LncRNA NEAT1 aggravates human microvascular endothelial cell injury by inhibiting the Apelin/Nrf2/HO-1 signalling pathway in type 2 diabetes mellitus with obstructive sleep apnoea

Long noncoding RNAs (lncRNAs) regulate the progression of type 2 diabetes mellitus complicated with obstructive sleep apnoea (T2DM-OSA). However, the role of the lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) in T2DM-OSA remains unknown. This study aimed to reveal the function of NEAT1 in T2DM-OSA and the underlying mechanism. KKAy mice were exposed to intermittent hypoxia (IH) or intermittent normoxia to generate a T2DM-OSA mouse model. HMEC-1 cells were treated with high glucose (HG) and IH to construct a T2DM-OSA cell model. RNA expression was detected by qRT-PCR. The protein expression of Apelin, NF-E2-related factor 2 (Nrf2), haem oxygenase-1 (HO-1), and up-frameshift suppressor 1 (UPF1) was assessed using western blot. Cell injury was evaluated using flow cytometry, enzyme-linked immunosorbent assay, and oxidative stress kit assays. RIP, RNA pull-down, and actinomycin D assays were performed to determine the associations between NEAT1, UPF1, and Apelin. NEAT1 expression was upregulated in the aortic vascular tissues of mice with T2DM exposed to IH and HMEC-1 cells stimulated with HG and IH, whereas Apelin expression was downregulated. The absence of NEAT1 protected HMEC-1 cells from HG- and IH-induced damage. Furthermore, NEAT1 destabilized Apelin mRNA by recruiting UPF1. Apelin overexpression decreased HG- and IH-induced injury to HMEC-1 cells by activating the Nrf2/HO-1 pathway. Moreover, NEAT1 knockdown reduced HG- and IH-induced injury to HMEC-1 cells through Apelin. NEAT1 silencing reduced HMEC-1 cell injury through the Apelin/Nrf2/HO-1 signalling pathway in T2DM-OSA.Abbreviations: LncRNAs, long non-coding RNAs; T2DM, type 2 diabetes mellitus; OSA, obstructive sleep apnoea; NEAT1, nuclear paraspeckle assembly transcript 1; IH, intermittent hypoxia; HMEC-1, human microvascular endothelial cells; HG, high glucose; Nrf2, NF-E2-related factor 2; UPF1, up-frameshift suppressor 1; HO-1, haem oxygenase-1; qRT-PCR, quantitative real-time polymerase chain reaction; ELISA, enzyme-linked immunosorbent assay; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; TNF-α, tumour necrosis factor-α; CCK-8, Cell Counting Kit-8; IL-1β, interleukin-1β; ROS, reactive oxygen species; MDA, malondialdehyde; SOD, superoxide dismutase; RIP, RNA immunoprecipitation; SD, standard deviations; GSH, glutathione; AIS, acute ischaemic stroke; HMGB1, high mobility group box-1 protein; TLR4, toll-like receptor 4.

Procyanidin alleviates ferroptosis and inflammation of LPS-induced RAW264.7 cell via the Nrf2/HO-1 pathway

Inflammation is a common occurrence in many medical conditions and is a natural defense mechanism of the human body. Ferroptosis, an iron-dependent form of cell death related to lipid peroxide build-up, has been found to be involved in inflammation. The anti-inflammatory effects of procyanidin, however, are not yet fully understood. Through network pharmacology and bioinformatics analysis, it was suggested that procyanidin could modulate ferroptosis and cause anti-inflammatory effects on RAW264.7 cells. This was further evidenced through molecular docking, molecular dynamics, and in vitro experiments. The results indicated that procyanidin could diminish inflammation in LPS-induced RAW264.7 cells by regulating ferroptosis via the Nrf2/HO-1/Keap-1 pathway. In conclusion, procyanidin supplementation might be an effective way to reduce inflammation by decreasing the release of inflammatory cytokines and suppressing ferroptosis.

Cobalt protoporphyrin promotes heme oxygenase 1 expression and ameliorates cardiac dysfunction in long-term fasting mice

BACKGROUND

The association between malnutrition and cardiac dysfunction has been reported. Heme oxygenase (HO)-1 played protective roles in the animals functioning as a myocardial infarction, heart failure, or cardiomyopathy model. We hypothesized that the administration of HO-1 inducer, cobalt protoporphyrin (CoPP) reduces oxidative stress and ameliorates cardiac systolic dysfunction in long-term fasting mice.

METHODS

C57BL/6 J mice were classified into three groups: fed mice (fed group), 48-h fasting mice with a single intraperitoneal injection of the corresponding vehicle (fasting group), and 48-h fasting mice with a single intraperitoneal injection of 5 mg/kg CoPP (CoPP group).

RESULTS

The fasting group showed a significant increase in heme and 4-hydroxy-2-nonenal (4HNE) protein in the heart tissue, and reduced left ventricular ejection fraction (LVEF) when compared with the fed group. The CoPP group showed significantly increased protein levels of nuclear factor-erythroid 2-related factor 2 and HO-1, and increased mRNA expression levels of HO-1, peroxisome proliferator-activated receptor gamma coactivator 1-alpha, forkhead box protein O1, sirtuin-1, cyclooxygenase 2, and superoxide dismutase 2, and reduced levels of heme and 4HNE protein when compared with the fasting group. LVEF were significantly higher in the CoPP group than in the fasting group.

CONCLUSIONS

Administration of CoPP reduced heme accumulation and oxidative stress, and ameliorated cardiac systolic dysfunction in long-term fasting mice. This study suggests that heme accumulation may be associated with impaired cardiac function induced by long-term fasting and that HO-1 may be a key factor or therapeutic target.

Nifuroxazide attenuates indomethacin-induced renal injury by upregulating Nrf2/HO-1 and cytoglobin and suppressing NADPH-oxidase, NF-κB, and JAK-1/STAT3 signals

Indomethacin (INDO) is an NSAID with remarkable efficacy and widespread utilization for alleviating pain. Nevertheless, renal function impairment is an adverse reaction linked to INDO usage. Nifuroxazide (NFX), an oral nitrofuran antibiotic, is frequently employed as an intestinal anti-infective agent. Our study aimed to investigate the renoprotective effects of NFX against INDO-induced nephrotoxicity and explore the protection mechanisms. Four groups of rats were allocated to (I) the normal control, (II) the NFX-treated (50 mg/kg), (III) INDO control (20 mg/kg), and (IV) NFX + INDO. NFX attenuates renal impairment in INDO-induced renal injury, proved by decreasing serum levels of urea, creatinine, uric acid, and NGAL while the albumin was elevated. NFX mitigates renal oxidative stress by decreasing MDA levels and restoring the antioxidants' GSH and SOD levels mediated by upregulating Nrf2, HO-1, and cytoglobin pathways. NFX mitigated renal inflammation and effectively decreased MPO, IL-1β, and TNF-α levels in the rat's kidney mediated by significant downregulation of NADPH-oxidase and NF-κB expression and suppression of JAK-1 and STAT3 phosphorylation. NFX mitigates renal apoptosis by decreasing the expression of cleaved caspase-3 expression. In conclusion, NFX treatment prevents INDO nephrotoxicity by regulating Nrf2/HO-1, cytoglobin, NADPH-oxidase, NF-κB, and JAK-1/STAT3 signals.

Role of Nrf2/HO-1, PPAR-γ, and cytoglobin signals in the pathogenesis of methotrexate-induced testicular intoxication in rats and the protective effect of diacerein

Methotrexate (MTX) is an inhibitor of folic acid reductase used in managing a variety of malignancies. Testicular injury by MTX is one of its serious adverse effects. The current investigation aims to assess the protective effects of diacerein (DIA) on testicular injury by MTX and clarify the possible underlying mechanisms. Testicular injury in rats was induced by a single injection of 20 mg/kg body weight of MTX. DIA was given in 25 mg/kg body weight/day and 50 mg/kg body weight/day doses for 10 days. Compared to the MTX group, DIA attenuated testicular intoxication as evidenced by improvement of testicular histopathological abnormalities and increased serum testosterone and luteinizing hormone. DIA attenuated testicular oxidative stress changes by lowering testicular MDA and boosting GSH content and SOD activity. Moreover, administration of DIA attenuated MTX-induced testicular inflammation, as proved by decreased TNF-α and IL-6. At the molecular level, DIA induced significant upregulation in Nrf2, HO-1, PPAR-γ, and cytoglobin protein expression. The present results proved that DIA, in a dose-dependent manner, exhibited notable amelioration of testicular toxicity induced by MTX through augmentation of anti-inflammatory and antioxidant effects combined by upregulating Nrf2/HO-1, PPAR-γ, and cytoglobin signaling.

Revealing the pharmacological mechanisms of nao-an dropping pill in preventing and treating ischemic stroke via the PI3K/Akt/eNOS and Nrf2/HO-1 pathways

Nao-an Dropping Pill (NADP) is a Chinese patent medicine which commonly used in clinic for ischemic stroke (IS). However, the material basis and mechanism of its prevention or treatment of IS are unclear, then we carried out this study. 52 incoming blood components were resolved by UHPLC-MS/MS from rat serum, including 45 prototype components. The potential active prototype components hydroxysafflor yellow A, ginsenoside F1, quercetin, ferulic acid and caffeic acid screened by network pharmacology showed strongly binding ability with PIK3CA, AKT1, NOS3, NFE2L2 and HMOX1 by molecular docking. In vitro oxygen-glucose deprivation/reperfusion (OGD/R) experimental results showed that NADP protected HA1800 cells from OGD/R-induced apoptosis by affecting the release of LDH, production of NO, and content of SOD and MDA. Meanwhile, NADP could improve behavioral of middle cerebral artery occlusion/reperfusion (MCAO/R) rats, reduce ischemic area of cerebral cortex, decrease brain water and glutamate (Glu) content, and improve oxidative stress response. Immunohistochemical results showed that NADP significantly regulated the expression of PI3K, Akt, p-Akt, eNOS, p-eNOS, Nrf2 and HO-1 in cerebral ischemic tissues. The results suggested that NADP protects brain tissues and ameliorates oxidative stress damage to brain tissues from IS by regulating PI3K/Akt/eNOS and Nrf2/HO-1 signaling pathways.

