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SARS-CoV-2 virus infection starts with the internalization of the viral particle into the host cells, mainly the upper respiratory system epithelial cells which have the highest expression of the ACE2 receptor which is essential for the internalization process. The pathophysiology of severe forms of COVID-19 disease results not only from direct, cytopathic viral effect but also from immune response dysregulation of the host resulting in hyperinflammatory state and oxidative stress. The nuclear factor erythroid 2-related factor 2 (Nrf2) ability to protect cells and induce a rapid anti-inflammatory and antioxidant response primarily depends on its constitutive cellular expression, which can be affected by numerous endogenous and exogenous factors. The binding of Nrf2 to cellular receptors leads to the transcription of a large number of genes encoding various antioxidant enzymes and other cytoprotective molecules, including heme oxygenase-1(HO-1). Activation of HO-1 results in antioxidant, anti-inflammatory and anti-apoptotic effects. Based on previous studies, the Nrf2/HO-1 pathway provides protection against oxidative stress and inflammatory and immune response which is significant in COVID-19 infection, which is characterized by a strong hyperinflammatory response. This narrative review aims to describe the role of the hyperinflammatory response in the development of COVID-19 infection, with a focus on the NrF2/HO-1 pathway.

Persistent uptake of high‐calorie diets induces the storage of excessive lipid in visceral adipose tissue. Lipids secreted from obese adipose tissue are accumulated in peripheral tissues such as the liver, pancreas, and muscle, and impair insulin sensitivity causing type 2 diabetes mellitus (T2DM). Furthermore, the accumulation of inflammatory cytokines and lipids in the liver induces apoptosis and fibrogenesis, and ultimately causes nonalcoholic steatohepatitis (NASH). To modulate obese tissue environments, it is challenged to selectively deliver inducers of heme oxygenase‐1 (HO‐1) to adipose tissue with the aid of a prohibitin targeting drug delivery system. Prohibitin binding peptide (PBP), an oligopeptide targeting prohibitin rich in adipose tissue, is conjugated on the surface of Hemin‐ or CoPP‐loaded poly(lactide‐co‐glycolide) nanoparticles (PBP‐NPs). PBP‐NPs efficiently differentiate lipid storing white adipocytes into energy‐generating brown adipocytes in T2DM and NASH models. In addition, PBP‐NPs are found to target prohibitin overexpressed fatty liver in the NASH model and inhibit hepatic uptake of circulating lipids. Furthermore, PBP‐NPs switch phenotypes of inflammatory macrophages in damaged organs and lower inflammation. Taken together, dual‐targeted induction of HO‐1 in fatty adipose and liver tissues is proven to be a promising therapeutic strategy to ameliorate obesity, insulin resistance, and steatohepatitis by lowering lipids and cytokines. [ABSTRACT FROM AUTHOR]

Abstract Purpose Psychological stress could negatively influence female reproductive ability. d‐Leucine (d‐Leu) is a d‐type amino acid found in foods and mammalian tissues. We have examined the protective effects of d‐Leu on oocyte abnormality induced by psychological stress. Methods Female mice (6‐week‐old) were divided into three groups: control, restraint stress (RS), and RS/d‐Leu. The RS and RS/d‐Leu mice were holed for 3 hours daily during 14 days. RS/d‐Leu mice were fed 0.3% d‐Leu diet. The oocyte maturation failure was analyzed by shapes of spindles and chromosomes. In addition, levels of heme‐oxygenase‐1 (HO‐1) and superoxide dismutase (SOD) expression in the ovaries were also examined. Whether d‐Leu reduces the generation of reactive oxygen species (ROS) in cultured cells, K562 cells were treated with d‐Leu, and then ROS in K562 were analyzed. Results Oocyte maturation failure was increased in RS mice. d‐Leu reduced abnormal oocytes to control level. The expression levels of HO‐1 and SOD2 increased in RS/d‐Leu mice compared to those of RS mice. ROS levels were decreased in K562 cells with d‐Leu in a dose‐dependent manner. Conclusions We concluded that d‐Leu protects oocytes from psychological stress through the induction of HO‐1 and SOD2 expression then by reducing oxidative stress.

Abstract Persistent uptake of high‐calorie diets induces the storage of excessive lipid in visceral adipose tissue. Lipids secreted from obese adipose tissue are accumulated in peripheral tissues such as the liver, pancreas, and muscle, and impair insulin sensitivity causing type 2 diabetes mellitus (T2DM). Furthermore, the accumulation of inflammatory cytokines and lipids in the liver induces apoptosis and fibrogenesis, and ultimately causes nonalcoholic steatohepatitis (NASH). To modulate obese tissue environments, it is challenged to selectively deliver inducers of heme oxygenase‐1 (HO‐1) to adipose tissue with the aid of a prohibitin targeting drug delivery system. Prohibitin binding peptide (PBP), an oligopeptide targeting prohibitin rich in adipose tissue, is conjugated on the surface of Hemin‐ or CoPP‐loaded poly(lactide‐co‐glycolide) nanoparticles (PBP‐NPs). PBP‐NPs efficiently differentiate lipid storing white adipocytes into energy‐generating brown adipocytes in T2DM and NASH models. In addition, PBP‐NPs are found to target prohibitin overexpressed fatty liver in the NASH model and inhibit hepatic uptake of circulating lipids. Furthermore, PBP‐NPs switch phenotypes of inflammatory macrophages in damaged organs and lower inflammation. Taken together, dual‐targeted induction of HO‐1 in fatty adipose and liver tissues is proven to be a promising therapeutic strategy to ameliorate obesity, insulin resistance, and steatohepatitis by lowering lipids and cytokines.

Beta-carotene (BC) is a well-known antioxidant. However, increasing evidence shows that under severe oxidative conditions, BC can become pro-oxidant, an effect that may be enhanced in the presence of iron (II). In our earlier studies, we observed that despite increasing heme oxygenase-1 (HO-1) levels in the heart, the protective effects of BC have been lost when it was used at a high concentration. Since iron releases from heme as a consequence of HO-1 activity, we hypothesized that the application of an iron-chelator (IC) would reverse the lost cardiac protection associated with an elevated HO-1 level. Thus, in the present study, we investigated the effects of desferrioxiamine (DFO) in isolated, ischemic/reperfused rat hearts after long-term treatment with vehicle or high-dose (HD) BC. Vehicle or 150 mg/bw kg daily doses of BC were administered to the rats for 4 weeks, and then their hearts were removed and subjected to 30 min of global ischemia (ISA) followed by 120 min of reperfusion (REP). During the experiments, cardiac function was registered, and at the end of the REP period, infarct size (IS) and HO-1 expression were measured. The results show that DFO treatment alone during REP significantly ameliorated postischemic cardiac function and decreased IS, although HO-1 expression was not increased significantly. In hearts isolated from BC-treated rats, no cardioprotective effects, despite an elevated HO-1 level, were observed, while DFO administration after ISA resulted in a mild improvement in heart function and IS. Our results suggest that iron could have a role whether BC exerts antioxidant or pro-oxidant effects in ISA/REP-injured hearts. [ABSTRACT FROM AUTHOR]

Purpose: Psychological stress could negatively influence female reproductive ability. d‐Leucine (d‐Leu) is a d‐type amino acid found in foods and mammalian tissues. We have examined the protective effects of d‐Leu on oocyte abnormality induced by psychological stress. Methods: Female mice (6‐week‐old) were divided into three groups: control, restraint stress (RS), and RS/d‐Leu. The RS and RS/d‐Leu mice were holed for 3 hours daily during 14 days. RS/d‐Leu mice were fed 0.3% d‐Leu diet. The oocyte maturation failure was analyzed by shapes of spindles and chromosomes. In addition, levels of heme‐oxygenase‐1 (HO‐1) and superoxide dismutase (SOD) expression in the ovaries were also examined. Whether d‐Leu reduces the generation of reactive oxygen species (ROS) in cultured cells, K562 cells were treated with d‐Leu, and then ROS in K562 were analyzed. Results: Oocyte maturation failure was increased in RS mice. d‐Leu reduced abnormal oocytes to control level. The expression levels of HO‐1 and SOD2 increased in RS/d‐Leu mice compared to those of RS mice. ROS levels were decreased in K562 cells with d‐Leu in a dose‐dependent manner. Conclusions: We concluded that d‐Leu protects oocytes from psychological stress through the induction of HO‐1 and SOD2 expression then by reducing oxidative stress. [ABSTRACT FROM AUTHOR]

