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Abstract: TH-PO989

Podocyte-Specific Knockdown of PAI-1 Protects Against Podocyte Injury

Session Information

Category: Pathology and Lab Medicine

  • 1501 Pathology and Lab Medicine: Basic

Authors

  • Zhong, Jianyong, Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Matsusaka, Taiji, Tokai University School of Medicine, Isehara, Kanagawa, Japan
  • Yang, Haichun, Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Fogo, Agnes B., Vanderbilt University Medical Center, Nashville, Tennessee, United States
Background

Plasminogen activator inhibitor-1 (PAI-1) is upregulated in a variety of fibrotic kidney diseases. Our previous study showed systemic knockout of PAI-1 protects against development of glomerulosclerosis (GS) and podocyte injury in both models of primary podocyte injury and secondary FSGS in the 5/6 nephrectomy model. In this study, we investigated whether knockdown (KD) of PAI-1 only in podocytes can protect against podocyte and glomerular injury.

Methods

We generated inducible podocyte PAI-1 knockdown mice (PAI-1 KD, PAI-1floxed/ rtTA/podocin Cre+) and wild type control (WT, PAI-1floxed/ rtTA/podocin Cre-). A model of secondary mild hypertensive podocyte injury was induced by high salt+uninephrectomy (uNX)+AngII. We also mated PAI-1 KD mice with Nphs1-hCD25 mice (Nep25), which express human CD25 just in podocytes, and develop primary podocyte injury when injected with immunotoxin (LMB2). Podocyte injury and GS were compared in these two models. In vitro, we cultured primary podocytes from these WT and PAI-1 KD mice and exposed cells to AngII or LMB2, respectively.

Results

In vitro primary cultured podocytes showed reduced PAI-1 after doxycycline induction. In vivo, double staining confirmed reduced PAI-1 in podocytes in both models, but increased PAI-1 expression in endothelial cells and mesangial cells. In the Nep25 model, PAI-1 KD in podocytes resulted in less albuminuria (ACR) and GS with more differentiated podocytes than WT (WT-1+ cell density, PAI-KD 27.4±1.8 vs. WT 21.8±1.9x10-4/μm2). In the high salt+uNX+AngII model, although podocytes expressed less desmin (PAI-KD 0.027±0.008 vs. WT 0.051±0.008), a marker of podocyte injury, ACR and mesangial expansion were similar in PAI-1 KD and WT. In vitro, knockdown of PAI-1 induced more podocyte proliferation, adhesion and migration in both LMB2 and AngII injury models, with less CTGF and desmin expression vs WT. ILK was reduced in PAI-1 KD vs WT only in the AngII model.

Conclusion

Knockdown of PAI-1 only in podocytes protected against primary podocyte injury and GS, while there was less effect on GS if the injury involved multiple cells, as seen in the AngII model. Our data further suggest that PAI-1 upregulation of ILK may be one mechanism related to podocyte injury.

Funding

  • NIDDK Support