Endotoxin tolerance ameliorates lipopolysaccharide/D-galactosamine-induced acute liver failure by negative regulation of the NF-κB/NLRP3 and activation of Nrf2/HO-1 via Sitr1

Acute liver failure (ALF) is a potentially fatal disorder characterized by extensive hepatocyte necrosis and rapid decline in liver function. Numerous factors, including oxidative stress, cell death, and inflammatory responses, are associated with its pathogenesis. Endotoxin tolerance (ET) refers to the phenomenon in which the body or cells exhibit low or no response to high-dose lipopolysaccharide (LPS) stimulation after pre-stimulation with low-dose LPS. However, the specific mechanism through which ET regulates LPS/D-galactosamine (D-GalN)-induced ALF remains unclear. An ALF mouse model was established by intraperitoneal injection of D-GalN (400 mg/kg) and LPS (10 mg/kg). A low dose of LPS (0.1 mg/kg/d) was continuously administered to mice for 5 d before modeling to assess the protective effect of ET. The data from this study showed that ET alleviated the inflammatory response in mice with LPS/D-GalN-induced ALF. ET inhibited LPS-induced oxidative damage and pyroptosis in macrophages in vitro. RNA sequencing analysis showed that the NF-κB/NLRP3 pathway was linked to the anti-inflammatory and antioxidative effects of ET. Furthermore, using western blot, RT-qPCR, and immunofluorescence, we verified that ET inhibited the NF-κB/NLRP3 pathway and triggered the Nrf2/HO-1 signaling pathway to attenuate oxidative stress and cell pyroptosis. Sirt1 knockdown reversed this protective effect. In summary, our research elucidates that ET prevents ALF advancement by upregulating Sirt1 levels, triggering the Nrf2/HO-1 signaling axis, and suppressing the NF-κB/NLRP3 signaling cascade to inhibit oxidative stress and cell pyroptosis. Our results provide a mechanistic explanation for the protective effect of ET against ALF.

Linagliptin ameliorates tacrolimus-induced renal injury: role of Nrf2/HO-1 and HIF-1α/CTGF/PAI-1

BACKGROUND

Tacrolimus (TAC) is a frequently used immunosuppressive medication in organ transplantation. However, its nephrotoxic impact limits its long-term usage. This study aims to investigate the effect of linagliptin (Lina) on TAC-induced renal injury and its underlying mechanisms.

METHODS AND RESULTS

Thirty-two Sprague Dawley rats were treated with TAC (1.5 mg/kg/day, subcutaneously) and/or Lina (5 mg/kg/day, orally) for 4 weeks. Histological examination was conducted, and serum and urinary biomarkers were measured to assess kidney function and integrity. Furthermore, ELISA, Western blot analysis and immunohistochemical assay were employed to determine signaling molecules of oxidative stress, profibrogenic, hypoxic, and apoptotic proteins. Tacrolimus caused renal dysfunction and histological deterioration evidenced by increased serum creatinine, blood urea nitrogen (BUN), urinary cystatin C, and decreased serum albumin as well as elevated tubular injury and interstitial fibrosis scores. Additionally, TAC significantly increased the expression of collagen type-1, alpha-smooth muscle actin (α-SMA), plasminogen activator inhibitor-1 (PAI-1), and transforming growth factor-beta1 (TGF-β1) renal content. Moreover, TAC decreased the expression of nuclear factor erythroid-2-related factor2 (Nrf2), heme oxygenase 1 (HO-1), and mitochondrial superoxide dismutase (SOD2). In addition, TAC increased protein expression of hypoxia-inducible factor1-alpha (HIF-1α), connective tissue growth factor (CTGF), inducible nitric oxide synthase (iNOS), 8-hydroxy-2-deoxyguanosine (8-OHdG), as well as nitric oxide (NO), 4-hydroxynonenal, caspase-3 and Bax renal contents. Furthermore, TAC decreased Bcl-2 renal contents. The Lina administration markedly attenuated these alterations.

CONCLUSION

Lina ameliorated TAC-induced kidney injury through modulation of oxidative stress, hypoxia, and apoptosis related proteins.

Exploring the pathophysiological influence of heme oxygenase-1 on neuroinflammation and depression: A study of phytotherapeutic-based modulation

BACKGROUND

The heme oxygenase (HO) system plays a significant role in neuroprotection and reduction of neuroinflammation and neurodegeneration. The system, via isoforms HO-1 and HO-2, regulates cellular redox balance. HO-1, an antioxidant defense enzyme, is highlighted due to its association with depression, characterized by heightened neuroinflammation and impaired oxidative stress responses.

METHODOLOGY

We observed the pathophysiology of HO-1 and phytochemicals as its modulator. We explored Science Direct, Scopus, and PubMed for a comprehensive literature review. Bibliometric and temporal trend analysis were done using VOSviewer.

RESULTS

Several phytochemicals can potentially alleviate neuroinflammation and oxidative stress-induced depressive symptoms. These effects result from inhibiting the MAPK and NK-κB pathways - both implicated in the overproduction of pro-inflammatory factors - and from the upregulation of HO-1 expression mediated by Nrf2. Bibliometric and temporal trend analysis further validates these associations.

CONCLUSION

In summary, our findings suggest that antidepressant agents can mitigate neuroinflammation and depressive disorder pathogenesis via the upregulation of HO-1 expression. These agents suppress pro-inflammatory mediators and depressive-like symptoms, demonstrating that HO-1 plays a significant role in the neuroinflammatory process and the development of depression.

Bakuchiol regulates TLR4/MyD88/NF-κB and Keap1/Nrf2/HO-1 pathways to protect against LPS-induced acute lung injury in vitro and in vivo

Bakuchiol (Bak) possesses a protective effect in acute lung injury (ALI). Nonetheless, the molecular processes that regulate the protective activity of Bak in ALI remain elusive. Lipopolysaccharide (LPS)-treated rats and RLE-6TN cells were used as the ALI models in vivo and in vitro to investigate the function and mechanism of Bak. Rats were divided into four groups: control, LPS, LPS + Bak (30 mg/kg), and LPS + Bak (60 mg/kg). RLE-6TN cells were assigned into four groups: control, LPS, LPS + Bak (10 µM), and LPS + Bak (20 µM). Myeloperoxidase (MPO) and 4-hydroxy-2-nonenal (4-HNE) levels were detected by immunohistochemistry (IHC). The levels of TNF-α, IL-6, and IL-1β were quantified by ELISA. Apoptosis was analyzed by TdT-mediated dUTP nick-end labeling (TUNEL) staining and flow cytometry. Malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and reactive oxygen species (ROS) were assayed to evaluate oxidative stress. In LPS-induced rats, Bak attenuated pathological injury, lung wet/dry weight ratio, MPO expression, and protein concentration and cell number in bronchial alveolar lavage fluid (BALF). Bak decreased the secretion of TNF-α, IL-6, and IL-1β in BALF. Bak reduced MDA content and 4-HNE expression, and increased SOD and GSH-Px activities in lung tissues. Bak also repressed pulmonary apoptosis by decreasing Bax expression and enhancing Bcl-2 expression. In LPS-treated RLE-6TN cells, Bak downregulated the mRNA levels of TNF-α, IL-6, and IL-1β and inhibited the protein expression of iNOS and COX2. Bak decreased MDA level and ROS production and increased SOD and GSH-Px activities. Bak also suppressed cell apoptosis, reduced Bax expression, and increased Bcl-2 expression. Moreover, Bak decreased the expression of TLR4, MyD88, p-IκBα, and p-p65. Additionally, Bak inhibited Keap1 expression and increased Nrf2 and HO-1 levels. Bak protects against LPS-induced inflammation, oxidative stress, and apoptosis in ALI by regulating TLR4/MyD88/NF-κB and Keap1/Nrf2/HO-1 pathways.

HH-A, a modified honokiol, protects against cerebral ischemia/reperfusion induced brain injury in rodent via Nrf2/HO-1 signaling pathways

Honokiol, a bioactive component found in Magnolia officinalis, has shown in protecting against ischemic stroke in animal models. However, its poor water solubility has limited its clinical applications. In this study, we introduced a hydrophilic building block on the aromatic ring of honokiol, resulting in the synthesis of four new compounds (HH-A, -B, -C and -D) with significantly improved water solubility. We then investigated the neuroprotective effects of these compounds in mouse and rat models of transient middle cerebral artery occlusion/reperfusion (tMCAO/R) brain injury. Among the compounds tested, HH-A, also known as (S)-6-((3',5-diallyl-2,4'-dihydroxy-[1,1'-biphenyl]-3-yl)amino)-6-oxohexane-1,5-diaminium chloride, showed the most promising results. HH-A was found to significantly reduced the infarct volume and brain edema in mice. It also outperformed the other three compounds and honokiol, even surpassing the effects of edaravone dexborneol. Additionally, HH-A demonstrated dose-dependent improvements in body weight, neurological deficits, and infarct volume. Further analysis in tMCAO/R rat model revealed that HH-A treatment led to significant upregulations of Nrf2 and HO-1 in the brain. HH-A also significantly reduced the expression of HNE, and exhibited anti-apoptotic effects by decreasing the expression of Bax and increasing the expression of Bcl-2. This was further supported by a decrease in the number of TUNEL positive cells. Taken together, the neuroprotective effects of HH-A may be attributed to its ability to target the Nrf2/HO-1 signaling pathway, leading to reduced oxidative stress and apoptosis in the brain. These findings suggest that HH-A has potential as a therapeutic agent for the treatment of ischemic stroke.