Abstract Background Ischemia-reperfusion (I/R) is a critical pathophysiological basis of cognitive dysfunction caused by ischemia stroke. Heme-oxygenase-1 (HO-1) is the rate-limiting enzyme for the elimination of excessive free heme by combining with hemopexin (HPX), a plasma protein that contributes to eliminating excessive free heme during ischemia stroke. This study aimed to elucidate whether HPX could alleviate cognitive dysfunction in rats subjected to cerebral I/R. Methods Rats were randomly divided into five groups: sham, MCAO, Vehicle, HPX and HPX + protoporphyrin IX (ZnPPIX). Cerebral I/R was induced by MCAO. Saline, vehicle, HPX and HPX + ZnPPIX were injected intracerebroventricularly at the moment after reperfusion. Morris water maze (MWM) test was used to detect the learning and cognitive function. Western blot was used to detect the expression of HO-1 in ischemic penumbra. CD31/vWF double labeling immunofluorescence was used to detect the neovascularization in the penumbra hippocampus. The structure and function of blood-brain barrier (BBB) was detected by the permeability of Evans Blue (EB), water content of the brain tissue, the Ang1/Ang2 and VE-cadherin expression. Results Our study verified that HPX improved the learning and memory capacity. Hemopexin up-regulated HO-1 protein expression, the average vessel density in the penumbra hippocampus and the VE- cadherin expression but decreased the permeability of EB, the water content of brain tissue and the ratio of Ang1/Ang2. The effects were reversed by ZnPPIX, an inhibitor of HO-1. Conclusion HPX can maintain the integrity of the blood-brain barrier and alleviate cognitive dysfunction after cerebral I/R through the HO-1 pathway.

Beta-carotene (BC) is a well-known antioxidant. However, increasing evidence shows that under severe oxidative conditions, BC can become pro-oxidant, an effect that may be enhanced in the presence of iron (II). In our earlier studies, we observed that despite increasing heme oxygenase-1 (HO-1) levels in the heart, the protective effects of BC have been lost when it was used at a high concentration. Since iron releases from heme as a consequence of HO-1 activity, we hypothesized that the application of an iron-chelator (IC) would reverse the lost cardiac protection associated with an elevated HO-1 level. Thus, in the present study, we investigated the effects of desferrioxiamine (DFO) in isolated, ischemic/reperfused rat hearts after long-term treatment with vehicle or high-dose (HD) BC. Vehicle or 150 mg/bw kg daily doses of BC were administered to the rats for 4 weeks, and then their hearts were removed and subjected to 30 min of global ischemia (ISA) followed by 120 min of reperfusion (REP). During the experiments, cardiac function was registered, and at the end of the REP period, infarct size (IS) and HO-1 expression were measured. The results show that DFO treatment alone during REP significantly ameliorated postischemic cardiac function and decreased IS, although HO-1 expression was not increased significantly. In hearts isolated from BC-treated rats, no cardioprotective effects, despite an elevated HO-1 level, were observed, while DFO administration after ISA resulted in a mild improvement in heart function and IS. Our results suggest that iron could have a role whether BC exerts antioxidant or pro-oxidant effects in ISA/REP-injured hearts.

Background & aimsThe Keap1-Nrf2 signaling pathway regulates host cell defense responses against oxidative stress and maintains the cellular redox balance.MethodsWe investigated the function/molecular mechanisms by which Keap1-Nrf2 complex may influence liver ischemia/reperfusion injury (IRI) in a mouse model of hepatic cold storage (20h at 4°C) followed by orthotopic liver transplantation (OLT).ResultsThe Keap1 hepatocyte-specific knockout (HKO) in the donor liver ameliorated post-transplant IRI, evidenced by improved hepatocellular function and OLT outcomes (Keap1 HKO→Keap1 HKO; 100% survival), as compared with controls (WT→WT; 50% survival; p

Significance: Mucosal immunity in the gut has the important task of protecting an organism against potential danger, but at the same time of staying silent in response to harmless antigens present in the intestinal lumen. The delicate balance between immune activation and tolerance is referred to as gut homeostasis. Recent Advances: It has become clear that different types of immune cells and several factors participate in the maintenance of gut homeostasis, having as a final goal the prevention of non-necessary inflammation. Immune cells of the myeloid lineage, such as macrophages located in the lamina propria, represent the most abundant leukocyte population in the intestine and play a critical role in keeping the immune system silent, via the production of the anti-inflammatory cytokine interleukin-10. Critical Issues: Gut macrophages are an important source of the oxidative enzyme heme-oxygenase-1 (HO-1), which has crucial immune-modulatory properties. The protective role of HO-1 in the control of the intestinal inflammation, and its connection with the enteric flora have been demonstrated in experimental settings as well as in human biological samples. Future Directions: Loss of the gut homeostasis gives rise to conditions of acute inflammation that may degenerate into chronic disease, eventually leading to carcinogenesis. Understanding the mechanisms that regulate this enzyme will disclose novel therapeutic approaches that are designed to control chronic inflammation in the intestine. [ABSTRACT FROM AUTHOR]

Objective(s): The aim of this study was to investigate the effects of mild hypothermia on expression of NF-E2-related factor 2 (Nrf2) and heme-oxygenase-1 (HO-1) of rat cerebral cortex and hippocampus after cardiopulmonary resuscitation and further investigate the possible mechanism of action. Material and Methods:To copy an asphyxia heart arrest model, Sprague Dawley rats were randomly divided into normothermia group, mild hypothermia group before restoration of spontaneous circulation (ROSC), and mild hypothermia group after ROSC. Body temperature in normothermia group was maintained at 37.5-39℃, while in mild hypothermia group maintained at 32-34 °C by surface cooling with the ice pack. Each group then divided into three subgroups: 15 min, 30 min, and 60 min. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to detect the expression of Nrf2 and HO-1 mRNA in cerebral cortex and hippocampus. Hematoxylin-eosin (H&E) staining was performed to observe histological changes. Immunohistochemistry was performed to detect the expression of Nrf2 and HO-1 protein expression. Results: The expression of Nrf2 and HO-1 in cerebral cortex and hippocampus after cardiopulmonary resuscitation (CPR) was significantly increased and mild hypothermia up regulated this level. HE staining showed that mild hypothermia significantly improved neuronal injury. Conclusion: Mild hypothermia has neuroprotective effects on cerebral ischemia/reperfusion injury after cardiac arrest. The possible mechanism is that Nrf2-ARE pathway in cerebral cortex and hippocampus after CPR is activated.

