A case of IgA pemphigus with acantholysis in oral mucosal lesions

IgA pemphigus is an autoimmune bullous disease caused by anti-keratinocyte cell surface IgA autoantibodies. Mucous membrane involvement is rare in IgA pemphigus. We report a case of IgA pemphigus with oral mucosal lesions, in which acantholysis was pathologically confirmed. A 31-year-old woman presented with skin erythema with small pustules and oral mucosal erosions. Histopathological examination of the erosions on her oral mucosa and papules on her back revealed acantholysis and intraepidermal infiltration of neutrophils. Direct immunofluorescence tests showed intercellular deposition of IgA, but not IgG, mainly in the lower, but not entire, layer of the epidermis. C3 was linearly present in the basement membrane zone (BMZ), but not in the intercellular space. Enzyme-linked immunosorbent assay revealed that both anti-desmoglein (Dsg) 3 IgA and IgG were positive. Neither IgA nor IgG against desmocollin 1-3 were detected. This case was clinically and histologically compatible with IgA pemphigus, but immunologically anti-BMZ autoimmunity was additionally observed. IgA pemphigus is classified into two major types: subcorneal pustular dermatosis type and intraepidermal neutrophilic dermatosis type. This case was not typical in terms of rarely observed oral lesions and predominant deposition of IgA in the lower layer of the epidermis. Instead, this case could be considered a rare subtype of IgA pemphigus, IgA-pemphigus vulgaris. Oral lesions in IgA pemphigus may be clinical clue of having anti-Dsg3 IgA that cannot be routinely examined.

Comprehensive analysis of long COVID in a Japanese nationwide prospective cohort study

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly since 2019, and the number of reports regarding long COVID has increased. Although the distribution of long COVID depends on patient characteristics, epidemiological data on Japanese patients are limited. Hence, this study aimed to investigate the distribution of long COVID in Japanese patients. This study is the first nationwide Japanese prospective cohort study on long COVID.

METHODS

This multicenter, prospective cohort study enrolled hospitalized COVID-19 patients aged ≥18 years at 26 Japanese medical institutions. In total, 1200 patients were enrolled. Clinical information and patient-reported outcomes were collected from medical records, paper questionnaires, and smartphone applications.

RESULTS

We collected data from 1066 cases with both medical records and patient-reported outcomes. The proportion of patients with at least one symptom decreased chronologically from 93.9% (947/1009) during hospitalization to 46.3% (433/935), 40.5% (350/865), and 33.0% (239/724) at 3, 6, and 12 months, respectively. Patients with at least one long COVID symptom showed lower quality of life and scored higher on assessments for depression, anxiety, and fear of COVID-19. Female sex, middle age (41-64 years), oxygen requirement, and critical condition during hospitalization were risk factors for long COVID.

CONCLUSIONS

This study elucidated the symptom distribution and risks of long COVID in the Japanese population. This study provides reference data for future studies of long COVID in Japan.

Solid state 1H, 7Li, and 13C NMR studies on new ionic plastic crystals of crown ether-Li-TFSA complexes

This study provides the first evidence that a Li ion can form ionic plastic crystals using crown ether with a bis-(trifluoromethanesulphonyl) amide (TFSA) anion. 1H, 7Li, and 13C nuclear-magnetic-resonance (NMR) measurements of the 15-crown-5-Li-TFSA complex revealed that the constituents underwent isotropic reorientation in the plastic crystalline phase. The NMR data of the 12-crown-4-Li-TFSA salt showed that the complex is a rotator crystal (the complexes are denoted as [Li 15C5] and [Li 12C4] in this paper). The X-ray diffraction (XRD) reflection patterns of the [Li 15C5] crystal recorded in the highest-temperature solid phase (plastic phase) could be indexed to a cubic structure. Conversely, [Li 12C4] could be fitted to a trigonal structure. In this study, [M (3n)Cn] (M = Li, Na, K; n = 4-6) complexes were also prepared, and NMR, DSC, XRD, and electrical conductivity measurements were performed. Based on these results, we additionally revealed that the [Na 15C5] and [K (15C5)2] complexes are also new rotator crystals. Single-crystal XRD measurements also revealed that the [Na 15C5] compound has two stable sites in the crystal. Activation energies of molecular motions in the [M (3n)Cn] crystals were estimated using 1H NMR relaxation time (T1 and T2) measurements. The electrical conductivity measurements of [Li 12C4], [Li 15C5], and [Na 15C5] showed high ionic conductivities (∼10-2 S cm-1).