The clinical relevance of heme detoxification by the macrophage heme oxygenase system

Heme degradation by the heme oxygenase (HMOX) family of enzymes is critical for maintaining homeostasis and limiting heme-induced tissue damage. Macrophages express HMOX1 and 2 and are critical sites of heme degradation in healthy and diseased states. Here we review the functions of the macrophage heme oxygenase system and its clinical relevance in discrete groups of pathologies where heme has been demonstrated to play a driving role. HMOX1 function in macrophages is essential for limiting oxidative tissue damage in both acute and chronic hemolytic disorders. By degrading pro-inflammatory heme and releasing anti-inflammatory molecules such as carbon monoxide, HMOX1 fine-tunes the acute inflammatory response with consequences for disorders of hyperinflammation such as sepsis. We then discuss divergent beneficial and pathological roles for HMOX1 in disorders such as atherosclerosis and metabolic syndrome, where activation of the HMOX system sits at the crossroads of chronic low-grade inflammation and oxidative stress. Finally, we highlight the emerging role for HMOX1 in regulating macrophage cell death via the iron- and oxidation-dependent form of cell death, ferroptosis. In summary, the importance of heme clearance by macrophages is an active area of investigation with relevance for therapeutic intervention in a diverse array of human diseases.

Unraveling the Interplay of Dopamine, Carbon Monoxide, and Heme Oxygenase in Neuromodulation and Cognition

The dopaminergic system plays important roles in neuromodulation, including prominent roles in complex neurological functions such as cognition, reward, motivation, and memory. Understandably, the highly complex nature of such physiological functions means that their regulation is intertwined with other signaling pathways, as has been demonstrated by numerous studies. Contrary to its public perception of being poisonous at all concentrations, carbon monoxide (CO) is produced endogenously from heme degradation by heme oxygenase (HO) as part of the physiological process of red blood cell turnover. Physiological concentrations of CO can reach high micromolar ranges in the hemoglobin bound form. Low-dose CO has shown therapeutic effects in numerous animal models, including traumatic brain injury via engaging various hemoprotein targets. As such, the HO-CO axis has been shown to offer beneficial effects in organ protection, anti-inflammation, and neuroprotection, among many others. Further, a large number of publications have shown the interactions among CO, HO, and the dopaminergic system. In this review, we critically examine such experimental evidence in a holistic fashion and in the context of a possible dopamine-HO-CO signaling axis. We hope that this Perspective will stimulate additional investigations into the molecular connectivity related to this possible axis and open doors to the development of novel therapeutics that impact the dopaminergic system.

Tanshinone IIA regulates CCl4 induced liver fibrosis in C57BL/6J mice via the PI3K/Akt and Nrf2/HO-1 signaling pathways

Chronic liver diseases caused by various factors may develop into liver fibrosis (LF). Early stage of LF could be reversible. Tanshinone IIA (Tan IIA), an extract from Salvia miltiorrhiza, has been reported to be hepatoprotective. However, the potential targets and mechanism of Tan IIA in the treatment of LF are still unclear. Our study aims at the anti-LF mechanism of Tan IIA through network pharmacological analysis combined with LF-related experiments. Serum biochemical indicators and histopathological examination showed that Tan IIA could ameliorate the process of LF in the CCl4 -induced mouse model. Western blot and immunohistochemical assays showed that Tan IIA decreased the expression of Kirsten rat sarcoma viral oncogene homolog (KRAS), phosphatidylinositide 3-kinases/protein kinase B (PI3K/Akt), and nuclear factor erythroid 2-related factor/heme oxygenase-1 (Nrf2/HO-1). Compared with the model group, the Tan IIA groups increased the decreased superoxide dismutase activity and glutathione content, while decreasing the increased malondialdehyde content. These results indicate that Tan IIA may play an antioxidant role by inhibiting the expression of KRAS, PI3K/Akt, and Nrf2/HO-1 to ameliorate the progression of LF, which to some extent explains the pharmacological mechanism of Tan IIA in LF. In conclusion, our study demonstrates that Tan IIA could regulate LF via PI3K/Akt and Nrf2/HO-1 signaling pathways. It may be an effective therapeutic compound for the treatment of LF.

Quercetin attenuates cerebral ischemic injury by inhibiting ferroptosis via Nrf2/HO-1 signaling pathway

AIMS

Ischemic stroke is a severe cerebrovascular disease in which neuronal death continually occurs through multiple forms, including apoptosis, autophagy, pyroptosis and ferroptosis. Quercetin (QRC), as a natural flavonoid compound, has been reported to have pharmacological effects on ischemic injury accompanied by unclear anti-ferroptotic mechanisms. This study is designed to investigate the therapeutic effects of QRC against ferroptosis in ischemic stroke.

MATERIALS AND METHODS

In vivo, the model of MCAO rats were used to assess the protective effect of QRC on cerebral ischemic. Additionally, we constructed oxidative stressed and ferroptotic cell models to explore the effects and mechanisms of QRC on ferroptosis. The related proteins were analysed by western blotting, immunohistochemical and immunofluorescence techniques.

RESULTS

The experiments demonstrated that QRC improves neurological deficits, infarct volume, and pathological features in MCAO rats, also increased the viability of HT-22 cells exposed to H2O2 and erastin. These results, including MDA, SOD, GSH, ROS levels and iron accumulation, indicated that QRC suppresses the generation of lipid peroxides and may involve in the regulatory of ferroptosis. Both in vitro and in vivo, QRC was found to inhibit ferroptosis by up-regulating GPX4 and FTH1, as well as down-regulating ACSL4. Furthermore, we observed that QRC enhances the nuclear translocation of Nrf2 and activates the downstream antioxidative proteins. Importantly, the effect of QRC on ferroptosis can be reversed by the Nrf2 inhibitor ML385.

CONCLUSIONS

This study provides evidence that QRC has a neuroprotective effect by inhibiting ferroptosis, demonstrating the therapeutic potential for cerebral ischemic stroke.

Olanzapine alters the expression of gasotransmitter-related enzymes: CBS and HO-2 in the rat hippocampus and striatum

BACKGROUND

Gaseous neurotransmitters have been thought to be novel factors involved in the mechanisms of mental disorders pathogenesis for quite some time. However, little is known about the potential crosstalk between neuronal gasotransmitter signaling and neuroleptics action. The present work was, therefore, focused on gene expression of H2S and CO-producing enzymes in the brains of rats chronically treated with olanzapine, an atypical antipsychotic drug.

METHODS

Studies were carried out on adult, male Sprague-Dawley rats that were divided into 2 groups: control and experimental animals treated with olanzapine (28-day-long intraperitoneal injection, at a dose of 5 mg/kg daily). All individuals were sacrificed under anesthesia and the whole brains excised. Immunohistochemical procedure was used for histological assessment of the whole brain and for quantitative analysis of cystathionine β-synthase (CBS) and heme oxygenase 2 (HO-2) protein distribution in selected brain structures.

RESULTS

Long-term treatment with olanzapine is reflected in different changes in the number of enzymes-expressing cells in the rat brain. Olanzapine decreased the number of CBS-expressing cells and possibly reduced H2S synthesis in the hippocampus and striatum. The antipsychotic administration increased the number of HO-2 immunopositive cells and probably stimulated the CO production in the hippocampus.

CONCLUSIONS

Modulatory effect of olanzapine on cellular mechanisms of gasotransmitter synthesis may be an alternative way of their pharmacological action.

Biliverdin as a disease-modifying agent: An integrated viewpoint

Biliverdin is one of the three by-products of heme oxygenase (HO) activity, the others being ferrous iron and carbon monoxide. Under physiological conditions, once formed in the cell, BV is reduced to bilirubin (BR) by the biliverdin reductase (BVR). However, if BVR is inhibited by either genetic variants, as occurs in the Inuit ethnicity, or dioxin intoxication, BV accumulates in cells giving rise to a clinical syndrome known as green jaundice. Preclinical studies have demonstrated that BV not only has a direct antioxidant effect by scavenging free radicals, but also targets many signal transduction pathways, such as BVR, soluble guanylyl cyclase, and the aryl hydrocarbon receptor. Through these direct and indirect mechanisms, BV has shown beneficial roles in ischemia/reperfusion-related diseases, inflammatory diseases, graft-versus-host disease, viral infections and cancer. Unfortunately, no clinical data are available to confirm these potential therapeutic effects and the kinetics of exogenous BV in humans is unknown. These limitations have so far excluded the possibility of transforming BV from a mere by-product of heme degradation into a disease-modifying agent. A closer collaboration between basic and clinical researchers would be advantageous to overcome these issues and promote translational research on BV in free radical-induced diseases.

Co-administration of angiotensin II and simvastatin triggers kidney injury upon heme oxygenase-1 deficiency

Kidneys are pivotal organ in iron redistribution and can be severely damaged in the course of hemolysis. In our previous studies, we observed that induction of hypertension with angiotensin II (Ang II) combined with simvastatin administration results in a high mortality rate or the appearance of signs of kidney failure in heme oxygenase-1 knockout (HO-1 KO) mice. Here, we aimed to address the mechanisms underlying this effect, focusing on heme and iron metabolism. We show that HO-1 deficiency leads to iron accumulation in the renal cortex. Higher mortality of Ang II and simvastatin-treated HO-1 KO mice coincides with increased iron accumulation and the upregulation of mucin-1 in the proximal convoluted tubules. In vitro studies showed that mucin-1 hampers heme- and iron-related oxidative stress through the sialic acid residues. In parallel, knock-down of HO-1 induces the glutathione pathway in an NRF2-depedent manner, which likely protects against heme-induced toxicity. To sum up, we showed that heme degradation during heme overload is not solely dependent on HO-1 enzymatic activity, but can be modulated by the glutathione pathway. We also identified mucin-1 as a novel redox regulator. The results suggest that hypertensive patients with less active HMOX1 alleles may be at higher risk of kidney injury after statin treatment.

