Single cell sequencing delineates T-cell clonality and pathogenesis of the parapsoriasis disease group.

BACKGROUND: Mycosis fungoides (MF), the most common cutaneous T-cell lymphoma, is often underdiagnosed in early stages due to similarities with benign dermatoses such as atopic dermatitis (AD). Furthermore, the delineation from so-called "parapsoriasis en plaque," a disease that can appear either in a small- or large-plaque form, is still controversial. OBJECTIVE: To characterize the parapsoriasis disease spectrum. METHODS: We performed single-cell RNA sequencing of skin biopsies from patients within the parapsoriasis-to-early-stage MF spectrum, stratified for small and large plaques, and compared them to AD, psoriasis and healthy control skin. RESULTS: 6 out of 8 large-plaque lesions harbored either an expanded alpha/beta or gamma/delta T-cell clone with downregulation of CD7 expression, consistent with a diagnosis of early-stage MF. By contrast, 6 out of 7 small-plaque lesions were polyclonal in nature thereby lacking a lymphomatous phenotype, and also revealed a less inflammatory microenvironment than early-stage MF or AD. Of note, polyclonal small- and large-plaque lesions characteristically harbored a population of NPY+ innate lymphoid cells and displayed a stromal signature of complement upregulation and antimicrobial hyperresponsiveness in fibroblasts and sweat gland cells, respectively. These conditions were clearly distinct from AD or psoriasis, which uniquely harbored CD3+CRTH2+ IL13-expressing "Th2A" cells or strong type 17 inflammation, respectively. CONCLUSION: These data position polyclonal small- and large-plaque dermatitis lesions as a separate disease entity, that characteristically harbors a so far undescribed ILC population. We thus propose the new term "polyclonal parapsoriasis en plaque" to this kind of lesions, as they can be clearly differentiated from early and advanced-stage MF, psoriasis and AD on several cellular and molecular levels.

Consensus Recommendations for the Management of Atopic Dermatitis in the United Arab Emirates.

Atopic dermatitis often begins in infancy and follows a chronic course of exacerbations and remissions. The etiology is complex and involves numerous factors that contribute to skin barrier defect and inflammation. In the Middle East, the burden of atopic dermatitis is understudied. Epidemiological data specific to the Gulf region are scarce but reveal a prevalence of up to about 40% in the United Arab Emirates. Region-specific factors, such as the climate and the frequency of consanguineous marriages, may affect atopic dermatitis incidence, prevalence, and evolution over time. A panel of experts predominantly from the United Arab Emirates analyzed the evidence from published guidelines, and considered expert guidance and local treatment practices to develop clear recommendations for the management of atopic dermatitis in the United Arab Emirates. They encourage a systematic approach for the diagnosis and treatment, using disease severity scores and quality-of-life measurement tools. Treatment recommendations take into consideration both established therapies and the approved systemic biologics dupilumab and tralokinumab, and the Janus kinase inhibitors baricitinib, upadacitinib, and abrocitinib.

Subcutaneous adipose tissue: Implications in dermatological diseases and beyond.

Subcutaneous adipose tissue (SAT) is the deepest component of the three-layered cutaneous integument. While mesenteric adipose tissue-based immune processes have gained recognition in the context of the metabolic syndrome, SAT has been traditionally considered primarily for energy storage, with less attention to its immune functions. SAT harbors a reservoir of immune and stromal cells that significantly impact metabolic and immunologic processes not only in the skin, but even on a systemic level. These processes include wound healing, cutaneous and systemic infections, immunometabolic, and autoimmune diseases, inflammatory skin diseases, as well as neoplastic conditions. A better understanding of SAT immune functions in different processes, could open avenues for novel therapeutic interventions. Targeting SAT may not only address SAT-specific diseases but also offer potential treatments for cutaneous or even systemic conditions. This review aims to provide a comprehensive overview on SAT's structure and functions, highlight recent advancements in understanding its role in both homeostatic and pathological conditions within and beyond the skin, and discuss the main questions for future research in the field.

Development of a Cellular Assay as a Personalized Model for Testing Chronic Wound Therapeutics.

