Desmocollin 1 and desmoglein 1 expression in human epidermis and keratinizing oral mucosa: a comparative immunohistochemical and molecular study

Analysis of transcriptional changes in the immune system associated with pubertal development in a longitudinal cohort of children with asthma

Puberty is an important developmental period marked by hormonal, metabolic and immune changes. Puberty also marks a shift in sex differences in susceptibility to asthma. Yet, little is known about the gene expression changes in immune cells that occur during pubertal development. Here we assess pubertal development and leukocyte gene expression in a longitudinal cohort of 251 children with asthma. We identify substantial gene expression changes associated with age and pubertal development. Gene expression changes between pre- and post-menarcheal females suggest a shift from predominantly innate to adaptive immunity. We show that genetic effects on gene expression change dynamically during pubertal development. Gene expression changes during puberty are correlated with gene expression changes associated with asthma and may explain sex differences in prevalence. Our results show that molecular data used to study the genetics of early onset diseases should consider pubertal development as an important factor that modifies the transcriptome.

Mechanisms Causing Acantholysis in Pemphigus-Lessons from Human Skin

Pemphigus vulgaris (PV) is an autoimmune bullous skin disease caused primarily by autoantibodies (PV-IgG) against the desmosomal adhesion proteins desmoglein (Dsg)1 and Dsg3. PV patient lesions are characterized by flaccid blisters and ultrastructurally by defined hallmarks including a reduction in desmosome number and size, formation of split desmosomes, as well as uncoupling of keratin filaments from desmosomes. The pathophysiology underlying the disease is known to involve several intracellular signaling pathways downstream of PV-IgG binding. Here, we summarize our studies in which we used transmission electron microscopy to characterize the roles of signaling pathways in the pathogenic effects of PV-IgG on desmosome ultrastructure in a human ex vivo skin model. Blister scores revealed inhibition of p38MAPK, ERK and PLC/Ca2+ to be protective in human epidermis. In contrast, inhibition of Src and PKC, which were shown to be protective in cell cultures and murine models, was not effective for human skin explants. The ultrastructural analysis revealed that for preventing skin blistering at least desmosome number (as modulated by ERK) or keratin filament insertion (as modulated by PLC/Ca2+) need to be ameliorated. Other pathways such as p38MAPK regulate desmosome number, size, and keratin insertion indicating that they control desmosome assembly and disassembly on different levels. Taken together, studies in human skin delineate target mechanisms for the treatment of pemphigus patients. In addition, ultrastructural analysis supports defining the specific role of a given signaling molecule in desmosome turnover at ultrastructural level.

Derma-Hc, a New Developed Herbal Formula, Ameliorates Cutaneous Lichenification in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic cutaneous disorder that is characterized by severe eczematous inflammation, swelling, and lichenification. Activation of T helper (Th)-22 cells by allergens leads to epidermal hyperplasia with hyperkeratosis at the chronic phase of AD. Derma-Hc is composed of five natural herbs with anti-AD effects, such as Astragalus membranaceus BUNGE, Schizonepeta tenuifolia Briq., Cryptotympana pustulata Fabr., Angelica sinensis Diels, Arctium lappa L. In this study, the ameliorative effect of Derma-Hc on cutaneous lichenification in 2,4-dinitrochlorobenzne (DNCB)-induced AD was investigated. The dorsal skin of mice was sensitized with DNCB to induce AD-like skin lesions. The dermatitis score and frequency of scratching were evaluated. Thickness of epidermis and dermis was measured by staining with H&E. In addition, infiltration of the mast cell was observed by staining with toluidine blue. Then, desmosomal cadherin, DSC1 was examined by immunofluorescence. Pathological mechanisms involved in lichenification were analyzed in AD-like skin lesions and TNF-α + IFN-γ-treated with human keratinocytes including keratinocyte differentiation genes and JAK1-STAT3 signaling pathway with IL-22 by RT-PCR and western blotting. Topical treatment of Derma-Hc improved AD-like symptoms such as dryness, edema and lichenefication and decreased the number of scratches. Histopathological analysis demonstrated that Derma-Hc significantly inhibited epidermal hyperplasia, hyperkeratosis, and mast cells infiltration. In addition, the level of DSC1 was highly expressed in the epidermis by Derma-Hc. Moreover, mRNA expression level of FLG, an epidermal differentiation complex gene, was recovered by Derma-Hc treatment. KLK5 and KLK7 were markedly reduced to normalize keratinocyte differentiation in dorsal skin tissues and human keratinocytes. On the other hand, Derma-Hc restored expression level of SPINK5. In addition, Derma-Hc inhibited IL-22 via the blockade of JAK1-STAT3 signal pathway. Taken together, Derma-Hc, a natural herbal formula, regulated keratinocyte differentiation and inhibited epidermal hyperplasia with hyperkeratosis. Therefore, Derma-Hc could be a promising candidate for treating chronic AD through modulating signaling of IL-22-associated skin lichenification.

