Abstract: SA-PO1173
Klotho Mitigates Indoxyl Sulfate-Induced Oxidative Stress through Modulation of the AKT/Nrf2 Pathway
Session Information
- CKD: Mechanisms - 3
October 26, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 2303 CKD (Non-Dialysis): Mechanisms
Authors
- Sun, Chien Yao, National Cheng Kung University Hospital, Tainan, Tainan, Taiwan
- Chao, Chia-Ter, National Taiwan University Hospital, Taipei, Taiwan
- Chang, Yu Tzu, National Cheng Kung University Hospital, Tainan, Tainan, Taiwan
Background
Chronic kidney disease (CKD) is a progressive condition with significant global prevalence. The uremic toxin indoxyl sulfate (IS) induces tubulotoxicity and oxidative stress in CKD patients. It has been shown that IS downregulates the expression of the anti-aging protein klotho in proximal tubule cells and kidneys. The detailed mechanism of reduced klotho's role in nephropathy and oxidative stress is unclear.
Methods
We treated renal proximal tubule epithelial cells (HK-2 cells) with 500μM IS to induce oxidative stress. Antioxidant gene expression was studied by real-time PCR, and ROS levels were investigated by DCF-DA.
Results
Our results showed that the mRNA expression levels of HO-1 and NQO1 were suppressed in IS-treated cells, but administration of klotho counteracted this effect. Blocking AKT/Nrf2 signaling with an AKT inhibitor (LY2780301) or silencing Nrf2 impeded klotho's rescue effect on HO-1 and NQO1 expression, suggesting that IS inhibits HO-1 and NQO1 via the klotho/AKT/Nrf2 axis. We also examined superoxide dismutase (SOD) expression and found that IS treatment reduced SOD levels, which were restored by recombinant klotho. Inhibition of AKT/Nrf2 signaling negated Klotho's beneficial effect on SOD concentration. IS-stimulated cells showed elevated ROS formation, while recombinant klotho hindered this upregulation. Suppression of AKT/Nrf2 signaling restrained Klotho's protective effect against IS-induced ROS production.
Conclusion
Our findings suggest that IS increases oxidative stress in HK-2 cells by elevating ROS and inhibiting antioxidant capacity, as evidenced by lower expression of HO-1, NQO1, and SOD via the Klotho/AKT/Nrf2 signaling pathway.
Klotho reduces IS-increased oxidative stress.
Funding
- Other NIH Support