Abstract: TH-PO0441
Enhanced Serum IgA Reactivity to Gut Microbiota in IgAN Supports a Mucosal Origin of Pathogenic IgA
Session Information
- Glomerular Diseases: Autoimmune Diseases
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Arbez, Laure, GIMAP INSERM U1111 CIRI, Saint Etienne, France
- Mariat, Christopher R., CHU Saint Etienne, Saint Etienne, France
- Paul, Stéphane, CHU Saint Etienne, Saint Etienne, France
- Maillard, Nicolas, CHU Saint Etienne, Saint Etienne, France
Background
IgA nephropathy (IgAN) is characterized by galactose-deficient IgA1 and immune complex deposition within glomeruli. Increasing evidence suggests a mucosal origin of pathogenic IgA linked to intestinal dysbiosis. We investigated serum IgA reactivity against gut bacterial antigens in patients with IgAN.
Methods
An ELISA-based assay was developed using lysates from intestinal bacterial species coated onto ELISA plates. Serum samples from patients with biopsy-proven IgAN at time of diagnosis and healthy controls were incubated with bacterial antigens, and bound IgA were detected using HRP-conjugated anti-human IgA antibodies. Serum secretory IgA (SIgA) concentrations and correlations with bacteria-specific IgA reactivity were analyzed.
Results
Patients with IgAN exhibited significantly increased serum IgA reactivity against Faecalibacterium prausnitzii, Flavonifractor plautii, Bifidobacterium longum, and Lactobacillus rhamnosus compared with healthy controls (all p<0.0001). Significant but less pronounced differences were also observed for Akkermansia muciniphila and Bacteroides thetaiotaomicron (p<0.05). Serum SIgA levels positively correlated with reactivity against Flavonifractor plautii (p=0.002), Bifidobacterium longum (p=0.003), and Akkermansia muciniphila (p=0.004).
Conclusion
These preliminary findings support a mucosal and microbiota-related origin of aberrant circulating IgA in IgAN. The association between SIgA and bacteria-specific serum IgA responses further supports the role of the gut–kidney axis in IgAN pathophysiology and provides rationale for mucosal-targeted therapeutic strategies.