Mast cell‐deficient mice Mcpt5Cre/Dicer fl/fl redefine the role of mast cells in experimental bullous pemphigoid

Background

Bullous pemphigoid (BP) is the most frequent autoimmune blistering disease of the skin affecting the elderly. BP is immunopathologically characterized by autoantibodies against BP180 and BP230. With the growing evidence of cell‐mediated autoimmunity in the pathogenesis of BP, it still remains unclear whether mast cells (MCs) are involved, due to conflicting data obtained from Kit‐dependent MC‐deficient mouse models.

Objectives

To clarify the role of MCs in experimental BP; the dynamics in cutaneous MC numbers, associated immune cells and the development of disease in Kit‐independent MC‐deficient mouse model.

Methods

Employing a recently established murine adult passive transfer model of BP induced by the transfer of pathogenic immunoglobulin G (IgG), lesional skin biopsies were investigated histologically and immunohistochemically for the time‐dependent MC accumulation and dermal infiltration.

Results

The numbers of cutaneous MCs increased following the induction of BP, in part, maintained by MC proliferation. Numbers of T cells, neutrophils and eosinophils in the skin also increased after BP induction, with eosinophils showing a preferential co‐localization with MCs. Furthermore, clinical disease manifestation in MC‐deficient Mcpt5Cre/Dicer^fl/fl mice remained unchanged compared to MC‐sufficient Dicer^fl/fl mice. The composition of the immune cell infiltration including as T cells, neutrophils and eosinophils was largely unaffected by the absence of MCs.

Conclusion

MCs do not play a pivotal role in the pathogenesis of passive IgG‐transfer mediated BP model. Their increase in number may be a bystander effect following tissue injury. We therefore suggest caution regarding the selection of MCs as sole targets for the development of novel drugs for BP.

Coexistence of bullous pemphigoid with neuropsychiatric comorbidities is associated with anti-BP230 seropositivity

BACKGROUND

While clustering of bullous pemphigoid (BP) with neuropsychiatric diseases is well-established, the clinical and immunological profile of BP patients with this comorbidity remains to be decisively determined.

OBJECTIVES

To evaluate the burden of neurological and psychiatric comorbidities among patients with BP and to elucidate the clinical, immunological and immunopathological features of patients with BP and comorbid neuropsychiatric conditions.

METHODS

We performed a retrospective study encompassing patients diagnosed with BP throughout the years 2009-2020 in a specialized tertiary referral centre. Multivariate logistic regression model was used to identify predictors of neuropsychiatric conditions among patients with BP.

RESULTS

The study included 273 patients with BP, of whom 123 (45.1%) presented with comorbid neuropsychiatric disease. Compared to the remaining patients with BP (n = 150), those with pre-existing neuropsychiatric diseases demonstrated older mean [standard deviation (SD)] age [81.7 (9.1) vs. 76.9 (10.1); P < 0.001], female preponderance (65.0% vs. 49.3%; P = 0.009), higher seropositivity rate of anti-BP230 (67.7% vs. 36.5%; P = 0.006) and higher levels of anti-BP180 NC16A IgG [651.3 (1279.6) vs. 370.4 (818.6) U/mL; P = 0.039]. In multivariate analysis, anti-BP230 seropositivity was independently associated with coexistence of BP with neuropsychiatric conditions [adjusted odds ratio (OR), 3.43; 95% CI, 1.24-9.52; P = 0.018]. In a sensitivity analysis confined to patients with neurological diseases (n = 103), older age [82.1 (8.4) vs. 77.2 (10.3); P < 0.001] and increased anti-BP230 seropositivity (68.0% vs. 39.7%; P = 0.018) were identified.

CONCLUSIONS

The coexistence of BP with neuropsychiatric diseases is independently associated with the generation of anti-BP230 antibodies.

Incidence of pemphigoid diseases in Northern Germany in 2016 - first data from the Schleswig-Holstein Registry of Autoimmune Bullous Diseases

BACKGROUND

Autoimmune bullous diseases (AIBD) are rare disorders characterized by autoantibody formation against components of adhesion molecules; in pemphigoid diseases (PD), these are proteins of hemidesmosomes and basement membrane, important for cell-matrix adhesion in skin and/or mucous membranes. Incidences of these diseases vary considerably between different populations.

OBJECTIVES

To establish a registry prospectively recruiting all AIBD patients in a geographically well-defined region in Northern Germany (Schleswig-Holstein).

METHODS

Only patients with verified disease (by clinical presentation, histology, direct and/or indirect immunofluorescence and /or ELISA) living in Schleswig-Holstein were included. Incidences of PD were estimated based on the total number of inhabitants in Schleswig-Holstein, stratified by birth year and sex.

