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Rosacea is a common chronic inflammatory skin disease with a fluctuating course of excessive inflammation and apparent neovascularization. Microbial dysbiosis with a high density of Bacillus oleronius and increased activity of kallikrein 5, which cleaves cathelicidin antimicrobial peptide, are key pathogenic triggers in rosacea. However, how these events are linked to the disease remains unknown. Here, we show that type I IFNs produced by plasmacytoid DCs represent the pivotal link between dysbiosis, the aberrant immune response, and neovascularization. Compared with other commensal bacteria, B. oleronius is highly susceptible and preferentially killed by cathelicidin antimicrobial peptides, leading to enhanced generation of complexes with bacterial DNA. These bacterial DNA complexes but not DNA complexes derived from host cells are required for cathelicidin-induced activation of plasmacytoid DCs and type I IFN production. Moreover, kallikrein 5 cleaves cathelicidin into peptides with heightened DNA binding and type I IFN-inducing capacities. In turn, excessive type I IFN expression drives neoangiogenesis via IL-22 induction and upregulation of the IL-22 receptor on endothelial cells. These findings unravel a potentially novel pathomechanism that directly links hallmarks of rosacea to the killing of dysbiotic commensal bacteria with induction of a pathogenic type I IFN-driven and IL-22-mediated angiogenesis.

Tumors invade the surrounding tissues to progress, but the heterogeneity of cell types at the tumor-stroma interface and the complexity of their potential interactions hampered mechanistic insight required for efficient therapeutic targeting. Here, combining single-cell and spatial transcriptomics on human basal cell carcinomas, we define the cellular contributors of tumor progression. In the invasive niche, tumor cells exhibit a collective migration phenotype, characterized by the expression of cell-cell junction complexes. In physical proximity, we identify cancer-associated fibroblasts with extracellular matrix-remodeling features. Tumor cells strongly express the cytokine Activin A, and increased Activin A-induced gene signature is found in adjacent cancer-associated fibroblast subpopulations. Altogether, our data identify the cell populations and their transcriptional reprogramming contributing to the spatial organization of the basal cell carcinoma invasive niche. They also demonstrate the power of integrated spatial and single-cell multi-omics to decipher cancer-specific invasive properties and develop targeted therapies., Nature Communications, 13 (1), ISSN:2041-1723

Human cells produce thousands of lipids that change during cell differentiation and can vary across individual cells of the same type. However, we are only starting to characterize the function of these cell-to-cell differences in lipid composition. Here, we measured the lipidomes and transcriptomes of individual human dermal fibroblasts by coupling high-resolution mass spectrometry imaging with single-cell transcriptomics. We found that the cell-to-cell variations of specific lipid metabolic pathways contribute to the establishment of cell states involved in the organization of skin architecture. Sphingolipid composition is shown to define fibroblast subpopulations, with sphingolipid metabolic rewiring driving cell-state transitions. Therefore, cell-to-cell lipid heterogeneity affects the determination of cell states, adding a new regulatory component to the self-organization of multicellular systems.

Skin wounds heal by coordinated induction of inflammation and tissue repair, but the initiating events are poorly defined. Here we uncover a fundamental role of commensal skin microbiota in this process and show that it is mediated by the recruitment and the activation of type I interferon (IFN)-producing plasmacytoid DC (pDC). Commensal bacteria colonizing skin wounds trigger activation of neutrophils to express the chemokine CXCL10, which recruits pDC and acts as an antimicrobial protein to kill exposed microbiota, leading to the formation of CXCL10–bacterial DNA complexes. These complexes and not complexes with host-derived DNA activate pDC to produce type I IFNs, which accelerate wound closure by triggering skin inflammation and early T cell–independent wound repair responses, mediated by macrophages and fibroblasts that produce major growth factors required for healing. These findings identify a key function of commensal microbiota in driving a central innate wound healing response of the skin. Gilliet and colleagues demonstrate that skin wound healing occurs through the coordinated action of plasmacytoid dendritic cells, chemokines and skin microbiota.

LL37 exerts a dual pathogenic role in psoriasis. Bound to self-DNA/RNA, LL37 licenses autoreactivity by stimulating plasmacytoid dendritic cells-(pDCs)-Type I interferon (IFN-I) and acts as autoantigen for pathogenic Th17-cells. In systemic lupus erythematosus (SLE), LL37 also triggers IFN-I in pDCs and is target of pathogenic autoantibodies. However, whether LL37 activates T-cells in SLE and how the latter differ from psoriasis LL37-specific T-cells is unknown. Here we found that 45% SLE patients had circulating T-cells strongly responding to LL37, which correlate with anti-LL37 antibodies/disease activity. In contrast to psoriatic Th17-cells, these LL37-specific SLE T-cells displayed a T-follicular helper-(TFH)-like phenotype, with CXCR5/Bcl-6 and IL-21 expression, implicating a role in stimulation of pathogenic autoantibodies. Accordingly, SLE LL37-specific T-cells promoted B-cell secretion of pathogenic anti-LL37 antibodies in vitro. Importantly, we identified abundant citrullinated LL37 (cit-LL37) in SLE tissues (skin and kidney) and observed very pronounced reactivity of LL37-specific SLE T-cells to cit-LL37, compared to native-LL37, which was much more occasional in psoriasis. Thus, in SLE, we identified LL37-specific T-cells with a distinct functional specialization and antigenic specificity. This suggests that autoantigenic specificity is independent from the nature of the autoantigen, but rather relies on the disease-specific milieu driving T-cell subset polarization and autoantigen modifications.

