Epidermal Junction Research Articles

A Comparative Study of Direct Immunofluorescence Patterns in Linear IgA Bullous Dermatosis Versus Dermatitis Herpetiformis

Background: Dermatitis herpetiformis (DH) is typically characterized by granular IgA deposition in the papillary dermis on direct immunofluorescence (DIF), and linear IgA bullous dermatosis (LABD) is characterized by linear deposition of IgA along the basement membrane. Other DIF findings in both conditions may include IgG, IgM, and C3 deposition in various patterns. In cases where immunofluorescence findings are unclear, such as continuous but somewhat granular IgA deposition along the dermal–epidermal junction, additional DIF patterns may be helpful in the diagnostic process. Methods: Forty-five cases of digitized images of LABD and 48 digitized images of DH cases were analyzed. The data regarding the positivity and patterns of immunoglobulins were documented and analyzed. Results: None of the LABD cases had a picket fence pattern, while 47.9% (n = 23) of the DH cases had the pattern. Elevated levels of IgG and IgM were found in LABD compared with DH. In DH, higher IgM and kappa light chain levels were observed in the deposited particles compared with those in LABD. Conclusions: The “picket fence pattern” is highly specific for DH (Specificity 100%) but less sensitive (Sensitivity 47.9%). It may be helpful to differentiate between DH and LABD for a more accurate diagnosis.

Concomitant melanoma and keratoma affecting the equine digit: clinical, pathological, and long-term follow-up findings

BackgroundThis case report details a long-term follow-up of a hoof melanoma with dermo-epidermal activity (resembling Spreading Superficial Melanoma (SSM)) in a bay horse with a history of a right front hoof keratoma. Melanomas involving the horse's foot are seldom reported and usually diagnosed as anaplastic melanomas based on signalment and post-mortem examination. The clinical-pathological characteristics of the foot melanoma in this bay horse are consistent with SSM-like described in humans, which is considered an intermediate malignant tumour attending their biological behaviour. However, a definitive diagnosis is limited by the single case and the lack of references in horses.Case presentationA 12-year-old bay Andalusian gelding underwent keratoma removal on the lateral aspect of the hoof wall. A partial resection of the hoof wall was performed for this purpose. Additionally, a plaque-like, hyperkeratotic pigmented lesion, 2 × 2X0,4 cm in size, was observed at the lateral aspect of the coronary band and was also resected for histopathological examination. Microscopically, a melanocytic tumour, characterised by small nests of large polygonal or epithelioid cells infiltrating the basal and suprabasal epidermis, the dermo – epidermal junction, and the superficial dermis, was observed. The neoplastic cells exhibited large euchromatic nuclei, prominent nucleoli, moderate pleomorphism and 4 mitotic figures per 2,37mm2; variable amounts of dark granules (melanin) were present in the cytoplasm, as well as in numerous peritumoral macrophages. The immunophenotype of the tumour cells was PNL2 + + + , S100 + + , AE1/AE3-. A diagnosis of melanoma with dermo-epidermal junction and marked intraepidermal activity (consistent with superficial spreading melanoma) was made.A magnetic resonance imaging (MRI) performed, revealed no further invasion into surrounding structures. Treatment was based on surgical resection and multiple local chemotherapy sessions with cisplatin were applied. The biopsies obtained after treatment showed partial regression of the tumour and different stages of healing. After 26 months of follow-up, there was no signs of malignant spreading into surrounding structures including the pedal bone and distal metastasis but a dark – coloured area persists over the lateral aspect of the coronary band.ConclusionsThis case presents a concomitant keratoma and melanoma with dermo – epidermal activity, resembling a spreading superficial melanoma. After a follow – up of 26 months the horse remains healthy and sound providing new information for clinicians and pathologists. Despite the poor prognosis associated with foot malignant melanocytic tumours, it is important that an early and accurate diagnosis is reached through different diagnostic modalities such as advanced imaging techniques and histopathology. Additionally, these findings demonstrate that the current classification and prognosis for equine foot melanomas are insufficient.

Dihydroavenanthramide D Enhances Skin Barrier Function through Upregulation of Epidermal Tight Junction Expression.

