Neutrophil-driven and interleukin-36γ-associated ocular surface inflammation in chronic Stevens-Johnson syndrome

PURPOSE

This study aims to elucidate the tear proteome and understand the underlying molecular mechanisms involved in the ocular complications following Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN).

METHODS

Mass spectrometry (MS) was performed to quantify the tear fluid proteins from chronic SJS/TEN patients (n = 22 eyes) and age- and gender-matched controls (n = 22 eyes). The candidate proteins were validated using ELISA (n = 80 eyes) in tear samples and immunohistochemistry (IHC; n = 12) in eyelid margin specimens. These proteins were compared for significant differences based on age, gender, disease duration, and ocular severity.

RESULTS

A total of 1692 tear fluid proteins were identified, of which 470 were significantly differentially regulated in chronic SJS/TEN. The top 10 significantly upregulated proteins were neutrophil secretions including neutrophil elastase (p < .0001), defensin (p < .0001), and matrix metalloproteinase 8 (p < .0001). The presence of neutrophils was confirmed by the upregulation of IL-8 (p < .001) in tears, a key cytokine known for recruiting neutrophils. Additionally, positive expression of myeloperoxidase was observed in the keratinized eyelid margins of SJS/TEN to validate the presence of neutrophils. Among 41 unique proteins identified by MS, IL-36γ (p < .01) was expressed in three SJS/TEN patients and was confirmed in SJS/TEN tears and eyelid margins by ELISA and IHC, respectively. IL-36γ was specifically expressed in the superficial layers of eyelid margin keratinized conjunctiva. The majority of the significantly downregulated proteins were lacrimal gland secretions such as lacritin (p < .0001) and opiorphin (p < .002). Neutrophil elastase (p < .02) was significantly elevated in patients with severe eyelid margin keratinization.

CONCLUSION

Our observations indicate a clear correlation between eyelid margin keratinization and the expression of IL-36γ, potentially mediated by neutrophils recruited via IL-8. Future experimental studies are needed to test the role of therapies targeting IL-8 and/or IL-36γ in reducing eyelid margin keratinization and its associated ocular complications in SJS/TEN.

Tongue microarchitecture and functional characterization of the lingual papillae in the desert hedgehog (Paraechinus aethiopicus)

The present work attempted to provide a comprehensive description of the morphoanatomical, histological, and ultrastructural characteristics of the tongue in the desert hedgehog (Paraechinus aethiopicus), and to correlate lingual modifications to the feeding lifestyle. Five adult male hedgehogs were utilized in our investigation. The macroscopic observations revealed elongated, with a moderately pointed apex, tongue and the tongue dorsum lacks both lingual prominence and median sulcus. The main subdivisions of the tongue are radix linguae (root), corpus linguae (body), and apex linguae (apex). The tongue dorsum carries two types of mechanical (conical and filiform) and gustatory (fungiform and circumvallate) papillae. The lingual apex is characterized by the existence of a unique encapsulated muscular structure. Additionally, the lingual glands were interposed between the muscular strands and no lingual glands were detected on the lingual apex. The dorsal surface of the lingual apex exhibited the highest level of keratinization as revealed by histochemical staining while the root showed moderate staining. The topography of the tongue was investigated by scanning electron microscopy (SEM). The obtained results are important to provide basic knowledge that can contribute to better understanding of the nourishment, feeding habits and behavior in this species. Furthermore, the addition of the newly investigated species may help us to determine the evolutionary relationships among species.

Challenges in the Diagnosis and Management of Giant Porokeratosis: A Case Report

Porokeratosis encompasses a diverse group of dermatoses, both acquired and genetic, marked by a keratinization disorder. Porokeratosis of Mibelli (PKM) presents as solitary plaques or multiple papules/macules with central atrophy and raised hyperkeratotic borders. Here, we present a case of giant porokeratosis (GPK), a rare form often considered a morphological variant of PKM, with unique clinical and histopathological aspects. Our case involves a 29-year-old patient with a 15 × 10 cm irregular plaque on the dorsal aspect of the right hand. The patient was previously prescribed various topical treatments (retinoids, calcineurin inhibitors, and combinations of corticosteroids with vitamin D3 analogs) and systemic retinoids without improvement before presenting to our department. Due to the high risk of neoplastic transformation and the unavailability of imiquimod, the patient was recommended topical 5-fluorouracil treatment. The trajectory of the lesion under treatment revealed a favorable evolution, and the patient was subjected to regular monitoring every three months to assess the ongoing progress. Recognizing GPK as a high-risk variant is crucial for dermatologists, and it requires a personalized approach. Regular monitoring is advised to detect potential malignant transformations promptly. Future research holds promise for diagnostic advancements, refined treatment modalities, and a deeper understanding of the molecular mechanisms underlying malignancy in porokeratosis.

Keratinization in atypical glandular cell clusters as a cytological clue to endometrioid carcinoma on cervical cytology

INTRODUCTION

Specific diagnosis of endometrial carcinomas on cervical cytology is difficult with few useful cytomorphological clues reported. This study reviews a cohort of cervical cytology to investigate the presence of keratinization in atypical glandular cells (AGC), an undescribed cytomorphological clue for identifying endometrial endometrioid carcinomas on cervical cytology.

METHODS

Cervical cytology slides from patients with a histologic diagnosis of endometrial endometrioid carcinoma were reviewed for the presence of keratinization associated with AGCs. Corresponding histology slides were reviewed for tumour grading and degree of squamous differentiation.

RESULTS

In total, 42 cases of cervical cytology specimens from 41 patients were retrieved, including 7 (16.7%) with keratinization associated with AGCs seen and 35 (83.3%) without. Comparison of histologic grading did not demonstrate an association with the presence of keratinization on cytology (p = 0.565). Corresponding histology slides were available for 37 cases. Cytologic and histologic keratinization were associated statistically (p = 0.002). Frank keratinization was seen on histologic slides of five cases, with four also showing cytologic keratinization. Area of squamous differentiation, including squamous morule formation, did not correlate with keratinization on cytologic preparation (p = 0.185).

CONCLUSION

Histologic and cytologic keratinization are observed in endometrioid endometrial carcinomas. Such is reflected in cervical cytology by the presence of orangeophilic, rigid and acellular fragments within or associated with AGC clusters. Keratinization, when identified with AGCs, should be regarded as a cytologic clue suggestive of an endometroid carcinoma of endometrial origin.

Immunohistochemistry in an Adult Case of Bitot's Spots Caused by Vitamin A Deficiency

Bitot's spots (BS) are the buildup of superficially located keratin in the conjunctiva and are early indicators of vitamin A deficiency (VAD), primarily due to malnutrition and malabsorption, thus leading to xerophthalmia. BS are particularly prevalent in developing countries, and their presence necessitates prompt vitamin A supplementation to avert blindness, with the immunohistochemical characteristics of BS aiding in understanding the extent of epithelial abnormalities and the efficacy of vitamin A supplementation. We describe the case of a 34-year-old male with persistent BS despite extensive vitamin A supplementation and topical treatments who underwent surgical excision of the BS followed by amniotic membrane transplantation, thus resulting in symptom relief and epithelialization, with no recurrence observed during follow-up. Histopathologic and immunohistochemical evaluations revealed expression of keratinization-related proteins, along with an absence of mucin-5AC-positive cells, suggesting impaired differentiation into goblet cells due to VAD. This case highlights the potential age-related disparity in the efficacy of vitamin A supplementation, emphasizing the need for early detection and a multidisciplinary approach in the management of VAD, especially in young adults. The favorable outcome of surgical intervention highlights its viability in the management of persistent BS and encourages further investigation to optimize therapeutic strategies for VAD-related ocular manifestations.

