Flt3L, LIF, and IL-10 combination promotes the selective in vitro development of ESAMlow cDC2B from murine bone marrow.

The development of two conventional dendritic cells (DC) subsets (cDC1 and cDC2) and the plasmacytoid DC (pDC) in vivo and in cultures of bone marrow (BM) cells is mediated by the growth factor Flt3L. However, little is known about the factors that direct the development of the individual DC subsets. Here, we describe the selective in vitro generation of murine ESAMlow CD103- XCR1- CD172a+ CD11b+ cDC2 from BM by treatment with a combination of Flt3L, LIF, and IL-10 (collectively named as FL10). FL10 promotes common dendritic cell progenitors (CDP) proliferation in the cultures, similar to Flt3L and CDP sorted and cultured in FL10 generate exclusively cDC2. These cDC2 express the transcription factors Irf4, Klf4, and Notch2, and their growth is reduced using BM from Irf4-/- mice, but the expression of Batf3 and Tcf4 is low. Functionally they respond to TLR3, TLR4, and TLR9 signals by upregulation of the surface maturation markers MHC II, CD80, CD86, and CD40, while they poorly secrete proinflammatory cytokines. Peptide presentation to TCR transgenic OT-II cells induced proliferation and IFN-γ production that was similar to GM-CSF-generated BM-DC and higher than Flt3L-generated DC. Together, our data support that FL10 culture of BM cells selectively promotes CDP-derived ESAMlow cDC2 (cDC2B) development and survival in vitro.

Hidradenitis Suppurativa: Absence of Hyperhidrosis but Presence of a Proinflammatory Signature in Patients' Sweat.

The role of sweat glands in hidradenitis suppurativa has been largely neglected, despite the fact that its original designation, as "hidrosadénite phlegmoneuse", implied an inflammatory malfunction of the apocrine sweat glands as the underlying pathogenic driver. The aim of this study was to evaluate the role of apocrine sweat glands with respect to the proinflammatory environment of hidradenitis suppurativa. Therefore, gravimetric assessment and multiplex cytokine assays from sweat obtained from patients with hidradenitis suppurativa along with immunofluorescence cytokine/chemokine analysis of lesional apocrine glands- bearing hidradenitis suppurativa skin were performed. Gravimetric assessment of 17 patients with hidradenitis suppurativa revealed that the condition is not associated with hyperhidrosis. However, patients seem to be more affected by subjective sweating. The current data identified a complex proinflammatory signature in hidradenitis suppurativa sweat characterized by a significant upregulation of monocyte chemoattractant protein-1, interleukin-8 (CXCL8), and interferon-γ. In agreement with this, a strong in situ expression of these mediators could be observed in apocrine glands of lesional hidradenitis suppurativa skin. These data shed new light on the proinflammatory capacity of apocrine sweat glands in hidradenitis suppurativa, which may lead to reconsideration of the role of sweat glands in hidradenitis suppurativa pathology.

Ex vivo-expanded highly pure ABCB5+ mesenchymal stromal cells as Good Manufacturing Practice-compliant autologous advanced therapy medicinal product for clinical use: process validation and first in-human data.

BACKGROUND AIM: Mesenchymal stromal cells (MSCs) hold promise for the treatment of tissue damage and injury. However, MSCs comprise multiple subpopulations with diverse properties, which could explain inconsistent therapeutic outcomes seen among therapeutic attempts. Recently, the adenosine triphosphate-binding cassette transporter ABCB5 has been shown to identify a novel dermal immunomodulatory MSC subpopulation. METHODS: The authors have established a validated Good Manufacturing Practice (GMP)-compliant expansion and manufacturing process by which ABCB5+ MSCs can be isolated from skin tissue and processed to generate a highly functional homogeneous cell population manufactured as an advanced therapy medicinal product (ATMP). This product has been approved by the German competent regulatory authority to be tested in a clinical trial to treat therapy-resistant chronic venous ulcers. RESULTS: As of now, 12 wounds in nine patients have been treated with 5 × 105 autologous ABCB5+ MSCs per cm2 wound area, eliciting a median wound size reduction of 63% (range, 32-100%) at 12 weeks and early relief of pain. CONCLUSIONS: The authors describe here their GMP- and European Pharmacopoeia-compliant production and quality control process, report on a pre-clinical dose selection study and present the first in-human results. Together, these data substantiate the idea that ABCB5+ MSCs manufactured as ATMPs could deliver a clinically relevant wound closure strategy for patients with chronic therapy-resistant wounds.

