Abstract: FR-PO793
T Cell Hyporesponsiveness in Focal Segmental Glomerulosclerosis Responsive to Rituximab Is Associated with B Cell Activation and Production of Podocyte Damaging Factors
Session Information
- Glomerular Diseases: Inflammation and Immunology
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Lu, Liangjian, National University Health System, Singapore, Singapore, Singapore
- Chan, Chang-Yien, National University of Singapore, Singapore, Singapore
- Teo, Sharon, National University Health System, Singapore, Singapore, Singapore
- Ng, Kar Hui, National University of Singapore, Singapore, Singapore
- Yap, Hui Kim, National University of Singapore, Singapore, Singapore
Background
The mechanistic basis of Rituximab response in idiopathic nephrotic syndrome (INS) remains uncertain. We previously showed that Rituximab-response in childhood-onset focal segmental glomerulosclerosis (FSGS) was associated with T-cell hypo-responsiveness. We aimed to investigate if dysregulated B-cell activity was associated with T-cell hypo-responsiveness prior to Rituximab.
Methods
37 patients with childhood-onset FSGS were recruited. Rituximab was administered for clinical indications, with response defined as the ability to wean off steroids and calcineurin inhibitors by 3 months after Rituximab while remaining in complete remission. T-cell hypo-responsiveness was determined by stimulated INFγ production <2.5%. B-cell activation was measured by flow cytometry of activation markers and multiplexed cytokine analysis without further stimulation. Podocytes were incubated with B-cell conditioned media, and stained for F-actin with phalloidin. Staining was scored from 0-3, with higher scores reflecting greater abnormality, i.e. more cortical F-actin and less stress fibres. Comparison between groups was performed using t-test, Wilcoxon rank-sum test or Fisher’s exact test.
Results
Baseline T-cell hypo-responsiveness was associated with Rituximab response (65% vs 29%, p=0.049). Comparing T-cell hypo-responsive and normo-responsive patients, total CD19+ B-cells were unchanged (p=0.6), but CD19+ CD80+ B-cells were increased (16% (IQR 11-26) vs 5% (IQR 5-9), p=0.006). There was a striking upregulation in resting B-cell cytokine production in patients with T-cell hypo-responsiveness, including INFγ (p= 0.005), IP10 (p=0.014) and TNFα (p=0.022). Podocytes incubated with B-cell conditioned medium from T-cell hypo-responsive patients demonstrated increased F-actin score (2.05±0.11 vs 1.36±0.15, p=0.02), but not when B-cells from T-cell normo-responsive patients were used (p=0.14). Repeat analysis 6 months post-Rituximab revealed no differences in B-cell cytokine production.
Conclusion
The association between Rituximab response and T-cell hypo-responsiveness likely reflects underlying B-cell activation, with B-cell mediated production of podocyte damaging factors. T-cell hypo-responsiveness may be an epiphenomenon reflecting T-cell exhaustion from chronic B-cell stimulation.
Funding
- Government Support – Non-U.S.