Autoantigen-specific CD4+ T cells acquire an exhausted phenotype and persist in human antigen-specific autoimmune diseases.

Pro-inflammatory autoantigen-specific CD4+ T helper (auto-Th) cells are central orchestrators of autoimmune diseases (AIDs). We aimed to characterize these cells in human AIDs with defined autoantigens by combining human leukocyte antigen (HLA)-tetramer-based and activation-based multidimensional ex vivo analyses. In aquaporin4-antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD) patients, auto-Th cells expressed CD154, but proliferative capacity and pro-inflammatory cytokines were strongly reduced. Instead, exhaustion-associated co-inhibitory receptors were expressed together with FOXP3, the canonical regulatory T cell (Treg) transcription factor. Auto-Th cells responded in vitro to checkpoint inhibition and provided potent B cell help. Cells with the same exhaustion-like (ThEx) phenotype were identified in soluble liver antigen (SLA)-antibody-autoimmune hepatitis and BP180-antibody-positive bullous pemphigoid, AIDs of the liver and skin, respectively. While originally described in cancer and chronic infection, our data point to T cell exhaustion as a common mechanism of adaptation to chronic (self-)stimulation across AID types and link exhausted CD4+ T cells to humoral autoimmune responses, with implications for therapeutic targeting.

Meeting report - Desmosome dysfunction and disease: Alpine desmosome disease meeting.

Desmosome diseases are caused by dysfunction of desmosomes, which anchor intermediate filaments (IFs) at sites of cell-cell adhesion. For many decades, the focus of attention has been on the role of actin filament-associated adherens junctions in development and disease, especially cancer. However, interference with the function of desmosomes, their molecular constituents or their attachments to IFs has now emerged as a major contributor to a variety of diseases affecting different tissues and organs including skin, heart and the digestive tract. The first Alpine desmosome disease meeting (ADDM) held in Grainau, Germany, in October 2022 brought together international researchers from the basic sciences with clinical experts from diverse fields to share and discuss their ideas and concepts on desmosome function and dysfunction in the different cell types involved in desmosome diseases. Besides the prototypic desmosomal diseases pemphigus and arrhythmogenic cardiomyopathy, the role of desmosome dysfunction in inflammatory bowel diseases and eosinophilic esophagitis was discussed.

Bullous pemphigoid induced by IgG targeting type XVII collagen non-NC16A/NC15A extracellular domains is driven by Fc gamma receptor- and complement-mediated effector mechanisms and is ameliorated by neonatal Fc receptor blockade.

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting type XVII collagen (Col17) with the noncollagenous 16A (NC16A) ectodomain representing the immunodominant site. The role of additional extracellular targets of Col17 outside NC16A has not been unequivocally demonstrated. In this study, we showed that Col17 ectodomain-reactive patient sera depleted in NC16A IgG induced dermal-epidermal separation in a cryosection model indicating the pathogenic potential of anti-Col17 non-NC16A extracellular IgG. Moreover, injection of IgG targeting the murine Col17 NC14-1 domains (downstream of NC15A, the murine homologue of human NC16A) into C57BL/6J mice resulted in erythematous skin lesions and erosions. Clinical findings were accompanied by IgG/C3 deposits along the basement membrane and subepidermal blistering with inflammatory infiltrates. Disease development was significantly reduced in either Fc-gamma receptor (FcγR)- or complement-5a receptor-1 (C5aR1)-deficient mice. Inhibition of the neonatal FcR (FcRn), an atypical FcγR regulating IgG homeostasis, with the murine Fc fragment IgG2c-ABDEG, a derivative of efgartigimod, reduced anti-NC14-1 IgG levels, resulting in ameliorated skin inflammation compared with isotype-treated controls. These data demonstrate that the pathogenic effects of IgG targeting the Col17 domain outside human NC16A/murine NC15A are partly attributable to antibody-mediated FcγR- and C5aR1 effector mechanisms while pharmacological inhibition of the FcRn represents a promising treatment for BP. The mouse model of BP will be instrumental in further investigating the role of Col17 non-NC16A/NC15A extracellular epitopes and validating new therapies for this disease. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

C3d-Targeted factor H inhibits tissue complement in disease models and reduces glomerular injury without affecting circulating complement.

