Case Report: Variety of Target Antigens During 1 Year Follow-Up of a Patient Initially Diagnosed With Bullous Pemphigoid

Diagnostic methods and strategies for autoimmune bullous diseases

INTRODUCTION

Autoimmune bullous disease (AIBD), showing blistering lesions on the skin and/or mucous membranes, is characterized by autoantibodies against various structural molecules present in keratinocyte cell surfaces and epidermal basement membrane zone. In addition to the clinical and pathological features, identification of specific autoantibodies is essential for AIBD diagnosis, and therefore corresponding methods should be well summarized and popularized.

AREA COVERED

Currently, direct immunofluorescence using biopsy tissue specimen and indirect immunofluorescence using normal human skin, 1 M NaCl-split skin and rat bladder are primarily used to identify tissue-bound and circulating autoantibodies, respectively. Immunoblotting and enzyme-linked immunosorbent assay (ELISA) methods have been developed for detection of autoantibodies against AIBD autoantigens, including desmoglein 1, desmoglein 3, BP180, BP230, type VII collagen, laminin (LM) 332, integrin α6β4, p200 (LMγ1/LMβ4) and human serum albumin. In this review, we summarized the detailed laboratory protocols for AIBD diagnosis methods used in our three institutes (Kurume University and Osaka Metropolitan University in Japan, and Daqing Oilfield General Hospital in China) before 9 October 2024.

EXPERT OPINION

This review will benefit both clinical practitioners and basic researchers on AIBD. In the future, simpler and easier AIBD diagnostic algorithms using a smaller number of tests should be established.

Classification and Antigen Molecules of Autoimmune Bullous Diseases

Autoimmune bullous diseases (AIBDs), which are a group of tissue-specific autoimmune diseases of the skin, present with various blistering lesions on the skin and mucous membranes, and show autoantibodies of IgG, IgA and IgM against epidermal cell surfaces and basement membrane zone. To date, AIBDs have been classified into a number of distinct subtypes by clinical and histopathological findings, and immunological characteristics. In addition, various biochemical and molecular biological studies have identified various novel autoantigens in AIBDs, which has resulted in proposals of new subtypes of AIBDs. In this article, we summarized various distinct AIBDs, and proposed the latest and most comprehensive classification of AIBDs with their autoantigen molecules.

Case report: Mucous membrane pemphigoid with complicated autoantibody profile indicating the necessity of comprehensive diagnostic methods and the contribution of IgA autoantibodies

Mucous membrane pemphigoid (MMP) is a type of subepithelial autoimmune bullous disease, affecting various mucosae, occasionally with skin lesions. Both diagnosis and treatment of MMP are difficult. Although multiple autoantigens have been identified for MMP, the pathogenesis of MMP is still unclear. In this study, we presented a female MMP case with extensive oral mucosal lesions and skin lesions, particularly on the extremities. IgG and IgA autoantibodies against multiple autoantigens including BP180, laminin 332, integrinα6β4 and desmoglein 3, and IgM autoantibodies against BP180 were identified during the disease course. Compared with IgG autoantibodies, the levels of IgA autoantibodies against various autoantigens decreased more significantly with improvement of clinical features after the initiation of treatments. Our findings indicated the importance of comprehensive autoantibody screening for different immunoglobulin types and autoantigens at multiple time points for the precise diagnosis of various autoimmune bullous diseases, and the significant involvement of IgA autoantibodies into the pathogenesis of MMP.