Protective Effect Of Heme Oxygenase-1 Research Articles

Elevation of HO-1 expression protects the intestinal mucosal barrier in severe acute pancreatitis via inhibition of the MLCK/p-MLC signaling pathway

In severe acute pancreatitis (SAP), intestinal mucosal barrier damage can cause intestinal bacterial translocation and induce or aggravate systemic infections. Heme oxygenase-1 (HO-1) is a validated antioxidant and cytoprotective agent. This research aimed to investigate the effect and mechanism of HO-1 on SAP-induced intestinal barrier damage in SAP rats. Healthy adult male Sprague-Dawley rats were randomly separated into the sham-operated group, SAP group, SAP + Hemin group, and SAP + Znpp group. The rat model of SAP was established by retrograde injection of sodium taurocholate (5%) into the biliopancreatic duct. Hemin (a potent HO-1 activator) and Znpp (a competitive inhibitor of HO-1) were injected intraperitoneally in the selected groups 24 h before SAP. Serum and intestinal tissue samples were collected for analysis after 24 h in each group. Hemin pretreatment significantly reduced systemic inflammation, intestinal oxidative stress, and intestinal epithelial apoptosis in SAP by increasing HO-1 expression. Meanwhile, pretreatment with Hemin abolished the inhibitory effect on the expression of the tight junction proteins and significantly inhibited the activation of the MLCK/P-MLC signaling pathway. Conversely, ZnPP completely reversed these effects. Our study indicates that upregulation of HO-1 expression attenuates the intestinal mucosal barrier damage in SAP. The protective effect of HO-1 on the intestine is attributed to MLCK/p-MLC signaling pathway inhibition.

Intestinal Microbiota Participates in the Protective Effect of HO-1/BMMSCs on Liver Transplantation With Steatotic Liver Grafts in Rats.

The present study aimed to explore whether heme oxygenase-1 (HO-1)-modified bone marrow mesenchymal stem cells (BMMSCs) have a protective effect on liver transplantation with steatotic liver grafts in rats, and to determine the role of the intestinal microbiota in such protection. HO-1/BMMSCs were obtained by transduction of Hmox1 gene [encoding heme oxygenase (HO-1)]-encoding adenoviruses into primary rat BMMSCs. Steatotic livers were obtained by feeding rats a high-fat diet, and a model of liver transplantation with steatotic liver grafts was established. The recipients were treated with BMMSCs, HO-1/BMMSCs, or neither, via the portal vein. Two time points were used: postoperative day 1 (POD 1) and POD 7. The results showed that under the effect of HO-1/BMMSCs, the degree of steatosis in the liver grafts was significantly reduced, and the level of liver enzymes and the levels of pro-inflammatory cytokines in plasma were reduced. The effect of HO-1/BMMSCs was better than that of pure BMMSCs in the prolongation of the rats' postoperative time. In addition, HO-1/BMMSCs promoted the recovery of recipients' intestinal structure and function, especially on POD 7. The intestinal villi returned to normal, the expression of tight junction proteins was restored, and intestinal permeability was reduced on POD 7. The intestinal bacterial of the LT group showed significantly weakened energy metabolism and overgrowth. On POD 1, the abundance of Akkermansiaceae was higher. On POD 7, the abundance of Clostridiaceae increased, the level of lipopolysaccharide increased, the intestinal mucosal barrier function was destroyed, and the levels of several invasive bacteria increased. When treated with HO-1/BMMSCs, the energy metabolism of intestinal bacteria was enhanced, and on POD 1, levels bacteria that protect the intestinal mucosa, such as Desulfovibrionaceae, increased significantly. On POD 7, the changed intestinal microbiota improved lipid metabolism and increased the levels of butyrate-producing bacteria, such as Lachnospiraceae. In conclusion, HO-1/BMMSCs have protective effects on steatotic liver grafts and the intestinal barrier function of the recipients. By improving lipid metabolism and increasing the abundance of butyrate-producing bacteria, the changed intestinal microbiota has a protective effect and prolongs the recipients' survival time.