DUSP22 gene rearrangements are recurrent in systemic and cutaneous ALK-negative anaplastic large cell lymphomas, rarely encountered in other cutaneous CD30+ lymphoproliferations, and typically absent in other peripheral T-cell lymphomas. We report the case of a 51-year-old woman, with longstanding celiac disease and a rapidly enlarging leg ulcer, due to a DUSP22-rearranged CD30+ T-cell lymphoproliferation. Subsequent history revealed an intestinal enteropathy-associated T-cell lymphoma (EATL). Identical monoclonal TR gene rearrangements and mutations in STAT3 and JAK1 typical of EATL were present in the cutaneous and intestinal lesions. No DUSP22 rearrangement was detected in the patient's intestinal tumour, nor in 15 additional EATLs tested. These findings indicate that DUSP22 rearrangements are not entirely specific of ALCLs, may rarely occur as a secondary aberration in EATL, and expand the differential diagnosis of DUSP22-rearranged cutaneous CD30+ lymphoproliferative disorders.

COVID-19, which is caused by infection with SARS-CoV-2, is characterized by lung pathology and extrapulmonary complications

Since the beginning of the COVID-19 pandemic, dermatologists around the world have reported patients with chilblain-like skin lesions on their toes, called COVID-toes. Surprisingly, the majority of these patients do not develop COVID-19 symptoms, and their nasal swabs and serological tests are unable to confirm SARS-CoV-2 infection, despite a clear exposure to the virus. Recent evidence suggests that these patients mount a robust type I interferon response to SARS-CoV-2, making them resistant to the infection. Because chilblains are hallmarks of excessive type I interferons, COVID-toes may represent the skin expression of interferon-mediated resistance to SARS-CoV-2. Uncovering the molecular patho-mechanisms of COVID-toes may provide new avenues to promote SARS-CoV-2 resistance and control the COVID-19 pandemic.Depuis le début de la pandémie de Covid-19, les dermatologues du monde entier ont signalé des cas inexpliqués de pseudo-engelures, surnommées « orteils Covid » (COVID-toes). Cette recrudescence inhabituelle de pseudo-engelures est d’autant plus intrigante que la majorité des cas ne présentent pas de symptômes de Covid-19 ni de PCR ou de sérologie positive, malgré une exposition probable au SARS-CoV-2. Les données actuelles suggèrent que ces personnes sont prédisposées à induire une immunité innée robuste contre le SARS-CoV-2, ce qui les rend résistantes à l’infection. Une forte réponse interféron de type I, dont les pseudo-engelures sont l’expression clinique, pourrait favoriser une clairance rapide du virus, évitant à la fois la maladie et la séroconversion. Les mécanismes génétiques et moléculaires qui sous-tendent cette résistance naturelle au SARS-CoV-2 restent cependant à élucider.

Myeloid cells orchestrate the antitumor immune response and influence the efficacy of immune checkpoint blockade (ICB) therapies. We and others have previously shown that IL-32 mediates DC differentiation and macrophage activation. Here, we demonstrate that IL-32 expression in human melanoma positively correlates with overall survival, response to ICB, and an immune-inflamed tumor microenvironment (TME) enriched in mature DC, M1 macrophages, and CD8+ T cells. Treatment of B16F10 murine melanomas with IL-32 increased the frequencies of activated, tumor-specific CD8+ T cells, leading to the induction of systemic tumor immunity. Our mechanistic in vivo studies revealed a potentially novel role of IL-32 in activating intratumoral DC and macrophages to act in concert to prime CD8+ T cells and recruit them into the TME through CCL5. Thereby, IL-32 treatment reduced tumor growth and rendered ICB-resistant B16F10 tumors responsive to anti–PD-1 therapy without toxicity. Furthermore, increased baseline IL-32 gene expression was associated with response to nivolumab and pembrolizumab in 2 independent cohorts of patients with melanoma, implying that IL-32 is a predictive biomarker for anti–PD-1 therapy. Collectively, this study suggests IL-32 as a potent adjuvant in immunotherapy to enhance the efficacy of ICB in patients with non–T cell–inflamed TME., IL-32 treatment reprograms DC and macrophages to induce CD8+ T cell infiltration, thereby promoting tumor immunity and response to immunotherapy in murine models of melanoma.

Basal cell carcinoma (BCC) is the most frequent human cancer and is becoming an important health problem in an aging population. Based on their clinical and histological characteristics, thick BCC are typically divided into low-risk nodular and high-risk infiltrative subtypes, although the underlying mechanisms are poorly understood. We have identified molecular mechanisms that explain the aggressiveness of high-risk infiltrative BCC, with a potential direct clinical impact. In this study, we first show that fibroblasts, transforming growth factor-β, and fibronectin are found preferentially in infiltrative human BCC. This allowed us to develop in vivo models for the study of infiltrative BCC, which in turn let us confirm the role of transforming growth factor-β in inducing peritumoral fibronectin deposition and tumor infiltration. We then show that fibronectin promotes adhesion and migration of BCC cell lines through integrin α5β1-mediated phosphorylation of focal adhesion kinase. Fittingly, both inhibition of integrin α5β1 and phospho-focal adhesion kinase prevent fibronectin-induced migration of BCC cells in vitro as well as BCC infiltration in vivo. Altogether, our results open important insights into the pathogenesis of aggressive infiltrative BCC and identify integrin α5β1 or focal adhesion kinase inhibition as promising strategies for the treatment of advanced BCC.