Desmoglein-Specific B-Cell-Targeted Single-Cell Analysis Revealing Unique Gene Regulation in Patients with Pemphigus

Autoreactive B cells are assumed to play a critical role in pemphigus; however, the characteristics of these cells are not yet fully understood. In this study, 23 pemphigus vulgaris or pemphigus foliaceus samples were used to isolate circulating desmoglein (DSG)-specific B cells. Transcriptome analysis of the samples was performed at the single-cell level to detect genes involved in disease activity. DSG1- or DSG3-specific B cells from three patients' differentially expressed genes related to T cell costimulation (CD137L) as well as B-cell differentiation (CD9, BATF, TIMP1) and inflammation (S100A8, S100A9, CCR3), compared with nonspecific B cells from the same patients. When the DSG1-specific B cells before and after treatment transcriptomes of the patient with pemphigus foliaceus were compared, there were changes in several B-cell activation pathways not detected in non-DSG1-specific B cells. This study clarifies the transcriptomic profile of autoreactive B cells in patients with pemphigus and documents the gene expression related to disease activity. Our approach can be applied to other autoimmune diseases and has the potential for future detection of disease-specific autoimmune cells.

B-cell targeted therapy of pemphigus

Pemphigus is an autoimmune disease that causes blistering and erosion of the skin and mucous membranes because of autoantibodies against desmoglein, which plays an important role in adhesion between epidermal keratinocytes. Treatment of pemphigus has long been centered on corticosteroids, and the guidelines for management of pemphigus have recommended high-dose systemic corticosteroids as the first-line treatment. While guideline-based treatment has been shown to be beneficial in patients with pemphigus, it has also become clear that this treatment is accompanied by significant burden and risk. The challenge for future pemphigus treatment is to maximize efficacy while minimizing risk during the course of the disease. In this regard, treatment targeting B cells is expected to become increasingly important as autoreactive B cells in pemphigus patients are thought to play a major role in the production of autoantibodies, which form the basis of the pathogenesis. The recent expansion of insurance coverage to rituximab, a monoclonal antibody against CD20, for refractory pemphigus in the USA, Europe, and Japan has opened up a new era of pemphigus treatment by enabling treatment strategies with drugs targeting B cells in patients. Here, we discuss the current status and future prospects of pemphigus treatment, focusing on rituximab and Bruton's tyrosine kinase inhibitors, which are expected to become essential drugs for pemphigus treatment in the future.

Rituximab therapy for intractable pemphigus: A multicenter, open-label, single-arm, prospective study of 20 Japanese patients

This was a multicenter clinical trial of rituximab, a chimeric monoclonal IgG antibody directed against CD20, for the treatment of refractory pemphigus vulgaris and pemphigus foliaceus. In total, 20 patients were treated with two doses of rituximab (1000 mg; 2 weeks apart) on days 0 and 14. The primary end point was the proportion of patients who achieved complete or partial remission on day 168 following the first rituximab dose. Of the 20 enrolled patients, 11 (55%) and four (20%) achieved complete and partial remission, respectively; therefore, remission was achieved in a total of 15 patients (75.0% [95% confidence interval, 50.9%-91.3%]). It was demonstrated that the remission rate was greater than the prespecified threshold (5%). In addition, a significant improvement in clinical score (Pemphigus Disease Area Index) and decrease in serum anti-desmoglein antibody level were observed over time. Four serious adverse events (heart failure, pneumonia, radial fracture, and osteonecrosis) were recorded in two patients, of which only pneumonia was considered causally related with rituximab. The level of peripheral blood CD19-positive B lymphocytes was decreased on day 28 after rituximab treatment and remained low throughout the study period until day 168. Our results confirm the efficacy and safety of rituximab therapy for refractory pemphigus in Japanese patients.

Clinical severity scores as a guide for prediction of initial treatment responses in pemphigus and pemphigoid patients

Pemphigus and pemphigoid are autoimmune blistering diseases that affect mucosa and skin. Several clinical scoring systems, including the pemphigus disease area index (PDAI) and the bullous pemphigoid disease area index (BPDAI), have been validated for managing disease activity and severity. Current guidelines recommend that treatment response be evaluated with clinical scores and that additional second-line therapies be considered if initial treatment is insufficient for disease control. However, there have been few studies analyzing correlations between PDAI/BPDAI transitions and initial treatment effects. To investigate whether PDAI/BPDAI transitions during the treatment initiation phase correlate with initial treatment responses and whether such information can be used as a guide for necessary additional treatment, we retrospectively analyzed 67 pemphigus patients and 47 pemphigoid patients who received initial treatment at Keio University between 2012 and 2018. The clinical symptoms were evaluated weekly with PDAI/BPDAI. The patients were divided into two groups: in group A, disease was controlled only with oral corticosteroids and immunosuppressants (initial treatment), whereas in group B additional therapies were required due to insufficient responses. In pemphigus, the PDAI ratio of day 7/day 0 was significantly reduced in group A compared to group B (0.548 vs 0.761, P < 0.01) after initial treatment had started. In pemphigoid, the ratios of day 7/day 0 of BPDAI (erosion/blister) and BPDAI (urticaria/erythema) significantly decreased in group A compared to group B (0.565 vs 0.901 and 0.350 vs 0.760, respectively, P < 0.05). Receiver operating characteristic analyses on PDAI, BPDAI (erosion/blister) and BPDAI (urticaria/erythema) revealed that the cut-off values in the ratios of day 7/day 0 were 0.762, 0.675, and 0.568, respectively. Our results suggest that PDAI/BPDAI transitions during the initial phase of the treatments may be useful to predict the outcome of the treatment provided and the necessity of additional therapies to achieve disease control.