Heme Oxygenase-1 Protects Hair Cells From Gentamicin-Induced Death

Gentamicin ototoxicity can generate free radicals within the inner ear, leading to permanent damage to sensory hair cells (HCs) and eventually hearing loss. The following study examined the alterations of oxidative damage-related genes in the cochlea and important molecules responsible for oxidation following gentamicin injury in vitro. The RT2 Profiler polymerase chain reaction (PCR) array was used to screen candidate targets for treatment to prevent hearing loss caused by gentamicin. We found that during gentamicin-induced death in HCs, Heme oxygenase-1 (HO-1) had a high fold change in the HCs of the cochlea. Moreover, the use of CoPPIX to induce HO-1 inhibited gentamicin-induced HC death, while HO-1 inhibitors ZnPPIX after CoPPIX reversed this process. Furthermore, the inhibitors of NF-E2-related factor-2 (Nrf2) reduced the expression of HO-1 and inhibited the protective effect of HO-1 after gentamicin, thus suggesting that the Nrf2/HO-1 axis might regulate gentamicin-associated ototoxicity. We further demonstrated that induction of HO-1 up-regulated the expression of Nrf2 in both cochlear and HEI-OC1 cells. In summary, these findings indicated that HO-1 protects HCs from gentamicin by up-regulating its expression in HCs and interacting with Nrf2 to inhibit reactive oxygen species (ROS).

The Protective Effect of Heme Oxygenase-1 on Liver Injury Caused by DON-Induced Oxidative Stress and Cytotoxicity

Deoxynivalenol (DON) is a kind of Fusarium toxin that can cause a variety of toxic effects. Oxidative stress and DNA damage play a critical role in the toxicity of DON. However, previous studies focused more on acute toxicity in vivo/vitro models and lacked subchronic toxicity study in vivo. The potentially harmful effect of DON given at doses comparable to the daily human consumption in target organs, especially the liver, which is the main detoxification organ of DON, is also still not fully understood. Otherwise, Heme Oxygenase-1 (HO-1) has also reduced cell damage under the DON condition according to our previous study. Therefore, we used a rodent model that mimicked daily human exposure to DON and further explored its mechanism of toxic effects on liver tissue and Hepa 1–6 cell line. We also used adeno-associated virus (AAV)-modified HO-1 expressing by tail vein injection and constructed lentivirus-Hepa 1–6 cell line for mimicking HO-1 protective ability under the DON condition. The main results showed that both 30 d and 90 d exposures of DON could cause low-grade inflammatory infiltration around hepatic centrilobular veins. The reactive oxygen species (ROS) and 8-hydroxy-2 deoxyguanosine (8-OHdG) increased during DON exposure, indicating oxidation stress and DNA damage. Significantly, AAV-mediated liver-specific overexpression of HO-1 reduced DON-induced liver damage and indirectly protected the abilities of antioxidant enzyme/DNA damage repair system, while AAV-mediated silence of HO-1 produced the opposite effect. In addition, we found that overexpression of HO-1 could enhance autophagy and combined it with an antioxidant enzyme/DNA damage repair system to inhibit DON-induced hepatocyte damage. Altogether, these data suggest that HO-1 reduces the oxidative stress and DNA damage caused by DON sub-chronic exposure through maintaining DNA repair, antioxidant activity, as well as autophagy.

Protective effects of upregulated HO-1 gene against the apoptosis of human retinal pigment epithelial cells in vitro.

To investigate the protective effect of heme oxygenase-1 (HO-1) against H2O2-induced apoptosis in human ARPE-19 cells. The lentiviral vector expressing HO-1 was prepared and transfected into apoptotic ARPE-19 cells induced by H2O2. Functional experiments including cell counting kit-8 (CCK-8) assay, flow cytometry (FCM) and mitochondrial membrane potential assay were conducted. The ultrastructure of ARPE-19 cells was observed using transmission electron microscope (TEM). It was found that exogenous HO-1 significantly ameliorated H2O2-induced loss of cell viability, apoptosis and intracellular levels of reactive oxygen species (ROS) in ARPE-19 cells. The overexpression of HO-1 facilitated the transfer of nuclear factor erythroid-2-related factor 2 (Nrf2) from cytoplasm to nucleus, which in turn upregualted expressions HO-1 and B-cell lymphoma-2 (Bcl-2). Furthermore, HO-1 upregulation further inhibited H2O2-induced release of cysteinyl aspartate specific proteinase-3 (caspase-3). Exogenous HO-1 protect ARPE-19 cells against H2O2-induced oxidative stress by regulating the expressions of Nrf2, HO-1, Bcl-2, and caspase-3.

Heme Oxygenase-1-Mediated Autophagy Protects against Oxidative Damage in Rat Nucleus Pulposus-Derived Mesenchymal Stem Cells.

