S2k guideline for the treatment of hidradenitis suppurativa / acne inversa - Short version

The S2k guideline on hidradenitis suppurativa/acne inversa (HS/AI) aims to provide an accepted decision aid for the selection/implementation of appropriate/sufficient therapy. HS/AI is a chronic recurrent, inflammatory, potentially mutilating skin disease of the terminal hair follicle-glandular apparatus, with painful, inflammatory lesions in the apocrine gland-rich regions of the body. Its point prevalence in Germany is 0.3%, it is diagnosed with a delay of 10.0 ± 9.6 years. Abnormal differentiation of the keratinocytes of the hair follicle-gland apparatus and accompanying inflammation form the central pathogenetic basis. Primary HS/AI lesions are inflammatory nodules, abscesses and draining tunnels. Recurrences in the last 6 months with at least 2 lesions at the predilection sites point to HS/AI with a 97% accuracy. HS/AI patients suffer from a significant reduction in quality of life. For correct treatment decisions, classification and activity assessment should be done with a validated tool, such as the International Hidradenitis Suppurativa Severity Scoring System (IHS4). HS/AI is classified into two forms according to the degree of detectable inflammation: active, inflammatory (mild, moderate, and severe according to IHS4) and predominantly inactive, non-inflammatory (Hurley grade I, II and III) HS/AI. Oral tetracyclines or 5-day intravenous therapy with clindamycin are equal to the effectiveness of clindamycin/rifampicin. Subcutaneously administered adalimumab, secukinumab and bimekizumab are approved for the therapy of HS/AI. Various surgical procedures are available for the predominantly non-inflammatory disease form. Drug/surgical combinations are considered a holistic therapy method.

Diagnostic delay in Hidradenitis suppurativa investigated using data from social media and from statutory health insurances

BACKGROUND

The chronic inflammatory skin disease hidradenitis suppurativa (HS) leads to severe pain and reduced quality of life. Nonetheless, it often takes years until a correct diagnosis is made. In this analysis, disease-related experiences and pathways of patients with HS were investigated and compared with the physicians' perspective.

METHODS

Public posts on forums and social media as well as results of a survey conducted among dermatologists and their patients on the actual medical care reality of HS in Germany were analysed. Furthermore, claims data from German health insurance companies were evaluated.

RESULTS

Patients with HS suffer from a 43.3% reduction in working ability. Dermatology (26.5%) was the most frequently consulted specialty, with HS diagnosed predominantly in the inpatient setting (43.8%). Abscesses were described as the most frequent alternative diagnosis in HS patients (53.2%). Patient-reported changes of physicians in dermatology (34.1%) and surgery (42.4%) occurred predominantly within the specialty. Dermatology received most referrals from general practitioners (67.1%), but only 12.1% from surgeons.

CONCLUSION

There is an urgent need to reduce the delay in diagnosis and the prolonged burden of disease in patients with HS. Therefore, awareness of the disease, its detection and treatment which goes beyond dermatology should be promoted, if possible as part of medical studies.

The socio-economic burden of H1-antihistamine-refractory chronic spontaneous urticaria in Germany

BACKGROUND AND STUDY AIM

Data from the AWARE study (A Worldwide Antihistamine-Refractory chronic urticaria patient Evaluation) illustrate a substantial disease burden in German patients with H1-antihistamine (-H1-AH)-refractory chronic spontaneous urticaria (CSU). Detrimental effects on patients' quality of life, poor disease control and impairment in the ability to work and perform other daily activities are reported. Based on these findings, this study aims to quantify the epidemiological and socio-economic burden of H1-AH-refractory CSU in Germany.

METHODS

To determine the epidemiological burden of H1-AH-refractory CSU, the age- and gender-specific prevalence of CSU and the proportion of H1-AH-refractory patients in Germany anonymized data from the InGef research database have been used. In a second step, the socio-economic burden in terms of lost numbers of hours in paid and unpaid work was calculated by extrapolating the age- and gender-specific work productivity and activity impairment (WPAI) observed in AWARE to the H1-AH-refractory CSU population in Germany. Finally, productivity losses in paid and unpaid work were monetized using the human capital and the friction cost approach respectively. Moreover, socio-economic burden was calculated depending on symptom control of the patients (measured by urticaria control test [UCT]).

