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Regulatory myeloid immune cells, such as myeloid-derived suppressor cells (MDSCs), populate inflamed or cancerous tissue and block immune cell effector functions. The lack of mechanistic insight into MDSC suppressive activity and a marker for their identification has hampered attempts to overcome T cell inhibition and unleash anti-cancer immunity. Here, we report that human MDSCs were characterized by strongly reduced metabolism and conferred this compromised metabolic state to CD8 + T cells, thereby paralyzing their effector functions. We identified accumulation of the dicarbonyl radical methylglyoxal, generated by semicarbazide-sensitive amine oxidase, to cause the metabolic phenotype of MDSCs and MDSC-mediated paralysis of CD8 + T cells. In a murine cancer model, neutralization of dicarbonyl activity overcame MDSC-mediated T cell suppression and, together with checkpoint inhibition, improved the efficacy of cancer immune therapy. Our results identify the dicarbonyl methylglyoxal as a marker metabolite for MDSCs that mediates T cell paralysis and can serve as a target to improve cancer immune therapy.

Background: Key pathogenic events of psoriasis and atopic eczema (AE) are misguided immune reactions of the skin. IL-17C is an epithelial-derived cytokine, whose impact on skin inflammation is unclear., Objective: We sought to characterize the role of IL-17C in human ISD., Methods: IL-17C gene and protein expression was assessed by immunohistochemistry and transcriptome analysis. Primary human keratinocytes were stimulated and expression of cytokines chemokines was determined by qRT-PCR and luminex assay. Neutrophil migration towards supernatant of stimulated keratinocytes was assessed. IL-17C was depleted using a new IL-17C-specific antibody (MOR106) in murine models of psoriasis (IL-23 injection model) and AE (MC903 model) as well as in human skin biopsies of psoriasis and AE. Effects on cell influx (mouse models) and gene expression (human explant cultures) were determined., Results: Expression of IL-17C mRNA and protein was elevated in various ISD. We demonstrate that IL-17C potentiates the expression of innate cytokines, antimicrobial peptides (IL-36G, S100A7 and HBD2) and chemokines (CXCL8, CXCL10, CCL5 and VEGF) and the autocrine induction of IL-17C in keratinocytes. Cell-free supernatant of keratinocytes stimulated with IL-17C was strongly chemotactic for neutrophils, thus demonstrating a critical role for IL-17C in immune cell recruitment. IL-17C depletion significantly reduced cell numbers of T cells, neutrophils and eosinophils in murine models of psoriasis and AE and led to a significant downregulation of inflammatory mediators in human skin biopsies of psoriasis and AE ex vivo., Conclusion: IL-17C amplifies epithelial inflammation in Th2 and Th17 dominated skin inflammation and represents a promising target for the treatment of ISD., (© 2019 European Academy of Dermatology and Venereology.)

Allergies are typically endemic, complex and heterogeneous diseases with a high impact at quality of life. Mechanistically, type 2 immune responses involving eosinophil and basophil granulocytes, mast cells and humoral factors such as IgE are key drivers of allergic diseases. Fighting allergic diseases knows three strategies: prevention, symptomatic and causative therapy. While remarkable progress was made in understanding molecular events in allergies as a prerequisite for effective prevention and desensitization, this review article focuses on the most efficient symptomatic treatments-that is using more and more specific antibodies neutralizing particular immune pathways. We highlight and classify recent and upcoming developments in the three prototype chronic allergic diseases allergic asthma, chronic spontaneous urticaria and atopic eczema. In all three examples, biologics such as dupilumab or omalizumab become reliable and efficient therapeutic options. Finally, we give an outlook how a diagnostic and therapeutic workflow might look like in the near future for these three major burdens of society., (© 2020 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.)

This update on chronic urticaria (CU) focuses on the prevalence and pathogenesis of chronic spontaneous urticaria (CSU), the expanding spectrum of patient-reported outcome measures (PROMs) for assessing CU disease activity, impact, and control, as well as future treatment options for CU. This update is needed, as several recently reported findings have led to significant advances in these areas. Some of these key discoveries were first presented at past meetings of the Collegium Internationale Allergologicum (CIA). New evidence shows that the prevalence of CSU is geographically heterogeneous, high in all age groups, and increasing. Several recent reports have helped to better characterize two endotypes of CSU: type I autoimmune (or autoallergic) CSU, driven by IgE to autoallergens, and type IIb autoimmune CSU, which is due to mast cell (MC)-targeted autoantibodies. The aim of treatment in CU is complete disease control with absence of signs and symptoms as well as normalization of quality of life (QoL). This is best monitored by the use of an expanding set of PROMs, to which the Angioedema Control Test, the Cholinergic Urticaria Quality of Life Questionnaire, and the Cholinergic Urticaria Activity Score have recently been added. Current treatment approaches for CU under development include drugs that inhibit the effects of signals that drive MC activation and accumulation, drugs that inhibit intracellular pathways of MC activation and degranulation, and drugs that silence MCs by binding to inhibitory receptors. The understanding, knowledge, and management of CU are rapidly increasing. The aim of this review is to provide physicians who treat CU patients with an update on where we stand and where we will go. Many questions and unmet needs remain to be addressed, such as the development of routine diagnostic tests for type I and type IIb autoimmune CSU, the global dissemination and consistent use of PROMs to assess disease activity, impact, and control, and the development of more effective and well-tolerated long-term treatments for all forms of CU., (© 2020 The Author(s) Published by S. Karger AG, Basel.)