Optimization of an oral mucosa in vitro model based on cell line TR146

During the last years, the popularity of saliva has been increasing for its applicability as a diagnostic fluid. Blood biomarker molecules have to cross the blood-saliva barrier (BSB) in order to appear in saliva. The BSB consists of all oral and salivary gland epithelial barriers. Within this context, the optimization of in vitro models for mechanistic studies about the transport of molecules across the oral mucosa is an important task. Here, we describe the optimization and comprehensive characterization of a Transwell model of the oral mucosa based on the epithelial cell line TR146. Through systematic media optimization investigating 12 different set-ups, a significant increase of barrier integrity upon airlift cultivation is described here for TR146 cell layers. The distinct improvement of the paracellular barrier was described by measurements of transepithelial electrical resistance (TEER) and carboxyfluorescein permeability assays. Histological characterization supported TEER data and showed a stratified, non-keratinized multilayer of the optimized TR146 model. High-Throughput qPCR using 96 selected markers for keratinization, cornification, epithelial-mesenchymal transition, aquaporins, mucins, tight junctions, receptors, and transporter proteins was applied to comprehensively characterize the systematic optimization of the cellular model and validate against human biopsy samples. Data revealed the expression of several genes in the oral mucosa epithelium for the first time and elucidated novel regulations dependent on culture conditions. Moreover, functional activity of ABC-transporters ABCB1 and ABCC4 was shown indicating the applicability of the model for drug transport studies. In conclusion, a Transwell model of the oral mucosa epithelium was optimized suitably for transport studies.

The role of desmosomes in the ear plug formation in the bowhead whale (Balaena mysticetus)

The external acoustic meatus (EAM) of most baleen whales accumulates cellular debris annually in the lumen as whales age, forming a lamellated ear plug. The bowhead whale ear plug is formed from annually molting lining of the EAM as the entire epithelium releases at the level of the stratum basale during the spring migration. Epithelial regeneration is mostly completed by the fall migration, remaining intact for 6-7 months before being torn off the following spring. Desmosomes are integral to cell-cell adhesion with connecting desmosomal cadherins desmoglein (dsg) and desmocollin (dsc). Paraffin sections of the oral cavity and EAM lining of spring and fall adult bowhead whales, as well as the EAM of spring-caught juvenile, were immunohistochemically examined for the presence of these cadherins. In all fall specimens, both cadherins occurred in all layers except the superficial keratinous layer of the oral cavity. In spring, three different conditions existed: (a) oral cavity of spring-caught adults had reduced cadherins, with superficial fissuring in its keratinized layer and vacuolation in the upper stratum spinosum; (b) EAM of juvenile spring-caught whales displayed fissuring with accompanying reduction of both cadherins in its superficial lining; and (c) EAM lining of spring-caught adults displayed deep fissures, reduced cadherins, and absence of dsc1 in the fissuring zone. These results suggest that shedding of skin layers in mammals, whether normal molting, pathological, or the result of injury and wound repair all revolve around desmosome function. The specific role, structure, and location of these two cadherins need to be further addressed.

