Pemphigus

The efficacy and safety of low-dose rituximab in the treatment of pemphigus vulgaris: a cohort study

BACKGROUND

Rituximab (RTX) is considered the first-line treatment for pemphigus vulgaris (PV), which is a B-cell-mediated acquired autoimmune disease. However, no consensus on the optimum dosage has been achieved.

OBJECTIVES

To investigate the efficacy and safety of low-dose RTX (a single infusion of 500 mg) for the treatment of PV, a cohort study was conducted for patients with PV, along with a 12-month follow-up following the administration of RTX.

METHODS

Patients with moderate or severe PV were divided into group A (low-dose RTX combined with corticosteroids) and group B (corticosteroids alone). Data on complete remission (CR) rates, doses of corticosteroids, cumulative doses of corticosteroids at the third, sixth, and twelfth months, pemphigus disease area index and adverse effects (AEs) were collected.

RESULTS

Forty-four patients with moderate or severe PV were enrolled in this study (19 in group A and 25 in group B). Patients treated with low-dose RTX had higher CR rates, lower doses of corticosteroids at the third, sixth, and twelfth months, lower cumulative doses of corticosteroids at the sixth and twelfth months, and fewer AEs than those who received corticosteroids alone.

CONCLUSIONS

This study indicated that low-dose RTX may be a beneficial and secure therapy option for patients with moderate to severe PV.

Epidemiology of malignant tumors in patients with pemphigus: an analysis of trends from 1955 to 2021

BACKGROUND

The incidence of malignant tumors has increased in patients with non-paraneoplastic pemphigus, although there has been no systematic analysis of global epidemiology.

OBJECTIVE

To explore the epidemiology of various types of non-paraneoplastic pemphigus associated with malignant tumors.

METHODS

Five databases from establishment through October 20, 2023, were searched. STATA SE 17 was used for the data analysis. Subgroup, meta-regression, and sensitivity analyses were used to evaluate the heterogeneity of pooled studies.

RESULTS

A total of 6679 participants were included in our meta-analysis from 16 studies. The aggregated prevalence of tumors in patients diagnosed with pemphigus was 8%. The prevalence was 7% in patients with pemphigus vulgaris, 10% in those with pemphigus foliaceus, and 12% in individuals diagnosed with other types of pemphigus. The prevalence was 8% in Asia, 11% in Europe, and 8% in North America. From a country-specific perspective, patients with pemphigus from Israel, Greece, and Germany exhibited a higher prevalence of tumors at 11%. Furthermore, when categorized by the duration of the study period, the highest prevalence was observed in studies spanning 10 to 20 years, at 11%.

CONCLUSION

These findings demonstrate the incidence and prevalence of malignant tumors in patients with non-paraneoplastic pemphigus, which may achieve early detection and intervention, and then reduce mortality rates.

Mild cognitive impairment in pemphigus

BACKGROUND

Pemphigus is a group of autoimmune blistering disorders that have been associated with dementia in previous studies. Mild cognitive impairment (MCI) can be the first stage of progression into dementia. The objective of the present study was to evaluate the frequency of MCI in pemphigus patients compared to a control group.

METHODS

This case-control study included 80 patients with pemphigus referred to the dermatology clinics of Shohadaye Tajrish and Loghman Hakim hospitals, Tehran, Iran, in 2021. A group of 80 individuals without pemphigus who visited the same clinics for cosmetic consultation or interventions were regarded as controls. Age, sex, marital status, and education were recorded for all participants. Disease duration, medications, and severity were noted for pemphigus patients. The Persian version of the Montreal Cognitive Assessment (MoCA) test was used to assess cognitive function.

RESULTS

MCI was significantly more frequent in pemphigus patients than in controls (55% vs. 37.5%, P = 0.026). Furthermore, the total MoCA score was significantly lower in pemphigus patients compared to controls (23.98 ± 3.77 vs. 25.21 ± 3.45, P = 0.032); however, among MoCA's different domains, only the executive functions score was significantly lower in pemphigus patients (P = 0.010). After adjustment, multivariable logistic regression analysis revealed that every 1-year higher education in patients decreased the odds of MCI by 52% (adjusted odds ratio = 0.483, 95% confidence interval 0.326; 0.715, P < 0.001).

CONCLUSIONS

The frequency of MCI was found to be significantly higher, and overall scores of the MoCA test, as well as its executive function domain, were significantly lower among pemphigus patients in this study compared to the control group. Additionally, a higher level of education was associated with decreased odds of MCI in pemphigus patients. Identifying pemphigus patients with MCI through the use of the MoCA test can facilitate early intervention, enabling them to seek help and support.

Desmosomal hyper-adhesion affects direct inhibition of desmoglein interactions in pemphigus

During differentiation, keratinocytes acquire a strong, hyper-adhesive state, where desmosomal cadherins interact Ca2+-independently. Previous data indicate that hyper-adhesion protects keratinocytes from pemphigus vulgaris autoantibody (PV-IgG)-induced loss of intercellular adhesion although the underlying mechanism remains to be elucidated. Thus, we here investigated the effect of hyper-adhesion on PV-IgG-induced direct inhibition of desmoglein (Dsg) 3 interactions by atomic force microscopy. Hyper-adhesion abolished loss of intercellular adhesion and corresponding morphological changes of all pathogenic antibodies used. Pemphigus autoantibodies putatively targeting several parts of the Dsg3 extracellular domain (ECD) and 2G4, targeting a membrane-proximal domain of Dsg3, induced direct inhibition of Dsg3 interactions only in non-hyper-adhesive keratinocytes. In contrast, AK23, targeting the N-terminal ECD1 of Dsg3, caused direct inhibition under both adhesive states. However, antibody binding to desmosomal cadherins was not different between the distinct pathogenic antibodies used and was not changed during acquisition of hyper-adhesion. Additionally, heterophilic Dsc3-Dsg3 and Dsg2-Dsg3 interactions did not cause reduced susceptibility to direct inhibition under hyper-adhesive condition in wt keratinocytes. Taken together, the data suggest that hyper-adhesion reduces susceptibility to autoantibody-induced direct inhibition in dependency on autoantibody-targeted ECD but also demonstrate that further mechanisms are required for the protective effect of desmosomal hyper-adhesion in PV.

[Paraneoplastic pemphigus with underlying Castleman's disease in a 16-year-old girl]

Paraneoplastic pemphigus is a rare, life-threatening autoimmune disease that is clinically characterized by mostly extensive and refractory mucosal erosions and polymorphous skin lesions. We report here on a 16-year-old girl with isolated oral erosions, in whom mucosal pemphigoid was initially suspected and after treatment with prednisolone and dapsone marked improvement was achieved. However, a few months later the patient developed massive respiratory insufficiency as a result of bronchiolitis obliterans, so that a lung transplant was planned. As part of the preparatory diagnostic workup, unicentric, abdominally localized Castleman's disease was diagnosed, which ultimately led to the diagnosis of paraneoplastic pemphigus as evidenced by envoplakin autoantibodies. Tumor resection and subsequent lung transplantation achieved good results with sustained mucocutaneous remission.