RESULTS

In Germany, over 203,000 patients (20 years or older) had H1-AH-refractory CSU in 2018. The avoided lost paid and unpaid work hours attributable to H1-AH-refractory CSU summed up to over 100 million. Overall, the socio-economic burden of H1-AH-refractory CSU in monetary terms was evaluated at € 2.2 billion and the majority of this was due to unpaid work loss. Patients with poor disease control, as indicated by UCT score < 12, were more likely to suffer from high impairment than patients with controlled disease, resulting in a higher socio-economic burden.

CONCLUSION

The results of our analyses picture the substantial socio-economic burden of H1-AH-refractory CSU and therefore the tremendous impact it has on daily lives of individuals and society overall.

Long-term use of fumaric acid esters for the treatment of psoriasis in daily practice

BACKGROUND

Fumaric acid ester (FAE) is the most commonly prescribed first-line systemic therapy for the treatment of psoriasis in Germany. Although developed in the 1990s, only limited long-term data are available.

METHODS

Data of 200 adult psoriatic patients from 10 study centers were collected in a noninterventional, multicenter, retrospective analysis. The inclusion criteria was treatment with FAE in 2015.

RESULTS

Eighty-two percent of the patients were naive to systemic treatment. Ten percent of all patients had FAE-treatment for 10 years or longer with an average drug survival of 4.32 years. The maintenance dose was ranging from 1-4 120 mg tablets for 87.5% of the patients. In our population, 14% of the patients stopped therapy during the first six month mainly due to gastro-intestinal side effects. No serious side effects were reported. Seventy-eight percent of the patients responded to FAE therapy with improvement of their psoriasis to mild (61%) or clear (17%). The PASI 75 response was achieved in 44% of the patient during long-term treatment without remarkable differences between moderate or severe plaque psoriasis.

CONCLUSION

Our study confirms FAE therapy as a long-term, first-line treatment for moderate-to-severe plaque psoriasis.

Secondary prevention of hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a multifactorial disease with many facets of uncertain importance for optimal treatment and prevention. In order to explore options for secondary prevention in HS, we randomly and retrospectively selected 40 patients with HS that were analyzed on the basis of supposed trigger factors and proposed prevention measures. 67% of our HS patients were current smokers. They had started smoking on average 8 years prior to abscess formation. 35% complained of digestive problems and had tried different sorts of diet. We identified 2 cases of gluten-sensitive enteropathy, in which HS improved after introduction of gluten-free diet. In 7 further patients, introduction of low dairy/low carbohydrate diet considerably improved HS. 77.5% had never used any skin care in the intertriginous areas. Implementing secondary prevention by reducing irritation, avoiding shaving, improving skin care, performing laser epilation or applying fusidic acid/betamethasone cream led to an improvement in 62.5% of patients. We suggest a structured approach in daily practice in order to identify individual trigger factors. The crucial point for secondary prevention is the improvement of patient education.

[Acne inversa/hidradenitis suppurativa: An update]

Acne inversa (AI)/hidradenitis suppurativa is a chronic, recurrent, immune-mediated dermatosis characterized by deep inflammatory nodules, abscesses, fistulas, and undermined scars in skin areas bearing apocrine glands. In addition to the cutaneous manifestation, numerous AI patients show metabolic changes, spondyloarthritis, and depression. AI leads to a strong reduction in the quality of life and an impairment of the sexual life of affected individuals and often culminates in social withdrawal, stigmatization, unemployment, and suicidal thoughts. In this overview, we summarized the most important facts about AI and propose a simple algorithm for therapy.

Photodynamische Therapie – neue Wege, kritische Abwägung

In den letzten Jahren gewinnt die photodynamische Therapie (PDT) an Bedeutung in der Behandlung des chronischen Lichtschadens. Im Vordergrund steht die Behandlung der Feldkanzerisierung und damit von bösartigen, oberflächlichen epidermalen Karzinomen (aktinische Keratosen). Als Nebeneffekt wurde immer wieder ein positiver Effekt auf das Gesamterscheinungsbild und damit ein kosmetischer Effekt beschrieben. Untermauert wird dies durch Untersuchungen zur epidermalen Dicke und aktinischen Elastose nach PDT. In Kombination mit fraktionierten ablativen Lasern oder dem Mikroneedling kann eine synergistische Wirkungsverstärkung erzielt werden. Komplexe Behandlungsschemata, die PDT mit IPL, Farbstoff-Laser sowie Mikroneedling oder Mikrodermabrasion kombinieren, werden sowohl in der eigentlichen Verjüngungsbehandlung, jedoch auch zur Therapie der Akne oder auch infektiöser Hauterkrankungen eingesetzt. Die alleinige kosmetische Anwendung der PDT auf nicht sonnengeschädigter Haut steht auch aufgrund der hohen Kosten und besserer Konkurrenzmethoden nicht im Vordergrund.

