Novel functions of S1P in chronic itchy and inflammatory skin diseases.

S1P is a pleotropic sphingolipid signalling molecule that acts through binding to five high-affinity G-protein coupled receptors. S1P-signaling affects cell fate in a multitude of ways, e.g. influencing cell differentiation, proliferation, and apoptosis, as well as playing an important role in immune cell trafficking. Though many effects of S1P-signaling in the human body have been discovered, the full range of functions is yet to be understood. For inflammatory skin diseases such as atopic dermatitis and psoriasis, evidence is emerging that dysfunction and imbalance of the S1P-axis is a contributing factor. Multiple studies investigating the efficacy of S1PR modulators in alleviating the severity and symptoms of skin conditions in various animal models and human clinical trials have shown promising results and validated the interest in the S1P-axis as a potential therapeutic target. Even though the involvement of S1P-signalling in inflammatory skin diseases still requires further clarification, the implications of the recent findings may prompt expansion of research to additional skin conditions and more S1P-axis modulatory pharmaceuticals.

[Alpha-gal syndrome : Overview of clinical presentation and pathophysiology]. / Alpha-Gal-Syndrom : Ein Überblick zum klinischen Bild und zu pathophysiologischen Konzepten.

In the world of allergology, alpha-gal syndrome remains one of the most fascinating discoveries over the last 15 years as it is triggered by specific IgE directed against the immunogenic sugar galactose-α­1,3­galactose (alpha-gal), found foremost in mammalian meat, milk and products derived thereof, potentially resulting in anaphylaxis. Also, mammalian-derived drugs and medical products have been identified as possible culprits. Nonetheless, tick bites remain the major cause of specific alpha-gal-sIgE. Herein, we summarize the current clinical knowledge and pathophysiology of alpha-gal syndrome in order to better understand this disease.

IgE autoantibodies in serum and skin of non-bullous and bullous pemphigoid patients.

BACKGROUND: Non-bullous pemphigoid (NBP) is a pemphigoid variant which frequently resembles other pruritic skin diseases. In contrast with bullous pemphigoid (BP), blisters are absent. In BP, previous studies showed that IgE autoantibodies may be involved in its pathogenesis. IgE-activated mast cells, basophils and eosinophils may participate in BP by inducing pruritus and possibly blister formation, although the differential role of IgE in NBP compared with BP has not yet been described. OBJECTIVE: To assess IgE in serum and skin of NBP and BP patients. METHODS: We examined total IgE and pemphigoid-specific IgE in the serum of 68 NBP and 50 BP patients by enzyme-linked immunosorbent assay (ELISA). Sera of 25 pemphigus patients and 25 elderly patients with pruritus were included as controls. Skin biopsies of 14 NBP and 14 BP patients with the highest IgE titres to NC16A were stained for IgE by immunofluorescence techniques. RESULTS: Total IgE was elevated in 63% of NBP and 60% of BP patients, and in 20% of pemphigus controls, as well as 60% of elderly controls. IgE ELISAs were more frequently positive in BP than in NBP (NC16A 18% vs. 9%, P = 0.139; BP230 34% vs. 22%, P = 0.149). IgE ELISAs for NC16A and BP230 were positive in 8% and 20% of elderly controls, respectively, while all pemphigus controls were negative. Two of 28 biopsies (7%; one NBP, one BP) showed linear IgE along the basement membrane zone, while in most biopsies (71% NBP; 86% BP) IgE was bound to dermal cells. CONCLUSION: Since IgE was present in the serum and skin of both NBP and BP patients, this supports IgE-dependent mechanisms common to both diseases, such as pruritus. However, it remains to be elucidated whether IgE contributes to blister formation in BP.

Neurological disorders are associated with bullous pemphigoid.