Although endogenous nucleus pulposus-derived mesenchymal stem cell- (NPMSC-) based regenerative medicine has provided promising repair strategy for intervertebral disc (IVD) degeneration, the hostile microenvironments in IVD, including oxidative stress, can negatively affect the survival and function of the NPMSCs and severely hinder the endogenous repair process. Therefore, it is of great importance to reveal the mechanisms of the endogenous repair failure caused by the adverse microenvironments in IVD. The aim of this study was to investigate the effect of oxidative stress on the rat NPMSCs and its underlying mechanism. Our results demonstrated that oxidative stress inhibited cell viability, induced apoptosis, and increased the production of reactive oxygen species (ROS) in NPMSCs. In addition, the results showed that the expression level of heme oxygenase-1 (HO-1) increased at an early stage but decreased at a late stage when NPMSCs were exposed to oxidative stress, and the oxidative damages of NPMSCs could be partially reversed by promoting the expression of HO-1. Further mechanistic analysis indicated that the protective effect of HO-1 against oxidative damage in NPMSCs was mediated by the activation of autophagy. Taken together, our study revealed that oxidative stress could inhibit cell viability, induce apoptosis, and increase ROS production in NPMSCs, and HO-1-mediated autophagy might act as a protective response to the oxidative damage. These findings might enhance our understanding on the mechanism of the endogenous repair failure during IVD degeneration and provide novel research direction for the endogenous repair of IVD degeneration.

Protective effects of heme oxygenase-1-transduced bone marrow-derived mesenchymal stem cells on reduced-size liver transplantation: Role of autophagy regulated by the ERK/mTOR signaling pathway

Autophagy is a critical lysosomal pathway that degrades cytoplasmic components to maintain cell homeostasis and provide substrates for energy metabolism. A study revealed that heme oxygenase-1 (HO-1)-transduced bone marrow-derived mesenchymal stem cells (BM-MSCs) could protect 50% reduced-size liver transplantation (RSLT) in a rat model. However, the mechanisms remain mostly unknown. The aim of the present study was to explore the effects and related mechanism of autophagy on the protection conferred by HO-1-transduced BM-MSCs (HO-1/BM-MSCs) on 50% RSLT in a rat model. The authors established an acute rejection model following 50% RSLT in rats, with recipients divided into three groups receiving treatment with BM-MSCs, HO-1/BM-MSCs or normal saline (NS) injected through the dorsal penile vein. Transplanted liver tissues at 0, 1, 3, 5, 7, 10 and 14 days following transplantation were acquired for further analysis. The results indicated that the expression of autophagy-related proteins LC3 and Beclin-1 increased, the levels of ERK and p-ERK increased, and the levels of mammalian target of rapamycin (mTOR) and p-mTOR decreased in the HO-1/BM-MSCs. These observations indicated that autophagy is involved in the protective effects of HO-1/BM-MSCs on liver grafts following RSLT, possibly via upregulation of autophagy-related proteins through the ERK/mTOR signaling pathway.

Protective effects of heme oxygenase-1 against severe acute pancreatitis via inhibition of tumor necrosis factor-\u03b1 and augmentation of interleukin-10

BackgroundHeme oxygenase-1 (HO-1) is an inducible defense gene which plays a significant role in inflammation. HO-1 protects cells and tissues through the mechanism of anti-oxidation, maintaining microcirculation and anti-inflammation. The aim of the current study is to investigate the role of HO-1 on systemic inflammatory response in severe acute pancreatitis (SAP).MethodsForty male Sprague-Dawley (SD) rats were randomly assigned into four groups: control group (n = 10); SAP group (n = 10), SAP model was induced by retrograde injection of 3% sodium taurocholate through pancreatic duct; HO-1 stimulation group (n = 10), SD rats were injected 75 μg/kg hemin intraperitoneally 30 min after induction of SAP; HO-1 inhibition group (n = 10), SD rats were injected 20 μg/kg Zinc porphyrin (Zn-PP) intraperitoneally 30 min after induction of SAP. After 24 h of SAP establishment, tissues were collected for HO-1, tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) mRNA expression, and blood samples were collected for cytokines and biochemical measurements. Meanwhile, the histopathological changes of pancreas and liver tissues were observed.ResultsThe expression of HO-1 mRNA and protein were significantly induced by SAP in rat pancreas and liver. Hemin treatment significantly decreased oxidative stress and TNF-α in plasma and tissues, while the IL-10 was significantly increased. Pancreas and liver injury induced by SAP was markedly attenuated by Hemin treatment. Moreover, inhibition of HO-1 expression by Zn-PP administration aggravated the injury caused by SAP.ConclusionsInduction of HO-1 in early SAP may modulate systemic inflammatory response and prevent pancreas and nearby organs such as liver injury through inhibition of TNF-α and augmentation of IL-10.