Efgartigimod as a novel FcRn inhibitor for autoimmune disease

Immunoglobulin G (IgG) autoantibodies can lead to the formation of autoimmune diseases through Fab and/or Fc-mediated interactions with host molecules as well as activated T cells. The neonatal Fc receptor (FcRn) binds at acidic pH IgG and albumin, and the mechanism for prolonging serum IgG half-life is making IgG re-entry into circulation by prompting it not to be degraded by lysosomes and back to the cell surface. Given the FcRn receptor's essential role in IgG homeostasis, one of the strategies to promote the quick degradation of endogenous IgG is to suppress the function of FcRn, which is beneficial to the treatment of IgG-driven autoimmune disorders like myasthenia gravis (MG), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), stiff person syndrome, and immune thrombocytopenia (ITP). We elaborately read the literature about efgartigimod and systematically reviewed the research progress and clinical application of this novel FcRn inhibitor in autoimmune diseases. Efgartigimod is the firstly FcRn antagonist developed and was approved on 17 December 2021 by the United States for the therapy of acetylcholine receptor-positive MG. In January 2022, efgartigimod received its second regulatory approval in Japan. In addition, the market authorization application in Europe was submitted and validated in August 2021. China's National Medical Products Administration officially accepted the marketing application of efgartigimod on July 13, 2022. To suppress the function of FcRn, which is beneficial to the treatment of IgG-driven autoimmune disorders like MG, CIDP, ITP, and stiff person syndrome. We review the rationale, clinical evidence, and future perspectives of efgartigimod for the treatment of autoimmune disease.

EGFR Inhibition by Erlotinib Rescues Desmosome Ultrastructure and Keratin Anchorage and Protects Against Pemphigus Vulgaris IgG-Induced Acantholysis in Human Epidermis

Pemphigus is a severe blistering disease caused by autoantibodies primarily against the desmosomal cadherins desmoglein (DSG)1 and DSG3 which impair desmosome integrity. Especially for the acute phase, additional treatment options allowing to reduce corticosteroids would fulfill an unmet medical need. Here, we provide evidence that epidermal growth factor receptor (EGFR) inhibition by erlotinib ameliorates pemphigus vulgaris immunoglobulin G (PV-IgG) -induced acantholysis in intact human epidermis. PV-IgG caused phosphorylation of EGFR (Y845) and SRC in human epidermis. In line with that, a phosphotyrosine kinome analysis revealed a robust response associated with EGFR and SRC family kinase signaling in response to PV-IgG but not pemphigus foliaceus autoantibodies. Erlotinib inhibited PV-IgG-induced epidermal blistering and EGFR phosphorylation, loss of desmosomes as well as ultrastructural alterations of desmosome size, plaque symmetry, keratin filament insertion and restored the desmosome midline considered as hallmark of mature desmosomes. Erlotinib enhanced both single molecule DSG3 binding frequency and strength and delayed DSG3 fluorescence recovery supporting that EGFR inhibition increases DSG3 availability and cytoskeletal anchorage. Our data indicate that EGFR is a promising target for pemphigus therapy due to its link to several signaling pathways known to be involved in pemphigus pathogenesis.

Exploring the depths of IgG4: insights into autoimmunity and novel treatments

IgG4 subclass antibodies represent the rarest subclass of IgG antibodies, comprising only 3-5% of antibodies circulating in the bloodstream. These antibodies possess unique structural features, notably their ability to undergo a process known as fragment-antigen binding (Fab)-arm exchange, wherein they exchange half-molecules with other IgG4 antibodies. Functionally, IgG4 antibodies primarily block and exert immunomodulatory effects, particularly in the context of IgE isotype-mediated hypersensitivity reactions. In the context of disease, IgG4 antibodies are prominently observed in various autoimmune diseases combined under the term IgG4 autoimmune diseases (IgG4-AID). These diseases include myasthenia gravis (MG) with autoantibodies against muscle-specific tyrosine kinase (MuSK), nodo-paranodopathies with autoantibodies against paranodal and nodal proteins, pemphigus vulgaris and foliaceus with antibodies against desmoglein and encephalitis with antibodies against LGI1/CASPR2. Additionally, IgG4 antibodies are a prominent feature in the rare entity of IgG4 related disease (IgG4-RD). Intriguingly, both IgG4-AID and IgG4-RD demonstrate a remarkable responsiveness to anti-CD20-mediated B cell depletion therapy (BCDT), suggesting shared underlying immunopathologies. This review aims to provide a comprehensive exploration of B cells, antibody subclasses, and their general properties before examining the distinctive characteristics of IgG4 subclass antibodies in the context of health, IgG4-AID and IgG4-RD. Furthermore, we will examine potential therapeutic strategies for these conditions, with a special focus on leveraging insights gained from anti-CD20-mediated BCDT. Through this analysis, we aim to enhance our understanding of the pathogenesis of IgG4-mediated diseases and identify promising possibilities for targeted therapeutic intervention.

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.

Focus on pemphigus treatment publications: A bibliometric and visual analysis (1992-2022)

Pemphigus is a chronic recurrent disease in dermatology. Although it is not very common, its treatment has been an increasing concern in recent years because it is difficult and long-lasting. At present, there are many papers on pemphigus treatment, and to better understand the research trends and research frontiers of pemphigus treatment, it is necessary to conduct a comprehensive systematic review and analysis. We combined bibliometric and visualization methods to analyze 1365 papers published in the Web of Science database from 1992 to 2022, including basic information about countries, institutions and authors, to gain a general understanding of the treatment of pemphigus. Among them, the United States is the country with the most output, Iran's Tehran University of Medical Sciences is the institution with the most published works, and Ahmed, A. Razzaque of Tufts University is the most influential scholar. In addition, we also learned about the research hotspots and frontiers of pemphigus treatment through a series of analyses on the frequency, clustering, keywords bursts and cited literature, and we briefly reviewed the highly cited literature. We found that the current research focuses in the study of pemphigus treatment are the types, pathogenesis, and treatment of pemphigus, including glucocorticoids, immunosuppressants and many other major treatment methods. Hailey-Hailey disease, genetic susceptibility, and traditional Chinese medicine are potential research hotspots. Rituximab is a research frontier. In conclusion, we hope to provide new research ideas for promoting the development of pemphigus treatment.

Infections in the era of immunobiologicals

Immunobiologicals represent an innovative therapeutic option in dermatology. They are indicated in severe and refractory cases of different diseases when there is contraindication, intolerance, or failure of conventional systemic therapy and in cases with significant impairment of patient quality of life. The main immunobiologicals used in dermatology basically include inhibitors of tumor necrosis factor-alpha (anti-TNF), inhibitors of interleukin-12 and -23 (anti-IL12/23), inhibitors of interleukin-17 and its receptor (anti-IL17), inhibitors of interleukin-23 (anti-IL23), rituximab (anti-CD20 antibody), dupilumab (anti-IL4/IL13) and intravenous immunoglobulin. Their immunomodulatory action may be associated with an increase in the risk of infections in the short and long term, and each case must be assessed individually, according to the risk inherent to the drug, the patient general condition, and the need for precautions. This article will discuss the main risks of infection associated with the use of immunobiologicals, addressing the risk in immunocompetent and immunosuppressed patients, vaccination, fungal infections, tuberculosis, leprosy, and viral hepatitis, and how to manage the patient in the most diverse scenarios.

