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

Autoimmune bullous diseases: pathogenesis and clinical management

Autoimmune bullous diseases (AIBDs) represent a heterogeneous group of immune-mediated disorders characterized by life-threatening blistering of the skin and mucous membranes. This Review synthesizes current understanding of AIBD pathogenesis, clinical phenotypes, diagnostic approaches, and therapeutic strategies, emphasizing recent advancements and translational opportunities. At the core of AIBDs is autoantibody-mediated disruption of structural proteins in the epidermis or basement membrane zone, particularly at desmosomal and hemidesmosomal junctions. Key subtypes, including pemphigus, paraneoplastic pemphigus, pemphigoid, and IgA-related diseases, are distinguished by their target antigens, clinical manifestations, and immunopathological profiles. Diagnostic workflows rely on direct immunofluorescence, and serological assays, yet subtype differentiation remains challenging due to overlapping features. Traditional therapies, such as systemic corticosteroids and immunosuppressants, have improved outcomes but are limited by toxicity. Recent breakthroughs highlight targeted interventions, including B-cell depletion with rituximab, cytokine modulation via dupilumab, and JAK inhibitors for inflammatory pathways. Innovative strategies like chimeric autoantibody receptor T-cell (CAART) therapy further address refractory cases by eliminating autoreactive B cells. Additionally, the Review underscores the emerging role of inflammation-driven mechanisms and the necessity of multidisciplinary care, given AIBDs' associations with malignancies, autoimmune comorbidities. Despite progress, challenges persist in early diagnosis, personalized therapy optimization, and understanding antigen-specific immune responses. Future directions include refining diagnostic biomarkers, exploring novel targets, and developing precision medicine approaches.

Lipid Profile Scores Predict Severity of Pemphigus: A Cross-Sectional Study

Background

There is little evidence about the relationship between lipid indices and the severity of pemphigus vulgaris (PV) disease. In this cross-sectional study, we try to find out the exact relationship between three dietary lipid indices (PUFA/SFA ratio and ω-6/ω-3 index) and the severity of PV disease.

Methods

In this hospital-based cross-sectional study, a total of 138 pemphigus vulgaris cases were studied, of which 108 had PDAI ≤15, and 30 had PDAI>15. Dietary intakes were measured a valid 168-item FFQ. To calculate the lipid indices, the data received from diet were used.

Results

After adjusting for potential confounders, people with the highest ω-6/ω-3 index had 32% lowest severity of PV disease compared to the people in the lowest category. However, this association was not significant in all models (OR: 0.68; 95% CI: 0.24-1.93, P trend = 0.47). Moreover, people with the highest PUFA/SFA index had 9% highest severity of PV disease compared to the people in the lowest category. However, this association was not significant in all models (OR: 1.09; 95% CI: 0.34-3.51, P trend = 0.88).

Conclusion

The evidence of our study shows that the relation between PUFA/SFA ratio and ω-6/ω-3 index is not significant. However, case-control studies are needed to confirm these findings.

The role of BATF in immune cell differentiation and autoimmune diseases

As a member of the Activator Protein-1 (AP-1) transcription factor family, the Basic Leucine Zipper Transcription Factor (BATF) mediates multiple biological functions of immune cells through its involvement in protein interactions and binding to DNA. Recent studies have demonstrated that BATF not only plays pivotal roles in innate and adaptive immune responses but also acts as a crucial factor in the differentiation and function of various immune cells. Lines of evidence indicate that BATF is associated with the onset and progression of allergic diseases, graft-versus-host disease, tumors, and autoimmune diseases. This review summarizes the roles of BATF in the development and function of innate and adaptive immune cells, as well as its immunoregulatory effects in the development of autoimmune diseases, which may enhance the current understanding of the pathogenesis of autoimmune diseases and facilitate the development of new therapeutic strategies.

Quality-controlled characterization of a monoclonal antibody specific to an EC5-domain of human desmoglein 3 for pemphigus research

Background

Pemphigus vulgaris (PV) is a life-threatening autoimmune blistering disease caused mainly by IgG autoantibodies (auto-abs) against the cadherin-type adhesion molecules desmoglein (Dsg) 1 and 3. Pathogenic anti-Dsg3 auto-abs bind to different Dsg3 epitopes, leading, among others, to signalling that is involved in pathogenic events, such as Dsg3 depletion. As central tools in research on PV, a limited number of antibodies such as AK23 are frequently used by the autoimmune bullous disease community.

