Enhanced Heme Oxygenase-1 Expression Research Articles

Emodin alleviates intestinal ischemia/reperfusion-induced lung injury by upregulating HO-1 expression via PI3K/AkT pathway

BackgroundEmodin, a natural anthraquinone derivative found in various Chinese medicinal herbs, has been proved to be an effective therapeutic agent in the treatment of many diseases. However, its effect on lung injury after intestinal ischemia/reperfusion injury remains unknown. This research was designed to investigate whether emodin protects against intestinal ischemia/reperfusion-induced lung injury and to elucidate the underlying molecular mechanisms in vivo and in vitro. MethodsIntestinal ischemia/reperfusion injury was induced by occluding the superior mesenteric artery in mice, and mouse lung epithelial-12 cells were subjected to oxygen-glucose deprivation and reoxygenation to establish an in vitro model. ResultsOur data indicated that emodin treatment reduced intestinal ischemia/reperfusion-induced oxidative stress, inflammation and apoptosis in lung tissues and alleviated lung injury. However, the protective effects of emodin on intestinal ischemia/reperfusion-induced lung injury were reversed by the protein kinase B inhibitor triciribine or the heme oxygenase-1 inhibitor tin protoporphyrin IX. The protein kinase inhibitor triciribine also downregulated the expression of heme oxygenase-1. ConclusionIn conclusion, our data suggest that emodin treatment protects against intestinal ischemia/reperfusion-induced lung injury by enhancing heme oxygenase-1 expression via activation of the PI3K/protein kinase pathway. Emodin may act as a potential therapeutic agent for the prevention and treatment of lung injury induced by intestinal ischemia/reperfusion.

Cytoprotective Role of Heme Oxygenase-1 in Cancer Chemoresistance: Focus on Antioxidant, Antiapoptotic, and Pro-Autophagy Properties.

Chemoresistance remains the foremost challenge in cancer therapy. Targeting reactive oxygen species (ROS) manipulation is a promising strategy in cancer treatment since tumor cells present high levels of intracellular ROS, which makes them more vulnerable to further ROS elevation than normal cells. Nevertheless, dynamic redox evolution and adaptation of tumor cells are capable of counteracting therapy-induced oxidative stress, which leads to chemoresistance. Hence, exploring the cytoprotective mechanisms of tumor cells is urgently needed to overcome chemoresistance. Heme oxygenase-1 (HO-1), a rate-limiting enzyme of heme degradation, acts as a crucial antioxidant defense and cytoprotective molecule in response to cellular stress. Recently, emerging evidence indicated that ROS detoxification and oxidative stress tolerance owing to the antioxidant function of HO-1 contribute to chemoresistance in various cancers. Enhanced HO-1 expression or enzymatic activity was revealed to promote apoptosis resistance and activate protective autophagy, which also involved in the development of chemoresistance. Moreover, inhibition of HO-1 in multiple cancers was identified to reversing chemoresistance or improving chemosensitivity. Here, we summarize the most recent advances regarding the antioxidant, antiapoptotic, and pro-autophagy properties of HO-1 in mediating chemoresistance, highlighting HO-1 as a novel target for overcoming chemoresistance and improving the prognosis of cancer patients.

5-Aminolevulinic acid combined with ferrous iron ameliorates scrotal heat stress-induced spermatogenic damage by enhancing HO-1 expression

To explore whether 5-Aminolevulinic acid combined with ferrous iron(5-ALA/Fe2+) could protect testicular tissues damage of mice subjected to heat stress (HS) and provide its underlying mechanisms. 5-ALA/Fe2+ was administered intragastrically to mice for 10days, then exposed to a scrotal heat stress at 43°C for 20min on third day. Testes were harvested for morphologic and histopathological examination, oxidative stress, apoptosis, heme oxygenase-1 (HO-1) and inflammation detection. The mitogen-activated protein kinases (MAPK) signaling pathway in testis and CD4+FoxP3+regulatory T (Treg) cells in spleen were also investigated. Compared to control group, the testis weight decreased and histological damage severed in HS group. Besides, HS also increased the oxidative stress, apoptosis and inflammation in testis. However, these indicators were ameliorated after 5-ALA/Fe2+ treatment but deteriorated after receiving ZnPPIX. The expression of HO-1 was increased both in HS group and 5-ALA/Fe2+ group. The protein expression levels of MAPK proteins were activated by HS and inhibited by 5-ALA/Fe2+. The CD4+FoxP3+ Treg generation was reduced by HS and increased by 5-ALA/Fe2+. In this study, we have demonstrated that 5-ALA/Fe2+ ameliorated the spermatogenic damage induced by scrotal heat stress via up-regulating the expression of HO-1 and inhibiting MAPK mediated oxidative stress and apoptosis and inducing CD4+Foxp3+ Tregs to inhibit the inflammation induced by HS in mice.

