Kidney Week

Abstract: FR-PO088

Nrf2 Deficiency Aggravates Folic Acid-Induced AKI Through Upregulation of Renal Ferroptosis in Mice

Session Information

• AKI: Tubules, Metabolism, New Models
  October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

• 103 AKI: Mechanisms

Authors

• Zhang, Shiwen, The Affiliated Shengjing Hospital of China Medical University, Shenyang, Liaoning, China

Shiwen Zhang,

• Luan, Junjun, The Affiliated Shengjing Hospital of China Medical University, Shenyang, Liaoning, China

Junjun Luan,

• Fu, Jingqi, School of Public Health, China Medical University, Shenyang, Liaoning, China

Jingqi Fu,

• Kong, Weiwei, The Affiliated Shengjing Hospital of China Medical University, Shenyang, Liaoning, China

Weiwei Kong,

• Wang, Yanqiu, The Affiliated Shengjing Hospital of China Medical University, Shenyang, Liaoning, China

Yanqiu Wang,

• Li, Detian, The Affiliated Shengjing Hospital of China Medical University, Shenyang, Liaoning, China

Detian Li,

• Pi, Jingbo, School of Public Health, China Medical University, Shenyang, Liaoning, China

Jingbo Pi,

• Zhou, Hua, The Affiliated Shengjing Hospital of China Medical University, Shenyang, Liaoning, China

Hua Zhou,

Background

The role of nuclear factor erythroid 2-related factor 2 (Nrf2) in folic acid (FA)-induced acute kidney injury (AKI) remains unstudied so far. Ferroptosis is demonstrated to be involved in FA-induced AKI. We aim to verify whether Nrf2 deletion aggravated FA-induced AKI in mice and to investigate the corresponding mechanism.

Methods

Male Nrf2^+/+ and Nrf2^−/−mice were injected FA (100 mg/kg) intravenously to induce AKI. NaHCO3 was used as the vehicle. AKI was evaluated by serum creatinine (Scr), blood urea nitrogen (BUN), and tubular damage on PAS staining 48h after FA injection. Meanwhile, we examined four types of tubular cell death including tubular necrosis, apoptosis (TUNEL staining), pyroptosis (Caspase1, Pycard, and Txnip-1/2), and ferroptosis (Gpx4 and Acsl4). We also examined the renal expression of Nrf2-associated genes such as pro-inflammatory cytokines (Il6 and Tnfα) and antioxidative factors (Nqo1, Gclc, and Gclm) in Nrf2^−/−mice compared to that in Nrf2^+/+ mice. In addition, we explored the influence of Nrf2 deletion on the activity of methylenetetrahydrofolate dehydrogenase (MTHFD), which is an enzyme involved in FA systemic metabolism.

Results

AKI occurred in both Nrf2^+/+ and Nrf2^−/− mice. AKI features such as Scr, BUN, tubular damage degree on PAS staining, and tubular necrosis scores were more severe in Nrf2^−/− mice than in Nrf2^+/+ mice. The number of TUNEL positive nuclei in kidneys of Nrf2^−/− mice was higher than that in Nrf2^+/+ mice. However, the above four pyroptosis biomarkers showed no difference in the kidneys of both Nrf2^+/+ and Nrf2^−/− mice. Interestingly, renal anti-ferroptosis gene Gpx4 expression was downregulated while pro-ferroptosis gene Acsl4 was upregulated. In addition, renal pro-inflammatory Il6 and Tnfα genes were increased and antioxidative Nqo1, Gclc, and Gclm genes were decreased in Nrf2^−/− mice compared to in Nrf2^+/+ mice. Further, we found FA increased the activity of MTHFA; however, no difference of this enzyme was seen in Nrf2^−/− mice compared to Nrf2^+/+ mice.

Conclusion

Nrf2 deficiency aggravates FA-induced AKI in mice. Acute tubular protective roles of Nrf2 may be mediated by a combination of mechanisms such as anti-inflammation, antioxidative response, anti-apoptosis, and anti-ferroptosis.

Funding

• Government Support - Non-U.S.