Lupus erythematosus (LE) patients develop autoantibodies that form circulating immune complexes (ICs) with extracellular self-nucleic acids. These ICs are deposited into peripheral tissues, where they trigger detrimental organ inflammation. Recent evidence suggests that ICs contain LL37–DNA complexes derived from neutrophil extracellular traps (NETs) and that LE patients develop pathogenic autoantibodies against these structures, including Abs to LL37. However, the mechanism that leads to the generation of these Abs is unknown. In this study, we show that NETs directly trigger Ab production by human memory B cells. This occurs via LL37–DNA complexes present in NETs, which have the unique ability to gain access to endosomal compartments of B cells and to trigger TLR9 activation. In LE patients, NET-derived LL37–DNA complexes trigger polyclonal B cell activation via TLR9, but also specifically expand self-reactive memory B cells producing anti-LL37 Abs in an Ag-dependent manner. These findings suggest a unique link between neutrophils and B cells in which NETs trigger a concerted activation of TLR9 and BCR leading to anti-NET autoantibody production in lupus.

Although anti-tumor necrosis factor (TNF) agents are highly effective in the treatment of psoriasis, 2–5% of treated patients develop psoriasis-like skin lesions called paradoxical psoriasis. The pathogenesis of this side effect and its distinction from classical psoriasis remain unknown. Here we show that skin lesions from patients with paradoxical psoriasis are characterized by a selective overexpression of type I interferons, dermal accumulation of plasmacytoid dendritic cells (pDC), and reduced T-cell numbers, when compared to classical psoriasis. Anti-TNF treatment prolongs type I interferon production by pDCs through inhibition of their maturation. The resulting type I interferon overexpression is responsible for the skin phenotype of paradoxical psoriasis, which, unlike classical psoriasis, is independent of T cells. These findings indicate that paradoxical psoriasis represents an ongoing overactive innate inflammatory process, driven by pDC-derived type I interferon that does not lead to T-cell autoimmunity., The pathogenesis of paradoxical psoriasis in patients receiving anti-TNF treatments for classical psoriasis is unclear. Here, the authors show that anti-TNF drugs enhance the production of type I interferon by plasmacytoid dendritic cells, causing skin lesions that, unlike classical psoriasis, lack T- cell autoimmunity.

Background: Squamous cell carcinomas and basal cell carcinomas are both induced by chronic UV exposure. However, their predilection for specific areas of the face remains unexplained. Regional factors such as arterial blood flow may explain specific tumor localization. Objective: To determine whether in the fronto-temporal area of the face there is a preferential localization of non-melanoma skin cancer (NMSC) at sites of arterial blood vessels. Methods: Twenty-two patients with NMSC of the fronto-temporal area were selected for this study. The clinical tumor margins were demarked based on clinical examination. Arterial colocalization was determined using both sonography and histological analysis. Results: Echo-Doppler analysis revealed the colocalization of NMSC with an arterial branch in 59% of the patients. Histologically, colocalization between NMSC and artery was found in 68% of the patients. When combining echo-Doppler and histological results, colocalization of NMSC and arteries were found in 82% of the patients. Conclusion: In this study, we found an unexpectedly high colocalization of NMSC with arterial branches in the fronto-temporal area of the face. These results suggest that in addition to UV exposure, pulsatile arterial blood flow may represent an additional factor determining the precise facial localization of NMSC.

BACKGROUND Several treatment options are currently available for the treatment of psoriasis. OBJECTIVE To explore the main associations between patients' characteristics and systemic treatments prescribed for psoriasis in a large group of patients observed in real-life clinical practice. METHODS This was a retrospective analysis of baseline data collected within the Swiss Dermatology Network for Targeted Therapies registry in Switzerland between March 2011 and December 2017. Semantic map analysis was used in order to capture the best associations between variables taking into account other covariates in the system. RESULTS A total of 549 patients (mean age 46.7 ± 14.7 years) were included in the analysis. Conventional therapies such as retinoids and methotrexate were associated with no previous systemic therapies for psoriasis, a moderate quality of life (QoL) at therapy onset and older age (≥60 years). Fumaric acid derivatives were associated with mild psoriasis (psoriasis area severity index

Endosomal and cytosolic nucleic acid receptors are important immune sensors required for the detection of infecting or replicating viruses. The intracellular location of these receptors allows viral recognition and, at the same time, avoids unnecessary immune activation to self-nucleic acids that are continuously released by dying host cells. Recent evidence, however, indicates that endogenous factors such as anti-microbial peptides have the ability to break this protective mechanism. Here, we discuss these factors and illustrate how they drive inflammatory responses by promoting immune recognition of self-nucleic acids in skin wounds and inflammatory skin diseases such as psoriasis and lupus.

Over the last years, several immune pathways in the skin have been identified. These discoveries have been translated into targeted therapies for inflammatory skin diseases, which have revolutionized our clinical practice. The perturbed molecular network in the skin may serve as a biomarker for disease prediction and as a source of targets for early therapeutic intervention or prevention. With rising costs, this disease-focused healthcare model will become unsustainable, therefore next-generation healthcare must not focus solely on treatment personalisation (the right treatment for the right patient), but also needs to shift its focus towards disease prevention and early therapeutic intervention prior to disease manifestation.