IgM to IgG Class Switching Is a Necessary Step for Pemphigus Phenotype Induction in Desmoglein 3-Specific B Cell Receptor Knock-in Mouse

Pemphigus vulgaris is an autoimmune blistering disease caused by IgG targeting desmoglein 3 (Dsg3), an adhesion molecule of keratinocytes. Anti-Dsg3 IgG production is prevented in healthy individuals, but it is unclear how Dsg3-specific B cells are regulated. To clarify the immunological condition regulating Dsg3-specific B cells, a pathogenic anti-Dsg3 Ig (AK23) knock-in mouse was generated. AK23 knock-in B cells developed normally without undergoing deletion or acquiring an anergic phenotype in vivo. The knock-in B cells showed Ca²⁺ influx upon IgM cross-linking and differentiated into AK23-IgG⁺ B cells after LPS and IL-4 stimulation in vitro that induced a pemphigus phenotype after adoptive transfer into Rag2 ^-/- mice. However, the knock-in mouse itself produced AK23-IgM but little IgG without blisters in vivo. Dsg3 immunization and skin inflammation caused AK23-IgG production and a pemphigus phenotype in vivo. Furthermore, Fcgr2b deficiency or haploinsufficiency spontaneously induced AK23-IgG production and a pemphigus phenotype with poor survival rates in AK23 knock-in mice. To assess Fcgr2b involvement in Ig class-switch efficiency, postswitch transcripts of B cells were quantified and significantly higher in Fcgr2b ^-/- and Fcgr2b ^+/- mice than wild-type mice in a gene dose-dependent manner. Finally, RNA sequencing revealed reduced expression of FCGR2B and FcγRIIB-related genes in patient B cells. These results indicated that Dsg3-specific B cells do not spontaneously perform pathogenic class switching in vivo, and pemphigus phenotype induction was prevented under normal conditions. Attenuated FcγRIIB signaling is also one of the drivers for pathogenic class switching and is consistent with immunological features identified from clinical samples. This study unveiled a characteristic immune state silencing autoreactive B cells in mice.

The pathogeneses of pemphigus and pemphigoid diseases

Autoimmune bullous diseases (AIBDs) are skin disorders which are mainly induced by autoantibodies against desmosomal or hemidesmosomal structural proteins. Previous studies using patients' samples and animal disease models identified target antigens and elucidated the mechanisms of blister formation. Pemphigus has been the subject of more active clinical and basic research than any other AIBD. These efforts have revealed the pathogenesis of pemphigus, which in turn has led to optimal diagnostic methods and novel therapies, such as rituximab. In bullous pemphigoid (BP), studies with passive-transfer mouse models using rabbit anti-mouse BP180 antibodies and studies with passive-transfer or active mouse models using autoantigen-humanized mice elucidated the immune reactions to BP180 in vivo. Recently, dipeptidyl peptidase-4 inhibitors have attracted attention as a trigger for BP. For epidermolysis bullosa acquisita (EBA), investigations using mouse models are actively under way and several molecules have been identified as targets for novel therapies. In this review, we give an overview and discussion of the recent progress in our understanding of the pathogenesis of pemphigus, BP, and EBA. Further studies on the breakdown of self-tolerance and on the identification of key molecules that are relevant to blister formation may expand our understanding of the etiology of AIBDs and lead to the development of novel therapeutic strategies.

Comprehensive and long-term surveys of COVID-19 sequelae in Japan, an ambidirectional multicentre cohort study: study protocol

INTRODUCTION

The rapid spread of COVID-19 posed a global burden. Substantial number of people died of the disease in the acute phase of infection. In addition, a significant proportion of patients have been reported to suffer from post-acute phase symptoms, sequelae of COVID-19, which may negatively influence the quality of daily living and/or socioeconomic circumstances of the patients. However, no previous study has comprehensively and objectively assessed the quality of life of patients by using existing international scales. Further, evidence of socioeconomic consequences among patients with COVID-19 is scarce. To address the multidimensional issues from sequelae of COVID-19, evidence from comprehensive surveys beyond clinical perspectives is critical that investigates health, and social determinants of disease progression as well as socioeconomic consequences at a large scale.