Background: Conventional analyses present aggregate data, masking late responders and efficacy reductions. Secukinumab, a fully human monoclonal antibody that selectively neutralizes interleukin (IL)-17A, shows sustained efficacy in moderate-to-severe psoriasis., Objectives: To determine stability of response to secukinumab, changes in efficacy were assessed in individual patients., Methods: This is a post hoc analysis of two phase III randomized controlled trials, FIXTURE (trial registration: NCT01358578) and CLEAR (trial registration: NCT02074982). Patients received secukinumab 300 mg (FIXTURE and CLEAR), etanercept 50 mg (FIXTURE) or ustekinumab 45 or 90 mg (CLEAR) over 52 weeks. Mutually exclusive response categories were defined: ≥ 90% improvement in the Psoriasis Area and Severity Index (PASI 90) ('excellent'), ≥ 75% improvement in PASI (PASI 75) and < PASI 90 ('good') and < PASI 75 ('insufficient'). Reductions in efficacy were defined as shifts from higher to lower response categories between two consecutive visits maintained for a third consecutive visit. Loss of efficacy was defined as a reduction of efficacy resulting in 'insufficient' response. All comparisons are descriptive., Results: At 52 weeks, in CLEAR, 90·2% (303/336) of patients on secukinumab achieved stable efficacy without loss and 77·7% (261/336) showed stable efficacy without any reduction of response [74·3% (252/339) and 59·9% (203/339) of patients for ustekinumab]. In FIXTURE, 83·5% (273/327) and 66·4% (217/327) of patients on secukinumab had stable efficacy without loss or reduction of response [58·3% (190/326) and 42·6% (139/326) for etanercept]. Response was regained by continuing secukinumab treatment in 50% (8/16) of patients in CLEAR and 26% (9/34) in FIXTURE. Similar patterns were observed for other response definitions., Conclusions: Efficacy with secukinumab was stable over 52 weeks of treatment in most patients. Continued treatment with secukinumab resulted in regain of efficacy in some patients. Persistent loss of response was uncommon. What's already known about this topic? Secukinumab, a fully human monoclonal antibody that selectively neutralizes interleukin (IL)-17A, shows significant and sustained efficacy in the treatment of moderate-to-severe psoriasis. Secondary loss of response may be experienced by a minority of patients treated with secukinumab, as with other biologics, but the extent of this and the potential for regain of efficacy with continued treatment is not well understood. What does this study add? To determine stability of response to secukinumab and inform clinical practice, changes in efficacy were assessed at individual patient level using response categories. Efficacy with secukinumab was stable over 52 weeks of treatment in most patients, and continued treatment with secukinumab resulted in efficacy regain after loss in some patients. Persistent loss of response was uncommon. Patient factors such as body weight may affect the likelihood of loss of efficacy., (© 2019 British Association of Dermatologists.)

Background: Using current diagnostic tools for hand eczema, namely clinical picture and histology, differential diagnoses such as psoriasis palmaris usually cannot be ruled out., Objectives: Discussion of current diagnostic possibilities for hand eczema; presentation and critical evaluation of proposed biomarkers for molecular diagnostics and outlook how diagnostics in dermatology will change in the near future., Materials and Methods: In this article, we discuss basic research and provide a review of the literature., Results: Molecular diagnostics has the potential to substantially improve diagnosis of hand eczema; prerequisites are prospective validation of proposed markers and availability of valid and cost-effective diagnostics., Conclusions: In the near future, the diagnosis of hand eczema will be complemented by software algorithms and artificial intelligence on the one hand and simple, precise, and economic molecular diagnostic devices on the other.

Detailed assessment of skin conditions or the efficacy of skin treatments could greatly benefit from noninvasively assessing the distribution of cutaneous and subcutaneous structures and biomolecules. We considered ultrawideband raster scan optoacoustic mesoscopy with an extended wavelength range from visible to short-wave infrared and observed previously unseen high-resolution images of lipids colocalized with water, melanin, and hemoglobin distribution in human skin. Based on this contrast, the technique resolves subcutaneous fat, the pilosebaceous unit with complete hair strand and bulb, dermal microvasculature, and epidermal structures. We further visualize melanoidins that form via the Maillard reaction in the ultrathin stratum corneum layer, analyze their absorption spectrum, and separate them from the melanin layer. The suggested method may allow novel interrogation of skin conditions, possibly impacting diagnostics and medical and cosmetic treatments.