New-onset of pemphigus following COVID-19 infection: A case report

COVID-19 has been implicated in various cutaneous autoimmune diseases. Pemphigus is a group of autoimmune blistering diseases that target the desmosomal complexes. Pemphigus triggered by COVID-19 has been seldom reported in the literature and remains both a diagnostic and therapeutic challenge. We report a case of COVID-19-induced pemphigus that responded well to prednisone and mycophenolate mofetil after 9 months from initial presentation. On histologic examination, both intercellular and basement membrane staining were noted. Indirect immunofluorescence staining was positive against the intercellular cement of the stratified epithelium from monkey esophagus. We hypothesize that COVID-19 stimulated the release of multiple pemphigus antigens, which resulted in the unusual histologic pattern reported in the present case. Although malignancy should be suspected when features of paraneoplastic pemphigus, such as basement membrane staining on direct immunofluorescence, are noted, it may also be a histologic pattern of pemphigus secondary to COVID-19 that clinicians may consider.

Single-Cell Transcriptomes and Immune Repertoires Reveal the Cell State and Molecular Changes in Pemphigus Vulgaris

The etiology and pathogenesis of pemphigus vulgaris (PV) entail intricate interactions between immune cells and epithelial cells. However, the specific subtypes of immune cells involved in PV, along with their respective roles, remain elusive. Likewise, the precise functions and mechanisms by which glucocorticoids affect cell types within the disease context require further elucidation. To address these knowledge gaps, we performed 5' single-cell RNA sequencing, combined with V(D)J enrichment on buccal mucosal lesions and peripheral blood samples from treatment-naive patients with PV, in conjunction with post-treatment peripheral blood samples obtained after oral prednisone treatment. Our findings suggest that the IL-1α signaling pathway, myeloid APCs, inflammatory CD8+ resident memory T cells, and dysfunctional CD4+ regulatory T cells are involved in the pathogenesis of PV. Part of these findings were validated by immunohistochemical assays and multiplex immunofluorescence assays. Furthermore, our results highlight the significant impact of prednisone treatment on monocytes and mucosal-associated invariant T cells while revealing a limited effect on CD4+ regulatory T cells. Additionally, we present the CDR3 amino acid sequence of BCR related to PV disease and investigate the characteristics of TCR/BCR clonotypes. In conclusion, our study provides a comprehensive understanding of PV, particularly focusing on the mucosal-dominant type, and sheds light on the effects of glucocorticoids within the PV context. These insights hold promise for the development of new therapeutic strategies in this autoimmune disorder.

Ofatumumab subcutaneous injection successfully treated patients with pemphigus vulgaris relapse post rituximab

The therapeutic strategy for the treatment of pemphigus vulgaris (PV) still needs optimization because of the multiple deficiencies of glucocorticoid and rituximab. Ofatumumab, another CD20 monoclonal antibody administrated subcutaneously, provides a possible alternative option. In this study, three patients experienced PV relapse after clinical remission induced by rituximab. With written informed consent, they received an ofatumumab (20 mg) subcutaneous injection twice (2 weeks apart) in combination with a prednisone dose adjusted according to their weight and disease severity. Over the 24-week observation, two of three patients achieved lesion clear-up under prednisone (0.2 mg/kg per day), and the other patient's pemphigus disease area index dropped from 39 to 3 with prednisone (15 mg/day). The anti-desmoglein antibody levels and CD19+ B cell counts declined compared to those at baseline. No severe adverse events were observed within the 24-week follow-up. In summary, we propose a protocol of ofatumumab for patients with refractory PV and report positive treatment outcomes of three patients who received this regimen.

Restoring immune tolerance in pemphigus vulgaris

Intravenous immunoglobulin (IVIg), a preparation of polyclonal serum IgG pooled from numerous blood donors, has been used for nearly three decades and is proving to be an efficient treatment for many autoimmune blistering diseases, including pemphigus vulgaris (PV). Despite its widespread use and therapeutic success, its mechanisms of action are not completely understood. Some of its anti-inflammatory and immunomodulatory actions have been studied. In this study, the authors present a twenty-year follow-up of 21 patients with clinical and immunopathological confirmed PV, treated with IVIg as monotherapy, according to an established published protocol. IVIg therapy produced long-term sustained, clinical, serological, and immunopathological remission. For 20 y, these patients received no drugs and experienced no disease. This observation suggests that there was the establishment of immune balance or restoration of immune regulation in these PV patients. Twelve (57%) patients experienced no relapse during follow-up. Six (29%) patients experienced a relapse due to acute stress or post-coronavirus infection and/or vaccination. Reinstitution of IVIg resulted in prompt sustained recovery. Three (14.2%) patients, in clinical and serological remission, died due to unrelated causes. No severe adverse effects from IVIg were documented in all 21 patients. The simultaneous or sequential anti-inflammatory and immunomodulatory effects of IVIg may have influenced the long-term clinical remission observed. This study provides a human prototype to examine the pathophysiology of autoimmunity and a model to study immune regulation and mechanisms that can facilitate restoring immune tolerance.

Pregnancy in pemphigus vulgaris: A systematic review

PROBLEM

Pemphigus vulgaris may worsen during pregnancy, leading to both maternal and fetal complications. The relationship between pemphigus vulgaris and pregnancy remains unclear, and the outcomes and treatments of pemphigus vulgaris during pregnancy have not been extensively discussed.

METHOD OF STUDY

This article systematically reviews the literature, focusing on the relationship between pemphigus vulgaris and pregnancy. We conducted comprehensive searches in PubMed, Embase, Cochrane Library, and Web of Science databases, identifying 42 studies reporting the disease course, pregnancy outcomes, and management of both pregnancy and pemphigus vulgaris.

RESULTS

A total of 57 cases were included in the analysis, categorized into three distinct forms: pemphigus vulgaris onset before pregnancy (n = 33), onset during pregnancy (n = 20), and onset during the postpartum period (n = 4). Fifty four cases reported treatment strategies, among them, 44 cases (81.5%) initially received systemic corticosteroid therapy during pregnancy. Out of these cases, 7 (15.9%) did not achieve successful remission and required alternative treatment approaches. In terms of pregnancy outcomes, 23 out of 62 neonates (37.1%) exhibited skin lesions or tested positive for anti-dsg IgG in their serum, while 16 neonates (25.8%) experienced other complications.

CONCLUSIONS

These findings highlight the importance of effectively managing pemphigus vulgaris during pregnancy to ensure optimal outcomes.

Integrative single-cell analysis reveals distinct adaptive immune signatures in the cutaneous lesions of pemphigus

Pemphigus, an autoimmune bullous disease affecting the skin and mucosal membranes, is primarily driven by anti-desmoglein (Dsg) autoantibodies. However, the underlying immune mechanisms of this disease remain largely elusive. Here, we compile an unbiased atlas of immune cells in pemphigus cutaneous lesions at single-cell resolution. We reveal clonally expanded antibody-secreting cells (ASCs) that exhibit variable hypermutation and accumulation of IgG4 class-switching in their immunoglobulin genes. Importantly, pathogenic Dsg-specific ASCs are localized within pemphigus lesions and can evolve from both Dsg-autoreactive and non-binding precursors. We observe an altered distribution of CD4+ T cell subsets within pemphigus lesions, including an imbalance of Th17/Th2 cells. Significantly, we identify a distinct subpopulation of Th17 cells expressing CXCL13 and IL-21 within pemphigus lesions, implying its pivotal role in B cell recruitment and local production of autoantibodies. Furthermore, we characterize multiple clonally expanded CD8+ subpopulations, including effector GMZB+ and GMZK+ subsets with augmented cytotoxic activities, within pemphigus lesions. Chemokine-receptor mapping uncovers cell-type-specific signaling programs involved in the recruitment of T/B cells within pemphigus lesions. Our findings significantly contribute to advancing the understanding of the heterogeneous immune microenvironment and the pathogenesis of pemphigus cutaneous lesions, thereby providing valuable insights for potential therapeutic interventions in this disease.