Summary: Current treatments for systemic autoimmune diseases partially improve the health of patients displaying low pharmacological efficacy and systemic immunosuppression. Here, the therapeutic potential of transferring tolerogenic dendritic cells (tolDCs) generated with heme‐oxygenase inductor cobalt (III) protoporphyrin IX (CoPP), dexamethasone and rosiglitazone for the treatment of systemic autoimmunity was evaluated in two murine models of systemic lupus erythematosus (SLE), MRL‐Faslpr and NZM2410 mice. Dendritic cells treated ex vivo with these drugs showed a stable tolerogenic profile after lipopolysaccharide stimulation. Regular doses of tolDCs were administered to anti‐nuclear antibody‐positive mice throughout 60–70 days, and the clinical score was evaluated. Long‐term treatment with these tolDCs was well tolerated and effective to improve the clinical score on MRL‐Faslpr lupus‐prone mice. Additionally, decreased levels of anti‐nuclear antibodies in NZM2410 mice were observed. Although tolDC treatment increased regulatory T cells, no significant reduction of renal damage or glomerulonephritis could be found. In conclusion, these results suggest that the transfer of histone‐loaded tolDCs could improve only some SLE symptoms and reduced anti‐nuclear antibodies. This is the first study to evaluate antigen‐specific tolDC administration to treat SLE. Our report strengthens the clinical relevance of tolDC generation with CoPP, dexamethasone and rosiglitazone and the use of these modified cells as a therapy for systemic autoimmunity. [ABSTRACT FROM AUTHOR]

It has been demonstrated that cold atmospheric plasma (CAP) accelerates the wound healing process, however the underlying molecular pathways behind this effect remain unclear. Thus, the goal of the proposed investigation is to elucidate the therapeutic advantages of CAP on angiogenesis, pyroptotic, oxidative stress, and inflammatory mediators during the wound-healing mechanisms associated with diabetes. Intraperitoneal administration of streptozotocin (STZ, 60 mg/Kg) of body weight was used to induce type-1 diabetes. Seventy-five male mice were randomized into 3 groups: the control non-diabetic group, the diabetic group that was not treated, and the diabetic group that was treated with CAP. The key mediators of pyroptosis and its impact on the slow healing process of diabetic wounds were examined using histological investigations employing H&E staining, immunohistochemistry, ELISA, and Western blotting analysis. Angiogenesis proteins (VEGF, Ang-1, and HO-1) showed a significant decline in expression concentrations in the diabetic wounds, indicating that diabetic animals' wounds were less likely to heal. Furthermore, compared to the controls, the major mediators of pyroptosis (NLRP-3, IL-1β, and caspase-1), oxidative stress (iNOS and NO), and inflammation (TNF-α and IL-6) have higher expression levels in the diabetic wounds. These factors substantially impede the healing mechanism of diabetic wounds. Interestingly, our results disclosed the therapeutic impacts of CAP treatment in the healing process of diabetic wounds via significantly regulating the expression levels of angiogenesis, pyroptosis, oxidative stress and pro-inflammatory mediators. Our findings demonstrated the curative likelihood of CAP and the underlying mechanisms for enhancing the healing process of diabetic wounds. • Impaired and delayed wound healing is a serious complication of diabetes. • Diabetic mice exhibited impaired wound closure with impaired collagen deposition. • Impaired healing of diabetic wounds showed disruption of VEGF, HO-1, Ang-1 expression. • CAP accelerated the closure of diabetic wounds by decreasing the pyroptotic mediators. • CAP improved the healing of diabetic wounds by increasing the angiogenic mediators. [ABSTRACT FROM AUTHOR]

Nowadays, there is a growing interest in compounds derived from plants as potential raw materials for drug development. One of the most studied compounds is beta-carotene (BC). Several clinical studies can be found investigating the cardiovascular effects of BC, however, all these results are controversial. There is an increasing body of evidence showing that besides the well-known antioxidant properties, under strong oxidative circumstances, BC could become prooxidant as well. In this study, we investigated the effects of long-term, low- and high-dose BC treatment in ischemic/reperfused (ISA/REP) hearts isolated from Zucker diabetic fatty (ZDF) rats. The animals were treated with various daily doses of BC for 4 weeks and then hearts were isolated and subjected to 30 min of global ischemia (ISA) followed by 120 min of reperfusion (REP). Blood glucose levels were measured before, after two weeks, and at the end of the treatment. In isolated hearts, the myocardial function was registered. At the end of the reperfusion period, the infarct size (IS) and heme oxygenase-1 (HO-1) expression were measured. The results showed that a low dose of BC treatment significantly improved postischemic recovery, which was reflected in a decreased IS. Interestingly, when BC was applied at high concentrations, the observed protective effects were lost. Although BC treatment increased HO-1 expression, we did not observe a better heart function and/or decreased IS in the high-dose-treated group. Glucose tolerance tests showed a concentration-independent decrease in blood glucose levels. Our results suggest that long-term, low-dose BC treatment could be effective in the treatment of type-2-diabetes and related cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) induce nuclear factor erythroid 2–related factor 2 (Nrf2) activation as an adaptive defense mechanism, determining the synthesis of antioxidant molecules, including heme-oxygenase-1 (HO-1). HO-1 protects cells against oxidative injury, degrading free heme and inhibiting ROS production. HO-1 is highly expressed in macrophages during plaque growth. Macrophages are morpho-functionally heterogeneous, and the prevalence of a specific phenotype may influence the plaque fate. This heterogeneity has also been observed in monocyte-derived macrophages (MDMs), a model of macrophages infiltrating tissue. The study aims to assess oxidative stress status and Nrf2/HO-1 axis in MDM morphotypes obtained from healthy subjects and coronary artery disease (CAD) patients, in relation to coronary plaque features evaluated in vivo by optical coherence tomography (OCT). We found that MDMs of healthy subjects exhibited a lower oxidative stress status, lower Nrf2 and HO-1 levels as compared to CAD patients. High HO-1 levels in MDMs were associated with the presence of a higher macrophage content, a thinner fibrous cap, and a ruptured plaque with thrombus formation, detected by OCT analysis. These findings suggest the presence of a relationship between in vivo plaque characteristics and in vitro MDM profile, and may help to identify patients with rupture-prone coronary plaque.

Carbon monoxide-releasing molecule (CORM-2) acts as a carbon monoxide (CO) deliverer in a more controlled manner without altering carboxyhemoglobin level and exerts potential function in inhibiting inflammation and/or acute nociception. However, the regulatory mechanism of CORM-2 on spinal nerve ligation (SNL)-induced neuropathic pain is not currently clear. Our study aims to investigate the role of CORM-2 in neuropathic pain and the underlying mechanism. We found that spinal cord astrocytes were dramatically activated on day 7 after SNL. L-α-aminoadipate (L-α-AA), an astroglial toxin, reversed SNL-induced astrocyte activation at sub-toxic dose. Intrathecal administration of CO donor CORM-2 induced antiallodynic and antihyperalgesic effects in neuropathic animals induced by SNL and suppressed SNL-induced spontaneous excitatory postsynaptic current (EPSC) frequency in lamina II neurons of spinal cord slices. CORM-2 administration markedly inhibited SNL-induced connexin 43 (Cx43) expression, hemichannel function, and gap junction function on spinal astrocyte membranes. Moreover, exogenous CORM-2 could attenuate HO-1 expression, while overexpressed heme oxygenase-1 (HO-1) increased intracellular CO production, attenuated Cx43 expression, hemichannel function, and gap junction function on spinal astrocyte membranes. Additionally, Cx43 over-expression markedly reduced CORM-2-induced mechanical threshold and thermal hyperalgesia and elevated CORM-2-induced spontaneous EPSC frequency. In conclusion, CORM-2 attenuated SNL-induced neuropathic pain via suppressing Cx43-hemichannel function, which may contribute to understanding of the pathology of neuropathic pain. [ABSTRACT FROM AUTHOR]

Aims: A loss in brain acetylcholine and cholinergic markers, subchronic inflammation, and impaired mitochondrial function, which lead to low-energy production and high oxidative stress, are common pathological factors in several neurodegenerative diseases (NDDs). Glial cells are important for brain homeostasis, and microglia controls the central immune response, where α7 acetylcholine nicotinic receptors (nAChR) seem to play a pivotal role; however, little is known about the effects of this receptor in metabolism. Therefore, the aim of this study was to evaluate if glial mitochondrial energetics could be regulated through α7 nAChR. Results: Primary glial cultures treated with the α7 nicotinic agonist PNU282987 increased their mitochondrial mass and their mitochondrial oxygen consumption without increasing oxidative stress; these changes were abolished when nuclear erythroid 2-related factor 2 (Nrf2) was absent, heme oxygenase-1 (HO-1) was inhibited, or peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) was silenced. More specifically, microglia of animals treated intraperitoneally with the α7 nAChR agonist PNU282987 (10 mg/kg) showed a significant increase in mitochondrial mass. Interestingly, LysMcre-Hmox1Δ/Δ and PGC-1α−/− animals showed lower microglial mitochondrial levels and treatment with PNU282987 did not produce effects on mitochondrial levels. Innovation: Increases in microglial mitochondrial mass and metabolism can be achieved via α7 nAChR by a mechanism that implicates Nrf2, HO-1, and PGC-1α. This signaling pathway could open a new strategy for the treatment of NDDs, such as Alzheimer's, characterized by a reduction of cholinergic markers. Conclusion: α7 nAChR signaling increases glial mitochondrial mass, both in vitro and in vivo, via HO-1 and PCG-1α. These effects could be of potential benefit in the context of NDDs. Antioxid. Redox Signal. 27, 93-105. [ABSTRACT FROM AUTHOR]