Background: Conjunctivitis is common in patients with atopic dermatitis (AD) in general and a commonly reported adverse event in AD clinical trials with dupilumab., Objective: To survey opinions and experience about conjunctivitis occurring in AD, including those during dupilumab treatment in a group of AD experts from the International Eczema Council (IEC)., Methods: Electronic survey and in-person discussion of management strategies., Results: Forty-six (53.5%) IEC members from 19 countries responded to the survey. Consensus was reached for several statements regarding diagnostic workup, referral and treatment. IEC members suggest that patients with AD should (i) routinely be asked about ocular complaints or symptoms, (ii) obtain information about the potential for conjunctivitis before starting dupilumab therapy and (iii) if indicated, be treated with dupilumab despite previous or current conjunctivitis. In cases of new-onset conjunctivitis, there was consensus that dupilumab treatment should be continued when possible, with appropriate referral to an ophthalmologist., Limitations: The study relies on expert opinion from dermatologists. Responses from few dermatologists without dupilumab access were not excluded from the survey., Conclusion: The IEC recommends that dermatologists address conjunctivitis in patients with AD, especially during treatment with dupilumab., (© 2019 The Authors. Journal of the European Academy of Dermatology and Venereology published by John Wiley & Sons Ltd on behalf of European Academy of Dermatology and Venereology.)

IL-17 blockers are among the newer anti-psoriatic treatment options and little is known about the interclass switching. We have thus initiated a multi-center, multi-national, retrospective study to assess the treatment response of patients who were switched from one IL-17 blocker to another. Analysis consisted of data from patients with moderate-to-severe psoriasis who did not respond satisfactorily to one of the available IL-17 blockers (secukinumab, ixekizumab, brodalumab) and were subsequently switched to another drug of this class. After 12 weeks of treatment, patients' PASIs were evaluated. Treatment success was defined as reaching PASI 75 after 12 weeks. Topical treatment was allowed and used in all patients. 26 patients were included (13 male, 13 female) and 29 switches were evaluated. Overall, 29 switches in 21 patients were evaluated. 18 patients changed their therapy from secukinumab to ixekizumab, or in 7 cases to brodalumab. Brodalumab was used in 3 cases after failure of treatment with ixekizumab. Only in one case, non-response of brodalumab resulted in a therapy switch to secukinumab. In 15 (52%) cases, PASI 75 was reached. In 6 (20%) patients, the switch led to a PASI 50 response. No success of treatment was seen among 8 (28%) participants. When patients fail to respond or do not tolerate an IL-17 blocker, switching to another anti-IL-17A/RA is a promising viable option. Larger studies are needed to confirm our results.

Background: Hymenoptera venom sensitization in highly exposed individuals frequently requires risk assessment for future severe sting reactions. In this study, we determined the prevalence of Hymenoptera venom sensitization in individuals who hunt and fish and analyzed possible correlations between the severity of sting reactions and the IgE sensitization profile., Methods: In this cross-sectional study, paper-based, self-filled questionnaires about previous insect stings and sting reactions were obtained from individuals who hunt and fish in Bavaria, Germany. Blood samples were taken and analyzed for the levels of tryptase, total IgE and IgE to honey bee (i1) and wasp (13) venom, the recombinant allergens rApi m 1, rApi m 2, rApi m 3, rApi m 5, rApi m 10, rVes v 1, rVes v 5, and the CCD marker molecule MUXF3. Odd ratios (ORs) for sensitization and anaphylaxis and Pearson's correlations for the different allergens were calculated., Results: Of 257 participants, 50.2% showed a sensitization to honey bee venom (i1), and 58.4% showed sensitization to wasp venom (i3). A total of 98.4% of participants claimed to have been stung at least once. Anaphylaxis was reported in 18.7%, and a local sting reaction was reported in 18.3%. The highest sensitization rates were found for whole venom extracts, sensitization to any of the available recombinant allergens exceeded sIgE levels to honeybee venom (i1) in 28.5% and to wasp venom (i3) in 52.9% of participants. Participants with a history of more than 5 stings showed a higher risk for anaphylaxis., Conclusions: Sensitization to Hymenoptera venom and their recombinant allergens are present in the majority of individuals who hunt and fish. Sensitization to distinct recombinant allergens does not necessarily affect the severity of sting reactions including anaphylaxis. A meticulous medical history of the number of previous stings as well as systemic reactions remains essential.

In recent years, several non-invasive imaging methods have been introduced to facilitate diagnostics and therapy monitoring in dermatology. The microscopic imaging methods are restricted in their penetration depth, while the mesoscopic methods probe deeper but provide only morphological, not functional, information. 'Raster-scan optoacoustic mesoscopy' (RSOM), an emerging new imaging technique, combines deep penetration with contrast based on light absorption, which provides morphological, molecular and functional information. Here, we compare the capabilities and limitations of currently available dermatological imaging methods and highlight the principles and unique abilities of RSOM. We illustrate the clinical potential of RSOM, in particular for non-invasive diagnosis and monitoring of inflammatory and oncological skin diseases., (© 2018 The Authors. Journal of the European Academy of Dermatology and Venereology published by John Wiley & Sons Ltd on behalf of European Academy of Dermatology and Venereology.)