Effect of nuclear factor-E2-related factor 2 signal pathway on the heme oxygenase-1 against ethanol-induced osteoblast damage

Objective To find the mechanism of the heme oxygenase-1 (HO-1) against ethanol-induced osteoblast damage, and clarify the effect of nuclear factor-E2-related factor 2 (Nrf-2)/antioxidant response element (ARE) signal pathway on the protective effect of HO-1, to provide theoretical support for the later research and the clinical application of biological agent of HO-1. Methods The osteoblast cells were isolated and cultured, then HO-1 was transfected using Lipofectamine 2000. After cells were exposed to ethanol for 24 h, the levels of Nrf-2 and HO-1 were measured by Western blotting. The enzyme activity of myeloperoxidase (MPO) and glutathione peroxidase (GSH-Px) were tested using the corresponding kits. Results The enzyme activity of MPO and GSH-Px was respectively (54.17±20.61) mU/mg prot and (7.94±2.42) U/mg prot in the positive group, which was significantly decreased (P=0.023, 0.012) as compared with that in the negative group. The enzyme activity of MPO and GSH-Px was significantly increased to (286.54±13.82) mU/mg prot and (38.59±5.30) U/mg prot (P=0.000, 0.000) in HO-1 group as compared with that in the negative group and positive group. The Nrf-2 and HO-1 levels (respectively 0.27±0.08 and 0.81±0.05) were significantly decreased than those in the positive group (respectively 0.62±0.11 and 1.26±0.20, P=0.016, 0.003), but Nrf-2 and HO-1 were all significantly increased in the HO-1 group(respectively 0.94±0.10, 2.43±0.13; P=0.000, 0.000). Conclusion The protective effect of HO-1 against ethanol-induced osteoblast damage was related to Nrf-2/ARE signal pathway, which could activate and enhance the celluar antioxidant ability to reduce the damage of the osteoblast cells induced by alcohol. Key words: Heme oxygenase-1; Osteoblast; Nuclear factor-E2-related factor 2; Myeloperoxidase; Glutathione peroxidase

The Protective Effect of Heme Oxygenase-1 against Intestinal Barrier Dysfunction in Cholestatic Liver Injury Is Associated with NF-\u03baB Inhibition

Heme oxygenase-1 (HO-1) is reported to protect against liver injury, but little Is known about its effect on the intestinal barrier in cholestatic liver injury. In this study, we investigated the effects of HO-1 and its enzymatic by-product on intestinal barrier dysfunction in bile duct ligation (BDL) rats and explored the possible mechanism. The HO-1 inducer cobalt protoporphyrin (CoPP) and carbon monoxide-releasing molecule-2 (CORM-2) were used; the expression levels of tight junction (TJ) proteins, intestinal inflammation and NF-κB p65 were measured. For an in vitro experiment, stable Caco-2 cell lines were constructed, one overexpressed the HO-1 gene and another with that gene knocked down, and the specific NF-κB inhibitor JSH-23 was used. CoPP and CORM-2 treatment alleviated liver and intestinal mucosa injury in BDL rats; improved ZO-1, claudin-1 and PCNA expression; and reduced cell apoptosis and intestinal interleukin-6 (IL-6) expression. In vitro studies confirmed that HO-1, ZO-1 and occludin were overex-pressed in HO-1-transfected Caco-2 cells, while decreased in the short hairpin HO (sh-HO-1) group. JSH-23 significantly increased occludin expression in both the HO-1 overexpression and sh-HO-1 groups, compared with their respective controls. HO-1 overexpression also inhibited the nuclear translocation of NF-κB p65 after lipopolysaccharide (LPS) treatment. Additionally, phospho-p65 expression in sh-HO-1 cells was significantly increased compared with that of the HO-1 overexpression group. In conclusion, HO-1 and CORM-2 improved intestinal epithelial barrier function in BDL-induced cholestatic liver injury mainly by restoring TJ, reducing cell apoptosis and intestinal inflammation. HO-1 exerts a protective effect, which is partially correlated with the regulation of NF-κB.