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Objective To investigate the role of human host heme-oxygenase-1 (HO-1) in pathogenesis of cerebral malaria in the in vitro model. Methods The effect of human host HO-1 [human brain microvascular endothelial cell (HBMEC)] on hemoglobin degradation in the co-culture model of HBMEC and ITG Plasmodium falciparum -infected red cells (iRBC) through measurement of the enzymatic products iron and bilirubin. Results Following exposure to the HO-1 inducer CoPPIX at all concentrations, the HBMEC cells apoptosis occurred, which could be prominently observed at 15 μM of 3 h exposure. In contrast, there was no significant change in the morphology in the non-exposed iRBC at all concentrations and exposure time. This observation was in agreement with the levels of the enzymatic degradation products iron and bilirubin, of which the highest levels (106.03 and 1753.54% of baseline level, respectively) were observed at 15 μM vs . 20 μM at 3 h vs . 24 h exposure. For the effect of the HO-1 inhibitor ZnPPIX, HBMEC cell morphology was mostly unchanged, but significant inhibitory effect on cell apoptosis was seen at 10 μM for the exposure period of 3 h (37.17% of baseline level). The degree of the inhibitory effect as reflected by the level of iron produced was not clearly observed (highest effect at 10 μM and 3 h exposure). Conclusions Results provide at least in part, insight into the contribution of HO-1 on CM pathogenesis and need to be confirmed in animal model. [ABSTRACT FROM AUTHOR]

Objective: This study evaluated the ability of heme oxygenase-1 to prevent or reverse renal fibrosis. Methods: Sprague-dawley male rats were submitted to unilateral ureteral obstruction and divided into groups: non-treated and hemin. Biochemical and histological analyses were performed. We also conducted RT-PCR to verify the expression of heme oxygenase-1, MCP-1, IL1-β, IL-6, TNF-α, COL-I, COL-III, PAI-1 and fibronectin mRNA. Rresults: heme oxygenase-1 expression significantly increased in treated animals. The non treated group showed significantly higher levels of proteinuria than the Hemin group. The protein/urinary creatinine ratio in obstructed pelvis was also higher in non treated group, which also showed greater albuminuria and higher percentage of fibrosis when compared to the Hemin group. The expression of pro-inflammatory and pro-fibrotic molecules was significantly higher in the non treated group. Cconclusions: The treatment induced the expression of heme oxygenase-1, preventing the installation of fibrosis and even limiting its progression.

Phthalates as a large group of environmental pollutants are used primarily as plasticizers and solvents, which have become a growing problem worldwide. Epidemiological results show that severity of heart disease is related to degree of environmental contamination. As the most usually used phthalate, di(2-ethylhexyl) phthalate (DEHP) has toxic effects on organism health and is also a major cause of heart damage. Ingestion of food, liquid, or dust contaminated with DEHP are major routes of exposure. The purpose of the present research was to determine the mechanism of cardiotoxicity in mice after exposure to DEHP. Here, male mice were treated by gavage with three different doses of (50, 200 and 500 mg/kg b.w.) DEHP for 28 days. Our research showed that DEHP brought about histopathological changes involving cardiomyocyte lysis and rupture, and ultrastructural damage such as dissolution and loss of mitochondrial cristae. Furthermore, DEHP induced oxidative stress and a significant decline in the antioxidant function, which activates nuclear factor E2-related factor 2 (Nrf2)/heme-oxygense-1 (HO-1) signaling pathways. Interestingly, DEHP resulted in lipid peroxidation and increased ferrous ion content, suggesting that ferroptosis occurred in mouse hearts. Therefore, our findings demonstrated that DEHP could induce cardiac ferroptosis via upregulation of HO-1. The present study provides novel evidence of HO-1 as a target for DEHP-induced cardiotoxicity. DEHP is a difficult-to-degrade organic pollutant that easily migrates into the environment and accumulates. The present study shows that DEHP can cause cardiotoxicity, including oxidative stress injury and ferroptosis, whereas HO-1 is a target of DEHP-induced ferroptosis in mouse cardiomyocytes. [Display omitted] [ABSTRACT FROM AUTHOR]

Cisplatin-induced testicular damage is a major obstacle in the application of cisplatin as chemotherapeutic agent. However, it remains as one of the most widely employed anticancer agents in treating various solid tumors including prostate cancer. Since heme-oxygenase-1 (HO-1) is a cytoprotective enzyme with anti-oxidative stress, anti-inflammatory and anticancer activities, we investigated the effects of up-regulation of HO-1 by hemin and its inhibition by zinc protoporphyrin-IX (ZnPP) on cisplatin-induced testicular toxicity in adult rats. Furthermore, the anticancer effect of hemin and ZnPP, with and without cisplatin, was evaluated on human prostate cancer cell line, PC3. Results of the animal study showed that hemin reversed cisplatin-induced perturbations in sperm characteristics, normalized serum testosterone level, and ameliorated cisplatin-induced alterations in testicular and epididymal weights, and restored normal testicular architecture. Moreover, hemin increased the expression and activity of HO-1 protein and prevented cisplatin-induced testicular toxicity by virtue of its antioxidant and anti-inflammatory effects. This effect was evidenced by amelioration of testicular oxidative stress markers (malondialdehyde, nitric oxide, reduced glutathione contents, and catalase activity) and inflammatory mediators (tumor necrosis factor-α and nitric oxide synthase expressions). In contrast, administration of ZnPP (HO-1 inhibitor) did not show significant improvement against cisplatin-induced testicular toxicity. Finally, in vitro analyses showed that, hemin augmented the anticancer efficacy of cisplatin, while ZnPP inhibited its apoptotic effect in PC3 cells. In conclusion, the induction of HO-1 represents a potential therapeutic approach to protect the testicular tissue from the detrimental effects of cisplatin without repressing, but rather augmenting, its cytotoxic effects on PC3 cells. [ABSTRACT FROM AUTHOR]

Heme oxygenase-1 (HO-1) is a stress-inducible cytoprotective enzyme. It is often overexpressed in different types of cancers and promotes cell survival. However, the role of HO-1 and the underlying molecular mechanism of cadmium (Cd)-induced oxidative stress in cancer cells remain undefined. Here we show that the role of HO-1 under Cd-induced oxidative stress is dependent upon autophagy, which is sensitized by the tumor suppressor p53. The sensitivity to Cd was 3.5- and 14-fold higher in p53-expressing YD8 and H460 cells than in p53-null YD10B and H1299 cells, respectively. The levels of p53 in YD8 and H460 cells decreased in a Cd concentration-dependent manner, which was inhibited by pretreatment with N -acetylcysteine. In both cell lines, Cd exposure resulted in caspase-3-mediated PARP-1 cleavage and the induction of CHOP, LC3-II, and HO-1, which were limited in YD10B and H1299 cells exposed to high concentrations of Cd. Cd exposure to p53-overexpressing YD10B cells enhanced Cd-induced HO-1 and LC3-II levels, whereas genetic knockdown of p53 in YD8 cells resulted in the suppression of Cd-induced levels of HO-1 and LC3-II, indicating that p53 is required in the sensing of HO-1 and induction of autophagy. The inhibition of autophagy using small interfering RNA (siRNA) for the autophagy-related gene atg 5 enhanced HO-1, CHOP, and PARP-1 cleavage induced by Cd. However, transfection with HO-1 siRNA increased Cd-induced LC3-II, and suppressed the expression of CHOP and cleavage of PARP-1. Collectively, the role of HO-1 in apoptosis could be modulated by autophagy, which is sensitized by p53 expression in human cancer cell lines. [ABSTRACT FROM AUTHOR]

