Adhesion molecules and related proteins in Darier's disease and Hailey-Hailey disease

A fluorescence imaging technique suggests that sweat leakage in the epidermis contributes to the pathomechanism of palmoplantar pustulosis

Sweat is an essential protection system for the body, but its failure can result in pathologic conditions, including several skin diseases, such as palmoplantar pustulosis (PPP). As reduced intraepidermal E-cadherin expression in skin lesions was confirmed in PPP skin lesions, a role for interleukin (IL)-1-rich sweat in PPP has been proposed, and IL-1 has been implicated in the altered E-cadherin expression observed in both cultured keratinocytes and mice epidermis. For further investigation, live imaging of sweat perspiration on a mouse toe-pad under two-photon excitation microscopy was performed using a novel fluorescent dye cocktail (which we named JSAC). Finally, intraepidermal vesicle formation which is the main cause of PPP pathogenesis was successfully induced using our "LASER-snipe" technique with JSAC. "LASER-snipe" is a type of laser ablation technique that uses two-photon absorption of fluorescent material to destroy a few acrosyringium cells at a pinpoint location in three-dimensional space of living tissue to cause eccrine sweat leakage. These observatory techniques and this mouse model may be useful not only in live imaging for physiological phenomena in vivo such as PPP pathomechanism investigation, but also for the field of functional physiological morphology.

Inherited desmosomal disorders

Desmosomes serve as intercellular junctions in various tissues including the skin and the heart where they play a crucial role in cell-cell adhesion, signalling and differentiation. The desmosomes connect the cell surface to the keratin cytoskeleton and are composed of a transmembranal part consisting mainly of desmosomal cadherins, armadillo proteins and desmoplakin, which form the intracytoplasmic desmosomal plaque. Desmosomal genodermatoses are caused by mutations in genes encoding the various desmosomal components. They are characterized by skin, hair and cardiac manifestations occurring in diverse combinations. Their classification into a separate and distinct clinical group not only recognizes their common pathogenesis and facilitates their diagnosis but might also in the future form the basis for the design of novel and targeted therapies for these occasionally life-threatening diseases.

[Early guttate leukoderma in Darier's disease in a patient with black skin]

BACKGROUND

The clinical manifestations of Darier's disease are polymorphic and diverse. Guttate leukoderma has been described in around twenty patients with genetically pigmented skin. We report a case of widespread guttate leukoderma several years before the classic signs of Darier's disease in a patient with black skin.

CASE REPORT

A 19-year-old woman consulted for characteristic signs of Darier's disease evolving for the previous four years. Examination revealed perifollicular, non-confluent hypopigmented macules and papules in small drop size (1-5mm in diameter) scattered on the trunk, limbs and the jaw and chin. These hypopigmented lesions had been present since the age of six years. Histology of the keratotic papules confirmed the diagnosis of Darier's disease. Histological inspection of a hypopigmented lesion showed hyperkeratosis, acantholysis and a considerable reduction of epidermal melanin pigment.

DISCUSSION

Our observation suggests that a guttate leukoderma could be an early sign, readily accessible to dermatologists, in the diagnosis of Darier's disease in black-skinned patients.

Secretory pathway stress responses as possible mechanisms of disease involving Golgi Ca2+ pump dysfunction

In mammalian tissues, uptake of Ca(2+) and Mn(2+) by Golgi membranes is mediated by the secretory pathway Ca(2+) -ATPases, SPCA1 and SPCA2, encoded by the ATP2C1 and ATP2C2 genes. Loss of one copy of the ATP2C1 gene, which causes SPCA1 haploinsufficiency, leads to squamous cell tumors of keratinized epithelia in mice and to Hailey-Hailey disease, an acantholytic skin disease, in humans. Although the disease phenotypes resulting from SPCA1 haploinsufficiency in mice and humans are quite different, each species-specific phenotype is remarkably similar to those arising as a result of null mutations in one copy of the ATP2A2 gene, encoding SERCA2, the endoplasmic reticulum (ER) Ca(2+) pump. SERCA2 haploinsufficiency, like SPCA1 haploinsufficiency, causes squamous cell tumors in mice and Darier's disease, also an acantholytic skin disease, in humans. The phenotypic similarities between SPCA1 and SERCA2 haploinsufficiency in the two species, and the general functions of the two pumps in consecutive compartments of the secretory pathway, suggest that the underlying disease mechanisms are similar. In this review, we discuss evidence supporting the view that chronic Golgi stress and/or ER stress resulting from Ca(2+) pump haploinsufficiencies leads to activation of cellular stress responses in keratinocytes, with the predominance of proapoptotic pathways (although not necessarily apoptosis itself) leading to acantholytic skin disease in humans and the predominance of prosurvival pathways leading to tumors in mice.