Psoriasis is a T helper type 17-mediated immune disease. Initial triggers that lead to T helper type 17 production and inflammatory cell recruitment into skin are being delineated. Autoantigens that stimulate T helper type 17 cells are also being identified. A new and important piece of the puzzle indicates that keratinocytes not only amplify inflammation, but that they are essential for a full-blown IL-17-mediated psoriatic phenotype in mice., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Darier disease is a rare autosomal-dominant genodermatosis with a loss of function of a Ca 2+ -ATPase pump (SERCA2-pump). Clinically, the disease is characterized by red-brown keratotic papules mainly in seborrhoeic areas and has only limited and unsatisfactory treatment options. Previously, low-dose naltrexone was described as a successful treatment option in Hailey-Hailey disease, a genodermatosis with a genetic mutation coding for a similar loss of function of a Ca 2+ -ATPase pump (hSPCA1-pump)., Objective: To assess the efficacy of low-dose naltrexone as a treatment option in Darier disease., Methods: Six patients with biopsy-proven Darier disease (four had severe, one had moderate and one mild clinical manifestations). The patients received off-label therapy with naltrexone [5 mg per os (p.o.)] and magnesium [200 mg p.o.]. Patients were followed up every 4 weeks for minimally 12 weeks. Upon clinical presentation, the disease severity and subjective pain and itch scores were assessed, and standardized photographs were obtained., Results: The clinical response to naltrexone varied after 12 weeks. The four patients with severe Darier disease showed worsening after initial improvement during the first 4 weeks, whereas the two patients with a mild to moderate clinical manifestation clearly improved, showing almost full remission after 12 weeks with complete flattening of the keratotic papules., Conclusion: Low-dose naltrexone did not have an effect on severe Darier disease compared to Hailey-Hailey disease, but it was beneficial in mild to moderate forms of the disease. Further studies are needed to confirm these observations of variable responses., (© 2019 European Academy of Dermatology and Venereology.)

Pollen exposure is a major cause of respiratory allergies worldwide. However, it is unclear how everyday exposure is related to symptoms and how allergic patients may be affected spatially and temporally. Hence, we investigated the relationship of pollen, symptoms and immune responses under a controlled regime of 'high-low-moderate' pollen exposure in urban versus alpine environment. The research was conducted in 2016 in two locations in Germany: urban Augsburg (494 m) and Schneefernerhaus (UFS) on Zugspitze mountain (2656 m). Monitoring of airborne pollen took place using Hirst-type volumetric traps. On UFS, both indoor and outdoor samples were taken. Grass pollen allergic human volunteers were monitored daily during the peak of the grass pollen season, in Augsburg, on UFS, then again in Augsburg. Nasal biosamples were obtained throughout the study to investigate immune responses. All symptoms decreased significantly during the stay on UFS and remained low even after the return to Augsburg. The same was observed for nasal total IgE and IgM levels and for nasal type 2 cytokines and chemokines. Augsburg showed higher pollen concentrations than those on UFS. At all sites, pollen were present throughout each day, but were more abundant in Augsburg during morning. On UFS, outdoor pollen levels were up to 6-fold higher than those indoors. Nasal, ocular and pulmonary symptoms correlated with current and previous days' pollen concentrations and relative humidity. Stays in low-exposure environments during the peak pollen season can be an efficient means of reducing allergic symptoms and immune responses. However, in alpine environments, even occasional pollen exposure during short intervals may still trigger symptoms because of the additional environmental stress posed onto allergics. This highlights the need for the consideration of additional environmental factors, apart from symptom diaries and immune responses, so as to efficiently predict high-risk allergy periods., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The incidence of allergic diseases has increased over the past 50 years, likely due to environmental factors. However, the nature of these factors and the mode of action by which they induce the type 2 immune deviation characteristic of atopic diseases remain unclear. It has previously been reported that dietary sodium chloride promotes the polarization of T helper 17 (T H 17) cells with implications for autoimmune diseases such as multiple sclerosis. Here, we demonstrate that sodium chloride also potently promotes T H 2 cell responses on multiple regulatory levels. Sodium chloride enhanced interleukin-4 (IL-4) and IL-13 production while suppressing interferon-γ (IFN-γ) production in memory T cells. It diverted alternative T cell fates into the T H 2 cell phenotype and also induced de novo T H 2 cell polarization from naïve T cell precursors. Mechanistically, sodium chloride exerted its effects via the osmosensitive transcription factor NFAT5 and the kinase SGK-1, which regulated T H 2 signature cytokines and master transcription factors in hyperosmolar salt conditions. The skin of patients suffering from atopic dermatitis contained elevated sodium compared to nonlesional atopic and healthy skin. These results suggest that sodium chloride represents a so far overlooked cutaneous microenvironmental checkpoint in atopic dermatitis that can induce T H 2 cell responses, the orchestrators of atopic diseases., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Background: Imbalances of T-cell subsets are hallmarks of disease-specific inflammation in psoriasis. However, the relevance of B cells for psoriasis remains poorly investigated., Objective: To analyse the role of B cells and immunoglobulins for the disease-specific immunology of psoriasis., Methods: We characterized B-cell subsets and immunoglobulin levels in untreated psoriasis patients (n = 37) and compared them to healthy controls (n = 20) as well as to psoriasis patients under disease-controlling systemic treatment (n = 28). B-cell subsets were analysed following the flow cytometric gating strategy based on the surface markers CD24, CD38 and CD138. Moreover, immunofluorescence stainings were used to detect IgA in psoriatic skin., Results: We found significantly increased levels of IgA in the serum of treatment-naïve psoriasis patients correlating with disease score. However, IgA was only observed in dermal vessels of skin sections. Concerning B-cell subsets, we only found a moderately positive correlation of CD138 + plasma cells with IgA levels and disease score in treatment-naïve psoriasis patients. Confirming our hypothesis that psoriasis can develop in the absence of functional humoral immunity, we investigated a patient who suffered concomitantly from both psoriasis and a hereditary common variable immune defect (CVID) characterized by a lack of B cells and immunoglobulins. We detected variants in three of the 13 described genes of CVID and a so far undescribed variant in the ligand of the TNFRSF13B receptor leading to disturbed B-cell maturation and antibody production. However, this patient showed typical psoriasis regarding clinical presentation, histology or T-cell infiltrate. Finally, in a group of psoriasis patients under systemic treatment, neither did IgA levels drop nor did plasma cells correlate with IgA levels and disease score., Conclusion: B-cell alterations might rather be an epiphenomenal finding in psoriasis with a clear dominance of T cells over shifts in B-cell subsets., (© 2018 European Academy of Dermatology and Venereology.)

