Kidney Week

Abstract: SA-PO292

Deletion of Angiotensinogen in Renal Tubules Attenuates Tubular Senescence in Diabetic Kidney Disease

Session Information

• Diabetic Kidney Disease: Basic - 2
  October 26, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Diabetic Kidney Disease

• 701 Diabetic Kidney Disease: Basic

Authors

• Yang, Wenxia, Centre de Recherche du Centre Hospitalier de l'Universite de Montreal, Montreal, Quebec, Canada

Wenxia Yang, PhD

• Su, Ke, Centre de Recherche du Centre Hospitalier de l'Universite de Montreal, Montreal, Quebec, Canada

Ke Su, PhD

• Liao, Min-Chun, Centre de Recherche du Centre Hospitalier de l'Universite de Montreal, Montreal, Quebec, Canada

Min-Chun Liao, PhD

• Peng, Junzheng, Centre de Recherche du Centre Hospitalier de l'Universite de Montreal, Montreal, Quebec, Canada

Junzheng Peng, MD

• Miyata, Kana, Saint Louis University, St Louis, Missouri, United States

Kana Miyata, MD

• Filep, Janos G., Hopital Maisonneuve-Rosemont, Montreal, Quebec, Canada

Janos G. Filep, MD

• Ingelfinger, Julie R., Massachusetts General Hospital, Boston, Massachusetts, United States

Julie R. Ingelfinger, MD

• Zhang, Shao-Ling, Centre de Recherche du Centre Hospitalier de l'Universite de Montreal, Montreal, Quebec, Canada

Shao-Ling Zhang, PhD

• Chan, John S.D., Centre de Recherche du Centre Hospitalier de l'Universite de Montreal, Montreal, Quebec, Canada

John S.D. Chan, PhD

Background

We reported previously that renal tubule (RT)-specific angiotensinogen (Agt) deletion attenuates kidney injury in type 1 diabetic Akita mice by reducing glomerular hyperfiltration, tubular injury score, urinary albumin-creatinine ratio and SGLT2 expression in renal proximal tubules (RPTs) (ASN’23, SA-PO423). Angiotensin II (Ang II) elicits reactive oxygen species (ROS), triggering oxidative DNA damage, cellular senescence and senescence-associated secretory phenotype (SASP). This study aimed to investigate whether RT-Agt deletion attenuates kidney injury by mitigating tubular senescence in Akita mice.

Methods

Diabetic Akita mice with RT-specific deletion of Agt (Akita RT-Agt KO) were generated by crossbreeding Pax8-Cre mice with Agt-floxed Akita mice. Male non-diabetic control, RT-Agt KO, Akita, and Akita RT-Agt KO mice were studied at 20 weeks of age. In vitro, Madin-Darby Canine Kidney (MDCK, a distal tubule (DT) cell line) cells and HK-2 (human immortalized proximal tubule cell line) cells were used.

Results

Akita mice exhibited increased urinary AGT and Ang II, as well as senescence-associated β-galactosidase positive renal tubules vs. control and RT-Agt^- KO mice and these were normalized in Akita RT-Agt KO mice. Notably, immunofluorescent staining of Ang II was increased and colocalized with the DT marker (lycopersicon esculentum lectin (LEL)) in Akita mice, along with elevated markers of oxidative DNA damage (8-Hydroxy-2’-deoxyguanosine (8-OHdG)) and senescence marker (p16) staining. These changes were normalized in Akita RT-Agt KO mice. Moreover, SASP components including CCL2, CXCL1, and TNF-α mRNA were upregulated in Akita mouse kidneys and attenuated in Akita RT-Agt KO mice. In vitro, Ang II-induced senescence in MDCK, which was attenuated by losartan (an AT1R blocker) or NAC (N-acetyl L-cysteine, an ROS inhibitor). Finally, addition of senescent MDCK-derived conditioned medium to HK-2 culture facilitated the epithelial-to-mesenchymal transition, which was reversed by losartan or NAC treatment.

Conclusion

RT-derived Agt/Ang II triggers cellular senescence in renal tubules via ROS-mediated DNA damage and the p16 pathway, leading to SASP and increased tubular injury in Akita mice. These results highlight the importance of inhibiting intrarenal RAS to prevent DKD progression.

Funding

• Government Support – Non-U.S.