Inherited ichthyosis as a paradigm of rare skin disorders: Genomic medicine, pathogenesis, and management

Great advances have been made in the field of heritable skin disorders using next-generation sequencing (NGS) technologies (ie, whole-genome sequencing, whole-exome sequencing, whole-transcriptome sequencing, and disease-targeted multigene panels). When NGS first became available, the cost and lack of access to these technologies were limiting factors; however, with decreasing sequencing costs and the expanding knowledge base of genetic skin diseases, fundamental awareness of NGS has become prudent. The heritable ichthyoses comprise a genotypically and phenotypically heterogeneous group of monogenic keratinization disorders characterized by persistent scaling, with at least 55 distinct genes currently implicated in causing nonsyndromic and syndromic forms of the disease. By providing a simplified overview of available NGS techniques and applying them in the context of ichthyosis, one of the most common genodermatoses, we hope to encourage dermatologists to offer, when appropriate, genetic testing earlier in patients with unsolved presentations. With the aid of NGS, dermatologists can provide diagnostic certainty in cases of suspected genodermatoses and offer potentially life-changing genome-guided and targeted therapies as they become available.

"MrgprA3 neurons selectively control myeloid-derived cytokines for IL-17 dependent cutaneous immunity"

Skin employs interdependent cellular networks to facilitate barrier integrity and host immunity through ill-defined mechanisms. This study demonstrates that manipulation of itch-sensing neurons bearing the Mas-related G protein-coupled receptor A3 (MrgprA3) drives IL-17+ γδ T cell expansion, epidermal thickening, and resistance to the human pathogen Schistosoma mansoni through mechanisms that require myeloid antigen presenting cells (APC). Activated MrgprA3 neurons instruct myeloid APCs to downregulate interleukin 33 (IL-33) and up-regulate TNFα partially through the neuropeptide calcitonin gene related peptide (CGRP). Strikingly, cell-intrinsic deletion of IL-33 in myeloid APC basally alters chromatin accessibility at inflammatory cytokine loci and promotes IL-17/23-dependent epidermal thickening, keratinocyte hyperplasia, and resistance to helminth infection. Our findings reveal a previously undescribed mechanism of intercellular cross-talk wherein "itch" neuron activation reshapes myeloid cytokine expression patterns to alter skin composition for cutaneous immunity against invasive pathogens.

Comparison of Clinico-Demographic and Histological Parameters Between Young and Old Patients With Oral Squamous Cell Carcinoma

INTRODUCTION

Among the epithelial malignancies of the head and neck region, oral squamous cell carcinoma (OSCC) arising from the oral mucosa is the commonest type. OSCC is common in the older population; however, recent epidemiological data indicate an increase in the incidence in the younger age group. The present study was designed to compare the clinicopathological characteristics of OSCC between young and old South Indian patients.

METHODS

All the histopathologically confirmed cases of OSCC were retrieved from the department archives. Patients aged more than 40 years were considered Group I, and patients aged less than or equal to 40 were considered Group II. Age, gender, laterality, site, degree of keratinization, nuclear pleomorphism, pattern of invasion, lymphoplasmacytic infiltration, grade, tumor budding (TB), and tumor stroma ratio (TSR) were assessed.

RESULTS

Among 510 patients reported with OSCC, 442 were aged above 40 years, and 68 were aged 40 years or younger. Nuclear pleomorphism, TB, and stroma-rich ratio were statistically higher in younger OSCC patients (p=0.00).

CONCLUSION

The results of our study support the fact that OSCC in younger individuals is more aggressive. Targeting TB and tumor stroma could provide new strategies for the management of OSCC.

Expression profiling identifies key genes and biological functions associated with eosinophilic esophagitis in human patients

Introduction

Eosinophilic Esophagitis (EoE) is a chronic allergic disease characterized by progressive inflammation of the esophageal mucosa. This chronic inflammatory disorder affects up to 50 per 100,000 individuals in the United States and Europe yet is limited in treatment options. While the transcriptome of EoE has been reported, few studies have examined the genetics among a cohort including both adult and pediatric EoE populations. To identify potentially overlooked biomarkers in EoE esophageal biopsies that may be promising targets for diagnostic and therapeutic development.

Methods

We used microarray analysis to interrogate gene expression using esophageal biopsies from EoE and Control subjects with a wide age distribution. Analysis of differential gene expression (DEGs) and prediction of impaired pathways was compared using conventional transcriptome analysis (TAC) and artificial intelligence-based (ADVAITA) programs. Principal Components Analysis revealed samples cluster by disease status (EoE and Control) irrespective of clinical features like sex, age, and disease severity.

Results

Global transcriptomic analysis revealed differential expression of several genes previously reported in EoE (CCL26, CPA3, POSTN, CTSC, ANO1, CRISP3, SPINK7). In addition, we identified differential expression of several genes from the MUC and SPRR families, which have been limited in previous reports.

Discussion

Our findings suggest that there is epithelial dysregulation demonstrated by DEGs that may contribute to impaired barrier integrity and loss of epidermal cell differentiation in EoE patients. These findings present two new gene families, SPRR and MUC, that are differentially expressed in both adult and pediatric EoE patients, which presents an opportunity for a future therapeutic target that would be useful in a large demographic of patients.

Misdiagnosed Pityriasis Rubra Pilaris Successfully Managed With Isotretinoin: A Case Series

Being a rare inflammatory, hyperproliferative dermatosis, diagnosing pityriasis rubra pilaris (PRP) can be a challenge to many clinicians. Our case reports aim to demonstrate that PRP is frequently diagnosed and managed as atopic dermatitis (AD) and that distinguishing features on dermoscopy, and biopsy can help diagnose this rare disease. The study also aims to show that PRP can be successfully treated with Isotretinoin. Our case series aims to describe two cases of PRP, initially diagnosed as AD and managed with topical corticosteroids. Being the first case series in the literature to describe the incidences of diagnosing PRP as AD portrays the significance of utilizing dermoscopy and biopsy as tools to confirm this diagnosis for appropriate management. Although PRP is a rare diagnosis, dermoscopy and biopsy can help confirm the disease. Management with isotretinoin will most likely have successful outcomes in those patients.

