Depletion of Gsdma1/2/3 alleviates PMA-induced epidermal hyperplasia by inhibiting the EGFR-Stat3/Akt pathway

Homeostasis of the skin barrier is essential for maintaining normal skin function. Gasdermin A (GSDMA) is highly expressed in the skin and is associated with many skin diseases, such as melanoma and psoriasis. In mice, GSDMA is encoded by three gene homologues, namely Gsdma1, Gsdma2, and Gsdma3. Although Gsdma3 gain-of-function mutations cause hair loss and skin inflammation, Gsdma3-deficient mice show no phenotypes in skin or hair structures. To explore the physiological function of GSDMA, we generated conventional Gsdma1/2/3 knockout (KO) mice. We found that Gsdma1/2/3 KO mice showed significantly decreased epidermal hyperplasia and inflammation induced by phorbol 12-myristate 13-acetate (PMA). Furthermore, we found that the alleviation of epidermal hyperplasia depends on Gsdma1/2/3 expressed specifically in keratinocytes. Mechanistically, Gsdma1/2/3 depletion downregulated epidermal growth factor receptor (EGFR) ligands, leading to decreased EGFR-Stat3/Akt signalling. These results demonstrate that depletion of Gsdma1/2/3 alleviates PMA-induced epidermal hyperplasia partially by inhibiting the EGFR-Stat3/Akt pathway.

A New Sturgeon Herpesvirus from Juvenile Lake Sturgeon Acipenser fulvescens Displaying Epithelial Skin Lesions

Herpesvirus infections of sturgeon pose a potential threat to sturgeon culture efforts worldwide. A new epitheliotropic herpesvirus named Acipenser herpesvirus 3 (AciHV-3) was detected in hatchery-reared Lake Sturgeon Acipenser fulvescens displaying skin lesions in central Canada. The growths were discovered in the fall, reached average prevalence levels of 0.2-40% and eventually regressed. No unusual mortality was observed. The cellular changes within the lesions included epithelial hyperplasia and were reminiscent of other herpesvirus infections. The virus was not evident in lesions examined by electron microscopy. Skin tissue homogenates from symptomatic sturgeon produced atypical cytopathic effects on a primary Lake Sturgeon cell line, and next-generation sequence analysis of the DNA samples revealed the presence of an alloherpesvirus. A new genotyping PCR assay targeting the major capsid protein sequence detected AciHV-3 in symptomatic Lake Sturgeon as well as other apparently healthy sturgeon species. Bayesian inference of phylogeny reconstructed with a concatenation of five alloherpesvirus core proteins revealed a new Alloherpesviridae lineage isomorphic with a new genus. The presence of AciHV-3 homologs in cell lines and sturgeon sequence datasets, low sequence divergence among these homologs and branching patterns within the genotyping phylogeny provide preliminary evidence of an endogenous virus lifestyle established in an ancestral sturgeon.

Zerumbone attenuates the excessive proliferation of keratinocytes in psoriasis mice through regulating NLRP3/NF-κB pathway

Psoriasis is a common chronic disease, and existing treatment regimens often exhibit certain toxicities and side effects. Zerumbone (Zer) may possess therapeutic effect, and the objective of this study is to investigate the effect of Zer on psoriasis. A mouse model of psoriasis was established using imiquimod cream, and the role of Zer on the pathological alterations in psoriatic mouse skin was evaluated by psoriasis area and severity index (PASI) score; the effect of Zer on keratinocyte proliferation was evaluated via hematoxylin and eosin staining, Zen image analysis, and immunofluorescence; Immunohistochemistry and enzyme-linked immunoassay were used to evaluate the effect of Zer on tissue inflammatory responses, while malondialdehyde (MDA) and glutathione (GSH) levels were measured to elucidate the role of Zer in modulating oxidative stress; the signaling pathway regulated by Zer was evaluated by western blotting. The results demonstrated that Zer could alleviate the pathological manifestations of psoriasis, reduce PASI score, reduce skin pathological damage and epidermal hyperplasia, diminish the number of CD8+ T cells and cytokine expression levels, decrease the level of MDA and GSH and increase the expression of Nrf and HO-1. Zer was found to regulate the NLRP3/nuclear factor-kappa B (NF-κB) signaling pathway. In conclusion, Zer ameliorated the symptoms of psoriasis in mice, suppressed the keratinocyte hyperproliferation, and mitigates inflammation and oxidative stress in psoriatic skin tissue by regulating the NLRP3/NF-κB pathway.