Complement-mediated diseases can be treated using systemic inhibitors. However, complement components are abundant in circulation, affecting systemic inhibitors' exposure and efficacy. Furthermore, because of complement's essential role in immunity, systemic treatments raise infection risk in patients. To address these challenges, we developed antibody fusion proteins combining the alternative-pathway complement inhibitor factor H (fH1-5) with an anti-C3d monoclonal antibody (C3d-mAb-2fH). Because C3d is deposited at sites of complement activity, this molecule localizes to tissue complement while minimizing circulating complement engagement. These fusion proteins bind to deposited complement in diseased human skin sections and localize to activated complement in a primate skin injury model. We further explored the pharmacology of C3d-mAb-2fH proteins in rodent models with robust tissue complement activation. Doses of C3d-mAb-2fH >1 mg/kg achieved >75% tissue complement inhibition in mouse and rat injury models while avoiding circulating complement blockade. Glomerular-specific complement inhibition reduced proteinuria and preserved podocyte foot-process architecture in rat membranous nephropathy, indicating disease-modifying efficacy. These data indicate that targeting local tissue complement results in durable and efficacious complement blockade in skin and kidney while avoiding systemic inhibition, suggesting broad applicability of this approach in treating a range of complement-mediated diseases.

Granzyme B inhibition reduces autoantibody-induced dermal-epidermal separation in an ex vivo model of epidermolysis bullosa acquisita.

The pemphigoid disease epidermolysis bullosa acquisita (EBA) is an autoimmune blistering skin disease characterized by autoantibodies against type VII collagen (COL7), immune cell infiltrates at the dermal-epidermal junction and subepidermal blistering. Proteases, particularly granzyme B (GzmB), have been established as therapeutic targets for the treatment of EBA and other pemphigoid diseases. We investigated the impact of the novel GzmB inhibitor SNT-6935 on anti-COL7 IgG-induced subepidermal blistering in a well-established EBA ex vivo model. Our findings demonstrate that pharmacological targeting of GzmB with its selective inhibitor SNT-6935 significantly reduced autoantibody-induced dermal-epidermal separation in human skin cryosections. Interestingly, treatment of skin cryosections with recombinant human GzmB alone did not cause dermal-epidermal separation, suggesting that additional mechanisms alongside GzmB are required for tissue damage in EBA. In conclusion, our study highlights the significant contribution of GzmB to the pathogenesis of EBA and supports the notion of GzmB as a therapeutic target in EBA and other pemphigoid diseases.

Reactivity against the BP180 ectodomain in patients with bullous pemphigoid, mucous membrane pemphigoid, multiple sclerosis and Parkinson disease.

The 16th non-collagenous domain (NC16A) of BP180 is the main antigenic target of autoantibodies in bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP). Commercially available assays detect serum autoantibodies against NC16A in the majority of BP (80%-90%) and in approximately 50% of MMP patients. However, a standardized test system for detecting antibodies against other regions of BP180 is still lacking. Moreover, anti-BP180 autoantibodies have been found in neurological conditions such as multiple sclerosis and Parkinson disease. This study aimed at identifying primary epitopes recognized by BP autoantibodies on the BP180 ectodomain. Serum samples of 51 BP and 30 MMP patients both without anti-NC16A reactivity were included along with 44 multiple sclerosis and 75 Parkinson disease sera. Four overlapping His-tagged proteins covering the entire BP180 ectodomain (BP180(ec)1-4) were cloned, expressed, purified and tested for reactivity by immunoblot. IgG antibodies to BP180(ec)3 were detected in 98% of BP, 77% of MMP and 2% of normal human sera. Only weak reactivity was detected for neurological diseases against BP180(ec)1, BP180(ec)2 and BP180(ec)4, in 3%, 11% and 7% of tested multiple sclerosis sera, respectively. 8% of Parkinson disease sera reacted with BP180(ec)2 and 9% with BP180(ec)4. In conclusion, this study successfully identified epitopes recognized by BP autoantibodies outside the NC16A domain in pemphigoid diseases. These findings contribute to a better understanding of the immune response in BP and MMP with potential implications for a future diagnostic assay for NC16A-negative pemphigoid patients.

Risk of death, major adverse cardiac events and relapse in patients with bullous pemphigoid treated with systemic or topical corticosteroids.