Histology and Ultrastructure of the Esophagus in European Beaver (Castor fiber) Displays Features Adapted to Seasonal Changes in Diet

The European beaver is a herbivorous rodent whose diet changes seasonally, and in winter consists of large quantities of woody plants. It is distinguished among other mammals by a unique organization of the stomach that comprises the cardiogastric gland and by the unusual process of mucus formation in the gastric mucosa. The aim of study was to (i) characterize the structure of the beaver esophagus with particular attention to the mucosal epithelium; (ii) compare the histological structure of the esophagi collected in spring, summer, and winter; (iii) provide preliminary data on the structure of the esophagus in beaver fetuses. The study was conducted on esophagi of 18 adult beavers captured in Poland in April, August, and December, and on 3 fetal organs. The results obtained in adults show that the mucosa is lined with thick stratified squamous keratinized epithelium with a structure similar to that of the skin epidermis. Ultrastructural studies reveal the presence of multiple lamellar and non-lamellar bodies in granular cells, whose morphology and location gradually change while reaching the upper epithelial layers. The muscularis mucosa comprises a layer of longitudinally oriented bundles of smooth muscle cells. Both mucosa and submucosa do not comprise any glands. The thick muscularis externa consists mainly of internal circular and external longitudinal layers of striated muscle fibers. The keratinized layer of mucosa epithelium was 2-3-fold thicker in esophagi collected in winter than in those collected in spring and summer, while the epithelial cell layer thickness remained unchanged regardless of the season. Immunolabeling for proliferating cell nuclear antigen shows a higher index of epithelium proliferation in esophagi collected in winter than in spring and summer. No seasonal differences were noted in other layers of the esophagus. Fetal organs have epithelium covered with a keratinized layer, thinner than in adults, and the muscularis externa comprises both striated and smooth muscle cells.

Clinical efficacy of subepithelial connective tissue graft and A-PRF in the treatment of gingival recession

OBJECTIVE

The current study was designed to clinically compare and evaluate subepithelial connective tissue graft (SCTG) and advanced platelet-rich fibrin (A-PRF) membrane-based root coverage in the treatment of gingival recession type 1 (RT1).

METHOD AND MATERIALS

The current study involved 17 patients with bilateral gingival recession (RT1). Thirty-four sites were randomly allocated to test (A-PRF) and control (SCTG) sites and all the procedures were performed by a single operator. A single blinded observer evaluated the test and control sites at baseline, 3 months, and 6 months. The clinical parameters such as recession depth, recession width, width of keratinized gingiva, clinical attachment level, and percentage of root coverage were recorded. P < .05 was considered statistically significant.

RESULTS

The mean recession depth at baseline for control and test groups was 3.06 ± 0.56 mm and 2.35 ± 0.49 mm, respectively (P < .001). At the end of the study period, the mean recession depth was 0.53 ± 0.62 mm in the control group and 1.12 ± 0.49 mm in the test group (P < .05). No complications were associated with both the groups. The mean percentage of root coverage was 84.31 ± 17.89% in the control group and 51.96 ± 15.45% in the test group (P < .001).

CONCLUSION

In conclusion, the study results suggest that both SCTG and A-PRF can be used in treating gingival recessions. However, SCTG is a better material in achieving root coverage and increasing keratinized tissue width. (Quintessence Int 2023;54:134-141; doi: 10.3290/j.qi.b3512389).

Artificial Infestation of Sarcoptes scabiei (Acari: Sarcoptidae) in Rabbits Exhibits Progressive Pathological Changes, Apoptosis, and Keratinization in the Skin

Sarcoptes scabiei (S. scabiei) is an ectoparasite that can infest humans and 150 mammalian host species, primarily causing pruritus, crust, and alopecia. However, neither the pathological process of host skin under S. scabiei infection nor the mechanism of S. scabiei infection in regulating apoptosis and keratinization of host skin has been studied yet. In this study, a total of 56 rabbits were artificially infested with S. scabiei, and the skin samples were collected at seven different time points, including 6 h, 12 h, day 1, day 3, 1 week, 4 weeks, and 8 weeks, whereas a group of eight rabbits served as controls. We measured epidermal thickness by H&E staining, observed the skin ultrastructure by electron microscopy, and detected the degree of skin apoptosis by TUNEL staining. The level of transcription of genes related to apoptosis and keratinization was detected by quantitative real-time PCR (qRT-PCR), and the level of Bcl-2 protein expression was further detected using immunohistochemistry. Our results showed that, with increased infestation time, the epidermal layer of the rabbit skin exhibited significant thickening and keratinization, swollen mitochondria in the epidermal cells, and increased skin apoptosis. The level of caspase-1, 3, 8, 10, 14, and Bcl-2 mRNA expression was increased, whereas the level of keratin 1 and 5 was decreased after S. scabiei infestation. In conclusion, S. scabiei infestation causes thickening of the epidermis, which may be related to apoptosis-induced proliferation and skin keratinization.

Pilomatrix-like High-Grade Endometrioid Carcinoma of the Ovary: Case Report, Literature Review, and Differential Diagnosis

Pilomatrix-like high-grade endometrioid carcinoma (PiMHEC) has recently been described as an aggressive variant of endometrial carcinoma. Herein, we described a case of ovarian PiMHEC, comparing it to endometrial PiMHEC and assessing previously published cases of putative ovarian PiMHEC. A 65-year-old woman underwent hysterectomy for an ovarian tumor characterized by solid nests of basaloid cells with prominent ghost cell keratinization. Immunohistochemistry showed nuclear β-catenin and CDX2 expression and loss of estrogen and progesterone receptors and PAX8. These features were consistently observed in all previously published cases and may represent diagnostic criteria of PiMHEC. Other frequent features were geographic necrosis and a low-grade endometrioid component. CK7, neuroendocrine, and basal/squamous markers were inconsistently expressed. All cases with available follow-up showed poor prognosis. PiMHEC should be distinguished from mimickers, such as high-grade endometrioid carcinoma with geographic necrosis, low-grade endometrioid carcinoma with ghost cell keratinization, and undifferentiated/dedifferentiated carcinoma. In conclusion, PiMHEC can also occur in the ovary and shows several consistent clinical, morphological, and immunophenotypical features. These features support that PiMHEC is a distinct entity requiring an aggressive management.

Granular Parakeratosis: A Case Report

Granular parakeratosis is an uncommon acquired keratinization disorder that occurs in the armpit, groin, and other parts of the body. It may be related to stimulation by detergents and antiperspirants. This article reports a case of granular parakeratosis in the groin. The patient was a young man with no predisposing factors. The clinical manifestations included symmetrical bilateral inguinal erythema, dryness, and a small amount of bran-like desquamation. After histopathological examination, the final diagnosis was granular parakeratosis, which was cured by topical application of glucocorticoid cream and silicone oil cream. Granular parakeratosis is a rare skin disease of unknown etiology. Clinicians need to pay attention to this disease and differentiate it from various diseases to avoid misdiagnosis.

Management of Harlequin Ichthyosis: A Brief Review of the Recent Literature

Harlequin ichthyosis (HI) is a life-threatening genetic disorder that largely affects the skin of infants. HI is the most severe form of the autosomal recessive disorder known as ichthyosis. It is caused by mutations in the A12 cassette (lipid-transporter adenosine triphosphate-binding cassette A12). Neonates affected by this disease are born with specific morphological characteristics, the most prominent of which is the appearance of platelet keratotic scales separated by erythematous fissures. The facial features include eclabium, ectropion, a distinct flattened nose, and dysplastic ears. A common finding among those with HI is impaired skin barrier function. The purpose of the present narrative review is to assess the most recent literature regarding the management of HI. Emphasis is given to surgical management and consultation, to the indications for timing and surgical intervention, to the risks that are presented with surgery, and to the details of the surgical procedure itself. Management of HI requires a multidisciplinary team of experts, and specific guidelines are needed in order for the risks to be minimized and viability to be increased.