Non-alcoholic fatty liver disease and psoriasis - is there a shared proinflammatory network?

Psoriasis is an immune-mediated systemic inflammatory disease that is not limited to the skin but may be associated with arthritis, cardiovascular diseases, metabolic syndrome including diabetes and obesity and, as identified more recently, non-alcoholic fatty liver disease (NAFLD) that occurs in approximately 50 % of all patients with psoriasis. NAFLD is characterized by accumulation of fat in hepatocytes in the absence of excessive alcohol consumption. Over the last two decades, NAFLD has developed to the most common chronic liver disease with an estimated prevalence of 25 % in the Western population. NAFLD ranges from non-inflammatory or bland hepatic steatosis to inflammation of hepatic tissue (non-alcoholic steatohepatitis, NASH) and consecutive liver fibrosis. It is controversial whether the underlying systemic inflammation of psoriasis is contributing to development of NAFLD or if comorbid diseases such as obesity enhance NAFLD development. Recent findings indicate that cytokine-mediated inflammation through TNFα, interleukin (IL)-6 and IL-17 might be the common link between psoriasis and NAFLD. Considering the shared inflammatory pathways, IL-17 pharmacological blockade, which is already well-established for psoriasis, may be a promising strategy to treat both psoriasis and NAFLD. Therefore, early detection of NAFLD and a better understanding of its pathophysiology in the context of the systemic inflammation in psoriasis is important with regard to individualized treatment approaches.

Metastatic Crohn's disease: an underestimated entity.

Cutaneous metastatic Crohn's disease (MCD) is a rare but challenging dermatologic manifestation of Crohn's disease. It is histologically defined as the presence of non-caseating granulomas at skin sites separated from and non-contiguous to the gastrointestinal tract. Cutaneous metastatic Crohn's disease should be distinguished from the much more frequent contiguous cutaneous manifestations of Crohn's disease that present at perianal or, less common, peristomal sites with direct extension from the intestine to the adjacent skin. Versatile clinical presentation and the fact that occurrence can predate the initial diagnosis of Crohn's disease may lead to misdiagnosis, delayed treatment and underreporting. As case numbers are small and randomized controlled studies on management are lacking, the therapeutic approach remains challenging and is often unsatisfactory. We here performed a systematic literature search identifying 264 published pediatric and adult cases of MCD and additionally report three of our own cases. Our review summarizes clinical characteristics, putative etiopathology, histologic findings, differential diagnoses and treatment options for MCD.

Current Developments in the Immunology of Psoriasis.

Psoriasis is a frequent inflammatory skin disease. Fundamental research on the pathogenesis of psoriasis has substantially increased our understanding of skin immunology, which has helped to introduce innovative and highly effective therapies. Psoriasis is a largely T lymphocyte-mediated disease in which activation of innate immune cells and pathogenic T cells result in skin inflammation and hyperproliferation of keratinocytes. B cells have thus far largely been neglected regarding their role for the pathogenesis of psoriasis. However, recent data shed light on their role in inflammatory skin diseases. Interestingly, interleukin (IL)-10-producing regulatory B cells have been assumed to ameliorate psoriasis. In this review, we will discuss the development of disease, pathogenicity, and current developments in therapeutic options. We describe different roles of T cells, B cells, and cytokines for the immunopathology and disease course of psoriasis.

Intricate Relationship Between Adaptive and Innate Immune System in Allergic Contact Dermatitis.

Allergic contact dermatitis (ACD) is a complex immunological allergic disease characterized by the interplay between the innate and adaptive immune system. Initially, the role of the innate immune system was believed to be confined to the initial sensitization phase, while adaptive immune reactions were linked with the advanced elicitation phase. However, recent data predicted a comparatively mixed and interdependent role of both immune systems throughout the disease progression. Therefore, the actual mechanisms of disease progression are more complex and interlinked. The aim of this review is to combine such findings that enhanced our understanding of the pathomechanisms of ACD. Here, we focused on the main cell types from both immune domains, which are involved in ACD, such as CD4+ and CD8+ T cells, B cells, neutrophils, and innate lymphoid cells (ILCs). Such insights can be useful for devising future therapeutic interventions for ACD.