Altered Expression of Heme Oxygenase 2 in Heme Oxygenase 1-deficient Mouse Embryos

Heme oxygenases (Hmoxs) are enzymes that catalyze the first and rate-limiting step in the degradation of heme to carbon monoxide, iron, and biliverdin. The two main isozymes, namely Hmox1 and Hmox2, are encoded by two different genes. Mutation of the Hmox1 gene in mice is known to cause extensive prenatal lethality, and limited information is available about the expression of Hmox proteins in developing mouse embryos. In this study, immunohistochemistry was used to perform a detailed investigation comparing Hmox proteins in Hmox1 wild-type and knockout (KO) mouse embryos collected from wild-type and heterozygous timed-matings. Western analysis for Hmoxs was also done in the organs of late-gestation embryos. The results demonstrated cytoplasmic and nuclear localization of Hmoxs in all the organs examined in wild-type embryos. Interestingly, Hmox2 immunoreactive protein signals were significantly low in most of the organs of mid- and late-gestation Hmox1-KO embryos. Furthermore, relative levels of Hmox2 were revealed to be significantly lower in the lung and kidney of late-gestation Hmox1-KO embryos by western analysis, which complemented the immunohistochemistry findings in these two organs. The current study provides detailed immunoexpression patterns of Hmox proteins in wild-type and Hmox1-KO mouse embryos in mid- and late-gestation.

Acacetin alleviates myocardial ischaemia/reperfusion injury by inhibiting oxidative stress and apoptosis via the Nrf-2/HO-1 pathway

CONTEXT

Acacetin is a natural source of flavonoids with anti-inflammatory and antioxidant effects.

OBJECTIVE

This study determines acacetin's protective effect and mechanism on myocardial ischaemia/reperfusion (I/R) injury.

MATERIALS AND METHODS

Sprague-Dawley rats were divided into sham and I/R injury and treatment with acacetin. Acacetin (10 mg/kg) was subcutaneously injected for 7 days. ECG and echocardiography were conducted to determine arrhythmia and heart function. The pathological characters of the heart were determined with triphenyl tetrazolium chloride staining, Haematoxylin & Eosin staining, and Masson staining. Expression of proteins in infarct tissues was examined with western blots.

RESULTS

Administrated with acacetin in I/R rats significantly reduced the arrhythmia score from 4.90 to 2.50 and the reperfusion arrhythmia score from 3.79 to 1.82 in the vehicle or the acacetin group, respectively. LVEF was improved from 33.5% in the I/R group to 43.7% in the acacetin group, LVFS was increased from 16.4% to 24.5%, LVIDs was decreased from 6.5 to 5.3 mm. The inflammatory cell infiltration, myocardial fibrosis, and collagen 1 and 3 were reduced by acacetin. Acacetin promoted SOD and decreased MDA. In myocardial tissues, the expression level of TLR4 and IL-6 were restrained, and IL-10 was promoted. Apoptotic protein Bax was suppressed, and anti-apoptotic protein Bcl-2 was promoted in the acacetin group. Interestingly, the transcription factor Nrf-2/HO-1 pathway was also reversed by acacetin.

DISCUSSION AND CONCLUSION

Our findings indicated that acacetin has a potential therapeutic effect in clinical application on treating I/R-induced heart injury.

Heme delivery to heme oxygenase-2 involves glyceraldehyde-3-phosphate dehydrogenase

Heme regulatory motifs (HRMs) are found in a variety of proteins with diverse biological functions. In heme oxygenase-2 (HO2), heme binds to the HRMs and is readily transferred to the catalytic site in the core of the protein. To further define this heme transfer mechanism, we evaluated the ability of GAPDH, a known heme chaperone, to transfer heme to the HRMs and/or the catalytic core of HO2. Our results indicate GAPDH and HO2 form a complex in vitro. We have followed heme insertion at both sites by fluorescence quenching in HEK293 cells with HO2 reporter constructs. Upon mutation of residues essential for heme binding at each site in our reporter construct, we found that HO2 binds heme at the core and the HRMs in live cells and that heme delivery to HO2 is dependent on the presence of GAPDH that is competent for heme binding. In sum, GAPDH is involved in heme delivery to HO2 but, surprisingly, not to a specific site on HO2. Our results thus emphasize the importance of heme binding to both the core and the HRMs and the interplay of HO2 with the heme pool via GAPDH to maintain cellular heme homeostasis.

Heme Oxygenase-1 as Therapeutic Target for Diabetic Foot Ulcers

A diabetic foot ulcer (DFU) is one of the major complications of diabetes. Wound healing under diabetic conditions is often impaired. This is in part due to the excessive oxidative stress, prolonged inflammation, immune cell dysfunction, delayed re-epithelialization, and decreased angiogenesis present at the wound site. As a result of these multifactorial impaired healing pathways, it has been difficult to develop effective therapeutic strategies for DFU. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme in heme degradation generating carbon monoxide (CO), biliverdin (BV) which is converted into bilirubin (BR), and iron. HO-1 is a potent antioxidant. It can act as an anti-inflammatory, proliferative, angiogenic and cytoprotective enzyme. Due to its biological functions, HO-1 plays a very important role in wound healing, in part mediated through the biologically active end products generated by its enzymatic activity, particularly CO, BV, and BR. Therapeutic strategies involving the activation of HO-1, or the topical application of its biologically active end products are important in diabetic wound healing. Therefore, HO-1 is an attractive therapeutic target for DFU treatment. This review will provide an overview and discussion of the importance of HO-1 as a therapeutic target for diabetic wound healing.

Silencing the Adipocytokine NOV: A Novel Approach to Reversing Oxidative Stress-Induced Cardiometabolic Dysfunction

Objective: NOV/CCN3 is an adipocytokine recently linked to obesity, insulin resistance, and cardiometabolic dysfunction. NOV is manufactured and secreted from adipose tissue, with blood levels highly correlated with BMI. NOV levels are increased in obesity and a myriad of inflammatory diseases. Elevated NOV levels cause oxidative stress by increasing free radicals, decreasing antioxidants, and decreasing heme oxygenase (HO-1) levels, resulting in decreased vascular function. Silencing NOV in NOV knockout mice improved insulin sensitivity. We wanted to study how suppressing NOV expression in an obese animal model affected pathways and processes related to obesity, inflammation, and cardiometabolic function. This is the first study to investigate the interaction of adipose tissue-specific NOV/CCN3 and cardiometabolic function. Methods: We constructed a lentivirus containing the adiponectin-promoter-driven shNOV to examine the effect of NOV inhibition (shNOV) in adipose tissue on the heart of mice fed a high-fat diet. Mice were randomly divided into three groups (five per group): (1) lean (normal diet), (2) high-fat diet (HFD)+ sham virus, and (3) HFD + shNOV lentivirus. Blood pressure, tissue inflammation, and oxygen consumption were measured. Metabolic and mitochondrial markers were studied in fat and heart tissues. Results: Mice fed an HFD developed adipocyte hypertrophy, fibrosis, inflammation, and decreased mitochondrial respiration. Inhibiting NOV expression in the adipose tissue of obese mice by shNOV increased mitochondrial markers for biogenesis (PGC-1α, the nuclear co-activator of HO-1) and functional integrity (FIS1) and insulin signaling (AKT). The upregulation of metabolic and mitochondrial markers was also evident in the hearts of the shNOV mice with the activation of mitophagy. Using RNA arrays, we identified a subgroup of genes that highly correlated with increased adipocyte mitochondrial autophagy in shNOV-treated mice. A heat map analysis in obese mice confirmed that the suppression of NOV overrides the genetic susceptibility of adiposity and the associated detrimental metabolic changes and correlates with the restoration of anti-inflammatory, thermogenic, and mitochondrial genes. Conclusion: Our novel findings demonstrate that inhibiting NOV expression improves adipose tissue function in a positive way in cardiometabolic function by inducing mitophagy and improving mitochondrial function by the upregulation of PGC-1α, the insulin sensitivity signaling protein. Inhibiting NOV expression increases PGC-1, a key component of cardiac bioenergetics, as well as key signaling components of metabolic change, resulting in improved glucose tolerance, improved mitochondrial function, and decreased inflammation. These metabolic changes resulted in increased oxygen consumption, decreased adipocyte size, and improved cardiac metabolism and vascular function at the structural level. The crosstalk of the adipose tissue-specific deletion of NOV/CCN3 improved cardiovascular function, representing a novel therapeutic strategy for obesity-related cardiometabolic dysfunction.

BACH1-Hemoxygenase-1 axis regulates cellular energetics and survival following sepsis

Sepsis is a complex disease due to dysregulated host response to infection. Oxidative stress and mitochondrial dysfunction leading to metabolic dysregulation are among the hallmarks of sepsis. The transcription factor NRF2 (Nuclear Factor E2-related factor2) is a master regulator of the oxidative stress response, and the NRF2 mediated antioxidant response is negatively regulated by BTB and CNC homology 1 (BACH1) protein. This study tested whether Bach1 deletion improves organ function and survival following polymicrobial sepsis induced by cecal ligation and puncture (CLP). We observed enhanced post-CLP survival in Bach1-/- mice with a concomitantly increased liver HO-1 expression, reduced liver injury and oxidative stress, and attenuated systemic and tissue inflammation. After sepsis induction, the liver mitochondrial function was better preserved in Bach1-/- mice. Furthermore, BACH1 deficiency improved liver and lung blood flow in septic mice, as measured by SPECT/CT. RNA-seq analysis identified 44 genes significantly altered in Bach1-/- mice after sepsis, including HMOX1 and several genes in lipid metabolism. Inhibiting HO-1 activity by Zinc Protoporphyrin-9 worsened organ function in Bach1-/- mice following sepsis. We demonstrate that mitochondrial bioenergetics, organ function, and survival following experimental sepsis were improved in Bach1-/- mice through the HO-1-dependent mechanism and conclude that BACH1 is a therapeutic target in sepsis.