Skin barrier dysfunction and thin epidermis are hallmarks of sensitive skin and contribute to premature aging. Avenanthramides are the primary bioactive components of colloidal oatmeal, a commonly used treatment to enhance skin barrier function. This study investigated the relationship between skin barrier function and epidermal characteristics and explored the potential of dihydroavenanthramide D (dhAvD), a synthetic avenanthramide, to improve the skin barrier. We observed a significant correlation between impaired skin barrier function and decreased epidermal thickness, suggesting that a weakened barrier contributes to increased sensitivity. Our in vitro results in HaCaT cells demonstrated that dhAvD enhances keratinocyte proliferation, migration, and tight junction protein expression, thereby strengthening the skin barrier. To mimic skin barrier dysfunction, we treated keratinocytes and full-thickness skin equivalents with IL-4 and IL-13, cytokines that are implicated in atopic dermatitis, and confirmed the downregulation of tight junction and differentiation markers. Furthermore, dhAvD treatment restored the barrier function and normalized the expression of key epidermal components, such as tight junction proteins and natural moisturizing factors, in keratinocytes treated with inflammatory cytokines. In the reconstructed human skin model, dhAvD promoted both epidermal and dermal restoration. These findings suggest that dhAvD has the potential to alleviate skin sensitivity and improve skin barrier function.

Dendrite intercalation between epidermal cells tunes nociceptor sensitivity to mechanical stimuli in Drosophila larvae.

An animal's skin provides a first point of contact with the sensory environment, including noxious cues that elicit protective behavioral responses. Nociceptive somatosensory neurons densely innervate and intimately interact with epidermal cells to receive these cues, however the mechanisms by which epidermal interactions shape processing of noxious inputs is still poorly understood. Here, we identify a role for dendrite intercalation between epidermal cells in tuning sensitivity of Drosophila larvae to noxious mechanical stimuli. In wild-type larvae, dendrites of nociceptive class IV da neurons intercalate between epidermal cells at apodemes, which function as body wall muscle attachment sites, but not at other sites in the epidermis. From a genetic screen we identified miR-14 as a regulator of dendrite positioning in the epidermis: miR-14 is expressed broadly in the epidermis but not in apodemes, and miR-14 inactivation leads to excessive apical dendrite intercalation between epidermal cells. We found that miR-14 regulates expression and distribution of the epidermal Innexins ogre and Inx2 and that these epidermal gap junction proteins restrict epidermal dendrite intercalation. Finally, we found that altering the extent of epidermal dendrite intercalation had corresponding effects on nociception: increasing epidermal intercalation sensitized larvae to noxious mechanical inputs and increased mechanically evoked calcium responses in nociceptive neurons, whereas reducing epidermal dendrite intercalation had the opposite effects. Altogether, these studies identify epidermal dendrite intercalation as a mechanism for mechanical coupling of nociceptive neurons to the epidermis, with nociceptive sensitivity tuned by the extent of intercalation.

Calpain Inhibition Protects against UVB-Induced Degradation of Dermal–Epidermal Junction–Associated Proteins

Calpain Inhibition Protects against UVB-Induced Degradation of Dermal–Epidermal Junction–Associated Proteins

Improving stability of human three dimensional skin equivalents using plasma surface treatment.

In developing three-dimensional (3D) human skin equivalents (HSEs), preventing dermis and epidermis layer distortion due to the contraction of hydrogels by fibroblasts is a challenging issue. Previously, a fabrication method of HSEs was tested using a modified solid scaffold or a hydrogel matrix in combination with the natural polymer coated onto the tissue culture surface, but the obtained HSEs exhibited skin layer contraction and loss of the skin integrity and barrier functions. In this study, we investigated the method of HSE fabrication that enhances the stability of the skin model by using surface plasma treatment. The results showed that plasma treatment of the tissue culture surface prevented dermal layer shrinkage of HSEs, in contrast to the HSE fabrication using fibronectin coating. The HSEs from plasma-treated surface showed significantly higher transepithelial electrical resistance compared to the fibronectin-coated model. They also expressed markers of epidermal differentiation (keratin 10, keratin 14 and loricrin), epidermal tight junctions (claudin 1 and zonula occludens-1), and extracellular matrix proteins (collagen IV), and exhibited morphological characteristics of the primary human skins. Taken together, the use of plasma surface treatment significantly improves the stability of 3D HSEs with well-defined dermis and epidermis layers and enhanced skin integrity and the barrier functions.