Metal ion release and accumulation is considered to be a factor responsible for the high failure rates of metal-on-metal (MoM) hip implants. Numerous studies have associated the presence of these ions, besides other factors, including a hypoxia-like response and changes in pH due to metal corrosion leading to the induction of the oxidative stress response. The aim of the present study was to verify whether, in patients with a MoM hip prosthesis, mRNA and protein expression of HMOX-1 was modulated by the presence of metal ions and whether patients without prostheses exhibit a different expression pattern of this enzyme. The study was conducted on 22 matched pairs of patients with and without prostheses, for a total of 44 samples. Ion dosage was determined using inductively coupled plasma mass spectrometry equipped with dynamic cell reaction. HMOX-1 gene expression was quantified by reverse transcription-quantitative polymerase chain reaction and HMOX-1 protein expression was analyzed using an enzyme-linked immunosorbent assay. The results demonstrated that although there were significant differences in the metallic ion concentrations amongst the two groups of patients, there was no correlation between circulating levels of cobalt (Co) and chromium (Cr), and HMOX-1 gene and protein expression. Additionally, there was no significant difference in the protein expression levels of HMOX-1 between the two groups. In conclusion, it was demonstrated that circulating Co and Cr ions released by articular prosthetics do not induce an increase in HMOX-1 mRNA and protein expression at least 3.5 years after the implant insertion. The present study suggests that involvement of HMOX-1 may be excluded from future studies and suggests that other antioxidant enzymes, including superoxide dismutase, glutathione peroxidase and reductase should be investigated. [ABSTRACT FROM AUTHOR]

β-carotene (BC), a lipid-soluble tetraterpene precursor to vitamin A, widely distributed in plants, including many used in human diet, has well-known health-enhancing properties, including reducing risk of and treatment for certain diseases. Nevertheless, BC may also act to promote disease through the activity of BC derivatives that form in the presence of external toxicants such as cigarette smoke and endogenously-produced reactive oxygen species. The present investigation evaluates the dose-dependent cardioprotective and possibly harmful properties of BC in a rat model. Adult male rats were gavage-fed BC for 4 weeks, at dosages of either 0, 30 or 150 mg/kg/day. Then, hearts excised from the animals were mounted in a “working heart” apparatus and subjected to 30 min of global ischemia, followed by 120 min of reperfusion. A panel of cardiac functional evaluations was conducted on each heart. Infarct size and total antioxidant capacity of the myocardium were assessed. Heart tissue content of heme oxygenase-1 (HO-1) by Western blot analysis; and potential direct cytotoxic effects of BC by MTT assay were evaluated. Hearts taken from rats receiving 30 mg/kg/day BC exhibited significantly improved heart function at lower reperfusion times, but lost this protection at higher BC dosage and longer reperfusion times. Myocardial HO-1 content was significantly elevated dose-responsively to both BC dosage. Finally, in vitro evaluation of BC on H9c2 cells showed that the agent significantly improved vitality of these cells in a dose range of 2.5–10 μM. Although data presented here do not allow for a comprehensive mechanistic explanation for reduced cardioprotection at high dose BC, it is speculated that since Fe 2+ produced as a metabolite of HO-1 activity, may determine whether BC acts as an antioxidant or prooxidant agent, the strong induction of this enzyme in response to ischemia/reperfusion-induced oxidative stress may account for the high-dose BC loss of cardioprotection. [ABSTRACT FROM AUTHOR]

Prediabetes and diabetes are rising worldwide. Control of blood glucose is crucial to prevent or delay diabetic complications that frequently result in increased morbidity and mortality. Most strategies include medical treatment and changes in lifestyle and diet. Some nutraceutical compounds have been recognized as adjuvants in diabetes control. Many of them can activate the nuclear factor (erythroid-derived 2)-like 2 (Nrf2), which has been recognized as a master regulator of the antioxidant response. Recent studies have described the role of Nrf2 in obesity, metabolic syndrome, nephropathy, retinopathy and neuropathy, where its activation prevents the development of diabetes and its complications. It has been demonstrated that natural compounds derived from plants, vegetables, fungi and micronutrients (such as curcumin, sulforaphane, resveratrol and vitamin D among others) can activate Nrf2 and, thus, promote antioxidant pathways to mitigate oxidative stress and hyperglycemic damage. The role of some natural Nrf2 activators and its effect in diabetes is discussed. [ABSTRACT FROM AUTHOR]

Glyphosate-based herbicides are the most frequently used herbicides in the world. We evaluated the effect of Roundup 360 SL on the expression of interleukin-1β ( il- 1β), interleukin-10 ( il- 10) and heme-oxygenase-1 ( ho- 1) in the gills, intestines and spleen of young European sea bass ( Dicentrachus labrax L.), aged 8 mo. A group of fish was exposed to 647 mg/L of Roundup for 96 h. This treatment did not alter gene expression levels of il-1β and il- 10 cytokine in the intestines, but significantly lowered both levels in the gills ( p = 0.02 and p = 0.04 respectively). Expression levels of ho- 1 were increased significantly in the three organs of fish from the treated group (the gills p = 0.04, the intestines p = 0.004 and the spleen p < 0.001). These changes may in turn negatively impact the immune system of European sea bass exposed to Roundup. [ABSTRACT FROM AUTHOR]

Ischemia reperfusion injury (IRI) contributes to partial flap and solid organ transplant failure. Heme-oxygenase 1 (HO-1) is an inducible, cytoprotective enzyme which protects against IRI in solid organ transplant models. Heme arginate (HA), a HO-1 inducer, is a promising, translatable, preconditioning agent. This study investigated the effects of preconditioning with HA on the clinical outcome of a myocutaneous IRI model. Forty male Lewis rats were randomized to intravenously receive 1) Control-NaCl, 2) HA, 3) HA and tin mesoporphyrin (SnMP), a HO-1 inhibitor; and 4) SnMP alone. Twenty-four hours later, an in situ transverse rectus abdominis myocutaneous flap was performed under isoflurane anesthesia. Viability of flaps was measured clinically and by laser-Doppler perfusion scanning. In vitro work on human epidermal keratinocytes (HEKa) assessed the effects of HA, SnMP, and the iron chelator desferrioxamine on 1) cytotoxicity, 2) intracellular reactive oxygen species (ROS) concentration, and 3) ROS-mediated DNA damage. In contrast to our hypothesis, HA preconditioning produced over 30% more flap necrosis at 48 h compared with controls (P = 0.02). HA-containing treatments produced significantly worse flap perfusion at all postoperative time points. In vitro work showed that HA is cytotoxic to keratinocytes. This cytotoxicity was independent of HO-1 and was mediated by the generation of ROS by free heme. In contrast to solid organ data, pharmacological preconditioning with HA significantly worsened clinical outcome, thus indicating that this is not a viable approach in free flap research. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to explore the influence of the renin–angiotensin system on cardiac prooxidants and antioxidants levels and its association to autonomic imbalance induced by hyperthyroidism. Male Wistar rats were divided into four groups: control, losartan (10mg/kg/day by gavage, 28day), thyroxine (T4) (12mg/L in drinking water for 28days), and T4+losartan. Spectral analysis (autonomic balance), angiotensin II receptor (AT1R), NADPH oxidase, Nrf2 and heme-oxygenase-1 (HO-1) myocardial protein expression, and hydrogen peroxide (H2O2) concentration were quantified. Autonomic imbalance induced by hyperthyroidism (~770%) was attenuated in the T4+losartan group (~32%) (P<0.05). AT1R, NADPH oxidase, H2O2, as well as concentration, Nrf2 and HO-1 protein expression were elevated (~172%, 43%, 40%, 133%, and 154%, respectively) in T4 group (P<0.05). H2O2 and HO-1 levels were returned to control values in the T4+losartan group (P<0.05). The overall results demonstrate a positive impact of RAS blockade in the autonomic control of heart rate, which was associated with an attenuation of H2O2 levels, as well as with a reduced counter-regulatory response of HO-1 in experimental hyperthyroidism. [Copyright &y& Elsevier]

