Abstract: FR-PO845
Elucidating Lupus Nephritis (LN) Pathogenesis by Evaluating the Intersection between Glycomics and Metabolism
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
- Bhargava, Rhea, Tulane University, New Orleans, Louisiana, United States
- Upadhyay, Rohit, Tulane University, New Orleans, Louisiana, United States
- Chen, Jing, Tulane University, New Orleans, Louisiana, United States
- Katakam, Prasad V., Tulane University, New Orleans, Louisiana, United States
- Tsokos, George C., Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
Background
Lupus nephritis (LN) is the most devastating complication of systemic lupus erythematosus (SLE). Patients with LN have higher mortality than SLE patients without LN. The ability to accurately identify SLE patients destined to develop LN could shift the current management to prevention. Podocyte injury is an early event in LN and occurs by exposure to aberrantly glycosylated IgG. Here, we demonstrate that in LN, aberrantly glycosylated IgG can reprogram podocyte metabolism leading to podocyte injury.
Methods
Human podocytes were exposed to IgG with and without treatment with PNGase from healthy subjects, SLE, LN and LN-remission patients. ATP rate, glycolytic rate assay and untargeted metabolomics were performed. Podocyte injury was evaluated by scratch assay, phalloidin staining and nephrin expression. Urine podocytes were isolated and targets were validated by droplet digital PCR in urine and urine cells.
Results
Glycolysis was the primary process for energy production in podocytes. Podocytes exposed to LN IgG had a lower rate of glycolysis compared to deglycosylated and healthy IgG. Untargeted intracellular metabolomics revealed 332 metabolites across the 9 samples. A total of 56 metabolites were significantly different between cells treated with LN vs deglycosylated LN IgG. Metabolite set enrichment analysis (MSEA) was carried out in reference to the database of pathway-associated metabolite sets (SMPDB). Glycolysis was the most enriched pathway with 5 hit compounds (pyruvic acid, phosphoenolpyruvic acid, 2-phosoglycerate, 3 phosphoglycerate , fructose 1,6 biphosphate) that were differentially regulated. The fold enrichment for the pathway was 8.4. These metabolites were validated in urine/urine cells isolated from 15 SLE patients with and without LN. Urine pyruvate and PKM levels in cells were found to differentiate active LN from controls.
Conclusion
To our knowledge this is the first study to demonstrate a link between glycoproteins regulating cell metabolism. These data plausibly suggest that LN-derived IgG leads to significant podocyte injury by reducing their ability to compensate for the increased energy supply required for repair and maintenance of their shape and structure, leaving them vulnerable to any stress and possibly accelerating LN.
Funding
- Other NIH Support