Exudates of nonhealing wounds contain drivers of pathogenicity. We utilized >800 exudates from nonhealing and healing wounds of diverse etiologies, collected by 3 different methods, to develop a wound-specific, cell-based functional biomarker assay. Human dermal fibroblast proliferation served as readout to (i) differentiate between healing and nonhealing wounds, (ii) follow the healing process of individual patients, and (iii) assess the effects of therapeutics for chronic wounds ex vivo. We observed a strong correlation between wound chronicity and inhibitory effects of individual exudates on fibroblast proliferation, with good diagnostic sensitivity (76-90%, depending on the sample collection method). Transition of a clinically nonhealing to a healing phenotype restored fibroblast proliferation and extracellular matrix formation while reducing inflammatory cytokine production. Transcriptional analysis of fibroblasts exposed to ex vivo nonhealing wound exudates revealed an induction of inflammatory cytokine and chemokine pathways and the unfolded protein response, indicating that these changes may contribute to the pathology of nonhealing wounds. Testing the wound therapeutics, PDGF and silver sulfadiazine, yielded responses in line with clinical experience and indicates the usefulness of the assay to search for and profile new therapeutics.

IgE Depletion with Ligelizumab Does Not Significantly Improve Clinical Symptoms in Patients with Moderate-to-Severe Atopic Dermatitis.

BACKGROUND: The value, if any, of anti-IgE approaches in the treatment of atopic dermatitis has not been fully clarified. Studies using the anti-IgE omalizumab have yielded conflicting results. OBJECTIVE: Antibodies with an IgE-suppressive capacity stronger than omalizumab might be more efficacious. STUDY DESIGN: We assessed the safety and efficacy of the high-affinity anti-IgE antibody ligelizumab (280 mg, subcutaneous, every other week) in 22 adult patients with moderate-to-severe atopic dermatitis in a placebo and active (cyclosporine A) controlled, randomized, multicenter, double-blind clinical trial for 12 weeks. RESULTS: We found that ligelizumab treatment resulted in either complete (patients with baseline IgE < 1,500 IU/ml) or partial (baseline IgE > 1,500 IU/ml) suppression of serum and cell-bound IgE as well as of allergic skin prick tests. On the other hand, ligelizumab-as opposed to cyclosporine A-was not significantly superior to placebo in inducing Eczema Area and Severity Index 50 response or significantly reducing pruritus and sleep disturbance. Interestingly though, patients with high baseline IgE exhibited a slightly but not significantly better treatment response than those with low baseline IgE. CONCLUSION: Our study shows that an immunologically efficacious anti-IgE approach is not clearly superior to placebo in treating atopic dermatitis. Larger studies are needed to determine whether certain patient subgroups may benefit from this strategy. TRIAL REGISTRATION: The study was registered in 2011 at clinicaltrialsregister.eu, EudraCT Number 2011-002112-84.

Topical niclosamide (ATx201) reduces Staphylococcus aureus colonization and increases Shannon diversity of the skin microbiome in atopic dermatitis patients in a randomized, double-blind, placebo-controlled Phase 2 trial.

BACKGROUND: In patients with atopic dermatitis (AD), Staphylococcus aureus frequently colonizes lesions and is hypothesized to be linked to disease severity and progression. Treatments that reduce S. aureus colonization without significantly affecting the skin commensal microbiota are needed. METHODS AND FINDINGS: In this study, we tested ATx201 (niclosamide), a small molecule, on its efficacy to reduce S. aureus and propensity to evolve resistance in vitro. Various cutaneous formulations were then tested in a superficial skin infection model. Finally, a Phase 2 randomized, double-blind and placebo-controlled trial was performed to investigate the impact of ATx201 OINTMENT 2% on S. aureus colonization and skin microbiome composition in patients with mild-to-severe AD (EudraCT:2016-003501-33). ATx201 has a narrow minimal inhibitory concentration distribution (.125-.5 µg/ml) consistent with its mode of action - targeting the proton motive force effectively stopping cell growth. In murine models, ATx201 can effectively treat superficial skin infections of methicillin-resistant S. aureus. In a Phase 2 trial in patients with mild-to-severe AD (N = 36), twice-daily treatment with ATx201 OINTMENT 2% effectively reduces S. aureus colonization in quantitative colony forming unit (CFU) analysis (primary endpoint: 94.4% active vs. 38.9% vehicle success rate, p = .0016) and increases the Shannon diversity of the skin microbiome at day 7 significantly compared to vehicle. CONCLUSION: These results suggest that ATx201 could become a new treatment modality as a decolonizing agent.

Safety of Brodalumab in Plaque Psoriasis: Integrated Pooled Data from Five Clinical Trials.

