Role Of Heme Oxygenase-1 Research Articles

Role of heme oxygenase-1 on lipopolysaccharide-induced activation of NLRP3 inflammasomes in alveolar macrophages of rats

Objective To evaluate the role of heme oxygenase-1 (HO-1) on lipopolysaccharide (LPS)-induced activation of NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasomes in alveolar macrophages of rats. Methods NR8383 cells of rat alveolar macrophages cultured in vitro were seeded in 96-well plates at a density of 4×104 cells/ml and divided into 4 groups (n=48 each) using a random number table method: control group (group C), group LPS (group L), LPS+ HO-1 siRNA group (group L+ HO-1 siRNA), and LPS+ Con siRNA group (group L+ Con siRNA). The cells were cultured in normal culture atmosphere in group C. NR8383 cells were stimulated with 10 μg/ml LPS in L, L+ HO-1 siRNA and L+ Con siRNA groups.Cells were transfected with HO-1 siRNA at 48 h before stimulation with LPS in group L+ HO-1 siRNA and with Con siRNA at 48 h before stimulation with LPS in group L+ Con siRNA.The cells were collected and incubated for 24 h after stimulation with LPS for measurement of the cell viability, expression of HO-1 and NLRP3 mRNA (by real-time polymerase chain reaction), expression of HO-1, NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and caspase-1 (by Western blot), and concentrations of interleukin-1beta (IL-1β) and interleukin-18 (IL-18) in the supernatant (by enzyme-linked immunosorbent assay). Results Compared with group C, the cell viability was significantly decreased, the expression of HO-1 and NLRP3 protein and mRNA, ASC and caspase-1 was up-regulated, and the IL-1β and IL-18 concentrations were increased in L, L+ HO-1 siRNA and L+ Con siRNA groups (P 0.05). Conclusion HO-1 is involved in LPS-induced activation of NLRP3 inflammasomes in alveolar macrophages of rats. Key words: Heme oxygenase-1; Lipopolysaccharides; NLR family, pyrin domain-containing 3 protein

The Protective Role of Heme Oxygenase-1 (HO-1) in Chronic Subdural Hematoma

Abstract INTRODUCTION Many studies have revealed that angiogenesis and inflammation are closely linked to the pathophysiology of chronic subdural hematoma (CSDH). The development of CSDH is an inflammatory process that begins as a local inflammatory reaction of the dura meter to injury or external stimuli such as blood or CSF. This process causes neovascularization of the outer membrane of CSDH and vascular hyperpermeability. Heme oxygenase-1 (HO-1) is a key enzyme that catalyzes the degradation of heme and produces biliverdin, ferrous iron, and carbon monoxide. HO-1 expression is induced by oxidative stress, and the increasing expression seems to be protective in animal studies. We hypothesized that HO-1 has a protective impact on the severity of CSDH. METHODS This study is designed to correlate the histopathology of the outer membrane of CSDH and HO-1 level in the CSDH hematoma as an indicator of inflammatory status with the clinical presentation of patient and computed tomography (CT) radiological findings of a consecutive series of patients suffered from CSDH. This is a single-center, perspective cohort study. From 2014 to 2017, we enrolled 97 patients with CSDH, who has undergone surgical intervention (burr-hole drainage or craniotomy evacuation). We collect the clinical data, radiological information, and outer membrane and supernatant of the CSDH. We use enzyme-linked immunosorbent assay (ELISA) to measure the concentration of HO-1 in the supernatant of CSDH. RESULTS A significant negative correlation between the HO-1 and the thickness of CSDH is noted (P = .001). On increasing HO-1 by 1 ng/L, the CSDH thickness decreases by 81 mm (P < .005). CONCLUSION Our study demonstrates that HO-1, an important enzyme in angiogenesis and in the inflammation pathway, has a key impact on CSDH severity. A significant negative correlation between the HO-1 and thickness of CSDH has been proved.