The role of Interleukin-21 in autoimmune Diseases: Mechanisms, therapeutic Implications, and future directions

IL-21 is a multifunctional cytokine that regulates the functional activity of various immune cells. Initial studies have shown that IL-21 can influence the differentiation, proliferation and function of T and B cells, as well as promote the maturation and increase the cytotoxicity of CD8 + T cells and NK cells. During humoral immune responses, IL-21 has significant effects on B cell activation, differentiation and apoptosis. In addition, IL-21 promotes the differentiation of both naive and memory B cells, ultimately leading to the activation of plasma cells. The function of IL-21 in the immune system is complex, as it has the ability to either stimulate or inhibit immune responses. in addition, IL-21 facilitates the differentiation of naive and memory B cells into plasma cells. The functionality of IL-21 in the immune system is diverse, as it has the ability to stimulate or inhibit immune responses. This cytokine has been implicated in several diseases including cancer, allergies and autoimmune diseases. Research has suggested that this cytokine is involved in the development of autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. Several studies have suggested that inhibition of IL-21 has a therapeutic effect on autoimmune diseases. Therefore, targeting both the cytokine's receptor and IL-21 in autoimmune diseases may be an effective approach to reduce the severity of the disease or to treat it. This review will examine the biological effects of IL-21 on various immune cells and the role of the cytokine in autoimmune diseases.

The complicated use of dupilumab in the treatment of atypical generalized pemphigus Erythematous: A report of two cases

Pemphigus is a rare autoimmune disease and has the potential to be fatal without treatment. Pemphigus erythematosus (PE) is a benign type of pemphigus foliaceus. Glucocorticoids and immunosuppressive agents are primary therapeutic modalities in pemphigus erythematosus, which may lead to considerable side effects. There is a growing need for new pemphigus therapies with fewer adverse effects. Dupilumab is a humanized monoclonal IgG4 antibody that inhibits the signaling of interleukin-4 (IL-4) and interleukin-13 (IL-13) and has been applied for atopic dermatitis and asthma. Recently, dupilumab was thought to be beneficial in aggressive refractory pemphigus vulgaris. We report two cases: a 39-year-old male and a 59-year-old woman diagnosed with PE with atypical clinical features. With dupilumab, patients' skin lesions significantly improved, and suitable maintenance glucocorticosteroid doses were reached. In conclusion, we reported the short-term effectiveness and safety of dupilumab in two cases of atypical generalized PE. As an adjunct, such a biologic agent is expected to be efficacious in pemphigus erythematosus.

Genetic Association and Differential RNA Expression of Histone (De)Acetylation-Related Genes in Pemphigus Foliaceus-A Possible Epigenetic Effect in the Autoimmune Response

Pemphigus foliaceus (PF) is an autoimmune skin blistering disease characterized by antidesmoglein-1 IgG production, with an endemic form (EPF) in Brazil. Genetic and epigenetic factors have been associated with EPF, but its etiology is still not fully understood. To evaluate the genetic association of histone (de)acetylation-related genes with EPF susceptibility, we evaluated 785 polymorphisms from 144 genes, for 227 EPF patients and 194 controls. Carriers of HDAC4_rs4852054*A were more susceptible (OR = 1.79, p = 0.0038), whereas those with GSE1_rs13339618*A (OR = 0.57, p = 0.0011) and homozygotes for PHF21A_rs4756055*A (OR = 0.39, p = 0.0006) were less susceptible to EPF. These variants were not associated with sporadic PF (SPF) in German samples of 75 SPF patients and 150 controls, possibly reflecting differences in SPF and EPF pathophysiology. We further evaluated the expression of histone (de)acetylation-related genes in CD4+ T lymphocytes, using RNAseq. In these cells, we found a higher expression of KAT2B, PHF20, and ZEB2 and lower expression of KAT14 and JAD1 in patients with active EPF without treatment compared to controls from endemic regions. The encoded proteins cause epigenetic modifications related to immune cell differentiation and cell death, possibly affecting the immune response in patients with PF.

Epidemiological Study of Autoimmune Bullous Dermatoses in Northeastern Romania

BACKGROUND

Autoimmune bullous diseases (ABDs) are a rare but significant group of dermatoses that pose great challenges to the treating dermatologist. ABDs are characterized by the presence of tissue-bound and circulating autoantibodies directed against disease-specific target antigens of the skin. Most epidemiological studies have focused on a single ABD. More than that, there are few data about the incidence and prevalence of autoimmune blistering diseases in Romania.

METHODS

In this study, between 2015 and 2019, we retrospectively investigated a total of 225 patients with autoimmune bullous diseases from the northeastern region of Romania. The diagnosis was based on the clinical and histo- and immunohistological findings.

RESULTS

Pemphigus was the most frequently encountered ABD, with an incidence of 8.16/1,000,000 inhabitants, representing 58.7% (132 cases), followed by 24% cases of bullous pemphigoid (54 cases), 15.4% of patients were diagnosed with dermatitis herpetiformis (37 cases), and 0.9% other subepidermal autoimmune bullous dermatoses. The average age of onset of pemphigus vulgaris was 59.4 years, the majority of patients being male, while the average age of patients diagnosed with bullous pemphigoid was 73.8 years, the majority being female.

CONCLUSIONS

Pemphigus vulgaris is the most frequently encountered ABDs in the northeast of Romania, with a higher incidence than in Western European countries, and this may be due to specific peculiarities of the geographical area, as well as to a genetic susceptibility of the population in this region.

A desmosomal cadherin controls multipotent hair follicle stem cell quiescence and orchestrates regeneration through adhesion signaling

Stem cells (SCs) are critical to maintain tissue homeostasis. However, it is currently not known whether signaling through cell junctions protects quiescent epithelial SC reservoirs from depletion during disease-inflicted damage. Using the autoimmune model disease pemphigus vulgaris (PV), this study reveals an unprecedented role for a desmosomal cadherin in governing SC quiescence and regeneration through adhesion signaling in the multipotent mouse hair follicle compartment known as the bulge. Autoantibody-mediated, mechanical uncoupling of desmoglein (Dsg) 3 transadhesion activates quiescent bulge SC which lose their multipotency and stemness, become actively cycling, and finally delaminate from their epithelial niche. This then initiates a self-organized regenerative program which restores Dsg3 function and bulge morphology including SC quiescence and multipotency. These profound changes are triggered by the sole loss of functional Dsg3, resemble major signaling events in Dsg3-/- mice, and are driven by SC-relevant EGFR activation and Wnt modulation requiring longitudinal repression of Hedgehog signaling.