[Segmental Darier disease : treatment with pulsed dye laser]

Darier disease is often associated with pruritus and an unpleasant odor, causing medical and emotional problems. Ablative laser therapy has proven effective in ameliorating these symptoms. Side effects of this approach include permanent hypopigmentation and a risk of scarring. We present two cases where non-ablative therapy with pulsed dye lasers proved a safe and effective way to manage the intertriginous lesions. Although the mechanism of action is unclear, our success indicates that pulsed dye laser therapy is an option in Darier disease. Larger numbers of patients, ideally in multicenter studies, must be treated in this way to confirm our results.

ADAM10-mediated E-cadherin release is regulated by proinflammatory cytokines and modulates keratinocyte cohesion in eczematous dermatitis

Acute eczema is an inflammatory skin disease characterized by the formation of small intraepidermal blisters, reduction of the adhesion molecule E-cadherin from the keratinocyte surface, and impaired keratinocyte cohesion. Here, we reveal that the disintegrin and metalloprotease ADAM10 is critically involved in regulating E-cadherin cell-surface expression in cultured primary human keratinocytes and in diseased human skin. Proinflammatory cytokines, transforming growth factor-beta, and lipopolysaccharide led to increased release of soluble E-cadherin by activating mitogen-activated protein kinase signaling in cultured keratinocytes. Moreover, these stimuli decreased the amount of pro-ADAM10 and increased the level of the active protease, leading to loss of E-cadherin from the cell surface and decreased keratinocyte cohesion. In situ examination and immunoblot analyses of E-cadherin and ADAM10 expression in lesional skin of eczema revealed that the reduction of E-cadherin expression in areas of blister formation closely correlated with increased level of ADAM10 expression and elevated E-cadherin shedding. Our data suggest that ADAM10-mediated E-cadherin proteolysis leads to the impaired cohesion of keratinocytes observed in eczematous dermatitis and provide previously unreported insights into the understanding of the molecular mechanisms involved in inflammatory diseases with loss in epithelial integrity.

Lithium suppresses epidermal SERCA2 and PMR1 levels in the rat

Autosomal dominant mutations in the genes encoding the calcium ATPases SERCA2 and PMRI/SPCA1 cause the genodermatoses Darier disease (DD) and Hailey-Hailey disease (HHD), respectively. Recent observations indicated that the level of the pathogenic proteins greatly decreases in the affected areas of the epidermis in these disorders. Here we addressed how lithium, a recognized exacerbating factor in Darier disease, affects the epidermal expression of SERCA2 and PMR1/SPCA1 in the rat as a model. Standard histologic and immunohistochemical methods were utilized in 3 lithium-treated and 3 control animals. A significant suppression of epidermal SERCA2 and PMR1 levels were observed as a result of lithium therapy in addition to marked qualitative and quantitative changes in the stratum corneum and the granular layer of the epidermis in the treated animals. Our findings suggest that exacerbating factors in calcium ATPase disorders of the skin suppress epidermal SERCA2 and PMR1 levels, further decreasing the already haploinsufficient protein expression to a potentially critical level in Darier disease and Hailey-Hailey disease, respectively. Lithium therapy should specifically be avoided not only in Darier disease, but Hailey-Hailey disease as well.

Autosomal-dominant calcium ATPase disorders

Darier disease (DD) and Hailey-Hailey disease (HHD) are the only known autosomal-dominant Ca2+ ATPase disorders. Epidermal symptoms selectively occur in the affected individuals, the precise reason for which is still not fully understood. Here, we review the clinical, epidermal, and molecular features of the two genodermatoses. It is concluded that epidermal Ca2+ regulation disturbances and epigenetic factors may play an even more prominent role in the pathogenesis of DD and HHD than earlier appreciated.