Experimental investigation of skin toxicity after immune checkpoint inhibition in combination with radiation therapy

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy. However, structured knowledge to mitigate a patient's specific risk of developing adverse events are limited. Nevertheless, there is an exponential growth of clinical studies combining conventional therapies such as radiation therapy (RT) with ICIs. Cutaneous reactions are amongst the most common adverse events after monotherapy with either ICIs or RT. So far, little is known about inter-individual differences in the risk of developing severe tissue toxicity after the combination of RT with ICIs, and the underlying biological mechanisms are ill defined. We used experimental models of RT-induced skin injury to analyze skin toxicity after simultaneous application of ICIs. We compared different RT regimens such as fractionated or stereotactic RT with varying dose intensity. Strikingly, we found that simultaneous application of RT and ICIs did not significantly aggravate acute skin injury in two different mouse strains. Detailed examination of long-term tissue damage of the skin revealed similar signs of epidermal hyperplasia, dermal fibrosis, and adnexal atrophy. In summary, we here present the first experimental study demonstrating excellent safety profiles of concurrent treatment with RT and ICIs. These findings will help to interpret the development of adverse events of the skin after radioimmunotherapy and guide the design of new clinical trials and clinical decision making in individual cases. This article is protected by copyright. All rights reserved.

miRNAs Flowing Up and Down: The Concerto of Psoriasis

Psoriasis is a chronic immune-mediated skin disease, whose hallmarks include keratinocyte hyperproliferation and CD4⁺ T cell subsets imbalance. Dysregulated microRNAs (miRNAs) identified in psoriasis have been shown to affect keratinocyte and T cell functions, with studies on the molecular mechanisms and intrinsic relationships of the miRNAs on the way. Here, we focus on the dysregulated miRNAs that contribute to the two hallmarks of psoriasis with the miRNA target genes confirmed. We review a network, in which, upregulated miR-31/miR-203/miR-155/miR-21 and downregulated miR-99a/miR-125b facilitate the excessive proliferation and abnormal differentiation of psoriatic keratinocytes; upregulated miR-210 and downregulated miR-138 work in concert to distort CD4⁺ T cell subsets balance in psoriasis. The miRNAs exert their functions through regulating key psoriasis-associated transcription factors including NF-κB and STAT3. Whether flowing up or down, these miRNAs collaborate to promote the development and maintenance of psoriasis.

Immunobiology of Acquired Resistance to Ticks

Ticks are blood-sucking arthropods of great importance in the medical and veterinary fields worldwide. They are considered second only to mosquitos as vectors of pathogenic microorganisms that can cause serious infectious disorders, such as Lyme borreliosis and tick-borne encephalitis. Hard (Ixodid) ticks feed on host animals for several days and inject saliva together with pathogens to hosts during blood feeding. Some animal species can acquire resistance to blood-feeding by ticks after a single or repeated tick infestation, resulting in decreased weights and numbers of engorged ticks or the death of ticks in subsequent infestations. Importantly, this acquired tick resistance (ATR) can reduce the risk of pathogen transmission from pathogen-infected ticks to hosts. This is the basis for the development of tick antigen-targeted vaccines to forestall tick infestation and tick-borne diseases. Accumulation of basophils is detected in the tick re-infested skin lesion of animals showing ATR, and the ablation of basophils abolishes ATR in mice and guinea pigs, illustrating the critical role for basophils in the expression of ATR. In this review article, we provide a comprehensive overview of recent advances in our understanding of the cellular and molecular mechanisms responsible for the development and manifestation of ATR, with a particular focus on the role of basophils.

Shielding response of rodent skin to water soluble ambient air pollutants

Given the increasing levels of air pollution, understanding the direct shielding response of the skin to air pollutants as a whole under exclusion of the influence from the inside of body is important. We applied topically the water soluble ambient air pollutants to the mouse skin and observed the histological response using 0.3 mM of H₂SO₃ as a positive control. Water soluble air pollutants samples, WSAP24h and WSA72h, were collected by pumping the outdoor air into ddH₂O for 24 and 72 h respectively during two periods with different air quality index (AQI). Morphological examination showed apparent thickening of the epidermal layer in the H₂SO₃ skin section and in the sections applied with WSAP24h and WSAP72h without significant difference in the extent of epidermal hyperplasia among three groups. The cell viability assay showed no cytotoxic effect by the treatment of H₂SO₃ and WSAP24h in human skin fibroblast WS-1 cells. WSAP72h sample revealed a dose-dependent cytotoxicity to skin fibroblasts at 48 hr. The evidences indicated that the barrier function of the skin by epidermis hyperplasia could be activated by the insult of a component of air pollution, and the protection could be hold against a more complex and concentrated ambient air pollutants.