Atopic dermatitis (AD) is a prevalent disease worldwide and is associated with systemic comorbidities representing a significant burden on patients, their families, and society. Therapeutic options for AD remain limited, in part because of a lack of well-characterized animal models. There has been increasing interest in developing experimental approaches to study the pathogenesis of human AD in vivo, in vitro, and in silico to better define pathophysiologic mechanisms and identify novel therapeutic targets and biomarkers that predict therapeutic response. This review critically appraises a range of models, including genetic mutations relevant to AD, experimental challenge of human skin in vivo, tissue culture models, integration of "omics" data sets, and development of predictive computational models. Although no one individual model recapitulates the complex AD pathophysiology, our review highlights insights gained into key elements of cutaneous biology, molecular pathways, and therapeutic target identification through each approach. Recent developments in computational analysis, including application of machine learning and a systems approach to data integration and predictive modeling, highlight the applicability of these methods to AD subclassification (endotyping), therapy development, and precision medicine. Such predictive modeling will highlight knowledge gaps, further inform refinement of biological models, and support new experimental and systems approaches to AD., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: For sufficient treatment of patients with chronic inflammatory skin diseases, new concepts need to be established and biomarkers must be identified., Objective: Presentation of new markers, their quality and implications for the clinical daily routine., Material and Methods: This article presents a discussion of basic research and a review of current achievements of personalized medicine in the area of chronic inflammatory skin diseases., Results: Promising biomarker for the various entities of chronic inflammatory skin diseases have been proposed; however, they need to be prospectively validated and translated into affordable and feasible tests., Conclusion: There is still a long way to go to establish personalized medicine in the field of chronic inflammatory skin diseases and its success is dependent on multicenter collaboration to validate and implement novel biomarkers.

Generalized pustular psoriasis (GPP) is a rare, multisystemic skin disease characterized by recurrent episodes of pustulation. GPP can be life-threatening and is often difficult to treat. In the era of precision medicine in dermatology, GPP stands exemplary for both challenges and chances-while new treatments offer great hope, there is urgent need for better definition and stratification of this severe and heterogeneous disease. Our objective was to systematically review the literature for evidence of efficacy of targeted immunotherapy and their mode of action in the context of clinical phenotype, classification and pathogenesis of adult GPP. Classifying GPP is challenging since clinical criteria for description and diagnosis are not consistent between expert centres. We therefore defined diagnostic feasibility of the reviewed cases by assessing four criteria: compatible clinical history, typical dermatological features and/or diagnostic histopathology, consistent clinical pictures and the DITRA status. Pathogenesis of GPP is mediated by pathways that partly overlap plaque type psoriasis, with a more pronounced activity of the innate immune system. Both IL-1 and IL-36 but also IL-17 play a major role in disease formation. We ascertained a total of 101 published cases according to our predefined criteria and identified TNF-α, IL-12/23, IL-17 and IL-1β as targets for immunotherapy for the treatment of GPP. Of those cases, 61% showed complete response and 27% partial response to targeted immunotherapy. Only 12% experienced weak or no response. These data indicate that specific immunotherapy can be used to effectively treat GPP, with most evidence existing for anti-IL-17 agents., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Interface dermatitis is a characteristic histological pattern that occurs in autoimmune and chronic inflammatory skin diseases. It is unknown whether a common mechanism orchestrates this distinct type of skin inflammation. Here we investigated the overlap of two different interface dermatitis positive skin diseases, lichen planus and lupus erythematosus. The shared transcriptome signature pointed toward a strong type I immune response, and biopsy-derived T cells were dominated by IFN-γ and tumor necrosis factor alpha (TNF-α) positive cells. The transcriptome of keratinocytes stimulated with IFN-γ and TNF-α correlated significantly with the shared gene regulations of lichen planus and lupus erythematosus. IFN-γ, TNF-α, or mixed supernatant of lesional T cells induced signs of keratinocyte cell death in three-dimensional skin equivalents. We detected a significantly enhanced epidermal expression of receptor-interacting-protein-kinase 3, a key regulator of necroptosis, in interface dermatitis. Phosphorylation of receptor-interacting-protein-kinase 3 and mixed lineage kinase domain like pseudokinase was induced in keratinocytes on stimulation with T-cell supernatant-an effect that was dependent on the presence of either IFN-γ or TNF-α in the T-cell supernatant. Small hairpin RNA knockdown of receptor-interacting-protein-kinase 3 prevented cell death of keratinocytes on stimulation with IFN-γ or TNF-α. In conclusion, type I immunity is associated with lichen planus and lupus erythematosus and induces keratinocyte necroptosis. These two mechanisms are potentially involved in interface dermatitis., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