In vivo safety profile and biodistribution of GMP-manufactured human skin-derived ABCB5-positive mesenchymal stromal cells for use in clinical trials.

BACKGROUND AIMS: Human dermal ABCB5-expressing mesenchymal stromal cells (ABCB5+ MSCs) represent a promising candidate for stem cell-based therapy of various currently uncurable diseases in several fields of regenerative medicine. We have developed and validated a method to isolate, from human skin samples, and expand ABCB5+ MSCs that meet the guideline criteria of the International Society for Cellular Therapy. We are able to process these cells into a Good Manufacturing Practice-conforming, MSC-based advanced-therapy medicinal product. METHODS: To support the development of ABCB5+ MSCs for potential therapeutic topical, intramuscular and intravenous administration, we have tested our product in a series of Good Laboratory Practice-compliant nonclinical in-vivo studies addressing all relevant aspects of biosafety, including potential long-term persistence and proliferation, distribution to nontarget tissues, differentiation into undesired cell types, ectopic tissue formation, tumor formation and local tissue reaction. RESULTS: (i) Subcutaneous application of 1 × 107 ABCB5+ MSCs/animal and intravenous application of 2 × 106 ABCB5+ MSCs/animal, respectively, to immunocompromised mice did not result in safety-relevant biodistribution, persistence or proliferation of the cells; (ii) three monthly subcutaneous injections of ABCB5+ MSCs at doses ranging from 1 × 105 to 1 × 107 cells/animal and three biweekly intravenous injections of 2 × 106 ABCB5+ MSCs/animal, respectively, to immunocompromised mice were nontoxic and revealed no tumorigenic potential; and (iii) intramuscular injection of 5 × 106 ABCB5+ MSCs/animal to immunocompromised mice was locally well tolerated. DISCUSSION: The present preclinical in vivo data demonstrate the local and systemic safety and tolerability of a novel advanced-therapy medicinal product based on human skin-derived ABCB5+ MSCs.

Sensitization to Hymenoptera venom marker allergens: Prevalence, predisposing factors, and clinical implications.

BACKGROUND: The prevalence and predisposing factors of asymptomatic sensitization to Hymenoptera venom marker allergens are largely unknown. OBJECTIVE: To evaluate sensitization profiles in a group of 490 dermatologic patients without a history of sting-induced anaphylaxis. METHODS: Clinical data were collected using a structured questionnaire; sera were tested for total IgE and specific IgE to venom preparations, recombinant venom marker allergens, inhalative allergens, and cross-reactive carbohydrate determinants. RESULTS: The lifetime prevalence of Hymenoptera stings was 85.3%. IgE rates exceeding cut-off values of 0.35 kUA /L were 17.3% for rVes v 1, 18.0% for rVes v 5, and 3.5% for rApi m 1. Median specific/total IgE ratios for the above mentioned marker allergens were 0.05%, 0.02%, and 0.00%, respectively. Marker allergen-directed sensitization was detectable in 85.5% of 138 Vespula venom-reactive sera. Of 68 bee venom-reactive participants, 23.5% were sensitized to rApi m 1 and 64.7% to any one or several of five commercially available bee venom allergens. Although double reactivity to bee and Vespula venom was clearly associated with sensitization to cross-reactive carbohydrate determinants (P < 0.001), sensitization to marker allergens of both species was detectable in most double-reactive sera (56.5%). Vespula venom marker allergen-directed sensitization was associated with recent stings (P = 0.010), large local reactions (P = 0.009), total IgE elevation (P < 0.001), and sensitization to cross-reactive carbohydrate determinants (P = 0.008). CONCLUSIONS AND CLINICAL RELEVANCE: The high sensitization rates observed in individuals without a history of sting-induced anaphylaxis as well as total IgE levels and cross-reactive carbohydrate determinant-directed reactivity as potential confounders need to be considered in any interpretation of positive test results for Hymenoptera venom marker allergens.

Becker Naevus Syndrome of the Lower Body: One Case and Review of the Literature.

Becker naevus syndrome is a rare epidermal naevus syndrome defined by the co-occurrence of a Becker naevus with various cutaneous, muscular and skeletal anomalies. In the majority of cases, abnormalities exclusively consist of ipsilateral hypoplasia of the breast, areola and/or nipple in addition to the naevus. Here, we report on a 42-year-old woman with an extensive Becker naevus reaching from the left buttock to the left calf verified on histological examination. In addition, there was marked hypoplasia of the fatty tissue of the left thigh confirmed by magnetic resonance imaging in contrast to hyperplasia of the fatty tissue of the left gluteal area. Underlying muscles and bones were not affected. There was no difference in leg lengths. In addition, we review and discuss the features of Becker naevus syndrome with emphasis on 10 reported cases with involvement of the lower body.