Anti-inflammatory activity of 2-methoxy-4-vinylphenol involves inhibition of lipopolysaccharide-induced inducible nitric oxidase synthase by heme oxygenase-1

Background 2-Methoxy-4-vinylphenol (2M4VP) is a natural anti-inflammatory compound derived from red wine, but its underlying mechanism remains unclear. Heme oxygenase-1 (HO-1), an anti-inflammatory enzyme, inhibits NO gene expression, while nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor involved in HO-1 production, binds to the antioxidant response element (ARE) in the nucleus and promotes HO-1 transcription. Based on the hypothesis that the inhibitory effect of 2M4VP on NO production is mediated by HO-1, we examined the possible mechanism of the anti-inflammatory activity of 2M4VP in this study. Materials and methods The anti-inflammatory activity of 2M4VP was analyzed by Griess method, ELISA, qPCR, and Western blotting using LPS-treated macrophage lineage RAW264.7 cells. The impact of 2M4VP on the Nrf2/ARE pathway was also analyzed using immunocytochemistry and an ARE luciferase reporter using HEK293 cells. Results The results showed that 2M4VP reduced the production of LPS-induced NO and inducible nitric oxidase synthase (iNOS). In addition, 2M4VP increased the expression of HO-1, while pretreatment with the Nrf2 inhibitor ML385 downregulated HO-1 expression. 2M4VP induced Kelch-like ECH-associated protein 1 (Keap1) degradation. Furthermore, it promoted Nrf2 nuclear translocation and increased luciferase activity by binding to the ARE. Conclusions 2M4VP induces Keap1 degradation and promotes Nrf2 nuclear translocation. Activation of Nrf2/ARE pathway enhances HO-1 expression and leads to iNOS inhibition for anti-inflammatory function.

Different Acute Kidney Injury Patterns after Renal Ischemia Reperfusion Injury and Extracorporeal Membrane Oxygenation in Mice.

The use of extracorporeal membrane oxygenation (ECMO) is associated with acute kidney injury (AKI) in thoracic organ transplantation. However, multiple other factors contribute to AKI development after these procedures such as renal ischemia-reperfusion injury (IRI) due to hypo-perfusion of the kidney during surgery. In this study, we aimed to explore the kidney injury patterns in mouse models of ECMO and renal IRI. Kidneys of C57BL/6 mice were examined after moderate (35 min) and severe (45 min) unilateral transient renal pedicle clamping and 2 h of veno-venous ECMO. Renal injury markers, neutrophil infiltration, tubular transport function, pro-inflammatory cytokines, and renal heme oxygenase-1 (HO-1) expression were determined by immunofluorescence and qPCR. Both procedures caused AKI, but with different injury patterns. Severe neutrophil infiltration of the kidney was evident after renal IRI, but not following ECMO. Tubular transport function was severely impaired after renal IRI, but preserved in the ECMO group. Both procedures caused upregulation of pro-inflammatory cytokines in the renal tissue, but with different time kinetics. After ECMO, but not IRI, HO-1 was strongly induced in tubular cells indicating contact with hemolysis-derived proteins. After IRI, HO-1 was expressed on infiltrating myeloid cells in the tubulo-interstitial space. In conclusion, renal IRI and ECMO both caused AKI, but kidney damage after renal IRI was more pronounced including severe neutrophil infiltration and tubular transport impairment. Enhanced HO-1 expression in tubular cells after ECMO encourages limitation of hemolysis as a therapeutic approach to reduce ECMO-associated AKI.

The deubiquitinase USP7 regulates oxidative stress through stabilization of HO-1.

Heme oxygenase-1 (HO-1) is an inducible heme degradation enzyme that plays a cytoprotective role against various oxidative and inflammatory stresses. However, it has also been shown to exert an important role in cancer progression through a variety of mechanisms. Although transcription factors such as Nrf2 are involved in HO-1 regulation, the posttranslational modifications of HO-1 after oxidative insults and the underlying mechanisms remain unexplored. Here, we screened and identified that the deubiquitinase USP7 plays a key role in the control of redox homeostasis through promoting HO-1 deubiquitination and stabilization in hepatocytes. We used low-dose arsenic as a stress model which does not affect the transcriptional level of HO-1, and found that the interaction between USP7 and HO-1 is increased after arsenic exposure, leading to enhanced HO-1 expression and attenuated oxidative damages. Furthermore, HO-1 protein is ubiquitinated at K243 and subjected to degradation under resting conditions; whereas when after arsenic exposure, USP7 itself can be ubiquitinated at K476, thereafter promoting the binding between USP7 and HO-1, finally leading to enhanced HO-1 deubiquitination and protein accumulation. Moreover, depletion of USP7 and HO-1 inhibit liver tumor growth in vivo, and USP7 positively correlates with HO-1 protein level in clinical human hepatocellular carcinoma (HCC) specimens. In summary, our findings reveal a critical role of USP7 as a HO-1 deubiquitinating enzyme in the regulation of oxidative stresses, and suggest that USP7 inhibitor might be a potential therapeutic agent for treating HO-1 overexpressed liver cancers.