IL-17C is a functionally distinct member of the IL-17 family that was believed to play a role in the pathogenesis of psoriasis. Here we confirmed that IL-17C is involved in psoriasis and explored potential roles for IL-17C in atopic dermatitis (AD). An anti-IL-17C antibody, MOR106, was generated that potently and selectively binds to human and mouse IL-17C, thereby inhibiting the binding of IL-17C to its IL-17RE receptor. The antibody inhibited cutaneous inflammation in an IL-23-induced psoriatic-like skin inflammation model. In lesional skin of patients with AD, IL-17C expression levels were increased and localized to keratinocytes and infiltrating immune cells. To determine the contribution of IL-17C to AD pathogenesis, MOR106 was tested in two distinct in vivo models. In the calcipotriol-induced AD model, ear skin inflammation, TSLP, and IL-33 protein production in ears was suppressed by MOR106. Consistently, in the flaky tail strain mouse model, spontaneous development of AD-like skin inflammation was reduced by MOR106. Moreover, serum IgE levels, number of mast cells in skin and T helper type 2-related cytokines IL-4 and CCL17 in serum were all reduced. Overall, our results indicate that IL-17C is a central mediator of skin inflammation beyond psoriasis and is relevant in particular in AD., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Non-communicable inflammatory skin diseases (ncISD) such as psoriasis or atopic eczema are a major cause of global disease burden. Due to their impact and complexity, ncISD represent a major challenge of modern medicine. Dermatology textbooks describe more than 100 different ncISD based on clinical phenotype and histological architecture. In the last decades, this historical description was complemented by increasing molecular knowledge - and this knowledge is now being translated into specific therapeutics. Combining the enormous advances made in lymphocyte immunology and molecular genetics with clinical and histological phenotyping reveals six immune response patterns of the skin - type I immune cells cause the lichenoid pattern characterized by immune-mediated cell death of keratinocytes; type II immune cells underlie the eczematous pattern with impaired epidermal barrier, infection and eosinophils as well as the bullous pattern with loss of epithelial integrity; Th17 cells and ILC3 mediate the psoriatic pattern characterized by acanthosis, high metabolic activity and neutrophils; dysbalance of regulatory T cells causes either the fibrogenic pattern with rarefication of cells and dermal thickening or the granulomatous pattern defined by formation of granulomas. With more and more specific therapeutic agents approved, classifying ncISD also according to their immune response pattern will become highly relevant. This review defines the six immune response patterns of ncISD and highlights therapeutic strategies targeting key lymphocyte mediators., (© 2017 The Authors. Journal of the European Academy of Dermatology and Venereology published by John Wiley & Sons Ltd on behalf of European Academy of Dermatology and Venereology.)