METHODS AND ANALYSIS

In this study, we plan to conduct a nationwide and comprehensive survey for the sequelae of COVID-19 in a total of 1000 patients diagnosed at 27 hospitals throughout Japan. This study will evaluate not only the health-related status of patients from clinical perspectives but also the Health-related Quality of Life (HRQoL) scores, socioeconomic status and consequences to discuss the sequelae of the disease and the related risk factors. The primary endpoint is the frequency of long-term complications of COVID-19 infection. The secondary endpoints are risk factors for progression to sequelae of COVID-19 infection. The study will provide robust and important evidence as a resource to tackle the issues from the sequelae of COVID-19 from the multi-dimensional perspectives.

ETHICS AND DISSEMINATION

This trial was approved by the Keio University School of Medicine Ethics Committee (20200243, UMIN000042299). The results of this study will be reported at a society meeting or published in a peer-reviewed journal.

Intravenous Ig Regulates Anti-Desmoglein 3 IgG Production in B220- Antibody-Producing Cells in Mice with Pemphigus Vulgaris

Intravenous Ig (IVIG) is a treatment option for intractable cases of pemphigus vulgaris (PV), an autoimmune blistering disease caused by autoantibodies against desmoglein 3 (DSG3). To investigate the efficacy of IVIG on autoantibody secretion, we produced PV model mice by adoptive transfer of immunized Dsg3^-/- splenocytes to Rag2^-/- mice. We found that circulating anti-DSG3 IgG ELISA titer decreased in PV model mice after 5 days of treatment with IVIG compared with PBS-treated mice, whereas the F(ab')₂ fragment did not suppress the anti-DSG3 IgG titer. enzyme-linked immunospot assay revealed that IVIG treatment reduced the frequency of anti-DSG3 antibody-secreting cells in the spleen but not in lymph nodes and bone marrow. Moreover, this reduction was observed only in the splenic B220^- fraction but not in the B220⁺ fraction. Furthermore, IVIG decreased the serum levels of anti-DSG3 IgG, even after a significant reduction of its titer, owing to antibody-mediated CD20⁺ B cell depletion. In addition, IVIG suppressed anti-DSG3 IgG production in B220^-CD138⁺ plasma cells derived from PV model mice ex vivo. These results indicate that IVIG reduced autoantibody production in B220^- cells containing plasma cells in PV model mice, and this function may indicate one of the mechanisms of action of IVIG on PV.

Analysis of clinical characteristics, prognosis and antibody pathogenicity of pemphigus patients positive for anti-desmoglein IgG autoantibodies in remission: a retrospective cohort study

BACKGROUND

The detection of serum anti-desmoglein (Dsg) IgG autoantibodies has been reported to be useful for assessment of disease activity in pemphigus. However, previous studies have reported that anti-Dsg autoantibodies remain detectable in some patients without active pemphigus lesions.

OBJECTIVES

To investigate the clinical characteristics and antibody pathogenicity of pemphigus patients positive for anti-Dsg IgG autoantibodies in remission.

METHODS

We retrospectively investigated pemphigus patients with a history of clinical remission who visited the Department of Dermatology of Keio University during 2019 and 2020. The antibody pathogenicity was assessed by bead aggregation assay.

RESULTS

When patients were recognized as having entered remission (PDAI = 0 and PSL ≦ 10 mg/day for 2 months), serum autoantibodies against Dsg were detected in 72 of 132 patients (54.5%, positive group; PG), but were not detected in 60 patients (45.5%, negative group; NG). Anti-Dsg antibody titres in remission declined from the active phase in 33 patients in the PG for whom data were available. There were no differences in the chance of reducing PSL to 5 mg/day (P = 0.885) and rate of relapse (P = 0.279) between PG and NG, but fewer patients in PG discontinued corticosteroids (P = 0.004). The ability of patients' sera to block aggregation of Dsg/desmocollin beads was significantly reduced in remission compared to the active phase. However, our results revealed that whole sera in remission still had pathogenic activity in seven of nine patients, and the approximately equal amounts of anti-Dsg antibodies in active phase and remission showed similar pathogenicity.

CONCLUSIONS

This study will provide guidance in cases where autoantibodies are found to be positive in pemphigus patients during remission or steroid reduction.