BACKGROUND Though patient needs are key drivers of treatment decisions, they are rarely systematically investigated in routine care. OBJECTIVE This study aimed at analysing needs and expectations from the patient perspective in the German and Swiss psoriasis registries PsoBest and SDNTT with respect to treatment choice, age and gender. METHODS The German and Swiss psoriasis registries observe patients recruited at first-time use of systemic drugs. Within 10 years, clinical (Psoriasis Area Severity Index (PASI), Body Surface Area (BSA)) and patient-reported outcomes are documented, including the Dermatology Quality of Life Index (DLQI) and the Patient Benefit Index (PBI), characterizing patient needs for treatment. The analysis dataset includes n=4,894 patients from PsoBest and n=449 from SDNTT with mean follow-up time of 7.5 months. RESULTS 5,343 patients registered between 2008 and 2016 were included in the analyses (at baseline: 59.6% male, mean age 47.6 years±14.5, PASI 14.2±9.7, BSA 22.7±19.7, DLQI 11.3±7.2).The most important patient needs were to "get better skin quickly" and to "be healed of all skin defects". Subgroup analyses by age revealed significant differences in needs, especially higher needs regarding social impairments in patients younger than 65 years. Patients 65 years or older attributed more importance to sleep quality, less dependency on medical visits, fewer side effects and confidence in the therapy. Out of 25 items reflecting patient needs, 20 items were rated significantly more important by women than men, with the greatest differences regarding feeling of depression, sleep quality and everyday productivity. Divided by treatment, needs were rated differently, recommending individualized and targeted choice of therapy. CONCLUSION Age and gender stratify patient needs. Women showed higher expectations and rated specific needs in psoriasis treatment higher than men. Analyzing the patient needs on an individual level will facilitate shared decisions by patient and physician in finding the optimal personalized treatment. This article is protected by copyright. All rights reserved.

IL-26 is an antimicrobial protein secreted by Th17 cells that has the ability to directly kill extracellular bacteria. To ascertain whether IL-26 contributes to host defense against intracellular bacteria, we studied leprosy, caused by the obligate intracellular pathogen Mycobacterium leprae, as a model. Analysis of leprosy skin lesions by gene expression profiling and immunohistology revealed that IL-26 was more strongly expressed in lesions from the self-limited tuberculoid compared with expression in progressive lepromatous patients. IL-26 directly bound to M. leprae in axenic culture and reduced bacteria viability. Furthermore, IL-26, when added to human monocyte-derived macrophages infected with M. leprae, entered the infected cell, colocalized with the bacterium, and reduced bacteria viability. In addition, IL-26 induced autophagy via the cytoplasmic DNA receptor stimulator of IFN genes (STING), as well as fusion of phagosomes containing bacilli with lysosomal compartments. Altogether, our data suggest that the Th17 cytokine IL-26 contributes to host defense against intracellular bacteria.

DC, through the uptake, processing, and presentation of antigen, are responsible for activation of T cell responses to defend the host against infection, yet it is not known if they can directly kill invading bacteria. Here, we studied in human leprosy, how Langerhans cells (LC), specialized DC, contribute to host defense against bacterial infection. IFN-γ treatment of LC isolated from human epidermis and infected with Mycobacterium leprae (M. leprae) activated an antimicrobial activity, which was dependent on the upregulation of the antimicrobial peptide cathelicidin and induction of autophagy. IFN-γ induction of autophagy promoted fusion of phagosomes containing M. leprae with lysosomes and the delivery of cathelicidin to the intracellular compartment containing the pathogen. Autophagy enhanced the ability of M. leprae-infected LC to present antigen to CD1a-restricted T cells. The frequency of IFN-γ labeling and LC containing both cathelicidin and autophagic vesicles was greater in the self-healing lesions vs. progressive lesions, thus correlating with the effectiveness of host defense against the pathogen. These data indicate that autophagy links the ability of DC to kill and degrade an invading pathogen, ensuring cell survival from the infection while facilitating presentation of microbial antigens to resident T cells.

Amphiphilicity in ɑ-helical antimicrobial peptides (AMPs) is recognized as a signature of potential membrane activity. Some AMPs are also strongly immunomodulatory: LL37-DNA complexes potently amplify Toll-like receptor 9 (TLR9) activation in immune cells and exacerbate autoimmune diseases. The rules governing this proinflammatory activity of AMPs are unknown. Here we examine the supramolecular structures formed between DNA and three prototypical AMPs using small angle X-ray scattering and molecular modeling. We correlate these structures to their ability to activate TLR9 and show that a key criterion is the AMP’s ability to assemble into superhelical protofibril scaffolds. These structures enforce spatially-periodic DNA organization in nanocrystalline immunocomplexes that trigger strong recognition by TLR9, which is conventionally known to bind single DNA ligands. We demonstrate that we can “knock in” this ability for TLR9 amplification in membrane-active AMP mutants, which suggests the existence of tradeoffs between membrane permeating activity and immunomodulatory activity in AMP sequences., Amphihelical antimicrobial peptides (AMPs) are bactericidal host defense factors, but their function as immunomodulators is emerging. Here the authors show that several AMPs organize DNA into periodic nanocrystals by self-assembling into superhelical protofibril scaffolds, which potentiates DNA sensing by TLR9.

Th17 cells play a critical role in the adaptive immune response against extracellular bacteria, and the possible mechanisms by which they can protect against infection are of particular interest. In this study, we describe, to our knowledge, a novel IL-1β dependent pathway for secretion of the antimicrobial peptide IL-26 from human Th17 cells that is independent of and more rapid than classical TCR activation. We find that IL-26 is secreted 3 hours after treating PBMCs with Mycobacterium leprae as compared with 48 hours for IFN-γ and IL-17A. IL-1β was required for microbial ligand induction of IL-26 and was sufficient to stimulate IL-26 release from Th17 cells. Only IL-1RI+ Th17 cells responded to IL-1β, inducing an NF-κB–regulated transcriptome. Finally, supernatants from IL-1β–treated memory T cells killed Escherichia coli in an IL-26–dependent manner. These results identify a mechanism by which human IL-1RI+ “antimicrobial Th17 cells” can be rapidly activated by IL-1β as part of the innate immune response to produce IL-26 to kill extracellular bacteria.

