Abstract: FR-PO695
Therapeutic Blockade of the SLIT/ROBO Signaling Pathway Alleviates Podocytopathy Defects in Integrin-Linked Kinase Podocyte-Specific Knockout Mice
Session Information
- Glomerular Diseases: Podocyte Biology - I
November 04, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1304 Glomerular Diseases: Podocyte Biology
Authors
- Kumar, Sudhir, Boston University, Boston, Massachusetts, United States
- Fan, Xueping, Boston University, Boston, Massachusetts, United States
- Zaltz, Emily, Boston University, Boston, Massachusetts, United States
- Chen, Hui, Boston Medical Center, Boston, Massachusetts, United States
- Henderson, Joel M., Boston University, Boston, Massachusetts, United States
- Salant, David J., Boston University, Boston, Massachusetts, United States
- Yang, Hongying, Pfizer Inc, Cambridge, Massachusetts, United States
- Berasi, Stephen, Pfizer Inc, Cambridge, Massachusetts, United States
- Lu, Weining, Boston University, Boston, Massachusetts, United States
Background
The SLIT/ROBO signaling pathway negatively regulates podocyte adhesion and actin polymerization. Podocyte-specific deletion of integrin-linked kinase (ILK) in mice (ILK cKO) causes a podocytopathy reflecting FSGS with severe proteinuria, podocyte loss, and renal failure. We hypothesized that therapeutically blocking the SLIT/ROBO pathway with a ROBO2-IgG-Fc fusion protein would improve the podocytopathy phenotype in adult ILK cKO mice.
Methods
Seven-week-old ILK cKO homozygous mice were generated and treated with the ROBO2-IgG-Fc fusion protein or control IgG at 25 mg/kg every 2-3 days for 16 weeks. The survival probability of ILK cKO mice was calculated using the Kaplan Meier estimator. Urine samples were collected every two days to measure the urine albumin-to-creatinine ratio (UACR). Renal function (BUN measurement), kidney histology (PAS staining), podocyte number (P57 staining), podocyte foot process width (FPW), and slit diaphragm (SD) density of ILK cKO mice were assessed after three weeks of the treatment.
Results
Median survival was significantly longer in ROBO2-IgG-Fc treated than control IgG treated ILK cKO mice (105 days versus 52 days). After 3-weeks of treatment, significant mean UACR reductions were observed on day 18 (46%) and day 21 (50%) in ROBO2-IgG-Fc treated ILK cKO mice compared to control IgG treated mice. In addition, BUN was considerably lower in ILK cKO mice treated with the ROBO2-IgG-Fc (88 mg/dL) than the control IgG (124 mg/dL). Finally, podocyte loss, podocyte FPW, SD density, and renal tubular injury in ILK cKO mice were significantly improved by the ROBO2- IgG-Fc treatment compared to control IgG.
Conclusion
Therapeutic inhibition of the SLIT/ROBO signaling pathway ameliorates the podocytopathy phenotype and significantly extends the life span of adult ILK podocyte-specific knockout mice via preventing podocyte loss, reducing albuminuria, and improving renal function. Our studies provide additional confidence in rationale for blocking the ROBO/SLIT signaling pathway for treating podocytopathies and proteinuric kidney diseases. A phase 2 (NCT03448692) clinical trial testing the efficacy of a ROBO2-Fc fusion protein (PF-06730512) in FSGS patients is ongoing.
Funding
- NIDDK Support –