Abstract: SA-PO0719
Transglutaminase-2 Specific IgA-Producing Plasma Cells in Experimental IgAN
Session Information
- Glomerular Diseases: Profiling Through Multiomics
November 08, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Makita, Yuko, Toronto General Hospital, Toronto, Ontario, Canada
- Haniuda, Kei, University of Toronto, Toronto, Ontario, Canada
- Murphy, Julia M., University of Toronto, Toronto, Ontario, Canada
- Mak, Martin L., University of Toronto, Toronto, Ontario, Canada
- Suzuki, Yusuke, Juntendo Daigaku, Bunkyo, Tokyo, Japan
- Crome, Sarah Q., University of Toronto, Toronto, Ontario, Canada
- Gommerman, Jennifer, University of Toronto, Toronto, Ontario, Canada
- Reich, Heather N., Toronto General Hospital, Toronto, Ontario, Canada
Background
The trigger and source of pathogenic IgA production in IgAN remain unclear. Our previous work suggested that with BAFF overexpression in experimental IgAN (BAFF-Tg mouse), IgA antibody-producing cells (IgA-APCs) are detected within the kidneys. We hypothesize that BAFF overexpression creates a de novo niche for gut-derived IgA+ plasma cells (PCs) in the kidney. Once established, BAFF-dependent IgA+ PCs elaborate tissue-resident pathology. We sought to localize and characterize IgA-APCs in experimental IgAN and explore mechanisms promoting their kidney localization.
Methods
We used flow cytometry, scRNA-seq, immunofluorescence, ELISPOT, and spatial transcriptomics (Xenium) to compare kidneys from BAFF-Tg and wild-type (WT) mice.
Results
We confirmed an increase in IgA+ PCs (CD45+B220-CD98+IRF4+IgA+) in BAFF-Tg but not WT kidneys by flow cytometry and scRNA-seq. Ligand-receptor analysis supported interactions between kidney endothelial cells and IgA-PCs. Spatial transcriptomic data indicated that the glomerular microenvironment in BAFF-Tg mice was enriched with immune cells and showed increased cytokine expression supporting of an immune-activated niche. Differential scRNA-seq analysis revealed increased endothelial expression of transglutaminase 2 (Tgm2) in BAFF-Tg mice (p<0.05), a protein implicated in IgAN. We confirmed increased glomerular and tubulo-interstitial Tgm2 RNA expression by spatial transcriptomics and corresponding increased Tgm2 protein by immunofluorescence. Since Tgm2 can be targeted by IgA in settings like celiac disease, we developed a custom ELISPOT to assess the Tgm2 specificity of IgA. Tgm2-specific IgA-PCs were observed in both intestine and kidneys of BAFF-Tg but not WT mice.
Conclusion
Tgm2-specific IgA-PCs are present in BAFF-Tg kidneys. Increased endothelial Tgm2 expression in intestines and glomeruli suggests Tgm2 may act as an autoantigen in the context of BAFF overexpression. Further study is needed to determine if Tgm2-specific IgA-PCs causally drive IgAN.