Macrophages in dermal disease progression of phospholipase D4-deficient Fleckvieh calves

A new gene defect in Fleckvieh calves leads to a syndrome with partial phenotype overlap with bovine hereditary zinc deficiency. A mutation in a gene encoding phospholipase D4 (PLD4), an endosomal exonuclease, causes the disorder. In mice, PLD4 activity indirectly regulates the Toll-like receptor 9 (TLR9) pathway via degradation of microbial DNA. PLD4 absence thus results in visceral macrophage activation comparable to human macrophage activation syndrome. In this study, disease progression and the role of macrophages in affected calves were monitored clinically, clinicopathologically, and histologically over time. Breeding data identified 73 risk matings of heterozygous carriers resulting in 54 potentially PLD4-deficient calves born on farms. PLD4 status was examined via 5'-exonuclease assay, detecting 6 calves carrying the defect. These were purchased and monitored daily until final necropsy. The calves developed progressive skin lesions starting with small scaling areas terminating in severe crusting dermatitis, especially in areas with mechanical exposure. Histological and immunohistochemical analyses indicated that macrophages with cytoplasmic vacuolation increased considerably in skin sections obtained weekly during the disease course. Macrophage increase correlated with increased dermal lesion severity. Macrophage activation was confirmed by prominent phagocytic activity in the superficial dermis using electron microscopy. Dermal mRNA abundance of CCL2 and CCL3 measured by quantitative polymerase chain reaction verified macrophage activation. Further increase in mRNA of downstream molecule MyD88 and cytokine IL12b connected bovine PLD4 deficiency to increased TLR9 pathway activation. In contrast to human macrophage activation syndrome, the main feature of bovine PLD4 deficiency was local disease in organs with contact to microbial DNA (skin, intestine, lungs).

Three-Dimensional Skin Tissue Printing with Human Skin Cell Lines and Mouse Skin-Derived Epidermal and Dermal Cells

Since the skin covers most surfaces of the body, it is susceptible to damage, which can be fatal depending on the degree of injury to the skin because it defends against external attack and protects internal structures. Various types of artificial skin are being studied for transplantation to repair damaged skin, and recently, the production of replaceable skin using three-dimensional (3D) bioprinting technology has also been investigated. In this study, skin tissue was produced using a 3D bioprinter with human skin cell lines and cells extracted from mouse skin, and the printing conditions were optimized. Gelatin was used as a bioink, and fibrinogen and alginate were used for tissue hardening after printing. Printed skin tissue maintained a survival rate of 90% or more when cultured for 14 days. Culture conditions were established using 8 mM calcium chloride treatment and the skin tissue was exposed to air to optimize epidermal cell differentiation. The skin tissue was cultured for 14 days after differentiation induction by this optimized culture method, and immunofluorescent staining was performed using epidermal cell differentiation markers to investigate whether the epidermal cells had differentiated. After differentiation, loricrin, which is normally found in terminally differentiated epidermal cells, was observed in the cells at the tip of the epidermal layer, and cytokeratin 14 was expressed in the lower cells of the epidermis layer. Collectively, this study may provide optimized conditions for bioprinting and keratinization for three-dimensional skin production.

Keratinization and Cornification are not equivalent processes but keratinization in fish and amphibians evolved into cornification in terrestrial vertebrates

The present account offers a generalized view of the evolution of process of terminal differentiation in keratinocytes of the epidermis in anamniotes, indicated as keratinization, into a further differentiating process of cornification in the skin and appendages of terrestrial vertebrates. Keratinization indicates the prevalent accumulation of intermediate filaments of keratins (IFKs) and is present in most fish and amphibian epidermis and inner epithelia of all vertebrates. During land adaptation, terrestrial vertebrates evolved a process of cornification and keratinocytes became dead corneocytes by the addition of numerous others proteins to the IFKs framework, represented by keratin-associated proteins (KAPs) and corneous proteins (CPs). Most of genes coding for these types of proteins are localized in chromosomal loci different and un-related from those of IFKs, and CPs originated from a gene cluster indicated as epidermal differentiation complex. During the evolution of reptiles and birds, the epidermis and corneous derivatives such as scales, claws, beaks and feathers mainly accumulate a type of CPs that overcome IFKs and containing a 34 amino acid beta-sheet core indicated as corneous beta proteins, formerly known as beta-keratins. Mammals did not evolve a beta-sheet core in their CPs and KAPs but instead produced numerous cysteine-rich IFKs in their epidermis and specialized KAPs in hairs, claws, nails, hooves and horns.

A Case Report of Mucoepidermoid Carcinoma With Extensive Keratinization in Parotid: Expanding the Morphologic Spectrum

Mucoepidermoid carcinoma (MEC) is the most common malignant tumor of salivary glands in children and young adults. Typically, it is composed of squamoid, mucin-producing and intermediate-types cells. However, overt keratinization is rare. To the best of our knowledge, extensive keratinization or keratin pearls in MEC has never been reported. Keratinization or keratin pearls are regard "practically never seen in low-grade MEC". Herein, we report a case of a 34-year-old woman who presented with a tumor in right parotid gland for 2 months. Microscopically, the tumor was composed of extensive squamous cells with overt keratin pearls, intermediate cells and few scattered mucous cells. MAML2 gene break-apart and CRTC1-MAML2 gene fusion were detected by fluorescence in situ hybridization. This is the first report to describe a MEC case with extensive squamous metaplasia and overt keratin pearls formation, which expands the morphologic spectrum of MEC.

Xerophthalmia with secondary malabsorption syndrome in a young lady

Delayed recognition and treatment of vitamin A deficiency (VAD) in adults leads to devastating complications. A 24-year-old woman presented with diarrhea, malaise, and shortness of breath. Her medical history included blunt abdominal trauma for which, she had bowel resection surgery and revision surgery within a year of the last surgery at the age of 8 years. She had difficulty in night vision and dry eyes. The best-corrected visual acuity was 6/18 in the BE. On slit-lamp examination in the both eyes (BE), the conjunctiva was thick, dry-looking with wrinkling, and the cornea had diffused superficial punctate keratitis and in the left eye, there was corneal xerosis of 1.5 × 1.5 mm. Tear film breakup time was 0-s in the BE. Schirmer's were 30 mm BE. The rest of the ocular examination was within normal limits. A clinical diagnosis of xerophthalmia secondary to malabsorption was made and treated with systemic vitamin A and intense lubrication. With time, ophthalmic conditions improved, but she died due to poor general wellbeing and repeated hospital-acquired infections. The infrequent presentation of VAD in adults and the unusual etiology in this patient make this case interesting, whereas its potentially devastating consequences highlight the importance of its early recognition, treatment, and regular follow up needed by both patient and physician in the community (general practitioner and ophthalmologists) for the prevention of VAD complications and poor prognosis.

Five Functional Aspects of the Epidermal Barrier

The epidermis is a living, multilayered barrier with five functional levels, including a physical, a chemical, a microbial, a neuronal, and an immune level. Altogether, this complex organ contributes to protect the host from external aggression and to preserve its integrity. In this review, we focused on the different functional aspects.

A Clinician's Guide to Topical Retinoids

Retinoids are defined as molecules that bind to and activate retinoic acid receptors to influence the proliferation and differentiation of cells. Topical retinoids have evolved over the past several decades, being used in multiple dermatological conditions. This review aims to differentiate between synthetic and natural retinoids, discuss the pharmacology behind topical retinoids, highlight clinical applications, and categorize all the commercially available agents, including combination products. Understanding retinoid affinities for unique receptor subtypes can impact clinical decisions, resulting in optimizing treatment and enhancing patient adherence.