Ferritin heavy chain mediates the protective effect of heme oxygenase-1 against oxidative stress

The phenomenon that heme oxygenase-1 (HO-1) protects cell from injury yet its enzymatic product, iron, may facilitate generation of free radical has been long puzzling. Here we establish a functional connection between ferritin heavy chain (FHC) and HO-1. In human lupus nephritis HO-1 and FHC are colocalized within the glomeruli. In rodent anti-Thy1 (thymocyte antigen 1) induced glomerulonephritis, heme oxygenase blockade lowers the expression of FHC and accelerates mesangial cell death. Stimulation of heme oxygenase in cultured rat mesangial cell enhances its resistance to hydrogen peroxide, whereas FHC knockdown by RNA interference compromises this salutary effect. RNA interference of HO-1 makes the cell more susceptible to hydrogen peroxide, which can be rescued by forced expression of wild-type FHC but not mutants that lose the capacity of iron storage and ferroxidase activity. Phosphorylation of JunD was not sustained in these cells. Microarray analysis identifies four candidate transcriptional factors that may regulate the HO-1-induced transcription of FHC. Our results support the role of FHC in neutralizing the iron toxicity as well as mediating the protective effect of HO-1 in response to oxidative stress.

Protective effect of heme oxygenase-1 on Wistar rats with heart failure through the inhibition of inflammation and amelioration of intestinal microcirculation.

BackgroundMyocardial infarction (MI) has likely contributed to the increased prevalence of heart failure (HF). As a result of reduced cardiac function, splanchnic blood flow decreases, causing ischemia in villi and damage to the intestinal barrier. The induction of heme oxygenase-1 (HO-1) could prevent, or lessen the effects of stress and inflammation. Thus, the effect and mechanism thereof of HO-1 on the intestines of rats with HF was investigated.MethodsMale Wistar rats with heart failure through ligation of the left coronary artery were identified with an left ventricular ejection fraction of < 45% through echocardiography and then divided into various experimental groups based on the type of peritoneal injection they received [MI: saline; MI + Cobalt protoporphyrin (CoPP): CoPP solution; and MI + Tin mesoporphyrin IX dichloride (SnMP): SnMP solution]. The control group was comprised of rats without coronary ligation. Echocardiography was performed before ligation for a baseline and eight weeks after ligation in order to evaluate the cardiac function of the rats. The bacterial translocation (BT) incidence, mesenteric microcirculation, amount of endotoxins in the vein serum, ileum levels of HO-1, carbon oxide (CO), nitric oxide (NO), interleukin (IL)-10, tumour necrosis factor-α (TNF-α), and the ileum morphology were determined eight weeks after the operation.ResultsThe rats receiving MI + CoPP injections exhibited a recovery in cardiac function, an amelioration of mesenteric microcirculation and change in morphology, a lower BT incidence, a reduction in serum and ileac NO and TNF-α levels, and an elevation in ileac HO-1, CO, and interleukin-10 (IL-10) levels compared to the MI group (P < 0.05). The rats that received the MI + SnMP injections exhibited results inverse to the MI (P < 0.05) group.ConclusionsHO-1 exerted a protective effect on the intestines of rats with HF by inhibiting the inflammation and amelioration of microcirculation through the CO pathway. This protective effect could be independent from the recovery of cardiac function.

The role of heme oxygenase-1 in the protection of chronic intermittent hypoxia-induced lung injury in vivo

To investigate the effect of chronic intermittent hypoxia (CIH) on inflammatory and pathological changes of the lung in an animal model as well as the protective effect of heme oxygenase-1 in this process. Twenty-four Male Sprague-Dawley rats were randomly divided into 4 groups: intermittent normoxia (IN) group, CIH group, IN+hemin injection (hemin) group and CIH+hemin injection (CIH+hemin) group. The CIH profiling was repetitive 4 min 10% O₂and 2 min 21% O₂for 8 hours per day for 6 weeks. Animals exposed to IN were kept in an identical chamber receiving intermittent air at the same flow rate. Hemin was intraperitoneally injected (4 mg/kg) to induced HO-1 expression, and other 2 groups only received an injection of same amount of saline. Western blot was utilized to detect the pulmonary HO-1 expression levels and ELISA was used to examine the pulmonary cytokine levels. H&E staining was used to investigate pathological changes of the lung. CIH significantly induced HO-1 expression in the lung and hemin induced a synergistic increase of HO-1 expression. CIH exposure significantly increased pulmonary inflammatory cytokines levels, TNF-α [(2.20 ± 0.10) vs (1.80 ± 0.08) ng/ml], IL-6 [(0.87 ± 0.05) vs (0.52 ± 0.05) ng/ml], CINC-1 [(66 ± 6) vs (39 ± 5) pg/ml] and MCP-1 [(2.20 ± 0.09) vs (1.40 ± 0.10) ng/ml], accelerated cell apoptosis and induced pathological changes of the lung, while hemin could inhibit the elevation of cytokines [(TNF-α:(1.60 ± 0.20) ng/ml, IL-6: (0.60 ± 0.07) ng/ml, CINC-1: (45 ± 6) pg/ml, MCP-1: (1.80 ± 0.10) ng/ml, all P<0.05] and cell apoptosis, as well as reversing the structural injury of the lung under CIH condition. CIH leads to inflammatory stress, cell apoptosis and pathological changes within the lung, while HO-1 could inhibit inflammation and apoptosis, thereby reversing the pulmonary injury.