Consequences of depleted SERCA2-gated calcium stores in the skin

Sarco(endo)plasmic reticulum Ca2+-ATPase isoform 2 (SERCA2) pumps belong to the family of Ca2+-ATPases responsible for the maintenance of calcium in the endoplasmic reticulum. In epidermal keratinocytes, SERCA2-controlled calcium stores are involved in cell cycle exit and onset of terminal differentiation. Hence, their dysfunction was thought to provoke impaired keratinocyte cohesion and hampered terminal differentiation. Here, we assessed cultured keratinocytes and skin biopsies from a canine family with an inherited skin blistering disorder. Cells from lesional and phenotypically normal areas of one of these dogs revealed affected calcium homeostasis due to depleted SERCA2-gated stores. In phenotypically normal patient cells, this defect compromised upregulation of p21(WAF1) and delayed the exit from the cell cycle. Despite this abnormality it failed to impede the terminal differentiation process in the long term but instead coincided with enhanced apoptosis and appearance of chronic wounds, suggestive of secondary mutations. Collectively, these findings provide the first survey on phenotypic consequences of depleted SERCA-gated stores for epidermal homeostasis that explain how depleted SERCA2 calcium stores provoke focal lesions rather than generalized dermatoses, a phenotype highly reminiscent of the human genodermatosis Darier disease.

Impaired trafficking of the desmoplakins in cultured Darier's disease keratinocytes

Darier's disease is an autosomal dominantly inherited skin disorder characterized by loss of adhesion between epidermal cells, breakdown of desmosome-keratin filaments, and abnormal keratinization. ATP2A2 has been identified as the causative gene of Darier's disease. This gene encodes the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) isoform 2 pump, which transports Ca2+ from the cytosol into the endoplasmic reticulum lumen to maintain a low cytosolic Ca2+ concentration. Using indirect immunofluorescence and biochemical analysis, we investigated the distribution of key desmosomal proteins in normal human and Darier's disease keratinocytes under various calcium conditions. We show that inhibition of SERCA by thapsigargin in normal human keratinocytes impairs the trafficking of the desmoplakins, desmoglein, and desmocollin to the cell surface; these proteins show a diffuse cytoplasmic distribution and, together with plakoglobin, form detergent-insoluble aggregates. In Darier's disease keratinocytes, only the trafficking of desmoplakin is significantly inhibited; in these cells, desmoplakin forms insoluble aggregates when extracted with mild detergent. In contrast, the transmembrane proteins desmoglein and desmocollin are efficiently transported to the cell surface. These proteins, along with plakoglobin, remain equally distributed between detergent-soluble and -insoluble fractions. We also demonstrate an interaction between SERCA2 and desmoplakin during differentiation. Our results provide further insights into the critical role of calcium ATPases in maintaining epidermal integrity.

E-cadherin controls adherens junctions in the epidermis and the renewal of hair follicles

E-cadherin is thought to mediate intercellular adhesion in the mammalian epidermis and in hair follicles as the adhesive component of adherens junctions. We have tested this role of E-cadherin directly by conditional gene ablation in the mouse. We show that postnatal loss of E-cadherin in keratinocytes leads to a loss of adherens junctions and altered epidermal differentiation without accompanying signs of inflammation. Overall tissue integrity and desmosomal structures were maintained, but skin hair follicles were progressively lost. Tumors were not observed and beta-catenin levels were not strongly altered in the mutant skin. We conclude that E-cadherin is required for maintaining the adhesive properties of adherens junctions in keratinocytes and proper skin differentiation. Furthermore, continuous hair follicle cycling is dependent on E-cadherin.

Upregulation of P-cadherin expression in the lesional skin of pemphigus, Hailey-Hailey disease and Darier's disease

BACKGROUND

Autoimmune blistering diseases, pemphigus vulgaris (PV) and pemphigus foliaceus (PF), are known to be caused by binding of autoantibodies to the desmosomal cadherins, desmoglein 3 and desmoglein 1, respectively. Recently, mutations in the genes coding Ca2+ pumps leads to inherited blistering diseases, Hailey-Hailey disease (HHD) and Darier's disease (DD). Cadherins are a family of Ca2+-dependent cell adhesion molecules and P-cadherin is one of the major cadherins expressed in the epidermis. Although detailed mechanisms of acantholysis of these blistering diseases have not been fully clarified, abnormal expression of cadherins caused by altered Ca2+ concentration due to the binding of autoantibodies to cell surface or by mutations in Ca2+ pumps is suggested to be involved in mechanisms of acantholysis of these autoimmune and inherited blistering diseases. The purpose of the present study was to determine whether altered P-cadherin expression is present in these diseases.