Vertebrate keratinization evolved into cornification mainly due to transglutaminase and sulfhydryl oxidase activities on epidermal proteins: An immunohistochemical survey

The epidermis of vertebrates forms an extended organ to protect and exchange gas, water, and organic molecules with aquatic and terrestrial environments. Herein, the processes of keratinization and cornification in aquatic and terrestrial vertebrates were compared using immunohistochemistry. Keratins with low cysteine and glycine contents form the main bulk of proteins in the anamniote epidermis, which undergoes keratinization. In contrast, specialized keratins rich in cysteine-glycine and keratin associated corneous proteins rich in cysteine, glycine, and tyrosine form the bulk of proteins of amniote soft cornification in the epidermis and hard cornification in scales, claws, beak, feathers, hairs, and horns. Transglutaminase (TGase) and sulfhydryl oxidase (SOXase) are the main enzymes involved in cornification. Their evolution was fundamental for the terrestrial adaptation of vertebrates. Immunohistochemistry results revealed that TGase and SOXase were low to absent in fish and amphibian epidermis, while they increased in the epidermis of amniotes with the evolution of the stratum corneum and skin appendages. TGase aids the formation of isopeptide bonds, while SOXase forms disulfide bonds that generate numerous cross-links between keratins and associated corneous proteins, likely increasing the mechanical resistance and durability of the amniote epidermis and its appendages. TGase is low to absent in the beta-corneous layers of sauropsids but is detected in the softer but pliable alpha-layers of sauropsids, mammalian epidermis, medulla, and inner root sheath of hairs. SOXase is present in hard and soft corneous appendages of reptiles, birds, and mammals, and determines cross-linking among corneous proteins of scales, claws, beaks, hairs, and feathers.

Molecular Tumor Subtypes of HPV-Positive Head and Neck Cancers: Biological Characteristics and Implications for Clinical Outcomes

Until recently, research on the molecular signatures of Human papillomavirus (HPV)-associated head and neck cancers mainly focused on their differences with respect to HPV-negative head and neck squamous cell carcinomas (HNSCCs). However, given the continuing high incidence level of HPV-related HNSCC, the time is ripe to characterize the heterogeneity that exists within these cancers. Here, we review research thus far on HPV-positive HNSCC molecular subtypes, and their relationship with clinical characteristics and HPV integration into the host genome. Different omics data including host transcriptomics and epigenomics, as well as HPV characteristics, can provide complementary viewpoints. Keratinization, mesenchymal differentiation, immune signatures, stromal cells and oxidoreductive processes all play important roles.

"Structural imprinting" of the cutaneous immune effector function

Keratinization provides tolerance to desiccation and mechanical durability. Loricrin, which is an epidermal thiol-rich protein, efficiently stabilizes terminally differentiated keratinocytes and maintains redox homeostasis. The discovery of the largely asymptomatic loricrin knockout (LKO) phenotype decades ago was rather unpredicted. Nevertheless, when including redox-driven, NF-E2-related factor 2-mediated backup responses, LKO mice provide opportunities for the observation of altered or "quasi-normal" homeostasis. Specifically, given that the tissue structure, as well as the local metabolism, transmits immunological signals, we sought to dissect the consequence of truncated epidermal differentiation program from immunological perspectives. Through a review of the aggregated evidence, we have attempted to generate an integrated view of the regulation of the peripheral immune system, which possibly occurs within the squamous epithelial tissue with truncated differentiation. This synthesis might not only provide insights into keratinization but also lead to the identification of factors intrinsic to the epidermis that imprint the immune effector function.

The KEAP1/NRF2 Signaling Pathway in Keratinization

Keratinization is a tissue adaptation, but aberrant keratinization is associated with skin disorders such as ichthyoses, atopic dermatitis, psoriasis, and acne. The disease phenotype stems from the interaction between genes and the environment; therefore, an understanding of the adaptation machinery may lead to a new appreciation of pathomechanisms. The KEAP1/NRF2 signaling pathway mediates the environmental responses of squamous epithelial tissue. The unpredicted outcome of the Keap1-null mutation in mice allowed us to revisit the basic principle of the biological process of keratinization: sulfur metabolism establishes unparalleled cytoprotection in the body wall of terrestrial mammals. We summarize the recent understanding of the KEAP1/NRF2 signaling pathway, which is a thiol-based sensor-effector apparatus, with particular focuses on epidermal differentiation in the context of the gene-environment interaction, the structure/function principles involved in KEAP1/NRF2 signaling, lessons from mouse models, and their pathological implications. This synthesis may provide insights into keratinization, which provides physical insulation and constitutes an essential innate integumentary defense system.

Calcium-sensing receptor deletion in the mouse esophagus alters barrier function

Calcium-sensing receptor (CaSR) is the molecular sensor by which cells respond to small changes in extracellular Ca²⁺ concentrations. CaSR has been reported to play a role in glandular and fluid secretion in the gastrointestinal tract and to regulate differentiation and proliferation of skin keratinocytes. CaSR is present in the esophageal epithelium, but its role in this tissue has not been defined. We deleted CaSR in the mouse esophagus by generating keratin 5 CreER;CaSR^Flox+/+compound mutants, in which loxP sites flank exon 7 of CaSR gene. Recombination was initiated with multiple tamoxifen injections, and we demonstrated exon 7 deletion by PCR analysis of genomic DNA. Quantitative real-time PCR and Western blot analyses showed a significant reduction in CaSR mRNA and protein expression in the knockout mice (^EsoCaSR^-/-) as compared with control mice. Microscopic examination of ^EsoCaSR^-/- esophageal tissues showed morphological changes including elongation of the rete pegs, abnormal keratinization and stratification, and bacterial buildup on the luminal epithelial surface. Western analysis revealed a significant reduction in levels of adherens junction proteins E-cadherin and β catenin and tight junction protein claudin-1, 4, and 5. Levels of small GTPase proteins Rac/Cdc42, involved in actin remodeling, were also reduced. Ussing chamber experiments showed a significantly lower transepithelial resistance in knockout (KO) tissues. In addition, luminal-to-serosal-fluorescein dextran (4 kDa) flux was higher in KO tissues. Our data indicate that CaSR plays a role in regulating keratinization and cell-cell junctional complexes and is therefore important for the maintenance of the barrier function of the esophagus.NEW & NOTEWORTHY The esophageal stratified squamous epithelium maintains its integrity by continuous proliferation and differentiation of the basal cells. Here, we demonstrate that deletion of the calcium-sensing receptor, a G protein-coupled receptor, from the basal cells disrupts the structure and barrier properties of the epithelium.

Management of Ichthyosis: A Brief Review

The ichthyoses, also termed the disorders of keratinization, are a heterogenous group of skin diseases in which a distinctive horny layer arises secondary to excessive transepidermal water loss. Although occasionally acquired, the majority of ichthyoses are inherited and can be pinpointed to characteristic genetic mutations. Management depends on disease severity and includes topical agents and lifestyle modifications with or without oral retinoids. Genetic counseling is also an important consideration. This review aims to highlight advances in our understanding of disease pathogenesis as well as the holistic approach necessary to adequately manage ichthyosis patients.

