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Enzyme Replacement Therapy Clears Gb3 Deposits from a Podocyte Cell Culture Model of Fabry Disease but Fails to
Fabian Braun1,2,3,4, Linda Blomberg1,2,3, Susanne Brodesser2
1Department II of Internal Medicine and Center for Rare Diseases Cologne, University Hospital of Cologne, Cologne, Germany.
Background/Aims:
Fabry disease (FD) is a lysosomal storage disorder characterized by impaired alpha-galactosidase A (α-Gal A) enzyme activity due to mutations in the GLA gene. While virtually all tissues are affected, renal damage is particularly critical for the patients' outcome. Currently, powerful diagnostic tools and in vivo research models to study FD in the kidney are lacking, which is a major obstacle for further improvements in diagnosis and therapy. The present study focuses on the effects of enzyme replacement therapy on a previously established podocyte cell culture model of Fabry disease.
Methods:
We investigated the effect of in vitro application of α-Gal A on Fabry podocytes for 3 days, mimicking enzyme replacement therapy. We studied reduction of Gb3 levels and dysregulated molecular pathways such as autophagy, mTOR/AKT signaling and pro-fibrotic signaling by employing immunofluorescence, electron microscopy, tandem mass spectrometry and western blot.
Results:
We detected complete resolution of Gb3 accumulation in Fabry podocytes upon α-Gal A treatment. Despite robust Gb3 clearance, dysregulation of the signaling pathways investigated was not reversed.
Conclusion:
This study presents first evidence for Gb3-independent effects regarding dysregulation of signal transduction mechanisms in FD not recovering upon α-Gal A treatment. We assume that intracellular alterations observed in FD may have a point of no return after which a reversal of dysregulated cellular signal transduction by α-Gal A treatment is not effective, despite Gb3 clearance. Our observations suggest further research on signal transduction mechanisms altered in Fabry podocytes and on determining the appropriate time for initiation of Fabry therapy.
Insights
Enzyme replacement therapy cleared Gb3 in Fabry disease podocytes but did not reverse key signaling pathway issues. This suggests potential irreversible cellular changes in Fabry disease, highlighting the need for timely treatment.
Area of Science:
- Nephrology
- Genetics
- Cell Biology
Background:
- Fabry disease (FD) is a genetic lysosomal storage disorder impacting multiple organs, with kidney damage being critical.
- Current diagnostic tools and research models for FD kidney disease are limited, hindering therapeutic advancements.
- Podocytes are crucial for kidney function and are affected in FD.
Purpose of the Study:
- To investigate the effects of enzyme replacement therapy (ERT) on a podocyte cell culture model of Fabry disease.
- To assess the impact of alpha-galactosidase A (α-Gal A) on Gb3 accumulation and molecular signaling pathways in Fabry podocytes.
Main Methods:
- Fabry disease podocytes were treated with α-Gal A in vitro for 3 days to simulate ERT.
- Gb3 levels, autophagy, mTOR/AKT signaling, and pro-fibrotic signaling were analyzed using immunofluorescence, electron microscopy, mass spectrometry, and western blot.
Main Results:
- α-Gal A treatment completely resolved Gb3 accumulation in Fabry podocytes.
- Despite successful Gb3 clearance, dysregulation in investigated signaling pathways (autophagy, mTOR/AKT, pro-fibrotic) persisted.
- Gb3-independent molecular alterations were observed in Fabry podocytes post-treatment.
Conclusions:
- This study provides evidence for Gb3-independent signaling dysregulation in Fabry disease that is not reversed by α-Gal A treatment.
- Intracellular changes in FD may become irreversible, limiting the efficacy of ERT even after Gb3 clearance.
- Further research is needed on altered signaling pathways and optimal timing for initiating Fabry disease therapy.
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