Chronic spontaneous urticaria - a management pathway for patients with chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is a common and challenging disease, especially with respect to healthcare provision in the context of the German statutory health insurance system. If treatment with second-generation antihistamines is unsuccessful, current guidelines recommend further therapeutic options. However, most of these are off-label. This discrepancy between treatment according to guidelines and the ability to prescribe drugs at the expense of the statutory health insurance (reimbursability) often leads to uncertainties in everyday clinical practice. In addition, physicians prescribing certain drugs are faced with the difficulty of measuring and documenting therapeutic success/outcome. Respective outcome measurement methods have not yet been established in daily practice. Using a consensus process, a working group composed of dermatologists in private practice and specialized urticaria centers has defined a practical pathway for the implementation of current treatment recommendations based on the 2013 S3 guidelines for urticaria. Here, we present a diagnostic and therapeutic management pathway for CSU. Further, we discuss prescription issues in daily practice, including updosing of antihistamines, with regard to cost-effectiveness and drug approval on the basis of published studies and current legislation. Constituting the highest treatment level, the use of cyclosporine A, montelukast, and omalizumab, which has recently become available as therapeutic option, is reviewed. The urticaria control test (UCT) is presented as a valid outcome measure in routine practice. Our objective was to provide physicians in private practice with a practical guideline-based therapeutic decision tool, taking into account the requirements imposed by the statutory health insurance system. It is not meant to replace individualized history taking or treatment of this heterogeneous disease. Rather, we would like to suggest reference points for clinical diagnosis and treatment of CSU.

The sensitivity and specificity of optical coherence tomography for the assisted diagnosis of nonpigmented basal cell carcinoma: an observational study

BACKGROUND

The diagnostic criteria for basal cell carcinoma (BCC) using optical coherence tomography (OCT) have been described previously, but the clinical value of these findings remains unknown.

OBJECTIVES

To investigate the diagnostic value of OCT for BCC in a typical clinical setting. The primary efficacy end point was a diagnosis of BCC for each lesion. Secondary end points were the diagnosis of other possible conditions.

METHODS

This was an observational, prospective, multicentre study in which consecutive patients with nonpigmented pink lesions suspicious for BCC underwent clinical assessment, dermoscopy and OCT, with the diagnosis recorded at each stage. Once all diagnoses had been recorded, the histological results were disclosed. In total 164 patients with 256 lesions were recruited. Histology was missing for 21 lesions, leaving 235 lesions in 155 patients for analysis.

RESULTS

Sixty per cent of lesions (141 of 235) were identified as BCC by histology. A slight increase of sensitivity was noted following OCT, which did not reach statistical significance. The specificity increased significantly from 28·6% by clinical assessment to 54·3% using dermoscopy and to 75·3% with the addition of OCT (P < 0·001). The positive predictive value for the diagnosis of BCC using OCT was 85·2% [95% confidence interval (CI) 78·6-90·4], and the negative predictive value was 92·1% (95% CI 83·6-97·0). The accuracy of diagnosis for all lesions increased from 65·8% with clinical evaluation to 76·2% following additional dermoscopy and to 87·4% with the addition of OCT.

CONCLUSIONS

OCT significantly improved the diagnostic specificity for BCC compared with clinical assessment and dermoscopy alone.

Homo- and heterotypic cell-cell contacts in Merkel cells and Merkel cell carcinomas: heterogeneity and indications for cadherin switching

AIMS

Merkel cell carcinomas (MCCs) are rare but aggressive tumours associated recently with Merkel cell polyomavirus (MCV). As development and progression of several types of carcinomas can be promoted by changes in cell adhesion proteins, the aim of this study was to examine homo- and heterotypic cell contacts of Merkel cells and MCCs.