Heme oxygenase‐1 induction by gallic acid‐ g ‐chitosan is an important event in modulating adipocyte differentiation

Obesity, one of the common worldwide chronic health diseases co-relates with adipogenesis. Adipogenesis is a complex biological action of the emergence of mature adipocytes from the differentiation of pre-adipocytes and the disfunction of this process leads to the development of metabolic issues in obesity. Recently, much attention has been paid to utilizing natural compounds to discover their biological activities. This study focused on investigating the probable anti-adipogenic effects of gallic acid-g-chitosan (GAC) and plain chitosan (PC) through regulating the heme oxygenase-1 (HO-1)/Nrf2 pathway on mesenchymal stem cells. Gallic acid is grafted onto the PC backbone to improve its specific physical and biological properties. GAC showed promising anti-adipogenic effects by enhancing HO-1 expression and lipolysis and as well as suppressing lipid accumulation, reactive oxygen species, and pro-inflammatory cytokines production, transcription factor expression compared to the PC treatment. On the contrary, zinc protoporphyrin ІX (ZnPP), a HO-1 inhibitor reversed these effects of GAC on adipogenesis. Taken all together, this study revealed that grafting GA onto the chitosan improved potential anti-adipogenic activity by induction of the HO-1/Nrf2 pathway on mesenchymal stem cells (MSCs). PRACTICAL APPLICATIONS: GAC is a well-known copolymer with versatile bioactivities such as antimicrobial, antioxidant, and anti-diabetic activity. However, the anti-adipogenic effect of GAC has not been explored in MSCs. This study demonstrated that GAC inhibited adipocyte differentiation in MSCs through HO-1 activation. These findings suggest that GAC can be applied practically from different perspectives. GAC can be applied in the pharmacological industry to the development of anti-obesity drugs, medicinal perspectives for the treatment of obesity and obesity-related diseases, and in the food industry as a functional food to promote health and decrease the risk of diseases.

Activation of α7nAChR preserves intestinal barrier integrity by enhancing the HO-1 / STAT3 signaling to inhibit NF-κB activation in mice

BackgroundActivation of alpha-7 nicotinic acetylcholine receptor (α7nAChR) can inhibit a systemic inflammatory response and preserve intestinal barrier integrity. This study aimed at elucidating the molecular mechanisms by which α7nAChR activation could inhibit intestinal barrier injury and cholestatic liver fibrosis in mice following bile duct ligation (BDL). Materials and methodsThe intestine-specific heme oxygenase-1 (HO-1) knockout VillinCreHmox1-/- and control Hmox1flox/flox C57BL/6 mice were subjected to the BDL procedure. The therapeutic effects of GST-21, a specific ligand for α7nAChR, on systemic and intestinal inflammation, intestinal barrier integrity, liver fibrosis and injury, HO-1 expression, STAT3, AKT and NF-κBp65 activation were examined in these mice and intestinal epithelial cells after being co-cultured with macrophages. ResultsCompared with the vehicle-injected BDL group, treatment with GST-21 to activate α7nAChR decreased intestinal and liver injury and fibrosis in BDL mice, accompanied by reducing serum cytokine levels. In addition, activation of α7nAChR preserved the levels of tight junction protein expression and intestinal epithelial barrier integrity in BDL mice and epithelial cells following co-cultured with macrophages. The therapeutic effects of α7nAChR activation were mediated by enhancing HO-1 expression and STAT3 phosphorylation, and reducing the NF-κBp65 activation in intestinal tissues and epithelial cells co-cultured with macrophages. Finally, activation of α7nAChR induced HO-1 expression and STAT3 phosphorylation in an interdependent manner, independent of the PI3K/AKT signaling. ConclusionActivation of α7nAChR enhanced HO-1 expression and STAT3 signaling to inhibit NF-κB activation, preserving the intestinal barrier integrity, and reducing inflammation and liver fibrosis in cholestatic mice. Therefore, targeting α7nAChR may be a promising interventional strategy for primary biliary cholangitis.