Background: Melanocytic tumours which colonise basal cell carcinomas (BCC) may be considered as either lentigo maligna (LM) (in situ) or invasive melanomas. Objectives: To highlight the diagnostic approach and long-term prognosis of LM which colonises BCC. Materials and methods: Using Satter et al.’s classification, we identified a case of BCC colonised by LM and reviewed similar cases in the literature with long-term follow-up. Results: In the absence of melanocytic extension beyond the lamina propria of the BCC compartment, mixed tumours may be considered as LM colonising the BCC, allowing for less invasive surgery. The absence of long-term relapse in our short series supports this diagnosis, rather than invasive melanomas. Conclusion: Our case report, review of the literature, and series follow-up illustrate the most recent assessment of melanocytic/BCC tumours, and guide the physician and the pathologist in their recognition and classification, thus allowing them to make the most appropriate therapeutic decisions.

Psoriasis vulgaris is a common, chronic inflammatory skin disease with a prevalence of 1.5-2% in Western industrialized countries. A relevant percentage of patients suffer from moderate-to-severe psoriasis and experience a significant reduction in quality of life. The choice of an adequate therapy could help to prevent disease and exacerbation of comorbidity, which could increase quality of life, avoid hospitalization and avoid reduction of working days. The present guidelines are focused on the initiation and management of systemic therapies in cases of moderate-to-severe plaque-type psoriasis in adults to optimize treatment response, adherence and quality of life. This first version of the Swiss S1 guidelines presents therapeutic recommendations which are based on a systematic literature search as well as an informal expert consensus of dermatologists in Switzerland.

Atopic dermatitis (AD) is the most common inflammatory dermatitis for which molecular research is currently extending. Mostly mediated by helper T lymphocytes type 2 (Th2), it seems that Th22 and Th17 can also be involved on a smaller scale. An IL-4/IL-13 inhibitor, key cytokines of the Th2 pathway, has recently been recognized as a new treatment for AD and has opened the field to multiple clinical trials for other selective immunosuppressants such as biologics and small molecules. These advances make us hope for the development of more effective and better-tolerated treatments than conventional immunosuppressants. In addition, they promise to advance the knowledge of this complex inflammatory pathology and its clinical subtypes.La dermatite atopique (DA) est la dermatose inflammatoire la plus fréquente pour laquelle la recherche moléculaire est actuellement en plein essor. Majoritairement médiées par les lymphocytes T helper de type 2 (Th2), il semblerait que les voies Th22 et Th17 puissent également être impliquées à moindre échelle. Un inhibiteur des cytokines IL-4/IL-13, cytokines clés de la voie Th2, a récemment été reconnu comme un nouveau traitement de la DA et a ouvert le champ à de multiples essais cliniques pour d’autres immunosuppresseurs sélectifs que sont les biologiques et les petites molécules. Ces avancées nous font espérer le développement de traitements plus efficaces et mieux tolérés que les immunosuppresseurs classiques. De plus, elles promettent de faire avancer l’élucidation de cette pathologie inflammatoire complexe et de ses sous-types cliniques.

Over the last decade, the management of psoriasis has witnessed a paradigm shift. Thanks to the increasing knowledge about the pathogenesis of psoriasis, targeted treatments with monoclonal antibodies have been developed. These antibodies, which target the pathogenic TNF/IL-23/IL-17-pathway, were shown to be safe and efficacious in the management of most patients with moderate to severe chronic plaque psoriasis. Recently, molecular and genetic studies in pustular and erythrodermic psoriasis have identified additional inflammatory pathways, providing evidence that psoriasis is a heterogeneous disease and highlighting the requirement for personalized disease characterization for treatment optimization. In this article, we will review these advances and provide an update on the currently available treatment arsenal. We discuss the efficacy and safety profile of these individual therapeutic agents and describe their use in special indications. We will also describe the current understanding of psoriasis as a systemic disease associated with multiple comorbidities and illustrate its impact in the management of psoriatic patients. Finally, we discuss ongoing therapeutic developments as well as unmet needs and future perspectives in the field of psoriasis.

Comment in : Plasmacytoid dendritic cells: Division of labour./ Bird L. Nat Rev Immunol. 2017 Dec 22;18(1):2-3. doi: 10.1038/nri.2017.153. PMID: 29269763; International audience; Innate immune cells adjust to microbial and inflammatory stimuli through a process termed environmental plasticity, which links a given individual stimulus to a unique activated state. Here, we report that activation of human plasmacytoid predendritic cells (pDCs) with a single microbial or cytokine stimulus triggers cell diversification into three stable subpopulations (P1-P3). P1-pDCs (PD-L1+CD80-) displayed a plasmacytoid morphology and specialization for type I interferon production. P3-pDCs (PD-L1-CD80+) adopted a dendritic morphology and adaptive immune functions. P2-pDCs (PD-L1+CD80+) displayed both innate and adaptive functions. Each subpopulation expressed a specific coding- and long-noncoding-RNA signature and was stable after secondary stimulation. P1-pDCs were detected in samples from patients with lupus or psoriasis. pDC diversification was independent of cell divisions or preexisting heterogeneity within steady-state pDCs but was controlled by a TNF autocrine and/or paracrine communication loop. Our findings reveal a novel mechanism for diversity and division of labor in innate immune cells.

Interleukin 17-producing helper T cells (T(H)17 cells) have a major role in protection against infections and in mediating autoimmune diseases, yet the mechanisms involved are incompletely understood. We found that interleukin 26 (IL-26), a human T(H)17 cell-derived cytokine, is a cationic amphipathic protein that kills extracellular bacteria via membrane-pore formation. Furthermore, T(H)17 cell-derived IL-26 formed complexes with bacterial DNA and self-DNA released by dying bacteria and host cells. The resulting IL-26-DNA complexes triggered the production of type I interferon by plasmacytoid dendritic cells via activation of Toll-like receptor 9, but independently of the IL-26 receptor. These findings provide insights into the potent antimicrobial and proinflammatory function of T(H)17 cells by showing that IL-26 is a natural human antimicrobial that promotes immune sensing of bacterial and host cell death.