Tracking of cutaneous vascular structural changes post-UV irradiation using optical coherence tomography angiography

BACKGROUND

Ultraviolet (UV) irradiation to skin induces biological responses to protect and heal the wounded tissue. Cutaneous blood vessels play an important role in maintaining skin homeostasis, by inducing angiogenesis and vasodilation. However, the vascular dynamics in vivo, such as morphological changes over time and their depth dependency, are not fully understood.

METHODS

Ten Asian males were enrolled in this study and received UV (UVA + UVB) irradiation at two minimal erythema dose (MED) to the inner upper arm. Changes in epidermal thickness and vascular structures associated with UV irradiation were evaluated over time for 28 days by optical coherence tomography angiography (OCTA). This technique enables non-invasive visualization of three-dimensional vascular networks in human skin based on OCT assessment of skin structures with near-infrared light.

RESULTS

Notable dilation of vascular structures and increases in epidermal thickness were observed after UV irradiation. Vessel density was markedly increased from the papillary dermis to the upper reticular dermis at a depth of 200 µm. These increases in vascular density showed significant persistence even at 28 days after UV irradiation.

CONCLUSION

We visualized the vascular structural changes caused by UV irradiation and revealed that the effects of a single UV irradiation at 2 MED persisted for up to 28 days after exposure. The OCTA technique allows not only the in situ assessment of micro-vasculature in human skin but also its monitoring of vascular dynamics over time.

Classification of established atopic dermatitis in children with the in vivo imaging methods

Atopic dermatitis (AD) is a cutaneous disease resulting from a defective barrier and dysregulated immune response. The severity scoring of atopic dermatitis (SCORAD) is used to classify AD. Noninvasive imaging approaches supplementary to SCORAD were investigated. Cr:forsterite laser-based microscopy was employed to analyze endogenous third-harmonic generation (THG) and second-harmonic generation (SHG) signals from skin. Imaging parameters were compared between different AD severities. Three-dimensional reconstruction of imaged skin layers was performed. Finally, statistic models from quantitative imaging parameters were developed for predicting disease severity. Our data demonstrate that THG signal intensity of lesional skin in AD were significantly increased and was positively correlated with AD severity. Characteristic gray level co-occurrence matrix (GLCM) values were observed in more severe AD. In the 3D reconstruction video, individual dermal papilla and obvious fibrosis in the upper papillary dermis were easily identified. Our estimation models could predict the disease severity of AD patients with an accuracy of nearly 85%. The THG signal intensity and characteristic GLCM patterns are associated with AD severity and can serve as quantitative predictive parameters. Our imaging approach can be used to identify the histopathological changes of AD objectively, and to complement the SCORAD index, thus improving the accuracy of classifying AD severity.

Fucoxanthin-Containing Cream Prevents Epidermal Hyperplasia and UVB-Induced Skin Erythema in Mice

Microalgae represent a source of bio-active compounds such as carotenoids with potent anti-inflammatory and antioxidant properties. We aimed to investigate the effects of fucoxanthin (FX) in both in vitro and in vivo skin models. Firstly, its anti-inflammatory activity was evaluated in LPS-stimulated THP-1 macrophages and TNF-α-stimulated HaCaT keratinocytes, and its antioxidant activity in UVB-irradiated HaCaT cells. Next, in vitro and ex vivo permeation studies were developed to determine the most suitable formulation for in vivo FX topical application. Then, we evaluated the effects of a FX-containing cream on TPA-induced epidermal hyperplasia in mice, as well as on UVB-induced acute erythema in hairless mice. Our results confirmed the in vitro reduction of TNF-α, IL-6, ROS and LDH production. Since the permeation results showed that cream was the most favourable vehicle, FX-cream was elaborated. This formulation effectively ameliorated TPA-induced hyperplasia, by reducing skin edema, epidermal thickness, MPO activity and COX-2 expression. Moreover, FX-cream reduced UVB-induced erythema through down-regulation of COX-2 and iNOS as well as up-regulation of HO-1 protein via Nrf-2 pathway. In conclusion, FX, administered in a topical formulation, could be a novel natural adjuvant for preventing exacerbations associated with skin inflammatory pathologies as well as protecting skin against UV radiation.

