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Introduction: Oral lichen planus (OLP) is a common chronic inflammatory disorder of the oral mucosa with an unclear etiology. Several types of immune cells are involved in the pathogenesis of OLP., Methods: We used single-cell RNA sequencing and immune repertoire sequencing to characterize the mucosal immune microenvironment of OLP. The presence of tissue-resident memory CD8+ T cells are validated by multiplex immunofluorescence., Results: We generated a transcriptome atlas from four OLP biopsy samples and their paired peripheral blood mononuclear cells (PBMCs), and compared them with two healthy tissues and three healthy PBMCs samples. Our analysis revealed activated tissue-resident memory CD8+ T cells in OLP tissues. T cell receptor repertoires displayed apperant clonal expansion and preferrential gene pairing in OLP patients. Additionally, obvious BCR clonal expansion was observed in OLP lesions. Plasmacytoid dendritic cells, a subtype that can promote dendritic cell maturation and enhance lymphocyte cytotoxicity, were identified in OLP. Conventional dendritic cells and macrophages are also found to exhibit pro-inflammatory activity in OLP. Cell-cell communication analysis reveals that fibroblasts might promote the recruitment and extravasation of immune cells into connective tissue., Discussion: Our study provides insights into the immune ecosystem of OLP, serving as a valuable resource for precision diagnosis and therapy of OLP., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Li, Wang, Shi, Zhong, Duan, Kuang, Liu, Luo, Zhou, Jiang, Dan, Luo, Zhang, Chen, Zeng and Li.)

Mucous membrane pemphigoid (MMP) and anti-laminin (LM) γ1 pemphigoid, two subtypes of subepidermal autoimmune bullous diseases characterized by autoantibodies against epidermal basement membrane zone proteins, mainly show mucosal and skin lesions, respectively. The known autoantigens of MMP includes BP180, BP230, LM332, integrin α6β4 and type VII collagen, and anti-LMγ1 pemphigoid targets LMγ1. In this study, we present an unique MMP case with oral mucosal lesions, which showed positive IgA signals on basement membrane zone in indirect immunofluorescence using normal human skin and on dermal side in indirect immunofluorescence using salt-split skin, positive IgA autoantibodies against LMγ1 by immunoblotting of epidermal extracts, positive IgA autoantibodies against LMα5 by immunoblotting of LM521 recombinant protein (rLM521) and positive IgG autoantibodies against LMγ1 by immunoblotting of rLM111 and rLM521 at first visit (Day 0). After therapy, further serological analyses of serum samples collected at Day 30 and Day 50 indicated that IgA autoantibodies against LMγ1 were likely to be pathogenic. These results suggest that LMγ1 is another autoantigen of MMP, and our patient might be the first reported case of anti-LMγ1 MMP., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Kuang, Qian, Zhang, Li, Hashimoto, Zeng and Li.)