BACKGROUND: Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease with an increased incidence particularly among the elderly. Several studies have recently reported an association between BP and neurological disorders. OBJECTIVE: To evaluate the association between BP and neurological disorders in a single centre in Germany. METHODS: We retrospectively assessed 183 patients with BP (diagnosed between 2011 and 2015) and 348 age- and sex-matched controls for neurological disorders. The latter were confirmed either by a neurologist or psychiatrist. RESULTS: Overall, there was a highly statistically significant association between BP and neurological disorders (P < 0.0001). These included dementia (P < 0.0001), Parkinson`s disease (P = 0.0434), stroke (P = 0.0015) and other neurological disorders but not Alzheimer's diseases, which was more common among patients in the control group. CONCLUSION: Our cohort of bullous pemphigoid and neurological disorders demonstrates a significant association between bullous pemphigoid and neurological disorders, including dementia, Parkinson's disease and stroke. These observations support the need for future studies in order to elucidate the immunological mechanisms responsible for these comorbidities.

[Neurophysiology of atopic pruritus]. / Neurophysiologie des atopischen Pruritus.

Pruritus is one of the major symptoms of inflammatory skin diseases and strongly affects the quality of life in patients. Although the perception of pruritus and pain are closely intertwined, pruritus represents a distinct sensation, which is also significantly different to pain at a neurophysiological level. The pathophysiological basis of chronic and acute pruritus is not fully understood. Besides histamine, a plethora of different neuromediators of itch, including neurotrophins, neuropeptides and their corresponding receptors, have been identified. In atopic dermatitis the release of these mediators leads to an activation of immune cells, such as mast cells and eosinophilic granulocytes, which in turn release neuromediators and cytokines that activate peripheral neurons. This review focuses on the neurophysiological interactions which regulate pruritus and summarizes the function of neurological and inflammatory mediators in atopic pruritus.

Human basophils are a source of - and are differentially activated by - IL-31.

BACKGROUND: Basophils are important effector cells involved in the pathogenesis of inflammatory skin diseases including chronic urticaria which is associated by increased IL-31 serum levels. So far the effects of IL-31 on human basophils are unknown. OBJECTIVE: To analyse the functional role of IL-31 in basophil biology. METHODS: IL-31 expression was evaluated in skin samples derived from chronic spontaneous urticaria patients. Oncostatin M receptor (OSMR), IL-31 receptor A (RA) and IL-31 protein expressions were analysed on human basophils from healthy donors. Basophil responses to IL-31 were assessed for chemotaxis, externalization of CD63 and CD203c as well as the release of histamine, IL-4 and IL-13. RESULTS: IL-31RA and OSMR were expressed on human basophils. IL-31 was strongly expressed in the skin of patients with chronic spontaneous urticaria and was released from isolated basophils following either anti-IgE, IL-3 or fMLP stimulation. IL-31 induced chemotaxis and the release of IL-4 and IL-13 which was specifically inhibited by anti-IL-31RA and anti-OSMR. Conversely, IL-31 had no effect on CD63 and CD203c externalization or histamine release. CONCLUSIONS AND CLINICAL RELEVANCE: Human basophils are a source of -and are activated by - IL-31 with the release of pro-inflammatory cytokines and the induction of chemotaxis indicating an important novel function of IL-31 in basophil biology.

H1-antihistamine-refractory chronic spontaneous urticaria: it's worse than we thought - first results of the multicenter real-life AWARE study.

