Pharmacological Nephroprotection in a Novel Mouse Model of Hereditary Nephrotic Syndrome Ivana Simic, Mansoureh Tabatabaeifar, Helga Denc, Tanja Wlodkowski, Geraldine Mollet, Corinne Antignac, Franz Schaefer Division of Pediatric Nephrology, University of Heidelberg Department of Human Genetics, Hopital Necker, Paris 25 th European Congress of Pathology, Lisbon, 31 August – 4 September 2013

The NPHS2 Gene and Hereditary Nephrotic Syndrome Mutations in the NPHS2 gene, encoding podocin, cause autosomal recessive steroid-resistant nephrotic syndrome R138Q, the most common podocin mutation in Europeans, causes early disease onset and rapid progression to end-stage renal disease Recently, we generated and characterized an inducible knock- in mouse carrying the R140Q podocin mutation, the murine analogue of the most common human mutation R138Q N-term C-term R138Q

Creation of a Conditional Knock-in Mouse Model of R140Q Mutation Cre Nphs2 R140Q/+ Nphs2 lox2/lox2 Cre +/+ Nphs2 lox2/R140Q Cre + Nphs2 R140Q/- X Tamoxifen induction Bl6

Prophylactic RAS Blockade in a Conditional Knock-in Mouse Model of R140Q Mutation Tamoxifen-induced mice received 10 mg/kg/day of: ACE inhibitor Ramipril (R) AT1 receptor blocker Candesartan (C) the combination of Ramipril and Candesartan (R+C) non-RAS antihypertensive amlodipine (A) Control groups: Tamoxifen induction (sick controls) Vehicle injections (healthy controls)

Blood Pressure Effect of RAS Antagonists vs. Amlodipine *** ** * * p<0.05; ** p<0.01; *** p<0.001

Markedly Attenuated Proteinuria in Podocin R140Q Knock-In Mice Treated with RAS Antagonists

Normoalbuminemia in Podocin R140Q Knock-In Mice Treated with RAS Antagonists * p<0.05; ** p<0.01; *** p<0.0001

Reduced Plasma Creatinine Levels in All Treated Animals

Subtotal Loss of Podocin Protein in All Induced Animals Irrespective of Pharmacological Treatment Podocin GAPDH 37 kDa 4 WKS Control R C R+C A

The Loss of Podocin Signal at Immunofluorescence Analysis healthy untreated R+C Amlodipine

Preserved Podocin mRNA Expression in All Induced Animals * * p>0.05 comparing to both sick untreated and healthy animals

Attenuated Glomerulosclerosis in Animals Treated with RAS Antagonists **** ***** * * p>0.05; ** p<0.05; *** p<0.01; **** p<0.001 A. B. PAS staining of renal tissue in induced animals: A. Untreated (notable GS); B. Mice treated with R+C.

Insignificantly Attenuated Tubulointerstitial Fibrosis in Animals Treated with RAS Antagonists p>0.05 Sirius-Red-staining: A. Untreated animals; B. Mice treated with R+C. A. B.

Improved Podocyte Survival in Animals Treated with RAS Antagonists * ** *** * p<0.05; ** p<0.01; *** p<0.001 A. B. WT1 immunostaining of glomeruli of induced mice: A. Untreated (reduced podocyte number); B. Treated with R+C.

Summary RAS antagonists markedly attenuate proteinuria in mice hemizygous for podocin R140Q mutation After 4 weeks, mice receiving R+C were normo-albuminemic and serum creatinine was increased less than in untreated or animals treated with Amlodipine Reduced glomerulosclerosis and better podocyte survival in animals treated with RAS antagonists RAS blockade provides effective pharmacological nephroprotection in this hereditary podocytopathy model

Dr. Ivana Simic Dr. Mansoureh Tabatabaeifar Tanja Wlodkowski Dr. Helga Denc Prof. Dr. Franz Schaefer Hopital Necker, France Dr. Geraldine Mollet Prof. Dr. Corinne Antignac