Calcitriol modulates epidermal tight junction barrier function in human keratinocytes

BackgroundThe aberrant expression of tight junction (TJ) proteins play an important role in several diseases with impaired skin barriers, including atopic dermatitis, psoriasis, and chronic wounds. The evidence provided thus far suggests an important role of calcitriol in skin homeostasis. However, it is not known whether calcitriol improves the impaired skin barrier. ObjectiveTo investigate the effect of calcitriol on TJ barrier function in human primary keratinocytes. MethodsNormal human primary keratinocytes were stimulated with calcitriol, and the expression of TJ-related proteins was measured by real-time PCR and Western blotting. Immunofluorescence was used to examine the intercellular distribution of TJ-related proteins. TJ barrier function was assessed by the transepithelial electrical resistance (TER) assay. ResultsWe demonstrated that calcitriol increased the expression levels of TJ-related proteins, including claudin-4, claudin-7, occludin, and zonula occludens (ZO)− 1. Calcitriol enhanced the distribution of TJ-related proteins at cellcell borders and induced the phosphorylation of pathways involved in the regulation of TJ barrier function, such as atypical protein kinase C (aPKC), Ras-related C3 botulinum toxin substrate 1 (Rac1), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt), as evidenced by the effects of specific inhibitors on the above pathways. Indeed, we confirmed that calcitriol enhanced TER in keratinocyte monolayers. ConclusionThese findings showed that calcitriol could modify the expression of keratinocyte TJ proteins, contributing to the maintenance of homeostatic barrier function.

Histopathological characteristics analysis of giant melanocytic naevi in children.

The major diagnostic criterion for the giant congenital melanocytic nevus (GCMN) is a size larger than 20 cm in diameter. However, the histopathological origin, pathogenesis, and GCMN progression are not yet completely clear. Unlike other medium or small superficial lesions, histomorphological evaluation is significant for GCMN pathological classification, malignant transformation assessment, and early detection of prognosis. This study aimed to investigate the pathological features of GCMN, including its satellite lesions. Twenty-three giant naevi and seventeen "satellite lesions" were collected from children aged 1 to 10 in Shanghai Ninth People's Hospital from 2018 to 2020. A histological study was conducted to evaluate their histological appearance. All the data observed and recorded data were statistically analyzed. In 23 cases of GCMN primary nevus, nevus cells were mainly distributed in the dermal region, with melanocyte proliferation and the presence of nevus nests at the dermal-epidermal junction. However, in satellite nevus, a junctional growth pattern was noted. Additionally, other histopathologic features, including epidermal contour, cell morphology, and architecture disorder also showed significant differences between primary nevus and satellite nevus. We demonstrated that the congenital pattern of the main nevus is more obvious than one of the satellite nevus, suggesting that the satellite nevus and the main nevus may occur slightly later than the main nevus. "Satellite nevus" happens as a result of a separate genetic event.

Line-field confocal optical coherence tomography coupled with artificial intelligence algorithms to identify quantitative biomarkers of facial skin ageing

Quantitative biomarkers of facial skin ageing were studied from one hundred healthy Caucasian female volunteers, aged 20–70 years, using in vivo 3D Line-field Confocal Optical Coherence Tomography (LC-OCT) imaging coupled with Artificial Intelligence (AI)-based quantification algorithms. Layer metrics, i.e. stratum corneum thickness (SC), viable epidermal thickness and Dermal–Epidermal Junction (DEJ) undulation, as well as cellular metrics were measured for the temple, cheekbone and mandible. For all three investigated facial areas, minimal age-related variations were observed in the thickness of the SC and viable epidermis layers. A flatter and more homogeneous epidermis (decrease in the standard deviation of the number of layers means), a less dense cellular network with fewer cells per layer (decrease in cell surface density), and larger and more heterogeneous nuclei within each layer (increase in nuclei volume and their standard deviation) were found with significant variations with age. The higher atypia scores further reflected the heterogeneity of nuclei throughout the viable epidermis. The 3D visualisation of fine structures in the skin at the micrometric resolution and the 1200 µm × 500 µm field of view achieved with LC-OCT imaging enabled to compute relevant quantitative biomarkers for a better understanding of skin biology and the ageing process in vivo.

Lentigo maligna and lentigo maligna melanoma in-vivo differentiation with dermoscopy and reflectance confocal microscopy: a retrospective, multi-center study.

