Antioxidants & Redox Signaling

Doxorubicin (Dox) is a potent chemotherapy agent, yet its clinical use is hampered by cardiotoxicity. Although extensive research has focused on Dox-induced cardiotoxicity (DIC), its mechanism remains elusive. Recent evidence implicates ferroptosis as a key contributor to DIC. The 15-lipoxygenase-1 (ALOX15), involved in lipid peroxidation, is known to play an essential role in ischemia-induced myocardial damage and heart failure; however, its function in DIC is undefined. This study seeks to elucidate the role of ALOX15 in DIC and unravel its underlying mechanism.

Both ALOX15 mRNA and protein levels were elevated in DIC models in vivo and in vitro. Inhibition or silencing of ALOX15 ameliorated lipid peroxidation, ferroptosis, and cardiac dysfunction in Dox-treated mice. Consistently, ALOX15 loss of function protected H9C2 cells against Dox and RSL3-induced toxicity. In addition, we found that linoleic acid increased the susceptibility of H9C2 cells toward Dox-induced damage, which was abolished by ALOX15 inhibition. Furthermore, Alox15 overexpression aggravated Dox-induced cell damage by aggravating reactive oxygen species (ROS)-mediated ferroptosis. Mechanistically, we discovered that the amelioration of Dox-induced ferroptosis by ALOX15 loss of function occurred through inhibiting the ROS-mediated mitogen-activated protein kinase (MAPK) signaling pathway activation.

These results reveal that ALOX15 regulates ferroptosis through ROS-mediated MAPK signaling pathway in DIC, suggesting a potential therapeutic target for DIC intervention. Antioxid. Redox Signal. 43, 363–380.

Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder among the elderly. Uric acid (UA), the end product of purine metabolism, functions as a potent free radical scavenger and helps mitigate oxidative stress. Several epidemiological studies revealed that serum UA levels are negatively correlated with the risk of AD; however, the molecular mechanisms remain unclear. Notably, β-amyloid (Aβ) deposition is implicated in the disruption of mitophagy, leading to neuronal apoptosis. In this study, we aim to elucidate the link between UA and AD and explore the underlying mechanisms.

We demonstrated that UA improved cognitive impairment in 5×FAD mice and reduced neuronal apoptosis both in vivo and in vitro. UA reversed the expression of phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1), p-Parkin^S65, parkin, microtubule-associated protein 1 light chain 3 II/I, and p62 proteins inhibited by Aβ treatment, alleviated Aβ induced mitochondrial dysfunction, and disturbed dynamics. We found that UA activated nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1(HO-1) signaling both in vivo and in vitro. Furthermore, ML385, a Nrf2-specific inhibitor, reversed the increase in mitochondrial membrane potential and mitophagy promoted by UA and increased neuronal apoptosis in HT22 cells. The antiapoptotic effects of UA in HT22 cells were prevented by treatment with small interfering RNAs targeting PINK1.

These data suggest that UA stimulates PINK1/parkin-mediated mitophagy reducing Aβ-induced neuronal apoptosis through the Nrf2/HO-1 pathway, which plays a neuroprotective role in AD. Our findings confirmed that UA effectively reduces neuronal damage and cognitive impairment, highlighting its potential clinical applications in the treatment of AD. Antioxid. Redox Signal. 43, 381–399.

Oxidative stress is a key factor in inducing cellular senescence and age-related diseases. When the redox balance within the body is disrupted, sustained oxidative stress can lead to cellular senescence. The accumulation of senescent cells, in turn, triggers a variety of age-related diseases. Peroxiredoxin 6 (Prdx6) is a critical target in the intracellular regulation of redox homeostasis.

Prdx6 is a widely expressed antioxidant enzyme and the sole member of the peroxiredoxin family endowed with multiple enzymatic functions, including peroxidase activity along with acidic calcium-independent phospholipase A2 (aiPLA2) and lysophosphatidylcholine acyltransferase (LPCAT) activities. Its fundamental physiological functions involve protecting against oxidative stress and maintaining phospholipid homeostasis. Recent studies have shown that Prdx6 is widely involved in the regulation of cellular senescence and influences the development and progression of various age-related diseases.

Cellular senescence and age-related diseases, due to their complex mechanisms, lack effective treatments. Therefore, there is an urgent need to identify new therapeutic targets. This review discusses the biological characteristics of Prdx6 and its pathophysiological roles in cellular senescence and age-related diseases. Prdx6 may serve as a potential target for modulating cellular senescence and age-related diseases.

The regulatory mechanisms of Prdx6 in age-related diseases warrant further investigation. Additionally, conducting drug screening to identify more molecules that can specifically target Prdx6 will provide new strategies for the treatment of age-related diseases. Antioxid. Redox Signal. 43, 400–426.

Ischemic stroke (IS) remains the third leading cause of death, and the treatment of acute ischemic stroke (AIS) is still a formidable challenge to clinicians. This study tested the hypothesis that combined silencing Mnf2 gene in adipose-derived mesenchymal stem cells (ADMSCs^sil-Mnf2) and melatonin (Mel) therapy was superior to monotherapy on attenuating the brain infarct volume (BIV) and improving neurological function in AIS rats.