Abstract: Excessive generation of free radicals is regarded as a major detrimental factor in cerebral ischemic insults. Neurons are particularly vulnerable to oxidative stress due to their limited anti-oxidant capacity. As an important source of antioxidants in the brain, astroglia are now thought to be attractive targets for pharmacological interventions to reduce neuronal oxidative stress in ischemic stroke. In the present study, we synthesized a novel antioxidant, the (1S)-(-)-verbenone derivative LMT-335, and investigated its anti-ischemic activities. In rat cortical neuronal/glial co-cultures, LMT-335 significantly reduced oxygen–glucose deprivation (OGD)/reoxygenation (R)-induced neuronal injury. Although it did not inhibit N-methyl-d-aspartate-induced excitotoxicity, LMT-335 significantly reduced OGD/R-evoked intracellular oxidative stress. However, the oxygen radical absorbance capacity assay and 1,1-diphenyl-2-picrylhydrazyl assay showed that the free radical scavenging activities of LMT-335 were lower than those of trolox. Instead, LMT-335 significantly increased the astroglial expression of heme oxygenase-1 (HO-1), a well-known anti-oxidant stress protein, as evidenced by immunocytochemistry and immunoblot analyses. Moreover, a selective HO-1 inhibitor, tin protoporphyrin IX (SnPP), significantly blocked the anti-ischemic effect of LMT-335. The present findings indicate that LMT-335 exerts neuroprotective effects against OGD/R by up-regulation of HO-1 in astroglial cells. Our data suggest that astroglial HO-1 represents a potential therapeutic target for the treatment of ischemic stroke. [Copyright &y& Elsevier]

Abstract: While changes in heme oxygenase (HO-1) in lung cancer have already been reported, conflicting results were obtained for enzyme expression in human lung cancer specimens. Therefore, the aim of this work was to study HO-1 expression in a large collection of human lung cancer samples. For this purpose, we analyzed the expression of HO-1 in an organized tissue microarray (TMA) and investigated its correlation with clinicopathological data. Ninety-six percent of tumor samples were positive for HO-1, and the expression of HO-1 was significantly higher in cancerous than in non-cancerous tissues. Importantly, HO-1 expression correlated with advanced stages and lymph node involvement. Additionally, quantitative RT-PCR in 18 pairs of human lung carcinomas and their adjacent non-malignant tissues was performed. Our results demonstrate that HO-1 protein is upregulated in epithelial malignant cells in NSCLC and its expression is associated with higher stages of the disease. Additionally, different subcellular localization is observed between tumor and adjacent non-malignant tissues. [Copyright &y& Elsevier]

Abstract: Increased placental oxidative stress in preeclampsia (PE) has been associated in part to a decrease in glutathione peroxidase (GPX) antioxidant activity. However, it is not clear if GPX mRNA expression is affected in PE, and how the presence of labor may impair this expression. In this study, we characterized by quantitative PCR, in situ hybridization and immunohistochemistry, the expression of four GPX (GPX1 to 4) in the placenta of normotensive (NP; n = 23) and PE pregnancies (n = 25) according to mode of delivery: vaginal delivery (with labor) or cesarean (without labor); the tissue layer: amnion-chorion (AC) and villi; and the sampling site: peri-insertion or peripheral. Concomitantly, oxidative stress markers mRNA expression, HSP70 and HO-1 were measured. All GPX mRNA and protein were detected in all layers of the placenta and sampling sites. In absence of labor, GPX1 is more expressed near the umbilical cord than at the periphery of the villi (p = 0.037). At the periphery of AC membranes, GPX2 was more expressed in PE than in controls in presence of labor (p = 0.037). Interestingly, GPX4 mRNA level was clearly deficient in the PE villi in presence or absence of labor (p < 0.0473). Also, the GPX4 expression in PE was lower than controls in AC membranes in presence of labor (p = 0.0007). Oxidative stress markers, HSP70 and HO-1, were higher in PE placental membranes than in controls in absence of labor (p < 0.011). HSP70 was also upregulated in PE placental membranes in presence of labor (p = 0.034). Correlations between stress markers and GPX mRNA expression were mostly present in AC membranes in presence of labor in NP. Most of the latter correlations were lost in PE. In conclusion, our results suggest that the reported decrease in GPx activity and increased oxidative stress in PE placental villi may be attributed in part to GPX4 independently of the presence or absence of labor. [Copyright &y& Elsevier]

Abstract: Ferulic acid (FA) is a phenolic compound whose neuroprotective activity was extensively studied in vitro. In this study, we provided functional in vivo evidence that FA limits noise-induced hearing loss. Guinea-pigs exposed to acoustic trauma for 1 h exhibited a significant impairment in auditory function; this injury was evident as early as 1 day from noise exposure and persisted over 21 days. Ferulic acid (150 mg/kg i.p. for 4 days) counteracted noise-induced hearing loss at days 1, 3, 7 and 21 from noise exposure. The improvement of auditory function by FA was paralleled by a significant reduction in oxidative stress, apoptosis and increase in hair cell viability in the organ of Corti. Interestingly in the guinea-pig cochleae, the neuroprotective effect of FA was functionally related not only to its scavenging ability in the peri-traumatic period but also to the up-regulation of the cytoprotective enzyme heme oxygenase-1 (HO-1); in fact, FA-induced improvement of auditory function was counteracted by the HO inhibitor zinc-protoporphyrin-IX and paralleled the time-course of HO-1 induction over 3–7 days. These results confirm the antioxidant properties of FA as free-radical scavenger and suggest a role of HO-1 as an additional mediator against noise-induced ototoxicity. [ABSTRACT FROM AUTHOR]

Abstract: Sofalcone, 2′-carboxymethoxy-4,4-bis(3-methyl-2-butenyloxy)chalcone, is an anti-ulcer agent that is classified as a gastric mucosa protective agent. Recent studies indicate heat shock proteins such as HSP32, also known as heme-oxygenase-1(HO-1), play important roles in protecting gastrointestinal tissues from several stresses. We have previously reported that sofalcone increases the expression of HO-1 in adipocytes and pre-adipocytes, although the effect of sofalcone on HO-1 induction in gastrointestinal tissues is not clear. In the current study, we investigated the effects of sofalcone on the expression of HO-1 and its functional role in rat gastric epithelial (RGM-1) cells. We found that sofalcone increased HO-1 expression in RGM-1 cells in both time- and concentration-dependent manners. The HO-1 induction was associated with the nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in RGM-1 cells. We also observed that sofalcone increased vascular endothelial growth factor (VEGF) production in the culture medium. Treatment of RGM-1 cells with an HO-1 inhibitor (tin-protoporphyrin), or HO-1 siRNA inhibited sofalcone-induced VEGF production, suggesting that the effect of sofalcone on VEGF expression is mediated by the HO-1 pathway. These results suggest that the gastroprotective effects of sofalcone are partly exerted via Nrf2-HO-1 activation followed by VEGF production. [ABSTRACT FROM AUTHOR]

Abstract: Particulate matter (PM) has been the primary focus of studies aiming to understand the relationship between the chemical properties of ambient aerosols and adverse health effects. Size and chemical composition of PM have been linked to their oxidative capacity which has been postulated to promote or exacerbate pulmonary and cardiovascular diseases. But in the last few years, new studies have suggested that volatile and semi-volatile components may also contribute to many adverse health effects. The objectives of this study were: (i) assess for the first time the redox and electrophilic potential of vapor-phase components of ambient aerosols and (ii) evaluate the relative contributions of particle- and vapor-fractions to the hazard of a given aerosol. To achieve these objectives vapor- and particle-phase samples collected in Riverside (CA) were subjected to three chemical assays to determine their redox and electrophilic capacities. The results indicate that redox active components are mainly associated with the particle-phase, while electrophilic compounds are found primarily in the vapor-phase. Vapor-phase organic extracts were also capable of inducing the stress responding protein, heme-oxygenase-1 (HO-1), in RAW264.7 murine macrophages. These results demonstrate the importance of volatile components in the overall oxidative and electrophilic capacity of aerosols, and point out the need for inclusion of vapors in future health and risk assessment studies. [Copyright &y& Elsevier]