Eicosapentaenoic Acid Increases Vascular and Pulmonary Endothelial Ferritin Levels with Enhanced Heme Oxygenase-1 Expression during Inflammation

Lead Author's Financial Disclosures Nothing to disclose. Study Funding Amarin Pharma Inc. and Elucida Research LLC. Background/Synopsis Inducible heme oxygenase-1 (HO-1) catalyzes the degradation of heme into biliverdin, carbon monoxide, and ferrous iron. Increased free iron triggers production of intracellular ferritin. Ferritin as well as the other HO-1 products have potent antioxidant, vasodilatory and anti-inflammatory actions. Unlike trials using mixed omega-3 formulations, eicospentaenoic acid (EPA) only treatment (icosapent ethyl) was associated with reduced cardiovascular (CV) events in high-risk patients with elevated triglycerides (REDUCE-IT) but the mechanism is not fully understood. Objective/Purpose This study compared the treatment effects of EPA on protein expression in endothelial cells (ECs) isolated from vein and pulmonary tissue under conditions of inflammation using the cytokine IL-6. Methods Human umbilical vein endothelial cells (HUVECs) and pulmonary microvascular ECs were first challenged with IL-6 (12 ng/mL) for 2 hours, and then treated with EPA (40 micromolar) for 24 hours. Proteomic analysis was performed using LC/MS to measure relative expression levels of >1,000 proteins simultaneously. Only significant (p<0.05) changes in expression between treatment groups >1-fold were included in the analysis. Results Cells treated with EPA significantly down/up-regulated expression of 310/276 and 212/229 proteins in vascular and pulmonary ECs, respectively, compared with IL-6 alone. In particular, EPA increased levels of HO-1 by 220% (p = 7.9E-50) and 190% (p = 2.8E-32) in vascular and pulmonary ECs, respectively. Increased HO-1 expression resulted in increased levels of ferritin light chain by 120% (p = 4.0E10-5) and 110% (p = 0.049) in vascular and pulmonary ECs, respectively, and ferritin heavy chain by 110% (p = 0.0002) and 160% (p = 1.4E10-6), respectively. Conclusions EPA increased expression of HO-1, a protein that has broad atheroprotective benefits, in both vascular and pulmonary ECs that correlated with increased ferritin levels during inflammation. The ability of EPA to enhance cytoprotective proteins has therapeutic implications for patients at risk for CV disease. Nothing to disclose.

Trichosanthis Semen Suppresses Lipopolysaccharide-Induced Neuroinflammation by Regulating the NF-κB Signaling Pathway and HO-1 Expression in Microglia.

Neuroinflammation, which is mediated by microglia that release various inflammatory cytokines, is a typical feature of neurodegenerative diseases (NDDs), such as Alzheimer’s disease and Parkinson’s disease. Hence, alleviating neuroinflammation by downregulating pro-inflammatory action, and upregulating anti-inflammatory action of microglia is an efficient therapeutic target for NDDs. In this study, we evaluated whether trichosanthis semen (TS), a dried ripe seed of Trichosanthes kirilowii Maximowicz, reduces lipopolysaccharide (LPS)-induced neuroinflammation by regulating microglial responses in vitro and in vivo. Our results presented that TS reduced the release of pro-inflammatory mediators, such as nitric oxide (NO), inducible NO synthase, tumor necrosis factor-α, interleukin-1β, and interleukin-6 via inhibition of the nuclear factor kappa B (NF-κB) signaling pathway in LPS-treated BV2 microglial cells. Moreover, TS induced anti-inflammatory mediators, such as interleukin-10, found in inflammatory zone 1, and chitinase 3-like 3 by the upregulation of heme oxygenase 1 (HO-1). We further confirmed that TS administration suppressed microglial activation, but enhanced HO-1 expression in LPS-injected mice. These results suggest that TS has anti-neuroinflammatory effects via inhibition of NF-κB signaling through the activation of HO-1, and that TS may be a therapeutical candidate for NDDs treatment.

3,5-Dicaffeoylquinic Acid Lowers 3T3-L1 Mitotic Clonal Expansion and Adipocyte Differentiation by Enhancing Heme Oxygenase-1 Expression.