Hymenoptera venom immunotherapy while maintaining cardiovascular medication: safe and effective.

BACKGROUND: The hypothetical risks of cardiovascular medication during Hymenoptera venom immunotherapy (VIT) are still a matter of controversy. OBJECTIVE: To assess the potential influence of ß-blockers (BBs) and/or angiotensin-converting enzyme inhibitors (ACEIs) on the long-term safety and outcome of VIT. METHODS: Data on the course of VIT maintenance phase, Hymenoptera re-stings, and concurrent medication were retrospectively derived from standardized questionnaires in a cohort of patients with significant cardiovascular comorbidity. RESULTS: Of 225 patients, 125 (55.6%) were taking cardiovascular medication at the time of data collection: 71 (31.6%) took an ACEI, and 40 (17.8%) took a BB. A total of 3,397 months of maintenance VIT during intake of an ACEI and 1,418 months during BB therapy were evaluated. Cumulative VIT-related reaction rates, including subjective symptoms, were 9.1% per treatment cycle and 0.31% per injection, with objective reaction rates of 1.7% and 0.06%, respectively. The incidence of adverse events was significantly higher in patients with a previous history of systemic reactions at VIT buildup (P = .004). Surprisingly, reaction rates were lower in patients taking any kind of cardiovascular medication (P = .04) or an ACEI (P = .03). The overall reexposure rate to Hymenoptera stings was 42.7%, and the field sting-induced objective reaction rate was 7.3%. There was no evidence of an increase of field sting-related relapse or hospitalization rates by concurrent cardiovascular medication. CONCLUSION: Cardiovascular medication does not impair the safety and/or the efficacy of Hymenoptera VIT.

Childhood mycosis fungoides with a CD8+ CD56+ cytotoxic immunophenotype.

Primary cutaneous T-cell lymphomas mostly occur in patients of middle and higher age. Their rarity and an oftentimes atypical clinical presentation in childhood as well as the reluctance of taking biopsies in children are reasons for a delayed diagnosis. We report the case of an 11-year-old boy with a 7-year history of slowly progressive CD8+CD56+ mycosis fungoides of the cytotoxic immunophenotype. His trunk and extremities were affected by extensive pale-erythematous patches and plaques with fine scaling. In addition, several poikilodermatous lesions were present on his thighs. Improvement was achieved by topical mometasone furoate treatment. On the basis of our observation, a brief review on cutaneous T-cell lymphomas in childhood and on CD8+ subtypes in particular is given. Clinicopathological correlation is crucial for establishing the correct diagnosis and for estimation of the prognosis.

Kerinokeratosis Papulosa of Childhood.

BACKGROUND: Kerinokeratosis papulosa (KP) is considered an extremely rare genodermatosis presenting usually as waxy papules on the trunk in childhood. OBJECTIVE: To describe and analyze the clinical, histological and potential etiopathological aspects of KP. METHODS: The dermatoscopic features of a new case of KP of childhood are investigated. The presence of human papillomavirus (HPV) DNA in lesional skin was studied by polymerase chain reaction. Furthermore, all cases of KP of childhood reported so far were reviewed. RESULTS: As a diagnostic tool, we describe for the first time a dermatoscopic feature, namely a cribriform pattern of KP, in an 11-year-old boy. In addition, we detected HPV (type 57) in his KP lesions. CONCLUSIONS: Dermatoscopic examination might be a useful tool to distinguish KP from other skin lesions, e.g. common warts. The detection of HPV type 57 might hint to an etiological role of HPV for KP.

Risk stratification of systemic allergic reactions during Hymenoptera venom immunotherapy buildup phase.