Counteraction of Myocardial Ferritin Heavy Chain Deficiency by Heme Oxygenase-1

Given the abundance of heme proteins (cytochromes) in the mitochondrion, it is evident that a meticulously orchestrated iron metabolism is essential for cardiac health. Here, we examined the functional significance of myocardial ferritin heavy chain (FtH) in a model of acute myocardial infarction. We report that FtH deletion did not alter either the mitochondrial regulatory and surveillance pathways (fission and fusion) or mitochondrial bioenergetics in response to injury. Furthermore, deletion of myocardial FtH did not affect cardiac function, assessed by measurement of left ventricular ejection fraction, on days 1, 7, and 21 post injury. To identify the modulated pathways providing cardiomyocyte protection coincident with FtH deletion, we performed unbiased transcriptomic analysis. We found that following injury, FtH deletion was associated with upregulation of several genes with anti-ferroptotic properties, including heme oxygenase-1 (HO-1) and the cystine/glutamate anti-porter (Slc7a11). These results suggested that HO-1 overexpression mitigates ferroptosis via upregulation of Slc7a11. Indeed, using transgenic mice with HO-1 overexpression, we demonstrate that overexpressed HO-1 is coupled with increased Slc7a11 expression. In conclusion, we demonstrate that following injury, myocardial FtH deletion leads to a compensatory upregulation in a number of anti-ferroptotic genes, including HO-1. Such HO-1 induction leads to overexpression of Slc7a11 and protects the heart against ischemia-reperfusion-mediated ferroptosis, preserves mitochondrial function, and overall function of the myocardium.

[Efficient production of biliverdin through whole-cell biocatalysis using recombinant Escherichia coli]

Biliverdin is an important cellular antioxidant. Traditionally, biliverdin is produced by chemical oxidation of bilirubin, which is a complex process and the final product is of low purity. Here we report an efficient, green and safe process for biotechnological production of biliverdin. A heme oxygenase (HO) gene from Clostridium tetani was screened, and a recombinant strain Escherichia coli BL21/pETDuet-hoCt with the ability of transforming heme into biliverdin was constructed. A biliverdin yield of 32.9 mg/L from 100 mg/L substrate was achieved under pH 7.0 and 35 ℃. In order to improve the supply of reducing power, an NADPH regeneration system using glutamate dehydrogenase (GdhA) was constructed, resulting in a recombinant strain E. coli BL21/pETDuet-gdhAEc-hoCt which was capable of producing 71.5 mg/L biliverdin. Moreover, through introduction of a membrane surface display system, a recombinant strain E. coli BL21/pETDuet-gdhAEc-blc/hoCt was constructed to shorten the transformation time, and the production of biliverdin was further increased to 76.3 mg/L, this is the highest titer of biosynthesized biliverdin reported to date, and the research may thus facilitate the green production of biliverdin.

Itaconate Suppresses Formation of Neutrophil Extracellular Traps (NETs): Involvement of Hypoxia-Inducible Factor 1α (Hif-1α) and Heme Oxygenase (HO-1)

Neutrophil extracellular traps (NETs) immobilize pathogens during early stages of systemic inflammation but as the reaction progresses they become detrimental to endothelial cells and the organ-specific cells. For this reason it would be of importance to control their formation by either physiological or pharmacological means. Endogenously, formation of NETs is under control of cellular and whole organism metabolism as shown previously in the course of bacterial systemic inflammation, obesity or the combination of the two. Numerous leukocytes are subjected to immunometabolic regulation and in macrophages exposure to lipopolysaccharide (LPS) leads to two breaks in the Krebs cycle that impact this cell functioning. As a consequence of the first break, anti-microbial itaconic acid (itaconate) is produced whereas the second break activates hypoxia-inducible factor-1α (Hif-1α). In turn, itaconate activates transcription of the anti-inflammatory nuclear factor erythroid 2-related factor 2 (Nrf2) which upregulates cyto-protective heme oxygenase (HO-1). Here we report that exogenously added derivative of the itaconic acid, 4-octyl itaconate (4-OI), diminishes formation of NETs by neutrophils of either normal (lean) or obese mice, and independently of the age of the animals or immunoaging. Elucidating the mechanism of this inhibition we unravel that although Nrf2/HO-1 expression itself is not altered by 4-OI, it is up-regulated when compared against the NET formation while Hif-1α is downregulated in 4-OI-pre-treated LPS-stimulated neutrophils in either way. We further show that blockage of Hif-1α by its specific inhibitor diminishes NET release as does inhibition by 4-OI. Also inhibition of HO-1 activity correlates with diminished LPS-induced NET release upon pre-treatment with 4-OI albeit LPS alone induced NETs are not HO-1-dependent. In summary, we unravel that 4-OI inhibits NET formation by murine neutrophils independently of their origin (health vs. metabolically challenged animals) and the age of individuals/immunosenescence via inhibition of Hif-1α and induction of HO-1.

Beneficial and Detrimental Roles of Heme Oxygenase-1 in the Neurovascular System

Heme oxygenase (HO) has both beneficial and detrimental effects via its metabolites, including carbon monoxide (CO), biliverdin or bilirubin, and ferrous iron. HO-1 is an inducible form of HO that is upregulated by oxidative stress, nitric oxide, CO, and hypoxia, whereas HO-2 is a constitutive form that regulates vascular tone and homeostasis. In brains injured by trauma, ischemia-reperfusion, or Alzheimer’s disease (AD), the long-term expression of HO-1 can be detected, which can lead to cytotoxic ferroptosis via iron accumulation. In contrast, the transient induction of HO-1 in the peri-injured region may have regenerative potential (e.g., angiogenesis, neurogenesis, and mitochondrial biogenesis) and neurovascular protective effects through the CO-mediated signaling pathway, the antioxidant properties of bilirubin, and the iron-mediated ferritin synthesis. In this review, we discuss the dual roles of HO-1 and its metabolites in various neurovascular diseases, including age-related macular degeneration, ischemia-reperfusion injury, traumatic brain injury, Gilbert’s syndrome, and AD.

Protective Effects of Amauroderma rugosum on Doxorubicin-Induced Cardiotoxicity through Suppressing Oxidative Stress, Mitochondrial Dysfunction, Apoptosis, and Activating Akt/mTOR and Nrf2/HO-1 Signaling Pathways

Clinical outcomes for doxorubicin (Dox) are limited by its cardiotoxicity but a combination of Dox and agents with cardioprotective activities is an effective strategy to improve its therapeutic outcome. Natural products provide abundant resources to search for novel cardioprotective agents. Ganoderma lucidum (GL) is the most well-known edible mushroom within the Ganodermataceae family. It is commonly used in traditional Chinese medicine or as a healthcare product. Amauroderma rugosum (AR) is another genus of mushroom from the Ganodermataceae family, but its pharmacological activity and medicinal value have rarely been reported. In the present study, the cardioprotective effects of the AR water extract against Dox-induced cardiotoxicity were studied in vitro and in vivo. Results showed that both the AR and GL extracts could potentiate the anticancer effect of Dox. The AR extract significantly decreased the oxidative stress, mitochondrial dysfunction, and apoptosis seen in Dox-treated H9c2 rat cardiomyocytes. However, knockdown of Nrf2 by siRNA abolished the protective effects of AR in these cells. In addition, Dox upregulated the expression of proapoptotic proteins and downregulated the Akt/mTOR and Nrf2/HO-1 signaling pathways, and these effects could be reversed by the AR extract. Consistently, the AR extract significantly prolonged survival time, reversed weight loss, and reduced cardiac dysfunction in Dox-treated mice. In addition, oxidative stress and apoptosis were suppressed, while Nrf2 and HO-1 expressions were elevated in the heart tissues of Dox-treated mice after treatment with the AR extract. However, the GL extract had less cardioprotective effect against Dox in both the cell and animal models. In conclusion, the AR water extract demonstrated a remarkable cardioprotective effect against Dox-induced cardiotoxicity. One of the possible mechanisms for this effect was the upregulation of the mTOR/Akt and Nrf2/HO-1-dependent pathways, which may reduce oxidative stress, mitochondrial dysfunction, and cardiomyocyte apoptosis. These findings suggested that AR may be beneficial for the heart, especially in patients receiving Dox-based chemotherapy.

Heme Oxygenase Modulation Drives Ferroptosis in TNBC Cells

The term ferroptosis refers to a peculiar type of programmed cell death (PCD) mainly characterized by extensive iron-dependent lipid peroxidation. Recently, ferroptosis has been suggested as a potential new strategy for the treatment of several cancers, including breast cancer (BC). In particular, among the BC subtypes, triple negative breast cancer (TNBC) is considered the most aggressive, and conventional drugs fail to provide long-term efficacy. In this context, our study's purpose was to investigate the mechanism of ferroptosis in breast cancer cell lines and reveal the significance of heme oxygenase (HO) modulation in the process, providing new biochemical approaches. HO's effect on BC was evaluated by MTT tests, gene silencing, Western blot analysis, and measurement of reactive oxygen species (ROS), glutathione (GSH) and lipid hydroperoxide (LOOH) levels. In order to assess HO's implication, different approaches were exploited, using two distinct HO-1 inducers (hemin and curcumin), a well-known HO inhibitor (SnMP) and a selective HO-2 inhibitor. The data obtained showed HO's contribution to the onset of ferroptosis; in particular, HO-1 induction seemed to accelerate the process. Moreover, our results suggest a potential role of HO-2 in erastin-induced ferroptosis. In view of the above, HO modulation in ferroptosis can offer a novel approach for breast cancer treatment.

Administration of hemin ameliorates ovarian ischemia reperfusion injury via modulation of heme oxygenase-1 and p-JNK/p-NF-κBp65/iNOS signaling pathway

AIMS

Ovarian torsion is the fifth common gynecological emergency that can affect females of all ages particularly during reproductive age and its management by detorsion leads to ovarian ischemia reperfusion (IR) injury. Therefore, prophylactic measures are required to protect the ovarian function after detorsion. So that, our study aimed to assess the effect and underlying mechanisms of heme oxygenase-1 (HO-1) inducer; hemin against ovarian damage induced by IR injury in rats.