Dermoscopic predictors of lentigo maligna (LM) and lentigo maligna melanoma (LMM) have been recently reported, but these have not been reported in reflectance confocal microscopy (RCM). (i) To validate dermoscopic predictors for LM/LMM, (ii) to identify RCM patterns in LM and LMM and (iii) correlations between dermoscopic and RCM features in LM and LMM. A retrospective, multicenter study of consecutive lesions with histologically proven LM or LMM subtypes of the head and face, with complete sets of dermoscopic and RCM images. A total of 180 lesions were included (n=40 LMM). Previously reported differential dermoscopic features for LM subtypes were confirmed. Other features significantly associated with LMM diagnosis included irregular hyperpigmented areas, shiny white streaks, atypical vessels, and light brown color at dermoscopy and medusa head-like structures, dermal nests and nucleated cells within the papillae at RCM (p<0.05). Correlations among LM lesions between dermoscopic and RCM features included brown to-gray dots and atypical cells (epidermis), grey color and inflammation and obliterated follicles and medusa head-like structures. Among LMM lesions, significant correlations included obliterated follicles with folliculotropism, both irregular hyperpigmented areas and irregular blotches with widespread atypical cell distribution (epidermis), dermal nests and nucleated cells within the papillae (dermis). Irregular blotches were also associated with medusa head-like structures (dermal epidermal junction [DEJ]). Dermoscopic and RCM features can assist in the in-vivo identification of LM histopathological subtypes and many are correlated. RCM 3-dimensional analysis of skin layers allows the identification of invasive components in the DEJ and dermis.

Melanin-dependent tissue interactions induced by a 755-nm picosecond-domain laser: complementary visualization by optical imaging and histology

Fractional picosecond-domain lasers (PSL) induce optical breakdown, which correlates histologically to vacuolization in the epidermis and dermis. In this ex vivo porcine study, we sought to establish a framework for the investigation of laser-tissue interactions and their dependence on melanin density. Light- (melanin index: 24.5 [0–100]), medium- (58.7), and dark-pigmented (> 98) porcine skin samples were exposed to a 755-nm fractional PSL and examined with dermoscopy, line-field confocal optical coherence tomography (LC-OCT), conventional OCT, and subsequently biopsied for digitally stained ex vivo confocal microscopy (EVCM) and histology, using hematoxylin and eosin (HE) and Warthin-Starry (WS) melanin staining. Dermoscopy showed focal whitening in medium- and dark-pigmented skin. Similarly, LC-OCT and OCT visualized melanin-dependent differences in PSL-induced tissue alterations. Vacuoles were located superficially in the epidermis in dark-pigmented skin but at or below the dermal–epidermal junction in medium-pigmented skin; in light-pigmented skin, no vacuoles were observed. Histology confirmed the presence of vacuoles surrounded by areas void of WS staining and disrupted stratum corneum in darker skin. The combined use of optical imaging for multiplanar visualization and histological techniques for examination of all skin layers may mitigate the effect of common artifacts and attain a nuanced understanding of melanin-dependent laser-tissue interactions.

Calcitriol, an Active Form of Vitamin D3, Mitigates Skin Barrier Dysfunction in Atopic Dermatitis NC/Nga Mice.

Atopic dermatitis and psoriasis are prevalent chronic inflammatory skin diseases that are characterized by dysfunctional skin barriers and substantially impact patients' quality of life. Vitamin D3 regulates immune responses and keratinocyte differentiation and improves psoriasis symptoms; however, its effects on atopic dermatitis remain unclear. Here, we investigated the effects of calcitriol, an active form of vitamin D3, on an NC/Nga mouse model of atopic dermatitis. We observed that the topical application of calcitriol decreased the dermatitis scores and epidermal thickness of NC/Nga mice with atopic dermatitis compared to untreated mice. In addition, both stratum corneum barrier function as assessed by the measurement of transepidermal water loss and tight junction barrier function as evaluated by biotin tracer permeability assay were improved following calcitriol treatment. Moreover, calcitriol treatment reversed the decrease in the expression of skin barrier-related proteins and decreased the expression of inflammatory cytokines such as interleukin (IL)-13 and IL-33 in mice with atopic dermatitis. These findings suggest that the topical application of calcitriol might improve the symptoms of atopic dermatitis by repairing the dysfunctional epidermal and tight junction barriers. Our results suggest that calcitriol might be a viable therapeutic agent for the treatment of atopic dermatitis in addition to psoriasis.