Brodalumab is approved for treatment of moderate-to-severe plaque psoriasis. Here, we assess the safety profile of brodalumab using pooled safety data from 5 phase II/III trials of brodalumab 140 mg or 210 mg. In total, 4,464 patients received brodalumab, representing 8,891.6 patient-years of exposure. During the placebo-controlled 12-week induction period, rates of serious adverse events per 100 patient-years were 10.8 and 9.6 (brodalumab 140 mg and 210 mg, respectively) vs 4.3 and 6.5 (ustekinumab and placebo, respectively); infections were the most frequent serious adverse event. Rates of serious adverse events during the comparator-controlled 52-week period were 14.4, 10.2 and 8.3 per 100 patient-years for brodalumab 210 mg, brodalumab 140 mg, and ustekinumab, respectively. Brodalumab was not associated with increased risks of malignancy, major adverse cardiac events, suicidal ideation and behaviour, or fatal events. Overall, brodalumab demonstrated an acceptable safety profile in short- and long-term treatment.

Single-cell analysis reveals innate lymphoid cell lineage infidelity in atopic dermatitis.

BACKGROUND: Although ample knowledge exists about phenotype and function of cutaneous T lymphocytes, much less is known about the lymphocytic components of the skin's innate immune system. OBJECTIVE: To better understand the biologic role of cutaneous innate lymphoid cells (ILCs), we investigated their phenotypic and molecular features under physiologic (normal human skin [NHS]) and pathologic (lesional skin of patients with atopic dermatitis [AD]) conditions. METHODS: Skin punch biopsies and reduction sheets as well as blood specimens were obtained from either patients with AD or healthy individuals. Cell and/or tissue samples were analyzed by flow cytometry, immunohistochemistry, and single-cell RNA sequencing or subjected to in vitro/ex vivo culture. RESULTS: Notwithstanding substantial quantitative differences between NHS and AD skin, we found that the vast majority of cutaneous ILCs belong to the CRTH2+ subset and reside in the upper skin layers. Single-cell RNA sequencing of cutaneous ILC-enriched cell samples confirmed the predominance of biologically heterogeneous group 2 ILCs and, for the first time, demonstrated considerable ILC lineage infidelity (coexpression of genes typical of either type 2 [GATA3 and IL13] or type 3/17 [RORC, IL22, and IL26] immunity within individual cells) in lesional AD skin, and to a much lesser extent, in NHS. Similar events were demonstrated in ILCs from skin explant cultures and in vitro expanded ILCs from the peripheral blood. CONCLUSION: These findings support the concept that instead of being a stable entity with well-defined components, the skin immune system consists of a network of highly flexible cellular players that are capable of adjusting their function to the needs and challenges of the environment.

Delayed antiretroviral therapy in HIV-infected individuals leads to irreversible depletion of skin- and mucosa-resident memory T cells.

People living with HIV (PLWH) are at increased risk for developing skin and mucosal malignancies despite systemic reconstitution of CD4+ T cells upon antiretroviral therapy (ART). The underlying mechanism of chronic tissue-related immunodeficiency in HIV is unclear. We found that skin CD4+ tissue-resident memory T (Trm) cells were depleted after HIV infection and replenished only upon early ART initiation. TCR clonal analysis following early ART suggested a systemic origin for reconstituting CD4+ Trm cells. Single-cell RNA sequencing in PLWH that received late ART treatment revealed a loss of CXCR3+ Trm cells and a tolerogenic skin immune environment. Human papilloma virus-induced precancerous lesion biopsies showed reduced CXCR3+ Trm cell frequencies in the mucosa in PLWH versus HIV- individuals. These results reveal an irreversible loss of CXCR3+ Trm cells confined to skin and mucosa in PLWH who received late ART treatment, which may be a precipitating factor in the development of HPV-related cancer.

Single-cell RNA sequencing reveals markers of disease progression in primary cutaneous T-cell lymphoma.

