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Mast cells (MCs) are tissue-resident hematopoietic cells intensely studied for their role as effectors in allergic immune responses. Yolk sac-derived embryonic MCs first populate tissues and are later replaced by definitive MCs. We show that definitive MC progenitors expand locally in skin and form clonal colonies that cover stable territories. In MC-deficient skin, colonies grow by proliferation of MCs at the border of the clonal territory. Clonal growth ceases at common borders of neighboring colonies. In steady state, colony self-renewal is independent of bone marrow contribution, and the clonal architecture remains fixed if not disturbed by skin inflammation. Inflammatory cues increase MC density setpoint, stimulating the influx of new progenitors from the bone marrow as well as proliferation of skin-resident cells. The expanding new arrivals disrespect territories of preexisting MC clones. We conclude that during a limited window early in development, definitive MC precursors efficiently enter the skin, expand, and self-maintain, occupying stable territories. In adulthood, circulating progenitors, excluded from steady-state skin, are recruited only into inflamed skin where they clonally expand alongside proliferating skin-resident MCs, disorganizing the original architecture of clonal territories., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Fibronectin (FN) circulating in the blood and produced by cells provides the basis of the extracellular matrix (ECM) formed in healing acute wounds. The time-dependent deposition of FN by macrophages, its synthesis by fibroblasts and myofibroblasts, and later degradation in the remodeled granulation tissue are a prerequisite for successful healing of wounds. However, the pattern of FN expression and deposition in skin lesions is disturbed. The degradation of the ECM components including FN in varicose veins prevails over ECM synthesis and deposition. FN is inconspicuous in the fibrotic lesions in lipodermatosclerosis, while tenascin-C containing FN-like peptide sequences are prominent. FN is produced in large amounts by fibroblasts at the edge of venous ulcers but FN deposition at the wound bed is impaired. Both the proteolytic environment in the wounds and the changed function of the ulcer fibroblasts may be responsible for the poor healing of venous ulcers. The aim of this review is to describe the current knowledge of FN pathophysiology in chronic venous diseases. In view of the fact that FN plays a crucial role in organizing the ECM, further research focused on FN metabolism in venous diseases may bring results applicable to the treatment of the diseases.

The physical, psychological and financial burden of skin disease in low- to middle-income countries, where access to skincare is limited, is poorly understood. A group that we know very little about in this regard are refugees. There are limited data on the range of skin diseases and skincare needs of this group. To better understand the skincare needs of the displaced Rohingya population residing in the Kutupalong refugee camp, Bangladesh, we collected data on demographics, living conditions and range of dermatoses. In the 380 patients assessed, fungal skin infections, predominantly dermatophytes, were by far the most common skin disease seen (n = 215), followed by dermatitis (n = 81). Skin disease can be the presenting feature in many systemic conditions and may cause significant secondary complications itself. Developing a better understanding of the skincare needs of the refugee population is essential for future healthcare planning for this vulnerable group., (© 2020 British Association of Dermatologists.)

We investigated how loss of TSG-6 affects wound closure and skin inflammation. TSG-6 has several known biological functions, including the enzymatic transfer of heavy-chain proteins from inter-α-trypsin inhibitor to hyaluronan to form heavy-chain protein-hyaluronan complexes. TSG-6 and heavy-chain protein-hyaluronan are constitutively expressed in normal skin and increase post-wounding but are completely absent in TSG-6-null mice. Wound closure rates are significantly delayed in TSG-6-null mice relative to wildtype mice. Neutrophil recruitment is delayed in early wounds (12 hours and day 1), whereas late wounds (day 7) show elevated neutrophil accumulation. In addition, granulation phase resolution is delayed, with persistent blood vessels and reduced dermal collagen at 10 days. The proinflammatory cytokine TNFα is elevated >3-fold in unwounded TSG-6-null skin and increases further after wounding (from 12 hours to 7 days) before returning to baseline by day 10. Other cytokines examined, such as IL-6, IL-10, and monocyte chemotactic protein-1, showed no consistent differences. Reintroduction of TSG-6 into TSG-6-null wounds rescues both the delay in wound closure and the aberrant neutrophil phenotype. In summary, our study indicates that TSG-6 plays an important role in regulating wound closure and inflammation during cutaneous wound repair., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

History: A female patient aged 57 presented at the emergency room with painful skin lesions after repeated gardening days. Bullae and striate erythema were ovserved in light exposed areas. The patient was transferred to the Dermatology Department at the University hospital Jena, Germany., Findings and Diagnosis: Blood test showed raised levels of inflammation parameters. The general body examination showed no abnormalities. Dermatits bullosa pratensis (grass dermatitis), was diagnosed, based on the patient case history, the examination results and the typical skin lesions., Therapy and Course: Treatment with intravenous corticosteroids, followed by topical steroids and sterile punctures of blisters was prescribed., Conclusions: Dermatits bullosa pratensis, is a skin condition appearing during the summer season in Germany. It belongs to the photo phytotoxic dermatitis types and is induced by phytochemicals in combination with UV-light. It is therefore important to take appropriate skin protective safety measures when touching plant containing phytochemicals in sunlight. In this way dermatitis bullosa pratensis can be easily avoided., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

