Autoimmune reactivity against precursor form of desmoglein 1 in healthy Tunisians in the area of endemic pemphigus foliaceus

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.

IgG4 autoantibodies and autoantigens in the context of IgG4-autoimmune disease and IgG4-related disease

Immunoglobulins are an essential part of the humoral immune response. IgG4 antibodies are the least prevalent subclass and have unique structural and functional properties. In this review, we discuss IgG4 class switch and B cell production. We review the importance of IgG4 antibodies in the context of allergic responses, helminth infections and malignancy. We discuss their anti-inflammatory and tolerogenic effects in allergen-specific immunotherapy, and ability to evade the immune system in parasitic infection and tumour cells. We then focus on the role of IgG4 autoantibodies and autoantigens in IgG4-autoimmune diseases and IgG4-related disease, highlighting important parallels and differences between them. In IgG4-autoimmune diseases, pathogenesis is based on a direct role of IgG4 antibodies binding to self-antigens and disturbing homeostasis. In IgG4-related disease, where affected organs are infiltrated with IgG4-expressing plasma cells, IgG4 antibodies may also directly target a number of self-antigens or be overexpressed as an epiphenomenon of the disease. These antigen-driven processes require critical T and B cell interaction. Lastly, we explore the current gaps in our knowledge and how these may be addressed.

From Insect Bites to a Skin Autoimmune Disease: A Conceivable Pathway to Endemic Pemphigus Foliaceus

In the endemic variants of pemphigus foliaceus (PF), in Brazil and Tunisia, patients generate pathogenic IgG4 anti-desmoglein 1 autoantibodies. Additionally, these patients possess antibodies against salivary proteins from sand flies that react with Dsg1, which may lead to skin disease in susceptible individuals living in endemic areas. This minireview focuses on recent studies highlighting the possible role of salivary proteins from Lutzomyia longipalpis (L. longipalpis) in EPF from Brazil and Phlebotomus papatasi (P. papatasi) in EPF from Tunisia. We will briefly discuss the potential mechanisms of molecular mimicry and epitope spreading in the initiation and development of endemic PF (EPF) in Brazil and Tunisia.

Assessment of the quality of life of Egyptian and Tunisian autoimmune bullous diseases' patients using an Arabic version of the autoimmune bullous disease quality of life and the treatment of autoimmune bullous disease quality of life questionnaires

BACKGROUND

The Autoimmune Bullous Disease Quality of Life (ABQOL) and the Treatment of Autoimmune Bullous Disease Quality of Life (TABQOL) questionnaires proved to be reliable tools that measure the disease and treatment burden.

OBJECTIVES

We aimed to assess the ABQOL and TABQOL in the Arabic population.

METHODS

The English questionnaires were translated into the Arabic language by a certified translation agency. Eighty autoimmune bullous disease (AIBD) patients were included in this study. Patients were asked to answer 2 questionnaires. After 1 week the same patients were asked to answer the same questionnaires again.

RESULTS

The age of the patients ranged from 19 to 81 years (mean=46), 19 males, 61 females. The ABQOL ranged from 0-37 (mean=16.4±9.2). The TABQOL ranged from 2-43 (mean=21.5±9.4). Test-retest reliability was acceptable, Cronbach's alpha was 0.76 for ABQOL and 0.74 for TABQOL. There was no significant correlation between the age of the patients and ABQOL, r =-0.2, p value was 0.183. There was a significant negative correlation between the age of the patients and the TABQOL, r=-0.2, p value was 0.039. There was a significant negative correlation between the education of the patients and the TABQOL, r=-0.3, p value was 0.007.

STUDY LIMITATIONS

Small sample size of some AIBDs and patients with severe disease.

CONCLUSION

Objective and valuable measurements such as ABQOL and TABQOL are now available to help physicians understand their patient's distress and should be used in every patient with AIBD. Younger and less educated patients appear to have more effects on their QOL from the treatments.

Pathogenic IgG4 autoantibodies from endemic pemphigus foliaceus recognize a desmoglein-1 conformational epitope

Fogo Selvagem (FS), the endemic form of pemphigus foliaceus, is mediated by pathogenic IgG4 autoantibodies against the amino-terminal extracellular cadherin domain of the desmosomal cadherin desmoglein 1 (Dsg1). Here we define the detailed epitopes of these pathogenic antibodies. Proteolytic footprinting showed that IgG4 from 95% of FS donor sera (19/20) recognized a 16-residue peptide (A129LNSMGQDLERPLELR144) from the EC1 domain of Dsg1 that overlaps the binding site for an adhesive-partner desmosomal cadherin molecule. Mutation of Dsg1 residues M133 and Q135 reduced the binding of FS IgG4 autoantibodies to Dsg1 by ∼50%. Molecular modeling identified two nearby EC1 domain residues (Q82 and V83) likely to contribute to the epitope. Mutation of these residues completely abolished the binding of FS IgG4 to Dsg1. Bead aggregation assays showed that native binding interactions between Dsg1 and desmocollin 1 (Dsc1), which underlie desmosome structure, were abolished by Fab fragments of FS IgG4. These results further define the molecular mechanism by which FS IgG4 autoantibodies interfere with desmosome structure and lead to cell-cell detachment, the hallmark of this disease.