Cholesterol 25-hydroxylase is a metabolic switch to constrain T cell-mediated inflammation in the skin

Interleukin-27 (IL-27) is an immunoregulatory cytokine whose essential function is to limit immune responses. We found that the gene encoding cholesterol 25-hydroxylase (Ch25h) was induced in CD4⁺ T cells by IL-27, enhanced by transforming growth factor–β (TGF-β), and antagonized by T-bet. Ch25h catalyzes cholesterol to generate 25-hydroxycholesterol (25OHC), which was subsequently released to the cellular milieu, functioning as a modulator of T cell response. Extracellular 25OHC suppressed cholesterol biosynthesis in T cells, inhibited cell growth, and induced nutrient deprivation cell death without releasing high-mobility group box 1 (HMGB1). This growth inhibitory effect was specific to actively proliferating cells with high cholesterol demand and was reversed when extracellular cholesterol was replenished. Ch25h-expressing CD4⁺ T cells that received IL-27 and TGF-β signals became refractory to 25OHC-mediated growth inhibition in vitro. Nonetheless, IL-27–treated T cells negatively affected viability of bystander cells in a paracrine manner, but only if the bystander cells were in the early phases of activation. In mouse models of skin inflammation due to autoreactive T cells or chemically induced hypersensitivity, genetic deletion of Ch25h or Il27ra led to worse outcomes. Thus, Ch25h is an immunoregulatory metabolic switch induced by IL-27 and dampens excess bystander T effector expansion in tissues through its metabolite derivative, 25OHC. This study reveals regulation of cholesterol metabolism as a modality for controlling tissue inflammation and thus represents a mechanism underlying T cell immunoregulatory functions.

Neonatal Linear IgA Bullous Dermatosis Mediated by Breast Milk-Borne Maternal IgA

Importance

Neonatal linear immunoglobulin A (IgA) bullous dermatosis (LABD) is a rare disease that can be fatal when associated with respiratory failure. All previously reported cases of neonatal LABD have been in newborns with healthy asymptomatic mothers, and the pathogenic IgA was of unknown origin.

Objective

To clarify the origin of IgA associated with LABD in neonates born of healthy asymptomatic mothers.

Design, Setting, and Participants

This case study analyzed the laboratory findings of a single breast-fed newborn male with neonatal LABD admitted to the Keio University Hospital in Tokyo and his healthy asymptomatic mother. The healthy newborn developed life-threatening blisters and erosions of the skin and mucous membranes on day 4 after birth. Blood serum, skin, and maternal breast milk were examined for IgA autoantibodies.

Main Outcomes and Measures

Histopathologic and immunofluorescence analyses of specimens (serum, skin, and breast milk) from the patient and his mother.

Results

Histopathologic evaluation of the newborn's skin revealed subepidermal blisters with neutrophil infiltrates, and immunofluorescence testing showed linear IgA deposition along the basement membrane zone (BMZ), which lead to the diagnosis of neonatal LABD. Indirect immunofluorescence using normal human skin after treatment with 1-mol/L sodium chloride showed the patient to have circulating IgA binding to the dermal side of BMZ. Immunohistochemical staining proved the deposition of secretory IgA in the neonatal skin by demonstrating the presence of J chain-not been seen in other LABD cases-indicating that the autoantibodies producing the blisters were derived from the maternal breast milk. Although no circulating IgA against the skin was detected in mother's sera, the breast milk contained IgA that reacted with the dermal side of the BMZ. No new blister formation was observed after cessation of breastfeeding.

Conclusions and Relevance

The results of this case study suggest a passive transfer of pathogenic IgA to a newborn from an asymptomatic mother via breast milk. In prior reports, no serum from asymptomatic mothers of newborns with LABD had IgA autoantibodies binding to skin components; however, in this case, we found that the maternal breast milk contained IgA autoantibodies associated with neonatal LABD. In neonatal LABD, maternal breast milk should be examined for IgA autoantibodies and breast milk feeding should be discontinued as soon as neonatal LABD is suspected.

A multicenter, open-label, uncontrolled, single-arm phase 2 study of tirabrutinib, an oral Bruton's tyrosine kinase inhibitor, in pemphigus

BACKGROUND

The treatment of pemphigus is based on systemic corticosteroid use and adjuvant therapies, but some patients are resistant to conventional therapy. Tirabrutinib is a highly selective oral Bruton's tyrosine kinase inhibitor that may be clinically effective in treating pemphigus by suppressing B-cell signaling.

OBJECTIVE

We investigated the efficacy and safety of tirabrutinib in patients with refractory pemphigus.

METHODS

This was a multicenter, open-label, single-arm phase 2 study of Japanese patients with refractory pemphigus receiving appropriate treatment with an oral corticosteroid and adjuvant therapies. Patients received postprandial oral tirabrutinib 80 mg once daily for 52 weeks. After 16 weeks of tirabrutinib treatment, the corticosteroid dose was tapered to ≤10 mg/day of prednisolone equivalent.