The Role of Fgf Signaling on Epithelial Cell Differentiation in Mouse Vagina

BACKGROUND/AIM

The mouse vagina exhibits stratified squamous epithelium, which is comprised of multiple cell layers. We previously showed that erbB signaling, induced by epithelial estrogen receptor 1 (ESR1), is required for the initial differentiation of the epithelium. However, the downstream effector that mediates terminal differentiation in the apical layers remains elusive. The contribution of fibroblast growth factor (FGF) to vaginal epithelial cell differentiation was investigated.

MATERIALS AND METHODS

Vaginas from wild-type or epithelium-specific Esr1 conditional knockout (cKO) mice were analyzed using immunohistochemistry and quantitative real-time RT-PCR.

RESULTS

Of the FGF ligands examined, Fgf22 mRNA was significantly induced following estrogen treatment. Furthermore, FGF downstream signaling, phosphorylated FRS2 and ERK1/2 were exclusively expressed in the apical layers of the vaginal epithelium. No changes in such expression were observed in the Esr1 cKO mice.

CONCLUSION

FGF-ERK/MAPK pathway may be a main inducer of terminal differentiation in the mouse vaginal epithelium.

A clinical evaluation on the effect of astringent on keratinization of oral mucosa before and after the insertion of complete denture

Context

Conventional complete dentures still remain a viable method of treatment for many patients in this era of fixed prosthesis like dental implants. All patients undergoing complete denture treatment need nonsurgical preprosthetic treatment for the preparation of healthy denture bearing mucosa as well-keratinized healthy mucosa is desirable for a complete denture.

Aims

To evaluate and compare the keratinization before and after denture insertion at intervals of 1 week and 1 month.

Settings and Design

The present study was conducted on 24 completely edentulous male subjects divided into control and study groups. Each patient in study group was asked to massage with astringent on the denture bearing mucosa over a 4-week period.

Subjects and Methods

Exfoliative cytology was used to collect the surface cells from the palatal mucosa and buccal mucosa. The first smear was taken before the denture insertion. The second and third smears were taken after the stimulation treatment with astringent gel for each patient after 1 week and after 4 weeks. Each smear was stained with the Papanicolaou's technique. The number of basal cells, intermediate cells, and superficial cells were recorded to calculate the degree of keratinization.

Statistical Analysis Used

Descriptive statistics, paired samples t-test, independent t-test, and repeated-measures analysis of variance.

Results

The result showed statistically significant increase in the keratinization of palatal mucosa after 4 weeks of astringent therapy and no effect was noted in the keratinization of buccal mucosa.

Conclusions

Astringent has shown to increase keratinization of palatal mucosa, and so it can be used to increase the quality of the denture bearing mucosa; moreover, the astringent stimulation has no effect on the keratinization of buccal mucosa.

Shared gene signature between pterygium and meibomian gland dysfunction uncovered through gene-expression meta-analysis

BACKGROUND

Pterygium and meibomian gland dysfunction (MGD) are two clinically correlated ocular diseases. We propose to investigate the shared gene signature between pterygium and MGD.

METHODS

Microarray datasets were retrieved from the Gene Expression Omnibus (GEO) database. Initial processing of the data was performed using the R programming package. Gene-expression values were log2 transformed and normalized by quantile normalization. The differentially expressed genes (DEGs) in each individual dataset were analyzed by the limma package. The integration of different pterygium datasets and gene-expression meta-analysis was conducted by the NetworkAnalyst package. A Venn diagram was created to find the overlapped DEGs between MGD and pterygium datasets. Gene ontology enrichment and pathway analysis were performed using the ToppGene Suite.

RESULTS

We found 193 DEGs significantly up-regulated in pterygium, with the combined effect sizes ranging from 1.53 to 3.78. A gene signature consisting of 11 DEGs were found to be shared by pterygium and MGD (SPRR3, SERPINB13, NMU, KRT10, IL37, KRT6B, PI3, S100A2, MAL, AURKA, and RGCC), and bioinformatics analyses showed that these overlapped DEGs were significantly enriched in pathways related to keratinization, cell-cycle regulation, and formation of the cornified envelope.

CONCLUSION

We identified a shared gene signature between pterygium and MGD through gene-expression meta-analysis. The analysis of this signature underlined that keratinization-related pathways may play important roles in the development of these two clinically correlated pathologies.

Inflammatory cytokine-mediated induction of serine racemase in atopic dermatitis

Serine racemase (SR) is an enzyme that catalyses the synthesis of d‐serine, an endogenous coagonist for N‐methyl‐D‐aspartate (NMDA)‐type glutamate receptor in the central nervous system. Our previous study demonstrated that SR was expressed in the epidermis of wild‐type (WT) mice but not in SR knockout (KO) mice. In addition, SR immune‐reactivity was only found in the granular and cornified layers of the epidermis in WT mice. These findings suggested that SR is involved in the differentiation of epidermal keratinocytes and the formation of the skin barrier. However, its role in skin barrier dysfunction such as atopic dermatitis (AD) remains elusive. AD is a chronic inflammatory disease of skin, and the clinical presentation of AD has been reported to be occasionally associated with psychological factors. Therefore, this study examined the content of d‐serine in stratum corneum in AD patients and healthy controls using a tape‐stripping method. Skin samples were collected from the cheek and upper arm skin of AD patient's lesion and healthy individuals. The d‐serine content was significantly increased in the involved skin of AD in comparison with healthy individuals. An immunohistochemical analysis also revealed an increased SR expression in the epidermis of AD patients. Furthermore, the SR expression in cultured human keratinocytes was significantly increased by the stimulation with tumour necrosis factor ‐α or macrophage migration inhibitory factor. Taken together, these findings suggest that d‐serine expressed particularly strongly in AD lesional skin and that the SR expression in the keratinocytes is linked to inflammatory cytokines.

Anthelmintic mebendazole enhances cisplatin's effect on suppressing cell proliferation and promotes differentiation of head and neck squamous cell carcinoma (HNSCC)

Head and neck squamous cell carcinoma (HNSCC) is one of the most common and aggressive types of human cancers worldwide. Nearly a half of HNSCC patients experience recurrence within five years of treatment and develop resistance to chemotherapy. Thus, there is an urgent clinical need to develop safe and novel anticancer therapies for HNSCC. Here, we investigate the possibility of repurposing the anthelmintic drug mebendazole (MBZ) as an anti-HNSCC agent. Using the two commonly-used human HNSCC lines CAL27 and SCC15, we demonstrate MBZ exerts more potent anti-proliferation activity than cisplatin in human HNSCC cells. MBZ effectively inhibits cell proliferation, cell cycle progression and cell migration, and induces apoptosis of HNSCC cells. Mechanistically, MBZ can modulate the cancer-associated pathways including ELK1/SRF, AP1, STAT1/2, MYC/MAX, although the regulatory outcomes are context-dependent. MBZ also synergizes with cisplatin in suppressing cell proliferation and inducing apoptosis of human HNSCC cells. Furthermore, MBZ is shown to promote the terminal differentiation of CAL27 cells and keratinization of CAL27-derived xenograft tumors. Our results are the first to demonstrate that MBZ may exert its anticancer activity by inhibiting proliferation while promoting differentiation of certain HNSCC cancer cells. It's conceivable the anthelmintic drug MBZ can be repurposed as a safe and effective agent used in combination with other frontline chemotherapy drugs such as cisplatin in HNSCC treatment.