The role of HO-1/BMMSCs in rat reduced-size liver transplantation

Objective To explore the effect and mechanism of heme oxygenase-1 (HO-1) gene modified bone marrow mesenchymal stem cells (BMMSCs) on rat reduced-size liver transplantation. Methods 50 male Brown Norway (BN) rats were used to prepare BMMSCs. Male Lewis and BN rats were 75, respectively. BN rats were randomly divided into model group (n=25), stem cell group (n=25) and combined group (n=25). Acute rejection models following 50% reduced-size transplantaton were established in rats using two-cuff technique, 1 ml of normal saline, BMMSCs suspension, or HO-1/BMMSCs suspension were injected immediately after surgery. Rats were executed at an instant, 3rd, 7th and 14th day after surgery to identify BMMSCs and HO-1/adenovirus infection efficiency. Evaluated hepatic pathology by HE staining. Liver function indexes were detected. Portal vein pressure on 7th day after surgery was detected. The levels of endothelin-1 (ET-1) and nitric oxide (NO) in serum were detected using ELISA. The expressions of ET-1 in liver were detected by immunohistochemistry staining and Western blotting. Results High purity BMMSCs were obtained and HO-1/BMMSCs were successfully infected. Compared with model group, liver tissue injury and rejection were alleviated in stem cell group and combined group, liver function was improved, and the combined group was superior to stem cell group. The portal vein pressure in model group, stem cell group, and combined group were 21.3±0.2 mmHg, 11.2±0.2 mmHg, and 10.1±0.1 mmHg, respectively. The portal vein pressure in three groups showed a decreasing trend, difference was statistically significant (P<0.05). On the 3rd, 7th and 14th day after surgery, compared with model group, the expression levels of ET-1 and NO in the stem cell group and the combined group were decreased, and the combined group was significantly lower than stem cell group (P<0.05). Conclusion HO-1/BMMSCs improved liver function and portal vein pressure after reduced-size liver transplantation in rats, and may play a protective role by regulating ET-1/NO expression. Key words: Heme oxygenase-1; Mesenchymal stromal cells; Liver transplantation; Rat; Portal pressure

The Role of Heme Oxygenase 1 in the Protective Effect of Caloric Restriction against Diabetic Cardiomyopathy.

Type 2 diabetes mellitus (DM2) leads to cardiomyopathy characterized by cardiomyocyte hypertrophy, followed by mitochondrial dysfunction and interstitial fibrosis, all of which are exacerbated by angiotensin II (AT). SIRT1 and its transcriptional coactivator target PGC-1α (peroxisome proliferator-activated receptor-γ coactivator), and heme oxygenase-1 (HO-1) modulates mitochondrial biogenesis and antioxidant protection. We have previously shown the beneficial effect of caloric restriction (CR) on diabetic cardiomyopathy through intracellular signaling pathways involving the SIRT1–PGC-1α axis. In the current study, we examined the role of HO-1 in diabetic cardiomyopathy in mice subjected to CR. Methods: Cardiomyopathy was induced in obese diabetic (db/db) mice by AT infusion. Mice were either fed ad libitum or subjected to CR. In an in vitro study, the reactive oxygen species (ROS) level was determined in cardiomyocytes exposed to different glucose levels (7.5–33 mM). We examined the effects of Sn(tin)-mesoporphyrin (SnMP), which is an inhibitor of HO activity, the HO-1 inducer cobalt protoporphyrin (CoPP), and the SIRT1 inhibitor (EX-527) on diabetic cardiomyopathy. Results: Diabetic mice had low levels of HO-1 and elevated levels of the oxidative marker malondialdehyde (MDA). CR attenuated left ventricular hypertrophy (LVH), increased HO-1 levels, and decreased MDA levels. SnMP abolished the protective effects of CR and caused pronounced LVH and cardiac metabolic dysfunction represented by suppressed levels of adiponectin, SIRT1, PPARγ, PGC-1α, and increased MDA. High glucose (33 mM) increased ROS in cultured cardiomyocytes, while SnMP reduced SIRT1, PGC-1α levels, and HO activity. Similarly, SIRT1 inhibition led to a reduction in PGC-1α and HO-1 levels. CoPP increased HO-1 protein levels and activity, SIRT1, and PGC-1α levels, and decreased ROS production, suggesting a positive feedback between SIRT1 and HO-1. Conclusion: These results establish a link between SIRT1, PGC-1α, and HO-1 signaling that leads to the attenuation of ROS production and diabetic cardiomyopathy. CoPP mimicked the beneficial effect of CR, while SnMP increased oxidative stress, aggravating cardiac hypertrophy. The data suggest that increasing HO-1 levels constitutes a novel therapeutic approach to protect the diabetic heart. Brief Summary: CR attenuates cardiomyopathy, and increases HO-1, SIRT activity, and PGC-1α protein levels in diabetic mice. High glucose reduces adiponectin, SIRT1, PGC1-1α, and HO-1 levels in cardiomyocytes, resulting in oxidative stress. The pharmacological activation of HO-1 activity mimics the effect of CR, while SnMP increased oxidative stress and cardiac hypertrophy. These data suggest the critical role of HO-1 in protecting the diabetic heart.