Protective effect of heme oxygenase-1 on intestinal epithelial barrier function of Caco-2 cells under hypoxia

Objective To investigate the regulator effect of heme oxygenase-1 (HO-1) on intestinal epithelial barrier function under hypoxia.Methods Eukaryotic overexpression vector pShuttle-CMVHO-1 was transfected into Caco-2 cells.The cells were divided into four groups:normoxia group,hypoxia group,transfection group,and negative control group.The mRNA and protein expression of HO-1 and Occludin was detected by using reverse transcription-polymerase chain reaction(RT-PCR) and Western blotting.Immunofluorescence was used to analyze Occludin.Results The expression levels of Occludin mRNA and protein were lower in hypoxia group than in normoxia group (0.43 ± 0.03 vs.1.0,P ＜ 0.01 ;0.62 ±0.07 vs.1.0,P ＜0.01).As compared with hypoxia group,the expression of Occludin mRNA and protein was significantly increased in transfection group (0.65 ±0.04 vs.0.43 ±0.03,P ＜0.05 ; 0.89 ± 0.06 vs.0.62 ±0.07,P ＜0.05).But there were no significant differences in the expression of Occludin mRNA and protein between the hypoxia group and negative control group (0.43 ± 0.03 vs.0.40 ± 0.05,P ＞0.05 ; 0.62 ±0.07 vs.0.61 ±0.04,P ＞0.05).Immunofluorescence staining showed that Occludin in linear fluorescence was distributed around the cell membrane in normoxia group,the immunofluorescence staining was disrupted in both hypoxia group and negative control group,and the immunofluorescence staining was not disrupted so seriously in transfection group.Conclusion HO-1 ameliorates intestinal epithelial dysfunction through up-regulating the expression of Occludin mRNA and protein under hypoxia. Key words: Heme oxygenase-1 ; Gene transfection; Tight junction; Intestinal mucosal barrier

Heme oxygenase-1 alleviates vascular complications associated with metabolic syndrome: Effect on endothelial dependent relaxation and NO production

Protective effect of Heme oxygenase-1 (HO-1) induction from hypertension was previously reported in a diabetic animal model. Here, the effect of HO-1 induction on vascular complications associated with metabolic syndrome (MetS) was investigated.MetS was induced in rats by fructose drinking for 12weeks while HO-1 was induced by hemin or curcumin administration in the last 6weeks. Then, aortic HO-1 protein expression was assessed, blood pressure (BP) was recorded and serum levels of glucose and insulin were measured. Concentration response curves for phenylephrine (PE), KCl, and acetylcholine (ACh) were obtained in thoracic aortic cross sections. Aortic reactive oxygen species (ROS) and nitric oxide (NO) generation were also studied.Both hemin and curcumin significantly inhibited the elevated systolic and diastolic BP seen in MetS animals. While not affected by MetS, HO-1 expression was significantly increased by hemin and curcumin treatment. HO-1 induction did not affect the exaggerated vasoconstriction response to KCl and PE. However, HO-1 induction prevented the impaired relaxation and NO generation in aorta isolated from MetS animals. In addition, the HO inhibitor, tin protoporphyrin, abolished the hemin protective effect on relaxation and NO generation. HO-1 induction prevented the elevated hyperinsulinemia associated with MetS. Furthermore, HO-1 induction inhibited ROS production in aorta isolated from MetS animals.In conclusion, Heme oxygenase-1 alleviates vascular complications associated in MetS through maintaining endothelial-dependent relaxation and NO generation in addition to improving insulin sensitivity.