Psoriasis is a chronic autoimmune skin disease affecting approximately 2 % of the population with a major psychosocial and socioeconomic impact. A causal therapy leading to permanent cure is not available, and current treatments only lead to limited amelioration, and therefore new therapeutic targets need to be identified. Recent works demonstrated a predominant role of T

Background: Psoriasis is accepted as a multisystemic disease with several important systemic manifestations. Thus, underlying comorbidities have to be taken into account in the choice of treatment. Objective: To explore the role of anti-TNF therapy in the treatment of psoriasis in a patient with acute-on-chronic pancreatitis. Methods: Here, we present the case of a 75-year-old patient with severe psoriasis also suffering from chronic alcohol-induced pancreatitis with recurrent acute flares. A recent life-threatening episode of acute pancreatitis and ischemic liver precluded the reintroduction of methotrexate. Cyclosporine was also excluded as it has been reported to induce acute pancreatitis. Thus, an anti-TNF treatment was initiated in close collaboration with a gastroenterologist. Results: A year after starting anti-TNF therapy the patient continues to show complete clinical remission of his psoriasis. No side effects, particularly no bacterial infections, were reported. No relapses of the patient's underlying chronic pancreatitis were observed throughout the entire treatment with regular clinical and laboratory monitoring, suggesting that chronic pancreatitis is not per se a contraindication for anti-TNF therapy. Conclusion: This case study opens the way for further questioning on the role of TNF in the pathogenesis of chronic and acute pancreatitis and the use of anti-TNF therapy in its treatment.

The endoplasmic reticulum kinase inositol-requiring enzyme 1 (IRE1) and its downstream target X-box-binding protein 1 (XBP1) drive B-cell differentiation toward plasma cells and have been shown to contribute to multiple myeloma development; yet, little is known of the role of this pathway in diffuse large B-cell lymphoma (DLBCL). Here, we show that in the germinal center B-cell-like (GCB) DLBCL subtype, IRE1 expression is reduced to a level that prevents XBP1 activation. Gene expression profiles indicated that, in GCB DLBCL cancer samples, expression of IRE1 messenger RNA was inversely correlated with the levels and activity of the epigenetic repressor, histone methyltransferase enhancer of zeste homolog 2 (EZH2). Correspondingly, in GCB-derived cell lines, the IRE1 promoter carried increased levels of the repressive epigenetic mark histone 3 lysine 27 trimethylation. Pharmacological inhibition of EZH2 erased those marks and restored IRE1 expression and function in vitro and in vivo. Moreover, reconstitution of the IRE1-signaling pathway, by expression of the XBP1-active form, compromised GCB DLBCL tumor growth in a mouse xenograft cancer model. These findings indicate that IRE1-XBP1 downregulation distinguishes GCB DLBCL from other DLBCL subtypes and contributes to tumor growth.

Background: The Swiss psoriasis registry SDNTT (Swiss Dermatology Network for Targeted Therapies) records the long-term safety and effectiveness of systemic treatment regimens for psoriasis. Patients and Methods: Patients with moderate to severe psoriasis are included in the SDNTT when treatment with a conventional systemic agent or biologic is initiated that was not previously used by the respective patient. Patients are followed over a 5-year period. Clinical data are obtained every 3-6 months using standardized case report forms. Here, baseline data and follow-up data for 1 year of patients included from October 2011 until December 2014 were analyzed. Results: Within 39 months, 323 patients from 7 tertiary dermatology centers in Switzerland were recruited in the SDNTT; 165 patients received biologics and 158 conventional systemic therapies. Patients treated with biologics had a significantly higher severity (PASI 11.3 vs. 9.2, BSA 15.6 vs.11.9, psoriatic arthritis 36.4 vs. 10.8%; p ≤ 0.005, p ≤ 0.013, p ≤ 0.001) and a longer duration of illness (19.2 vs. 14.4 years, p ≤ 0.003) compared to patients starting a conventional systemic treatment. PASI reduction was satisfying in both treatment groups, with 60.6% of patients treated with biologics achieving PASI75 after 1 year compared to 54.2% of patients receiving conventional systemic drugs (nonsignificant). On average, the drug survival in patients receiving a biologic therapy was significantly longer than those receiving conventional systemic treatments (30.5 vs. 19.2 months, p ≤ 0.001). Conclusions: In the real-world setting of a prospective national therapy registry, the application of current therapeutic guidelines for patients with moderate to severe psoriasis resulted in a PASI reduction of approximately 70% within the first year of treatment, but current therapeutic targets of PASI75 and PASI90 were reached in only 58 and 36% of patients, respectively, at 1 year, highlighting a gap in efficacy between selective clinical trials and the real-world setting.

Activation of the elongation factor 2 kinase (eEF2K) leads to the phosphorylation and inhibition of the elongation factor eEF2, reducing mRNA translation rates. Emerging evidence indicates that the regulation of factors involved in protein synthesis may be critical for controlling diverse biological processes including cancer progression. Here we show that inhibitors of the HIV aspartyl protease (HIV‐PIs), nelfinavir in particular, trigger a robust activation of eEF2K leading to the phosphorylation of eEF2. Beyond its anti‐viral effects, nelfinavir has antitumoral activity and promotes cell death. We show that nelfinavir‐resistant cells specifically evade eEF2 inhibition. Decreased cell viability induced by nelfinavir is impaired in cells lacking eEF2K. Moreover, nelfinavir‐mediated anti‐tumoral activity is severely compromised in eEF2K‐deficient engrafted tumors in vivo. Our findings imply that exacerbated activation of eEF2K is detrimental for tumor survival and describe a mechanism explaining the anti‐tumoral properties of HIV‐PIs.

