Kidney Week

Abstract: SA-PO313

The Molecular Mechanism of Action of AT2R Agonist Compound 21 (C21) on Ameliorating Murine FSGS

Session Information

• Cellular Crosstalk in Glomerular Diseases - II
  October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1201 Glomerular Diseases: Fibrosis and Extracellular Matrix

Authors

• Liao, Min-Chun, CRCHUM, Universite de Montreal, Montreal, Quebec, Canada

Min-Chun Liao,

• Chang, Shiao-Ying, CRCHUM, Universite de Montreal, Montreal, Quebec, Canada

Shiao-Ying Chang,

• Lo, Chao-Sheng, CRCHUM, Universite de Montreal, Montreal, Quebec, Canada

Chao-Sheng Lo,

• Chenier, Isabelle, CRCHUM, Universite de Montreal, Montreal, Quebec, Canada

Isabelle Chenier,

• Ingelfinger, Julie R., The New England Journal of Medicine, Boston, Massachusetts, United States

Julie R. Ingelfinger,

• Chan, John S.D., CRCHUM, Universite de Montreal, Montreal, Quebec, Canada

John S.D. Chan,

• Zhang, Shao-Ling, CRCHUM, Universite de Montreal, Montreal, Quebec, Canada

Shao-Ling Zhang,

Background

We previously reported (J Pathology 2017) that angiotensin II type 2 receptor (AT₂R) deficiency is associated with podocyte loss and podocyte transition from normal morphology to apoptotic and/or fibrotic-like phenotype via hedgehog interacting protein (Hhip) gene expression. Here, we examined whether the administration of AT₂R agonist Compound 21 (C21) would ameliorate murine FSGS and investigated the underlying mechanisms both in vivo and in vitro.

Methods

FSGS was induced by a single intravenous injection of doxorubicin (18 mg/kg, body weight, in saline) in both male wild type (WT) and AT₂R knockout (KO) mice at 8 weeks of age. Mice were euthanized 4 weeks after doxorubicin injection. Five subgroups of mice including WT [Control (WT-Con), WT-FSGS, FSGS treated with C21 (0.3 mg/kg/day, intraperitoneal (i.p.) (WT-FSGS-C21] and AT₂R KO mice [Control (KO-Con) and KO-FSGS] were studied. Physiological parameters, renal morphology/function analysis and molecular analysis in glomeruli were carried out; in vitro studies were done in a mouse podocyte cell line (mPODs).

Results

FSGS was far more severe in AT₂RKO mice as compared to WT-FSGS mice, evidences by profound glomerulosclerosis on Periodic Acid Schiff and Masson trichrome staining, increased podocyte loss (synaptopodin- and p57-immunofluorescence (IF) staining) and more proteinuria (urinary albumin/creatinine ratio measurement and urinary Coomassie blue staining), together underscoring the key role of AT₂R in FSGS-related podocyte-glomerulopathy. As compared with WT-Con, WT animals with FSGS had high numbers of parietal epithelial cells (PECs), which are paired homeobox 2 (Pax2) positive cells, but fewer podocytes (IF-p57 positive and IF-Pax2 negative cells). Intriguingly, C21 administration (WT-FSGS-C21) ameliorated the features of FSGS (proteinuria, renal morphology/function) via inhibition of glomerular Hhip expression. In vitro, increased Hhip and Pax2 gene expression with transient transfection of respective cDNAs promoted apoptotic and/or fibrotic-like phenotype shift in podocytes.

Conclusion

The glomerular AT₂R-Pax2-Hhip axis appears to be involved in the transition of podocytes to PECs; we speculate such transition occurs through AT₂R-Pax2-Hhip modulation of PEC-related profibrotic effects and subsequent podocyte loss/sclerosis in FSGS

Funding

• Government Support - Non-U.S.