Heme oxygenase-1 expression protects the heart from acute injury caused by inducible Cre recombinase

The protective effect of heme oxygenase-1 (HO-1) expression in cardiovascular disease has been previously demonstrated using transgenic animal models in which HO-1 is constitutively overexpressed in the heart. However, the temporal requirements for protection by HO-1 induction relative to injury have not been investigated, but are essential to employ HO-1 as a therapeutic strategy in human cardiovascular disease states. Therefore, we generated mice with cardiac-specific, tamoxifen (TAM)-inducible overexpression of a human HO-1 (hHO-1) transgene (myosin heavy chain (MHC)-HO-1 mice) by breeding mice with cardiac-specific expression of a TAM-inducible Cre recombinase (MHC-Cre mice), with mice containing an hHO-1 transgene preceded by a floxed-stop signal. MHC-HO-1 mice overexpress HO-1 mRNA and the enzymatically active protein following TAM administration (40 mg/kg body weight on 2 consecutive days). In MHC-Cre controls, TAM administration leads to severe, acute cardiac toxicity, cardiomyocyte necrosis, and 80% mortality by day 3. This cardiac toxicity is accompanied by a significant increase in inflammatory cells in the heart that are predominantly neutrophils. In MHC-HO-1 mice, HO-1 overexpression ameliorates the depression of cardiac function and high mortality rate observed in MHC-Cre mice following TAM administration and attenuates cardiomyocyte necrosis and neutrophil infiltration. These results highlight that HO-1 induction is sufficient to prevent the depression of cardiac function observed in mice with TAM-inducible Cre recombinase expression by protecting the heart from necrosis and neutrophil infiltration. These findings are important because MHC-Cre mice are widely used in cardiovascular research despite the limitations imposed by Cre-induced cardiac toxicity, and also because inflammation is an important pathological component of many human cardiovascular diseases.

Nuclear Translocation of Heme Oxygenase-1 Confers Resistance to Imatinib in Chronic Myeloid Leukemia Cells

Identification of imatinib mesylate as a potent inhibitor of the Abl kinase and the subsequent findings that this compound displays growth inhibitory and pro-apoptotic effects in Bcr-Abl+ cells, has deeply conditioned CML treatment. Unfortunately the initial striking efficacy of this drug has been overshadowed by the development of clinical resistance. A wide variety of molecular mechanisms can underlie such resistance mechanisms. In the recent years, heme oxygenase-1 (HO-1) expression has been reported as an important protective endogenous mechanism against physical, chemical and biological stress and this cytoprotective role has already been demonstrated for several solid tumors and acute leukemias. The aim of the present study was to investigate the effect of HO-1 expression on cell proliferation and apoptosis in chronic myeloid leukemia cells, K562 and LAMA-84 cell lines following imatinib treatment. Cells were incubated for 24h with Imatinib (1 μM) alone or in combination with Hemin (10μM), an inducer of HO-1. In addition, cells were also treated with HO byproducts, bilirubin and carbon monoxide (CO), or with a protease inhibitor (Ed64) to inhibit HO-1 nuclear translocation. Pharmacological induction of HO-1 was able to overcome the effect of imatinib. The cytoprotective effect of HO-1 was further confirmed after silencing HO-1 by siRNA. Interestingly, neither bilirubin nor CO was able to protect cells from Imatinib-induced toxicity. By contrast, the protective effect of HO-1 was mitigated by the addition of E64d, preventing HO-1 nuclear translocation. Finally, imatinib was able to increase the formation of cellular reactive oxygen species (ROS) and this effect was reversed by HO-1 induction or the addition of N-acetylcisteine (NAC). In conclusion, the protective effect of HO-1 on imatinib-induced cytotoxicity does not involve its enzymatic byproducts, but rather the nuclear translocation of HO-1 following proteolytic cleavage.

Isoflurane Preconditioning at Clinically Relevant Doses Induce Protective Effects of Heme Oxygenase-1 on Hepatic Ischemia Reperfusion in Rats