Molecular markers in oral lichen planus: A systematic review

Oral lichen planus (OLP) is a chronic inflammatory mucosal disease that is usually detected in 0.5–2.2% of the human population. Among these, only 0.5–2.9% of the lesions progress to carcinoma. However, there are no prognostic markers available presently to recognize the increased risk in malignant transformation of the lesions. Selected markers for cell proliferation, adhesion, apoptosis and lymphocytic infiltration were analyzed by immunohistochemistry in addition to static cytometry for DNA content. The concept linking OLP and oral squamous cell carcinoma states that chronic inflammation results in crucial DNA damage, which further progresses to development of carcinoma. Even though in the past decade, enormous information has been accumulated on malignant potential of OLP, its transformation still remains unclear. Hence, the purpose of this article was to review cellular and molecular markers to understand the pathogenesis of OLP and its progression toward malignancy.

Sequential keratinocytic differentiation and maturation in a three-dimensional model of human artificial oral mucosa

BACKGROUND AND OBJECTIVE

Oral mucosa shortage may limit or condition some clinical approaches in maxillofacial, periodontal and implant treatment. The availability of a human oral mucosa model generated by tissue engineering could help clinicians to address the lack of oral mucosa. In this work, we carried out a sequential maturation and differentiation study of the epithelial cell layer of an artificial human oral mucosa substitute based on fibrin-agarose biomaterials with fibroblasts and keratinocytes.

MATERIAL AND METHODS

Histological, immunohistochemical and gene expression analyses were carried out in artificial human oral mucosa models developed and cultured for 1, 2 and 3 wk.

RESULTS

Artificial oral mucosa models showed expression of tight junction proteins and cytokeratins from the first week of in vitro development. Mature samples of 3 wk of development subjected to air-liquid conditions showed signs of epithelial differentiation and expressed specific RNAs and proteins corresponding to adherent and gap junctions and basement lamina. Moreover, these mature samples overexpressed some desmosomal and tight junction transcripts, with gap junction components being downregulated.

CONCLUSION

These results suggest that bioengineered human oral mucosa substitutes form a well-developed epithelial layer that was very similar to human native tissues. In consequence, the epithelial layer could be fully functional in these oral mucosa substitutes, thus implying that these tissues may have clinical usefulness.

Isolation of human epidermal layers by laser capture microdissection: application to the analysis of gene expression by quantitative real-time PCR

We describe, for the first time, an efficient protocol based on laser capture microdissection (LCM) for the isolation of human epidermal layers for gene expression profiling using quantitative real-time PCR. Two areas enriched either in basal or granular layers were isolated by LCM. Skin biopsies were fixed in dry ice-cooled isopentane, cryosectioned and stained before the laser procedure. High-quality total RNA was extracted from each microdissected sample, which allowed the analysis of the spatial distribution of mRNA transcripts from 10 innate immunity-related genes within the epidermal layers. Using integrin alpha-6/integrin beta-4 and corneodesmosin/filaggrin-2 sets as gene markers for the basal and granular layers, respectively, we showed that Toll-like receptor 2, RNase 7, human beta-defensin-2 and -3, psoriasin and nucleotide-binding oligomerization domain 1 are upregulated in the suprabasal layer of normal human epidermis. Our protocol, which is based on the rapid isolation of epidermal layers, can be used to follow transcriptional processes in specific areas of the epidermis and is a very promising tool to use in the study of numerous aspects of dermatology.

A molecular study of desmosomes identifies a desmoglein isoform switch in head and neck squamous cell carcinoma

Desmosomes, the intercellular junctions that confer strong adhesion between epithelial cells, are frequently altered in malignancy. However, a comprehensive analysis of these structures has not been carried out in oral neoplasia. Oral squamous cell carcinomas (SCCs) and pre-malignant dysplasia can be sub-classified according to their in vitro replicative lifespan, where the immortal dysplasia (ID) and carcinoma (IC) subsets have p16(ink4a) and p53 dysfunction, telomerase deregulation and genetic instability and the mortal subset (MD and MC) do not. We found that the desmosomal proteins exhibit a distinct expression pattern in oral mucosa when compared with epidermis in vivo. Microarray data from a large panel of lines revealed that the transcript levels of DSG3, DSC2/3, DP, PG and PKP1 were reduced in ID and IC. Interestingly, DSG2 was up-regulated in MC. Reduction of DSG3 and up-regulation of DSG2 were found in two independent microarray datasets. Significantly, we demonstrated that reduction of DSG3 and up-regulation of DSG2 was reversible in vitro by using RNAi-mediated knockdown of DSG2 in IC cells. The remaining desmosomal proteins were largely disrupted or internalized and associated with retraction of keratin intermediate filaments in oral SCC lines. These findings suggest dysfunction and loss of desmosomal components are common events in the immortal class of oral SCC and that these events may precede overt malignancy.