Background: Randomized controlled trials have shown the efficacy of systemic treatments in moderate-to-severe psoriasis. Clinical outcomes in psoriasis patients under real-world conditions are less well understood. Objective: This study compared Psoriasis Area and Severity Index (PASI) and Dermatological Life Quality Index (DLQI) improvement in all psoriasis patients registered in the Swiss Dermatology Network for Targeted Therapies. We asked whether outcomes differed between 4 treatment strategies, namely biologic monotherapy versus conventional systemic monotherapy, versus combined biologic and conventional systemic drugs, and versus therapy adaptation (switching from one type to another). Methods: PASI and DLQI within 1 year after onset of systemic treatment, measured at 3, 6, and 12 months, were compared among the 4 groups using generalized linear mixed-effects models. Results: Between March 2011 and December 2014, 334 patients were included; 151 received conventional systemic therapeutics, 145 biologics, 13 combined treatment, and 25 had a therapy adaptation. With regard to the absolute PASI, neither the biologic cohort nor the combined treatment cohort significantly differed from the conventional systemic therapeutics cohort. The odds of reaching PASI90 was significantly increased with combined therapy compared to conventional systemic therapeutics (p = 0.043) and decreased with a higher body mass index (p = 0.041). At visits 3 and 4, the PASI was generally lower than at visit 2 (visit 3 vs. visit 2, p = 0.0019; visit 4 vs. visit 2, p < 0.001). After 12 months, patients with biologic treatment had a significantly lower DLQI than those with conventional systemic therapeutics (p = 0.001). Conclusion: This study suggests that after 1 year of treatment, biologics are superior in improving the subjective disease burden compared to conventional systemic drugs.

The intracellular location of nucleic acid sensors prevents recognition of extracellular self-DNA released by dying cells. However, on forming a complex with the endogenous antimicrobial peptide LL37, extracellular DNA is transported into endosomal compartments of plasmacytoid dendritic cells, leading to activation of Toll-like receptor-9 and induction of type I IFNs. Whether LL37 also transports self-DNA into nonplasmacytoid dendritic cells, leading to type I IFN production via other intracellular DNA receptors is unknown. Here we found that LL37 very efficiently transports self-DNA into monocytes, leading the production of type I IFNs in a Toll-like receptor-independent manner. This type I IFN induction was mediated by double-stranded B form DNA, regardless of its sequence, CpG content, or methylation status, and required signaling through the adaptor protein STING and TBK1 kinase, indicating the involvement of cytosolic DNA sensors. Thus, our study identifies a novel link between the antimicrobial peptides and type I IFN responses involving DNA-dependent activation of cytosolic sensors in monocytes.

Epithelial ovarian cancer (EOC) is the fifth most common cause of cancer death among women. Despite its immunogenicity, effective antitumor responses are limited, due, in part, to the presence of forkhead box protein 3–positive (Foxp3+) T regulatory (Treg) cells in the tumor microenvironment. However, the mechanisms that regulate the accumulation and the suppressive function of these Foxp3+ Treg cells are poorly understood. Here, we found that the majority of Foxp3+ Treg cells accumulating in the tumor microenvironment of EOCs belong to the subset of Foxp3+ Treg cells expressing inducible costimulator (ICOS). The expansion and the suppressive function of these cells were strictly dependent on ICOS-L costimulation provided by tumor plasmacytoid dendritic cells (pDC). Accordingly, ICOS+ Foxp3+ Treg cells were found to localize in close vicinity of tumor pDCs, and their number directly correlated with the numbers of pDCs in the tumors. Furthermore, pDCs and ICOS+ Foxp3+ Treg cells were found to be strong predictors for disease progression in patients with ovarian cancer, with ICOS+ Treg cell subset being a stronger predictor than total Foxp3+ Treg cells. These findings suggest an essential role for pDCs and ICOS-L in immunosuppression mediated by ICOS+ Foxp3+ Treg cells, leading to tumor progression in ovarian cancer. Cancer Res; 72(20); 5240–9. ©2012 AACR.

Plasmacytoid dendritic cells (pDCs) were first described as interferon-producing cells and, for many years, their overlapping characteristics with both lymphocytes and classical dendritic cells (cDCs) created confusion over their exact ontogeny. In this Viewpoint article, Nature Reviews Immunology asks five leaders in the field to discuss their thoughts on the development and functions of pDCs — do these cells serve mainly as a major source of type I interferons or do they also make other important contributions to immune responses?

Cutaneous injury in mice drives transient TLR7- and TLR9-mediated production of type I interferon by plasmacytoid dendritic cells, which is required for re-epithelialization of the skin., Plasmacytoid dendritic cells (pDCs) are specialized type I interferon (IFN-α/β)–producing cells that express intracellular toll-like receptor (TLR) 7 and TLR9 and recognize viral nucleic acids in the context of infections. We show that pDCs also have the ability to sense host-derived nucleic acids released in common skin wounds. pDCs were found to rapidly infiltrate both murine and human skin wounds and to transiently produce type I IFNs via TLR7- and TLR9-dependent recognition of nucleic acids. This process was critical for the induction of early inflammatory responses and reepithelization of injured skin. Cathelicidin peptides, which facilitate immune recognition of released nucleic acids by promoting their access to intracellular TLR compartments, were rapidly induced in skin wounds and were sufficient but not necessary to stimulate pDC activation and type I IFN production. These data uncover a new role of pDCs in sensing tissue damage and promoting wound repair at skin surfaces.