cFLIP is required for epidermal integrity and skin inflammation silencing via protection from TNF-induced keratinocyte apoptosis. Here, we generated and analyzed cFLIP epidermal KO mice with additional TNF deficiency. Intriguingly, the ablation of TNF rescued the pathological phenotype of epidermal cFLIP KO from characteristic weight loss and increased mortality. Moreover, the lack of TNF in these animals strongly reduced and delayed the epidermal hyperkeratosis and the increased apoptosis in keratinocytes. Our data demonstrate that TNF signaling in cFLIP-deficient keratinocytes is the critical factor for the regulation of skin inflammation via modulated cytokine and chemokine expression and, thus, the attraction of immune cells. Our data suggest that autocrine TNF loop activation upon cFLIP deletion is dispensable for T cells, but is critical for neutrophil attraction. Our findings provide evidence for a negative regulatory role of cFLIP for TNF-dependent apoptosis and partially for epidermal inflammation. However, alternative signaling pathways may contribute to the development of the dramatic skin disease upon cFLIP deletion. Our data warrant future studies of the regulatory mechanism controlling the development of skin disease upon cFLIP deficiency and the role of cFLIP/TNF in a number of inflammatory skin diseases, including toxic epidermal necrolysis (TEN).

A 65-year-old man with acute myeloid leukemia 6 was treated by bone marrow allograft, developed a systemic classic chronic graft versus host disease with hepatic, rheumatologic, ophthalmic, and muco-cutaneous involvement. He received systemic corticosteroid, ruxolitinib and extracorporeal photopheresis which resulted in complete remission. During follow-up the patient presented with viral cutaneous warts on his neck and submandibular area. After various subsequent topical treatments, he developed localized cutaneous GVHD without any general GVHD reactivation symptoms. To the best of our knowledge, there has been no description in the literature of a graft versus host disease developing after local immunomodulatory or cytotoxic treatments. Topical therapies are commonly used by dermatologists for superficial skin cancers and some viral skin lesions, in high risk populations such as organ transplant patients with regular follow-up.Practitioners should be made aware of a possible localized cutaneous GVHD reactivation induced by Koebner phenomenon after local therapy.

A 12-y-old spayed female Schipperke dog with a previous diagnosis of inflammatory bowel disease was presented with a 2-mo history of severe colitis. The patient's condition progressed to hepatopathy, pneumonia, and dermatitis following management with prednisolone and dexamethasone sodium phosphate. Colonic biopsies identified severe necrosuppurative colitis with free and intracellular parasitic zoites. Postmortem examination confirmed extensive chronic-active ulcerative colitis, severe acute necrotizing hepatitis and splenitis, interstitial pneumonia, ulcerative dermatitis, myelitis (bone marrow), and mild meningoencephalitis with variable numbers of intracellular and extracellular protozoal zoites. PCR on samples of fresh colon was positive for Neospora caninum . Immunohistochemistry identified N. caninum tachyzoites in sections of colon, and a single tissue cyst in sections of brain. Administration of immunosuppressive drugs may have allowed systemic dissemination of Neospora from the intestinal tract.

Keratinocytes and skin immune cells are actively metabolizing nutrients present in their microenvironment. This is particularly important in common chronic inflammatory skin diseases such as psoriasis and atopic dermatitis, characterized by hyperproliferation of keratinocytes and expansion of inflammatory cells, thus suggesting increased cell nutritional requirements. Proliferating inflammatory cells and keratinocytes express high levels of glucose transporter (GLUT)1, l-type amino acid transporter (LAT)1, and cationic amino acid transporters (CATs). Main metabolic regulators such as hypoxia-inducible factor (HIF)-1α, MYC, and mechanistic target of rapamycin (mTOR) control immune cell activation, proliferation, and cytokine release. Here, we provide an updated perspective regarding the potential role of nutrient transporters and metabolic pathways that could be common to immune cells and keratinocytes, to control psoriasis and atopic dermatitis., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Hematophagous vectors lacerate host skin and capillaries to acquire a blood meal, resulting in leakage of red blood cells (RBCs) and inflammation. Here, we show that heme oxygenase-1 (HO-1), a pleiotropic cytoprotective isoenzyme that mitigates heme-mediated tissue damage, is induced after bites of sand flies, mosquitoes, and ticks. Further, we demonstrate that erythrophagocytosis by macrophages, including a skin-residing CD163 + CD91 + professional iron-recycling subpopulation, produces HO-1 after bites. Importantly, we establish that global deletion or transient inhibition of HO-1 in mice increases inflammation and pathology following Leishmania-infected sand fly bites without affecting parasite number, whereas CO, an end product of the HO-1 enzymatic reaction, suppresses skin inflammation. This indicates that HO-1 induction by blood-feeding sand flies promotes tolerance to Leishmania infection. Collectively, our data demonstrate that HO-1 induction through erythrophagocytosis is a universal mechanism that regulates skin inflammation following blood feeding by arthropods, thus promoting early-stage disease tolerance to vector-borne pathogens., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Lichenoid granulomatous dermatitis (LGD) is a histopathologic pattern with a band-like lymphocytic infiltrate, typical of lichenoid dermatitis, combined with dermal histiocytes and granulomatous inflammation. Prior reports have described cases of LGD caused by non-tuberculous mycobacteria, with evidence of intralesional acid-fast bacilli or mycobacterial DNA. Herein, we report a patient with pulmonary and extrapulmonary Mycobacterium tuberculosis infection who developed LGD. No evidence of M. tuberculosis was detected within the cutaneous lesions, suggesting a potential delayed-type hypersensitivity reaction to tuberculosis., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Metformin, a potent AMPK activator is the most commonly used drug for diabetes. According to recent reports, metformin lowers the risk of diabetic complications and inflammatory diseases. We found the expression levels of AMPK subunits including PRKAA1, PRKAA2, PRKAB1 and PRKAB2 are decreased in skin biopsies of dermatitis patients from multiple datasets. Interestingly, metformin treatment ameliorates dermatitis symptom in animal model of dermatitis using O-tetradecanoylphorbol-13-acetate (TPA). Especially, the levels of epidermis and dermis thickness were decreased by metformin. We found NFκB activity as well as of gene expression associated with collagen synthesis are attenuated by metformin treatment. These results suggest that metformin treatment alleviates animal model of dermatitis.