Adipogenesis is a complex process in which cell commitment and mitotic clonal expansion (MCE) are in-sequence crucial events leading to terminal adipocyte differentiation. The molecules able to block some key signals in this cascade can hamper adipogenesis becoming promising agents to counteract hyperplasia and hypertrophy of adipose tissue. Mono- and di-caffeoylquinic acid isomers are biologically active polyphenols, displaying in vitro and in vivo antioxidant, hepatoprotective, anti-diabetic and anti-obesity properties. Among these isomers, 3,5-dicaffeoylquinic acid (DCQA) has been reported to inhibit lipid accumulation in adipose cells more successfully than others. Thus, we investigated DCQA effects and molecular mechanisms on 3T3-L1 pre-adipocytes induced to differentiate with a hormonal cocktail (MDI). Oil Red O incorporation assessed that DCQA pre-treatment inhibited lipid accumulation in 3T3-L1 cells induced to differentiate for 10 days. At this time, an increased phosphorylation of both AMP-activated kinase and acetyl-CoA carboxylase, as well as a strong decrease in fatty acid synthase protein level, were registered by immunoblotting, thereby suggesting that DCQA treatment can reduce fatty acid anabolism in 3T3-L1 adipocytes. Furthermore, BrdU incorporation assay, performed 48 h after hormonal stimulation, revealed that DCQA treatment was also able to hinder the 3T3-L1 cell proliferation during the MCE, which is an essential step in the adipogenic process. Thus, we focused our attention on early signals triggered by the differentiation stimuli. In the first hours after hormonal cocktail administration, the activation of ERK1/2 and Akt kinases, or CREB and STAT3 transcription factors, was not affected by DCQA pre-treatment. Whereas 24 h after MDI induction, DCQA pre-treated cells showed increased level of the transcription factor Nrf2, that induced the expression of the antioxidant enzyme heme oxygenase 1 (HO-1). In control samples, the expression level of HO-1 was reduced 24 h after MDI induction in comparison with the higher amount of HO-1 protein found at 2 h. The HO-1 decrease was functional by allowing reactive oxygen species to boost and allowing cell proliferation induction at the beginning of MCE phase. Instead, in DCQA-treated cells the HO-1 expression was maintained at high levels for a further 24 h; in fact, its expression decreased only 48 h after MDI stimulation. The longer period in which HO-1 expression remained high led to a delay of the MCE phase, with a subsequent inhibition of both C/EBP-α expression and adipocyte terminal differentiation. In conclusion, DCQA counteracting an excessive adipose tissue expansion may become an attractive option in obesity treatment.

Cytoprotective effects of fermented oyster extracts against oxidative stress-induced DNA damage and apoptosis through activation of the Nrf2/HO-1 signaling pathway in MC3T3-E1 osteoblasts.

Osteoblast damage by oxidative stress has been recognized as a cause of bone-related disease, including osteoporosis. Recently, we reported that fermented Pacific oyster (Crassostrea gigas) extracts (FO) inhibited osteoclastogenesis and osteoporosis, while promoting osteogenesis. However, since the beneficial potential of FO on osteoblasts is not well known, in the present study, we investigated the cytoprotective effect of FO against oxidative stress in MC3T3-E1 osteoblasts. Our results demonstrated that FO inhibited hydrogen peroxide (H2O2)-induced DNA damage and cytotoxicity through the rescue of mitochondrial function by blocking abnormal ROS accumulation. FO also prevented apoptosis by suppressing loss of mitochondrial membrane potential and cytosolic release of cytochrome c, decreasing the rate of Bax/Bcl-2 expression and reducing the activity of caspase-9 and caspase-3 in H2O2-stimulated MC3T3-E1 osteoblasts, suggesting that FO protected MC3T3-E1 osteoblasts from the induction of caspase dependent- and mitochondria-mediated apoptosis by oxidative stress. In addition, FO markedly promoted the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2), which was associated with the enhanced expression of heme oxygenase-1 (HO-1). However, inhibiting the expression of HO-1 by artificially blocking the expression of Nrf2 using siRNA significantly eliminated the protective effect of FO, indicating that FO activates the Nrf2/HO-1 signaling pathway in MC3T3-E1 osteoblasts to protect against oxidative stress. Based on the present data, FO is thought to be useful as a potential therapeutic agent for the inhibition of oxidative stress in osteoblasts.

Roles of JNK/Nrf2 Pathway on Hemin-Induced Heme Oxygenase-1 Activation in MCF-7 Human Breast Cancer Cells.

Heme oxygenase-1 (HO-1) is highly induced in various human disease states, including cancer, indicating that HO-1 is an emerging target of cancer therapy. In this study, we investigated that the mechanisms of hemin-induced HO-1 expression and its signaling pathways in human breast cancer cell. We used MCF-7 cells, a human breast cancer cell line. Hemin increased HO-1 expression in MCF-7 cells in a dose- and time-dependent manner. Hemin enhanced HO-1 expression through the activation of c-Jun N-terminal kinases (JNK) signaling pathway. Hemin also induced activation of Nrf2, a major transcription factor of HO-1 expression. These responses in MCF-7 cells were completely blocked by pretreatment with brazilin, a HO-1 regulator. These results indicated that brazilin inhibits hemin-induced HO-1 expressions through inactivation of JNK/Nrf2 in MCF-7 cells. Thus, our findings suggest that HO-1 is an important anticancer-target of brazilin in human breast cancer.