METHODS AND RESULTS

Merkel cells of healthy glabrous epidermis and 52 MCCs were analysed by double-label immunostaining, immunofluorescence and confocal microscopy. Merkel cells were connected to keratinocytes by E- and P-cadherin, desmoglein 2 and desmocollin 2. In contrast, the vast majority of MCCs (90%) contained N-cadherin, but only 67% and 65% contained E- and P-cadherin, respectively. Interestingly, P-cadherin was absent significantly more frequently in lymph node metastases than in primary tumours and by trend in more advanced clinical stages. Moreover, major subsets of MCCs synthesized desmoglein 2 and, surprisingly, tight junction proteins. No significant differences were observed upon stratification for MCV DNA, detected in 84% of tumours by real-time polymerase chain reaction.

CONCLUSIONS

Assuming that MCCs originate from Merkel cells, our data indicate a switch from E- and P-cadherin to N-cadherin during tumorigenesis. Whether the unexpected heterogeneity of junctional proteins can be exploited for prognostic and therapeutic purposes will need to be examined.

MGMT gene promoter methylation correlates with tolerance of temozolomide treatment in melanoma but not with clinical outcome

Background:

Despite limited clinical efficacy, treatment with dacarbazine or temozolomide (TMZ) remains the standard therapy for metastatic melanoma. In glioblastoma, promoter methylation of the counteracting DNA repair enzyme O⁶-methylguanine-DNA-methyltransferase (MGMT) correlates with survival of patients exposed to TMZ in combination with radiotherapy. For melanoma, data are limited and controversial.

Methods:

Biopsy samples from 122 patients with metastatic melanoma being treated with TMZ in two multicenter studies of the Dermatologic Cooperative Oncology Group were investigated for MGMT promoter methylation. We used the COBRA (combined bisulphite restriction analysis) technique to determine aberrant methylation of CpG islands in small amounts of genomic DNA isolated from paraffin-embedded tissue sections. To detect aberrant methylation, bisulphite-treated DNA was amplified by PCR, enzyme restricted, and visualised by gel electrophoresis.

Results:

Correlation with clinical data from 117 evaluable patients in a best-response evaluation indicated no statistically significant association between MGMT promoter methylation status and response. A methylated MGMT promoter was observed in 34.8% of responders and 23.4% of non-responders (P=0.29). In addition, no survival advantage for patients with a methylated MGMT promoter was detectable (P=0.79). Interestingly, we found a significant correlation between MGMT methylation and tolerance of therapy. Patients with a methylated MGMT promoter had more severe adverse events, requiring more TMZ dose reductions or discontinuations (P=0.007; OR 2.7 (95% CI: 1.32–5.7)). Analysis of MGMT promoter methylation comparing primaries and different metastases over the clinical course revealed no statistical difference (P=0.49).

Conclusions:

In advanced melanoma MGMT promoter, methylation correlates with tolerance of therapy, but not with clinical outcome.

Significance of autoimmunity to non-desmoglein targets in pemphigus

The pathogenesis of pemphigus vulgaris (PV) is a highly controversial, "hot" topic that has received considerable enrichment in recent years by both clinical and basic researchers. On the one hand, the classical view of desmogleins (Dsg) as main targets of this autoimmune disease is supported by the characterization of pathogenic anti-Dsg3 antibodies from both patients and animal models. On the other hand, fundamental doubt has been raised towards this monopathogenic view by several independent factors: (1) pemphigus lesions can be induced in Dsg3-knockout (KO) mice; (2) pemphigus sera contain multiple autoantibodies against different adhesion molecules and also cholinergic receptors; (3) experimental inhibition of PV IgG induced acantholysis can be obtained by interference with different signaling cascades regulating both calcium homeostasis and apoptosis; and (4) cholinergic agonists exhibit anti-acantholytic activity both in vitro and in vivo. The field is open for controlled clinical trials and further basic research to unfold the true story of the pemphigus enigma and provide the basis for a better treatment of pemphigus patients.

A case of cutaneous Rosai-Dorfman disease refractory to imatinib therapy

BACKGROUND

Rosai-Dorfman disease is a non-Langerhans cell histiocytosis that recently has been treated successfully with imatinib mesylate in a patient with a systemic variant of the disease.