RESULTS

In total, 16 patients were evaluated (mean age, 52.5 years; 50 % male). The complete remission rate after 24 weeks of treatment (primary endpoint) was 18.8 % (3/16; 95 % confidence interval, 6.6 %-43.0 %). By Week 52, eight patients (50.0 %) achieved complete remission and 10 patients (62.5 %) achieved remission. Over 52 weeks of treatment, the mean prednisolone dose decreased from 17.03 to 7.65 mg/day. Incidences of adverse events (AEs) and adverse drug reactions were 87.5 % and 43.8 %, respectively. A relationship with tirabrutinib was ruled out for all serious AEs and Grade ≥3 AEs.

CONCLUSION

Treatment with tirabrutinib enabled remission and reduced oral corticosteroid exposure over time and did not result in any major safety concerns in patients with refractory pemphigus. Thus, oral tirabrutinib may be a new treatment option for patients with refractory pemphigus.

Autoimmunity and immunological tolerance in autoimmune bullous diseases

Autoimmune diseases are devastating conditions in which the immune system is directed against the host, leading to life-threatening destruction of organs. Although autoantigens are ill-defined in most autoimmune diseases, this is not the case in the skin. Autoimmune bullous diseases have been extensively studied with detailed characterization of autoantigens, the epitopes that are targeted, and the mechanisms of action that mediate autoimmune tissue destruction. Pemphigus is an autoimmune bullous disease caused by circulating IgG that targets two desmosomal proteins, desmoglein 1 and 3, which are crucial for cell-cell adhesion of keratinocytes. Binding of auto-antibodies to desmogleins impairs keratinocyte adhesion, leading to severe blistering disease. Mouse models that recapitulate the human disease have been instrumental in elucidating the detailed pathophysiology. Taking advantage of the fact that desmogleins are specifically targeted in pemphigus, studying humoral and cellular autoimmunity against these autoantigens provides us with an opportunity to understand not only the effector mechanisms of B and T cells in mediating pathology but also how autoreactive lymphocytes are regulated during development in the thymus and post-development in the periphery. This review introduces pemphigus and its subtypes as prototypic autoimmune diseases from which recent basic and translational developments should provide insight into how autoimmunity develops.

Pemphigus Vulgaris and Foliaceus IgG Autoantibodies Directly Block Heterophilic Transinteraction between Desmoglein and Desmocollin

Anti-desmoglein (Dsg) 1 and Dsg3 IgG autoantibodies in pemphigus foliaceus and pemphigus vulgaris cause blisters through loss of desmosomal adhesion. It is controversial whether blister formation is due to direct inhibition of Dsg, intracellular signaling events causing desmosome destabilization, or both. Recent studies show that heterophilic binding between Dsg and desmocollin (Dsc) is the fundamental adhesive unit of desmosomes. To eliminate cellular contributions to potential pathogenicity of pemphigus antibodies, bead assays coated with recombinant Dsg1, Dsc1, Dsg3, or Dsc3 ectodomains were developed. A mixture of Dsg beads and Dsc beads formed large aggregates, confirming that the heterophilic binding is dominant. The pathogenic anti-Dsg1 and anti-Dsg3 mAbs, which bind the transadhesive interface, blocked the aggregation of Dsg1/Dsc1 and Dsg3/Dsc3 beads, respectively, whereas nonpathogenic mAbs did not. All sera tested from eight patients with pemphigus foliaceus and eight patients with mucosal pemphigus vulgaris with active disease inhibited the adhesion of Dsg1/Dsc1 and Dsg3/Dsc3 beads, respectively. When paired sera obtained from seven patients with pemphigus foliaceus and six patients with pemphigus vulgaris in active disease and remission were compared, the former inhibited aggregation better than the latter. These findings strongly suggest that steric hindrance of heterophilic transinteraction between Dsg and Dsc is important for disease pathology in both pemphigus foliaceus and pemphigus vulgaris.

Japanese guidelines for the management of pemphigoid (including epidermolysis bullosa acquisita)

The pemphigoid group is a category of autoimmune subepidermal blistering diseases in which autoantibodies deposit linearly at the epidermal basement membrane zone (BMZ). The main subtypes of pemphigoid mediated by immunoglobulin G autoantibodies are bullous pemphigoid (BP), mucous membrane pemphigoid (MMP) and epidermolysis bullosa acquisita (EBA). To establish the first guidelines approved by the Japanese Dermatological Association for the management of pemphigoid diseases, the Committee for Guidelines for the Management of Pemphigoid Diseases (Including EBA) was founded as part of the Study Group for Rare Intractable Skin Diseases under the Ministry of Health, Labor and Welfare Research Project on Overcoming Intractable Diseases. These guidelines aim to provide current information for the management of BP, MMP and EBA in Japan. Based on evidence, the guidelines summarize the clinical and immunological manifestations, pathophysiologies, diagnostic criteria, disease severity determination criteria, treatment algorithms and treatment recommendations. Because of the rarity of these diseases, there are few clinical studies with a high degree of evidence, so several parts of these guidelines were established based on the opinions of the Committee. To further optimize these guidelines, periodic revision in line with the new evidence is necessary.