BACKGROUND: According to current guidelines, systemic or topical corticosteroids are both recommended as first-line treatments for bullous pemphigoid (BP). There is evidence to suggest that topical application may be associated with a lower risk of mortality. However, there is a lack of comprehensive large-scale data comparing mortality rates, as well as the risk of major adverse cardiac events (MACE), infections and relapse, between systemic and topical corticosteroid treatments. OBJECTIVES: To evaluate the risk of death, MACE, infections and relapse in patients with BP treated with systemic or topical corticosteroids. METHODS: A population-based retrospective cohort study was performed using the TriNetX US Collaborative Network. As a measure against bias, propensity score matching for age, sex, 10 diseases and 6 medications was done, and 3 sensitivity analyses were conducted. RESULTS: All-time risk of death was increased in US patients with BP exposed to any dose of systemic corticosteroids (n = 2917) vs. patients treated with topical clobetasol propionate [n = 2932; hazard ratio (HR) 1.43, 95% confidence interval (CI) 1.28-1.58 (P < 0.001)]. This was consistent in time-stratified analysis (1- and 3-year mortality rates) and in analysis contrasting prednisone (equivalent) doses of 1-10 mg (low) or 30-100 mg (medium-high) systemic corticosteroid to topical treatment. The increased risk of death in US patients with BP exposed to any dose of systemic corticosteroids vs. topical treatment was accompanied by increased risks for MACE (HR 1.33, 95% CI 1.08-1.64; P = 0.008) and infections (HR 1.33, 95% CI 1.15-1.54; P < 0.001). The risk of continued disease or relapse was decreased in patients treated with systemic vs. topical corticosteroids (HR 0.85, 95% CI 0.77-0.94; P = 0.002). Results regarding mortality and continued disease or relapse persisted in three sensitivity analyses. Potential limitations included the retrospective data collection, bias for treatment selection and miscoding. CONCLUSIONS: Pending validation in prospective studies, where feasible - and despite the heightened risk of relapse - topical corticosteroid treatment may be advantageous over systemic corticosteroid treatment owing to its significantly lower risk of death.

Bullous pemphigoid (BP) is an autoimmune skin disease that commonly affects older people. The recommended treatment is medication called corticosteroids, either taken as a tablet or injection ('systemic') or applied to the skin ('topical'). Some evidence suggests that topical corticosteroids might be safer in terms of the risk of dying. We looked at whether there was a difference between the risk of dying, having heart problems, getting sick or the condition coming back in people with BP who use the different medications. To do this, we used people's past health information and compared people of similar ages and genders, 10 diseases and 6 medications. We found that people with BP who used systemic corticosteroids had a higher chance of dying. This also meant that people taking this form of the medication had a greater chance of having heart problems and getting infections. However, the risk of BP coming back was lower for people who used systemic corticosteroids. Our findings suggest that although there is a higher risk of BP coming back, there may be fewer risks from topical corticosteroids than systemic corticosteroids.

Efficacy and safety of adjuvant immunoadsorption in pemphigus vulgaris and pemphigus foliaceus (IA-Pem Study): a multicentre randomized controlled trial.

BACKGROUND: Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are potentially life-threatening autoimmune blistering diseases. Treatment is based on long-term immunosuppression with high doses of glucocorticosteroids in combination with potentially corticosteroid-sparing agents and/or rituximab. Immunoadsorption (IA) has emerged as a fast-acting adjuvant treatment option. OBJECTIVES: To assess the clinical efficacy of IA in addition to best medical treatment (BMT). METHODS: We conducted a multicentre (26 centres from Germany and Austria) randomized controlled trial in 72 patients with newly diagnosed, relapsed or chronic active PV or PF (34 female patients and 38 male patients, aged 42-72 years) comparing BMT (prednisolone 1.0 mg kg-1 per day plus azathioprine or mycophenolate) with adjuvant IA (BMT + IA). Central 1 : 1 randomization was done at the coordinating centre for clinical trials (KKS Marburg). The primary endpoint was analysed using Kaplan-Meier and Cox regression methods. RESULTS: The study was ended prematurely owing to safety concerns after random allocation of 72 patients to BMT + IA (n = 34) or BMT (n = 38). The primary endpoint, time to complete remission on therapy, was not significantly different for the two groups [hazard ratio (HR) 1.35, 95% confidence interval (CI) 0.68-2.69; P = 0.39]. The cumulative dose of prednisolone was significantly lower in the BMT + IA group compared with BMT alone (difference -1214, 95% CI -2225 to -70; P = 0.03). In a post hoc analysis, patients with more extensive PV/PF showed a tendency towards a shorter time to remission in the BMT + IA group compared with the BMT group (HR 1.87, P = 0.17 in patients with baseline Pemphigus Disease Area Index ≥ 15). While more adverse events were observed in patients in the BMT group (29 vs. 25), severe adverse events were more frequent in patients in the BMT + IA group (17 events in 10 patients vs. 11 events in 8 patients). CONCLUSIONS: In this study, adjuvant IA did not demonstrate a shorter time to clinical remission, but a corticosteroid-sparing effect was observed. In patients with extensive PV/PF, post hoc analysis suggests that adjuvant IA may lead to earlier remission, but potential adverse events must be carefully weighed against the expected benefits.