The histology of erythema (chronicum) migrans (ECM) is classically described as a nonspecific perivascular infiltrate with a variable number of plasma cells and eosinophils. However, deviations from this pattern were described, such as focal interface changes or spongiosis, potentially posing a clinicopathological challenge. In this study, cases submitted with a serologically confirmed, clinically unequivocal, or highly suspicious diagnosis of ECM/Lyme disease between January 01, 2016, and September 01, 2018, were retrieved from the electronic database system and reviewed to delineate the histopathologic features of ECM. The series consisted of 14 cases. A superficial perivascular lymphocytic infiltrate was noted in all biopsies, accompanied by a deep and/or interstitial inflammatory infiltrate in 9 cases (64%). The inflammation ranged from relatively sparse to dense and prominent. At least focal interface changes were noted in 12 biopsies (86%). Eosinophils and plasma cells were noted in 7 (50%) and 10 (71%) cases, respectively. From a histologic standpoint, ECM is a protean entity and may manifest with a variable density of perivascular and/or interstitial lymphocytic infiltrate admixed with eosinophils and/or plasma cells and accompanied by focal interface dermatitis. Within the appropriate clinical context, ECM should be considered in the differential diagnosis of focal interface and/or sparse perivascular dermatitis.

Potassium iodide (KI), initially derived from seaweed in the early 19th century, is used for treating sporotrichosis in dermatological practice. KI has also been used to treat several noninfectious inflammatory skin diseases. However, the mechanisms underlying the improvement in such skin diseases remain unknown, and KI is not used widely. Thus, although KI is an old drug, physicians may not prescribe it frequently because they lack knowledge about it. Although KI is very inexpensive and causes few side effects, it has been superseded by new powerful and expensive drugs, such as biological agents. We applied 3% KI topically to areas of inflammation induced by SDS in mice. The levels of IL-1 and TNF-α gene expression were reduced, whereas that of IL-10 gene expression was increased. Small interfering RNA that was designed to reduce IL-10 gene expression levels was injected into the same mice, and the anti-inflammatory effects of KI were not observed. Thus, the pharmacologic action of KI is based on its anti-inflammatory effects caused by the increase in IL-10 levels. This information would increase dermatologists' awareness of KI as an efficacious and cost-effective treatment., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Psoriasis is one of the most common immune-mediated chronic inflammatory skin diseases. However, little is known about the molecular mechanism underlying the immunological circuits that maintain innate and adaptive immune responses in established psoriasis. In this study, we found that the Pellino1 (Peli1) ubiquitin E3 ligase is activated by innate pattern-recognition receptors (PRRs), such as Toll-like receptors (TLRs), and is highly upregulated in human psoriatic skin lesions and murine psoriasis-like models. Increased Peli1 expression is strongly correlated with the immunopathogenesis of psoriasis by activating hyperproliferation of keratinocytes in the S and G2/M phases of the cell cycle and promoting chronic skin inflammation. Furthermore, Peli1-induced psoriasis-like lesions showed significant changes in the expression levels of several T helper 17 (Th17)-related cytokines, such as IL-17a, IL-21, IL-22, IL-23, and IL-24, indicating that overexpression of Peli1 resulted in the sequential engagement of the Th17 cell response. However, the overexpression of Peli1 in T cells was insufficient to trigger psoriasis, while T cells were indispensable for disease manifestation. In summary, our findings demonstrate that Peli1 is a critical cell cycle activator of innate immunity, which subsequently links Th17 cell immune responses to the psoriatic microenvironment.