Sevoflurane has postconditioning as well as preconditioning properties against hepatic warm ischemia-reperfusion injury in rats.

Ischemia-reperfusion (IR) injury is inevitable after liver transplantation and liver resection with inflow occlusion. Sevoflurane has been widely used during hepatobiliary surgery and was reported to exhibit preconditioning (PreC) properties against hepatic IR injury; however, its postconditioning (PostC) properties remain unknown. This study examined whether a clinically applicable dose of sevoflurane has PostC and PreC properties against hepatic IR injury and roles of heme oxygenase-1 (HO-1). Warm ischemia was induced in male Wistar rats, excluding the sham group, for 1h, followed by 3h of reperfusion. Group C received propofol from 60min before ischemia until the end of the experimental procedure. In the SPreC and SPostC groups, propofol was replaced by 2.5% sevoflurane for 30min from 35min before ischemia in the SPreC group and for 30min from 5min before reperfusion in the SPostC group. The SPreC+Z and SPostC+Z groups received a HO-1 inhibitor, zinc protoporphyrin (Znpp), 60min before ischemia, and sevoflurane PreC and PostC were induced. Serum aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase levels, and histological damage scores in the SPreC and SPostC groups were significantly lower than those in group C. Inhibiting HO-1 with Znpp partially blocked these protective effects of sevoflurane. Sevoflurane PreC and PostC significantly increased the number of HO-1-positive Kupffer cells in comparison with group C, and Znpp prevented sevoflurane-induced HO-1 expression. PostC and PreC by sevoflurane at a clinically applicable dose have equally protective effects against hepatic IR injury by increasing HO-1 expression.

A novel chalcone derivative, L2H17, ameliorates lipopolysaccharide-induced acute lung injury via upregulating HO-1 activity

BackgroundChalcone, a natural product, has a wide range of biological activities. L2H17, a chalcone derivative, was synthesized and screened in our previous study and exhibited excellent anti-inflammatory property in vitro. This study investigated the therapeutic potential of L2H17 on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the role of heme oxygenase-1 (HO-1). Materials and methodsAn ALI animal model was induced by LPS (10 mg/kg) intratracheal instillation. The effect of L2H17 on LPS-induced structural damage was determined using hematoxylin and eosin (HE) staining, and tissue edema extent was examined. Bronchoalveolar lavage fluid (BALF) was harvested to assess the levels of related cytokines by enzyme-linked immunosorbent assay (ELISA), and superoxide dismutase (SOD) activity was also assessed. HO-1 expression was determined using immunohistochemistry and western blotting. The effects of L2H17 on LPS stimulation in RAW 264.7 and the involvement of the HO-1 pathway were investigated. ResultsL2H17 alleviated the histopathological manifestations and tissue edema. Moreover, L2H17 decreased the production of pro-inflammatory factors in BALF and increased SOD activity. In vitro, L2H17 significantly reduced pro-inflammatory cytokine production. Additionally, L2H17 improved the expression of HO-1 in LPS-treated lung tissue and RAW 264.7. We also found that the inhibitory effect of L2H17 on the inflammatory responses was attenuated by an inhibitor of HO-1 activity, Tin protoporphyrin IX (SnPP). ConclusionOur data confirmed that L2H17 can exert protective effect on ALI in vitro and in vivo by inhibiting inflammatory responses and modulating the HO-1 pathway.

Heme Oxygenase-1 Has an Antitumor Role in Breast Cancer.