Downregulated miR-187 contributes to the keratinocytes hyperproliferation in psoriasis

Psoriasis is a common chronic skin disease characterized by epidermal hyperplasia and inflammation. However, the pathogenesis of psoriasis is multifactorial and is not fully understood. MicroRNAs (miRNAs) represent a promising class of small, noncoding RNA molecules that have a large impact on cellular functions by regulating gene expression. Here we reported that microRNA-187 (miR-187), which is one of the most dynamic microRNAs identified in the deep screening miRNAs profile, is downregulated in inflammatory cytokines-stimulated keratinocytes and psoriatic skins. By luciferase activity assay and gain-of-function studies, we showed that miR-187 inhibits keratinocytes hyperproliferation by targeting CD276. Moreover, overexpression of miR-187 decreases acanthosis and reduces the disease severity in psoriasis mouse models. Taken together, the results of our study implies miR-187 as a critical factor in psoriasis pathogenesis, which could be a potent target for psoriasis treatment.

Histamine Released From Skin-Infiltrating Basophils but Not Mast Cells Is Crucial for Acquired Tick Resistance in Mice

Ticks are blood-feeding arthropods that can transmit pathogens to humans and animals, leading to serious infectious diseases such as Lyme disease. After single or multiple tick infestation, some animal species develop resistance to tick feeding, leading to reduced risk of pathogen transmission. In mice infested with larval Haemaphysalis longicornis ticks, both mast cells and basophils reportedly play key roles in the manifestation of acquired tick resistance (ATR), but it remains ill-defined how they contribute to it. Here, we investigated their products responsible for ATR. Treatment of mice with antihistamine abolished the ATR while histamine or histamine H1 receptor agonist reduced tick-feeding even in the first infestation. In accordance with these, mice deficient for histamine production showed little or no ATR, indicating the crucial role for histamine in the expression of ATR. Adoptive transfer of mast cells and basophils derived from histamine-sufficient or deficient mice to recipient mice lacking mast cells and basophils, respectively, revealed that histamine produced by basophils but not mast cells is essential for the manifestation of ATR, in contrast to the case of local and systemic anaphylaxis where mast cell-derived histamine is the major player. During the second but not first tick infestation, basophils accumulated and made a cluster, surrounding a tick mouthpart, in the epidermis whereas mast cells were scattered and localized mainly in the dermis, more distantly from a tick mouthpart. This appears to explain why basophil-derived histamine is much more effective than mast cell-derived one. Histamine-sufficient, but not -deficient mice showed the thickened epidermis at the second tick-feeding site. Taken together, histamine released from skin-infiltrating basophils rather than skin-resident mast cells plays a crucial role in the manifestation of ATR, perhaps through promotion of epidermal hyperplasia that may inhibit tick feeding.

Topical Application of Glycolipids from Isochrysis galbana Prevents Epidermal Hyperplasia in Mice

Chronic inflammatory skin diseases such as psoriasis have a significant impact on society. Currently, the major topical treatments have many side effects, making their continued use in patients difficult. Microalgae have emerged as a source of bio-active molecules such as glycolipids with potent anti-inflammatory properties. We aimed to investigate the effects of a glycolipid (MGMG-A) and a glycolipid fraction (MGDG) obtained from the microalga Isochrysis galbana on a TPA-induced epidermal hyperplasia murine model. In a first set of experiments, we examined the preventive effects of MGMG-A and MGDG dissolved in acetone on TPA-induced hyperplasia model in mice. In a second step, we performed an in vivo permeability study by using rhodamine-containing cream, ointment, or gel to determinate the formulation that preserves the skin architecture and reaches deeper. The selected formulation was assayed to ensure the stability and enhanced permeation properties of the samples in an ex vivo experiment. Finally, MGDG-containing cream was assessed in the hyperplasia murine model. The results showed that pre-treatment with acetone-dissolved glycolipids reduced skin edema, epidermal thickness, and pro-inflammatory cytokine production (TNF-α, IL-1β, IL-6, IL-17) in epidermal tissue. The in vivo and ex vivo permeation studies showed that the cream formulation had the best permeability profile. In the same way, MGDG-cream formulation showed better permeation than acetone-dissolved preparation. MGDG-cream application attenuated TPA-induced skin edema, improved histopathological features, and showed a reduction of the inflammatory cell infiltrate. In addition, this formulation inhibited epidermal expression of COX-2 in a similar way to dexamethasone. Our results suggest that an MGDG-containing cream could be an emerging therapeutic strategy for the treatment of inflammatory skin pathologies such as psoriasis.