BackgroundActivation of heme oxygenase-1 (HO-1) has been proved to reduce damages to the liver in ischemia reperfusion injury. The objective of present study was to determine whether clinic relevant doses of isoflurane treatment could be sufficient to activate HO-1 inducing, which confers protective effect against hepatic ischemia-reperfusion injury.MethodsThe hepatic artery and portal vein to the left and the median liver lobes of forty male Sprague-Dawley rats were occluded for 60 minutes. Reperfusion was allowed for 4 hours before the animal subjects were sacrificed. Six groups (n = 12) were included in the study. A negative control group received sham operation and positive control group a standard ischemia-reperfusion regimen. The third group was pretreated with isoflurane prior to the ischemia-reperfusion. The fourth group received an HO-1 inhibitor zinc protoporphyrin (Znpp) prior to the isoflurane pretreatment and the ischemia-reperfusion. The fifth group received Znpp alone before ischemia-reperfusion procedure, and the sixth group was administrated with a HO-1 inducer hemin prior to IR. HO-1 in the liver was measured using an enzymatic activity assay, a Western blot analysis, as well as immunohistochemical method. Extent of liver damage was estimated by determination of the serum transaminases, liver lipid peroxidation and hepatic histology. Infiltration of the liver by neutrophils was measured using a myeloperoxidase activity assay. TNFα mRNA in the liver was measured using RT-PCR.ResultsIsoflurane pretreatment significantly attenuated the hepatic injuries and inflammatory responses caused by the ischemia reperfusion. Selectively inhibiting HO-1 with ZnPP completed blocked the protective effects of isoflurane. Inducing HO-1 with hemin alone produced protective effects similar in magnitude to that of isoflurane.ConclusionsClinic relevant doses of isoflurane attenuate ischemia reperfusion injury in rats by increasing the HO-1 expression and activity.

Protective Effect of Heme Oxygenase-1 on High Glucose-Induced Pancreatic β-Cell Injury

BackgroundGlucose toxicity that is caused by chronic exposure to a high glucose concentration leads to islet dysfunction and induces apoptosis in pancreatic β-cells. Heme oxygenase-1 (HO-1) has been identified as an anti-apoptotic and cytoprotective gene. The purpose of this study is to investigate whether HO-1 up-regulation when using metalloprotophyrin (cobalt protoporphyrin, CoPP) could protect pancreatic β-cells from high glucose-induced apoptosis.MethodsReverse transcription-polymerase chain reaction was performed to analyze the CoPP-induced mRNA expression of HO-1. Cell viability of INS-1 cells cultured in the presence of CoPP was examined by acridine orange/propidium iodide staining. The generation of intracellular reactive oxygen species (ROS) was measured using flow cytometry. Glucose stimulated insulin secretion (GSIS) was determined following incubation with CoPP in different glucose concentrations.ResultsCoPP increased HO-1 mRNA expression in both a dose- and time-dependent manner. Overexpression of HO-1 inhibited caspase-3, and the number of dead cells in the presence of CoPP was significantly decreased when exposed to high glucose conditions (HG). CoPP also decreased the generation of intracellular ROS by 50% during 72 hours of culture with HG. However, decreased GSIS was not recovered even in the presence of CoPP.ConclusionOur data suggest that CoPP-induced HO-1 up-regulation results in protection from high glucose-induced apoptosis in INS-1 cells; however, glucose stimulated insulin secretion is not restored.

Effects of heme oxygenase-1 mediated by cell penetrating peptide PEP-1 on myocardial ischemia/reperfusion injury in isolated rat hearts

Objective To investigate the protective effects of heme oxygenase-1 （HO-1） mediated by cell penetrating peptide PEP-1 on myocardium against ischemia/reperfusion （IR） injury in isolated rat hearts. Methods Healthy male SD rats weighing 220-280 g were anesthetized with intraperitoneal pentobarbital. Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95%O2-5% CO2 at 37 ℃. Eighteen isolated rat hearts were randomly divided into 3 groups （ n = 6 each）： Ⅰ group sham operation （group S）;Ⅱ group IR and Ⅲ group PEP-1/HO-1 ＋ IR （group HO-1）. The isolated rat hearts were perfused with an oxygena-ted （95% O2-5% CO2 ） K-H solution at 37 ℃ in a Langendorff apparatus and were subjected to 40 min of global ischemia followed by 50 min of reperfusion after 30 min of stabilization. In group Ⅲ （group HO- 1 ） the isolated hearts were perfused with 50 μmol/L PEP-1/HO-1 for 15 min before ischemia. After 50 min of reperfusion, HO-1expression, MDA content and SOD activity in myocardial tissues were determined. The activities of creatine kinase （CK） and lactic dehydrogenase （LDH） in coronary effluent fluid were measured. Results The HO- 1 expression was significanfly higher in HO-1 group than in group IR. IR induced significant increase in MDA content and decrease in SOD activity in myocardium and CK and LDH activities in coronary effluent in group Ⅱ compared with group S. PEP-1/HO-1 significantly attenuated IR-induced changes. Conciusion HO-1 mediated by PEP-1 has protective effects on myocardium ngainst IR injury in rats. Key words: Heme oxygenase（decyclizing）; Cell penetrating peptides; Myocardial reperfusion injury