Alterations of fecal microbiome and metabolome in pemphigus patients

The role of gut microbiome and metabolic substances in the development of autoimmune diseases has gradually been revealed. However, the relevant gut features in pemphigus have not been well clarified. We collected stool samples from pemphigus patients and healthy controls (HCs). Metagenomic sequencing and liquid chromatography-mass spectrometry (LC/MS) metabolome sequencing were performed to analyze the compositional and metabolic alternations of the gut microbiome in pemphigus patients and HCs. We observed the reduced richness and diversity and greater heterogeneity in pemphigus patients, which was characterized by a significant decrease in Firmicutes and an increase in Proteobacteria. At the species level, Intestinal pathogenic bacteria such as Escherichia coli and Bacteroides fragilis were significantly enriched, while anti-inflammatory bacteria and butyric acid-producing bacteria were significantly reduced, which were related to clinical indicators (Dsg1/3 and PDAI). 4 species were selected by the machine learning algorithm to better distinguish pemphigus patients from healthy people. Metabolomic analysis showed that the composition of pemphigus patients was different from that of HCs. PE (18:3 (6Z,9Z, 12Z)/14:1 (9Z)) was the main metabolic substance in pemphigus and involved in a variety of metabolic pathways. While Retinol, flavonoid compounds and various amino acids decreased significantly compared with HCs. Furthermore, we found that differences in the levels of these metabolites correlated with changes in the abundance of specific species. Our study provides a comprehensive picture of gut microbiota and metabolites in pemphigus patients and suggests a potential mechanism of the aberrant gut microbiota and metabolites in the pathogenesis of pemphigus.

Diagnostic Techniques in Autoimmune Blistering Diseases

Autoimmune blistering diseases (AIBD) comprise a heterogeneous group of uncommon disorders of the skin and mucous membranes, characterised by antibodies targeting structural proteins within epithelial tissue and the underlying basement membrane. There can be significant overlap in clinical presentation of these diseases and accurate diagnosis relies on the detection and characterisation of relevant autoantibodies. Immunofluorescence provides the gold-standard diagnostic tool for these diseases, identifying both tissue-bound autoantibodies in biopsy material using direct immunofluorescence and circulating antibodies in serum through indirect immunofluorescence. Following advances in the identification and subsequent characterisation of numerous antigenic targets in these diseases, the development of antigen-specific tests, in particular, enzyme-linked immunosorbent assays on serum specimens, has provided a third key tool to not only identify, but also quantify AIBD autoantibodies. This quantification has proven particularly useful in monitoring disease activity and informing clinical management decisions. Accurate diagnosis of these diseases is important since optimal treatment strategies differ between them and, prognostically, some diagnoses are associated with an increased risk of malignancy. This review outlines the molecular pathology underlying the major AIBD and describes how the three principal techniques can be used in combination, to provide best practice for diagnosis and treatment monitoring.

Tacrolimus reverses pemphigus vulgaris serum-induced depletion of desmoglein in HaCaT cells via inhibition of heat shock protein 27 phosphorylation

BACKGROUND

Glucocorticoids are the first-line treatment for Pemphigus vulgaris (PV), but its serious side effects can be life-threatening for PV patients. Tacrolimus (FK506) has been reported to have an adjuvant treatment effect against PV. However, the mechanism underlying the inhibitory effect of FK506 on PV-IgG-induced acantholysis is unclear.

OBJECTIVE

The objective of this study was to explore the effect of FK506 on desmoglein (Dsg) expression and cell adhesion in an immortalized human keratinocyte cell line (HaCaT cells) stimulated with PV sera.

METHODS

A cell culture model of PV was established by stimulating HaCaT cells with 5% PV sera with or without FK506 and clobetasol propionate (CP) treatment. The effects of PV sera on intercellular junctions and protein levels of p38 mitogen-activated protein kinase (p38MAPK), heat shock protein 27 (HSP27), and Dsg were assayed using western blot analysis, immunofluorescence staining, and a keratinocyte dissociation assay.

RESULTS

PV sera-induced downregulation of Dsg3 was observed in HaCaT cells and was blocked by FK506 and/or CP. Immunofluorescence staining revealed that linear deposits of Dsg3 on the surface of HaCaT cells in the PV sera group disappeared and were replaced by granular and agglomerated fluorescent particles on the cell surface; however, this effect was reversed by FK506 and/or CP treatment. Furthermore, cell dissociation assays showed that FK506 alone or in combination with CP increased cell adhesion in HaCaT cells and ameliorated loss of cell adhesion induced by PV sera. Additionally, FK506 noticeably decreased the PV serum-induced phosphorylation of HSP 27, but had no effect on p38MAPK phosphorylation.

CONCLUSION

FK506 reverses PV-IgG induced-Dsg depletion and desmosomal dissociation in HaCaT cells, and this effect may be obtained by inhibiting HSP27 phosphorylation.

Optimal biopsy site for the diagnosis of oral pemphigus vulgaris and mucous membrane pemphigoid: a systematic review and meta-analysis

The aim of this study was to critically evaluate the diagnostic yields of direct immunofluorescence (DIF) analysis on perilesional and normal-appearing mucosa biopsy samples, to determine the optimal biopsy site for patients presenting with oral pemphigus vulgaris (PV) or mucous membrane pemphigoid (MMP). Electronic databases and article bibliographies were searched in December 2022. The primary outcome was the rate of DIF positivity. Of 374 records identified after the elimination of duplicates, 21 studies with 1027 samples were ultimately included. Meta-analysis revealed a pooled DIF positivity rate of 99.6% (95% confidence interval (CI) 97.4-100.0%, I2 = 0%) for PV and 92.6% (95% CI 87.9-96.5%, I2 = 44%) for MMP for biopsies from perilesional sites, and of 95.4% (95% CI 88.6-99.5%, I2 = 0%) for PV and 94.1% (95% CI 86.5-99.2%, I2 = 42%) for MMP for biopsies from normal-appearing sites. For MMP, there was no significant difference in the rate of DIF positivity between the two biopsy sites (odds ratio 1.91, 95% CI 0.91-4.01, I2 = 0%). The results suggest that the perilesional mucosa remains the optimal biopsy site for DIF diagnosis of oral PV, while the normal-appearing mucosa biopsy is optimal for oral MMP.

Combination therapy for management of pemphigus patients with unexpected therapeutic response to rituximab: A report of five cases

Key Clinical Message

The immunosuppressant agents should be considered earlier in the course of treatment with rituximab, possibly after the unfavorable response at first cycle of treatment, especially in male patients and those with high BMI.

Abstract

Rituximab (RTX) has recently been proposed as an alternative first-line therapy for pemphigus patients. However, there are some rare reports of worsening of pemphigus following RTX therapy in the literature. This study aimed to evaluate the efficacy and safety of using a combination treatment of mycophenolate mofetil or dapsone and methotrexate in case of nonresponse, exacerbation or development of allergic reactions following rituximab therapy in pemphigus patients. In this case series, archive files of pemphigus patient in a tertiary care hospital from 2016 to 2021 who were treated with rituximab were reviewed and those with failure in treatment process including nonresponsiveness, exacerbation or development of allergic reactions to rituximab were identified and assessed. The study includes five patients out of 1245 RTX-treated patients, who did not respond to RTX (one patient) or experienced an exacerbation of disease (two patients) or development of allergic reactions (two patients). Male patients with high BMI (BMI > 25) whose response to rituximab was not good at first cycle and happened to receive rituximab later in the course of disease, had highest number of relapses and benefited the most from this combination immunosuppressive treatment as an alternative for repeating rituximab cycles. The lower risk of relapse and a better chance of remission might indicate the efficacy of adjuvant immunosuppressant therapy in patients with no-response, exacerbation, or allergic reaction to rituximab. These therapeutic effects were better observed in patients who received lower doses of rituximab which could suggest that the immunosuppressant agents should be considered earlier in the course of the disease, possibly after the first failed trial of rituximab therapy.

