Abstract: TH-PO0668
B Cell-Specific Deletion of C1GALT1 Elevates Serum Gd-IgA1 but Fails to Induce Mesangial IgA Deposition in Humanized IGHA1 Mice
Session Information
- Glomerular Diseases: Immunopathogenesis and Targeted Therapeutics
November 06, 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
- Wu, Jingyi, Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Zhang, Yuemiao, Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Zhang, Zhao, Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Li, Run, Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Zhou, Xu-jie, Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Gale, Daniel P., Department of Nephrology, University College of London, London, United Kingdom
- Jin, Jing, Department of Medicine, Division of Nephrology and Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
- Barratt, Jonathan, University of Leicester & Leicester General Hospital, Leicester, United Kingdom
- Lv, Jicheng, Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
- Zhang, Hong, Renal Division, Peking University First Hospital, Peking University Institute of Nephrology, Beijing, China
Background
In the pathogenesis of IgA nephropathy, the “four-hits” hypothesis implicates galactose-deficient IgA1 (Gd-IgA1) as a key initiator. Core 1 β1,3-galactosyltransferase (C1GALT1) catalyzes galactose addition to O-glycans on the IgA1 hinge region. In a humanized IgA nephropathy model, we deleted the C1GALT1 gene in B cells to assess the impact on (1) circulating Gd-IgA1 levels and (2) glomerular IgA1 deposition.
Methods
Humanized IGHA1ki/kic1galt1fl/flcd19-Cre mice with B cell–specific C1GALT1 deletion were treated with CFA or CFA-emulsified Lactobacillus casei cell wall extract (LCWE) to stimulate mucosal immunity. Serum and intestinal samples were collected longitudinally to measure hIgA1, Gd-IgA1, poly-IgA1, and IgA1–IgG complexes. Glomerular immune deposition and histopathology were assessed at various time points.
Results
Homozygous deletion of C1GALT1 in B cells markedly elevated serum and mucosal Gd-IgA1, comprising up to 80% of total IgA1, compared to 0.1% and 0.3% in IGHA1ki/ki and heterozygous controls, respectively. These mice also formed more IgA1-IgG immune complexes. However, even with CFA/LCWE stimulation, glomerular IgA and C3 deposition remained mild. In contrast, control mice with higher total IgA1 but lower Gd-IgA1 exhibited stronger mesangial deposition and pathology.
Conclusion
We used a genetic mouse model with extraordinarily high levels of Gd-IgA1 production to study its causative role of IgA deposition in the kidney. C1GALT1 deficiency in B cells resulted in Gd-IgA1 enrichment by 10 folds. This led to increased immune complex formation, which, in contradiction to the “four-hits” hypothesis, was nonetheless insufficient to induce IgAN-like glomerular injury. Instead, our findings suggest that Gd-IgA1 may serve as a biomarker of mucosal immune dysregulation rather than a direct pathogenic driver. Overall, high levels of mucosal derived IgA1 production, regardless of its galactose status, may contribute to the mesangial deposition.
Funding
- Government Support – Non-U.S.