BACKGROUND: Most data on chronic spontaneous urticaria (CSU) originate from highly selected patient populations treated at specialized centres. Little is known about CSU patient characteristics and the burden of CSU in routine clinical practice. AWARE (A World-wide Antihistamine-Refractory chronic urticaria patient Evaluation) is an ongoing global study designed to assess chronic urticaria in the real-life setting. OBJECTIVE: To describe the baseline characteristics of the first 1539 German AWARE patients with H1-antihistamine-refractory CSU. METHODS: This prospective non-interventional study included patients (18-75 years) with a diagnosis of H1-antihistamine-refractory CSU for > 2 months. Baseline demographic and disease characteristics, comorbidities, and pharmacological treatments were recorded. Quality of life (QoL) was assessed using the dermatology life quality index (DLQI), chronic urticaria QoL questionnaire (CU-Q2 oL), and angioedema QoL questionnaire (AE-QoL, in cases of angioedema). Previous healthcare resource utilization and sick leave data were collected retrospectively. RESULTS: Between March and December 2014, 1539 patients were assessed in 256 sites across Germany. The percentage of females, mean age, and mean body mass index were 70%, 46.3 years, and 27 kg/m2 , respectively. The mean urticaria control test score was 7.9, one in two patients had angioedema, and the most frequent comorbidities were chronic inducible urticaria (CIndU; 24%), allergic rhinitis (18.2%), hypertension (18.1%), asthma (12%), and depression (9.5%). Overall, 57.6% of patients were receiving at least one pharmacological treatment including second-generation H1-antihistamines (46.3%), first-generation H1-antihistamines (9.1%), and corticosteroids (15.8%). The mean DLQI, total CU-Q2 oL, and total AE-QoL scores were 8.3, 36.2, and 46.8, respectively. CSU patients reported frequent use of healthcare resources, including emergency services (29.7%), general practitioners (71.9%), and additional allergists or dermatologists (50.7%). CONCLUSIONS AND CLINICAL RELEVANCE: This study reveals that German H1-antihistamine-refractory CSU patients have high rates of uncontrolled disease, angioedema, and comorbid CIndU, are undertreated, have impaired QoL, and rely heavily on healthcare resources.

Regulation of melanocortin 1 receptor in allergic rhinitis in vitro and in vivo.

BACKGROUND: α-melanocyte-stimulating hormone (α-MSH) was shown to inhibit allergic airway inflammation and exert suppressive effects on human basophils. OBJECTIVE: This study aims to extend our current knowledge on the melanocortin 1 receptor (MC1R) expression in nasal tissue of patients with allergic rhinitis (AR) and functional effects of α-MSH in human basophils especially from patients with allergic rhinitis. METHODS: MC1R expression before and after nasal allergen provocation was studied in nasal mucosal tissue of AR patients and in a mouse model of allergic airway inflammation using immunofluorescence. In vitro regulation of the MC1R and CD203c surface expression on whole-blood basophils of patients with AR and controls was assessed with flow cytometry. Functional effects of α-MSH on isolated basophils were analysed regarding apoptosis with flow cytometry and chemotaxis using a Boyden chamber assay. RESULTS: We detected an accumulation of MC1R-positive basophils in nasal mucosa tissue of patients with AR 24 h after nasal allergen provocation. Such accumulation was not present in mucosa sections from healthy controls. In mice with allergic airway inflammation, we found a clear accumulation of MC1R-positive basophils in the nasal tissue compared to control mice. MC1R expression was inducible in AR patients and controls by stimulation with anti-IgE. α-MSH inhibited anti-IgE and grass pollen induced upregulation of CD203c, but had no effect on chemotaxis or apoptosis of basophils in vitro. CONCLUSIONS AND CLINICAL RELEVANCE: MC1R-positive basophils accumulate in the nasal mucosa of patients with AR after nasal allergen provocation. Since α-MSH suppresses proinflammatory effector functions in human basophils via the MC1R, it constitutes an interesting novel target for modulating the allergic inflammatory response.

Human basophil chemotaxis and activation are regulated via the histamine H4 receptor.

BACKGROUND: IgE-mediated cross-linking of FcεRI results in the release of mediators stored in basophil granules, such as histamine and proteases, and in the de novo synthesis of sulfidoleukotrienes. OBJECTIVE: In this study, we investigated the role of the histamine receptors, in particular that of the histamine H4 receptor (H4R), in modulating human basophil function. METHODS: The mRNA expression of the histamine receptors was measured by real-time PCR. Migration of basophils was assessed using the modified Boyden chamber technique. The expression levels of CD63 and CD203c on the cell surface and the sulfidoleukotriene release were determined by flow cytometry and ELISA, respectively. RESULTS: We could show that highly purified basophils express the H1R, H2R, and H4R but not the H3R mRNA. Human basophils expressed higher H4R mRNA levels as compared to the expression levels of the H1R (P < 0.01). Histamine and the H4R agonist ST-1006 initiated active migration of basophils (P < 0.001). A significant reduction in FcεRI cross-linking-mediated surface expression of CD63 and CD203c was observed on basophils after pre-incubation with histamine or the specific H4R agonist ST-1006 (P < 0.01). The synthesis and release of sulfidoleukotrienes from basophils after activation with different stimuli, by FcεRI cross-linking or by stimulation with hymenoptera venom allergens, were significantly reduced by histamine or the H4R agonist ST-1006 (P < 0.05-0.001). CONCLUSION: These data imply that the H4R regulates IgE-dependent processes in human basophils and provides a novel function of the H4R preventing an overwhelming immune reaction by engagement of a negative feedback loop.