Immunomapping of desmosomal and nondesmosomal adhesion molecules in healthy canine footpad, haired skin and buccal mucosal epithelia: comparison with canine pemphigus foliaceus serum immunoglobulin G staining patterns

Pemphigus foliaceus (PF) is the most common canine autoimmune skin disease. In contrast to human PF (hPF), desmoglein-1 is a minor autoantigen in the canine disease. The major autoantigen(s) of canine PF (cPF) remain(s) unknown, which limits the ability to perform mechanistic studies of lesion formation and the development of novel diagnostic and therapeutic strategies for this disease. The immunofluorescence patterns of selected desmosomal (desmoglein-1, desmoglein-3, desmocollin-1, desmocollin-3, desmoplakin-1/2, plakoglobin and plakophilin-1) and nondesmosomal adhesion proteins (E-cadherin, claudin-1, zona occludens-1 and occludin) in healthy canine footpad, haired skin and buccal mucosal epithelia were determined using hPF and pemphigus vulgaris sera and specific antibodies. The immunostaining patterns were then compared with that of indirect immunofluorescence staining with 66 cPF sera. Most cPF sera (58 of 66; 88%) exhibited positive staining along keratinocyte margins in the stratum spinosum and stratum granulosum of canine footpad. One serum contained autoantibodies binding solely to stratum granulosum keratinocytes. Concurrent intercellular fluorescence in the stratum basale was limited to seven of 66 cPF sera (11%). Only 12 of 66 cPF sera (18%) also exhibited positive IF staining of the buccal mucosa. This study confirms the immunological heterogeneity of cPF immunoglobulin G autoantibodies. Moreover, the major indirect immunofluorescence staining pattern and the inability of most cPF sera to label the buccal mucosa closely matched that of desmocollin-1. These observations warrant further investigation of desmocollin-1 as a potential major cPF autoantigen.

Transcription profiling provides insights into gene pathways involved in horn and scurs development in cattle

BACKGROUND

Two types of horns are evident in cattle - fixed horns attached to the skull and a variation called scurs, which refers to small loosely attached horns. Cattle lacking horns are referred to as polled. Although both the Poll and Scurs loci have been mapped to BTA1 and 19 respectively, the underlying genetic basis of these phenotypes is unknown, and so far, no candidate genes regulating these developmental processes have been described. This study is the first reported attempt at transcript profiling to identify genes and pathways contributing to horn and scurs development in Brahman cattle, relative to polled counterparts.

RESULTS

Expression patterns in polled, horned and scurs tissues were obtained using the Agilent 44 k bovine array. The most notable feature when comparing transcriptional profiles of developing horn tissues against polled was the down regulation of genes coding for elements of the cadherin junction as well as those involved in epidermal development. We hypothesize this as a key event involved in keratinocyte migration and subsequent horn development. In the polled-scurs comparison, the most prevalent differentially expressed transcripts code for genes involved in extracellular matrix remodelling, which were up regulated in scurs tissues relative to polled.

CONCLUSION

For this first time we describe networks of genes involved in horn and scurs development. Interestingly, we did not observe differential expression in any of the genes present on the fine mapped region of BTA1 known to contain the Poll locus.