BACKGROUND: In early-stage mycosis fungoides (MF), the most common primary cutaneous T-cell lymphoma, limited skin involvement with patches and plaques is associated with a favorable prognosis. Nevertheless, approximately 20-30% of cases progress to tumors or erythroderma, resulting in poor outcome. At present, factors contributing to this switch from indolent to aggressive disease are only insufficiently understood. METHODS: In patients with advanced-stage MF, we compared patches with longstanding history to newly developed plaques and tumors by using single-cell RNA sequencing, and compared results with early-stage MF as well as nonlesional MF and healthy control skin. RESULTS: Despite considerable inter-individual variability, lesion progression was uniformly associated with downregulation of the tissue residency markers CXCR4 and CD69, the heat shock protein HSPA1A, the tumor suppressors and immunoregulatory mediators ZFP36 and TXNIP, and the interleukin 7 receptor (IL7R) within the malignant clone, but not in benign T cells. This phenomenon was not only found in conventional TCR-αß MF, but also in a case of TCR-γδ MF, suggesting a common mechanism across MF subtypes. Conversely, malignant cells in clinically unaffected skin from MF patients showed upregulation of these markers. CONCLUSIONS: Our data reveal a specific panel of biomarkers that might be used for monitoring MF disease progression. Altered expression of these genes may underlie the switch in clinical phenotype observed in advanced-stage MF.

Subcutaneous white adipose tissue: The deepest layer of the cutaneous immune barrier.

Mammalian skin, the outer covering of the body, is composed of three layers, i.e. the epidermis, the dermis and the subcutaneous white adipose tissue (SWAT). While the contribution of epidermis and dermis to the skin's immune function is well established, the role, if any, of SWAT in this regard has yet to be determined. Human SWAT is made up of lobules which consist mainly of adipocytes and are subdivided and separated from each other by vascularized septae of connective tissue. An immunophenotypic analysis of liposuction-derived SWAT demonstrated that healthy subcutaneous fat tissue, although showing no overt signs of inflammation, harbors an indigenous system of immunocytes. As opposed to epidermis and dermis, they belong mainly to the mononuclear phagocyte lineage and, to a lesser extent, represent T-lymphocytes. Their phenotype indicates that these two major subsets of SWAT leukocytes are primarily concerned with ant-inflammatory and/or regulatory functions. It thus appears that SWAT is more than a cushion protecting against mechanical trauma, and may subserve immunomodulatory functions aimed at preventing or, at least, mitigating exaggerated immune and/or inflammatory reactions..

Long-term skin-resident memory T cells proliferate in situ and are involved in human graft-versus-host disease.

The skin contains a population of tissue-resident memory T cells (Trm) that is thought to contribute to local tissue homeostasis and protection against environmental injuries. Although information about the regulation, survival program, and pathophysiological roles of Trm has been obtained from murine studies, little is known about the biology of human cutaneous Trm Here, we showed that host-derived CD69+ αß memory T cell clones in the epidermis and dermis remain stable and functionally competent for at least 10 years in patients with allogeneic hematopoietic stem cell transplantation. Single-cell RNA sequencing revealed low expression of genes encoding tissue egress molecules by long-term persisting Trm in the skin, whereas tissue retention molecules and stem cell markers were displayed by Trm The transcription factor RUNX3 and the surface molecule galectin-3 were preferentially expressed by host T cells at the RNA and protein levels, suggesting two new markers for human skin Trm Furthermore, skin lesions from patients developing graft-versus-host disease (GVHD) showed a large number of cytokine-producing host-derived Trm, suggesting a contribution of these cells to the pathogenesis of GVHD. Together, our studies highlighted the relationship between the local human skin environment and long-term persisting Trm, which differs from murine skin. Our results also indicated that local tissue inflammation occurs through host-derived Trm after allogeneic hematopoietic stem cell transplantation.

Das subkutane weiße Fettgewebe: die unterste Etage der immunologischen Hautbarriere.

Die äußere Begrenzung des Körpers von Säugetieren, die Haut, besteht aus drei Schichten, Epidermis, Dermis und subkutanem weissem Fettgewebe (subcutaneous white adipose tissue, SWAT). Während die Epidermis und Dermis hinsichtlich ihrer Funktion als «Immunbarriere¼ eingehend charakterisiert sind, ist über das SWAT nur wenig bekannt. SWAT des Menschen setzt sich aus Läppchen zusammen, die vor allem aus Adipozyten bestehen und durch vaskularisierte Bindegewebssepten unterteilt und voneinander getrennt werden. Eine immun-phänotypische Untersuchung von durch Fettabsaugung gewonnenem SWAT zeigte, dass gesundes SWAT keine Entzündungszeichen aufweist, jedoch Immunzellen beherbergt.  Im Unterschied zur restlichen Haut handelt es sich dabei hauptsächlich um Makrophagen und, in geringerem Maße, T- Lymphozyten, deren Phänotyp darauf hinweist, dass ihnen primär anti-inflammatorische und regulierende Funktionen zukommen. SWAT besitzt also nicht nur eine mechanische, sondern möglicherweise auch immunologische Schutzfunktion, die darin besteht, überschießende Immun- sowie Entzündungsreaktionen zu verhindern oder zumindest abzumildern.