Childhood atopic dermatitis-Brain-derived neurotrophic factor correlates with serum eosinophil cationic protein and disease severity.

Several studies have shown that neurotrophins including brain-derived neurotrophic factor (BDNF) play a role in chronic inflammatory skin diseases such as atopic dermatitis (AD). BDNF is increased in the serum samples of adults with AD. Interestingly, eosinophils of these patients can release and produce BDNF. We analyzed BDNF serum levels with ELISA and their correlation with SCORAD score, eosinophil cationic protein (ECP), total IgE, IL-4, IL-13 and IL-31 in children with AD (n = 56) compared to nonatopic healthy children (n = 25). In addition, we analyzed FLG loss-of-function mutations in 17 children with AD and their connection to BDNF. BDNF serum levels were significantly higher in children with AD. Further, BDNF correlated with disease activity, serum ECP, and total IgE serum levels in AD. There was no difference in BDNF levels of filaggrin-positive or filaggrin-negative children with AD, and there was no correlation of BDNF with IL-31 and Th2 cytokines including IL-4 and IL-13. Together, our data add new insights into the pathophysiology of AD, suggesting that serum BDNF which correlates with disease severity contributes to the regulation of inflammation in an eosinophil-, but not Th2-dependent manner.

Pirfenidone-induced severe phototoxic reaction in a patient with idiopathic lung fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal pulmonary disease with an estimated 5-year survival of approximately 20%. Pirfenidone is a novel orally available antifibrotic agent that reduces disease progression and improves survival of patients with IPF. The most common adverse effects of pirfenidone include gastrointestinal symptoms, hepatic dysfunction or skin photosensitivity and rash. A 64-year-old male patient presented in our clinic with a strong generalized exfoliative erythema and intense itching accompanied by fatigue and mild fever after a mild sun exposure for 5 days during holidays in Turkey. The patient had been diagnosed with IPF 2 months ago and 1 month later he started a therapy with pirfenidone with good tolerability. OBJECTIVE: In this report, we noted a severe phototoxic reaction under treatment with pirfenidone which underlies the potential phototoxic effect of this drug besides the already reported photosensitivity. METHODS: Routine laboratory tests and a skin biopsy were performed. RESULTS: Laboratory tests indicated increased markers of inflammation. The skin biopsy showed a perivascular lymphocytic inflammatory infiltrate, ballooning of keratinocytes with increased apoptosis. These findings were most consistent with a severe phototoxic reaction to pirfenidone which had been directly discontinued. The patient was started on oral methylprednisolone 100 mg/day which was gradually tapered off along with topical corticosteroids (mometasone furoate 0.1% cream) and oral antihistamines. This treatment led to a slow but complete resolution of the skin lesions within 20 days. CONCLUSION: To our knowledge, this is the first reported case of a severe phototoxic reaction during treatment with pirfenidone. Our aim by presenting this case is to increase the awareness of clinicians for severe phototoxic effects of oral pirfenidone.

European EADV network on assessment of severity and burden of Pruritus (PruNet): first meeting on outcome tools.