Differential diagnosis of well-differentiated squamous cell carcinoma from non-neoplastic oral mucosal lesions: New cytopathologic evaluation method dependent on keratinization-related parameters but not nuclear atypism

BACKGROUND

The cytology of oral squamous cell carcinoma (SCC) is challenging because oral SCC cells tend to be well differentiated and lack nuclear atypia, often resulting in a false negative diagnosis. The purpose of this study was to establish practical cytological parameters specific to oral SCCs.

METHODS

We reviewed 123 cases of malignancy and 53 of non-neoplastic lesions of the oral mucosa, which had been diagnosed using both cytology and histopathology specimens. From those, we selected 12 SCC and 4 CIS cases that had initially been categorized as NILM to ASC-H with the Bethesda system, as well as 4 non-neoplastic samples categorized as LSIL or ASC-H as controls, and compared their characteristic findings. After careful examinations, we highlighted five cytological parameters, as described in Results. Those 20 cytology samples were then reevaluated by 4 independent examiners using the Bethesda system as well as the 5 parameters.

RESULTS

Five cytological features, (i) concentric arrangement of orangeophilic cells (indicating keratin pearls), (ii) large number of orangeophilic cells, (iii) bizarre-shaped orangeophilic cells without nuclear atypia, (iv) keratoglobules, and (v) uneven filamentous cytoplasm, were found to be significant parameters. All malignant cases contained at least one of those parameters, while none were observed in the four non-neoplastic cases with nuclear atypia. In reevaluations, the Bethesda system did not help the screeners distinguish oral SCCs from non-neoplastic lesions, while use of the five parameters enabled them to make a diagnosis of SCC.

CONCLUSION

Recognition of the present five parameters is useful for oral SCC cytology. Diagn. Cytopathol. 2017;45:406-417. © 2017 Wiley Periodicals, Inc.

Recent advances in understanding ichthyosis pathogenesis

The ichthyoses, also known as disorders of keratinization (DOK), encompass a heterogeneous group of skin diseases linked by the common finding of abnormal barrier function, which initiates a default compensatory pathway of hyperproliferation, resulting in the characteristic clinical manifestation of localized and/or generalized scaling. Additional cutaneous findings frequently seen in ichthyoses include generalized xerosis, erythroderma, palmoplantar keratoderma, hypohydrosis, and recurrent infections. In 2009, the Ichthyosis Consensus Conference established a classification consensus for DOK based on pathophysiology, clinical manifestations, and mode of inheritance. This nomenclature system divides DOK into two main groups: nonsyndromic forms, with clinical findings limited to the skin, and syndromic forms, with involvement of additional organ systems. Advances in next-generation sequencing technology have allowed for more rapid and cost-effective genetic analysis, leading to the identification of novel, rare mutations that cause DOK, many of which represent phenotypic expansion. This review focuses on new findings in syndromic and nonsyndromic ichthyoses, with emphasis on novel genetic discoveries that provide insight into disease pathogenesis.

Epithelial estrogen receptor 1 intrinsically mediates squamous differentiation in the mouse vagina

Estrogen-mediated actions in female reproductive organs are tightly regulated, mainly through estrogen receptor 1 (ESR1). The mouse vaginal epithelium cyclically exhibits cell proliferation and differentiation in response to estrogen and provides a unique model for analyzing the homeostasis of stratified squamous epithelia. To address the role of ESR1-mediated tissue events during homeostasis, we analyzed mice with a vaginal epithelium-specific knockout of Esr1 driven by keratin 5-Cre (K5-Esr1KO). We show here that loss of epithelial ESR1 in the vagina resulted in aberrant epithelial cell proliferation in the suprabasal cell layers and led to failure of keratinized differentiation. Gene expression analysis showed that several known estrogen target genes, including erbB growth factor ligands, were not induced by estrogen in the K5-Esr1KO mouse vagina. Organ culture experiments revealed that the addition of erbB growth factor ligands, such as amphiregulin, could activate keratinized differentiation in the absence of epithelial ESR1. Thus, epithelial ESR1 integrates estrogen and growth factor signaling to mediate regulation of cell proliferation in squamous differentiation, and our results provide new insights into estrogen-mediated homeostasis in female reproductive organs.

Epidemiology, medical genetics, diagnosis and treatment of harlequin ichthyosis in Japan

Ichthyoses are a group of disorders marked by whitish, brown or dark-brown scales on the skin of almost the whole body. Harlequin ichthyosis (HI) is the most severe form. Neonatal death from HI was once common. Due to intensive neonatal care and, probably, to the early introduction of oral retinoids, HI outcome has improved. For definitive diagnosis and the exclusion of other disorders, such as lamellar ichthyosis, which also shows a collodion baby phenotype, it is helpful to refer to electron microscopy of abnormal or absent lamellar granules and a heavy accumulation of lipid droplets in the keratinocytes. ATP-binding cassette transporter A12 (ABCA12) is known as the causative gene of HI. Severe ABCA12 deficiency results in malformation of intercellular lipid layers in the cornified layers and leads to epidermal lipid barrier disruption. In HI patients, at least one mutation on each allele must be a truncation or deletion mutation to cause serious loss of ABCA12 function. Identification of the gene underlying HI has enabled DNA-based prenatal diagnosis for HI at the earlier stages of pregnancy with low risk. There are no curative treatments for HI. Abca12-deficient mice were created as a model of HI. Treatment of the model mice with retinoid or steroid has not been successful.

Latent transforming growth factor-β binding proteins (LTBP-1 and LTBP-2) and gingiva keratinization

OBJECTIVE

Transforming growth factor-beta (TGF-β) proteins are involved in epithelial keratinization. The major function of latent TGF-β binding proteins (LTBPs) is modulating TGF-β activity. However, whether LTBP-1 and LTBP-2 play roles in gingiva keratinization remains unclear.

MATERIALS AND METHODS

Human keratinized gingiva and non-keratinized alveolar mucosa were processed for LTBP-1, LTBP-2, cytokeratin-1 (K1), cytokeratin-4 (K4), and TGF-β immunohistochemical (IHC) staining. Porcine heterotopically transplanted connective tissues and newly grown epithelia were harvested for IHC staining. The expression levels of LTBP-1 and LTBP-2 were compared between differentiated and undifferentiated human normal oral keratinocytes (hNOK). The expression of LTBP-1 and LTBP-2 was knocked down in a cell line (OEC-M1) to evaluate the effects on the expression of K1, K4, and involucrin (INV).

RESULTS

In human and porcine specimens, LTBP-2 expression patterns distinguished keratinized and non-keratinized oral epithelia. Western blotting results showed that K1, LTBP-1, and INV proteins were upregulated in differentiated hNOK. In OEC-M1 cells, LTBP-2 knockdown resulted in upregulated the expression of K1 and INV and downregulated the expression of K4. LTBP-1 knockdown resulted in opposite effects.

CONCLUSION

The expression patterns of LTBP-2 differ in keratinized gingiva and non-keratinized mucosa. LTBP-1 and LTBP-2 are involved in the keratinization of oral epithelium; however, the underlying mechanism remains to be elucidated.