OBSERVATIONS

We describe a 69-year-old man with cutaneous Rosai-Dorfman disease manifesting as progressive, deeply infiltrated skin lesions. Histopathologic examination of the lesions demonstrated dense dermal infiltrate positive for CD68, stabilin-1, and S-100, but not for CD1a. The histiocytes were positive for platelet-derived growth factor receptor alpha, the target molecule for imatinib. During the 5-year course of the disease, multiple therapeutic approaches (tuberculostatic drugs, topical and systemic glucocorticoids, thalidomide, isotretinoin, and methotrexate) did not result in significant improvement. Imatinib mesylate therapy (600 mg/d for 2(1/2) weeks and then 400 mg/d for 10 weeks) had no effect, despite the expression of platelet-derived growth factor receptor alpha on the histiocytes.

CONCLUSIONS

Failure of imatinib therapy in our patient may be due to a lack of functioning target molecules, the therapy protocol, or the course of the disease. Cutaneous and systemic variants of Rosai-Dorfman disease may be different clinical entities or at least may respond differently to tyrosine kinase inhibitors.

Ex vivo expanded haematopoietic progenitor cells improve dermal wound healing by paracrine mechanisms

BACKGROUND

Although dermal wounds are common, treatment remains limited and largely ineffective. Recent studies suggest that therapeutic application of progenitor cells is useful for tissue regeneration.

OBJECTIVE

We here investigated the effects exerted by the recently characterized immortalized haematopoietic progenitor cell line DKmix and their conditioned medium in a murine wound healing model.

METHODS AND RESULTS

Injection of both DKmix cells and their conditioned medium accelerated wound repair between days 3 and 10 compared with PBS-injected control mice (n = 8, P < 0.01 DKmix cells vs control, P < 0.01 conditioned medium vs control at day 6). The treated groups exhibited more CD31(+)-capillaries at day 6 after injury compared with the control group (n = 4, P < 0.01 DKmix cells vs control, P < 0.001 conditioned medium vs control), whereas there was no change in infiltrated CD68(+) macrophages. Conditioned medium of DKmix cells induced tube formation of human endothelial cells in Matrigel assays (n = 4-6, P < 0.05 conditioned medium vs control) as well as migration (n = 4, P < 0.01 conditioned medium vs control) and proliferation of murine 3T3 fibroblasts (n = 5, P < 0.05 conditioned medium vs control). Abundant levels of matrix metalloproteinase -2 and -9 in the supernatants were detected. Protein arrays of the supernatants revealed a strong secretion of cytokines and growth factors, such as monocyte chemoatractant protein-1 and GM-CSF from DKmix cells.

CONCLUSION

DKmix cells improve skin-substitute wound healing by promoting angiogenesis as well as migration and proliferation of fibroblasts. These data suggest that immortalized haematopoietic progenitor cells significantly improve dermal wound healing by paracrine effects.

Frontiers in sebaceous gland biology and pathology

The development of experimental models for the in vitro study of human sebaceous gland turned down the theory of a phylogenetic relict and led to the identification of several, unknown or disregarded functions of this organ. Such functions are the production of foetal vernix caseosa, the influence of three-dimensional organization of the skin surface lipids and the integrity of skin barrier and the influence on follicular differentiation. In addition, the sebaceous gland contributes to the transport of fat-soluble antioxidants from and to the skin surface, the natural photoprotection, the pro- and antiinflammatory skin properties and to the innate antimicrobial activity of the skin. It is mainly responsible for skin's independent endocrine function, the hormonally induced skin ageing process, the steroidogenic function of the skin as well as its thermoregulatory and repelling properties and for selective control of the hormonal and xenobiotical actions of the skin. Interestingly, sebocytes, at least in vitro, preserve characteristics of stem-like cells despite their programming for terminal differentiation. This review reports on various sebaceous gland functions, which are currently under investigation, including its role on the hypothalamus-pituitary-adrenal-like axis of the skin, the impact of acetylcholine on sebocyte biology, the activity of ectopeptidases as new targets to regulate sebocyte function, the effects of vitamin D on human sebocytes, the expression of retinoid metabolizing cytochrome P450 enzymes and the possible role of sebum as vehicle of fragrances. These multiple homeostatic functions award the sebaceous gland the role 'brain of the skin' and the most important cutaneous endocrine gland.

What causes hidradenitis suppurativa?