Skin diseases bring great psychological and physical impacts on patients, however, a considerable number of skin diseases still lack effective treatments, such as psoriasis, systemic lupus erythematosus, melanoma and so on. Receptor-interacting serine threonine kinase 1 (RIPK1) plays an important role in cell death, especially necroptosis, associated with inflammation and tumor. As many molecules modulate the ubiquitination of RIPK1, disruption of this checkpoint can lead to skin diseases, which can be ameliorated by RIPK1 inhibitors. This review will focus on the molecular mechanism of RIPK1 activation in inflammation as well as the current knowledges on the contribution of RIPK1 in skin diseases., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2020 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

Skin, as the major organ of a human body, is constantly exposed to PM 2.5 stimulation, which may exert specific toxic influences on the physiology of skin. This study aims to investigate the effect of PM 2.5 on the formation of inflammasomes in skin cells and to explore the potential mechanism linking PM 2.5 and skin inflammation. Changes in mRNA and protein levels of inflammasome-related genes were detected by real-time PCR and western blot in human immortalized epidermal cells (HaCaT) treated with PM 2.5 at multiple concentrations for 24 hours. The expression of NLRP1 was increased significantly both in mRNA and protein levels after PM 2.5 exposure while the elevated secretory protein level of IL-1β in cell culture was detected by ELISA, which is one of the main downstream factors of NLRP1. In addition, the upregulation of NLRP1 and IL-1β could be reversed by NF-κB inhibitor indicating that PM 2.5 may promote NLRP1 expression through activating NF-κB pathway. Furthermore, high ROS level was also found in cells treated with PM 2.5 and inhibition of ROS could also reverse NK-κB production stimulated by PM 2.5 that means ROS is involved in this skin inflammation process., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: There are conflicting reports on the association between interface dermatitis and hepatic involvement in DRESS., Methods: A cross-sectional analysis of the clinical and the histopathologic features of DRESS was performed to study the association between the histopathology of the skin rash and hepatic involvement., Results: The clinical and the histopathologic findings were evaluated in 40 cases of DRESS. Thirty patients (75%) had a hepatic involvement. Thirty (75%) biopsy specimens showed a combination of different inflammatory patterns. The interface dermatitis was noted in 24 specimens (60%). Twenty-one patients with the interface dermatitis had a hepatic involvement (P = .04)., Conclusions: The skin rash of DRESS often shows the coexistence of different inflammatory patterns. The interface dermatitis showed a statistically significant association with the hepatic involvement in DRESS., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

This case series discusses 3 patients with long-standing eczematous or psoriasiform dermatitis, demonstrated by multiple biopsies. Following off-label treatment with dupilumab, all 3 patients had clinical expansion of disease, with histopathologic features consistent with cutaneous T-cell lymphoma (CTCL) on subsequent biopsy. We postulate that this expansion likely was secondary to an exacerbation of extant CTCL following exposure to dupilumab. A proposed mechanism of promotion of CTCL is based on the functional increase in IL-13 available for binding at the upregulated IL-13 receptor (IL-13R) α2 site on cells, following blockade of the α1 receptor with dupilumab. This progression merits further investigation.

Nuclear inhibitor of protein phosphatase 1 (NIPP1) is a ubiquitously expressed nuclear protein that regulates functions of protein serine/threonine phosphatase-1 in cell proliferation and lineage specification. The role of NIPP1 in tissue homeostasis is not fully understood. This study shows that the selective deletion of NIPP1 in mouse epidermis resulted in epidermal hyperproliferation, a reduced adherence of basal keratinocytes, and a gradual decrease in the stemness of hair follicle stem cells, culminating in hair loss. This complex phenotype was associated with chronic sterile skin inflammation and could be partially rescued by dexamethasone treatment. NIPP1-deficient keratinocytes massively expressed proinflammatory chemokines and immunomodulatory proteins in a cell-autonomous manner. Chemokines subsequently induced the recruitment and activation of immune cells, in particular conventional dendritic cells and Langerhans cells, accounting for the chronic inflammation phenotype. The data identifies NIPP1 as a key regulator of epidermal homeostasis and as a potential target for the treatment of inflammatory skin diseases., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

BACKGROUND Obesity is one of the leading causes of preventable death worldwide. Due to its increasing incidence and the difficulty in reducing its morbidity and mortality using nonsurgical methods, the demand for bariatric surgery has risen in recent times. Sleeve gastrectomy is one of the most common types of bariatric surgery, and like any other surgery, it carries a series of risks. CASE REPORT Although complications such as gastrointestinal leaks are widely reported, there is limited literature available on cutaneous complications. Here, we report 4 cases of patients showing a peculiar skin rash 2-4 weeks following sleeve gastrectomy. We also discuss some of the mechanisms that may underlie this correlation. CONCLUSIONS There is a need for further epidemiological studies to determine the prevalence of this rash. Further studies are also needed to determine the exact etiology of this rash.