Aims: Heme oxygenase-1 (HO-1) is an enzyme involved in cellular responses to oxidative stress and has also been shown to regulate processes related to cancer progression. In this regard, HO-1 has been shown to display a dual effect with either antitumor or protumor activity, which is also true for breast cancer (BC). In this work, we address this discrepancy regarding the role of HO-1 in BC. Results: HO-1 was detected in human BC tissues, and its protein levels correlated with reduced tumor size and longer overall survival time of patients, thus suggesting the clinical importance of HO-1 in this type of cancer. Contrariwise, nuclear localization of HO-1 correlated with higher tumor grade suggesting that the effect of HO-1 is dependent on its cellular localization. In vivo experiments showed that both pharmacological activation and genetic overexpression of HO-1 reduce the tumor burden in two different animal models of BC. Furthermore, the pharmacological and genetic activation of HO-1 in several BC cell lines reduce the cellular viability by inducing apoptosis and cell cycle arrest and decrease the cellular migration and invasion rates by modulating pathways involved in the epithelial-mesenchymal transition. Furthermore, HO-1 activation impaired in vivo the metastatic dissemination. Innovation and Conclusion: By using various BC cell lines and animal models as well as human tumor samples, we demonstrated that total HO-1 displays antitumor activities in BC. Furthermore, our study suggests that HO-1 subcellular localization may explain the differential effects observed for the protein in different tumor types.

Resveratrol protects against early cardiomyopathic changes-induced by Type-1 diabetes through a heme-oxygenase-1 dependent mechanism

Diabetes can be considered as a state of chronic inflammation and oxidative stress. Excessive oxidative stress is implicated in the pathogenesis of all diabetic complications. Heme oxygenase-1 is an antioxidant enzyme that is upregulated in response to a variety of insults as a protective mechanism. Resveratrol (RSV) is a polyphenol that exhibits promising pharmacological effects in a variety of disease models. In this study, we investigated the role of RSV in prevention of early pathological changes in the diabetic heart as well as the role of hemeoxygenase-1 in this regard. To achieve this aim, diabetes was induced by ip injection of streptozotocin (50 mg/kg). The rats were divided into 5 experimental groups; normal control (CTR), diabetic control (DM), diabetic rats treated with RSV (DM+RSV); 10 mg/kg) in drinking water, diabetic rats treated with a combination of RSV and an HO-1 inhibitor, Zinc protoporphyrin (ZnPP), (DM + RSV+ZnPP); 10 µmole/Kg/week I.P) and diabetic rats treated with ZnPP alone (DM + ZnPP). Induction of diabetes was accompanied by a significant increase in cardiac MDA level and TGF-β protein expression as well as a significant reduction in eNOS and HO-1 expression. Chronic treatment with RSV significantly attenuated the abovementioned biochemical changes associated with diabetes in addition to alleviation of diabetes-induced histopathological alterations. Furthermore, the effect of RSV was diminished when the HO-1 activity was blocked by ZnPP. These results demonstrate the role of HO-1 in mediating RSV protective effects against diabetes-induced early cardiomyopathy.

The role of heme oxygenase-1 on oxidative stress injury induced by zinc oxide nanoparticles in human umbilical vein endothelial cells line EA.hy926 cells