Hidradenitis suppurativa (HS)--a rather common, very chronic and debilitating inflammatory skin appendage disorder with a notoriously underestimated burden of disease--has long been a playground for the high priests of nomenclature: Ask a bunch of eminent dermatologists and skin pathologists to publicly share their thoughts on what causes HS, and they will soon get entrenched in a heated debate on whether this historical term is a despicable misnomer. Fortunately, the recently founded Hidradenitis Suppurativa Foundation (HSF; http://www.hs-foundation.org), to which EXP DERMATOL serves as home journal, has broken with this unproductive tradition and has encouraged publication of the current CONTROVERSIES feature. This is exclusively devoted to discussing the pathobiology of this chronic neutrophilic folliculitis of unknown origin. Although traces of terminological bickering remain visible, it does the HS experts in our virtual debate room credit that they engage in a constructive and comprehensive dissection of potential pathogenesis pathways that may culminate in the clinical picture we know under the competing terms HS or acne inversa. These experts sketch more often complementary than mutually exclusive pathogenesis scenarios, and the outlines of a conceivable consensus on the many open pathobiology questions begin to emerge in these CONTROVERSIES. Hopefully, this heralds a welcome new tradition: to get to the molecular heart of HS pathogenesis, which can only be achieved by a renaissance of solid basic HS research, as the key to developing more effective HS therapy.

Imatinib as a treatment option for systemic non-Langerhans cell histiocytoses

BACKGROUND

Systemic non-Langerhans cell histiocytoses are disorders characterized by the accumulation of histiocytes that do not meet the criteria for Langerhans cells in various organs. So far, no causative treatment is known.

OBSERVATIONS

Herein, we report the case of a 41-year-old man with Rosai-Dorfman disease, a form of systemic non-Langerhans cell histiocytoses, with histiocytic infiltrations in the skin, bone marrow, liver, and spleen. Histiocytes were positive for the imatinib target proteins platelet-derived growth factor receptor beta and KIT. The disease completely responded to treatment with 400 to 600 mg daily of imatinib for more than 7 months.

CONCLUSION

This case shows that imatinib is a powerful treatment option for patients with non-Langerhans cell histiocytoses.

Functional significance of non-neuronal acetylcholine in skin epithelia

In recent years, the physiological role of non-neuronal acetylcholine (ACh) and its receptors (AChR) in epidermal physiology has been under intense investigation. However, little is known about the role of the non-neuronal cholinergic system in inflammatory skin diseases. We chose the clinically nicotine-dependent skin disease hidradenitis suppurativa (HS) as model to study the influence of long term nicotine ingestion on epidermal morphology and AChR expression. HS is a chronic inflammatory, disabling disease of unknown pathogenesis emerging from the pilosebaceous unit of the intertriginous areas. In order to correlate our findings to specific nicotine effects, we used the organotypical coculture system (OTC) and raised artificial epidermis in the presence of nicotine. After 12 days in culture control OTC showed a mature epithelium, while nicotine treated OTCs were significantly thicker. Using immunofluorescence analysis, nicotine treated OTCs produced significantly stronger immunoreactivity (IR) for the alpha3, M(3) and M(5) AChR antisera than control. In contrast, the alpha7 nAChR antiserum showed a slightly reduced IR in the granular layer and the alpha9 nAChR IR retracted to the lower suprabasal layers. In HS epidermis we found the strongest IR for all AChR around the follicular infundibulum while in the sinus epithelia it was only weak. In contrast to the nicotine treated OTC, the alpha7 nAChR IR in the hyperplastic HS epidermis was clearly extended to all living layers. Altogether we provide first hints for a causative role of the non-neuronal cholinergic system in the pathogenesis of HS by promoting infundibular epithelial hyperplasia and thus follicular plugging.

The non-neuronal cholinergic system of human skin

In human skin both resident and transiently residing cells are part of the extra- or non-neuronal cholinergic system, creating a highly complex and interconnected cosmos in which acetylcholine (ACh) and choline are the natural ligands of nicotinic and muscarinic receptors with regulatory function in both physiology and pathophysiology. ACh is produced in keratinocytes, endothelial cells and most notably in immune competent cells invading the skin at sites of inflammation. The cholinergic system is involved in basic functions of the skin through autocrine, paracrine, and endocrine mechanisms, like keratinocyte proliferation, differentiation, adhesion and migration, epidermal barrier formation, pigment-, sweat- and sebum production, blood circulation, angiogenesis, and a variety of immune reactions. The pathophysiological consequences of this complex cholinergic "concert" are only beginning to be understood. The present review aims at providing insight into basic mechanisms of this highly complex system.