Psoriasis is a common, chronic multifactorial inflammatory skin disease with both genetic and environmental components. A number of studies have suggested that psoriasis episodes are often preceded by stressful life events. Nevertheless, the underline mechanisms of stress in psoriasis remain unexplored. To address this question, we established an emotional stress mouse model induced by empty bottle stimulation, and applied imiquimod (IMQ), a ligand of TLR7/8 and effective potent immune activator, on the dorsal skin to induce psoriasis-like lesions. We found that empty bottles induced emotional stress exaggerated and prolonged psoriasiform dermatitis, which appeared as more prominent epidermal hyperplasia in the emotional stress mice compared with the control mice. Higher mRNA expression of Il-1β, Il-17a, and Il-22, as well as higher secretion of IL-1β, IL-12p40, IL-17, and IL-22 were observed in the skin lesion of emotional stress mice. The emotional stress condition and IMQ treatment synergistically led to higher expression levels of neurotransmitters and their receptors in the skin, especially substance P (SP), we also found that SP could stimulate DCs to secrete more IL-23p40 in vitro. In addition, NK-1R antagonist partially abrogated enhanced epidermal thickness and the level of neurotransmitters in emotional stress mice. Taken together, these results indicate that stress exacerbates and prolongs psoriasiform dermatitis in mice by up-regulating IL-1β and IL-23p40, which were related to local DCs stimulated by abnormal SP., (©2020 Society for Leukocyte Biology.)

The exact microscopic diagnosis of inflammatory skin diseases requires the linking of histopathological findings with clinical features. This is not easy when skin biopsies are rarely assessed and the terminology of dermatopathology and dermatology is itself unfamiliar.The infiltrates of almost all inflammatory skin diseases tend to show eight specific patterns in high magnification. By further classifying according to architectural and cytological features, a specific diagnosis can be made in most cases. At the same time, clinically suspected diagnoses are simply excluded or greatly reduced in number. This procedure, starting with the overview magnification and the recognition of clearly defined histomorphological features, corresponds to an algorithm.Another algorithmic approach uses histomorphological changes under high magnification. Here, "nonspecific" findings are added to the pattern analysis as a diagnostic vehicle.Occasionally, inflammatory skin diseases cannot be assessed conclusively with current modern methods. Such pathology reports should be written descriptively and possible differential diagnoses should be mentioned as notes. The report should be written in a language understandable to the clinician.Artificial intelligence, with its ability to transform and integrate extensive clinical as well as image data, will play an important role in the future of decision making, diagnosing, and personalizing medicine. In the field of pathology, it could be seen as a second opinion. It is important that physicians always contribute their opinion where important algorithmic decisions are made, such as in algorithm design, data quality, interpretation, action, and feedback.

Ichthyoses are hereditary cornification disorders that occur in isolation (nonsyndromic) or with associated internal diseases (syndromic) and can lead to life-threatening complications. The identification of the genetic causes has led to an understanding of the molecular mechanisms, but also to reclassification. The pathological changes in skin biopsies were also more precisely characterized. Certain histological patterns could be defined, which are based on the defects of epidermal differentiation but also on the inflammatory pattern. Complementary histo- and immunohistochemical methods sometimes allow a precise diagnosis, or at least a limitation of the differential diagnoses.

We report the case of a 13-year-old young lady with a one year reccuring bullous dermatitis history for which the diagnostic hypothesis of dermatitis arterfacta was made. This hypothesis was made by the pathologist, without it being suggested by the dermatologist, after observing singular histological lesions coresponding to a cutaneous blister associated with epidermic necrosis with multinucleated keratinocytes. When dermatitis artefacta is suspected, a biopsy is usually conducted to rule out differential diagnosis such as auto-immmune dermatitis when there is a blister. Confession from patients is rarely obtained. Therefore, having positive histogical clues for dermatitis artefacta would be of a great use to help making the diagnosis in difficult cases., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Kallikrein-related peptidase 6 (KLK6) is a secreted serine protease hypothesized to promote inflammation via cleavage of protease-activated receptor 1 (PAR1) and PAR2. KLK6 levels are elevated in multiple inflammatory and autoimmune conditions, but no definitive role in pathogenesis has been established. Here, we show that skin-targeted overexpression of KLK6 causes generalized, severe psoriasiform dermatitis with spontaneous development of debilitating psoriatic arthritis-like joint disease. The psoriatic skin and joint phenotypes are reversed by normalization of skin KLK6 levels and attenuated following genetic elimination of PAR1 but not PAR2. Conservation of this regulatory pathway was confirmed in human psoriasis using vorapaxar, an FDA-approved PAR1 antagonist, on explanted lesional skin from patients with psoriasis. Beyond defining a critical role for KLK6/PAR1 signaling in promoting psoriasis, our results demonstrate that KLK6/PAR1-mediated inflammation in the skin alone is sufficient to drive inflammatory joint disease. Further, we identify PAR1 as a promising cytokine-independent target in therapy of psoriasis and psoriatic arthritis.