The skin is the outermost barrier of the organism that ensures protection from external harm. Lately, our view of the skin has evolved from an inert mechanical barrier to an active organ that can sense danger signals and mount perfectly adapted defense measures in response to invading pathogens. This Review highlights the different levels of the cutaneous barrier (the microbiome, chemical, physical, and immune barriers), their characteristics, and functional, highly interconnected network of cells and mediators that allow balanced defense measures to protect the body and maintain barrier integrity., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: A standardized human model to study early pathogenic events in patients with psoriasis is missing. Activation of Toll-like receptor 7/8 by means of topical application of imiquimod is the most commonly used mouse model of psoriasis., Objective: We sought to investigate the potential of a human imiquimod patch test model to resemble human psoriasis., Methods: Imiquimod (Aldara 5% cream; 3M Pharmaceuticals, St Paul, Minn) was applied twice a week to the backs of volunteers (n = 18), and development of skin lesions was monitored over a period of 4 weeks. Consecutive biopsy specimens were taken for whole-genome expression analysis, histology, and T-cell isolation. Plasmacytoid dendritic cells (pDCs) were isolated from whole blood, stimulated with Toll-like receptor 7 agonist, and analyzed by means of extracellular flux analysis and real-time PCR., Results: We demonstrate that imiquimod induces a monomorphic and self-limited inflammatory response in healthy subjects, as well as patients with psoriasis or eczema. The clinical and histologic phenotype, as well as the transcriptome, of imiquimod-induced inflammation in human skin resembles acute contact dermatitis rather than psoriasis. Nevertheless, the imiquimod model mimics the hallmarks of psoriasis. In contrast to classical contact dermatitis, in which myeloid dendritic cells sense haptens, pDCs are primary sensors of imiquimod. They respond with production of proinflammatory and T H 17-skewing cytokines, resulting in a T H 17 immune response with IL-23 as a key driver. In a proof-of-concept setting systemic treatment with ustekinumab diminished imiquimod-induced inflammation., Conclusion: In human subjects imiquimod induces contact dermatitis with the distinctive feature that pDCs are the primary sensors, leading to an IL-23/T H 17 deviation. Despite these shortcomings, the human imiquimod model might be useful to investigate early pathogenic events and prove molecular concepts in patients with psoriasis., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Atopic dermatitis (AD) is one of the most common chronic inflammatory diseases and is also one of the most frequent reasons to consult a dermatologist. Over the past few years there has been a rapidly growing understanding of the cellular, molecular and immunological relationships as well as genetic variations, which leads to a better comprehension of the disease. Consequently, there are innovative targeted therapies in clinical studies or already approved for therapy. To make reasonable use of the new targeted therapies a good understanding of the pathogenesis is very important. In the future, stratification of patients with AD and the resulting personalized therapies will gain in importance. This review depicts the up to date state of knowledge on the complex pathogenesis of AD.

Background: The main function of sebocytes is considered to be the production of lipids to moisturize the skin. However, it recently became apparent that sebocytes release chemokines and cytokines and respond to proinflammatory stimuli as well as the presence of bacteria., Objectives: To analyse the functional communication between human sebocytes and T cells., Methods: Immunofluorescence stainings for CD4 and interleukin (IL)-17 were performed on acne sections and healthy skin. Migration assays and T-cell-stimulation cultures were performed with supernatants derived from unstimulated or prestimulated SZ95 sebocytes. Dendritic cells were generated in the presence of SZ95 supernatant and subsequently used in mixed leucocyte reactions., Results: We showed that CD4 + IL-17 + T cells accumulate around the pilosebaceous unit and are in close contact with sebocytes in acne lesions. By using SZ95 sebocyte supernatant, we demonstrate a chemotactic effect of sebocytes on neutrophils, monocytes and T cells in a CXCL8-dependent manner. Furthermore, sebocyte supernatant induces the differentiation of CD4 + CD45RA + naive T cells into T helper (Th)17 cells via the secretion of IL-6, transforming growth factor-β and, most importantly, IL-1β. No direct effects of sebocytes on the function of CD4 + CD45RO + memory T cells were detected. Moreover, sebocytes functionally interact with Propionibacterium acnes in the maturation of dendritic cells, leading to antigen-presenting cells that preferentially prime Th17 cells., Conclusions: Our study provides evidence that human sebocytes actively participate in inflammatory processes in the skin by recruiting and communicating with immune cells. This interaction leads to the generation of Th17 cells, which might contribute to the pathogenesis not only of acne vulgaris, but also of several inflammatory skin diseases., (© 2017 British Association of Dermatologists.)

Background: Guidelines discourage the use of systemic corticosteroids for atopic dermatitis (AD), but their use remains widespread., Objectives: To reach consensus among an international group of AD experts on the use of systemic corticosteroids for AD., Methods: A survey consisting of statements accompanied by visual analogue scales ranging from 'strongly disagree' to 'neutral' to 'strongly agree' was distributed to the International Eczema Council (IEC). Consensus was reached in agreement on a statement if < 30% of respondents marked to the left of 'neutral' towards 'strongly disagree'., Results: Sixty of 77 (78%) IEC members participated. Consensus was reached on 12 statements, including that systemic corticosteroids should generally be avoided but can be used rarely for severe AD under certain circumstances, including a lack of other treatment options, as a bridge to other systemic therapies or phototherapy, during acute flares in need of immediate relief, in anticipation of a major life event or in the most severe cases. If used, treatment should be limited to the short term. Most respondents agreed that systemic corticosteroids should never be used in children, but consensus was not reached on that statement. The conclusions of our expert group are limited by a dearth of high-quality published evidence. If more stringent consensus criteria were applied (e.g. requiring < 20% of respondents marking towards 'strongly disagree'), consensus would have been reached on fewer statements., Conclusions: Based on expert opinion from the IEC, routine use of systemic corticosteroids for AD is generally discouraged and should be reserved for special circumstances., (© 2017 The Authors. British Journal of Dermatology published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.)

Nailfold capillaroscopy, based on bright-field microscopy, is widely used to diagnose systemic sclerosis (SSc). However it cannot reveal information about venules and arterioles lying deep under the nailfold, nor can it provide detailed data about surface microvasculature when the skin around the nail is thick. These limitations reflect the fact that capillaroscopy is based on microscopy methods whose penetration depth is restricted to about 200 μm. We investigated whether ultra-wideband raster-scan optoacoustic mesoscopy (UWB-RSOM) can resolve small capillaries of the nailfold in healthy volunteers and compared the optoacoustic data to conventional capillaroscopy examinations. We quantified UWB-RSOM-resolved capillary density and capillary diameter as features that relate to SSc biomarkers, and we obtained the first three-dimensional, in vivo images of the deeper arterioles and venules. These results establish the potential of UWB-RSOM for analyzing SSc-relevant markers.

