Ivacaftor attenuates gentamicin-induced ototoxicity through the CFTR-Nrf2-HO1/NQO1 pathway.

OBJECTIVES: Gentamicin is one of the most common ototoxic drugs that can lower patients' quality of life. Oxidative stress is a key factors inducing sensory hair cell death during gentamicin administration. So far, there are no effective drugs to prevent or treat gentamicin- induced hearing loss. A recent study found cystic fibrosis transmembrane conductance regulator (CFTR) as a new target to modulate cellular oxidative balance. The objective of this study was to estimate the effect of the CFTR activator ivacaftor on gentamicin-induced ototoxicity and determine its mechanism. METHODS: The hair cell count was analyzed by Myosin 7a staining. Apoptosis was analyzed by TUNEL Apoptosis Kit. Cellular reactive oxygen species (ROS) level was detected by DCFH-DA probes. The Nrf2 related proteins expression levels were analyzed by western blot. RESULTS: An in vitro cochlear explant model showed that gentamicin caused ROS accumulation in sensory hair cells and induced apoptosis, and this effect was alleviated by pretreatment with ivacaftor. Western blotting showed that ivacaftor administration markedly increased the protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO1), and NAD(P)H:quinone oxidoreductase 1 (NQO1). The protective effect of ivacaftor was abolished by the Nrf2 inhibitor ML385. DISCUSSION: Our results indicate the protective role of the CFTR-Nrf2-HO1/NQO1 pathway in gentamicin-induced ototoxicity. Ivacaftor may be repositioned or repurposed towards aminoglycosides-induced hearing loss.

Zinc ameliorates acrylamide-induced oxidative stress and apoptosis in testicular cells via Nrf2/HO-1/NfkB and Bax/Bcl2 signaling pathway.

BACKGROUND: Acrylamide is a toxic substance formed in some foods that require high-temperature cooking processes and has been implicated as a gonadotoxic agent. Zinc, on the other hand, is a known antioxidant with fertility-enhancing properties. Hence, this study was designed to explore the possible ameliorative effect of zinc in acrylamide-induced gonadotoxicity. METHODS: Twenty-four male Wistar rats were randomized into control, acrylamide (10 mg/kg of acrylamide), acrylamide + 1 mg/kg of zinc, and acrylamide + 3 mg/kg of zinc. The administration was via the oral route and lasted for 56 days. RESULTS: Zinc treatment ameliorated acrylamide-impaired sperm quality, normal testicular histoarchitecture, and hormonal balance, which was accompanied by increased testicular malondialdehyde and interleukin-1ß and decreased testicular superoxide dismutase (SOD) and catalase (CAT). Furthermore, zinc prevented acrylamide-induced downregulation of testicular nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and B-cell lymphoma 2 (BCl2) expression and upregulation of testicular nuclear factor kappa B (NF-κB) and bcl-2-like protein 4 (bax) expression. CONCLUSION: In conclusion, zinc may protect against acrylamide-induced testicular toxicity, mediated by its antioxidant, anti-inflammatory, and antiapoptotic effects.

Heme oxygenase-1 is an equid alphaherpesvirus 8 replication restriction host protein and suppresses viral replication via the PKCß/ERK1/ERK2 and NO/cGMP/PKG pathway.

Equid alphaherpesvirus 8 (EqHV-8) is one of the most economically important viruses that is known to cause severe respiratory disease, abortion, and neurological syndromes in equines. However, no effective vaccines or therapeutic agents are available to control EqHV-8 infection. Heme oxygenase-1 (HO-1) is an antioxidant defense enzyme that displays significant cytoprotective effects against different viral infections. However, the literature on the function of HO-1 during EqHV-8 infection is little. We explored the effects of HO-1 on EqHV-8 infection and revealed its potential mechanisms. Our results demonstrated that HO-1 induced by cobalt-protoporphyrin (CoPP) or HO-1 overexpression inhibited EqHV-8 replication in susceptible cells. In contrast, HO-1 inhibitor (zinc protoporphyria) or siRNA targeting HO-1 reversed the anti-EqHV-8 activity. Furthermore, biliverdin, a metabolic product of HO-1, mediated the anti-EqHV-8 effect of HO-1 via both the protein kinase C (PKC)ß/extracellular signal-regulated kinase (ERK)1/ERK2 and nitric oxide (NO)-dependent cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signaling pathways. In addition, CoPP protected the mice by reducing the EqHV-8 infection in the lungs. Altogether, these results indicated that HO-1 can be developed as a promising therapeutic strategy to control EqHV-8 infection.IMPORTANCEEqHV-8 infections have threatened continuously donkey and horse industry worldwide, which induces huge economic losses every year. However, no effective vaccination strategies or drug against EqHV-8 infection until now. Our present study found that one host protien HO-1 restrict EqHV-8 replication in vitro and in vivo. Furthermore, we demonstrate that HO-1 and its metabolite biliverdin suppress EqHV-8 relication via the PKCß/ERK1/ERK2 and NO/cGMP/PKG pathways. Hence, we believe that HO-1 can be developed as a promising therapeutic strategy to control EqHV-8 infection.