MAIN METHODS

Female rats were divided into: sham group, hemin group, ovarian IR (OIR) groups with and without hemin treatment. Serum levels of reduced glutathione (GSH) and interleukin 1 β (IL-1β) were measured in addition to ovarian levels of malondialdehyde (MDA), nitric oxide (NO) and superoxide dismutase (SOD). Ovarian phospho-Janus kinase (p-JNK) levels and gene expressions of HO-1 and inducible nitric oxide synthase (iNOS) were determined. Moreover, histopathological changes and expressions of phospho-nuclear factor kappa B p65 (p-NF-κB p65) and cleaved caspase-3 were done.

KEY FINDINGS

Treatment of OIR rats with hemin led to significant attenuation of ovarian damage through histological examination which was associated with significant increase in ovarian expression of HO-1, ovarian SOD and serum GSH levels with significant decrease in ovarian p-JNK levels, expressions of p-NF-κB p65, iNOS and cleaved caspase-3 in addition to serum IL-1β levels.

SIGNIFICANCE

The protective effect of hemin can be attributed to the increased expression of HO-1 which showed antioxidant, anti-inflammatory and anti-apoptotic effects. Therefore, hemin can be administered to prevent ovarian IR injury which occurs after detorsion.

Road to the discovery of HO-2's myristate binding activity

We discovered an unexpected new activity of a well-studied enzyme, heme oxygenase 2 (HO-2)-proof that an old dog can learn new tricks.

Protective effect of tin chloride on rhabdomyolysis-induced acute kidney injury in rats

The heme component of myoglobin plays a crucial role in the pathogenesis of rhabdomyolysis-associated acute kidney injury (RM-AKI). Heme oxiganenase-1 (HO-1) is the rate-limiting enzyme of heme catabolism, and its metabolites, iron, biliverdin, and carbon monoxide, have antioxidant properties. Tin chloride (SnCl₂) is a kidney specific HO-1 inducer. In this study, we examined whether the induction of HO-1 in the kidney by SnCl_₂ pretreatment ameliorates RM-AKI in rats and if the effect is due to the degradation of excess renal free heme. We developed an RM-AKI rat (male Sprague-Dawley rats) model by injecting glycerol (Gly) in the hind limbs. RM-AKI rats were pretreated with saline or SnCl_₂ or additional SnMP (tin mesoporphyrin, a specific HO inhibitor) followed by Gly treatment. Serum blood urea nitrogen (BUN) and creatinine (Crea) were measured as indicators of renal function. Renal free heme level was assessed based on the levels of δ-aminolevulinate synthase (ALAS1), a heme biosynthetic enzyme, and nuclear BTB and CNC homology 1 (Bach1), an inhibitory transcription factor of HO-1. Elevated free heme levels lead to decreases in ALAS1 and nuclear Bach1. After 24 h of Gly injection, serum BUN and Crea levels in saline-pretreated rats were significantly higher than those in untreated control rats. In contrast, SnCl_₂-pretreated rats showed no significant increase in the indices. However, additional treatment of SnMP abolished the beneficial effect of SnCl_₂. Renal ALAS1 mRNA levels and renal nuclear Bach1 protein levels in the saline pretreated rats were significantly lower than those in control rats 3 h after Gly injection. In contrast, the levels in SnCl₂-pretreated rats were not altered. The findings indicate that SnCl₂ pretreatment confers protection against RM-AKI by virtue of HO-1 induction in the renal system, at least in part through excess free heme degradation.

Heme oxygenase-nitric oxide crosstalk-mediated iron homeostasis in plants under oxidative stress

Plant growth under abiotic stress conditions significantly enhances intracellular generation of reactive oxygen species (ROS). Oxidative status of plant cells is directly affected by the modulation of iron homeostasis. Among mammals and plants, heme oxygenase-1 (HO-1) is a well-known antioxidant enzyme. It catalyzes oxygenation of heme, thereby producing Fe²⁺, CO and biliverdin as byproducts. The antioxidant potential of HO-1 is primarily due to its catalytic reaction byproducts. Biliverdin and bilirubin possess conjugated π-electrons which escalate the ability of these biomolecules to scavenge free radicals. CO also enhances the ROS scavenging ability of plants cells by upregulating catalase and peroxidase activity. Enhanced expression of HO-1 in plants under oxidative stress accompanies sequestration of iron in specialized iron storage proteins localized in plastids and mitochondria, namely ferritin for Fe³⁺ storage and frataxin for storage of Fe-S clusters, respectively. Nitric oxide (NO) crosstalks with HO-1 at multiple levels, more so in plants under oxidative stress, in order to maintain intracellular iron status. Formation of dinitrosyl-iron complexes (DNICs) significantly prevents Fenton reaction during oxidative stress. DNICs also release NO upon dissociation in target cells over long distance in plants. They also function as antioxidants against superoxide anions and lipidic free radicals. A number of NO-modulated transcription factors also facilitate iron homeostasis in plant cells. Plants facing oxidative stress exhibit modulation of lateral root formation by HO-1 through NO and auxin-dependent pathways. The present review provides an in-depth analysis of the structure-function relationship of HO-1 in plants and mammals, correlating them with their adaptive mechanisms of survival under stress.

Fluoxetine ameliorates Alzheimer's disease progression and prevents the exacerbation of cardiovascular dysfunction of socially isolated depressed rats through activation of Nrf2/HO-1 and hindering TLR4/NLRP3 inflammasome signaling pathway

Depression is a risk factor for Alzheimer's (AD) and cardiovascular diseases (CVD). Therefore, depression treatment restricts its deteriorating effects on mood, memory and CV system. Fluoxetine is the most widely used antidepressant drug, it has neuroprotective effect through its antioxidant/anti-inflammatory properties. The current study investigated for the first-time the cross link between depression, AD and CVD besides, role of fluoxetine in mitigating such disorders. Depression was induced in rats by social isolation (SI) for 12 weeks, AlCL3 (70 mg/kg/day, i.p.) was used to induce AD which was administered either in SI or normal control (NC) grouped rats starting at 8th week till the end of the experiment, fluoxetine (10 mg/kg/day, p.o) treatment also was started at 8th week. SI and AD showed a statistically significant deteriorated effect on behavioral, neurochemical and histopathological analysis which was exaggerated when two disorder combined than each alone. Fluoxetine treatment showed protective effect against SI, AD and prevents exacerbation of CVD. Fluoxetine improved animals' behavior, increased brain monoamines, BDNF besides increased antioxidant defense mechanism of SOD, TAC contents and increased protein expression of Nrf2/HO-1 with significant decrease of AChE activity, β-amyloid, Tau protein, MDA, TNF-α, IL1β contents as well as decreased protein expression of NF-kB, TLR4, NLRP3 and caspase1. It also showed cardioprotective effects as it improved lipid profile with pronounced decrease of cardiac enzymes of CK-MB, troponin and MEF2. In conclusion, fluoxetine represents as a promising drug against central and peripheral disorders through its anti-inflammatory/antioxidant effects via targeting antioxidant Nrf2/HO-1 and hindering TLR4/NLRP3 inflammasome signaling pathways.

Role of heme oxygenase in the regulation of the renal hemodynamics in a model of sex-dependent programmed hypertension by maternal diabetes

Intrauterine programming of cardiovascular and renal function occurs in diabetes because of the adverse maternal environment. Heme oxygenase 1 (HO-1) and -2 (HO-2) exert vasodilatory and antioxidant actions, particularly in conditions of elevated HO-1 expression or deficient nitric oxide levels. We evaluated whether the activity of the heme-HO system is differentially regulated by oxidative stress in the female offspring of diabetic mothers, contributing to the improved cardiovascular function in comparison with males. Diabetes was induced in pregnant rats by a single dose of streptozotocin (STZ, 50 mg/kg ip) in late gestation. Three-month-old male offspring from diabetic mothers (MODs) exhibited higher blood pressure (BP), higher renal vascular resistance (RVR), worse endothelium-dependent response to acetylcholine (ACH), and an increased constrictor response to phenylephrine (PHE) compared with those in age-matched female offspring of diabetic mothers (FODs), which were abolished by chronic tempol (1 mM) treatment. In anesthetized animals, stannous mesoporphyrin (SnMP; 40 µmol/kg iv) administration, to inhibit HO activity, increased RVR in FODs and reduced glomerular filtration rate (GFR) in MODs, without altering these parameters in control animals. When compared with MODs, FODs showed lower nitrotirosyne levels and higher HO-1 protein expression in renal homogenates. Indeed, chronic treatment with tempol in MODs prevented elevations in nitrotyrosine levels and the acute renal hemodynamics response to SnMP. Then, maternal diabetes results in sex-specific hypertension and renal alterations associated with oxidative stress mainly in adult male offspring, which are reduced in the female offspring by elevation in HO-1 expression and lower oxidative stress levels.

Effect of Ginsenoside Rh1 on Proliferation, Apoptosis, and Oxidative Stress in Vascular Endothelial Cells by Regulation of the Nuclear Erythroid 2-related Factor-2/Heme Oxygenase-1 Signaling Pathway

ABSTRACT

This study aimed to investigate the role of ginsenoside Rh1 in regulating the proliferation, apoptosis, and oxidative stress in oxidized low-density lipoprotein (ox-LDL)-treated human vascular endothelial cells (VECs) and the underlying mechanisms. VECs were treated with ox-LDL to generate an in vitro atherosclerosis model. The effect of ginsenoside Rh1 on cell viability and proliferation was examined by MTT and colony formation assays, respectively, and cell apoptosis was determined by flow cytometry and transferase dUTP nick end-labeling assay. The levels of reactive oxygen species, malondialdehyde, and superoxide dismutase activity were detected using biological assays. Finally, the effect of ginsenoside Rh1 on the levels of BAX and BCL-2 and the nuclear erythroid 2-related factor-2/heme oxygenase (HO)-1 signaling pathway was determined by quantitative real-time polymerase chain reaction and western blot assays. Treatment with ginsenoside Rh1 significantly increased the proliferation and decreased the apoptosis of ox-LDL-treated VECs in a dose-dependent manner. Moreover, ginsenoside Rh1 also relieved oxidative stress in ox-LDL-treated VECs by activating the Nrf2/HO-1 signaling pathway. Thus, ginsenoside Rh1 affects the proliferation, apoptosis, and oxidative stress in ox-LDL-treated VECs by activating the Nrf2/HO-1 signaling pathway.