Pemphigus vulgaris and pemphigus foliaceus are potentially life-threatening autoantibody-driven blistering diseases, which present with erosions or blisters on skin and/or mucous membranes. Treatment is based on long-term immunosuppressive agents. Immunoadsorption (IA) is a procedure that removes autoantibodies from the blood and has emerged as a fast-acting treatment option for pemphigus.We conducted a trial comparing best medical treatment (BMT) (prednisolone 1.0 mg kg per day plus azathioprine or mycophenolate) with best medical treatment plus IA (BMT + IA). A total of 26 centres from Germany and Austria recruited 72 patients with active pemphigus (34 women and 38 men, aged 42­72 years) who were randomly allocated in a ratio of 1 : 1 to the treatment groups.Following inclusion of 72 patients in the BMT + IA (n = 34) or BMT (n = 38) groups, the study ended prematurely owing to safety concerns. The main outcome, time to complete remission (relief of all symptoms) while still receiving therapy, was not significantly different for the two groups. In contrast, the cumulative dose of prednisolone was significantly lower in the BMT + IA compared with BMT alone. In an additional analysis, patients with more extensive pemphigus showed a tendency towards a shorter time to remission in the BMT + IA group compared with the BMT group. While more adverse events were observed in the BMT group (29 vs. 25), severe adverse events were more frequent in the BMT + IA group (17 vs. 11). In this study, IA did not show a shorter time to clinical remission, but a prednisolone-sparing effect was observed. In patients with extensive pemphigus, adjuvant IA may possibly lead to earlier remission, but potential adverse events must be carefully weighed against the expected benefits.

Laminin ß4 is a constituent of the cutaneous basement membrane zone and additional autoantigen of anti-p200 pemphigoid.

BACKGROUND: Anti-p200 pemphigoid is a subepidermal autoimmune blistering disease (AIBD) characterized by autoantibodies against a 200 kDa protein. Laminin γ1 has been described as target antigen in 70% to 90% of patients. No diagnostic assay is widely available for anti-p200 pemphigoid, which might be due to the unclear pathogenic relevance of anti-laminin γ1 autoantibodies. OBJECTIVE: To identify a target antigen with higher clinical and diagnostic relevance. METHODS: Immunoprecipitation, mass spectrometry, and immunoblotting were employed for analysis of skin extracts and sera of patients with anti-p200 pemphigoid (n = 60), other AIBD (n = 33), and healthy blood donors (n = 29). To localize the new antigen in skin, cultured keratinocytes and fibroblasts, quantitative real-time polymerase chain reaction and immunofluorescence microscopy were performed. RESULTS: Laminin ß4 was identified as target antigen of anti-p200 pemphigoid in all analyzed patients. It was located at the level of the basement membrane zone of the skin with predominant expression in keratinocytes. LIMITATIONS: A higher number of sera needs to be tested to verify that laminin ß4 is the diagnostically relevant antigen of anti-p200 pemphigoid. CONCLUSION: The identification of laminin ß4 as an additional target antigen in anti-p200 pemphigoid will allow its differentiation from other AIBD and as such, improve the management of these rare disorders.

S2k guidelines on diagnosis and treatment of linear IgA dermatosis initiated by the European Academy of Dermatology and Venereology.