BACKGROUND: Chronic pruritus is a frequently occurring symptom of various dermatoses that causes a high burden and impaired quality of life. An effective anti pruritic therapy is important for the patient, but its effectiveness is difficult to evaluate. Diverse methods and interpretations of pruritic metrics are utilized in clinical trials and the daily clinical practice in different countries, resulting in difficulties comparing collected data. METHODS: We founded a European Network on Assessment of Severity and Burden of Pruritus (PruNet) that is supported by the EADV. PruNet consists of 28 experts from 15 EU countries (21 dermatologists, 5 medical informaticists, 2 psychologists) and aims to unify the assessment of itch in routine dermatological care. Following a preliminary survey, a consensus conference was held in order to agree upon the prioritization of patient-reported outcome tools. RESULTS: Through utilizing the Delphi method, it was agreed that tools for measuring itch intensity (ex. the visual analogue scale) and quality of life (ex. ItchyQoL) are of primary importance and should urgently be foremost validated. CONCLUSION: The validation and harmonization of standards are needed for the improvement of quality care for patients suffering from pruritic dermatoses. This summer, the first validation studies in several EADV member countries already began.

[Update on the cutaneous neurobiology of pruritus]. / Aktuelles zur kutanen Neurobiologie von Pruritus.

The pathogenesis of chronic and acute pruritus is not yet completely understood. Interactions of neurons with resident and nonresident skin cells seem to play an important role in the regulation of pruritus. Neuronal cells which express specific receptors and are capable of releasing neuromediators play an active role in this interaction. Furthermore, released neuromediators can activate immune cells including mast cells and eosinophils, which are increased in the inflammatory infiltrate of many pruritic skin diseases. Mast cells and eosinophils express receptors for neuromediators themselves. In addition, they can release neurotrophins including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and cytokines including interleukin (IL)-31 which correlate with disease activity in patients with inflammatory skin diseases including atopic dermatitis and induce neuronal outgrowth. In part, a correlation of these mediators has also been described with pruritus. Although the interplay between transient and resident cells in the skin with peripheral nerves, mast cells, and eosinophils plays an important role in the mutual activation, the neurobiological mechanisms that lead to pruritus are not completely clear yet.

Activation of KIT modulates the function of tumor necrosis factor-related apoptosis-inducing ligand receptor (TRAIL-R) in mast cells.

BACKGROUND: Mastocytosis is characterized by the accumulation of mast cells (MCs) associated with activating mutations of KIT. Tumor necrosis factor-related apoptosis-inducing ligand receptors (TRAIL-Rs) are preferentially expressed on neoplastic cells and induce the extrinsic apoptotic pathway. Recent studies reported on the expression of TRAIL-Rs and TRAIL-induced apoptosis in cultured human MCs, which depend on stem cell factor (SCF)-induced or constitutive KIT activation. MATERIAL AND METHODS: We sought to further define the impact of TRAIL-Rs on MCs in vivo and in vitro. Using Cre/loxP recombination, we generated mice with MC-specific and ubiquitous knockout of TRAIL-R. In these mice, anaphylaxis and numbers of MCs were investigated. We also explored the expression and function of TRAIL-Rs in cultured murine and human MCs upon activation of KIT. By conducting immunofluorescence staining, we analyzed the expression of TRAIL-Rs in MCs infiltrating the bone marrow of patients with mastocytosis. RESULTS: MC-specific deletion of TRAIL-R was associated with a slight, but significant increase in anaphylaxis. Numbers of MCs in MC-specific knockouts of TRAIL-R were comparable to controls. Whereas cultured IL-3-dependent murine MCs from wild-type mice were resistant to TRAIL-induced apoptosis, SCF-stimulated MCs underwent apoptosis in response to TRAIL. Interestingly, activating KIT mutations also promoted sensitivity to TRAIL-mediated apoptosis in human MCs. In line with these findings, MCs infiltrating the bone marrow of patients with mastocytosis expressed TRAIL-R1. CONCLUSIONS: Activation of KIT regulates the function of TRAIL-Rs in MCs. TRAIL-R1 may represent an attractive diagnostic and therapeutic target in diseases associated with KIT mutations, such as mastocytosis.

[Pathogenesis of prurigo nodularis]. / Pathogenese der Prurigo nodularis.

