Abstract: SA-PO583
Molecular Mechanisms of Renal Fibrosis in Alport Syndrome
Session Information
- Glomerular Diseases: Fibrosis, Extracellular Matrix
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1201 Glomerular Diseases: Fibrosis and Extracellular Matrix
Authors
- Minor, Kenneth, Plato BioPharma, Inc., Westminster, Colorado, United States
- Joly, Kristin M., Plato BioPharma, Inc., Westminster, Colorado, United States
- Schwabauer, Denise L., Plato BioPharma, Inc., Westminster, Colorado, United States
- Plato, Craig F., Plato BioPharma, Inc., Westminster, Colorado, United States
Background
Alport Syndrome is a rare hereditary disease caused by mutations in glomerular basement membrane (GBM) type IV collagen and characterized by progressive renal fibrosis and early onset ESRD. Collagen IV dysregulation and loss of GBM integrity allows passage of albumin to the tubular lumen causing injury and ultimately tubulointerstitial fibrosis in advanced Alport Syndrome. To date, the signaling pathways and molecular targets in albuminuria-induced fibrosis in Alport Syndrome have not been elucidated.
Methods
We evaluated the kinetics and potential mechanisms of renal fibrosis in Col4a3 knock out (Col4a3KO) mice, a model of autosomal recessive Alport Syndrome compared to age-matched Wild Type (WT) controls. Approximately equal numbers of male and female Mice were studied from 5–10 wks age to evaluate the renal fibrotic response to progressive albuminuria. At 6, 8 and 10 wks, representative cohorts of mice were euthanized and kidneys were harvested for biochemical and histological analyses. mRNA expression was analyzed using a Quantigene pro-inflammatory and fibrotic gene multiplex (MCP-1, CTGF, TGF-β1, α-SMA, FN1 and Collagens 1a1 and 3a1). Renal cortical hydroxyproline (OH-P) content and Collagen Volume Fraction (CVF) via Picrosirius Red (PSR) histology were also evaluated. Renal cortical lysates were evaluated for TGF-β1 content and phospho- p38, JNK and Erk to elucidate potential pathways in albuminuria-induced fibrosis.
Results
Col4a3KO had age-dependent polyuria and fulminant albuminuria (5 wks: 360-fold; 10 wks: ~2,500-fold) compared to WT. Renal cortical OH-P content was not increased by 6 wks but increased thereafter. Associated with progressive albuminuria, CVF was age-dependently increased in Col4a3KO (8 wks: 10-fold; 10 wks: 25-fold). Although pro-inflammatory and fibrotic mRNA species were increased by 6 wks in Col4a3KO, peak expression occurred at 8 wks, in advance of peak fibrosis. Renal cortical TGF-β1 content was age-dependently increased while pJNK and pERK peaked at 8–10 wks.
Conclusion
This study demonstrates albuminuria precedes renal fibrosis in the Col4a3KO model of Alport Syndrome and identifies potential mechanisms related to disease progression. These results enable future investigations of inflammatory and stress-signaling pathways in Alport Syndrome, and evaluation of novel therapies to attenuate albuminuria-induced renal fibrosis.
Funding
- Commercial Support – Plato BioPharma, Inc.