Population diversity and adaptive evolution in keratinization genes: impact of environment in shaping skin phenotypes

Several studies have demonstrated the role of climatic factors in shaping skin phenotypes, particularly pigmentation. Keratinization is another well-designed feature of human skin, which is involved in modulating transepidermal water loss (TEWL). Although this physiological process is closely linked to climate, presently it is not clear whether genetic diversity is observed in keratinization and whether this process also responds to the environmental pressure. To address this, we adopted a multipronged approach, which involved analysis of 1) copy number variations in diverse Indian and HapMap populations from varied geographical regions; 2) genetic association with geoclimatic parameters in 61 populations of dbCLINE database in a set of 549 genes from four processes namely keratinization, pigmentation, epidermal differentiation, and housekeeping functions; 3) sequence divergence in 4,316 orthologous promoters and corresponding exonic regions of human and chimpanzee with macaque as outgroup, and 4) protein sequence divergence (Ka/Ks) across nine vertebrate classes, which differ in their extent of TEWL. Our analyses demonstrate that keratinization and epidermal differentiation genes are under accelerated evolution in the human lineage, relative to pigmentation and housekeeping genes. We show that this entire pathway may have been driven by environmental selection pressure through concordant functional polymorphisms across several genes involved in skin keratinization. Remarkably, this underappreciated function of skin may be a crucial determinant of adaptation to diverse environmental pressures across world populations.

Autosomal Recessive Congenital Ichthyosis in American Bulldogs Is Associated With NIPAL4 (ICHTHYIN) Deficiency

A minority of patients with nonsyndromic autosomal recessive congenital ichthyosis (ARCI) display mutations in NIPAL4 (ICHTHYIN). This protein plays a role in epidermal lipid metabolism, although the mechanism is unknown. The study describes a moderate form of ARCI in an extended pedigree of American Bulldogs that is linked to the gene encoding ichthyin. The gross phenotype was manifest as a disheveled pelage shortly after birth, generalized scaling, and adherent brown scale with erythema of the abdominal skin. Pedigree analysis indicated an autosomal recessive mode of inheritance. Ultrastructurally, the epidermis showed discontinuous lipid bilayers, unprocessed lipid within corneocytes, and abnormal lamellar bodies. Linkage analysis, performed by choosing simple sequence repeat markers and single-nucleotide polymorphisms near genes known to cause ACRI, revealed an association with NIPAL4. NIPAL4 was identified and sequenced using standard methods. No mutation was identified within the gene, but affected dogs had a SINE element 5' upstream of exon 1 in a highly conserved region. Of 545 DNA samples from American Bulldogs, 32 dogs (17 females, 15 males) were homozygous for the polymerase chain reaction fragment. All affected dogs were homozygous, with parents heterozygous for the insertion. Immunolabeling revealed an absence of ichthyin in the epidermis. This is the first description of ARCI associated with decreased expression of NIPAL4 in nonhuman species.

Histopathological analysis of apoptotic cell count and its role in oral lichen planus

AIM OF THE STUDY

To identify and count the number of apoptotic cells in oral lichen planus (OLP) and correlate with the degree of keratinization, thickness of epithelium and thickness of lymphocytic infiltration of OLP.

MATERIALS AND METHODS

The study comprised 40 diagnosed cases of OLP. Sections were stained with hematoxylin and eosin to identify and count the number of apoptotic cells. Measurement of other histopathological parameter of OLP such as degree of keratinization, thickness of epithelium and thickness of lymphocytic infiltration was done by using stage micrometer and eyepiece graticule. Statistical analysis was done to understand the correlation between apoptotic cells and histopathological features of OLP.

RESULT

The result showed that the number of apoptotic cells increased, with an increase in thickness of lymphocytic infiltration and degree of keratinization, but there was a decrease in the epithelial thickness.

CONCLUSION

Further immunological and molecular studies are required for a stronger evidence in correlating apoptotic cell and histological parameters of OLP.

Desmogleins: hair perspective

Desmogleins (Dsgs) are calcium-dependent, transmembrane glycoproteins belonging to the desmosomal cadherin superfamily, which play significant roles in selective calcium ions (Ca²⁺) dependent adhesion interactions between cell surfaces. Four subtypes of Dsg have been identified. Recent observations show the distribution of Dsgs can correlate with specific types of keratinization, anchorage of the hair, and hypotrichosis.

Keratoameloblastoma of the mandible

Keratoameloblastoma is a very rare ameloblastoma variant defined by extensive squamous metaplasia and keratinization. There are 13 previously reported cases in the literature, with a male predilection of 3:1. A 38-year-old male presented with a painless mandibular swelling which had been progressively increasing in size for 18 months. The incisional biopsy was misdiagnosed as basaloid squamous carcinoma. Owing to financial constraints, the patient had mandibular resection a decade after first noticing the growth, during which the clinical course was essentially benign, thus casting doubt on the initial diagnosis. The final histological diagnosis for both the incisional and resection biopsy specimens was keratoameloblastoma.

Evolution of the structure and function of the vertebrate tongue

Studies of the comparative morphology of the tongues of living vertebrates have revealed how variations in the morphology and function of the organ might be related to evolutional events. The tongue, which plays a very important role in food intake by vertebrates, exhibits significant morphological variations that appear to represent adaptation to the current environmental conditions of each respective habitat. This review examines the fundamental importance of morphology in the evolution of the vertebrate tongue, focusing on the origin of the tongue and on the relationship between morphology and environmental conditions. Tongues of various extant vertebrates, including those of amphibians, reptiles, birds and mammals, were analysed in terms of gross anatomy and microanatomy by light microscopy and by scanning and transmission electron microscopy. Comparisons of tongue morphology revealed a relationship between changes in the appearance of the tongue and changes in habitat, from a freshwater environment to a terrestrial environment, as well as a relationship between the extent of keratinization of the lingual epithelium and the transition from a moist or wet environment to a dry environment. The lingual epithelium of amphibians is devoid of keratinization while that of reptilians is keratinized to different extents. Reptiles live in a variety of habitats, from seawater to regions of high temperature and very high or very low humidity. Keratinization of the lingual epithelium is considered to have been acquired concomitantly with the evolution of amniotes. The variations in the extent of keratinization of the lingual epithelium, which is observed between various amniotes, appear to be secondary, reflecting the environmental conditions of different species.

Defective stratum corneum and early neonatal death in mice lacking the gene for transglutaminase 1 (keratinocyte transglutaminase)

The stratum corneum of the skin serves as an effective barrier for maintenance of the internal milieu against the external environment. At the cell periphery of the stratum corneum is the cell envelope, a highly insoluble membranous structure composed of precursor proteins cross-linked by epsilon-(gamma-glutamyl)lysine bonds. Transglutaminase 1 (TGase 1; keratinocyte TGase), a membrane-bound isozyme of the TGase family, has been proposed to catalyze this process of assembly. Deficient cross-linking of the cell envelope in some patients with the autosomal recessive skin disorder lamellar ichthyosis (LI) and several mutations of the TGase 1 gene that have been identified in families with LI suggest the importance of this gene in production of the cell envelope. In this study, we generated mice lacking the TGase 1 gene, and we report that they have erythrodermic skin with abnormal keratinization. In their stratum corneum, degradation of nuclei and keratohyalin F-granules was incomplete and cell envelope assembly was defective. The skin barrier function of TGase 1-null mice was markedly impaired, and these mice died within 4-5 h after birth. These results clearly demonstrate that the TGase 1 gene is essential to the development and maturation of the stratum corneum and to adaptation to the environment after birth. Thus, these TGase 1 knockout mice may be a useful model for severe cases of LI.