[European Guidelines (S1) on the use of high-dose intravenous immunoglobulin in dermatology]. / Europäische Leitlinien (S1) für die Verwendung von hoch dosierten intravenösen Immunglobulinen in der Dermatologie.

BACKGROUND AND OBJECTIVES: Treatment of severe dermatological autoimmune diseases and toxic epidermal necrolysis (TEN) with high-dose intravenous immunoglobulin (IVIg) is a well-established procedure in dermatology. As treatment with IVIg is usually considered for rare clinical entities or severe cases, the use of immunoglobulin is not generally based on data from randomized controlled trials usually required for evidence-based medicine. Since the indications for the use of IVIg are rare, it is unlikely that such studies will be available in the foreseeable future. Because first-line use is limited by the high costs of IVIg, the first clinical guidelines on the use of IVIg in dermatological conditions were established in 2008 and renewed in 2011. METHODS: The European guidelines presented here were prepared by a panel of experts nominated by the European Dermatology Forum (EDF) and European Academy of Dermatology and Venereology (EADV). The guidelines were developed to update the indications for treatment currently considered effective and to summarize the evidence for the use of IVIg in dermatological autoimmune diseases and TEN. RESULTS AND CONCLUSION: The current guidelines represent consensual expert opinions and definitions on the use of IVIg reflecting current published evidence and are intended to serve as a decision-making tool for the use of IVIg in dermatological diseases.

The Validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD): The development and reliability testing of a novel clinical outcome measurement instrument for the severity of atopic dermatitis.

BACKGROUND: An Investigator Global Assessment (IGA) is recommended by health agencies for drug registration in atopic dermatitis (AD). Current IGA scales lack standardization. OBJECTIVES: To develop an IGA scale, training module, and clinical certification examination for use in AD trials; establish content validity; and assess reliability. METHODS: Expert dermatologists participated in the development of the validated IGA for AD (vIGA-ADTM). Reliability (interrater and intrarater) was assessed by 2 web-based surveys. Clinical certification for investigators consisted of a training module and examination. RESULTS: Expert consensus was achieved around a 5-point IGA scale including morphologic descriptions, and content validity was established. Survey 1 showed strong interrater reliability (Kendall's coefficient of concordance W [Kendall's W], 0.809; intraclass correlation [ICC], 0.817) and excellent agreement (weighted kappa, 0.857). Survey 2, completed 5 months after training of dermatologists, showed improvements in scale reliability (Kendall's W, 0.819; ICC, 0.852; weighted kappa, 0.889). In this study, 627 investigators completed vIGA-AD training and certification. LIMITATIONS: Ratings were assessed on photographs. CONCLUSION: A validated IGA scale and training module were developed with the intent of harmonizing assessment of disease severity in AD trials. Strong reliability and excellent agreement between assessments were observed.

Prevalence of Skin-specific Autoantibodies in HIV-infected Patients and Uninfected Controls.

Various autoantibodies are detected more frequently in HIV-infected individuals than in HIV-negative controls; however, limited data exist regarding autoimmune blistering skin diseases. Using enzyme-linked immunoassay (ELISA) and indirect immunofluore-scence, no difference in the frequency and magnitude of autoantibodies against BP180, BP230, desmoglein 1 and 3 was found between 594 HIV-infected patients and 248 uninfected controls in this cross-sectional study (16.0% vs. 11.7%, respectively, for at least one positive ELISA, p = 0.11). Interestingly, reactive syphilis serology in both HIV-infected individuals and uninfected controls was associated with positive anti-BP180 ELISA results (adjusted odds ratio (OR) 2.14, 95% confidence interval (CI) 1.07-4.29, p = 0.03 and OR 4.70, CI 1.3-16.86; p = 0.0180). Our study shows a comparably low prevalence of cutaneous autoantibodies in both HIV-infected patients and uninfected controls lacking signs of autoimmune blistering skin disease. Positive BP180 ELISA in the absence of clinical signs of bullous pemphigoid should prompt further evaluation for syphilis antibodies.