BACKGROUND: Comparability of previous studies assessing the incidence of systemic reactions during Hymenoptera venom immunotherapy (VIT) is impaired by methodical differences concerning the definition and classification of VIT-induced anaphylaxis. Our study aims to systematically evaluate the time course and clinical symptoms of VIT-related systemic reactions. PATIENTS AND METHODS: 12-year data on 818 buildup cycles including 8,504 single injections were retrieved from detailed inpatient treatment protocols. The severity of VIT-related anaphylaxis was graded according to a system proposed by the World Allergy Organization in 2010. RESULTS: Objective allergic reactions occurred in 28 (3.4 %) buildup cycles; treatment with antihistamines and/or corticosteroids was invariably effective. 23 exclusively cutaneous reactions occurred after a median time interval of 60 minutes (5-480 min.) following the last injection. 0.6 % of the buildup cycles were complicated by moderate to severe anaphylaxis, which occurred more rapidly than mere urticaria and predominantly during honeybee VIT. Patients with moderate to severe anaphylaxis more frequently reported severe index sting reactions and had higher baseline serum tryptase concentrations. CONCLUSIONS: Objective allergic reactions during VIT are rare, and severe anaphylaxis is extremely rare. The use of a consistent classification system for VIT-induced systemic reactions is required to identify risk factors not only for their general incidence, but also for the exceptionally severe anaphylactic reactions.

Angiolymphoid hyperplasia with eosinophilia and Kimura's disease - a clinical and histopathological comparison.

Angiolymphoid hyperplasia with eosinophilia (ALHE) is a benign vascular neoplasm mainly affecting middle-aged women. Lesions typically affect the head and neck region. ALHE is considered a distinct disease entity different from Kimura's disease, a benign reactive lymphoid proliferation that is predominantly seen in young Asian men although it can affect all ethnic groups. In contrast to ALHE, Kimura's disease is typically associated with peripheral blood eosinophilia, increased serum IgE and lymphadenopathy. Several case reports suggest an overlap between ALHE and Kimura's disease. We review the current literature and discuss whether AHLE and Kimura's disease might represent two extreme variants of the same disease entity.

Drug-induced exanthems: correlation of allergy testing with histologic diagnosis.

BACKGROUND: Skin biopsies are commonly performed to confirm drug-induced exanthem (DIE). However, the relevance of histologic examination in discriminating between DIE and non-DIE (NDIE) is controversial. OBJECTIVE: A retrospective analysis was performed to evaluate the reliability of histologic diagnosis of DIE. METHODS: In all, 91 patients with a skin biopsy specimen of an acute exanthem temporally related to a single identifiable drug underwent complete allergy testing. Their biopsy specimens were retrospectively re-evaluated by 2 dermatopathologists blinded to the original reports to test for discrimination between DIE versus NDIE. RESULTS: In 35 patients, non-IgE-mediated drug allergy was confirmed by allergy testing, whereas in 56 patients drug hypersensitivity could be excluded. Sensitivity of pathology reports for diagnosis of DIE reached 62.9% with a positive predictive value of 40.7%. Specificity was 41.1% with a negative predictive value of 69.7%. No significant difference in tissue eosinophilia was detected between DIE and NDIE. LIMITATIONS: This was a retrospective study. CONCLUSIONS: Dermatopathologic evaluation of skin biopsy specimens is of limited use in differentiating between DIE and NDIE. All efforts should be made to subject these patients to thorough allergy testing for definitely confirming or ruling out drug hypersensitivity.

Extrafacial indolent CD8-positive cutaneous lymphoid proliferation with unusual symmetrical presentation involving both feet.

Indolent CD8+ cutaneous lymphoid proliferation represents a recently described entity among cutaneous T-cell lymphomas that typically presents with solitary skin lesions on the face or at acral sites and usually follows an indolent clinical course. Histopathologically, this entity is characterized by a dense dermal infiltrate of non-epidermotropic, small- to medium-sized pleomorphic CD8+ T-cells of the non-activated cytotoxic phenotype showing a clear-cut grenz zone and a low proliferation index. Distinction from otherwise aggressive T-cell lymphomas bearing a cytotoxic CD8+ phenotype is fundamental. We herein present an unusual case of indolent CD8+ cutaneous lymphoid proliferation presenting in bilateral symmetrical distribution on both feet and lacking the otherwise described grenz zone. Our case widens the spectrum of possible clinical and histomorphological variations of this entity. Taking into account the distinctive and unique clinical and microscopic features of all hitherto published cases of indolent CD8+ cutaneous lymphoid proliferation we suppose that this lymphoma subtype has to be included as a new and distinct entity in the World Health Organisation (WHO)-/European Organisation for Research and Treatment of Cancer (EORTC)-classification of cutaneous lymphomas.