In vitro and in vivo studies were conducted. In vitro results showed that as compared with the controls (i.e., ADMSCs/N2a cells), the cellular/protein levels of oxidative stress/reactive oxygen species (ROS)/mitochondrial and DNA damaged/apoptotic/cell stress signaling (tumor necrosis factor [TNF] receptor associated factor 6/ apoptosis signal regulating kinase/MKK^4/7/JUN/ERK^1/2/c-Jun) biomarkers were significantly increased in these cells treated by H₂O₂ that were significantly reversed by ADMSCs^sil-Mnf2 or Mel and further significantly reversed by combined therapy (all p < 0.0001). Animals were categorized into groups 1 (sham-operated control)/2 (AIS)/3 (AIS + Mel)/4 (AIS + ADMSCs^sil-Mnf2)/5 (AIS + Mel-ADMSCs^sil-Mnf2) and euthanized by day 28 after AIS. By day 28, the BIV and the brain infarct area (BIA) were lowest in group 1/highest in group 2/significantly lower in group 5 than in groups 3 and 4/significantly increased in group 4 than in group 3, whereas the neurological function displayed an opposite manner of BIV (all p < 0.0001). The protein expressions of oxidative stress/mitochondrial damaged/apoptotic/inflammatory/cell stress signaling biomarkers displayed an identical pattern, whereas the protein expressions of mitochondrial biogenesis/antioxidants and cellular level of neuronal cells exhibited an opposite manner of BIV among the groups (all p < 0.0001).

ADMSCs^sil-Mnf2 and Mel combined therapy offered synergic effects on attenuating the BIV/BIA and preserving neurological function in rodents after AIS mainly through suppressing oxidative stress/ROS/inflammatory signalings and upregulating antioxidants. Combined ADMSCs^sil-Mnf2 and Mel therapy offered additional benefits on protecting the brain against AIS in rodents. Antioxid. Redox Signal. 43, 427–447.

We previously demonstrated that aryl hydrocarbon receptor (AhR) activation attenuates the cytoprotective effect of hydrogen sulfide (H₂S), leading to indoxyl sulfate (IS)-mediated renal tubular damage. However, it is unclear whether this pathway would be present in an in vivo uremic model.

In a rat chronic kidney disease (CKD) model with 5/6 nephrectomized (Nx), we found that poor renal filtration is associated with accumulation of IS and homocysteine (Hcy), an H₂S precursor. Compared with controls, the protein and mRNA levels of H₂S-producing enzymes, including cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase, were attenuated in Nx kidneys. Since the transcription factor, specificity protein 1 (Sp1), acts as an upstream regulator of these enzyme expressions, we found that the protein level and activity of Sp1 were significantly decreased in Nx kidneys. Interestingly, employing the blocker of the AhR CH-223191 not only reverses the decrease in H₂S-producing enzymes and Sp1, but it also reverses H₂S reduction in Nx rats. These are associated with the mitigation of plasma Hcy accumulation, renal excretion, perfusion insufficiency, and tubular damage. Moreover, the oxidative stress in Nx kidneys due to increased superoxide formation and decreased glutathione contents was also attenuated by AhR inhibition.

Our findings highlight the deleterious effect of AhR activation on renal H₂S formation may be due to IS accumulation and underline AhR blockade as a novel therapy for CKD.

AhR is detrimental to Sp1 function in vivo, leading to impeding renal H₂S generation and exacerbating oxidative stress during CKD progression. Antioxid. Redox Signal. 43, 448–464.

Total flavones of Rhododendron (TFR) extracted from the flowers of Rhododendron contains bioactive components. We investigated the main components of TFR and explored the role of TFR in microglial polarization in poststroke mice with depression-like behavior.

Using ultraperformance liquid chromatography–tandem mass spectrometry, we identified the main and potential active compounds in TFR as kaempferol, astragalin, epicatechin, myricetin, rutin, isoquercitrin, quercetin, and quercitrin. In addition, we demonstrated that TFR (60 and 120 mg/kg) efficiently ameliorated depression-like behavior in mice and promoted microglial polarization to the M2 subtype in the mouse hippocampal tissues. We also revealed that TFR (160 mg/L) facilitated microglial polarization to the M2 subtype following oxygen–glucose deprivation/reoxygenation (OGD/R) in vitro. RNA sequencing revealed the upregulation of NADPH oxidase 2 (NOX2) in the mouse brain tissues after cerebral ischemia/reperfusion (I/R) injury. TFR (120 mg/kg) inhibited NOX2 expression in the hippocampal tissues of cerebral I/R mice. In addition, TFR (160 mg/L) downregulated NOX2 expression in OGD/R-treated microglial cells and decreased reactive oxygen species (ROS) production. Notably, NOX2 inhibition promoted microglial polarization to the M2 subtype.

TFR promotes microglial polarization to the M2 subtype by inhibiting the NOX2/ROS pathway. Antioxid. Redox Signal. 43, 465–481.