Kidney Week

Abstract: FR-OR066

Exon Skipping Therapy for COL4A5 Gene Truncating Variant Rescued Progression of Kidney Failure in X-Linked Alport Syndrome

Session Information

• Genetic Diseases and the Kidneys
  November 08, 2019 | Location: 144, Walter E. Washington Convention Center
  Abstract Time: 05:30 PM - 05:42 PM

Category: Genetic Diseases of the Kidneys

• 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

• Yamamura, Tomohiko, Kobe University Graduate School of Medicine, Kobe, Japan

Tomohiko Yamamura, MD, PhD



Tomohiko Yamamura received the M.D. degree from Chiba University, Japan, in 2009 and Ph.D. degree from Kobe University, Japan, in 2017. He became an assistant professor of Department of Pediatrics, Kobe University Graduate School of Medicine in 2016. He works as pediatric nephrologist and current research interests include analysis of genotype-phenotype correlation in genetic kidney diseases and development of new therapy for these diseases.

• Nozu, Kandai, Kobe University Graduate School of Medicine, Kobe, Japan

Kandai Nozu,

• Horinouchi, Tomoko, Kobe University Graduate School of Medicine, Kobe, Japan

Tomoko Horinouchi,

• Nagano, China, Kobe University Graduate School of Medicine, Kobe, Japan

China Nagano,

• Sakakibara, Nana, Kobe University Graduate School of Medicine, Kobe, Japan

Nana Sakakibara,

• Aoto, Yuya, Kobe University Graduate School of Medicine, Kobe, Japan

Yuya Aoto,

• Kamura, Misato, Kuamoto University, Kumamoto, Japan

Misato Kamura,

• Kai, Hirofumi, Kumamoto University, Kumamoto, Japan

Hirofumi Kai,

• Iijima, Kazumoto, Kobe University Graduate School of Medicine, Kobe, Japan

Kazumoto Iijima,

Background

X-linked Alport syndrome (XLAS) is a hereditary disease caused by mutations of COL4A5 gene. Affected male patients generally develop end-stage renal disease in early or middle adulthood and patients with truncating variants show severer phenotype than those with non-truncating variants. In recent years, exon skipping (ES) therapy, which induces truncating variants into non-truncating variants, has been applied clinically in muscular dystrophy, etc. Here we applied the ES therapy for XLAS model mice and evaluated clinicopathological findings.

Methods

We generated C57B/6 mice with nonsense mutation in Col4a5 gene exon 21 (R471X) using CRISPER/Cas9 technique and clinicopathological features of this model was confirmed as typical for XLAS. In addition, we determined the antisense sequence (ASO) showed highest ES effect for exon 21 and administrated percutaneously to this model mouse once or twice a week from 4 weeks to 20 weeks of age. The effectiveness was evaluated both clinically and pathologically at 21 weeks of age.

Results

With clinical parameters, urinary albumin creatinine ratio was remarkably suppressed in ASO-treated group (n=5) compared to saline-treated group (n=6). At 21 weeks of age, serum BUN and creatinine levels were remarkably low in ASO treated group compared to vehicle treated group. With pathological evaluation by electron microscope, although even ASO-treated mice show thin basement membrane, they did not show severe thickening with lamellation of GBM as shown in saline-treated group. With immunofluorescence, α5(IV) was completely negative in vehicle group, but it expressed clearly on tubular basement membrane and even on GBM although expression is not linear but partially on GBM. No clear side effect was recognized in the ASO-treated group.

Conclusion

It was clarified that the clinical-pathological findings of the XLAS model mouse was remarkably improved by ES therapy using ASO. ES therapy is expected to be an effective therapy for XLAS patients with truncating variants.

Funding

• Commercial Support – Daiichi Sankyo company, Zenyaku Kogyo company