INTRODUCTION: Linear IgA dermatosis (LAD) is a rare subepidermal autoimmune bullous disease (AIBD) defined by predominant or exclusive immune deposits of immunoglobulin A at the basement membrane zone of skin or mucous membranes. This disorder is a rare, clinically and immunologically heterogeneous disease occurring both in children and in adults. The aim of this project is to present the main clinical features of LAD, to propose a diagnostic algorithm and provide management guidelines based primarily on experts' opinion because of the lack of large methodologically sound clinical studies. METHODS: These guidelines were initiated by the European Academy of Dermatology and Venereology (EADV) Task Force Autoimmune Bullous Diseases (AIBD). To achieve a broad consensus for these S2k consensus-based guidelines, a total of 29 experts from different countries, both European and non-European, including dermatologists, paediatric dermatologists and paediatricians were invited. All members of the guidelines committee agreed to develop consensus-based (S2k) guidelines. Prior to a first virtual consensus meeting, each of the invited authors elaborated a section of the present guidelines focusing on a selected topic, based on the relevant literature. All drafts were circulated among members of the writing group, and recommendations were discussed and voted during two hybrid consensus meetings. RESULTS: The guidelines summarizes evidence-based and expert opinion-based recommendations (S2 level) on the diagnosis and treatment of LAD. CONCLUSION: These guidelines will support dermatologists to improve their knowledge on the diagnosis and management of LAD.

Evaluation of the Diagnostic Value of Oesophageal Biopsies for Direct Immunofluorescence Microscopy in Mucous Membrane Pemphigoid.

Mucous membrane pemphigoid is an autoimmune blistering disorder characterized by predominant involvement of surface-close epithelia and linear depositions of immunoreactants at the dermal-epithelial junction on direct immunofluorescence microscopy. A major diagnostic difficulty is the frequent need for multiple biopsies to facilitate the diagnosis. Although oesophageal involvement is a rare, but life-threatening manifestation, the relevance of oesophageal direct immunofluorescence sampling is unclear. This retrospective monocentric study evaluated 67 non-lesional biopsies from 11 patients with mucous membrane pemphigoid and clinical symptoms suggestive of oesophageal involvement, comprising 31 samples from the oesophagus and 36 samples from other anatomical sites. Five patients (45.5%) exhibited endoscopic findings compatible with oesophageal involvement of mucous membrane pemphigoid. No correlation was identified between the presence of oesophageal lesions and direct immunofluorescence positivity in lesions from the oesophagus (p = 1.0). Oral and cutaneous samples were significantly more frequently positive by direct immunofluorescence than were oesophageal biopsies (p < 0.0001 and p = 0.0195, respectively). Oesophageal samples yielded significantly less IgG reactivity than oral and cutaneous lesions (p < 0.0001 and p = 0.0126, respectively), and less IgA antibody response than oral lesions (p = 0.0036). In conclusion, oesophageal direct immunofluorescence samples were inferior to oral and cutaneous biopsies for the diagnosis of mucous membrane pemphigoid even when oesophageal lesions compatible with mucous membrane pemphigoid were present at the time of biopsy.

Serum reactivity in dermatitis herpetiformis: an international multicentre study.

BACKGROUND: Dermatitis herpetiformis (DH) is a rare gluten-induced skin disorder characterized predominantly by IgA autoantibodies against endomysium, tissue transglutaminase (TG2/tTG), epidermal transglutaminase (TG3/eTG) and deamidated gliadin. To date, circulating autoantibody reactivity has not been systematically described. OBJECTIVES: Characterization of serum reactivities in DH. METHODS: This multicentre international study analysed sera from 242 patients with DH taken at the time of initial diagnosis. DH-specific IgA and IgG serum autoantibodies were analysed by indirect immunofluorescence (IF) on monkey oesophagus, and by enzyme-linked immunosorbent assay (ELISA) based on recombinant TG2/tTG, TG3/eTG and deamidated gliadin (GAF3X). RESULTS: IgA indirect IF microscopy on monkey oesophagus revealed the highest reactivity (84.3%; specificity 100%) followed by IgA TG2/tTG ELISA (78.5%, specificity 99.0%), IgA TG3/eTG ELISA (72.7%, specificity 95.0%) and IgA GAF3X ELISA (69.0%, specificity 98.5%). CONCLUSIONS: Serum IgA and IgG autoantibodies against endomysium, TG2/tTG, TG3/eTG and deamidated gliadin are highly prevalent in DH. Indirect IF microscopy on monkey oesophagus (IgA) provides the highest diagnostic accuracy that can be further enhanced by 4.5% when combined with IgA TG2/tTG ELISA.

Autoimmune bullous dermatoses.