Objective: To explore the effect of heme oxygenase-1 (HO-1) on level of reactive oxygen species (ROS) induced by zinc oxide nanoparticles (ZnO-NPs) in Human umbilical vein endothelial cells line EA.hy926. Methods: The EA.hy926 cells in logarithmic growth phase were incubated with 0.0, 2.5, 5.0, 10.0 and 15.0 mg/L ZnO-NPs respectively. The ROS level, reflected by mean fluorescence intensity (MFI), was examined by flow cytometer after 4 hours exposure, the protein expression of HO-1 which was determined by Western Blot after exposed to ZnO-NPs for 24 hours. Cells incubated with 15.0 mg/L were set as the ZnO-NPs group; a blank control group was set at the same time. Cells were pretreated with HO-1 inhibitor zinc protoporphyrin (ZnPPIx) and HO-1 activator cobalt protoporphyrin (CoPPIx), they were classified as ZnPPIx group and CoPPIx group. 15 mg/L ZnO-NPs was chosen to conduct the experiment of HO-1 activation and inhibition. Cells were classified as ZnPPIX+ ZnO-NPs group and CoPPIx+ ZnO-NPs group after pretreated with 10 μmol/L ZnPPIx or CoPPIx for 1 h, added 15 mg/L ZnO-NPs to cell culture medium. In all groups ROS levels were detected after exposed to ZnO-NPs for 4 hours, the protein expression of HO-1 was detected after exposed to ZnO-NPs for 24 hours. Results: With the increased dose of ZnO-NPs, levels of ROS and HO-1 in EA.hy926 cells were clearly elevated (the MFI of 0.0, 2.5, 5.0, 10.0 and 15.0 mg/L ZnO-NPs incubated groups was 22 627.22±718.27, 24 726.47±568.52, 31 141.75±1 312.24, 39 824.82±4 774.74, 50 569.03±1 497.63 respectively, and HO-1 relative expression were 0.16±0.01, 0.19±0.02, 0.16±0.01, 0.23±0.02, 0.92±0.06 respectively). HO-1 expression in ZnPPIx pretreatment group decreased compared with ZnO-NPs group (1.05±0.05 vs. 1.12±0.01, P<0.05), meanwhile ROS level enhanced (62 683.95±2 589.59 vs. 53 654.53±2 229.01, P<0.05). However, CoPPIx pretreatment had higher HO-1 level and lower level of ROS compared with ZnO-NPs group (HO-1: 1.74±0.11 vs. 0.22±0.03, P<0.05; ROS: 32 845.04±993.48 vs. 53 654.53±2 229.01, P<0.05). Conclusions: Exposure to ZnO-NPs significantly induced ROS generation in EA.hy926 cells in a dose-dependent manner. HO-1 regulated ZnO-NPs-induced oxidative stress.

HO-1 is a favorable prognostic factor for HBV-HCC patients who underwent hepatectomy.

BackgroundMore than 500,000 people suffered from hepatocelluar carcinoma (HCC) annually and the relative incidence to mortality rate indicates its unfavorable prognosis. Several studies have proved that heme-oxygenase-1 (HO-1) is indirectly engaged in the invasion and the metastasis of some types of malignancies, including breast cancer, prostate cancer, and lung cancer. The role of HO-1 in hepatitis B virus (HBV)-related HCC is still not clarified.Materials and methodsThe Western blot, doubling time, cell cycle analysis, migration assay, invasion assay, gene transfection, xenograft animal model, immunohistochemistry staining, and clinical validation study were applied in this study.ResultsHO-1 overexpression not only decreased the growth but also inhibited the migration and invasion in human HBV-HCC cells (Hep-3B vs PLC/PRF/5). The inhibitory effect on growth, migration, and invasion is further demonstrated by the overexpression of HO-1 in Hep-3B cell by transfection study. Furthermore, HO-1 decreasing the growth of HBV-HCC was confirmed in animal study. The clinical validation illustrated that higher HO1 expression was also associated with favorable disease-free survival of HBV-HCC patients who underwent hepatectomy.ConclusionsWe identified HO-1 as a favorable prognostic factor for HBV-HCC patients who underwent hepatectomy.

Sorafenib and docosahexaenoic acid act in synergy to suppress cancer cell viability: a role of heme oxygenase 1