Methods

Previously, we have introduced a novel Dsg3 EC5-binding antibody termed 2G4 that may potentially serve as a superior tool for numerous PV related analysis. The purpose of this study was to develop a quality-controlled production and verification process that allows I) a continuous quality improvement, and II) a verified and comprehensible overall quality with regard to pathogenic antigen-specific binding in a variety of pemphigus assays for each batch production.

Results

Thus, a workflow based on a standardized operating procedure was established. This includes the verification of purity and in-vitro binding capacity (SDS-page, direct and indirect immunofluorescence) as primary parameters, and size analysis by mass-spectrometry and ex-vivo pathogenicity by monolayer dissociation assay.

Conclusion

We here present an extensive point-by-point quality controlled IgG production protocol, which will serve as a basis for a standardized antibody assessment in PV research.

Immunostimulatory effects of Toll-like receptor ligands as adjuvants in establishing a novel mouse model for pemphigus vulgaris

BACKGROUND

The meticulous selection of appropriate vaccine adjuvants is crucial for optimizing immune responses. Traditionally, pemphigus vulgaris (PV), an autoimmune disorder, has been modelled using complete Freund's adjuvant (CFA). In this study, we aimed to discern potential variations in immune responses elicited by Toll-like receptor (TLR) ligands as compared to CFA.

METHODS

A comprehensive investigation was conducted, comparing the effects of these adjuvants in conjunction with ovalbumin or desmoglein-3. Flow cytometry was employed to analyse distinct cell subsets, while enzyme-linked immunosorbent assay quantified antigen-specific antibodies and cytokine levels. Histological examination of harvested skin tissues and transcriptome analysis of skin lesions were performed to identify differentially expressed genes.

RESULTS

TLR ligands demonstrated efficacy in inducing PV-like symptoms in wild-type mice, in contrast to CFA. This underscored the substantial impact of the adjuvant on self-antigen tolerance. Furthermore, we proposed an enhanced method for establishing a PV model through adoptive transfer, substituting CFA with TLR ligands. Our results revealed that in contrast to the perception that CFA being the most potent immunopotentiator reported, CFA promoted regulatory T cells (Treg), follicular regulatory T cells and IL-10-producing neutrophils, whereas TLR ligands downregulated CCL17 and IL-10. This suggested potential implications for the recruitment and activation of Treg subsets. While B cell and CD8+ T cell responses exhibited similarity, CFA induced less activation in dendritic cell subsets. A novel mouse model of PV and systemic comparison of immunostimulatory effects of adjuvants were provided by this study.

CONCLUSIONS

The systematic comparison of CFA and TLR ligands shed light on the distinctive properties of these adjuvants, presenting innovative mouse models for the investigation of pemphigus. This study significantly contributes to adjuvant research and advances our understanding of PV pathogenesis.

KEY POINTS/HIGHLIGHTS

Immunization with desmoglein 3 and Toll-like receptor (TLR) ligands effectively induces pemphigus symptoms in wild-type mice, whereas complete Freund's adjuvant (CFA) fails. TLR ligands heightened the autoreactivity of donor cells in the adoptive transfer pemphigus model. CFA promoted regulatory T cells and IL-10-producing neutrophils, whereas TLR ligands downregulated CCL17 and IL-10, leading to more effective immune responses.

From neglect to spotlight: the underappreciated role of B cells in cutaneous inflammatory diseases

The skin, covering our entire body as its largest organ, manifests enormous complexities and a profound interplay of systemic and local responses. In this heterogeneous domain, B cells were considered strangers. Yet, recent studies have highlighted their existence in the skin and their distinct role in modulating cutaneous immunity across various immune contexts. Accumulating evidence is progressively shedding light on the significance of B cells in maintaining skin health and in skin disorders. Herein, we integrate current insights on the systemic and local contributions of B cells in three prevalent inflammatory skin conditions: Pemphigus Vulgaris (PV), Systemic Lupus Erythematosus (SLE), and Atopic Dermatitis (AD), underscoring the previously underappreciated importance of B cells within skin immunity. Moreover, we address the potential adverse effects of current treatments used for skin diseases, emphasizing their unintentional consequences on B cells. These comprehensive approaches may pave the way for innovative therapeutic strategies that effectively address the intricate nature of skin disorders.

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.