Desmoglein 1-dependent suppression of EGFR signaling promotes epidermal differentiation and morphogenesis

Dsg1 (desmoglein 1) is a member of the cadherin family of Ca²⁺-dependent cell adhesion molecules that is first expressed in the epidermis as keratinocytes transit out of the basal layer and becomes concentrated in the uppermost cell layers of this stratified epithelium. In this study, we show that Dsg1 is not only required for maintaining epidermal tissue integrity in the superficial layers but also supports keratinocyte differentiation and suprabasal morphogenesis. Dsg1 lacking N-terminal ectodomain residues required for adhesion remained capable of promoting keratinocyte differentiation. Moreover, this capability did not depend on cytodomain interactions with the armadillo protein plakoglobin or coexpression of its companion suprabasal cadherin, Dsc1 (desmocollin 1). Instead, Dsg1 was required for suppression of epidermal growth factor receptor–Erk1/2 (extracellular signal-regulated kinase 1/2) signaling, thereby facilitating keratinocyte progression through a terminal differentiation program. In addition to serving as a rigid anchor between adjacent cells, this study implicates desmosomal cadherins as key components of a signaling axis governing epithelial morphogenesis.

Desmocollin expression in oral atrophic lichen planus correlates with clinical behavior and DNA content

BACKGROUND

Oral lichen planus (OLP) is a chronic mucocutaneous inflammatory disease, with some tendency toward malignant transformation. Markers are needed to identify the lesions at risk.

METHODS

A series of 82 biopsies from 70 patients with atrophic OLP was analyzed for desmocollin-1, E-cadherin, cyclin-dependent kinase 1 (cdk-1) and Rad-51 expression using immunohistochemistry and static DNA cytometry, with particular reference to clinical outcome.

RESULTS

Desmocollin-1 and E-cadherin expression were each detected in 24.4% (20/82) of the samples. Of the positive samples, only eight specimens expressed both desmocollin-1 and E-cadherin. Strong desmocollin-1 and E-cadherin expression was found in 8.5% and 3.7% of OLP biopsies, respectively. Desmocollin-1 expression increased the risk of dysplasia 31.8-fold (95% confidence intervals (CI) 3.6-280.9; p = 0.0001), while E-cadherin was significantly related to cancer (odds ratio (OR) = 5.13; 95% CI 3.3-8.1; p = 0.001). In univariate survival analysis, desmocollin-1 was a significant predictor of both cancer (log-rank test; p = 0.033) and dysplasia (p = 0.0001), while E-cadherin predicted the development of cancer (p = 0.0001). Neither cdk-1 nor Rad-51 had any predictive value. Importantly, desmocollin-1 retained its value as the only independent predictor of dysplasia in the multivariate (Cox) model (adjusted Hazard Ratio (HR) = 44.13; 95% CI 3.7-525.6).

CONCLUSIONS

In atrophic OLP, desmocollin-1 is a powerful predictor of an important intermediate endpoint marker (dysplasia) in the causal pathway toward oral cancer.

Delineation of diversified desmoglein distribution in stratified squamous epithelia: implications in diseases

Desmogleins play critical roles in cell adhesion and skin blistering diseases, as they are the target antigens of autoimmune antibodies and bacterial toxins. We recently cloned several novel members of the desmoglein gene family, bringing the number of desmogleins to four in the rat and human genomes and six in the mouse. Here, we have produced a monoclonal antibody to a cytoplasmic epitope of Dsg4, assessed its specificity and compared it to several existing Dsg1-3 antibodies. We also demonstrated cross-reactivity of commercially available and often used Dsg1 antibodies. Using these tools, we delineated the unique expression patterns of each desmoglein isoform in various human and mouse stratified squamous epithelia, including skin, hair, palm, and oral mucosa. Interestingly, in the epidermis, the expression of each desmoglein correlates with their gene arrangement in the cadherin locus. In human, Dsg4 was detected primarily in the granular and cornified cell layers of the epidermis, while present throughout all differentiated layers of the oral mucosa and palm, and in the matrix cells of anagen hair bulb. Similar pattern of expression for Dsg4 was observed in mouse, with the exception that it was expressed at significantly lower levels in the mouse epidermis. These results demonstrate the complexity of desmoglein gene expression and provide additional insights into the correlation between tissue expression patterns and disease phenotypes.