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Abstract: FR-PO987

Deletion of the Non-Canonical NOTCH Ligand DLK1 Promotes an Overactivation of the NOTCH Signaling Pathway and the Th17 Immune Response in the Unilateral Ureteral Obstruction Model

Session Information

Category: Pathology and Lab Medicine

  • 1601 Pathology and Lab Medicine: Basic

Authors

  • Marquez-Exposito, Laura, Universidad Autónoma de Madrid, Madrid, Spain
  • Rodrigues díez, Raúl R., Universidad Autónoma de Madrid, Madrid, Spain
  • Rayego-Mateos, Sandra, Universidad Autónoma de Madrid, Madrid, Spain
  • Fierro-Fernández, Marta, Centro de Biología Molecular Severo Ochoa, Madrid, Spain
  • Rodrigues-Diez, Raquel, Universidad Autónoma de Madrid, Madrid, Spain
  • Orejudo del río, Macarena, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, Madrid, Spain
  • Laborda, Jorge, Universidad de Castilla-La Mancha, Albacete, Spain
  • Mezzano, Sergio A., Universidad Austral de Chile, Valdivia, Chile
  • Lamas, Santiago, Centro de Biología Molecular Severo Ochoa, Madrid, Spain
  • Lavoz, Carolina, Universidad Austral de Chile, Valdivia, Chile
  • Ruiz-Ortega, Marta, Universidad Austral de Chile, Valdivia, Chile
Background

The NOTCH signaling pathway is activated in embryonic development, silenced in adult tissues, and reactivated in human kidney diseases. The non-canonical ligand DLK1 has been described as a Notch inhibitor in Drosophila and in mammal cells, but there are no data in renal injury. In renal pathologies, Th17 response has been involved in immune and nonimmune diseases, including diabetic nephropathy.

Methods

129/SvJ mice with an embrionary deletion in the Dlk1 gene were used. The Unilateral Ureteral Obstruction (UUO) model was performed in both the transgenic and the WT mice, and data studied at 2, 5, 10 and 14 days after the injury. C57BL/6 mice were treated daily with 0.1 mg/day of the γ-secretase inhibitor DAPT, starting one day before the UUO procedure and sacrificing the animals 5 days after.

Results

Non-canonical ligands DLK1 and DLK2 were studied at each point, showing increased gene expression levels from day 5 to 14 in the WT animals. The inflammatory infiltrate was scored by PAS staining in the obstructed kidneys and it was significantly increased in the Dlk1-null mice vs WT from 5 days and continued at 10 and 14 days. Remarkably, at 14 days these knockout obstructed kidneys showed a huge inflammatory infiltrate as aggregates, not found in the WT animals. These inflammatory aggregates were positive for the NICD, as well as some tubules, demonstrating that the Dlk1-null mice have an overactivation of the NOTCH pathway in the obstructed kidneys. They were also associated to a significant increase of CD3+, CD4+, F4/80+ infiltrating cells and neutrophils. At 14 days, the increase of the Th17 response in the Dlk1-null obstructed kidneys was very remarkable, as shown by the elevation of the transcription factors RORγt and STAT3 and the effector cytokine, IL17A. These factors were also increased at 5 days in the C57BL/6 mice and clearly diminished with the tratment of the γ-secretase inhibitor DAPT.

Conclusion

Deletion of DLK1 overactivates the Notch pathway in the UUO model, and this triggers an increase in the inflammation of the tissue as well as an induction of the Th17 response. Therefore, DLK1 can be suggested as a Notch inhibitor in this context.

Funding

  • Government Support - Non-U.S.