Basement membrane zone IgE deposition is associated with bullous pemphigoid disease severity and treatment results

BACKGROUND

A subset of patients with bullous pemphigoid (BP) show deposition of IgE in the basement membrane zone (BMZ), yet the relationship between BMZ IgE and the clinical presentation of BP remains unclear.

OBJECTIVES

To investigate the relationship between IgE deposition, IgE levels in serum, and disease severity in patients with BP.

METHODS

We investigated IgE autoantibodies in 53 patients with BP by direct immunofluorescence (DIF), indirect immunofluorescence and enzyme-linked immunosorbent assay.

RESULTS

Of 53 patients with BP, 23 (43%) had IgE deposition, 10 (19%) of whom were IgE+ and 13 (25%) IgE± according to DIF analyses. Erosion/blister (E/B) Bullous Pemphigoid Disease Area Index (BPDAI) scores were significantly higher in IgE+ patients than in IgE- patients (n = 15), while no significant differences were found for urticaria/erythema BPDAI scores. IgE+ and IgE± patients took longer to reduce their E/B BPDAI score by 75% after systemic corticosteroid treatment. BP180-IgE levels were significantly higher among IgE+ patients than IgE± or IgE- patients (n = 10). Total IgE levels in the serum and blood eosinophil counts did not differ between IgE+, IgE± and IgE- patients. A significant correlation was detected between BP180-IgG and BP180-IgE, but not between BPDAI scores and any of BP180-IgG, BP180-IgE or blood eosinophil count.

CONCLUSIONS

IgE deposition in the BMZ is associated with higher E/B BPDAI scores and longer treatment periods. We conclude that IgE binding in the BMZ may contribute to BP pathogenesis by promoting blister formation. What's already known about this topic? BP180-IgE autoantibodies have an important role in the pathogenesis of bullous pemphigoid (BP). A subset of patients with BP display deposition of IgE within the basement membrane zone (BMZ) of skin tissue. What does this study add? Patients with in vivo IgE deposition in the BMZ displayed higher erosion/blister Bullous Pemphigoid Disease Area Index (BPDAI) scores, while urticaria/erythema BPDAI scores were not significantly different. Patients with in vivo IgE deposition in the BMZ took longer to reduce their erosion/blister BPDAI score by 75% after systemic corticosteroid treatment. BP180-specific IgE levels in serum were higher among patients with linear IgE deposition in the BMZ than in those with granular or no IgE deposition.

Patient voice on management of facial dermatological adverse events with targeted therapies: a qualitative study

BACKGROUND

With the increased use of targeted therapies in oncology, dermatological adverse events (dAEs) have drawn attention. Because the face is crucial for human identity and social interactions, facial dAEs have significant impact on a patient's quality of life. This study aimed to explore patients' experience with regard to the management of targeted oncological therapy-induced facial dAEs.

METHODS

In this qualitative study, 20 patients at a university hospital in Japan with advanced/metastatic cancer and targeted therapy-induced facial dAEs were individually interviewed to collect data. Thematic analysis was used to analyze the data.

RESULTS

Patients with cancer and targeted oncological therapy-induced facial dAEs who were referred to the Department of Dermatology had certain expectations from specialist services. Three key themes were identified: professional input and advice, empathetic commitment to individual management, and integrated care across specialties.

CONCLUSIONS

The referred patients with cancer and facial dAEs needed more in-depth information and advice from dermatological services and were reassured by the empathetic commitment to individual management in integrated care across specialties. These findings suggest that attention to the patient's perspective with a "sick person first" attitude and a collaborative effort across different specialties is important to minimize the effects of facial dAEs on the quality of life of patients with cancer.

Rituximab therapy for refractory autoimmune bullous diseases: A multicenter, open-label, single-arm, phase 1/2 study on 10 Japanese patients

This was a multicenter study of rituximab, a chimeric monoclonal immunoglobulin G antibody directed against CD20, for the treatment of refractory autoimmune bullous diseases (pemphigus and pemphigoid). Ten patients (three with pemphigus vulgaris, six with pemphigus foliaceus and one with bullous pemphigoid) were treated with a single cycle of rituximab (four weekly infusions at a dose of 375 mg/m² of body surface area). The primary end-points were the number of serious adverse events and rate of complete remission at 40 weeks. Five patients (50%) achieved complete remission with minimal therapy (defined as no active lesions with lower doses of systemic corticosteroids compared to that with prednisolone 10 mg/day). Improvements in clinical scores (Pemphigus Disease Area Index) and decreases in autoantibody titers in the sera were observed in the four pemphigus patients who failed to achieve complete remission. This suggests that rituximab was effective in nine of 10 cases. Two serious adverse events (Pneumocystis carinii pneumonia and septic shock due to infectious arthritis) were observed and adequately treated with hospitalization. CD19-positive B lymphocytes in the peripheral blood decreased on day 29 following rituximab treatment, and remained at low levels throughout the observation period (280 days). Our results confirmed the efficacy of rituximab therapy for refractory autoimmune bullous diseases in Japan.

