mitotempo and Acute-Kidney-Injury

Ischemia/reperfusion (I/R) is a critical risk factor for acute kidney injury (AKI). Recent studies provided evidence that tubular epithelial cells (TEC)-associated inflammation aggravates kidney injury and impairs tissue repair after I/R injury. Here we demonstrated that the Nod-like receptor protein 3 (NLRP3) inflammasome is activated by mitochondrial reactive oxygen species (mROS) during I/R injury via direct interactions between the inflammasome and thioredoxin-interacting protein (TXNIP). Firstly, we found that NLRP3 inflammasome activation was induced by I/R injury, peaking at day 3 after reperfusion. Consistent with this observation, NLRP3 deletion significantly attenuated I/R-induced kidney damage and markers of inflammasome activation. Then, we observed mitochondrial dysfunction, characterized by ultrastructural changes and cytochrome C (Cyt c) redistribution. Mitochondria-targeted antioxidant MitoTEMPO prevented mROS overproduction and the decline in mitochondrial membrane potential (MMP) in vitro. MitoTEMPO treatment also inhibited NLRP3 inflammasome activation and co-localization of NLRP3 and TXNIP after simulated ischemia/reperfusion (SI/R) injury. Finally, we transfected HK-2 cells with TXNIP siRNA to explore the role of TXNIP in mROS-induced NLRP3 inflammasome activation. We found that TXNIP siRNA significantly inhibited NLRP3 inflammasome activation. These results demonstrate that NLRP3 inflammasome is activated through the mROS-TXNIP-NLRP3 pathway and provide a potential therapeutic target in ischemic AKI.

Topics: Acute Kidney Injury; Animals; Antioxidants; Carrier Proteins; Cell Proliferation; Cells, Cultured; Inflammasomes; Inflammation; Interleukin-1beta; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitochondria; NLR Family, Pyrin Domain-Containing 3 Protein; Organophosphorus Compounds; Piperidines; Reactive Oxygen Species; Reperfusion Injury; Thioredoxins

Acute kidney injury (AKI) is a complication of sepsis and leads to a high mortality rate. Human and animal studies suggest that mitochondrial dysfunction plays an important role in sepsis-induced multi-organ failure; however, the specific mitochondrial targets damaged during sepsis remain elusive. We used a clinically relevant cecal ligation and puncture (CLP) murine model of sepsis and assessed renal mitochondrial function using high-resolution respirometry, renal microcirculation using intravital microscopy, and renal function. CLP caused a time-dependent decrease in mitochondrial complex I and II/III respiration and reduced ATP. By 4 h after CLP, activity of manganese superoxide dismutase (MnSOD) was decreased by 50% and inhibition was sustained through 36 h. These events were associated with increased mitochondrial superoxide generation. We then evaluated whether the mitochondria-targeted antioxidant Mito-TEMPO could reverse renal mitochondrial dysfunction and attenuate sepsis-induced AKI. Mito-TEMPO (10 mg/kg) given at 6 h post-CLP decreased mitochondrial superoxide levels, protected complex I and II/III respiration, and restored MnSOD activity by 18 h. Mito-TEMPO also improved renal microcirculation and glomerular filtration rate. Importantly, even delayed therapy with a single dose of Mito-TEMPO significantly increased 96-h survival rate from 40% in untreated septic mice to 80%. Thus, sepsis causes sustained inactivation of three mitochondrial targets that can lead to increased mitochondrial superoxide. Importantly, even delayed therapy with Mito-TEMPO alleviated kidney injury, suggesting that it may be a promising approach to treat septic AKI.

Topics: Acute Kidney Injury; Adenosine Triphosphate; Animals; Antioxidants; Body Temperature Regulation; Cell Respiration; Disease Models, Animal; Electron Transport Chain Complex Proteins; Electron Transport Complex I; Electron Transport Complex II; Electron Transport Complex III; Electron Transport Complex IV; Kidney; Male; Mice; Mice, Inbred C57BL; Microcirculation; Mitochondria; Organophosphorus Compounds; Oxidative Stress; Piperidines; Renal Circulation; Sepsis; Superoxide Dismutase; Time Factors

Sepsis-induced acute kidney injury (SAKI) is a frequent complication of infant sepsis that approximately doubles the mortality rate. The poor prognosis of these patients is a result of care that is mainly supportive, nontargeted, and usually begun only after symptoms of the systemic inflammatory response syndrome are observed. Preclinical studies from relevant rodent models of SAKI suggest that mitochondria-targeted antioxidants may be a new mode of therapy that could promote recovery.

Topics: Acute Kidney Injury; Animals; Antioxidants; Disease Models, Animal; Humans; Infant; Mice; Mitochondria; Organophosphorus Compounds; Piperidines; Rats; Sepsis