Related Experiment Video
Updated: Apr 27, 2026
Modeling Hypoxia/Reoxygenation Injury in Proximal Tubular Epithelial Cells
Published on: November 21, 2025
Complement-dependent NADPH oxidase enzyme activation in renal ischemia/reperfusion injury
S Simone1, F Rascio2, G Castellano1
1Nephrology, Dialysis, and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari "Aldo Moro," 70121 Bari, Italy.
Abstract:
NADPH oxidase plays a central role in mediating oxidative stress during heart, liver, and lung ischemia/reperfusion injury, but limited information is available about NADPH oxidase in renal ischemia/reperfusion injury. Our aim was to investigate the activation of NADPH oxidase in a swine model of renal ischemia/reperfusion damage. We induced renal ischemia/reperfusion in 10 pigs, treating 5 of them with human recombinant C1 inhibitor, and we collected kidney biopsies before ischemia and 15, 30, and 60 min after reperfusion. Ischemia/reperfusion induced a significant increase in NADPH oxidase 4 (NOX-4) expression at the tubular level, an upregulation of NOX-2 expression in infiltrating monocytes and myeloid dendritic cells, and 8-oxo-7,8-dihydro-2'-deoxyguanosine synthesis along with a marked upregulation of NADPH-dependent superoxide generation. This burden of oxidative stress was associated with an increase in tubular and interstitial expression of the myofibroblast marker α-smooth muscle actin (α-SMA). Interestingly, NOX-4 and NOX-2 expression and the overall NADPH oxidase activity as well as α-SMA expression and 8-oxo-7,8-dihydro-2'-deoxyguanosine synthesis were strongly reduced in C1-inhibitor-treated animals. In vitro, when we incubated tubular cells with the anaphylotoxin C3a, we observed an enhanced NADPH oxidase activity and α-SMA protein expression, which were both abolished by NOX-4 silencing. In conclusion, our findings suggest that NADPH oxidase is activated during ischemia/reperfusion in a complement-dependent manner and may play a potential role in the pathogenesis of progressive renal damage in this setting.
Insights
NADPH oxidase activation contributes to kidney damage after ischemia/reperfusion. C1 inhibitor treatment reduced oxidative stress and markers of progressive renal damage, suggesting a therapeutic target.
Area of Science:
- Nephrology
- Immunology
- Oxidative Stress Research
Background:
- NADPH oxidase (NOX) is implicated in oxidative stress in various organs during ischemia/reperfusion (I/R) injury.
- Limited data exists on NOX involvement in renal I/R injury.
Purpose of the Study:
- To investigate NADPH oxidase activation in a swine model of renal I/R injury.
- To explore the role of complement component C1 inhibitor in modulating this response.
Main Methods:
- Renal I/R was induced in pigs; 5 received human recombinant C1 inhibitor.
- Kidney biopsies were analyzed for NOX-4, NOX-2, 8-oxo-7,8-dihydro-2'-deoxyguanosine, and α-SMA expression.
- In vitro studies examined tubular cell responses to C3a with and without NOX-4 silencing.
Main Results:
- Renal I/R increased NOX-4, NOX-2, oxidative stress markers (8-oxo-7,8-dihydro-2'-deoxyguanosine), and α-SMA expression.
- C1 inhibitor treatment significantly reduced these markers.
- In vitro, C3a enhanced NOX activity and α-SMA, effects blocked by NOX-4 silencing.
Conclusions:
- NADPH oxidase is activated in renal I/R injury, potentially via complement activation.
- NOX-4 and NOX-2 contribute to oxidative stress and myofibroblast activation.
- C1 inhibitor mitigates these effects, suggesting a role in preventing progressive renal damage.
Related Concept Videos
01:29Acute Kidney Injury II: Pathophysiology
01:25Bioactivation and Tissue Toxicity