P38 MAPK and Nrf2 Activation Mediated Naked Gold Nanoparticle Induced Heme Oxygenase-1 Expression in Rat Aortic Vascular Smooth Muscle Cells

Heme oxygenase 1 (HO-1) is mainly regulated by the redox-sensitive transcription factor, namely nuclear factor erythroid 2-related factor 2 (Nrf2). We previously found a physically-made gold nanoparticle (GNP) can affect migration, adhesion, and proliferation of rat aortic vascular smooth muscle cells (VSMCs). This study was sought to investigate whether the GNP can affect HO-1 expression level in VSMCs. Cellular fractionation, Western blotting, and immunofluorescence microscopy were used to determine Nrf2 translocation and phosphorylation. SiRNA interference was used to examine role of Nrf2 in GNP-induced HO-1 expression. The GNP concentration- and time-dependently enhanced HO-1 protein and mRNA expression; however, the mRNA induction was declined after 16h treatment. The GNP treatment caused Nrf2 expression level and phosphorylation. In addition, it induced cytosolic Nrf2 translocation into nucleus. The HO-1 induction was inhibited by a ROS scavenger N-acetylcysteine (NAC), thiol-containing antioxidants (glutathione [GSH] and dithiothreitol [DTT]), JNK and p38 MAPK inhibitors, and nuclear transport inhibitor leptomycin. Meanwhile, the GNP-induced Nrf2 translocation (activation) was also reduced by NAC, JNK and p38 MAPK inhibitors, and nuclear transport inhibitor. Intriguingly, the GNP only enhanced activation of p38 MAPK but not JNK1/2. Finally, introduction of Nrf2 siRNA to cells to knockdown Nrf2 expression significantly inhibited GNP-induced HO-1 protein expression. This study elucidates the action mechanism that the naked physically-made GNP can enhance HO-1 expression in rat aortic VSMCs by inducing Nrf2 expression and phosphorylation and translocation into nucleus. The Nrf2 activation is mediated through a redox-related reaction and p38 MAPK activation.

Heme oxygenase-1 promoter (GT) n polymorphism associates with HIV neurocognitive impairment.

ObjectiveTo determine whether regulatory variations in the heme oxygenase-1 (HO-1) promoter (GT)n dinucleotide repeat length could identify unique population genetic risks for neurocognitive impairment (NCI) in persons living with HIV (PLWH), we genotyped 528 neurocognitively assessed PLWH of European American and African American descent and linked genotypes to cognitive status.MethodsIn this cross-sectional study of PLWH (the CNS HIV Antiretroviral Therapy Effect Research cohort), we determined HO-1 (GT)n repeat lengths in 276 African Americans and 252 European Americans. Using validated criteria for HIV-associated NCI (HIV NCI), we found associations between allele length genotypes and HIV NCI and between genotypes and plasma markers of monocyte activation and inflammation. For comparison of HO-1 (GT)n allele frequencies with another population of African ancestry, we determined HO-1 (GT)n allele lengths in African PLWH from Botswana (n = 428).ResultsPLWH with short HO-1 (GT)n alleles had a lower risk for HIV NCI (OR = 0.63, 95% CI: 0.42–0.94). People of African ancestry had a lower prevalence of short alleles and higher prevalence of long alleles compared with European Americans, and in subgroup analyses, the protective effect of the short allele was observed in African Americans and not in European Americans.ConclusionsOur study identified the short HO-1 (GT)n allele as partially protective against developing HIV NCI. It further suggests that this clinical protective effect is particularly relevant in persons of African ancestry, where the lower prevalence of short HO-1 (GT)n alleles may limit induction of HO-1 expression in response to inflammation and oxidative stress. Therapeutic strategies that enhance HO-1 expression may decrease HIV-associated neuroinflammation and limit HIV NCI.

Activation of the Nrf2/HO-1 Pathway by Amomum villosum Extract Suppresses LPS-Induced Oxidative Stress In Vitro and Ex Vivo.

