Abstract: TH-PO338

TWEAK and RIPK1 Mediate Secondary Cell Death During AKI

Session Information

Category: Acute Kidney Injury

  • 002 AKI: Repair and Regeneration

Authors

  • Martin-Sanchez, Diego, IIS-Fundación Jiménez Díaz, Madrid, Spain
  • Fontecha, Miguel, IIS-Fundación Jiménez Díaz, Madrid, Spain
  • Carrasco, Susana, IIS-Fundación Jiménez Díaz, Madrid, Spain
  • Sanchez-Nino, Maria Dolores, IIS-Fundación Jiménez Díaz, Madrid, Spain
  • Ruiz-Ortega, Marta, Universidad Autonoma, Madrid, Spain
  • Egido, Jesus, IIS-Fundación Jiménez Díaz, Madrid, Spain
  • Linkermann, Andreas, University Hospital Carl Gustav Carus Dresden, Dresden, Germany
  • Ortiz, Alberto, IIS-Fundación Jiménez Díaz, Madrid, Spain
  • Sanz, Ana Belen, IIS-Fundación Jiménez Díaz, Madrid, Spain
Background

TWEAK is a member of the TNF superfamily that, in a proinflammatory environment, induces renal tubular cell death. TWEAK, TNFα and IFNγ (TTI)-induced cell death has features of apoptosis and is associated to activation of caspases and mitochondrial stress. However, inhibition of caspases with zVAD in vitro and in vivo was not protective. Recently, it was reported that ferroptosis plays a key role in the initial wave of tubular cell death in AKI, and beyond cell death, it mediates upregulation of inflammatory molecules, as Fn14, and of necroptosis proteins.
We hypothesized that TWEAK in collaboration with RIPK1 could contribute to a secondary wave of inflammation-related cell death during AKI.

Methods

Fn14 knockout (Fn14-KO), RIPK3 KO mice or wild type (WT) mice received a single i.p. injection of folic acid. Some WT mice were pretreated with Nec-1. In vitro studies were performed in murine proximal tubular MCT cells.

Results

Fn14-KO mice were protected from AKI, as assessed by serum BUN and creatinine levels, and reduced cell death, assessed by TUNEL, at 72h, while, at 24 hours there is not protection. This suggests that TWEAK contributes to secondary cell death in AKI. In cultured cells, TTI induces caspase activation, but zVAD changed the mode of cell death from apoptosis to necroptosis. The RIPK1 inhibitor Nec-1 prevented both cell death induced by TTI and by TTI+zVAD (TTI/Z), suggesting that RIPK1 is implicated in both apoptosis and necroptosis. Specifically, Nec-1 prevented features of apoptosis as caspase activation. By contrast, RIPK3 and MLKL siRNA only prevented TTI/Z-induced cell death suggesting that this process is mediated by necroptosis. Both Nec-1 and RIPK3 deficiency protected from AKI at 96h, showing the implication of necroptosis. This suggests that TWEAK/RIPK1 may mediate the secondary wave of cell death during AKI.

Conclusion

TWEAK in association with RIPK1, plays a key role in secondary, inflammation-related cell death in AKI. In vitro experiment showed that TTI-induced cell death has features of apoptosis but is dependent on the kinase activity of RIPK1. By contrast, caspase inhibition changed the mode of cell death to necroptosis. These results open a new therapeutic window to treatment of AKI once it has been established.