Coccygeal Pad With an Anterior Flexed Coccyx: A Case Report

Objective: A coccygeal pad is a nodular lesion in the sacrococcygeal area. It is a rare disease characterized by corneal thickening, the proliferation of collagen bundles, and an anterior flexed coccyx. In the English literature, 42 patients have been reported. Methods: We present a young male case of a typical coccygeal pad with an anterior flexed coccyx. Results: After resection of the nodule and coccygectomy, there has been no recurrence during the 6-month postoperative follow-up. Conclusions: Plastic surgeons should recognize this as a disease to be differentiated from gluteal skin tumors.

Pseudocarcinomatous hyperplasia in anaplastic large cell lymphoma, a mimicker of poorly differentiated squamous cell carcinoma: report of a case and review of the literature

Pseudocarcinomatous hyperplasia can occasionally be observed in biopsies of CD30-positive lymphoproliferative disorders. It is important to be cognizant of this association, because epithelial hyperproliferation can overshadow large atypical lymphoid cells, leading to an erroneous diagnosis of squamous cell carcinoma (SCC) or keratoacanthoma. Herein, we present a case of anaplastic large cell lymphoma (ALCL) with pseudocarcinomatous hyperplasia simulating a poorly differentiated carcinoma and review the literature on this subject. Immunohistochemical staining with p63 helped delineate the infiltrating tongues of pseudocarcinomatous hyperplasia from the malignant infiltrate. We present this case to raise awareness of the potential for pseudocarcinomatous hyperplasia to occur in the setting of CD30+ lymphoproliferative disorders. Clinicians and dermatopathologists should consider the possibility of ALCL or lymphomatoid papulosis when examining lesions with features of inflamed SCC, especially if the tumor presents on a site or in a patient that is not typical of SCC.

Obesity exacerbates imiquimod-induced psoriasis-like epidermal hyperplasia and interleukin-17 and interleukin-22 production in mice

Psoriasis is a chronic inflammatory skin disorder that is accompanied by an imbalance between the proliferation and differentiation of keratinocytes. A number of studies have suggested an association between obesity and severe psoriasis; however, it remains to be clarified whether obesity exacerbates psoriasis. To address this unsolved question, we induced psoriasiform dermatitis in mouse models for obesity. We found that obesity exaggerated the severity of psoriasiform dermatitis induced by topical application of the Toll-like receptor (TLR) 7 agonist, imiquimod. Ear swelling and epidermal hyperplasia were more prominent in the obese mice than in the control mice. When compared to imiquimod-treated control mice, imiquimod-treated obese mice expressed higher levels of psoriasis mediators, interleukin-17A (IL-17A) and IL-22 in the skin. Food intake restriction partially abrogated enhanced ear swelling and cytokine overproduction in obese mice. Furthermore, the obesity environment and imiquimod treatment synergistically induced an IL-17A downstream molecule, regenerating islet-derived 3γ (Reg3γ), which is a critical molecule for psoriatic epidermal hyperplasia. Palmitic acid, one of the fatty acids released by subcutaneous adipocytes, increased the expression of REG3A (a human homologue of mouse Reg3γ) in both the HaCaT keratinocyte cell line and normal human keratinocytes. Taken together, these results strongly suggest that obesity exacerbates psoriasiform dermatitis in mice by upregulating IL-17A, IL-22 and Reg3γ.

Immunological and histological evaluation of clinical samples from psoriasis patients treated with anti-CD6 itolizumab

Psoriasis is a chronic inflammatory disease with a prevalence of approximately 2-3% in the general population. The majority of diagnosed patients have plaque psoriasis, and about 20% have moderate-to-severe disease. Itolizumab, a new monoclonal antibody specific for the CD6 molecule mainly expressed on T lymphocytes, has demonstrated to inhibit in vitro ligand-induced proliferation and pro-inflammatory cytokine production. We assessed the immunological and histopathological effect of the antibody using clinical samples taken from 26 patients with moderate-to-severe psoriasis included in a clinical trial. The precursor frequency of lymphocytes activated with anti-CD2/CD3/CD28 beads, as well as the number of interferon (IFN)-γ-secreting T cells after stimulation, were measured at different time points of the study. Serum cytokine levels and anti-idiotypic antibody response to itolizumab were also evaluated. Additionally, lymphocyte infiltration and epidermis hyperplasia were studied in five patients. A significant reduction in T cell proliferation capacity and number of IFN-γ-producing T cells was found in treated patients. Serum levels of interleukin-6, tumor necrosis factor and IFN-γ showed an overall trend toward reduction. No anti-idiotypic antibody response was detected. A significant reduction in the epidermis hyperplasia was observed in analyzed patients. These results support the relevance of the CD6 molecule as a therapeutic target for the treatment of this disease.