Trichobilharzia regenti (Schistosomatidae) percutaneously infects birds and mammals and invades their central nervous system (CNS). Here, we characterized the peripheral immune response of infected mice and showed how it was influenced by the parasite-induced inflammation in the skin and the CNS. As revealed by flow cytometry, T cells expanded in the spleen and the CNS-draining lymph nodes 7-14 days post-infection. Both T-bet+ and GATA-3+ T cells were markedly elevated suggesting a mixed type 1/2 immune response. However, it dropped after 7 dpi most likely being unaffected by the neuroinflammation. Splenocytes from infected mice produced a high amount of IFN-γ and, to a lesser extent, IL-10, IL-4 and IL-17 after in vitro stimulation by cercarial homogenate. Nevertheless, it had only a limited capacity to alter the maturation status of bone marrow-derived dendritic cells (BMDCs), contrary to the recombinant T. regenti cathepsin B2, which also strongly augmented expression of Ccl5, Cxcl10, Il12a, Il33 and Il10 by BMDCs. Taken together, mice infected with T. regenti developed the mixed type 1/2 immune response, which was driven by the early skin inflammation rather than the late neuroinflammation. Parasite peptidases might play an active role in triggering the host immune response., (© 2020 John Wiley & Sons Ltd.)

Receptor interacting protein kinase 1 (RIP1) is a critical effector of inflammatory responses and cell death activation. Cell death pathways regulated by RIP1 include caspase-dependent apoptosis and caspase-independent necroptosis. The kinase activity of RIP1 has been associated with a number of inflammatory, neurodegenerative, and oncogenic diseases. In this study, we use the RIP1 kinase inhibitor GNE684 to demonstrate that RIP1 inhibition can effectively block skin inflammation and immune cell infiltrates in livers of Sharpin mutant (Cpdm; chronic proliferative dermatitis) mice in an interventional setting, after disease onset. On the other hand, genetic inactivation of RIP1 (RIP1 KD) or ablation of RIP3 (RIP3 KO) or MLKL (MLKL KO) did not affect testicular pathology of aging male mice. Likewise, infection with vaccinia virus or with mouse gammaherpesvirus MHV68 resulted in similar viral clearance in wild-type, RIP1 KD, and RIP3 KO mice. In summary, this study highlights the benefits of inhibiting RIP1 in skin inflammation, as opposed to its lack of relevance for testicular longevity and the response to certain viral infections., (© 2020 The Authors. Journal of Leukocyte Biology published by Wiley Periodicals, Inc. on behalf of Society for Leukocyte Biology.)

Background: Photobiomodulation (PBM) has shown efficacy in preventing and treating cancer therapy-induced mucositis and dermatitis. However, there is contradictory information regarding the effect of PBM on (pre)malignant cells, which has led to questions regarding the safety of this technique. We address this issue using an orthotopic mouse model (Cal-33) with human squamous cell carcinoma of the oral cavity., Methods: Mice with actively growing orthotopic Cal-33 head and neck carcinoma tumors were divided into 4 groups: control, PBM only, radiation therapy (RT) only, and PBM + RT. We performed three experiments: (1) PBM at 660 nm, 18.4 J/cm 2 , and 5 RT × 4 Gy doses delivered daily; (2) PBM at 660 nm, 18.4 J/cm 2 , and 1 × 15 Gy RT; and (3) PBM at 660 nm + 850 nm, 45 mW/cm 2 , 3.4 J/cm 2 , and 1 × 15 Gy RT. Mice were weighed daily and tumor volumes were evaluated by IVIS. Survival time was also evaluated., Results: Animals treated with RT survived significantly longer and had significantly smaller tumor volume when compared with the control and PBM-only treatment groups. No significant differences were noted between the RT alone and PBM + RT groups in any of the experiments., Conclusion: Our results suggest that PBM at the utilized parameters does not provide protection to the tumor from the killing effects of RT.

Pododermatitis is an important cause of morbidity and mortality in flamingos under human care; management and treatment options vary widely based on subjective assessment from veterinarians or animal care staff (ACS). The objective of this study was to evaluate the agreement of pododermatitis severity scores assigned by veterinarians, ACS, and veterinary students when given a standardized rubric. Twenty-four greater flamingos ( Phoenicopterus roseus ) from a single zoo-managed flock were evaluated over time for pododermatitis. The individual feet of each bird were imaged, blinded, randomized, and scored for hyperkeratosis, fissures, nodules, papillomatous growth, and overall subjective score by seven evaluators (three veterinary specialists, two ACS, and two veterinary students) using a previously established flamingo pododermatitis scoring rubric. Interindividual reliability between evaluators and intraindividual agreement among specialists was determined. Reliable interindividual agreement was seen for fissures (Krippendorff's α [KA] = 0.807) between all seven evaluators, whereas the other individual lesions had very low reliability. Between the specialists, fissures had low interindividual reliability (KA = 0.782). Two specialists had strong intraindividual agreement for fissure score and one specialist had strong intraindividual agreement for overall subjective score (Cohen's κ [CK] 0.8-0.9, P < 0.01). Hyperkeratosis, papillomatous growth, nodules, and overall subjective score had low to moderate inter- and intraindividual reliability or agreement (KA, 0.06-0.49; CK, 0.02-0.8). In conclusion, the current scoring method for flamingo pododermatitis does not supply a reliable method for tracking foot health based on images alone across timepoints, except for fissures. Further analysis of the scoring system being used during a physical examination is warranted.

