorescence microscopy and immunoelectron microscopy, using anti-SM antibody, a specific binding protein to SM (lysenin), and Nile red stain. In addition, we measured transepidermal water loss to estimate the barrier function of the fetal skin. RESULTS: We observed that SM was widely distributed from the basal layer to the granular layer in the adult mouse epidermis. An intense cytochemical reaction for SM was observed on embryonic day E14.5 of gestation just before the differentiation of the granular and squamous cells from the intermediate cells. The immunofluorescence indicating SM was detected in two regions, i.e. the most superficial zone of the granular layer and the upper spinous layer after the cell differentiation at the late gestational age. This distribution was not detected by conventional lipid staining, such as with Nile red stain. Immunoelectron microscopy revealed that SM was mainly localized in the intercellular spaces of the adult mouse epidermis and in the intracellular vesicles without a complete lamellar structure in the cytoplasm of epidermal cells of E14.5 fetuses. It is well known that the formation of the structurally mature cornified cell envelope occurs at E15.5 of development. The skin of fetuses at E16.5 showed a definite barrier function. CONCLUSIONS: These findings suggest that SM dynamics is related to the formation of the lipid envelope, cell differentiation, and epidermal barrier function during development.     

Lamellar ichthyosis: response to etretinate with transglutaminase 1 recovery

We studied a case of typical lamellar ichthyosis before and after etretinate treatment for the expression of transglutaminase 1 (TGK) and the presence or absence of the marginal band. Before the treatment, TGK was undetectable, although two other components of the marginal band, loricrin and involucrin, were detected by immunostaining in a normal pattern. The marginal band of the corneocytes was either thin and irregular or completely absent by electron microscopic study. After therapy with etretinate, 50 mg/day, the patient' s skin improved, and biopsies were taken at 4 and 8 months. Transglutaminase 1 became detectable by immunostaining. The marginal band was still absent in most corneocytes.