Arjunolic acid from Cyclocarya paliurus ameliorates diabetic retinopathy through AMPK/mTOR/HO-1 regulated autophagy pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cyclocarya paliurus (CP) is a traditional Chinese herb and possesses a variety of biological activities including anti-hyperglycemia, anti-hyperlipidemia, antioxidant and anti-inflammation. Arjunolic acid (AA) is an abundant and bioactive ingredient in CP that shows significant protection against many metabolic diseases such as diabetic complication. Diabetic retinopathy (DR) is a serious complication of diabetes and may lead to vision loss. However, the protective effects and underlying mechanisms of AA against DR is not still understood.

AIM OF THE STUDY

We aimed to investigate whether AA activates AMPK/mTOR/HO-1 regulated autophagy pathway to alleviate DR.

MATERIALS AND METHODS

In the study, the STZ-induced diabetic model of rats was established, and AA with 10 and 30 mg/kg dosages was given orally for ten weeks to investigate their effect on retinal injury of DR. H₂O₂-induced ARPE-19 cells were applied to evaluate anti-apoptosis and anti-oxidant effect of AA.

RESULTS

The results revealed that AA could prevent STZ-induced weight loss and increase the retinal thickness and nuclei counts. The level of HO-1 protein was upregulated both in vivo and in vitro. In addition, AA prevented retinal damage and cell apoptosis through the AMPK-mTOR-regulated autophagy pathway. Furthermore, anti-apoptosis capacity, as well as the expression of HO-1 and LC3 protein, were effectively locked by AMPK inhibitor dorsomorphin dihydrochloride (compound C).

CONCLUSIONS

This finding implies that AA may be a promising candidate drug by protecting retinal cells from STZ-induced oxidative stress and inflammation through the AMPK/mTOR/HO-1 regulated autophagy pathway.

Extracellular vesicles derived from HBMSCs improved myocardial infarction through inhibiting zinc finger antisense 1 and activating Akt/Nrf2/HO-1 pathway

Myocardial infarction (MI) is believed to be one of the most common cardiovascular diseases, and it is seriously threatening the health of people in the world. The extracellular vesicles (EVs) isolated from mesenchymal stem cells and zinc finger antisense 1 (ZFAS1) have been believed to be involved in the regulation of MI, but the mechanism has not been fully clarified. Left anterior descending artery ligation was used to establish MI animal model, hypoxia treatment was applied to establish MI cell model. CCK8, transwell, and wound healing methods were applied to measure cell proliferation, invasion, and migration. Overexpression of ZFAS1 was established via transfecting pcDNA-ZFAS1. Overexpression of ZFAS1 significantly reversed the influence of EVs on cell migration, invasion, and apoptosis. Similar effect of EVs and ZFAS1 on morphological changes of MI rat heart tissues were also observed. The activation of Akt/Nrf2/HO-1 pathway by EVs was remarkably suppressed by pcDNA-ZFAS1. Inhibitor of Akt/Nrf2/HO-1 pathway remarkably reversed the impact of EVs on the cell viability. EVs might improve MI through inhibiting ZFAS1 and promoting Akt/Nrf2/HO-1 pathway. This study might provide a new thought for the prevention and treatment of MI damage through regulating ZFAS1 or Akt/Nrf2/HO-1 pathway.

Polyherbal Formulation Ameliorates Diabetic Cardiomyopathy Through Attenuation of Cardiac Inflammation and Oxidative Stress Via NF-κB/Nrf-2/HO-1 Pathway in Diabetic Rats

ABSTRACT

The present study was intended to evaluate the effect of polyherbal formulation (PHF) made with 3 nutraceuticals, such as Piper nigrum, Terminalia paniculata, and Bauhinia purpurea on inflammation and oxidative stress in diabetic cardiomyopathy (DCM), which is induced by streptozotocin and nicotinamide administration in rats. We supplemented DCM rats with PHF (250 and 500 mg/kg/BW) for 45 days and evaluated their effects on oxidative stress markers, proinflammatory cytokines, and messenger RNA expressions of the nuclear factor erythroid 2-related factor-2 (Nrf-2) and its linked genes [heme oxygenase-1 (HO-1), superoxide dismutase, catalase] along with inflammatory genes [tumour necrosis factor α and nuclear factor kappa B (NF-κB)]. Our study demonstrated that PHF successfully attenuated inflammation and oxidative stress via messenger RNA upregulation of Nrf-2, HO-1, superoxide dismutase, and catalase and concomitantly with downregulation of tumour necrosis factor α and NF-κB. Conversely, PHF also protected hyperglycemia-mediated cardiac damage, which was confirmed with histopathological and scanning electron microscopy analysis. In conclusion, our results suggested that PHF successfully ameliorated hyperglycemia-mediated inflammation and oxidative stress via regulation of NF-κB/Nrf-2/HO-1 pathway. Therefore, these results recommend that PHF may be a prospective therapeutic agent for DCM.

Propofol inhibits oxidative stress injury through the glycogen synthase kinase 3 beta/nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway

Oxidative stress is the main cause of ischemia/reperfusion injury. Propofol is a commonly used intravenous hypnotic anesthetic agent with antioxidant properties. In this study, we aimed to elucidate the protective effects of propofol on H2O2-induced cardiomyocyte injury and myocardial ischemic/reperfusion injury (MIRI) in rats. Cardiomyocyte injury was evaluated by determining cardiac troponin-1 (cTn-1) and creatine kinase-MB (CK-MB) levels. Antioxidative stress was assessed by measuring lactate dehydrogenase (LDH), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), reactive oxygen species (ROS), and catalase (CAT) levels. Apoptosis was evaluated using flow cytometry and TUNEL assays. Bax and Bcl-2 expression levels were determined by quantitative reverse transcription PCR (qRT-PCR) and Western blotting. The levels of glycogen synthase kinase 3 beta/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway-related factors were measured using Western blotting. Myocardial infarction in rats was analyzed using an Evans blue staining assay. The results showed that propofol reduced the levels of CK-MB, cTn-1, LDH, MDA, and ROS, and increased the levels of GSH, SOD, and CAT in H2O2-treated H9c2 cells. Additionally, propofol inhibited H2O2-induced apoptosis by downregulating Bax and upregulating Bcl-2. Moreover, propofol decreased the area of myocardial infarction in rats with MIRI. The GSK3β-Nrf2/HO-1 signaling pathway was activated by propofol. Rescue experiments showed that Nrf2 knockdown alleviated the effects of propofol on oxidative stress and apoptosis in H9c2 cells. In conclusion, propofol attenuated H2O2-induced myocardial cell injury by regulating the GSK3β/Nrf2/HO-1 signaling pathway and alleviating MIRI, suggesting that propofol is a promising therapeutic option for ischemic heart disease.

Nanogold Particles Suppresses 5-Flurouracil-Induced Renal Injury: An Insight into the Modulation of Nrf-2 and Its Downstream Targets, HO-1 and γ-GCS

The development of the field of nanotechnology has revolutionized various aspects in the fields of modern sciences. Nano-medicine is one of the primary fields for the application of nanotechnology techniques. The current study sheds light on the reno-protective impacts of gold nano-particles; nanogold (AuNPs) against 5-flurouracil (5-FU)-induced renal toxicity. Indeed, the use of 5-FU has been associated with kidney injury which greatly curbs its therapeutic application. In the current study, 5-FU injection was associated with a significant escalation in the indices of renal injury, i.e., creatinine and urea. Alongside this, histopathological and ultra-histopathological changes confirmed the onset of renal injury. Both gene and/or protein expression of nuclear factor erythroid 2-related factor 2 (Nrf-2) and downstream antioxidant enzymes revealed consistent paralleled anomalies. AuNPs administration induced a significant renal protection on functional, biochemical, and structural levels. Renal expression of the major sensor of the cellular oxidative status Nrf-2 escalated with a paralleled reduction in the renal expression of the other contributor to this axis, known as Kelch-like ECH-associated protein 1 (Keap-1). On the level of the effector downstream targets, heme oxygenase 1 (HO-1) and gamma-glutamylcysteine synthetase (γ-GCS) AuNPs significantly restored their gene and protein expression. Additionally, combination of AuNPs with 5-FU showed better cytotoxic effect on MCF-7 cells compared to monotreatments. Thus, it can be inferred that AuNPs conferred reno-protective impact against 5-FU with an evident modulatory impact on Nrf-2/Keap-1 and its downstream effectors, HO-1 and γ-GCS, suggesting its potential use in 5-FU regimens to improve its therapeutic outcomes and minimize its underlying nephrotoxicity.

The upregulation of Nur77 decreases ketamine-induced hippocampal neurons toxicity in rats

Ketamine is clinically used as a narcotic. However, ketamine has certain deficits and produces toxicity to neurons. As a member of the NR4A receptor subfamily, Nur77 decreases neurodegenerative disorders. The study aims to investigate the effects of upregulated Nur77 on ketamine-induced rat hippocampal neurons damage and the active mechanism. Neurons were obtained from rat hippocampal and identified by immunofluorescence assays. The treatment groups contained ketamine group, Nur77 group, ketamine + Nur77 group and ketamine + L-cam group. Neurons apoptosis and reactive oxygen species (ROS) were determined by a related kit using flow cytometry. Enzyme NAD(P)H quinone oxidoreductase 1 (NQO1), enzyme heme oxygenase 1 (HO1), Nur77, the expression of Bax, Bcl-2 and cleaved-caspase-3 and inflammatory cytokines were measured using western blot assays and reverse transcription-quantitative PCR (RT-qPCR) assays. Ketamine-induced neurons apoptosis; however, Nur77 decreased ketamine-induced neurons apoptosis. A low level of ROS was observed in two combination groups. Neurons treated by ketamine only had the lowest levels of Nur77, NQO1 and HO1, compared with other treatment groups. The levels of Bax and cleaved-caspase-3 in two combination groups were lower than those in the ketamine group. Furthermore, the ketamine group had higher levels of tumor necrosis factor alpha, IL-1β and IL-6 but the lowest level of IL-4. Upregulated Nur77 reduced the ketamine-induced toxicity in neurons. The mechanism of Nur77 involved antioxidation, apoptosis signaling pathway and inflammation signaling pathway. Our study provides a novel therapy that could attenuate ketamine-induced toxicity.