Autoimmune bullous dermatoses (AIBD) are a heterogeneous group of about a dozen diseases characterized clinically by erosions and blisters and immunopathologically by autoantibodies against structural proteins of the skin or transglutaminase 2/3. The diagnosis of AIBD has made tremendous progress in the last decade due to the availability of standardized serological assays that, knowing the clinical picture, allow the diagnosis in the vast majority of patients. The development of various in vitro and in vivo models of the most common AIBD, namely, bullous pemphigoid, pemphigus vulgaris, mucous membrane pemphigoid, and the rare epidermolysis bullosa acquisita, allows identification of key molecules and inflammatory pathways as well as preclinical evaluation of the effect of new anti-inflammatory agents. The approval of rituximab for moderate and severe pemphigus vulgaris and the development of national and international guidelines for the most common AIBD have considerably advanced the care of these patients. Nevertheless, the limited therapeutic armamentarium is the main challenge for the management of AIBD. Several phase II and III randomized controlled clinical trials provide hope for new, effective, and safe therapeutic options in the coming years. This review summarizes the epidemiology, clinic, diagnosis, pathophysiology, and therapy of AIBD and gives an outlook on both current diagnostic and therapeutic needs as well as future developments.

On the Current Care Situation and Treatment of Ocular Mucous Membrane Pemphigoid in Germany. / Zur Versorgungssituation und konservativen Therapie des okulären vernarbenden Schleimhautpemphigoids in Deutschland.

BACKGROUND: Ocular involvement in mucous membrane pemphigoid (MMP) is relatively rare, with a prevalence of 25 cases per million population, equating to approx. 2,100 patients throughout Germany. Diagnosis can be difficult - especially in cases of isolated ocular involvement - and treatment can be complex and lengthy. Immunosuppressants or immunomodulatory drugs are often used. Due to the complexity of diagnosis and treatment, MMP patients are usually referred to specialized centers. The aim of this project was to evaluate the current care situation of patients with ocular MMP in Germany. METHODS: A paper-based survey was designed and sent to all university eye clinics and other specialized centers in Germany in April 2020. The survey asked about the existence of a specialized outpatient service, the total annual number of patients with MMP, the annual number of newly diagnosed patients, any interdisciplinary collaboration for diagnostic or therapeutic purposes, as well as the local and systemic therapy used. RESULTS: Of a total of 44 clinics, 28 (64%) responded, reporting a total average of 27 ± 42 (0 - 200) patients and 3.6 ± 2.2 (0 - 10) new cases per year. This corresponds to a total of 741 patients. Only nine (32%) of the responding clinics offer specialized MMP clinics. 93% of the centers collaborate with the local dermatology department. 79% perform serological and histological diagnostics in-house. About half of the centers (n = 16) apply a standardized treatment regime. Systemic glucocorticoids (66.7%) are most commonly used, followed by mycophenolate mofetil and dapsone (57.1%), rituximab (33.3%), azathioprine and cyclophosphamide (28.6%), as well as methotrexate (19.0%). The least frequently used treatment is intravenous immunoglobulin (14.3%). CONCLUSION: This survey of German ophthalmology departments obtained data from about one third of the estimated total cohort of all patients with MMP in Germany. These are presumed to be exclusively patients with at least one ocular involvement. The complex care of these patients is usually provided in collaboration with a dermatologist and with the use of systemic anti-inflammatory medication. Currently, an ophthalmological MMP register is being established to better record the epidemiology and care situation of this rare disease in Germany and to improve it in the long term.

S2k Guideline for the diagnosis and treatment of mucous membrane pemphigoid.

Mucous membrane pemphigoid (MMP) is a pemphigoid disease with predominant mucous membrane involvement. It mainly affects the mucous membranes of the mouth, eyes, nose and pharynx, but also the larynx, trachea, esophagus, genital and perianal regions. The manifestation of the disease covers a wide spectrum from gingival erythema and single oral lesions to severe tracheal strictures that obstruct breathing and conjunctival scarring with marked visual impairment and, not infrequently, blindness. In addition to a clinical picture of predominant mucosal involvement, diagnosis is based on direct immunofluorescence of a peri-lesional biopsy and serology. The main target antigen is BP180 (collagen XVII), and reactivity with laminin 332 is associated with malignancy in approximately 25 % of MMP patients. The treatment of MMP is challenging. On the one hand, due to the involvement of different mucous membranes, good interdisciplinary cooperation is required; on the other hand, due to the rarity of the disease, no randomized controlled clinical trials are available. The aim of this guideline is to present the clinical picture, including severity and scoring systems, and to give guidance for diagnosing and treating this complex disease. In MMP, interdisciplinary cooperation plays an essential role as well as the prompt diagnosis and initiation of adequate therapy in order to avoid irreversible damage to the mucous membranes with serious complications.