RESULTS

Of 67 patients with PD [35 male, 32 female, mean age 75 (standard deviation 14.3 years)], 83% were patients with bullous pemphigoid [n = 56, 28 male, 28 female, mean age 78 (SD 9.9)]. The resulting crude incidences were 23.4 patients/million/year for all pemphigoid patients, 19.6 patients/million/year for bullous pemphigoid (age-standardized 16.9 patients/million/year) with a strong increase in bullous pemphigoid patients in the age group of 85-90 years with 262 patients/million/year. Incidences for bullous pemphigoid were higher in urban compared to rural areas. Other PD (mucous membrane pemphigoid, linear IgA disease, anti-p200 pemphigoid) were less frequent with crude incidences of 2.1, 1.0 and 0.7 patients/million/year, respectively.

CONCLUSIONS

This study prospectively analyses the incidence of PD in a carefully defined geographical area. The highest incidence among PD patients was found for bullous pemphigoid. The incidence of bullous pemphigoid is considerably increased compared to previous reports and reveals regional differences. Further studies are needed in order to clarify these findings.

Diagnostik und Therapie des Anti-p200-Pemphigoids

Pemphigoid-Erkrankungen sind eine Gruppe von 7 Autoimmunerkrankungen, bei denen es durch Bildung von Autoantikörpern gegen Proteine des dermal-epidermalen Adhäsionskomplexes zu einer Entzündung der Haut und Schleimhäute kommt, die zur Bildung von Blasen und Erosionen führen können. Die einzelnen Pemphigoid-Erkrankungen weisen in ihrem klinischen Bild Ähnlichkeiten, teilweise aber auch erhebliche Unterschiede auf. Die genaue Differenzierung der einzelnen Pemphigoid-Erkrankungen ist oft nur durch eine gründliche immunpathologische Diagnostik möglich. Dies betrifft insbesondere die Differenzierung zwischen bullösem Pemphigoid, Epidermolysis bullosa acquisita und Anti-p200-Pemphigoid. Letztere ist die zuletzt definierte Pemphigoid-Erkrankung und die einzige mit immer noch unbekanntem Autoantigen. In dem vorliegenden Artikel präsentieren wir den typischen Verlauf eines Anti-p200-Pemphigoids und gehen detailliert auf die immunpathologische Diagnostik ein, die benötigt wird, um das Anti-p200-Pemphigoid von anderen Pemphigoid-Erkrankungen zu unterscheiden.

Klinik für Dermatologie, Allergologie und Venerologie der Universität zu Lübeck: Interaktion von Forschung und klinischer Versorgung

Die Ursprünge der Lübecker Universitäts-Hautklinik reichen in die 30er-Jahre des letzten Jahrhunderts zurück. Die Klinik hat in den letzten Jahrzehnten eine konsequente bauliche und inhaltliche Weiterentwicklung erfahren und verfügt heute über 85 Betten auf 2 Stationen und in einer Tagesklinik. Ein modernes Weiterbildungsprogramm, das auf einem Rotationsprinzip durch 5 verschiedene stationäre und ambulante Teams beruht, vermittelt alle wesentlichen Lerninhalte der Dermatologie. Die Erweiterung der Klinik in den letzten Jahren beruhte auf einer engen Interaktion von Grundlagenforschung und klinischer Tätigkeit, insbesondere auf dem Gebiet kutaner Autoimmunerkrankungen und entzündlicher Dermatosen. Die wissenschaftliche Entwicklung der Hautklinik profitierte seit 2007 insbesondere von der Förderung durch die Exzellenzinitiative des Bundes (Exzellenzcluster Inflammation at Interfaces). Daneben wurde durch die Deutsche Forschungsgemeinschaft (DFG) seit 2011 unter Federführung der Hautklinik ein Graduiertenkolleg Modulation of Autoimmunity gefördert, das zur Entwicklung des wissenschaftlichen Nachwuchses und zur Ausbildung zahlreicher naturwissenschaftlicher und medizinischer Doktoranden/Doktorandinnen1 beitrug. Seit 2015 besteht an der Klinik auch eine Klinische Forschungsgruppe der DFG zum Thema Pemphigoid Diseases – Molecular Pathways and their Therapeutic Potential. Im Jahr 2018 haben Mitarbeiter der Klinik wesentlich zur Einwerbung eines Clinician Scientist-Programms der DFG beigetragen, das die wissenschaftliche Ausbildung forschender Kliniker verbessern soll. In den letzten Jahren haben sich aus der Lübecker Hautklinik heraus 2 eigenständige Institute neu etabliert. Hierzu zählen das Institut für Entzündungsmedizin unter der Leitung von Prof. Diamant Thaçi, in dem klinische Studien zu entzündlichen Hauterkrankungen initiiert und koordiniert werden und die Versorgung von Patienten mit entzündlichen Dermatosen stattfindet. Daneben ist aus der Hautklinik heraus das Lübecker Institut für Experimentelle Dermatologie (LIED) entstanden, in dem derzeit 5 Professoren mit ihren jeweiligen Arbeitsgruppen zu unterschiedlichen Themen der Entzündung an der Haut forschen. Die interdisziplinären wissenschaftlichen Aktivitäten zur Entzündung an der Haut am Lübecker Campus werden seit 2015 in einem Center for Research on Inflammation of the Skin (CRIS) gebündelt. CRIS erhielt kürzlich die Zusage für ein eigenständiges Forschungsgebäude, das nach § 91 Grundgesetz durch Bund und Land finanziert wird und derzeit im Zentrum des Lübecker Campus entsteht. Der Ausbau der Forschungsstrukturen der Klinik ging mit der Einrichtung von Spezialambulanzen für verschiedene entzündliche Hauterkrankungen, aber auch für die Versorgung von Hautkrebs und chronischen Wunden einher. Die Klinik verfügt über ein zertifiziertes Hautkrebszentrum und ist Teil der Lübecker universitären Gefäß- und Krebszentren. Weitere wichtige Pfeiler der klinischen Versorgung sind zertifizierte diagnostische Einsendelabore für Dermato-Histopathologie und kutane Autoimmunerkrankungen.

