Abstract: SA-OR61
Inhibition of Sphingosine-1-Phosphate Receptor 4 Improves Renal Outcomes in a Mouse Model of Alport Syndrome
Session Information
- Glomerular Diseases: All about Podocytes
October 26, 2024 | Location: Room 1, Convention Center
Abstract Time: 05:30 PM - 05:40 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Merscher, Sandra M., University of Miami Miller School of Medicine, Miami, Florida, United States
- Tolerico, Matthew, University of Miami Miller School of Medicine, Miami, Florida, United States
- Carrazco, Arianna, University of Miami Miller School of Medicine, Miami, Florida, United States
- Molina David, Judith T., University of Miami Miller School of Medicine, Miami, Florida, United States
- Mendez, Armando, University of Miami Miller School of Medicine, Miami, Florida, United States
- Fornoni, Alessia, University of Miami Miller School of Medicine, Miami, Florida, United States
Group or Team Name
- Peggy and Harold Katz Family Drug Discovery Center.
Background
Col4a3 knockout (KO) mice, a model of Alport Syndrome, develop glomerular disease associated with renal neutral lipid accumulation and progressive renal failure that can be partially prevented and treated by lipid-lowering agents. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid which was found to accumulate in patients with nephrotic syndrome carrying mutations in the gene coding for S1P lyase. S1P exerts its effects by interacting with one of its five G-protein coupled receptors (S1PR1-5). The role of S1P signaling in podocytes and its therapeutic potential in glomerular disease is not well understood.
Methods
S1P levels were measured in kidney cortices of 8-week-old mice by LC-MS and normalized to protein concentration. S1PR4 expression levels in kidney cortices and cell lysates were determined by Western blot and qRT-PCR analysis. In vitro, podocytes were treated with an S1PR4 antagonist (CYM50358) for 24 hours. Neutral lipid levels were quantified using an enzymatic assay. Lipid droplets were stained by Nile Red staining and imaged on Opera Phenix HCS system. Apoptosis was determined by ApoTox-Glo™ Assay (Promega). CYM50358 (10mg/kg) was administered to Col4a3 KO by intraperitoneal injection starting at 4 weeks of age and until sacrifice at 8 weeks of age. Plasma and urine samples were collected at baseline and time of sacrifice and used to determine albumin to creatinine ratio (ACR), blood urea nitrogen (BUN), and plasma creatinine. Mesangial expansion was evaluated through Periodic Acid Schiff (PAS) staining. Renal fibrosis was evaluated by Picro-Sirius Red staining.
Results
Kidney cortices from Col4a3 KO mice had increased levels of S1P, and S1PR4 expression. Immortalized podocytes isolated from Col4a3 KO mice showed increased S1PR4 expression, apoptosis, and neutral lipid accumulation in form of lipid droplets. Antagonism of S1PR4 resulted in a reduction of apoptosis and neutral lipids. Treatment of Col4a3 KO mice with a S1PR4 antagonist was sufficient to reduce ACRs, BUN, and plasma creatinine. Treated mice displayed reduced mesangial expansion and renal fibrosis.
Conclusion
Our results suggest that inhibition of S1PR4 may be beneficial in preventing glomerular disease progression in a mouse model of Alport Syndrome, possibly by reducing neutral lipid accumulation.
Funding
- NIDDK Support