Modeling the native ensemble of PhuS using enhanced sampling MD and HDX-ensemble reweighting

The cytoplasmic heme binding protein from Pseudomonas aeruginosa, PhuS, plays two essential roles in regulating heme uptake and iron homeostasis. First, PhuS shuttles exogenous heme to heme oxygenase (HemO) for degradation and iron release. Second, PhuS binds DNA and modulates the transcription of the prrF/H small RNAs (sRNAs) involved in the iron-sparing response. Heme binding to PhuS regulates this dual function, as the unliganded form binds DNA, whereas the heme-bound form binds HemO. Crystallographic studies revealed nearly identical structures for apo- and holo-PhuS, and yet numerous solution-based measurements indicate that heme binding is accompanied by large conformational rearrangements. In particular, hydrogen-deuterium exchange mass spectrometry (HDX-MS) of apo- versus holo-PhuS revealed large differences in deuterium uptake, notably in α-helices 6, 7, and 8 (α6,7,8), which contribute to the heme binding pocket. These helices were mostly labile in apo-PhuS but largely protected in holo-PhuS. In contrast, in silico-predicted deuterium uptake levels of α6,7,8 from molecular dynamics (MD) simulations of the apo- and holo-PhuS structures are highly similar, consistent only with the holo-PhuS HDX-MS data. To rationalize this discrepancy between crystal structures, simulations, and observed HDX-MS, we exploit a recently developed computational approach (HDXer) that fits the relative weights of conformational populations within an ensemble of structures to conform to a target set of HDX-MS data. Here, a combination of enhanced sampling MD, HDXer, and dimensionality reduction analysis reveals an apo-PhuS conformational landscape in which α6, 7, and 8 are significantly rearranged compared to the crystal structure, including a loss of secondary structure in α6 and the displacement of α7 toward the HemO binding interface. Circular dichroism analysis confirms the loss of secondary structure, and the extracted ensembles of apo-PhuS and of heme-transfer-impaired H212R mutant, are consistent with known heme binding and transfer properties. The proposed conformational landscape provides structural insights into the modulation by heme of the dual function of PhuS.

Galangin ameliorates severe acute pancreatitis in mice by activating the nuclear factor E2-related factor 2/heme oxygenase 1 pathway

Acute pancreatitis (AP) is a common serious acute condition of the digestive system that remains a clinical challenge. Severe acute pancreatitis (SAP) in particular is characterized by high morbidity and mortality. The present study was designed to investigate the protective effect of Galangin (Gal), a natural flavonol obtained from lesser galangal, on L-arginine-induced SAP in mice and in AR42J cells. Amylase and lipase activities were measured and the histopathology of the pancreas, lung, and kidney was evaluated. Inflammation and oxidative stress were assessed using ELISA, western blotting, RT-PCR, and immunohistochemistry. Gal was shown to reduce proinflammatory cytokine production and reactive oxygen species (ROS) generation in vivo and in vitro. L-arginine treatment reduced the expression of components of the nuclear factor E2-related factor 2 (Nrf2) signaling pathway and the downstream protein heme oxygenase-1 (HO-1) in mice, whereas Gal increased their expression. Furthermore, the Nrf2/HO-1 pathway inhibitor brusatol prevented the anti-inflammatory and antioxidant effects of Gal in mice with SAP. Taken together, our results imply that Gal has protective effects in L-arginine-induced SAP that are induced by the upregulation of the Nrf2/HO-1 pathway, which has anti-inflammatory and antioxidant effects. Thus, Gal may represent a promising treatment for SAP.

Quercetin Exhibits α7nAChR/Nrf2/HO-1-Mediated Neuroprotection Against STZ-Induced Mitochondrial Toxicity and Cognitive Impairments in Experimental Rodents

The objective of the present study was to investigate the α7nAChR-mediated Nrf2-dependant protective activity against streptozotocin (STZ)-induced brain mitochondrial toxicity in Alzheimer's disease (AD)-like rats. STZ (3 mg/kg) was injected through an intracerebroventricular route to induce AD-like dementia. Repeated Quercetin (50 mg/kg, i.p.) administration attenuated cognitive impairments in the STZ-challenged animals during Morris water-maze and Y-maze tests. Quercetin significantly mitigated the STZ-induced increase in cholinergic dysfunction, such as the increase in acetylcholinesterase activity, decrease in acetylcholine level, and activity of choline acetyltransferase, and increase in amyloid-beta aggregation and mitochondrial toxicity in respect of mitochondrial bioenergetics, integrity, and oxidative stress in memory-challenged rat hippocampus, prefrontal cortex and, amygdala. Further, Quercetin significantly attenuated STZ-induced reduction in the α7nAChRs and HO-1 expression levels in the selected rat brain regions. On the contrary, trigonelline (10 mg/kg, i.p.) and methyllycaconitine (2 mg/kg; i.p.) abolished the neuroprotective effects of Quercetin against STZ-induced behavioral, molecular, and biochemical alterations in the AD-like animals. Hence, Quercetin exhibits α7nAChR/Nrf2/HO-1-mediated neuroprotection against STZ-challenged AD-like animals. Thus, Quercetin could be considered as a potential therapeutic option in the management of AD.

S-ketamine alleviates carbon tetrachloride-induced hepatic injury and oxidative stress by targeting the Nrf2/HO-1 signaling pathway

The aim of the present study was to investigate the protective effect of S-ketamine (S-KET) against carbon tetrachloride (CCl4) - induced liver damage and oxidative stress, as well as to elucidate the related underlying mechanisms. Blood was collected to measure biochemical parameters (alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin (TB) and γ-glutamyltransferase (γ-GT)) and the liver was harvested for histopathological analysis of enzymes related to the antioxidant response (malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSH-PX)). Liver cell apoptosis was evaluated using the TUNEL assay. In addition, the expression levels of apoptosis-related proteins and the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway were detected by Western blot analysis to explore potential mechanisms. S-KET protected the liver from CCl4-induced damage. The changes to the liver biochemical parameters (increased ALT, AST, ALP, TB, and γ-GT) and oxidative stress-related indicators (increased MDA; depleted SOD, GSH, and GSH-PX) induced by CCl4 were inhibited by S-KET. S-Ket also inhibited CCl4-induced cell apoptosis, the changes in expression of related proteins, and blocked CCl4-induced liver injury and oxidative stress via activation of the Nrf2/HO-1 signaling pathway. S-KET effectively protected the liver by inhibition of CCl4-induced damage via upregulation the Nrf2/HO-1 signaling pathway.

Dose-Dependent Cardioprotective Effect of Hemin in Doxorubicin-Induced Cardiotoxicity Via Nrf-2/HO-1 and TLR-5/NF-κB/TNF-α Signaling Pathways

Doxorubicin (DOX) is one of the most widely used chemotherapeutic drugs, but its cardiotoxicity has been shown to be a dose-restricting factor during therapy. Finding new agents for reducing these complications is still in critical need. The current study aimed to evaluate the possible cardioprotective effect of hemin (HEM) in DOX-induced cardiotoxicity and exploring the role of toll like receptor-5/nuclear factor kappa-B/tumor necrosis factor-alpha (TLR-5/NF-κB/TNF-α) and nuclear factor erythroid 2-related factor-2/hemeoxygenase-1 (Nrf-2/HO-1) signaling pathways in mediating such effect. Wistar albino rats were randomly divided into five groups. They were administered DOX by interaperitoneal (i.p.) injection (15 mg/kg) on the 5th day of the experiment with or without HEM in different doses (2.5, 5, 10 mg/kg/day) i.p. for 7 days. Results showed that the DOX group had cardiotoxicity as manifested by a significant increase in cardiac enzymes, malondialdehyde (MDA), TLR-5, NF-κB, TNF-α, and cleaved caspase-3 levels with toxic histopathological changes. Based on these findings, HEM succeeded in reducing DOX-induced cardiotoxicity in a dose-dependent effect by stimulation of Nrf-2/HO-1 and inhibition of TLR-5/NF-κB/TNF-α pathways with subsequent antioxidant, anti-inflammatory, and anti-apoptotic effects.

Telmisartan Attenuates Kanamycin-Induced Ototoxicity in Rats

Telmisartan (TM) has been proposed to relieve inflammatory responses by modulating peroxisome proliferator activator receptor-γ (PPARγ) signaling. This study aimed to investigate the protective effects of TM on kanamycin(KM)-induced ototoxicity in rats. Forty-eight, 8-week-old female Sprague Dawley rats were divided into four groups: (1) control group, (2) TM group, (3) KM group, and (4) TM + KM group. Auditory brainstem response was measured. The histology of the cochlea was examined. The protein expression levels of angiotensin-converting enzyme 2 (ACE2), HO1, and PPARγ were measured by Western blotting. The auditory threshold shifts at 4, 8, 16, and 32 kHz were lower in the TM + KM group than in the KM group (all p < 0.05). The loss of cochlear outer hair cells and spiral ganglial cells was lower in the TM + KM group than in the KM group. The protein expression levels of ACE2, PPARγ, and HO1 were higher in the KM group than in the control group (all p < 0.05). The TM + KM group showed lower expression levels of PPARγ and HO1 than the KM group.TM protected the cochlea from KM-induced injuries in rats. TM preserved hearing levels and attenuated the increase in PPARγ and HO1 expression levels in KM-exposed rat cochleae.