Genetic association and differential expression of HLAComplexGroup lncRNAs in pemphigus.

BACKGROUND: Pemphigus is a group of bullous diseases characterized by acantholysis and skin blisters. As for other autoimmune diseases, the strongest genetic associations found so far for pemphigus foliaceus (PF) and vulgaris (PV) are with alleles of HLA genes. However, apart from protein-coding genes, the MHC region includes a set of poorly explored long non-coding RNA (lncRNA) genes, the HLA complex group (HCG). OBJECTIVES: To investigate if HCG lncRNA alleles are associated with pemphigus susceptibility. METHODS AND RESULTS: We analyzed SNPs in 13 HCG lncRNA genes, both in PV (Germany: 241 patients; 1,188 controls) and endemic PF (Brazil: 227 patients; 194 controls), applying multivariate logistic regression. We found 55 associations with PV (pcorr < 0.01) and nine with endemic PF (pcorr < 0.05), the majority located in TSBP1-AS1 (which includes HCG23) and HCG27 lncRNA genes, independently of HLA alleles previously associated with pemphigus. The association of TSBP1-AS1 rs3129949*A allele was further replicated in sporadic PF (p = 0.027, OR = 0.054; 75 patients and 150 controls, all from Germany). Next, we evaluated the expression levels of TSBP1-AS1, TSBP1, HCG23, and HCG27 in blood mononuclear cells of Brazilian patients and controls. HCG27 was upregulated in endemic PF (p = 0.035, log2 FC = 1.3), while TSBP1-AS1 was downregulated in PV (p = 0.029, log2 FC = -1.29). The same expression patterns were also seen in cultured keratinocytes stimulated with IgG antibodies from patients and controls from Germany. TSBP1 mRNA levels were also decreased in endemic PF blood cells (p = 0.042, log2 FC = -2.14). TSBP1-AS1 and HCG27 were also observed downregulated in CD19+ cells of endemic PF (p < 0.01, log2 FC = -0.226 and -0.46 respectively). CONCLUSIONS: HCG lncRNAs are associated with susceptibility to pemphigus, being TSBP1-AS1 and HCG27 also differentially expressed in distinct cell populations. These results suggest a role for HCG lncRNAs in pemphigus autoimmunity.

Genetic variability of immune-related lncRNAs: polymorphisms in LINC-PINT and LY86-AS1 are associated with pemphigus foliaceus susceptibility.

Pemphigus foliaceus (PF) is an autoimmune blistering disease of the skin, clinically characterized by erosions and, histopathologically, by acantholysis. PF is endemic in the Brazilian Central-Western region. Numerous single nucleotide polymorphisms (SNPs) have been shown to affect the susceptibility for PF, including SNPs at long non-coding RNA (lncRNA) genes, which are known to participate in many physiological and pathogenic processes, such as autoimmunity. Here, we investigated whether the genetic variation of immune-related lncRNA genes affects the risk for endemic and sporadic forms of PF. We analysed 692 novel SNPs for PF from 135 immune-related lncRNA genes in 227 endemic PF patients and 194 controls. The SNPs were genotyped by Illumina microarray and analysed by applying logistic regression at additive model, with correction for sex and population structure. Six associated SNPs were also evaluated in an independent German cohort of 76 sporadic PF patients and 150 controls. Further, we measured the expression levels of two associated lncRNA genes (LINC-PINT and LY86-AS1) by quantitative PCR, stratified by genotypes, in peripheral blood mononuclear cells of healthy subjects. We found 27 SNPs in 11 lncRNA genes associated with endemic PF (p < .05 without overlapping with protein-coding genes). Among them, the LINC-PINT SNP rs10228040*A (OR = 1.47, p = .012) was also associated with increased susceptibility for sporadic PF (OR = 2.28, p = .002). Moreover, the A+ carriers of LY86-AS1*rs12192707 mark lowest LY86-AS1 RNA levels, which might be associated with a decreasing autoimmune response. Our results suggest a critical role of lncRNA variants in immunopathogenesis of both PF endemic and sporadic forms.