Severe bullous pemphigoid associated with pembrolizumab therapy for metastatic melanoma with complete regression

Bullous pemphigoid (BP) is considered to be a humorally mediated autoimmune disease, but autoreactive T-cells and T-regulatory cells (Tregs) have also been implicated in this disease. Tregs and the programmed death-1 (PD-1) : programmed death ligand (PD-L) pathway are both critical in terminating immune response, and elimination of either can result in breakdown of tolerance and development of autoimmunity. We report a patient with metastatic malignant melanoma (MM), who underwent pembrolizumab (anti-PD-1) therapy following unsuccessful treatment with ipilimumab [anti-cytotoxic T-lymphocyte-associated protein (CTLA)-4]. The patient developed BP with increasing serum titres of anti-BP180 IgG autoantibodies and increasing disease severity during pembrolizumab therapy. High doses of corticosteroids and methotrexate were needed to control the BP. Following the termination of pembrolizumab therapy, imaging showed complete regression of all metastatic sites. This result may indicate a crucial role for T-cell suppressive activity in controlling and preventing BP.

Dexamethasone suppresses interleukin-22 associated with bacterial infection in vitro and in vivo

Interleukin (IL)-22 production triggered by innate immune mechanisms has been identified as key to efficient intestinal anti-bacterial host defence and preservation of homeostasis. We hypothesized that glucocorticoid therapy may impair IL-22 expression, which should promote intestinal epithelial damage with the potential of subsequent bacterial translocation. High-dose corticosteroid therapy in Crohn's disease has been associated with an increased rate of abscess formation and ultimately with a higher risk of developing postoperative infectious complications, including abdominal sepsis. Thus, we sought to investigate effects of the prototypic glucocorticoid dexamethasone on IL-22 production in the context of bacterial infection. Enhanced IL-22 plasma levels were detectable in rat sepsis. Moreover, heat-inactivated Staphylococcus epidermidis, used as a prototypic activator of innate immunity, induced robust production of IL-22 by human peripheral blood mononuclear cells (PBMC). Here, we report for the first time that dexamethasone mediates remarkable suppression of IL-22 as detected in S. epidermidis-activated PBMC and rat sepsis, respectively. The data presented herein suggest that insufficient IL-22 function may contribute to impaired intestinal host defence in the context of corticosteroid therapy.

Epicatechin selectively prevents nitration but not oxidation reactions of peroxynitrite

The flavanol (-)-epicatechin has been found to protect against damage inflicted by peroxynitrite, an inflammatory intermediate. Here, epicatechin was tested in systems of increasing complexity. The compound efficiently protected against nitration of protein tyrosine residues by peroxynitrite (IC(50) approximately 0.02 mol epicatechin/mol peroxynitrite). However, at epicatechin concentrations completely preventing nitration of tyrosine by peroxynitrite, protection against the oxidative inactivation of glyceraldehyde-3-phosphate dehydrogenase or soybean lipoxygenase-1 was marginal (IC(50) > 1 mol epicatechin/mol peroxynitrite), approximately two orders of magnitude less. Likewise, epicatechin was relatively ineffective against oxidation of thiols in cell lysates, and against the oxidation of 2',7'-dichlorodihydrofluorescein in cultured cells. The activation of the kinases Akt/protein kinase B, ERK1/2 and p38-MAPK by peroxynitrite in murine aorta endothelial cells was not altered by epicatechin, suggesting that activation of these kinases is due to processes other than tyrosine nitration.