The assessment of bird-based welfare indicators plays an important role in the evaluation of bird welfare. The aim of the study was to histologically validate a visual scoring system for hock burn in broilers and to detect threshold values of a visual score to define welfare-relevant alterations in terms of mild lesions or ulcers of the hock. We collected 200 hocks of 39- to 42-day-old Ross 308 broilers after the slaughter process. Each hock was scored visually ("macro scores" 0-4) and evaluated histologically ("micro scores" 0-3), with high scores representing more severe lesions. Although we found a tendency for higher micro scores with increasing macro scores, an exact allocation of macro to micro scores was not possible. For example, macro score 1 could represent micro scores 1, 2 and 3, whereas macro scores 3 and 4 always represented micro score 3 (ulcer). The conditional probability of certain micro scores for given macro scores was estimated using a multinomial logistic regression model. Ulcer showed the highest probability at macro score 1, whereas mild lesions were not found to have an estimated highest probability at any macro score. The depth of inflammation of hock burn lesions increased with increasing macro scores up to macro score 3 with an average depth of 1019 µm. Visually more severe and deeper lesions were also histologically rated with higher scores. Thus, considering limitations, the herein validated macroscopic assessment scheme for hock burn allows an estimation of histological alterations in hocks of broilers. RESEARCH HIGHLIGHTS Histological validation of a visual assessment scheme for hock burn in broilers.Tendency for higher micro scores with increasing macro scores.Estimation of histological score via macro score possible with limitations.Histological depth of inflammation increased with an increasing macro score.

Most systemic lupus erythematosus (SLE) patients are photosensitive and ultraviolet B light (UVB) exposure worsens cutaneous disease and precipitates systemic flares of disease. The pathogenic link between skin disease and systemic exacerbations in SLE remains elusive. In an acute model of UVB-triggered inflammation, we observed that a single UV exposure triggered a striking IFN-I signature not only in the skin, but also in the blood and kidneys. The early IFN-I signature was significantly higher in female compared to male mice. The early IFN-I response in the skin was almost entirely, and in the blood partly, dependent on the presence of cGAS, as was skin inflammatory cell infiltration. Inhibition of cGAMP hydrolysis augmented the UVB-triggered IFN-I response. UVB skin exposure leads to cGAS-activation and both local and systemic IFN-I signature and could contribute to acute flares of disease in susceptible subjects such as patients with SLE.

Most monogenic disorders have a primary clinical presentation. Inherited ISG15 deficiency, however, has manifested with two distinct presentations to date: susceptibility to mycobacterial disease and intracranial calcifications from hypomorphic interferon-II (IFN-II) production and excessive IFN-I response, respectively. Accordingly, these patients were managed for their infectious and neurologic complications. Herein, we describe five new patients with six novel ISG15 mutations presenting with skin lesions who were managed for dermatologic disease. Cellularly, we denote striking specificity to the IFN-I response, which was previously assumed to be universal. In peripheral blood, myeloid cells display the most robust IFN-I signatures. In the affected skin, IFN-I signaling is observed in the keratinocytes of the epidermis, endothelia, and the monocytes and macrophages of the dermis. These findings define the specific cells causing circulating and dermatologic inflammation and expand the clinical spectrum of ISG15 deficiency to dermatologic presentations as a third phenotype co-dominant to the infectious and neurologic manifestations., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

: Adipose tissue (AT) is the largest endocrine organ, producing bioactive products called adipocytokines, which regulate several metabolic pathways, especially in inflammatory conditions. On the other hand, there is evidence that chronic inflammatory skin disease is closely associated with vascular sclerotic changes, cardiomegaly, and severe systemic amyloidosis in multiple organs. In psoriasis, a common chronic intractable inflammatory skin disease, several studies have shown that adipokine levels are associated with disease severity. Chronic skin disease is also associated with metabolic syndrome, including abnormal tissue remodeling; however, the mechanism is still unclear. We addressed this problem using keratin 14-specific caspase-1 overexpressing transgenic (KCASP1Tg) mice with severe erosive dermatitis from 8 weeks of age, followed by re-epithelization. The whole body and gonadal white AT (GWAT) weights were decreased. Each adipocyte was large in number, small in size and irregularly shaped; abundant inflammatory cells, including activated CD4+ or CD8+ T cells and toll-like receptor 4/CD11b-positive activated monocytes, infiltrated into the GWAT. We assumed that inflammatory cytokine production in skin lesions was the key factor for this lymphocyte/monocyte activation and AT dysregulation. We tested our hypothesis that the AT in a mouse dermatitis model shows an impaired thermogenesis ability due to systemic inflammation. After exposure to 4 °C, the mRNA expression of the thermogenic gene uncoupling protein 1 in adipocytes was elevated; however, the body temperature of the KCASP1Tg mice decreased rapidly, revealing an impaired thermogenesis ability of the AT due to atrophy. Tumor necrosis factor (TNF)-α, IL-1β and interferon (INF)-γ levels were significantly increased in KCASP1Tg mouse ear skin lesions. To investigate the direct effects of these cytokines, BL/6 wild mice were administered intraperitoneal TNF-α, IL-1β and INF-γ injections, which resulted in small adipocytes with abundant stromal cell infiltration, suggesting those cytokines have a synergistic effect on adipocytes. The systemic dermatitis model mice showed atrophy of AT and increased stromal cells. These findings were reproducible by the intraperitoneal administration of inflammatory cytokines whose production was increased in inflamed skin lesions., Competing Interests: The authors declare no conflict of interest.