METHOD

Distribution patterns of P-cadherin in skin specimens from patients with PV (n=2), PF (n=2), HHD (n=4) and DD (n=3), were examined with confocal laser scanning microscopy using two anti-P-cadherin antibodies, 6A9 and NCC-CAD-299.

RESULTS

In normal control skin, P-cadherin expression was restricted to the basal layer. In contrast, positive immunostaining of P-cadherin was observed not only in the basal cells, but also in the suprabasal cells in lesional skin of all the acantholytic diseases.

CONCLUSIONS

The present results clearly demonstrated that upregulation of P-cadherin expression occurs in the acantholysis in all the four blistering diseases PV, PF, HHD and DD. Upregulation of P-cadherin may be involved in the pathomechanism of both the autoimmune blistering diseases and the inherited blistering diseases.

Dissociation of intra- and extracellular domains of desmosomal cadherins and E-cadherin in Hailey-Hailey disease and Darier's disease

In order to clarify the pathomechanism of acantholysis in Hailey-Hailey disease (HHD) and Darier's disease (DD), the distribution of desmosomal and adherens junction-associated proteins was studied in the skin of patients with HHD (n = 4) and DD (n = 3). Domain-specific antibodies were used to determine the cellular localization of the desmosomal transmembrane glycoproteins (desmogleins 1 and 3 and desmocollin), desmosomal plaque proteins (desmoplakin, plakophilin and plakoglobin) and adherens junction-associated proteins (E-cadherin, alpha-catenin, beta-catenin and actin). A significant difference in staining patterns between intra- and extracellular domains of desmosomal cadherins and E-cadherin was demonstrated in acantholytic cells in both HHD and DD, but not in those in pemphigus vulgaris and pemphigus foliaceus samples used as controls. In acantholytic cells in HHD and DD, antibodies against attachment plaque proteins and intracellular epitopes of desmosomal cadherins exhibited diffuse cytoplasmic staining, whereas markedly reduced staining was observed with antibodies against extracellular epitopes of the desmogleins. Similarly, membrane staining of an intracellular epitope of E-cadherin was preserved, while immunoreactivity of an extracellular epitope of E-cadherin was destroyed. While the DD gene has been identified as ATP2A2, the gene for HHD has not been clarified. The dissociation of intra- and extracellular domains of desmosomal cadherin and E-cadherin is characteristic of the acantholytic cells in HHD and DD, and not of pemphigus. This common phenomenon in HHD and DD might be closely related to the pathophysiological mechanisms in both conditions.

Implication of tissue transglutaminase and desmoplakin in cell adhesion mechanism in human epidermis

The distribution patterns of both tissue and keratinocyte transglutaminases (TGase), as well as that of desmoplakin (DP), have been immunohistochemically investigated in human skin cultured in the absence or presence of cystamine and enalapril, two acantholytic agents. In the control samples, tissue TGase is predominantly expressed in lower layers of the epidermis and is located intercellularly. Conversely, in tissues cultured with cystamine or enalapril, a diffuse cytoplasmatic staining was observed. Similarly, DP, detected on the cell membrane in the control, shifts into the cytosol of the keratinocytes following treatment. The distribution pattern of the keratinocyte enzyme in the acantholytic epidermis was identical to that observed in the normal one. Since cystamine and enalapril are TGase inhibitors and DP was shown to act as a TGase substrate in vitro, we suggest that DP and tissue enzyme may participate in cell adhesion at the intraepidermal level.