Perspective From the 5th International Pemphigus and Pemphigoid Foundation Scientific Conference

The 5th Scientific Conference of the International Pemphigus and Pemphigoid Foundation (IPPF), “Pemphigus and Pemphigoid: A New Era of Clinical and Translational Science” was held in Orlando, Florida, on May 15–16, 2018. Scientific sessions covered recent, ongoing, and future clinical trials in pemphigus and bullous pemphigoid, disease activity and quality of life instruments, and the IPPF Natural History Study. Furthermore, the meeting provided an opportunity to hear firsthand from patients, investigators, and industry about their experience enrolling for clinical trials.

Recent advances in the understanding and treatment of pemphigus and pemphigoid

Pemphigus and pemphigoid are characterized as autoimmune blistering diseases in which immunoglobulin G autoantibodies cause blisters and erosions of the skin or mucosa or both. Recently, understanding of the pathophysiology of pemphigus and pemphigoid has been furthered by genetic analyses, characterization of autoantibodies and autoreactive B cells, and elucidation of cell–cell adhesion between keratinocytes. For the management of pemphigus and pemphigoid, the administration of systemic corticosteroids still represents the standard treatment strategy; however, evidence of the efficacy of therapies not involving corticosteroids, such as those employing anti-CD20 antibodies, is increasing. The goal should be to develop antigen-specific immune suppression-based treatments.

Correction: Paraneoplastic autoimmune multiorgan syndrome and paraneoplastic pemphigus describe the same spectrum of disease pathology

This corrects the article DOI: 10.1038/nrdp.2018.13.

Diagnosis and management of pemphigus: Recommendations of an international panel of experts

BACKGROUND

Several European countries recently developed international diagnostic and management guidelines for pemphigus, which have been instrumental in the standardization of pemphigus management.

OBJECTIVE

We now present results from a subsequent Delphi consensus to broaden the generalizability of the recommendations.

METHODS

A preliminary survey, based on the European Dermatology Forum and the European Academy of Dermatology and Venereology guidelines, was sent to a panel of international experts to determine the level of consensus. The results were discussed at the International Bullous Diseases Consensus Group in March 2016 during the annual American Academy of Dermatology conference. Following the meeting, a second survey was sent to more experts to achieve greater international consensus.

RESULTS

The 39 experts participated in the first round of the Delphi survey, and 54 experts from 21 countries completed the second round. The number of statements in the survey was reduced from 175 topics in Delphi I to 24 topics in Delphi II on the basis of Delphi results and meeting discussion.

LIMITATIONS

Each recommendation represents the majority opinion and therefore may not reflect all possible treatment options available.

CONCLUSIONS

We present here the recommendations resulting from this Delphi process. This international consensus includes intravenous CD20 inhibitors as a first-line therapy option for moderate-to-severe pemphigus.

Vancomycin Mediates IgA Autoreactivity in Drug-Induced Linear IgA Bullous Dermatosis

Vancomycin (VCM) is known to induce linear IgA bullous dermatosis (LAD). However, in contrast to conventional LAD, in which circulating IgA autoantibodies against basement membrane proteins are commonly detected, patient sera from VCM-induced LAD yields negative results in indirect immunofluorescence microscopy, and the targeted autoantigen remains undetermined. By using sera from a typical patient with VCM-induced LAD, we identified that co-incubation of sera with VCM resulted in linear IgA deposition at the basement membrane zone by indirect immunofluorescence. Patient sera reacted with the dermal side of 1 mol/L NaCl-split skin and with the recombinant noncollagenous (i.e., NC1) domain of type VII collagen by both immunoblot and ELISA in the presence of VCM. The investigation of an additional 13 patients with VCM-induced LAD showed that 10 out of the 14 sera (71.4%) reacted with the NC1 domain of type VII collagen by ELISA when spiked with VCM, whereas only 4 (28.6%) tested positive without it. The enhancement of reactivity to NC1 by VCM, as determined by optical density via ELISA, was observed in 10 out of the 14 sera (71.4%). These findings indicate that type VII collagen is a target autoantigen in VCM-induced LAD and that VCM mediates IgA autoreactivity against type VII collagen, providing an insight into mechanisms involved in drug-induced autoimmune disease.