Systemic lupus erythematosus combined with Castleman disease and secondary paraneoplastic pemphigus: a case report

BACKGROUND

The literature describes a case of systemic lupus erythematosus (SLE) complicated with Castleman's disease (CD) and secondary paraneoplastic pemphigus (PNP).

CASE PRESENTATION

A 12-year-old female presented with a neck mass, rash, arthralgia, and skin and mouth ulceration for 5 years were admitted. All blood cells were low. Multiple autoantibodies associated with SLE were positive. The pathology of the neck mass revealed the classical manifestations of CD. She was treated with prednisone, hydroxychloroquine, leflunomide, thalidomide, and dressings. Pathological examination of the skin revealed PNP. The neck mass was removed and continued to take antirheumatic drugs. At subsequent follow-up, the patient's disease status was stable and the skin mucosal lesion did not recur.

CONCLUSION

The case of simultaneous SLE, CD, and PNP in children was rarely reported, and the correct diagnosis of the disease will help to take timely treatment.

Retrospective analysis of autoimmune bullous diseases in Middle Franconia

Introduction

Autoimmune bullous diseases (AIBDs) are a group of rare cutaneous disorders affecting cornified skin and mucous membranes. They are characterized by tense or flaccid blistering and erosions due to autoantibodies against desmosomal and hemidesmosomal structural proteins of the skin. This group of disorders can be divided into those of pemphigoid and those of pemphigus diseases. If left untreated, these autoimmune diseases can cause serious or even life-threatening complications such as loss of fluid, superinfections or impaired food intake. Due to modern standardized serological assays, the diagnosis of AIBDs can usually be confirmed in combination with their clinical appearance. Whereas for a long time corticosteroids were the major players in the treatment of these diseases, with the approval of rituximab and other immunosuppressive agents, the therapy has increasingly improved.

Methods

In this study, we aimed to investigate epidemiologic and clinical features as well as diagnostics and therapy of bullous autoimmune diseases in Middle Franconia, a governorate within the German federal state of Bavaria. Patients diagnosed or treated because of a AIBDs between 01.04.2013 and 31.03.2019 at the dermatological department of the university hospital Erlangen were included in this retrospective study (n = 242). Patients were either diagnosed for the first time (n=176) or the diagnosis has been confirmed (n=66) at the department. The respective incidence was calculated among the 176 subjects who had been diagnosed at the center in this period. Data was taken from patient records and analyzed with Microsoft® Excel. The evaluation included the diagnoses of pemphigus vulgaris (PV), pemphigus foliaceus (PF), bullous pemphigoid (BP), mucous membrane pemphigoid (MMP), linear IgA dermatosis (LAD), epidermolysis bullosa acquisita (EBA), and dermatitis herpetiformis (DH).

Results

This study shows that the incidence of each AIBDs in Middle Franconia is low and comparable (PV, PF, LAD, EBA) or lower (BP, MMP, DH) than in other studies and regions. BP is the most common newly diagnosed AIBD in Middle Franconia.

Discussion

Due to the chronic and sometimes severe course of AIBDs, repeated in-house treatments are often necessary. To date, mainly topically and systemically applied corticosteroids in combination with immunomodulators are used as first-line therapy.

Psychological morbidity in patients with pemphigus and its clinicodemographic risk factor: A comparative study

Due to the long disease duration, impact on appearance, social stigmatization, and numerous side effects of treatment, pemphigus, an autoimmune bullous disease, often has a significant psychological impact on patients. On the other hand, mood disorders may exacerbate the disease by affecting the patient's self-management, forming a vicious circle. To investigate anxiety and depressive disorders in patients with pemphigus, a total of 140 patients with pemphigus were recruited for this cross-sectional retrospective study between March 2020 and January 2022. A control group of 118 patients with psoriasis, a commonly known psychosomatic dermatosis, was established. Patients were evaluated at the visiting day with the Beck Anxiety Inventory and Beck Depression Inventory second edition for mood disorders, the Dermatology Life Quality Index and the EuroQol Five Dimensions Questionnaire for disease-related life quality, and the Visual Analogue Scale for pain and itching symptoms. In our cohort, 30.7% of patients with pemphigus suffered from either anxiety disorder (25%) or depressive disorders (14.3%). Propensity score matching was implemented to create a comparable cohort of pemphigus and psoriasis groups considering the baseline discrepancy. Thirty-four comparable pairs of pemphigus and psoriasis patients were extracted. The prevalence and severity of depressive disorder in pemphigus patients were significantly higher than in psoriasis patients, while anxiety disorder levels appeared to be similar in two groups. Multivariate logistic regression analysis further revealed that disease-related hospitalization history, active mucosal damage, and concomitant thyroid disease are independent risk factors for mood disorders in pemphigus patients. Our results showed that pemphigus patients had a high prevalence and severity of mood disorders. Relevant clinicodemographic indicators may be valuable for prediction and early identification of mood disorders in pemphigus. Better disease education from physicians may be important for these patients to achieve overall disease management.

Evaluation of clinical factors and outcome of systemic glucocorticoid therapy discontinuation in patients with pemphigus achieving complete remission

Therapy discontinuation of systemic glucocorticoid treatment for pemphigus remains uncertain at the clinical end point of complete remission. The objective of this study was to identify the factors associated with achieving complete remission off therapy (CROT) and analyze the occurrence of relapse after therapy discontinuation. A retrospective cohort study was conducted at the Department of Dermatology of Peking University First Hospital. A total of 447 patients with pemphigus treated from 2005 to 2020 were identified. Univariate and multivariate analyses were conducted to analyze the associated factors of CROT and to evaluate the outcomes. The mean age was 48 years (±13.4 years), and 54.6% of the patients were women. During a median follow-up of 59 months (43-87.5 months), 160 of 447 (35.8%) patients achieved CROT after a median treatment duration of 51 months (38-66.2 months). Patients with a shorter therapy duration to complete remission on minimal therapy and negative desmoglein antibodies tested in remission were more likely to achieve early CROT. Thirty-five of 160 (21.9%) patients experienced relapse after CROT. Patients who discontinued therapy without guidance experienced significantly faster and higher occurrences of relapse than those withdrawing under guidance (log-rank p = 0.01). Minimal therapy maintenance ≤8 months from complete remission on minimal therapy and positive desmoglein antibodies tested at withdrawal increased the risk of early relapse after CROT.