Background: The triggers and cellular mechanisms of cardiac dysfunction have not been clearly established during the early period following challenge with lipopolysaccharides (LPS) (<1 h post-LPS). The aim of the study was to evaluate the myocardial depression during early stage of endotoxemia, the relationship between oxidative stress production and cardiac dysfunction in a rat model of endotoxic shock, and its inhibition by heme-oxygenase-1 (HO-1) overexpression. Materials and Methods: LPS-induced myocardial deformation was assessed by tissue Doppler imaging and invasive hemodynamic measurements in rats 2 h after LPS challenge. Myocardial samples were processed for the measurements of tumor necrosis factor alpha (TNFα), nitric oxidase synthase II (NOSII), HO-1 gene expression, reactive oxygen species (ROS) production, and reduced glutathione/oxidized glutathione (GSH/GSSH) ratio. Results: Myocardial systolic and diastolic deformation was evident as determined by tissue Doppler imaging but left ventricular conventional echocardiographic parameters did not show significant alterations. Myocardial deformation was significantly associated with reactive oxygen species and TNFα overproduction. Pretreatment with hemin to induce HO-1 resulted in decreased oxidative stress and TNFα production, and prevented LPS-induced alterations in myocardium. Conclusions: These preliminary results suggest myocardial alteration at a very early stage after LPS challenge associated with oxidative stress response. Manipulation of the HO-1 pathway may represent a future therapeutic strategy to counteract oxidative stress of endotoxemia and perhaps may limit future myocardial deformation. [Copyright &y& Elsevier]

Infection by Plasmodium, the causative agent of malaria, is associated with hemolysis and therefore with release of hemoglobin from RBC. Under inflammatory conditions, cell-free hemoglobin can be oxidized, releasing its heme prosthetic groups and producing deleterious free heme. Here we demonstrate that survival of a Plasmodium-infected host relies strictly on its ability to prevent the cytotoxic effects of free heme via the expression of the hemecatabolyzing enzyme heme oxygenase-1 (HO-1; encoded by the Hmox1 gene). When infected with Plasmodium chabaudichabaudi (Pcc), wild-type (Hmox1+/+) BALB/c mice resolved infection and restored homeostasis thereafter (0% lethality). In contrast, HO-1 deficient (Hmox1-/- BALB/c mice developed a lethal form of hepatic failure (100% lethality), similar to the one occurring in Pcc-infected DBA/2 mice (75% lethality). Expression of HO-1 suppresses the pro-oxidant effects of free heme, preventing it from sensitizing hepatocytes to undergo TNF-mediated programmed cell death by apoptosis. This cytoprotective effect, which inhibits the development of hepatic failure in Pcc-infected mice without interfering with pathogen burden, is mimicked by pharmacological antioxidants such as N-acetylcysteine (NAC). When administered therapeutically, i.e., after Pcc infection, NAC suppressed the development of hepatic failure in Pcc-infected DBA/2 mice (0% lethality), without interfering with pathogen burden. In conclusion, we describe a mechanism of host defense against Plasmodium infection, based on tissue cytoprotection against free heme and limiting disease severity irrespectively of parasite burden. [ABSTRACT FROM AUTHOR]

Abstract: Sofalcone, 2′-carboxymethoxy-4,4′-bis(3-methyl-2-butenyloxy)chalcone, has been used as an anti-ulcer agent, although its precise molecular mechanism has not been completely understood. In the current study, we tested the effects of sofalcone on the inflammatory crosstalk between macrophages and adipocytes and on the differentiation of pre-adipocytes. We found that sofalcone has a strong suppressive effect on the production of nitric oxide (NO), tumor necrosis factor (TNF)α, and monocyte chemoattractant protein (MCP)-1 in the culture medium of a coculture system containing RAW264.7 macrophages and 3T3-F442A adipocytes stimulated with lipopolysaccharide (LPS). The suppressive effect of sofalcone on NO production was attenuated by treatment with tin-protoporphyrin (SnPP), a heme-oxygenase (HO)-1 inhibitor. Western blotting analysis showed that sofalcone increased HO-1 expression in both 3T3-F442A mature adipocytes and undifferentiated fibroblasts. Sofalcone also inhibited the differentiation of 3T3-F442A pre-adipocytes into adipocytes, which was restored by SnPP treatment. These results suggest that sofalcone has preferable properties for obesity or metabolic syndrome. [Copyright &y& Elsevier]

Depending on its concentration, nitric oxide (NO) has beneficial or toxic effects. In pathological conditions, NO reacts with superoxide to form peroxynitrite, which nitrates proteins forming nitrotyrosine residues (3NY), leading to loss of protein function, perturbation of signal transduction, and cell death. 3NY immunoreactivity is present in many CNS diseases, particularly multiple sclerosis. Here, using the high flux NO donor, spermine-NONOate, we report that oligodendrocytes are resistant to NO, while motor neurons are NO sensitive. Motor neuron sensitivity correlates with the NO-dependent formation of 3NY, which is significantly more pronounced in motor neurons when compared with oligodendrocytes, suggesting peroxynitrite as the toxic molecule. The heme-metabolizing enzyme, heme-oxygenase-1 (HO1), is necessary for oligodendrocyte NO resistance, as demonstrated by loss of resistance after HO1 inhibition. Resistance is reinstated by peroxynitrite scavenging with uric acid further implicating peroxynitrite as responsible for NO sensitivity. Most importantly, differential sensitivity to NO is also present in cultures of primary oligodendrocytes and motor neurons. Finally, motor neurons cocultured with oligodendrocytes, or oligodendrocyte-conditioned media, become resistant to NO toxicity. Preliminary studies suggest oligodendrocytes release a soluble factor that protects motor neurons. Our findings challenge the current paradigm that oligodendrocytes are the exclusive target of multiple sclerosis pathology. [ABSTRACT FROM AUTHOR]

The clinical utility of anthracycline anticancer agents, especially doxorubicin (DOX), is limited by progressive toxic cardiomyopathy linked to cardiomyocyte apoptosis. This study examined the protective effects of CO and bilirubin on DOX-induced cardiomyocyte toxicity. In vitro, DOX significantly decreased the viability of H9c2 cells and increased apoptotic features, such as changes in nuclear morphology and caspase protease activation. CO and bilirubin significantly inhibited DOX-induced cell death and caspase-3 activation, which may be explained by increased Bcl-2 expression and inhibition of Bax expression. CO and bilirubin up-regulated the heme oxygenase-1 (HO-1), which was required for the protective effect of CO, and a single bilirubin treatment increased DOX-induced apoptosis in H9c2 cells. The inhibition of HO-1 with ZnPP resulted in a striking increase in apoptosis in the CO, bilirubin, and DOX-treated cells. Furthermore, HO-1 overexpression increased resistance against DOX-induced cytotoxicity in H9c2 cells. In conclusion, CO and bilirubin can inhibit DOX-induced apoptosis in H9c2 cardiomyocytes. These findings imply that the therapeutic index of anthracycline cancer chemotherapeutics can be improved by protecting against cardiomyocyte death. [ABSTRACT FROM AUTHOR]