BackgroundDocosahexaenoic acid (DHA) is a long chain n-3 polyunsaturated fatty acid that has anticancer activity. Heme oxygenase 1 (HO-1) is a potential therapeutic target due to its cytoprotective activity in cancer cells. We recently reported that DHA induces HO-1 gene transcription in human cancer cells by augmenting the degradation of Bach1 protein, which functions as a negative regulator of HO-1. Since the degradation of Bach1 protein relies on protein phosphorylation, we hypothesized that DHA-induced HO-1 gene transcription could be attenuated by kinase inhibitors, resulting in an enhanced cytotoxicity. Sorafenib, a tyrosine kinase inhibitor, was first applied to test our hypothesis.MethodsHuman cancer cell lines and a xenograft nude mouse model were applied to test our hypothesis. Gene expression was analyzed by western blot analysis and reporter gene assay. Cell viability was analyzed using a colorimetric assay. Isobologram was applied to analyze drug action.ResultsPretreatment of cancer cells with Sorafenib significantly attenuated DHA-induced degradation of Bach1 protein. Consequently, DHA-induced HO-1 gene transcription was reversed by Sorafenib as evidenced by western blot and reporter gene analysis. Sorafenib acted synergistically with DHA to suppress cancer cell viability in various human cancer cell lines and suppressed tumor xenograft growth in mice fed a fish oil enriched diet (high n-3/DHA), as compared to mice fed a corn oil (high n-6) diet. Screening of the NCI-Oncology Drug Set IV identified a group of anticancer compounds, including Sorafenib, which enhanced DHA’s cytotoxicity, as well as a set of compounds that attenuated DHA’s cytotoxicity.ConclusionsWe demonstrate that sorafenib attenuates DHA-induced HO-1 expression and acts in synergy with DHA to suppress cancer cell viability and tumor growth. Considering the known health benefits of DHA and the clinical effectiveness of Sorafenib, their combination is an attractive therapeutic strategy against cancer.

Up-regulation of heme oxygenase-1 expression and inhibition of disease-associated features by cannabidiol in vascular smooth muscle cells.

Aberrant proliferation and migration of vascular smooth muscle cells (VSMC) have been closely linked to the development and progression of cardiovascular and cancer diseases. The cytoprotective enzyme heme oxygenase-1 (HO-1) has been shown to mediate anti-proliferative and anti-migratory effects in VSMC. This study investigates the effect of cannabidiol (CBD), a non-psychoactive cannabinoid, on HO-1 expression and disease-associated functions of human umbilical artery smooth muscle cells (HUASMC). HO-1 protein and mRNA were significantly increased by CBD in a time- and concentration-dependent manner. Although the expression of several cannabinoid-activated receptors (CB1, CB2, G protein-coupled receptor 55, transient receptor potential vanilloid 1) was verified in HUASMC, CBD was shown to induce HO-1 via none of these targets. Instead, the CBD-mediated increase in HO-1 protein was reversed by the glutathione precursor N-acetylcysteine, indicating the participation of reactive oxygen species (ROS) signaling; this was confirmed by flow cytometry-based ROS detection. CBD-induced HO-1 expression was accompanied by inhibition of growth factor-mediated proliferation and migration of HUASMC. However, neither inhibition of HO-1 activity nor knockdown of HO-1 protein attenuated CBD-mediated anti-proliferative and anti-migratory effects. Indeed, inhibition or depletion of HO-1 resulted in induction of apoptosis and intensified CBD-mediated effects on proliferation and migration. Collectively, this work provides the first indication of CBD-mediated enhancement of HO-1 in VSMC and potential protective effects against aberrant VSMC proliferation and migration. On the other hand, our data argue against a role of HO-1 in CBD-mediated inhibition of proliferation and migration while substantiating its anti-apoptotic role in oxidative stress-mediated cell fate.

Role of heme oxygenase-1 and its reaction product, carbon monoxide, in manifestation of breast cancer stem cell-like properties: Notch-1 as a putative target

Cancer stem cells (CSCs) constitute a subpopulation of transformed cells that possess intrinsic ability to undergo selfrenewal and differentiation, which drive tumour resistance and cancer recurrence. It has been reported that CSCs possess enhanced protection against oxidative stress induced by reactive oxygen species compared with nonstem-like cancer cells. In the present work, we investigated the role of heme oxygenase-1 (HO-1), a representative antioxidant enzyme, on the stemness and selfrenewal of human breast CSCs. We found that pharmacologic or genetic inhibition of HO-1 attenuated the sphere formation, whereas HO-1 inducers enhanced the number and the size of tumourspheres in breast CSCs. Carbon monoxide (CO) is endogenously generated as a consequence of degradation of heme by HO-1. The proportion of populations of CD44+/CD24− cells retaining CSC properties was increased in MDA-MB-231 cells treated with a CO-releasing molecule (CORM-2). Following CORM-2 treatment, the expression of Notch-1 and related genes Jagged-1 and Hes1 was increased, which was accompanied by the mammosphere formation. Taken together, these findings suggest that HO-1-derived CO production stimulates the formation of mammospheres in breast cancer cells through activation of Notch-1 signalling.