Internalization of gap junctions in benign familial pemphigus (Hailey-Hailey disease) and keratosis follicularis (Darier's disease)

Hereditary skin disorders involving acantholysis, such as Hailey-Hailey disease and Darier's disease, have been genetically linked to distinct chromosomal parts which do not code for known structural proteins. Such evidence suggests that the genomic abnormalities underlying these dermatoses may concern functional/regulatory mechanisms of keratinocyte cohesion. Epidermal communication junctions (gap junctions) are responsible for direct coupling of cells and, thus, co-ordinate the behaviour of keratinocytes within the tissue. Consequently, they remain one of the potential, and poorly studied, elements in the pathogenesis of hereditary acantholytic diseases. We have investigated the distribution and fate of gap junctions during non-immune acantholysis, using fine immunolocalization methods at the light and electron microscopic levels. Our results demonstrate normal expression of epidermal gap junction proteins, connexins 26 and 43, in non-lesional skin of Hailey-Hailey and Darier's diseases. The gap junctions were not primarily dismantled during acantholysis, typical of both of the studied dermatoses, but underwent internalization and subsequent cytoplasmic dispersion in the portions of cells which were no longer attached to the rest of the tissue. In Darier's disease, perifollicular acantholysis did not specifically concern epithelium of appendages coexpressing connexin 26 in addition to connexin 43, further indicating that the observed changes in gap junction localization were secondary to the loss of cell-cell contact. We demonstrated that the sequence of changes was identical in both diseases and that the previously described putative differences were apparently related to the degree of acantholysis present in the studied biopsies. The fate of the junctional structures and proteins, documented in the present study, is most probably a form of recycling process also used by normal keratinocytes during organogenesis and tissue differentiation.

1alpha,24-dihydroxyvitamin D3 (tacalcitol) is effective against Hailey-Hailey disease both in vivo and in vitro

We report a case of Hailey-Hailey disease (HHD) in which 1alpha, 24-dihydroxyvitamin D3 (tacalcitol) was effective both clinically (in vivo) and in explant cultures (in vitro) of a skin lesion. The patient was a 65-year-old man with HHD lesions in the axillary and inguinal areas bilaterally. We applied ointment containing 1alpha, 24-dihydroxyvitamin D3 (tacalcitol), an analogue of active vitamin D3, to the lesions and assessed its clinical effectiveness. The HHD lesions in both groins disappeared after treatment with the 1alpha, 24-dihydroxyvitamin D3 ointment, and the remission has continued to the present. A punch biopsy specimen of the lesion that had remitted showed no acantholysis. In addition, dissociation of migrating keratinocytes was observed when biopsy specimens of the HHD skin lesion were cultured in medium without 1alpha,24-dihydroxyvitamin D3, but inhibition of keratinocyte dissociation was observed in medium containing it. These results suggest the effectiveness of 1alpha, 24-dihydroxyvitamin D3 against HHD both in vivo and in vitro.

CD44 variant isoform expression in a variety of skin-associated autoimmune diseases

CD44 variant isoforms are frequently expressed on tissue-infiltrating lymphocytes. By the high incidence of autoimmune reactions of the skin and aiming at new strategies of therapeutic intervention, we became interested in evaluating the CD44 isoform expression profile in autoimmune reactions of the skin. Expression of CD44s, CD44v3, v5, v6, v7, v7-v8, and v10 was evaluated in 55 biopsies of lupus erythematosus, bullous pemphigoid, vasculitis, morphea, and pemphigus vulgaris. Biopsies did not contain CD44v5-, CD44v6-, CD44v7-, or CD44v7-v8-positive leukocytes. Staining with anti-CD44v10 was seen in vasculitis and occasionally in lupus erythematosus, morphea, and bullous pemphigoid. All biopsies contained CD44v3(+) leukocytes, the percentage of CD44v3(+) leukocytes being increased in autoimmune infiltrates with the exception of pemphigus vulgaris. CD44v3 was expressed by CD4(+) cells as well as by part of CD8(+) cells, Langerhans cells, and monocytes. Vascular endothelium also contained CD44v3(+) cells. Only monocytes expressed CD44v10. We assume that CD44v3 and CD44v10 may be targeting leukocytes toward the skin or allow for their retention and expansion via binding of cytokines and chemokines harbored by activated, skin-associated endothelium or provided by cells surrounding the infiltrate. The absence of CD44v6, frequently associated with lymphocyte activation, appears to be a peculiarity of skin-infiltrating leukocytes.

