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Kidney Week

Abstract: PO1603

Metabolic Dysfunction of Glomerular Endothelial Cells in Alport Syndrome

Session Information

Category: Genetic Diseases of the Kidneys

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Soloyan, Hasmik, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Thornton, Matthew Edward, University of Southern California, Los Angeles, California, United States
  • Villani, Valentina, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Khatchadourian, Patrick, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Cravedi, Paolo, Mount Sinai Health System, New York, New York, United States
  • Angeletti, Andrea, Orsola University, Bologna, Italy
  • Grubbs, Brendan, University of Southern California, Los Angeles, California, United States
  • De Filippo, Roger E., Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Perin, Laura, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Sedrakyan, Sargis, Children's Hospital of Los Angeles, Los Angeles, California, United States
Background

Glomerular endothelial dysfunction plays a key role in the development of chronic kidney disease (CKD), but its impact on Alport syndrome (AS, characterized by mutations in collagen IVα3α4α5) is unknown. We have previously shown that glomerular endothelial cells (GEC) are damaged in AS mice, manifested by enlarged fenestrations and alteration of the glycocalix in the early stage of disease. In the present study we report the early transcriptional changes in AS GEC as an indication of endothelial dysfunction and a contributing factor to Alport progression.

Methods

We generated endothelial tdTomato reporter AS mice and isolated GEC at 4 month of age by FACS. We studied tdT specificity in GEC by flow cytometry, WB, and by multiphoton and confocal microscopy, and their transcriptome by RNA-seq analysis. Data were analyzed and AS-GEC were compared to WT-GEC in terms of their morphology and differential gene expression. Tissue samples from patients with AS were used to confirm out findings from mice to that of in human by immunohistochemistry.

Results

Comparative transcriptomics showed high enrichment of differentially expressed genes associated with cellular metabolism, with lipid metabolism being among the top five most highly enriched biological processes in GEC. In particular, genes associated with fatty acid uptake, synthesis and oxidation were significantly downregulated. Among the differentially regulated genes, PGC-1α, which acts as a master regulator of cellular metabolism, was the most highly downregulated. Downstream of PGC-1α, genes associated with fatty acid transport, (CD36, FATP-1, FATP-2, Fabp3), fatty acid synthesis (fatty acid synthase), fatty acid oxidation (Acox1, Bdh2, Eci3, Abcd2), and antioxidant enzymatic scavenger proteins (Gpx3, Gpx6, Gsta3, sod2) were also downregulated. We observed similar findings in human biopsy samples from AS patients by histology.

Conclusion

In sum, we report for the first time a lipid metabolic dysfunction in Alport glomerular endothelial cells. Therefore, better understanding of the functional role of the glomerular endothelium in AS could lead to the development of targeted new therapies for the treatment of this and other forms of CKD.

Funding

  • Private Foundation Support