Despite its deleterious effects on living cells, oxidative stress plays essential roles in normal physiological processes and provides signaling molecules for cell growth, differentiation, and inflammation. Macrophages are equipped with antioxidant mechanisms to cope with intracellular ROS produced during immune response, and Nrf2 (NF-E2-related factor 2)/HO-1 (heme oxygenase-1) pathway is an attractive target due to its protective effect against ROS-induced cell damage in inflamed macrophages. We investigated the effects of ethanol extract of A. villosum (AVEE) on lipopolysaccharide- (LPS-) stimulated inflammatory responses generated via the Nrf2/HO-1 signaling pathway in murine peritoneal macrophages and RAW 264.7 cells. AVEE was found to suppress the NF-κB signaling pathway, thus, to reduce proinflammatory cytokine, nitric oxide, and prostaglandin levels in peritoneal macrophages and Raw 264.7 cells treated with LPS, and to enhance HO-1 expression by activating Nrf2 signaling. Furthermore, these anti-inflammatory effects of AVEE were diminished when cells were pretreated with SnPP (a HO-1 inhibitor). HPLC analysis revealed AVEE contained quercetin, a possible activator of the Nrf2/HO-1 pathway. These results show A. villosum ethanol extract exerts anti-inflammatory effects by activating the Nrf2/HO-1 pathway in LPS-stimulated macrophages.

Propranolol diminished severity of rat EAE by enhancing immunoregulatory/protective properties of spinal cord microglia

Sympathetic dysfunction is suggested to contribute to development of multiple sclerosis and experimental autoimmune encephalomyelitis (EAE) alike. Considering important role of microglia in development/resolution of neuroinflammation, contribution of noradrenaline, the key sympathetic end-point mediator, in modulation of microglial phenotypic and functional properties in rat EAE model was examined. The study showed that noradrenaline acting in neurocrine and autocrine/paracrine way might influence microglia during EAE. Propranolol treatment over the effector phase moderated EAE course. This was associated with the increased proportion of microglia expressing CX3CR1, the key molecule in their immunomodulatory/neuroprotective action, and upregulation of CX3CR1 downstream Nrf2 gene. This correlated with the increased heme oxygenase-1 (HO-1) expression and phagocytic capacity of microglia, and their phenotypic changes mirrored in increased proportion of CD163- and CD83-expressing cells. The enhanced HO-1 expression was linked with the decreased proportion of microglial cells expressing IL-1β and IL-23, and possibly IL-6, followed by increased proportion of IL-10–expressing microglia, and downregulated MCP-1/CCL2 expression. Consistently, spinal cord infiltration with blood-borne myeloid and CD4+ T cells, as well as CD4+ T-cell reactivation/proliferation and differentiation into highly pathogenic IL-17+ cells co-producing IFN-γ and GM-CSF were decreased in propranolol-treated rats compared with saline-injected controls. The in vitro investigations of the effects of noradrenaline on microglia showed that noradrenaline through β-adrenoceptor may influence Nrf2 expression also via CX3CR1-independent route. The study suggests β-adrenoceptor–mediated neuroinflammation-promoting role of noradrenaline in EAE via modulation of microglial Nrf2 expression, and thereby forms the basis for further translational pharmacological research to improve multiple sclerosis therapy.

Naringenin-induced HO-1 ameliorates high glucose or free fatty acids-associated apoptosis via PI3K and JNK/Nrf2 pathways in human umbilical vein endothelial cells

Naringenin (NG), a flavanone extracted from various plants, has potent vasoprotective effects likely related to the induction of heme oxygenase-1 (HO-1). In the current study, we investigated mechanisms underlying the effect of NG on HO-1 expression and high glucose (HG)- or free fatty acids (FFA)-induced apoptosis in human umbilical vein endothelial cells (HUVECs). First, we found that HUVECs exposed to NG exhibited enhanced HO-1 expression in a concentration- and time-dependent manner. Moreover, HUVECs treated with NG exhibited activation of phosphoinositide 3 kinase (PI3K)/Akt, extracellular-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). LY294002 (a PI3K inhibitor) and SP600125 (a JNK inhibitor) reduced NG-induced HO-1 expression, whereas BIRB796 (a p38 inhibitor) and PD98059 (an ERK inhibitor) had no effect. The cytoprotective effects of NG were correlated with activation of the transcription factor NF-E2-related factor 2 (Nrf2), a critical regulator of HO-1 expression. Indeed, the results of our experiments using LY294002 and SP600125 indicated that NG may stimulate Nrf2 through PI3K/Akt and JNK pathway activation. Moreover, treatment of HUVECs with Nrf2 siRNA decreased NG-induced HO-1 expression. Finally, pretreatment of HUVECs with NG remarkably reduced HG- or FFA-induced cell apoptosis, and this effect was greatly abrogated in the presence of SnPP (an HO-1 inhibitor). Above all, our data show that NG increased HO-1 expression and reduced HG- or FFA-induced cell apoptosis in HUVECs by upregulating PI3K, JNK, and Nrf2 pathways, which may confer an adaptive survival response in diabetes-induced vascular injury.