Expression of cadherins and catenins in oral epithelial dysplasia and squamous cell carcinoma

The immunocytochemical expression of cadherins and catenins was examined during the process of oral carcinogenesis by comparing their expression in normal and dysplastic epithelium with primary and metastatic carcinomas. While control epithelium showed normal distribution for P and E cadherin and the catenins, in severe dysplasia P-cadherin was upregulated. In other cases and in carcinoma-in-situ adjacent to infiltrating carcinomas, membranous expression of the cadherins and catenins was reduced or lost. The changes in expression of E-cadherin and the catenins suggest that disruption of the E-cadherin/catenin complex is a late event associated with invasion. In primary carcinomas reduced membranous and cytoplasmic staining were observed for both cadherins and catenins. Abnormal localisation of E-cadherin occurred in the more superficial parts of the better differentiated carcinomas, suggesting abnormality to the E-cadherin complex(es). In contrast, membranous expression of cadherins and catenins was reduced or lost in the deep invasive margin of primary carcinomas and in most poorly differentiated carcinomas. For E-cadherin at least, this reduction appears associated with differentiation, invasion and possibly prognosis. Possible mechanisms involved for changes in expression of the cadherins and associated catenins and areas for further study are discussed.

Ultrastructural localization of cell junctional components (desmoglein, plakoglobin, E-cadherin, and beta-catenin) in Hailey-Hailey disease, Darier's disease, and pemphigus vulgaris

The distribution of desmoglein, plakoglobin, E-cadherin, and beta-catenin in the peri-lesional and lesional skin of Hailey-Hailey disease, Darier's disease, and pemphigus vulgaris was examined by immunoelectron microscopy. In the peri-lesional skin, the immunolabeling of these desmosomal components was localized to desmosomes. Adherens junction-associated E-cadherin and beta-catenin were at the cell periphery, excluding desmosomes. The labeling pattern was similar among these diseases, but the labeling intensity particularly that of plakoglobin in Hailey-Hailey disease and Darier's disease, was less than that of normal controls, suggesting that these glycoproteins are quantitatively less concentrated in the normal epidermis of these inherited diseases. In the acantholytic cells of Hailey-Hailey disease and Darier's disease the immunolabeling of the components of desmosomes was diffusely distributed in the cytoplasms, whereas that of adherensjunction was mostly at the cell periphery and partly diffusely in the cytoplasm. In contrast, desmosomes of detaching keratinocytes in pemphigus vulgaris still showed the labeling of desmoglein and plakoglobin. These findings suggest that the inherited acantholytic diseases, i.e., Hailey-Hailey disease and Darier's disease have a different pathogenesis from that of autoimmune acantholysis in pemphigus vulgaris: The intracellular components of desmosomes may primarily be disrupted in the genetic acantholytic diseases in the initial stages of acantholysis. Several unsolved questions in the previous light microscopic immunofluorescence studies using the same antibodies are now answered: 1) the diffusion of desmosomal proteins is not due to the internalization of desmosomes, 2) intracellular components of adherens junction are also finally dissolved, 3) diffuse cytoplasmic immunofluorescence patterns of desmosomal components could be explained by immunoelectron microscopy as those attached to cell membrane and trapped in tonofilament aggregates.

Hailey-Hailey disease keratinocytes: normal assembly of cell-cell junctions in vitro

The blisters in the inherited disorder, Hailey-Hailey disease, may be caused by defective epidermal junctional complexes. We evaluated these structural complexes in vivo and in vitro. We induced a vesicular lesion in the apparently normal skin of a patient with Hailey-Hailey disease and studied a biopsy of this lesion by transmission electron microscopy. To determine whether acantholysis was related to a defect in the number or assembly of intercellular junctions, we cultured Hailey-Hailey disease keratinocytes in medium containing 0.1 mM Ca2+ and increased the [Ca2+] to 1.1 mM in order to induce assembly of cell-cell junctions. Keratinocytes were examined by double immunofluorescence with antibodies to the desmosome protein, desmoplakin, and the adherens junction protein, vinculin, at intervals after the increase in [Ca2+]. Characteristic Hailey-Hailey disease histopathology was observed by electron microscopy of the patient's skin after trauma, but we found no splitting of desmosomes. Based on the location, intensity, and rate of change of immunofluorescent staining, Hailey-Hailey and normal keratinocytes did not differ in their ability to assemble desmosomes and adherens junctions. Furthermore, we observed no significant morphologic differences between normal and Hailey-Hailey keratinocytes cultured in low and high [Ca2+]-containing media; Hailey-Hailey cells contained abundant normal-appearing desmosomes in 1.1 mM [Ca2+]. Since Hailey-Hailey disease keratinocytes can assemble normal-appearing adherens junctions and desmosomes in vitro, the functional defect may not lie in assembly of cell-cell adhering junctions, or additional perturbation may be required to expose the defect.