Regulatory Role of Heme Oxygenase and Nitric Oxide Synthase in Macrophages

Regulatory Role of Heme Oxygenase and Nitric Oxide Synthase in Macrophages

Research Progress in Understanding the Relationship Between Heme Oxygenase-1 and Intracerebral Hemorrhage.

Intracerebral hemorrhage (ICH) is a fatal acute cerebrovascular disease, with a high morbidity and mortality. Following ICH, erythrocytes release heme and several of its metabolites, thereby contributing to brain edema and secondary brain damage. Heme oxygenase is the initial and rate-limiting enzyme of heme catabolism, and the expression of heme oxygenase-1 (HO-1) is rapidly induced following acute brain injury. As HO-1 exerts it effects via various metabolites, its role during ICH remains complex. Therefore, in-depth studies regarding the role of HO-1 in secondary brain damage following ICH may provide a theoretical basis for neuroprotective function after ICH. The present review aims to summarize recent key studies regarding the effects of HO-1 following ICH, as well as its influence on ICH prognosis.

Abstract A019: Heme-oxygenase 1 drives the metabolic fate in prostate cancer

Abstract Prostate cancer (PCa) is the second leading cause of cancer-associated death in men. Energetic metabolism alterations have become a new hallmark of cancer, since variations in a single gene can orchestrate changes in metabolic pathways and confer an adaptive advantage. Heme-oxygenase 1 (HO-1) exerts an antitumoral role in PCa inhibiting cell proliferation, migration, tumor growth, and angiogenesis. The aim of this work was to assess the role of HO-1 in the metabolic signature of PCa. Through RNA-Seq we found a set of metabolic genes deregulated under pharmacologic induction (hemin treatment) or genetic induction of HO-1 in PC3 cells. STAR and ATP5L2 were upregulated, while HMGCS2, PRODH, and ACOT12 were downregulated. These genes encode for steroid hormone metabolism, ATP synthesis, ketogenesis, proline and lipid metabolism. The analysis of the deregulated genes (2-fold) by Gene Ontology revealed alterations in several metabolic pathways such as steroid, proline and lipid metabolism, and ATP synthesis. Functional analysis highlighted a decrease in oxygen consumption rate and ATP production under hemin treatment. Furthermore, HO-1 induction led to a decrease in the extracellular lactate levels. Bone is the only site of PCa progression, and bone cells are able to produce factors that favor progression. However, the molecular nature of this interaction remains elusive. Our results performed on cocultures of PC3 cells (treated or not with hemin) with Raw264.7 (preosteoclastic) or MC3T3 (preosteoblastic) cells demonstrate that HO-1 directs the metabolic fate of bone precursor cells due to the deregulation of glycolytic genes. HO-1 induction in PC3 cells downregulated PKM2 and LDHA expression in cocultured Raw264.7 and MC3T3 cells (p&amp;lt; 0.05). Based on our results, we propose HO-1 as a key regulator of the metabolic status of PCa cells and a powerful mediator capable of redefining the metabolic signature of bone precursor cells, thus favoring the establishment of a less aggressive phenotype. Citation Format: Valeria G. Antico Arciuch, Florencia Cascardo, Florencia Velazquez, Sofia Lage Vickers, Nicolas Anselmino, Estefania Labanca, Javier Cotignola, Geraldine Gueron, Nora Navone, Elba Vazquez. Heme-oxygenase 1 drives the metabolic fate in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A019.

Heme Oxygenase 1 in the Nervous System: Does It Favor Neuronal Cell Survival or Induce Neurodegeneration?

Heme oxygenase 1 (HO-1) up-regulation is recognized as a pivotal mechanism of cell adaptation to stress. Under control of different transcription factors but with a prominent role played by Nrf2, HO-1 induction is crucial also in nervous system response to damage. However, several lines of evidence have highlighted that HO-1 expression is associated to neuronal damage and neurodegeneration especially in Alzheimer’s and Parkinson’s diseases. In this review, we summarize the current literature regarding the role of HO-1 in nervous system pointing out different molecular mechanisms possibly responsible for HO-1 up-regulation in nervous system homeostasis and neurodegeneration.