Clinical manifestations of lichenoid tissue reactions are heterogenous and include the cutaneous lupus erythematosus and lichen planus. Lichenoid tissue reactions are characterized by epidermal basal-cell damage and a variable subepithelial inflammatory infiltrate including cytotoxic T(H)1 cells and plasmacytoid dendritic cells. Here, we summarize the current knowledge of the role of chemokines in the pathophysiology of lichenoid tissue reactions and propose mechanisms by which recruitment and local activation of cytotoxic T(H)1 cells and plasmacytoid dendritic cells may result in initiation and amplification of lichen planus and cutaneous lupus erythematosus.

Plasmacytoid dendritic cells (pDCs) are important mediators of antiviral immunity through their ability to produce large amounts of type I interferons (IFNs) on viral infection. This function of pDCs is linked to their expression of Toll-like receptor 7 (TLR7) and TLR9, which sense viral nucleic acids within the early endosomes. Exclusion of self nucleic acids from TLR-containing early endosomes normally prevents pDC responses to them. However, in some autoimmune diseases, self nucleic acids can be modified by host factors and gain entrance to pDC endosomes, where they activate TLR signalling. Several pDC receptors negatively regulate type I IFN responses by pDCs during viral infection and for normal homeostasis.

SummaryPrevious studies suggest that thymus produces a homogenous population of natural regulatory T (Treg) cells that express a transcriptional factor FOXP3 and control autoimmunity through a cell-contact-dependent mechanism. We found two subsets of FOXP3+ natural Treg cells defined by the expression of the costimulatory molecule ICOS in the human thymus and periphery. Whereas the ICOS+FOXP3+ Treg cells used interleukin-10 to suppress dendritic cell function and transforming growth factor (TGF)-β to suppress T cell function, the ICOS−FOXP3+ Treg cells used TGF-β only. The survival and proliferation of the two subsets of Treg cells were differentially regulated by signaling through ICOS or CD28, respectively. We suggest that the selection of natural Treg cells in thymus is coupled with Treg cell differentiation into two subsets imprinted with different cytokine expression potentials and use both cell-contact-dependent and independent mechanisms for immunosuppression in periphery.

Although there is evidence for distinct roles of myeloid dendritic cells (DCs [mDCs]) and plasmacytoid pre-DCs (pDCs) in regulating T cell–mediated adaptive immunity, the concept of functional DC subsets has been questioned because of the lack of a molecular mechanism to explain these differences. In this study, we provide direct evidence that maturing mDCs and pDCs express different sets of molecules for T cell priming. Although both maturing mDCs and pDCs upregulate the expression of CD80 and CD86, only pDCs upregulate the expression of inducible costimulator ligand (ICOS-L) and maintain high expression levels upon differentiation into mature DCs. High ICOS-L expression endows maturing pDCs with the ability to induce the differentiation of naive CD4 T cells to produce interleukin-10 (IL-10) but not the T helper (Th)2 cytokines IL-4, -5, and -13. These IL-10–producing T cells are T regulatory cells, and their generation by ICOS-L is independent of pDC-driven Th1 and Th2 differentiation, although, in the later condition, some contribution from endogenous IL-4 cannot be completely ruled out. Thus, in contrast to mDCs, pDCs are poised to express ICOS-L upon maturation, which leads to the generation of IL-10–producing T regulatory cells. Our findings demonstrate that mDC and pDCs are intrinsically different in the expression of costimulatory molecules that drive distinct types of T cell responses.

We examine how the interferon production of plasmacytoid dendritic cells is amplified by the self-assembly of liquid-crystalline antimicrobial peptide/DNA complexes. These specialized dendritic cells are important for host defense because they quickly release large quantities of type I interferons in response to infection. However, their aberrant activation is also correlated with autoimmune diseases such as psoriasis and lupus. In this review, we will describe how polyelectrolyte self-assembly and the statistical mechanics of multivalent interactions contribute to this process. In a more general compass, we provide an interesting conceptual corrective to the common notion in molecular biology of a dichotomy between specific interactions and non-specific interactions, and show examples where one can construct exquisitely specific interactions using non-specific interactions.

Type I IFNs (IFN-I) are key innate mediators that create a profound antiviral state and orchestrate the activation of almost all immune cells. Plasmacytoid dendritic cells (pDCs) are the most powerful IFN-I–producing cells and play important roles during viral infections, cancer, and autoimmune diseases. By comparing gene expression profiles of murine pDCs and conventional DCs, we found that CD28, a prototypic T cell stimulatory receptor, was highly expressed in pDCs. Strikingly, CD28 acted as a negative regulator of pDC IFN-I production upon TLR stimulation but did not affect pDC survival or maturation. Importantly, cell-intrinsic CD28 expression restrained pDC (and systemic) IFN-I production during in vivo RNA and DNA viral infections, limiting antiviral responses and enhancing viral growth early after exposure. Finally, CD28 also downregulated IFN-I response upon skin injury. Our study identified a new pDC regulatory mechanism by which the same CD28 molecule that promotes stimulation in most cells that express it is co-opted to negatively regulate pDC IFN-I production and limit innate responses.

PASS syndrome is a rare inflammatory disease characterized by a chronic-relapsing course of pyoderma gangrenosum, acne vulgaris, hidradenitis suppurativa and ankylosing spondylitis. Here, we describe a case of a patient with spontaneously recurrent purulent skin lesions along with seronegative spondylarthritis consistent with the PASS syndrome. During his disease exacerbation, the patient displayed episodes of fever along with elevated serum levels of interleukin (IL)-1β. Skin lesions were characterized by sterile neutrophilic infiltrates and showed a rapid response to the IL-1 receptor antagonist anakinra (Kineret®) consistent with the autoinflammatory nature of this disease. However, unlike other autoinflammatory diseases such as PAPA and PAPASH, we did not find mutations in the gene PSTPIP1, raising the possibility that other specific mutations in the IL-1 pathway may be involved.