Chronic or intermittent extravasations of blood into the subarachnoid space, and dissemination of heme by circulating cerebrospinal fluid, are the only established causes of superficial siderosis of the central nervous system (CNS). We studied the autopsy tissues of nine patients by iron histochemistry, immunocytochemistry, single- and double-label immunofluorescence, electron microscopy of ferritin, and high-definition X-ray fluorescence. In one case, frozen brain tissue was available for quantitative assay of total iron and ferritin. Siderotic tissues showed extensive deposits of iron and ferritin, and infiltration of the cerebellar cortex was especially severe. In addition to perivascular collections of hemosiderin-laden macrophages, affected tissues displayed iron-positive anuclear foamy structures in the neuropil that resembled axonal spheroids. They were especially abundant in eighth cranial nerves and spinal cord. Double-label immunofluorescence of the foamy structures showed co-localization of neurofilament protein and ferritin but comparable merged images of myelin-basic protein and ferritin, and ultrastructural visualization of ferritin, did not allow the conclusion that axonopathy was simply due to dilatation and rupture of fibers. Heme-oxygenase-1 (HO-1) immunoreactivity persisted in macrophages of siderotic cerebellar folia. Siderosis caused a large increase in total CNS iron but high-definition X-ray fluorescence of embedded tissue blocks excluded the accumulation of other metals. Holoferritin levels greatly exceeded the degree of iron accumulation. The susceptibility of the cerebellar cortex is likely due to Bergmann glia that serve as conduits for heme; and the abundance of microglia. Both cell types biosynthesize HO-1 and ferritin in response to heme. The eighth cranial nerves are susceptible because they consist of CNS axons, myelin, and neuroglial tissue along their subarachnoid course. The persistence of HO-1 protein implies continuous exposure of CNS to free heme or an excessively sensitive transcriptional response of the HO-1 gene. The conversion of heme iron to hemosiderin probably involves both translational and transcriptional activation of ferritin biosynthesis. [ABSTRACT FROM AUTHOR]

Abstract: Atherogenesis is associated with inflammation and oxidative stress. Activation of renin-angiotensin system with generation of angiotensin II and type 1 receptor (AT1R) stimulation has been amply reported in atherosclerosis. Since angiotensin II type 2 receptor (AT2R) activity is purported to oppose the effects of AT1R, we hypothesized that AT2R (agtr2) over-expression would inhibit atherogenesis. We prepared recombinant adeno-associated virus type-2 (AAV) carrying AT2R cDNA (AAV/AT2R), and homozygous LDLR-deficient (KO) mice were given AAV/AT2R, AAV/Neo or saline. All mice were placed on a high cholesterol diet. After 18 weeks, AT2R was found to be over-expressed systemically in AAV/AT2R-treated mice. Atherogenesis in aorta was reduced in the AAV/AT2R group by ≈50% compared to other LDLR KO mice groups. Expression of NADPH oxidase, nitrotyrosine and NF-κB was increased in aortic tissues of the LDLR KO mice given saline or AAV/Neo, but not in mice with AT2R upregulation. Expression of endothelial nitric oxide synthase (eNOS) and heme-oxygenase-1 (HO-1) was decreased and that of the lectin-like oxidized-LDL receptor (LOX-1) increased in the LDLR KO mice, but not in the mice with AT2R over-expression. Further, Akt-1 phosphorylation was reduced in the LDLR KO mice, but not in the mice with AT2R over-expression. Thus, AT2R upregulation can reduce atherogenesis, possibly by modulating oxidative stress and the pro-inflammatory cascade, mediated via Akt-1. Over-expression of AT2R may be an important therapeutic approach in atherosclerosis. [Copyright &y& Elsevier]

Abstract: The production of adhesion molecules and subsequent attachment of leukocytes to endothelial cells (ECs) are critical early events in atherogenesis. These adhesion molecules thus play an important role in the development of this disease. Recent studies have highlighted the chemoprotective and anti-inflammatory effects of cinnamaldehyde, a Cinnamomum cassia Presl-specific diterpene. In our current study, we have examined the effects of both cinnamaldehyde and extracts of C. cassia on cytokine-induced monocyte/human endothelial cell interactions. We find that these compounds inhibit the adhesion of TNFα-induced monocytes to endothelial cells and suppress the expression of the cell adhesion molecules, VCAM-1 and ICAM-1, at the transcriptional level. Moreover, in TNFα-treated ECs, the principal downstream signal of VCAM-1 and ICAM-1, NF-κB, was also found to be abolished in a time-dependent manner. Interestingly, cinnamaldehyde exerts its anti-inflammatory effects by blocking the degradation of the inhibitory protein IκB-α, but only in short term pretreatments, whereas it does so via the induction of Nrf2-related genes, including heme-oxygenase-1 (HO-1), over long term pretreatments. Treating ECs with zinc protoporphyrin, a HO-1 inhibitor, partially blocks the anti-inflammatory effects of cinnamaldehyde. Elevated HO-1 protein levels were associated with the inhibition of TNFα-induced ICAM-1 expression. In addition to HO-1, we also found that cinnamaldehyde can upregulate Nrf2 in nuclear extracts, and can increase ARE-luciferase activity and upregulate thioredoxin reductase-1, another Nrf2-related gene. Moreover, cinnamaldehyde exposure rapidly reduces the cellular GSH levels in ECs over short term treatments but increases these levels after 9 h exposure. Hence, our present findings indicate that cinnamaldehyde suppresses TNF-induced singling pathways via two distinct mechanisms that are activated by different pretreatment periods. [Copyright &y& Elsevier]

Summary: Reactive oxygen species (ROS) are important in the initiation and promotion of cells to neoplastic growth. Heme-oxygenase (HO)-1, the inducible form of heme-oxygenase, is a cytoprotective enzyme that plays a central role in the defence against oxidative stress and is implicated in the protection of lung tissue against exogenous oxidant exposure. We investigated whether the expression of HO-1 would be decreased in lung tumour as compared with tumour-free adjacent lung tissues. HO-1 expression was quantified by immunohistochemistry in tumour macrophages, in macrophages of tumour-free lung and in tumour cells of surgical specimens collected from 53 individuals with surgically resectable non-small cell lung cancer (NSCLC). The expression of HO-1 was decreased in tumour as compared with tumour-free lung macrophages. No correlations were observed between the expression of HO-1 and both the clinicopathological characteristics and the overall survival of the examined subjects. In conclusion, our data show that macrophages of non-small cell lung cancer exhibit impaired anti-oxidant defence mechanisms, likely mediated by HO-1. Conversely, HO-1 expression does not seem to be associated with lung tumour progression and prognosis. [Copyright &y& Elsevier]

Inflammatory bowel disease is a multifactorial inflammatory disease of the colon and rectum with an unknown etiology. In the present study, we aimed to investigate whether heme oxygenase-1 (HO-1) induction by glutamine could protect colitis-induced damage from oxidative, inflammatory, and apoptotic damage. The rats were divided into four groups. Group 1 had TNBS colitis alone, group 2 had TNBS-induced colitis and glutamine 1 g/kg/day intragastric gavage for 3 days before TNBS solution administration and 15 days following TNBS solution administration, group 3 had glutamine alone 1 g/kg/day intragastric gavage for 18 days before being killed, and group 4 had isotonic saline solution alone 1 cm3/rat intragastric gavage for 18 days before being killed. Colonic malondialdehyde (MDA) levels, glutathione (GSH) levels, caspase-3 activities, and HO-1 expressions of the killed rats were measured. Nuclear factor kappa B (NF-κB) and HO-1 expression were evaluated by immunohistochemical examination of the colonic tissue. TNBS-induced colitis significantly increased the colonic MDA levels, caspase-3 activities, and HO-1 expression in comparison to the control group. Glutamine treatment was associated with increased HO-1 expression and GSH levels and decreased MDA levels and caspase-3 activity. Histopathological examination revealed that the intestinal mucosal structure was preserved in the glutamine-treated group. In addition to this, treatment with glutamine significantly increased HO-1 expression and decreased NF-κB expression by immunohistochemistry when compared to the TNBS-induced colitis group. Glutamine reduced colonic damage in TNBS-induced colitis. The mechanism of the protection associated with glutamine was due to antioxidant, antiapoptotic, anti-inflammatory, and HO-1 induction effects. [ABSTRACT FROM AUTHOR]