BACKGROUND: Prurigo nodularis is a chronic reaction pattern associated with severe pruritus that markedly affects the quality of life in patients. PATHOGENESIS: The pathogenesis of prurigo nodularis is not completely clear. Patients have an increased number of substance P and calcitonin gene-related peptide positive nerves in the dermis. Eosinophils and mast cells are in close vicinity to peripheral nerves and increased in numbers in the inflammatory infiltrate in prurigo nodularis. Nerve growth factor (NGF) is increased in lesional skin of patients and can be released by mast cells and eosinophils. In addition, NGF modulates the functional activity of mast cells and eosinophils. Recently, higher levels of the novel pruritic cytokine IL-31 were found in the skin of patients with prurigo nodularis than other pruritic skin diseases. CONCLUSION: The pathogenesis of prurigo nodularis seems to be regulated by immunological and neuronal plasticity which will be highlighted in the current article.

[Prurigo nodularis: its association with dermatoses and systemic disorders]. / Prurigo nodularis bei Dermatosen und systemischen Erkrankungen.

BACKGROUND: Prurigo is seen in various dermatological diseases, but also in systemic and neurological diseases. OBJECTIVES: Which diseases in dermatology, internal medicine and neurology are linked to prurigo nodularis? MATERIAL AND METHODS: We describe the various entities that are associated with prurigo and discuss pathogenetic and therapeutic implications. RESULTS: In dermatology prurigo nodularis is most frequently seen in atopic dermatitis, but also in cutaneous lymphomas, mycobacterial skin infections and bullous diseases. Among systemic diseases, prurigo nodularis frequently is associated with pruritus of chronic renal or hepatic diseases. Prurigo nodularis is also seen in hematological and metabolic diseases (such as solid tumors, lymphoma, diabetes mellitus). The pathophysiology of prurigo is only partly understood. Treatment of prurigo nodularis is often challenging and a multimodal approach is advisable. CONCLUSION: Prurigo nodularis is a skin manifestation of chronic pruritus caused by various diseases in dermatology, internal medicine and neurology. An interdisciplinary approach should be taken for diagnosis and therapy.

EAACI taskforce position paper: evidence for autoimmune urticaria and proposal for defining diagnostic criteria.

An autoimmune subset of chronic spontaneous urticaria is increasingly being recognized internationally, based on laboratory and clinical evidence that has accrued over the last 20 years. This evidence has been reviewed by a taskforce of the Dermatology section of the European Academy of Allergy and Clinical Immunology. Functional autoantibodies in chronic urticaria (CU) patient sera have been demonstrated against IgE and FcεRIα by basophil and mast cell histamine release assays and by basophil activation assays. Antibody specificity has been confirmed by immunoassay, but there is a poor correlation between functionality and immunoreactivity. Approximately 25% of CU patients have a positive basophil histamine release assay and show autoreactivity (a positive autologous serum skin test), whereas 50% are negative regarding both. Functionality of CU sera appears to be complement dependent on mast cells but not exclusively on basophils. Basophil activation by CU sera is predominantly restricted to IgG1 and IgG3 subclasses. Circumstantial evidence for CU being an autoimmune disease comes from an observed association with other autoimmune diseases, a strong association between serum functionality and HLA-DR4 haplotype and the good response of CU patients to immunotherapies. It was proposed that a study should be undertaken to prospectively validate potentially relevant clinical criteria (from the history, examination and routinely available clinical investigations) against a new 'gold standard' for the diagnosis of ACU (positive autoreactivity, functional bioassay and immunoassay) to define preliminary criteria sets for the diagnosis of ACU based on clinical and laboratory features with highest individual sensitivity and specificity.

[Unclear pruritic and urticarial skin inflammation. Bed bug attack]. / Juckreiz und urtikarielle Entzündungsreaktion der Haut unklarer Genese. Cimicosis durch die Bettwanze.

A 27-year-old woman presented with severe pruritus for a few weeks and diffuse urticarial erythema with pinhead-sized papules over the entire body. The skin lesions occurred directly after a stay in her secondary residence in London. The medical history, clinical picture and histological feature of an arthropod reaction in the skin biopsy, coupled with patient offering a bed bug specimen as evidence, secured the diagnosis of a cimicosis.