Involvement of the adherens junction-actin filament system in acantholytic dyskeratosis of Hailey-Hailey disease. A histological, ultrastructural, and histochemical study of lesional and non-lesional skin

Hailey-Hailey disease is a blistering genodermatosis that shows acantholytic dyskeratosis throughout the epidermis. The aim of our study was to investigate the involvement of adherens structures and cytofilaments in this particular type of acantholysis. Both lesional and non-lesional skin from 18 patients was studied histologically and ultrastructurally. Additionally, the samples were stained for desmosomes, adherens junctions, keratin filaments, actin filaments, and actin-associated proteins, and finally investigated with an electron and a confocal laser scanning microscope (CLSM), respectively. Acantholytic dyskeratosis was not only confined to lesions, but was also focally detectable in clinically unaffected skin. Despite disruption and internalization of the desmosomes, keratinocytes remained linked together by well-preserved adherens junctions. Staining for actin filaments with fluorochrome-labeled phalloidin showed a remarkable formation of actin stress fibers in these keratinocytes. Thus, incomplete acantholysis, as demonstrable in both lesional and non-lesional skin of Hailey-Hailey patients, may be due to a cohesive function of the adherens junction-actin system succeeding the dissolution of desmosomes. Most remarkably, none of the adnexal epithelia expressed the intrinsic defect of cell adhesion. This finding offers an explanation for the successful treatment of Hailey-Hailey disease by dermabrasion, which after complete removal of the involved epidermis results in reepithelialization from skin appendages.

Desmosomal dissolution in Grover's disease, Hailey-Hailey's disease and Darier's disease

Proteins involved in the formation of desmosomes and simpler adherens junctions were studied in three types of non-immune acantholytic diseases; specifically, four cases of Grover's disease (GD), one case of Hailey-Hailey's disease (HHD) and one case of Darier's disease (DD), and these were compared to two cases of immune-mediated acantholytic disease pemphigus vulgaris (PV). The proteins studied included: 1. The intracellular desmosomal proteins, desmoplakin I and II and plakoglobin; 2. The intercellular desmosomal proteins, desmoglein and CD44; and 3. vinculin, which is a major intracellular protein of the simpler aherens junctions. In GD, HHD and DD, immunostaining showed a loss of desmoplakin I and II and plakoglobin from the desmosomes, and a diffuse staining in the cytoplasm. In contrast, in pemphigus vulgaris, these proteins seemed intact and were localized to dot-like spots on the cell surface. Also, desmoglein, and CD44 were slightly affected in GD, and moderately affected in HHD and DD. Absence of desmosomal attachment plaques, the lack of labeling with desmoglein in the affected desmosomes and a diffusion of the labels into cytoplasm were demonstrated with electron microscopy using an immunogold technique. In PV, desmoglein III is one of the target antigens for the autoantibodies in this disease and was only partially preserved in a small number of lesional cells, while CD44 was mostly preserved. Vinculin was intact in GD, HHD and DD, but was lost in PV. This study, our previous work, and that of others, suggest that: 1. In GD, HHD and DD, the proteins of the desmosomal attachment plaque are primarily affected; 2. In PV, the intercellular glycoproteins are primarily involved; and 3. Simple adherens junctions are intact in GD, HHD and DD, but are damaged in PV.