Epidermal Langerhans cells (LCs) are skin-resident dendritic cells that are essential for the induction of skin immunity and tolerance. Transforming growth factor-β 1 (TGFβ1) is a crucial factor for LC maintenance and function. However, the underlying TGFβ1 signaling pathways remain unclear. Our previous research has shown that the TGFβ1/Smad3 signaling pathway does not impact LC homeostasis and maturation. In this study, we generated mice with conditional deletions of either individual Smad2, Smad4, or both Smad2 and Smad4 in the LC lineage or myeloid lineage, to further explore the impact of TGFβ1/Smad signaling pathways on LCs. We found that interruption of Smad2 or Smad4 individually or simultaneously in the LC lineage did not significantly impact the maintenance, maturation, antigen uptake, and migration of LCs in vivo or in vitro during steady state. However, the interruption of both Smad2 and Smad4 pathways in the myeloid lineage led to a dramatic inhibition of bone marrow-derived LCs in the inflammatory state. Overall, our data suggest that canonical TGFβ1/Smad2/4 signaling pathways are dispensable for epidermal LC homeostasis and maturation at steady state, but are critical for the long-term LC repopulation directly originating from the bone marrow in the inflammatory state., (Copyright © 2020 Huang, Li, Yu, Xu, Cvetkovski, Wang, Parajuli, Udo-Inyang, Kaplan, Zhou, Yao and Mi.)

Purpose: To evaluate the efficacy/safety of bilastine in pruritus relief in patients with chronic spontaneous urticaria (CSU) or other pruritic skin diseases. Methods: In this multicenter, open-label, exploratory study (EudraCT No.: 2016-001505-17), 115 adults with CSU ( n  = 34), eczema/dermatitis ( n  = 30), prurigo ( n  = 25) or cutaneous pruritus ( n  = 26), received bilastine 20 mg once daily for 8 weeks, or in non-responder patients (<30% improvement in pruritus score at week 2), 40 mg/day from week 2. Results: The mean change in weekly pruritus severity score from baseline to week 8 (primary endpoint) was reduced with bilastine (overall and by disease group); overall, percentage and absolute reductions were 71.16% and 1.63 points, respectively ( p  < .001). Updosed non-responders ( n  = 31) had improved weekly pruritus severity scores from baseline to week 8; percentage and absolute reductions were 49.08% and 1.13 points, respectively ( p  < .001). Bilastine improved the Dermatology Life Quality Index at weeks 4 and 8 ( p  < .001) in all disease groups, and the 7-day Urticaria Activity Score in CSU patients ( p  < .001). Bilastine was well tolerated. Conclusions: Bilastine relieved pruritus associated with urticaria and other skin diseases, with a very good safety profile.

Lumpy skin disease is a high-consequence disease in cattle caused by infection with the poxvirus lumpy skin disease virus (LSDV). The virus is endemic in most countries in Africa and an emerging threat to cattle populations in Europe and Asia. As LSDV spreads into new regions, it is important that signs of disease are recognized promptly by animal caregivers. This study describes the gross, microscopic, and ultrastructural changes that occur over time in cattle experimentally challenged with LSDV. Four calves were inoculated with wildtype LSDV and monitored for 19 to 21 days. At 7 days after inoculation, 2 of the 4 cattle developed multifocal cutaneous nodules characteristic of LSD. Some lesions displayed a targetoid appearance. Histologically, intercellular and intracellular edema was present in the epidermis of some nodules. Occasional intracytoplasmic inclusion bodies were identified in keratinocytes. More severe and consistent changes were present in the dermis, with marked histiocytic inflammation and necrotizing fibrinoid vasculitis of dermal vessels, particularly the deep dermal plexus. Chronic lesions consisted of full-thickness necrosis of the dermis and epidermis. Lesions in other body organs were not a major feature of LSD in this study, highlighting the strong cutaneous tropism of this virus. Immunohistochemistry and electron microscopy identified LSDV-infected histiocytes and fibroblasts in the skin nodules of affected cattle. This study highlights the noteworthy lesions of LSDV and how they develop over time.