The risk of COVID-19 in patients with bullous pemphigoid and pemphigus: A population-based cohort study.

BACKGROUND: The burden of COVID-19 in patients with bullous pemphigoid (BP) and pemphigus is yet to be evaluated. OBJECTIVE: To assess the risks of COVID-19 and COVID-19-associated hospitalization and mortality in patients with BP and pemphigus and to delineate determinants of severe COVID-19 illness among these patients. METHODS: A population-based cohort study compared COVID-19 and its complications in patients with BP (n = 1845) and pemphigus (n = 1236) with age-, sex-, and ethnicity-matched control subjects. RESULTS: The risks of COVID-19 (hazard rate [HR], 1.12; 95% confidence interval [CI], 0.72-1.73; P = .691) and COVID-19-associated hospitalization (HR, 1.58; 95% CI, 0.84-2.98; P = .160) was comparable between patients with BP and controls. The risk of COVID-19-associated mortality was higher among patients with BP (HR, 2.82; 95% CI, 1.15-6.92; P = .023). The risk of COVID-19 (HR, 0.81; 95% CI, 0.44-1.49; P = .496), COVID-19-associated hospitalization (HR, 1.41; 95% CI, 0.53-3.76; P = .499), and COVID-19-associated mortality (HR, 1.33; 95% CI, 0.15-11.92; P = .789) was similar in patients with pemphigus and their controls. Systemic corticosteroids and immunosuppressants did not predispose COVID-19-positive BP and pemphigus patients to a more severe illness. LIMITATIONS: Retrospective data collection. CONCLUSIONS: Patients with BP experience increased COVID-19-associated mortality and should be monitored closely. Maintaining systemic corticosteroids and immunosuppressive adjuvant agents during the pandemic is not associated with worse outcomes.

Immunoglobulin M pemphigoid.

BACKGROUND: Pemphigoid diseases are a heterogeneous group of autoimmune blistering disorders characterized by predominant deposition of immunoglobulin G or immunoglobulin A autoantibodies against structural proteins of the dermoepidermal junction (DEJ). Sole linear immunoglobulin M (IgM) deposits at the DEJ in pemphigoid diseases have been observed; however, IgM-specific target antigens have not been identified. OBJECTIVE: Characterization of patients with IgM pemphigoid. METHODS: Skin biopsy specimens and sera from IgM-positive patients were assessed using histopathology, direct and indirect immunofluorescence microscopy, enzyme-linked immunosorbent assays, immunoblotting, cryosection assay, complement fixation test, and internalization assays. RESULTS: Tissue-bound linear IgM deposits along the DEJ and circulating IgM autoantibodies against type XVII collagen (Col17) were detected. These circulating IgM autoantibodies showed no complement activating or blister inducing capacity, but the ability of Col17 internalization ex vivo. LIMITATIONS: Limited number of patients. CONCLUSION: This study provides further evidence for the role of IgM autoantibodies in pemphigoid disease and highlights Col17 as a target antigen in IgM pemphigoid.

Diagnostic Value and Practicability of Serration Pattern Analysis by Direct Immunofluorescence Microscopy in Pemphigoid Diseases.

In pemphigoid diseases, direct immunofluorescence can be used to differentiate 2 patterns of antibody deposition at the dermal-epidermal junction; u- and n-serrated pattern. The u-serrated pattern is found in epidermolysis bullosa acquisita, and n-serrated pattern in all other pemphigoid diseases. To determine the detection frequency of these serrated patterns and the optimal thickness of biopsy cryosections, 2 patient cohorts obtained form our routine autoimmune laboratory were analysed; a retrospective cohort (n = 226) and a prospective cohort (n = 156). [AQ1] In 76% (291/382) of biopsies, a pattern was recog-nized, of which 96% (278/291) and 4% (13/291) had an n- or u-serrated pattern, respectively. A u-serrated pattern was seen in all epidermolysis bullosa acquisita biopsies confirmed by serology. No antibodies against type VII collagen were detected in any of the sera from biopsies with n-serrated pattern. No differences between the detection frequencies of serrated pattern were seen with respect to age, sex, biopsy site, or section thickness, while the detection frequency was higher in patients with serum anti-BP180 reactivity compared with those without. In conclusion, serrated pattern analysis using direct immunofluorescence has a high detection frequency and specificity for epidermolysis bullosa acquisita and will further facilitate the diagnosis of latter disorder.