Immune cells in pemphigus vulgaris and bullous Pemphigoid: From pathogenic roles to targeting therapies

Pemphigus vulgaris (PV) and bullous pemphigoid (BP) are two major subtypes of autoimmune bullous diseases (AIBD), characterized by blisters and erosions of skin and/or mucous membranes with dysregulated immune activity. Current literature established that T and B cells are the main executors of PV and BP. Emerging evidence revealed that macrophages and related cytokines also contribute to these diseases. While the role of lymphocytes on PV and BP is well established, the definitive functions of macrophages in disease progression are not fully understood. Furthermore, current status of clinical trials targeting immune cells is poorly recapitulated in PV and BP. In this review, we summarized current knowledge in this rapidly advancing field, with emphasis on the individual functions of immune cells and their interactions, as well as ongoing clinical trials targeting immune cells, to provide novel insights in mechanistic understanding and clinical management of PV and BP.

Precision in treatment evaluation: importance of minimal clinically important differences (MCIDs) of outcome measures for autoimmune blistering diseases

Autoimmune blistering diseases (AIBDs) comprise a group of rare conditions marked by autoantibodies that specifically target intercellular adhesion molecules. Despite the progress made in comprehending the disease and the increasing number of treatment options available, there is still no definitive cure for AIBDs such as pemphigus, and it continues to have a devastating impact on those affected. The challenges in achieving new approved therapies for AIBDs are complex and multifaceted. One significant obstacle was the prior lack of validated and standardized outcome measures, which are crucial for ensuring precise comparisons between new and traditional therapies. This gap in knowledge has prompted the development of minimal clinically important differences (MCIDs), which enable efficient and reliable comparison of therapeutic outcomes between trials. MCID is defined as the minimum difference in an outcome measure that indicates a clinically significant improvement/deterioration in disease severity. Additionally, MCIDs provide a patient-centered approach to evaluating treatment efficacy, by considering whether patients experience a subjective improvement in their symptoms. Therefore, this literature review will examine the derivation and significance of MCIDs for various scoring systems in AIBDs.

Cicatricial alopecia associated with pemphigus

Pemphigus is a chronic autoimmune bullous disease associated with the production of autoantibodies directed against desmosomal proteins, such as desmogleins 1 and 3. Here, we present the case of an 83-year-old woman who was referred to us with suspicious cicatricial alopecia of the scalp and a small, eroded lesion on the forehead, previously labeled as atrophic actinic keratosis after a skin biopsy. In our clinic, after a careful examination of the case, we decided to perform two new skin biopsies of the scalp on suspicion of an inflammatory disease.

The Impact of the Initial Phase of the COVID-19 Pandemic on Patients With Autoimmune Bullous Diseases

Introduction The follow-up of patients with autoimmune bullous diseases (AIBDs) was temporarily interrupted during the initial phase of the COVID-19 pandemic due to restrictions in healthcare services, given the high contagiousness and rapid spread of SARS-CoV-2. Our objective was to assess the impact of the initial phase of the COVID-19 pandemic on the treatments and disease activity of AIBD patients. Methods We conducted a telephone survey of patients with AIBDs who had been regularly followed up in our hospital prior to the onset of the pandemic. A structured questionnaire that we designed was used. This questionnaire comprised questions examining the following issues between March and June of 2020: patients' follow-up, treatment, COVID-19 infection status, and changes in disease activity. Results Thirty-nine patients were included in the study. Among those, 26 (66.7%) were immunosuppressed. The frequency of follow-up for 37 patients (94.9%) changed significantly (p<0.001): 28 patients (71.8%) did not visit the hospital, and 26 of them (92.9%) did not communicate at all. The treatment for 10 patients (25.6%) was altered, either by their physician or by themselves. Disease activity reactivated in patients who altered their own treatments. There was only one patient (2.6%) who contracted COVID-19. Conclusions Documenting this period revealed that some patients were negatively impacted by the pandemic initially. The most significant contributing factor was the interruption of patient-physician communication.

The human skin organ culture model as an optimal complementary tool for murine pemphigus models

Pemphigus is a severe autoimmune bullous disease of the skin and/or mucous membranes caused by autoantibodies that mainly target the adhesion proteins desmoglein (Dsg) 3 and/or Dsg1. Clinically, pemphigus is characterized by flaccid blistering, leading to severe water and electrolyte loss. Before the introduction of corticosteroid treatment, the disease turned out to be fatal in many cases. Despite recent therapeutic improvements, treatment of pemphigus patients is centred on prolonged systemic immunosuppression and remains challenging. Current drug development for pemphigus has a strong focus on disease-causing B cells and autoantibodies and, more recently, also on modulating autoantibody-induced tissue pathology and keratinocyte signalling. This drug development requires reliable pre-clinical model systems replicating the pathogenesis of the human disease. Among those are neonatal and adult mouse models based on the transfer of Dsg3, Dsg1/3 or Dsg1-specific autoantibodies. To reduce the number of animal experiments, we recently established a standardized human skin organ culture (HSOC) model for pemphigus. This model reproduces the clinical phenotype of autoantibody-induced tissue pathology in pemphigus vulgaris. For induction of blistering, a recombinant single-chain variable fragment (scFv) targeting both Dsg1 and 3 is injected into pieces of human skin (obtained from plastic surgeries). Further characterization of the HSOC model demonstrated that key morphologic, molecular and immunologic features of pemphigus are being replicated. Thus, the pemphigus HSOC model is an excellent alternative to pemphigus animal model systems that are based on the transfer of (auto)antibodies.

cAMP: A master regulator of cadherin-mediated binding in endothelium, epithelium and myocardium

Regulation of cadherin-mediated cell adhesion is crucial not only for maintaining tissue integrity and barrier function in the endothelium and epithelium but also for electromechanical coupling within the myocardium. Therefore, loss of cadherin-mediated adhesion causes various disorders, including vascular inflammation and desmosome-related diseases such as the autoimmune blistering skin dermatosis pemphigus and arrhythmogenic cardiomyopathy. Mechanisms regulating cadherin-mediated binding contribute to the pathogenesis of diseases and may also be used as therapeutic targets. Over the last 30 years, cyclic adenosine 3',5'-monophosphate (cAMP) has emerged as one of the master regulators of cell adhesion in endothelium and, more recently, also in epithelial cells as well as in cardiomyocytes. A broad spectrum of experimental models from vascular physiology and cell biology applied by different generations of researchers provided evidence that not only cadherins of endothelial adherens junctions (AJ) but also desmosomal contacts in keratinocytes and the cardiomyocyte intercalated discs are central targets in this scenario. The molecular mechanisms involve protein kinase A- and exchange protein directly activated by cAMP-mediated regulation of Rho family GTPases and S665 phosphorylation of the AJ and desmosome adaptor protein plakoglobin. In line with this, phosphodiesterase 4 inhibitors such as apremilast have been proposed as a therapeutic strategy to stabilize cadherin-mediated adhesion in pemphigus and may also be effective to treat other disorders where cadherin-mediated binding is compromised.