Functional Characterization of the Epidermal Cholinergic System In Vitro

The aim of this study was to analyze the influence of cholinergic and anticholinergic drugs on epidermal physiology using organotypic cocultures (OTCs). Blocking of all acetylcholine receptors (AChRs) by combined treatment with mecamylamine and atropine or treatment with strychnine (blocking alpha9nAChR) for 7-14 days resulted in a complete inhibition of epidermal differentiation and proliferation. Blockage of nicotinic (n)AChR with mecamylamine led to a less pronounced delay in epidermal differentiation and proliferation than blockage of muscarinic (m)AChR with atropine, evidenced by reduced epithelial thickness and expression of terminal differentiation markers like cytokeratin 2e or filaggrin. In OTCs treated with atropine, mecamylamine, or strychnine, we could demonstrate intracellular lipid accumulation in the lower epidermal layers, indicating a severely disturbed epidermal barrier. In addition, we observed prominent acantholysis in the basal and lower suprabasal layers in mecamylamine-, atropine-, and strychnine-treated cultures, accompanied by a decreased expression of cell adhesion proteins. This globally reduced cell adhesion led to cell death via intrinsic activation of apoptosis. In contrast, stimulation of nAChR and mAChR with cholinergic drugs resulted in a significantly thickened epithelium, accompanied by an improved epithelial maturation. In summary, we show that epidermal AChR are crucially involved in the regulation of epidermal homeostasis.

Are desmoglein autoantibodies essential for the immunopathogenesis of pemphigus vulgaris, or just ‘witnesses of disease'?

Pemphigus vulgaris (PV) is fascinating to dermatologists, epithelial biologists and immunologists alike, as its pathogenesis has been clarified to a much greater extent than that of most other organ-specific autoimmune diseases, and as it has provided abundant novel insights into desmoglein biology and pathology along the way. Historically, the most influential PV pathogenesis concept is that of Stanley and Amagai. This concept holds that autoantibodies against desmogleins are both essential and sufficient for epidermal blister formation (acantholysis) by impeding the normal functioning of these major adhesion proteins. However, as with most good theories, this landmark concept has left a number of intriguing and important questions open (or at least has not managed to answer these to everyone's satisfaction). Moreover, selected dissenting voices in the literature have increasingly called attention to what may or may not be construed as inconsistencies in this dominant PV pathogenesis paradigm of the recent past. The present debate feature therefore bravely rises to the challenge of re-examining the entire currently available evidence, as rationally and as undogmatically as possible, by provocatively asking a carefully selected congregation of experts (who have never before jointly published on this controversial topic!) to discuss how essential anti-desmoglein autoantibodies really are in the immunopathogenesis of PV. Not surprisingly, some of our expert "witnesses" in this animated debate propose diametrically opposed answers to this question. While doing so, incisive additional questions are raised that relate to the central one posed, and our attention is called to facts that may deserve more careful consideration than they have received so far. Together with the intriguing (often still very speculative) complementary or alternative pathogenesis scenarios proposed in the following pages, this offers welcome "food for thought" as well as very specific suggestions for important future research directions--within and beyond the camp of PV aficionados. The editors trust that this attempt at a rational public debate of the full evidence that is currently at hand will constructively contribute to further dissecting the exciting--and clinically very relevant!--immunopathogenesis of PV in all its complexity.

Lymphatic endothelium-specific hyaluronan receptor LYVE-1 is expressed by stabilin-1+, F4/80+, CD11b+ macrophages in malignant tumours and wound healing tissue in vivo and in bone marrow cultures in vitro: implications for the assessment of lymphangiogenesis