Pseudoangiosarcomatous carcinoma of the genitourinary tract

Two cases of pseudoangiosarcomatous carcinoma of the genitourinary tract, arising in the vulva in one and the bladder in the other, are presented. In case 1, an 84 year old woman, the vulvectomy specimen contained an irregular ulcerated tumour, infiltrating the left labia and extending into the clitoris. In case 2, a 59 year old woman, the excised bladder showed diffuse thickening of its wall by infiltrating haemorrhagic tumour. Both tumours showed focal keratinisation. This, in association with the presence of atypical squamous epithelium, immunohistochemistry and ultrastructural analysis, led to a diagnosis of pseudosarcomatous carcinoma in both cases. Pseudoangiosarcomatous carcinoma should be considered in the differential diagnosis of malignant angiomatoid tumours, particularly those that arise at sites, like the genitourinary tract, where angiosarcoma is rare.

Elevated serum alpha-fetoprotein in a patient with undifferentiated carcinoma of the gall bladder

An uncommon case of undifferentiated carcinoma of the gall bladder in a 65 year old Chinese man, who presented with an increased serum alpha-fetoprotein concentration, is reported. Histologically, the tumour had a primitive appearance and was composed of a pavement-like array of poorly differentiated columnar/polygonal cells. Alpha-fetoprotein was demonstrated in some of the tumour cells using an immunoperoxidase technique. Alpha-fetoprotein secretion in this instance may have occurred because the gall bladder and the liver are of similar embryological origin. Alpha-fetoprotein may also be related to the resurgent expression of oncofetal antigens. This tumour may represent another rare cause of increased serum alpha-fetoprotein concentrations.

Cantharidin-induced acantholysis in Darier's disease: does acantholysis initiate dyskeratosis?

We have examined the action of cantharidin on the skin of patients with Darier's disease, and used immunohistological techniques to determine the distribution of desmosomal components, keratin intermediate filaments, and proteases in cantharidin-induced blisters. Cantharidin induced acantholysis, but the presence of acantholysis did not trigger the development of the characteristic warty, dyskeratotic papules in patients with Darier's disease. The distribution of desmosomal components, keratins and proteases within the acantholytic keratinocytes in the cantharidin-induced blisters was similar to that previously found in acantholytic cells within lesions of Darier's disease: peripheral staining for extracellular desmosomal components was reduced; some desmosomal components were detected diffusely in the acantholytic cells; basal cell keratin markers were expressed by some suprabasal acantholytic cells, and plasminogen was detected in association with acantholytic cells. Cleavage of desmosomes did not reveal the underlying abnormality in Darier's disease.

Immunohistochemical distribution of CD44 and desmoplakin I & II in Hailey-Hailey's disease and Darier's disease

The cell-surface glycoprotein CD44 is found on a wide variety of cells including epidermal cells. It is involved in cell to cell adhesion. Desmoplakin I & II are important components of the attachment plaque of desmosomes. In this study, we compared the distribution patterns of anti-CD44 and anti-desmoplakin I & II in Hailey-Hailey's disease and Darier's disease. In the normal skin, anti-CD44 stained the entire periphery of epidermal keratinocytes while anti-desmoplakin I & II produced dotted staining patterns along the periphery of epidermal keratinocytes. In Hailey-Hailey's disease and Darier's disease, the staining pattern of anti-CD44 on acantholized keratinocytes did not change, but anti-desmoplakin I & II lost their peripheral, dotted patterns and stained diffusely in the cytoplasm in most acantholytic cells. These results suggest that, in Hailey-Hailey's disease and Darier's disease, CD44 may be intact even in acantholytic cells but abnormalities of desmoplakin exist in such cells.

E-cadherin expression in basal cell carcinoma

E-cadherin (E-CD) is a calcium-dependent cell-cell adhesion molecule which is expressed in almost all epithelial tissues. E-CD expression is involved in epidermal morphogenesis and is reduced during tumour progression of mouse epidermal carcinogenesis. It has been suggested that E-CD could play a role as an invasion-suppressor molecule. In the present work we have studied the E-CD expression in 31 patients with basal cell carcinoma (BCC) using an immunohistochemical technique with a monoclonal antibody (HECD-1) specific for human E-CD. E-CD expression was preserved in all specimens of superficial and nodular BCC, and was reduced in 10 of 15 infiltrative BCCs. A heterogeneous distribution of cells with different immunostaining intensity was more frequently observed in specimens of infiltrative BCC. These results suggest that E-CD might be related to the growth pattern and the local aggressive behaviour of BCC, and support the idea that E-CD might play a role as an invasion-suppressor molecule in vivo.