Lunasin attenuates oxidant-induced endothelial injury and inhibits atherosclerotic plaque progression in ApoE-/- mice by up-regulating heme oxygenase-1 via PI3K/Akt/Nrf2/ARE pathway.

Oxidative stress-induced vascular endothelial cell (VEC) injury is a major mechanism in the initiation and development of atherosclerosis. Lunasin, a soybean-derived 43-aa peptide, has been previously shown to possess potent antioxidant and anti-inflammatory activities other than its established anticancer activities. This study investigated the effects of lunasin on protecting VECs from oxidative damage and inhibiting atherosclerotic plaque progression in apolipoprotein E-deficient (ApoE-/-) mice and explored its underlying mechanism. Biochemical and histologic analyses were performed by using EA.hy926 human VECs and a high-fat diet (HFD) ApoE-/- mouse atherosclerosis model. Our data indicated that lunasin attenuated H2O2-induced, mitochondria-dependent endothelial apoptosis via down-regulating Bax and up-regulating Bcl-2, inhibiting the mitochondrial depolarization, and reducing the release of cytochrome c, as well as decreasing the activation of caspase-9 and caspase-3 in vitro and in vivo. Mechanic studies showed that lunasin significantly up-regulated heme oxygenase-1 via the PI3K/Akt/nuclear factor erythroid 2-related factor 2/antioxidant response element pathway, and reduced H2O2-induced ROS production in VECs, thereby attenuating oxidant-induced endothelial injury and inhibiting atherosclerotic plaque progression in ApoE-/- mice. In conclusion, our in vitro and in vivo data suggest that lunasin protects VECs from oxidative damage by enhancing heme oxygenase-1 expression via activation of the PI3K/Akt/nuclear factor erythroid 2-related factor 2/antioxidant response element pathway and inhibiting mitochondria-dependent apoptosis, thereby effectively attenuating atherosclerosis in HFD-fed ApoE-/- mice. Lunasin may act as a potential therapeutic agent for the prevention and treatment of atherosclerosis.-Gu, L., Ye, P., Li, H., Wang, Y., Xu, Y., Tian, Q., Lei, G., Zhao, C., Gao, Z., Zhao, W., Tan, S. Lunasin attenuates oxidant-induced endothelial injury and inhibits atherosclerotic plaque progression in ApoE-/- mice by up-regulating heme oxygenase-1 via PI3K/Akt/Nrf2/ARE pathway.

Inhibition of miR-92a Suppresses Oxidative Stress and Improves Endothelial Function by Upregulating Heme Oxygenase-1 in db/db Mice.

Inhibition of microRNA-92a (miR-92a) is reported to suppress endothelial inflammation and delay atherogenesis. We hypothesize that miR-92a inhibition protects endothelial function through suppressing oxidative stress in diabetic db/db mice. In this study, we found elevated expression of miR-92a in aortic endothelium from db/db mice and in renal arteries from diabetic subjects. Endothelial cells (ECs) exposed to advanced glycation end products (AGEs) and oxidized low-density lipoprotein express higher level of miR-92a. Overexpression of miR-92a impairs endothelium-dependent relaxations (EDRs) in C57BL/6 mouse aortas. Overexpression of miR-92a suppresses expression of heme oxygenase-1 (HO-1), a critical cytoprotective enzyme, whereas inhibition of miR-92a increases HO-1 expression in human umbilical vein ECs (HUVECs) and db/db mouse aortas. Importantly, miR-92a inhibition by Ad-anti-miR-92a improved EDRs and reduced reactive oxygen species (ROS) production in db/db mouse aortas. HO-1 inhibition by SnMP or HO-1 knockdown by shHO-1 reversed the suppressive effect of miR-92a inhibition on ROS production induced by AGE treatment in C57BL/6 mouse aortas. In addition, SnMP reversed miR-92a inhibition-induced improvement of EDRs in AGE-treated C57BL/6 mouse aortas and in db/db mouse aortas. Expression of miR-92a is increased in diabetic aortic endothelium and inhibition of miR-92a exerts vasoprotective effect in diabetic mice through HO-1 upregulation in ECs. MiR-92a expression is elevated in diabetic ECs. MiR-92a overexpression impairs endothelial function and suppresses HO-1 expression in ECs. Inhibition of miR-92a attenuates oxidative stress and improves endothelial function through enhancing HO-1 expression and activity in db/db mouse aortas. Antioxid. Redox Signal. 28, 358-370.