Targeting Th17 cells: a promising strategy to treat oral mucosal inflammatory diseases

With the improved quality of life, oral health is under increased pressure. Numerous common oral mucosal diseases, such as oral lichen planus(OLP) and gingivitis, are related to the destruction of the oral immune barrier. The cytokines secreted by T-helper 17 (Th17) cells are essential for maintaining oral immune homeostasis and play essential roles in immune surveillance. When antigens stimulate the epithelium, Th17 cells expand, differentiate, and generate inflammatory factors to recruit other lymphocytes, such as neutrophils, to clear the infection, which helps to maintain the integrity of the epithelial barrier. In contrast, excessive Th17/IL-17 axis reactions may cause autoimmune damage. Therefore, an in-depth understanding of the role of Th17 cells in oral mucosa may provide prospects for treating oral mucosal diseases. We reviewed the role of Th17 cells in various oral and skin mucosal systemic diseases with oral characteristics, and based on the findings of these reports, we emphasize that Th17 cellular response may be a critical factor in inflammatory diseases of the oral mucosa. In addition, we should pay attention to the role and relationship of "pathogenic Th17" and "non-pathogenic Th17" in oral mucosal diseases. We hope to provide a reference for Th17 cells as a potential therapeutic target for treating oral mucosal inflammatory disorders in the future.

Catalytic antibodies in arrhythmogenic cardiomyopathy patients cleave desmoglein 2 and N-cadherin and impair cardiomyocyte cohesion

AIMS

Arrhythmogenic cardiomyopathy (AC) is a severe heart disease predisposing to ventricular arrhythmias and sudden cardiac death caused by mutations affecting intercalated disc (ICD) proteins and aggravated by physical exercise. Recently, autoantibodies targeting ICD proteins, including the desmosomal cadherin desmoglein 2 (DSG2), were reported in AC patients and were considered relevant for disease development and progression, particularly in patients without underlying pathogenic mutations. However, it is unclear at present whether these autoantibodies are pathogenic and by which mechanisms show specificity for DSG2 and thus can be used as a diagnostic tool.

METHODS AND RESULTS

IgG fractions were purified from 15 AC patients and 4 healthy controls. Immunostainings dissociation assays, atomic force microscopy (AFM), Western blot analysis and Triton X-100 assays were performed utilizing human heart left ventricle tissue, HL-1 cells and murine cardiac slices. Immunostainings revealed that autoantibodies against ICD proteins are prevalent in AC and most autoantibody fractions have catalytic properties and cleave the ICD adhesion molecules DSG2 and N-cadherin, thereby reducing cadherin interactions as revealed by AFM. Furthermore, most of the AC-IgG fractions causing loss of cardiomyocyte cohesion activated p38MAPK, which is known to contribute to a loss of desmosomal adhesion in different cell types, including cardiomyocytes. In addition, p38MAPK inhibition rescued the loss of cardiomyocyte cohesion induced by AC-IgGs.

CONCLUSION

Our study demonstrates that catalytic autoantibodies play a pathogenic role by cleaving ICD cadherins and thereby reducing cardiomyocyte cohesion by a mechanism involving p38MAPK activation. Finally, we conclude that DSG2 cleavage by autoantibodies could be used as a diagnostic tool for AC.

Ocular involvement in autoimmune bullous diseases

Autoimmune bullous diseases represent a heterogenous group of disorders caused by autoantibodies against adhesion molecules; the location of the target protein determines the level of cleft formation. The spectrum of ocular lesions in autoimmune bullous diseases can range from mild symptoms to severe involvement with sight impairment and even, in some cases, blindness. In pemphigus vulgaris, the prevalence of ocular involvement has been reported to be between 7% and 26%. The most common clinical sign of ocular pemphigus vulgaris is bilateral conjunctivitis with hyperemia. Ocular involvement also occurs in 41% to 70% of patients with paraneoplastic pemphigus. The main ocular manifestations are bilateral cicatrizing conjunctivitis with symblepharon formation, and shortening of the fornices. In mucous membrane pemphigoid, ocular involvement is seen in 61% to 70% of patients; the most frequent ocular finding is cicatricial conjunctivitis. Patients with autoimmune bullous diseases having common ocular involvement should be assessed by an ophthalmologist to avoid serious complications. Diagnostic procedures and treatment require multidisciplinary care based on the close cooperation between dermatologists and ophthalmologists.

The therapeutic age of the neonatal Fc receptor

IgGs are essential soluble components of the adaptive immune response that evolved to protect the body from infection. Compared with other immunoglobulins, the role of IgGs is distinguished and enhanced by their high circulating levels, long half-life and ability to transfer from mother to offspring, properties that are conferred by interactions with neonatal Fc receptor (FcRn). FcRn binds to the Fc portion of IgGs in a pH-dependent manner and protects them from intracellular degradation. It also allows their transport across polarized cells that separate tissue compartments, such as the endothelium and epithelium. Further, it is becoming apparent that FcRn functions to potentiate cellular immune responses when IgGs, bound to their antigens, form IgG immune complexes. Besides the protective role of IgG, IgG autoantibodies are associated with numerous pathological conditions. As such, FcRn blockade is a novel and effective strategy to reduce circulating levels of pathogenic IgG autoantibodies and curtail IgG-mediated diseases, with several FcRn-blocking strategies on the path to therapeutic use. Here, we describe the current state of knowledge of FcRn-IgG immunobiology, with an emphasis on the functional and pathological aspects, and an overview of FcRn-targeted therapy development.

Autoimmune blistering diseases: promising agents in clinical trials

INTRODUCTION

Treatment options for autoimmune bullous diseases (AIBD) are currently limited to corticosteroids and traditional immunomodulants and immunosuppressants that are associated with unfavorable adverse effect profiles. The most frequent AIBDs, i.e. bullous pemphigoid, pemphigus vulgaris, and mucous membrane pemphigoid, impose a high disease burden onto affected patients and can be detrimental due to infections, exsiccosis, and impaired food intake. Significant progress has been made in elucidating disease mechanisms and key mediators by in vivo and in vitro models, thus identifying a multifaceted range of possible drug targets. However, except for rituximab for pemphigus vulgaris, no new drugs have been approved for the treatment of AIBDs in the last decades.

AREAS COVERED

This review covers new drug developments and includes ongoing or completed phase 2 and 3 clinical trials. Studies were identified by querying the registries of ClinicalTrials.gov and Cochrane Library.

EXPERT OPINION

Promising results were shown for a variety of new agents including nomacopan, efgartigimod, omalizumab, dupilumab, as well as chimeric autoantibody receptor T cells. Clinical translation in the field of AIBDs is highly active, and we anticipate significant advances in the treatment landscape.

Janus kinase inhibitor-Tofacitinib associated with pemphigus: an analysis of the FDA adverse event reporting system data

OBJECTIVES

To establish the association between the therapy of Janus kinase inhibitors and the adverse event of pemphigus in patients with rheumatologic and inflammatory disorders.

METHODS

A disproportionality analysis using multi-item gamma Poisson shrinker was conducted to identify signals between medication and adverse events within the FDA Adverse Event Reporting System.

RESULTS

The spontaneous reporting system contained 3,032 pemphigus reports associated with two Janus kinase inhibitors, namely Tofacitinib and Upadacitinib. The year/reporter/geographic area/country/age/sex/indication with the highest number of cases were the year of 2021, physician, North America, Canada, age between 40-49, female and rheumatoid arthritis, respectively. A significant signal was detected in the Tofacitinib group.

CONCLUSION

Pemphigus, a rare and potentially fatal adverse event, was found to occur more frequently in patients receiving Tofacitinib. High-risk individuals were identified as female, age between 40-49, or with rheumatoid arthritis. Medication, adverse events, and underlying disease conditions were identified as potential contributing factors. Rheumatology and dermatology specialists should exercise increased vigilance in clinical practice.