Background: As lipids are known to regulate macrophage functions, it is reasonable to suppose that a sebocyte-macrophage axis mediated by sebum lipids may exist., Objectives: To investigate if sebocytes could contribute to the differentiation, polarization and function of macrophages with their secreted lipids., Methods: Oil Red O lipid staining and Raman spectroscopy were used to assess the dermal lipid content and penetration. Immunohistochemistry was used to analyse the macrophage subsets. Human peripheral blood monocytes were differentiated in the presence of either supernatant from human SZ95 sebocytes or major sebum lipid components and activated with Propionibacterium acnes. Macrophage surface markers and their capacity to uptake fluorescein isothiocyanate-conjugated P. acnes were detected by fluorescence-activated cell sorting measurements. Cytokine protein levels were evaluated by enzyme-linked immunosorbent assay and Western blot analysis., Results: Sebaceous gland-rich skin had an increased dermal lipid content vs. sebaceous gland-poor skin to which all the tested sebum component lipids could contribute by penetrating the dermoepidermal barrier. Of the lipids, oleic acid and linoleic acid promoted monocyte differentiation into alternatively activated macrophages. Moreover, linoleic acid also had an anti-inflammatory effect in P. acnes-activated macrophages, inhibiting the secretion of interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α. Squalene, palmitic acid, stearic acid and oleic acid augmented the secretion of IL-1β, even in the absence of P. acnes, whereas oleic acid had a selective effect of inducing IL-1β but downregulating IL-6 and TNF-α secretion., Conclusions: Our results suggest a role for sebaceous glands in modulating innate immune responses via their secreted lipids that are of possible pathological and therapeutic relevance., (© 2017 British Association of Dermatologists.)

Objectives: To determine the causes of death and risk factors in systemic sclerosis (SSc)., Methods: Between 2000 and 2011, we examined the death certificates of all French patients with SSc to determine causes of death. Then we examined causes of death and developed a score associated with all-cause mortality from the international European Scleroderma Trials and Research (EUSTAR) database. Candidate prognostic factors were tested by Cox proportional hazards regression model by single variable analysis, followed by a multiple variable model stratified by centres. The bootstrapping technique was used for internal validation., Results: We identified 2719 French certificates of deaths related to SSc, mainly from cardiac (31%) and respiratory (18%) causes, and an increase in SSc-specific mortality over time. Over a median follow-up of 2.3 years, 1072 (9.6%) of 11 193 patients from the EUSTAR sample died, from cardiac disease in 27% and respiratory causes in 17%. By multiple variable analysis, a risk score was developed, which accurately predicted the 3-year mortality, with an area under the curve of 0.82. The 3-year survival of patients in the upper quartile was 53%, in contrast with 98% in the first quartile., Conclusion: Combining two complementary and detailed databases enabled the collection of an unprecedented 3700 deaths, revealing the major contribution of the cardiopulmonary system to SSc mortality. We also developed a robust score to risk-stratify these patients and estimate their 3-year survival. With the emergence of new therapies, these important observations should help caregivers plan and refine the monitoring and management to prolong these patients' survival., Competing Interests: Competing interests: OD reports personal fees from 4D Science, grants and personal fees from Actelion, personal fees from Active Biotech, grants and personal fees from Bayer, personal fees from Biogen Idec, personal fees from BMS, grants and personal fees from Boehringer Ingelheim, personal fees from ChemomAb, personal fees from EpiPharm, personal fees from EspeRare Foundation, personal fees from Genentech/Roche, personal fees from GSK, personal fees from Inventiva, personal fees from Lilly, personal fees from Medac, personal fees from Mepha, personal fees from MedImmune, personal fees from Pharmacyclics, grants and personal fees from Pfizer, grants and personal fees from Sanofi, personal fees from Serodapharm, personal fees from Sinoxa, personal fees from AbbVie, personal fees from iQone Healthcare, outside the submitted work. In addition, OD has a patent mir-29 for the treatment of systemic sclerosis licensed. FI reports personal fees from AbbVie, personal fees from BMS, personal fees from MSD, personal fees from Novartis, outside the submitted work. JHWD reports personal fees from Actelion, grants and personal fees from Anamar, grants and personal fees from Bayer Pharma, grants and personal fees from Boehringer Ingelheim, grants from Celgene, personal fees from Galapagos, grants from GSK, grants and personal fees from Inventiva, personal fees from Pfizer, grants and personal fees from UCB, grants from Novartis, other from 4D Science, outside the submitted work. JvL reports personal fees from Pfizer, grants and personal fees from MSD, personal fees from Eli Lilly, personal fees from BMS, personal fees from Roche, outside the submitted work. Other coauthors have nothing to disclose., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)