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Kidney Week

Abstract: TH-PO773

Dual Deletion of Guanylyl Cyclase-A and p38 Mitogen-Activated Protein Kinase (MAPK) in Podocytes with Aldosterone Administration Causes Glomerular Intracapillary Thrombi

Session Information

Category: Glomerular Diseases

  • 1403 Podocyte Biology

Authors

  • Sugioka, Sayaka, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Yamada, Hiroyuki, Department of Primary Care & Emergency Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Ishii, Akira, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Kato, Yukiko, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Yamada, Ryo, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Mori, Keita P., Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Ohno, Shoko, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Handa, Takaya, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Ikushima, Akie, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Ishimura, Takuya, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Matsusaka, Taiji, Department of Molecular Life Sciences, Tokai University School of Medicine, Isehara, Japan
  • Yanagita, Motoko, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
  • Yokoi, Hideki, Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
Background

Previously, we demonstrated that podocyte-specific guanylyl cyclase-A (GC-A; natriuretic peptide receptor 1; NPR1) conditional KO (pod-GC-A cKO) mice with aldosterone exhibit podocyte injury, and that pharmacological inhibition of p38 MAPK ameliorates it. However, the effects of genetic deletion of p38 MAPK in podocytes have been unknown.

Methods

We generated podocyte-specific p38 MAPK and GC-A double cKO (pod-double cKO) mice, and treated them with aldosterone and high salt without nephrectomy (B-ALDO). Next, we focused on PAI-1 (SERPINE1) and administered PAI-1 neutralizing antibody to pod-double cKO mice. In vitro, we examined human podocytes in which p38 MAPK was deleted by CRISPR/Cas9 system and GC-A was suppressed by siRNA. Then, we cultured human p38 MAPK-null podocytes transfected with si-NPR1 in the upper layer and wild-type glomerular endothelial cells (GE) in the lower layer, with PAI-1 inhibitor in the transwells.

Results

Unexpectedly, B-ALDO-treated pod-double cKO mice resulted in elevation of serum Cr, massive albuminuria and severe foot process effacement in addition to intracapillary fibrin thrombi indicating endothelial damage. PAI-1 was increased in podocytes and treatment with PAI-1 neutralizing antibody ameliorated intracapillary thrombus formation in B-ALDO-treated pod-double cKO mice. In vitro, knockout of p38 MAPK and suppression of GC-A in human cultured podocytes upregulated SERPINE1, TGFB1, and FN1. Deletion of p38 MAPK and inhibition of GC-A in podocytes in the upper layer upregulated TGFB1 in the GE in the lower layer, indicating that some humoral factors derived from podocytes could work as cell-to-cell mediators. The treatment with PAI-1 inhibitor decreased TGFB1 in both podocytes and GE.

Conclusion

Podocyte-specific deletion of p38 MAPK and GC-A exacerbated glomerular endothelial cell injury as well as podocyte damage which was ameliorated by PAI-1 neutralizing antibody. PAI-1 in podocytes is one factor that disrupts the podocyte-endothelial crosstalk, suggesting that p38 MAPK and GC-A play indispensable roles in podocytes.