Lymphangiogenesis is a novel prognostic parameter for several cancers that is preferentially quantified by immunohistochemistry of the lymphatic endothelium-specific hyaluronan receptor LYVE-1. Recently, the specificity of LYVE-1 was challenged by serendipitous observations of LYVE-1 expression in rare tissue macrophages. As expression of the hyaluronan receptor-like molecule stabilin-1 is shared by sinusoidal endothelium and macrophages, a thorough analysis of LYVE-1 expression was performed using macrophage-specific markers in vivo and in vitro. In murine tumour models and excisional wound healing, LYVE-1 expression occurred in a subset of CD11b(+), F4/80(+) tissue macrophages that preferentially co-expressed stabilin-1. Upon comparison of single- and double-labelling immunofluorescence, it became apparent that LYVE-1(+) macrophages mimic sprouting and collapsed lymphatic vessels. In vitro, LYVE-1 expression was induced in 25-40% of murine bone marrow-derived macrophages upon exposure to B16F1 melanoma-conditioned medium and IL-4/dexamethasone. By FACS analysis, 11.5% of bone marrow-derived macrophages were LYVE-1(+), stabilin-1(+) double-positive, while 9.9% were LYVE-1(+), stabilin-1(-) and 33.5% were LYVE-1(-), stabilin-1(+). Northern and western analyses confirmed expression of LYVE-1 mRNA and protein in bone marrow-derived macrophages. In the light of the current debate about true endothelial trans-differentiation versus endothelial mimicry of monocytes/macrophages, LYVE-1(+), stabilin-1(+) non-continuous endothelial-like macrophages will require further developmental and functional analyses. In conclusion, the findings imply that LYVE-1 staining must be supplemented by double labelling with macrophage markers in order to differentiate clearly between LYVE-1(+) lymphatics and LYVE-1(+) tumour-infiltrating macrophages. This improved approach will help to clarify the prognostic significance of lymphangiogenesis in malignant tumours.

Decline in angiogenic factors, such as interleukin-8, indicates response to chemotherapy of metastatic melanoma

Serum concentrations of angiogenic factors have been reported to correlate with tumour burden and prognosis in metastatic melanoma. The present study was performed to assess the value of angiogenic factors in serum in indicating response or failure to chemotherapy and immunochemotherapy in stage IV melanoma. Thirty-five patients suffering from stage IV melanoma according to the American Joint Committee on Cancer (AJCC) criteria were included in this prospective study. Before and following chemotherapy or immunochemotherapy, serum levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF-AB), vascular cell adhesion molecule-1 (VCAM-1) and interleukin-8 (IL-8) were measured. Staging examinations following chemotherapy revealed 15 patients with response to therapy (complete response, partial response, stable disease), 14 patients with progressive disease and six patients with mixed response. Patients who responded to therapy showed a significant decrease in the serum level of IL-8 at the time of staging examinations, whereas patients with progressive disease did not. Following chemotherapy, serum concentrations of PDGF-AB had significantly decreased in both patients with response and patients with progressive disease. Comparing the VEGF and bFGF levels of responders and non-responders after a single administration of cytostatics showed significantly lower concentrations in patients with response to therapy. In all patients, a high intra- and inter-individual variability of serum values was observed during application of therapy. It can be concluded that low IL-8 serum levels after chemotherapy indicate response to chemotherapy in stage IV melanoma patients. The persistence of elevated serum levels of VEGF and bFGF following the initial cytostatic administration may help to identify patients resistant to chemotherapy. The distinct variability of serum levels indicates that processes other than tumour angiogenesis also influence the serum concentration of the examined angiogenic factors.

The chemoresistance gene ABCG2 (MXR/BCRP1/ABCP1) is not expressed in melanomas but in single neuroendocrine carcinomas of the skin

BACKGROUND

As the molecular mechanisms in melanoma chemoresistance remain unknown to date, we hypothesized these tumors to express the ATP-binding cassette (ABC) transporter G2 (ABCG2/MXR/BCRP1/ABCP1), a recently detected membrane transporter and putative stem-cell marker. Besides melanoma, we addressed the neuroendocrine carcinoma of the skin (Merkel cell carcinoma), another cutaneous cancer supposed to originate from neuroectoderm and usually chemoresistant.

METHODS AND RESULTS

Upon semiquantitative reverse transcription polymerase chain reaction, ABCG2 mRNA expression was not upregulated in 18 melanoma resection specimens when compared with 19 acquired melanocytic nevi from which melanomas are known to often arise (Mantel-Haenszel test, p=0.3). At protein level, immunohistochemistry was negative in all 66 investigated melanoma resection specimens (50 primary melanomas and 16 cutaneous/subcutaneous metastases) and in 19 acquired melanocytic nevi. Among 29 neuroendocrine carcinomas of the skin, ABCG2 protein was detected in single clusters of cells in three tumors. As a positive control, three dermatofibrosarcomas were also stained and showed ABCG2 protein expression of the endothelial cells of the blood vessels.

CONCLUSION

Altogether, chemoresistance of melanomas and neuroendocrine carcinomas of the skin cannot be explained by expression of the ABCG2-chemoresistance gene. Most of these tumors do not exhibit this potential stem-cell feature.