The Importance of Patient-Focused Drug Development in Pemphigus and Pemphigoid

The Importance of Patient-Focused Drug Development in Pemphigus and Pemphigoid

Successful Treatment of Lipoid Proteinosis in a Young Adult with Isotretinoin

Lipoid proteinosis (LP) is an extremely rare autosomal recessive genodermatosis, characterized by persistent hoarseness and classical skin lesions. Amorphous hyaline depositions may affect any organ, but mainly the face and extremities. These depositions cause limitations in tongue movement, and hence, difficulty speaking. Biopsies of skin lesions usually show massive deposits of homogeneous, acidic, hyaline-like material at the epidermal junctions and superficial dermis that stains positive for periodic acid-Schiff stain (PAS-D). At present, there is no specific treatment for this extremely rare disease, but some studies have reported that treatment with acitretin and etretinate results in some improvement. This paper reports on the effectiveness of isotretinoin for the first time for treatment of this disease.

The Fraser Complex Proteins (Frem1, Frem2, and Fras1) Can Form Anchoring Cords in the Absence of AMACO at the Dermal–Epidermal Junction of Mouse Skin

AMACO (VWA2 protein), secreted by epithelial cells, is strongly expressed at basement membranes when budding or invagination occurs in embryos. In skin, AMACO associates with proteins of the Fraser complex, which form anchoring cords. These, during development, temporally stabilize the dermal-epidermal junction, pending the formation of collagen VII-containing anchoring fibrils. Fraser syndrome in humans results if any of the core members of the Fraser complex (Fras1, Frem1, Frem2) are mutated. Fraser syndrome is characterized by subepidermal blistering, cryptophthalmos, and syndactyly. In an attempt to determine AMACO function, we generated and characterized AMACO-deficient mice. In contrast to Fraser complex mutant mice, AMACO-deficient animals lack an obvious phenotype. The mutually interdependent basement membrane deposition of the Fraser complex proteins, and the formation of anchoring cords, are not affected. Furthermore, hair follicle development in newborn AMACO-deficient mice showed no gross aberration. Surprisingly, it appears that, while AMACO is a component of the anchoring cords, it is not essential for their formation or function.

Diagnostic aid to subepidermal calcified nodule with dermoscopy and reflectance confocal microscopy: a case report

BackgroundSubepidermal calcified nodule (SCN) is a type of calcinosis cutis that usually occurs in children. The lesions in the SCN resemble those of other skin diseases, such as pilomatrixoma, molluscum contagiosum, and juvenile xanthogranuloma, leading to a high rate of misdiagnoses. Noninvasive in vivo imaging techniques, represented by dermoscopy and reflectance confocal microscopy (RCM), have dramatically accelerated skin cancer research over the past decade, and their applications have greatly expanded into other skin disorders. However, the features of an SCN in dermoscopy and RCM have yet to be reported previously. Combining these novel approaches with conventional histopathological examinations is a promising method for increasing diagnostic accuracy.Case presentationWe report on a case of SCN of the eyelid diagnosed with the aid of dermoscopy and RCM. A 14-year-old male patient who presented with a painless yellowish-white papule on his left upper eyelid was previously diagnosed with a common wart. Unfortunately, treatment with recombinant human interferon gel was not effective. To achieve a correct diagnosis, dermoscopy and RCM were performed. The former showed closely grouped multiple yellowish-white clods surrounded by linear vessels, and the latter exhibited hyperrefractile material nests at the dermal–epidermal junction level. The alternative diagnoses were, therefore, excluded because of in vivo characterizations. Subsequent surgical excision, histological examination, and von Kossa staining were performed. Pathology showed hyperkeratosis of the epidermis, a downward-directed basal-layer expansion, and small amorphous basophilic deposits scattered throughout the papillary dermis. The von Kossa staining confirmed calcium deposits in the lesion. An SCN was then diagnosed. During the 6-month follow-up, no relapse was observed.ConclusionsPatients with SCN could benefit from dermoscopy and RCM, which help achieve an accurate diagnosis. Clinicians should consider the possibility of an SCN for an adolescent patient with painless yellowish-white papules.

Coexistence of psoriasiform stratum corneum and underlying lichenoid features in skin biopsies of cutaneous reactions to anti-PD1.

Coexistence of psoriasiform stratum corneum and underlying lichenoid features in skin biopsies of cutaneous reactions to anti-PD1.

Radiation-Induced Localized Bullous Pemphigoid.

Radiation-Induced Localized Bullous Pemphigoid.

Recurrent hemorrhagic bullae of the oral mucosa

Recurrent hemorrhagic bullae of the oral mucosa

Targeted delivery of oxytetracycline to the epidermal cell junction and stomata for crop protection

A micronutrient-based nanosystem was utilized to target the delivery of oxytetracycline to the stomata and epidermal cell junctions. The findings have potential to significantly improve crop protection against surface-restricted pathogens.