Cocoa flavanols, Nrf2 activation, and oxidative stress in peripheral artery disease: mechanistic findings in muscle based on outcomes from a randomized trial.

The pathophysiology of muscle damage in peripheral artery disease (PAD) includes increased oxidant production and impaired antioxidant defenses. Epicatechin (EPI), a naturally occurring flavanol, has antioxidant properties that may mediate the beneficial effects of natural products such as cocoa. In a phase II randomized trial, a cocoa-flavanol-rich beverage significantly improved walking performance compared with a placebo in people with PAD. In the present work, the molecular mechanisms underlying the therapeutic effect of cocoa flavanols were investigated by analyzing baseline and follow-up muscle biopsies from participants. Increases in nuclear factor erythroid 2-related factor 2 (Nrf2) target antioxidants heme oxygenase-1 (HO-1) and NAD(P)H dehydrogenase [quinone] 1 (NQO1) in the cocoa group were significantly associated with reduced accumulation of central nuclei, a myopathy indicator, in type II muscle fibers (P = 0.017 and P = 0.023, respectively). Protein levels of the mitochondrial respiratory complex III subunit, cytochrome b-c1 complex subunit 2 (UQCRC2), were significantly higher in the cocoa group than in the placebo group (P = 0.032), and increases in UQCRC2 were significantly associated with increased levels of Nrf2 target antioxidants HO-1 and NQO1 (P = 0.001 and P = 0.035, respectively). Exposure of non-PAD human myotubes to ex vivo serum from patients with PAD reduced Nrf2 phosphorylation, an indicator of activation, increased hydrogen peroxide production and oxidative stress, and reduced mitochondrial respiration. Treatment of myotubes with EPI in the presence of serum from patients with PAD increased Nrf2 phosphorylation and protected against PAD serum-induced oxidative stress and mitochondrial dysfunction. Overall, these findings suggest that cocoa flavanols may enhance antioxidant capacity in PAD via Nrf2 activation.NEW & NOTEWORTHY The current study supports the hypothesis that in people with PAD, cocoa flavanols activate Nrf2, thereby increasing antioxidant protein levels, protecting against skeletal muscle damage, and increasing mitochondrial protein abundance. These results suggest that Nrf2 activation may be an important therapeutic target for improving walking performance in people with PAD.

The antioxidant effect of preischemic dexmedetomidine in a rat model: increased expression of Nrf2/HO-1 via the PKC pathway

Abstract Background The precise underlying mechanism of antioxidant effects of dexmedetomidine-induced neuroprotection against cerebral ischemia has not yet been fully elucidated. Activation of Nuclear factor erythroid 2-related factor (Nrf2) and Heme Oxygenase-1 (HO-1) represents a major antioxidant-defense mechanism. Therefore, we determined whether dexmedetomidine increases Nrf2/HO-1 expression after global transient cerebral ischemia and assessed the involvement of Protein Kinase C (PKC) in the dexmedetomidine-related antioxidant mechanism. Methods Thirty-eight rats were randomly assigned to five groups: sham (n = 6), ischemic (n = 8), chelerythrine (a PKC inhibitor; 5 mg.kg-1 IV administered 30 min before cerebral ischemia) (n = 8), dexmedetomidine (100 µg.kg-1 IP administered 30 min before cerebral ischemia (n = 8), and dexmedetomidine + chelerythrine (n = 8). Global transient cerebral ischemia (10 min) was applied in all groups, except the sham group; histopathologic changes and levels of nuclear Nrf2 and cytoplasmic HO-1 were examined 24 hours after ischemia insult. Results We found fewer necrotic and apoptotic cells in the dexmedetomidine group relative to the ischemic group (p< 0.01) and significantly higher Nrf2 and HO-1 levels in the dexmedetomidine group than in the ischemic group (p< 0.01). Additionally, chelerythrine co-administration with dexmedetomidine attenuated the dexmedetomidine-induced increases in Nrf2 and HO-1 levels (p< 0.05 and p< 0.01, respectively) and diminished its beneficial neuroprotective effects. Conclusion Preischemic dexmedetomidine administration elicited neuroprotection against global transient cerebral ischemia in rats by increasing Nrf2/HO-1 expression partly via PKC signaling, suggesting that this is the antioxidant mechanism underlying dexmedetomidine-mediated neuroprotection.