P4221A key role for heme oxygenase-1 in anti-HLA antibody triggered monocyte adhesion and transmigration

P4221A key role for heme oxygenase-1 in anti-HLA antibody triggered monocyte adhesion and transmigration

Regulatory role of heme oxygenase-1 in silica-induced lung injury

BackgroundSilicosis, a progressive inflammatory lung disease attributed mainly to occupational exposure to silica dust, shows loss of lung function even after cessation of exposure. In addition to conventional evaluation methods such as chest X-ray, computed tomography, and spirometry, we identified heme oxygenase (HO)-1, an inducible antioxidant, as a potential biomarker to identify at-risk patients. We found that HO-1 was critical in attenuating the disease progression of silicosis; however, the key signaling pathway has not yet been elucidated. Here, we report the critical pathway after silica exposure, focusing on the role of silica-derived reactive oxygen species (ROS) signaling and its attenuation, which is mediated by HO-1 induction, in vivo and in vitro.MethodsNormal bronchial epithelial cells and a macrophage cell line, as well as a murine silicosis model generated by intratracheal administration of 2.5 mg of crystalline silica, were used in this study. The pathways activated in response to silica exposure, including the mitogen-activated protein kinase (MAPK) signaling pathway, were examined and compared with or without super-induction of HO-1.ResultsThe murine silicosis model was first assessed for the evaluation of activated pathways after silica exposure, focusing on ROS-MAPK activation. In the murine model, increased expression of HO-1 in the lungs was observed after silica-instillation. Moreover, silica-medicated activation of extracellular signal-regulated kinase (ERK) in the lungs was attenuated in response to silica-induced HO-1 upregulation. Activation of other MAPKs, such as p38 and c-Jun N-terminal kinase pathways, after silica exposure was not significantly different irrespective of HO-1 induction. Further in vitro studies showed that 1) silica-induced HO-1 was significantly attenuated by inhibiting ERK activation, and 2) carbon monoxide and bilirubin as final byproducts of HO-1 could inhibit ERK activation. Taken together, silica-induced HO-1 upregulation was mediated by ERK activation, and HO-1 further regulates ERK activation via its final byproducts, carbon monoxide and bilirubin.ConclusionsThis is the first study to demonstrate the regulatory role of HO-1 in silicosis. This finding could contribute to the development of a treatment strategy of monitoring HO-1 levels as a marker of therapeutic intervention.

Various roles of heme oxygenase-1 in response of bone marrow macrophages to RANKL and in the early stage of osteoclastogenesis

Heme oxygenase-1 (HO-1; encoded by Hmox1), a downstream target of the Nrf2 transcription factor, has been postulated to be a negative regulator of osteoclasts (OCLs) differentiation. Here, we further explored such a hypothesis by examining HO-1 effects in different stages of osteoclastogenesis. We confirmed the inhibition of the expression of OCLs markers by Nrf2. In contrast, both the lack of the active Hmox1 gene or HO-1 silencing in OCLs precursor cells, bone marrow macrophages (BMMs), decreased their differentiation towards OCLs, as indicated by the analysis of OCLs markers such as TRAP. However, no effect of HO-1 deficiency was observed when HO-1 expression was silenced in BMMs or RAW264.7 macrophage cell line pre-stimulated with RANKL (considered as early-stage OCLs). Moreover, cobalt protoporphyrin IX (CoPPIX) or hemin, the known HO-1 inducers, inhibited OCLs markers both in RANKL-stimulated RAW264.7 cells and BMMs. Strikingly, a similar effect occurred in HO-1−/− cells, indicating HO-1-independent activity of CoPPIX and hemin. Interestingly, plasma of HO-1−/− mice contained higher TRAP levels, which suggests an increased number of bone-resorbing OCLs in the absence of HO-1 in vivo. In conclusion, our data indicate that HO-1 is involved in the response of bone marrow macrophages to RANKL and the induction of OCLs markers, but it is dispensable in early-stage OCLs. However, in vivo HO-1 appears to inhibit OCLs formation.