Heme Oxygenase-1 mRNA Levels Research Articles

Overexpression of Heme Oxygenase-1 Prevents Renal Interstitial Inflammation and Fibrosis Induced by Unilateral Ureter Obstruction.

Renal fibrosis plays an important role in the onset and progression of chronic kidney diseases. Many studies have demonstrated that heme oxygenase-1 (HO-1) is involved in diverse biological processes as a cytoprotective molecule, including anti-inflammatory, anti-oxidant, anti-apoptotic, antiproliferative, and immunomodulatory effects. However, the mechanisms of HO-1 prevention in renal interstitial fibrosis remain unknown. In this study, HO-1 transgenic (TG) mice were employed to investigate the effect of HO-1 on renal fibrosis using a unilateral ureter obstruction (UUO) model and to explore the potential mechanisms. We found that HO-1 was adaptively upregulated in kidneys of both TG and wild type (WT) mice after UUO. The levels of HO-1 mRNA and protein were increased in TG mice compared with WT mice under normal conditions. HO-1 expression was further enhanced after UUO and remained high during the entire experimental process. Renal interstitial fibrosis in the TG group was significantly attenuated compared with that in the WT group after UUO. Moreover, overexpression of HO-1 inhibited the loss of peritubular capillaries. In addition, UUO-induced activation and proliferation of myofibroblasts were suppressed by HO-1 overexpression. Furthermore, HO-1 restrained tubulointerstitial infiltration of macrophages and regulated the secretion of inflammatory cytokines in UUO mice. We also found that high expression of HO-1 inhibited reactivation of Wnt/β-catenin signaling, which could play a crucial role in attenuating renal fibrosis. In conclusion, these data suggest that HO-1 prevents renal tubulointerstitial fibrosis possibly by regulating the inflammatory response and Wnt/β-catenin signaling. This study provides evidence that augmentation of HO-1 levels may be a therapeutic strategy against renal interstitial fibrosis.

Cross-talk between two antioxidants, thioredoxin reductase and heme oxygenase-1, and therapeutic implications for multiple myeloma

Multiple myeloma (MM) is characterized by an accumulation of abnormal clonal plasma cells in the bone marrow. Despite recent advancements in anti-myeloma therapies, MM remains an incurable disease. Antioxidant molecules are upregulated in many cancers, correlating with tumor proliferation, survival, and chemoresistance and therefore, have been suggested as potential therapeutic targets. This study investigated the cross-talk between two antioxidant molecules, thioredoxin reductase (TrxR) and heme oxygenase-1 (HO-1), and their therapeutic implications in MM. We found that although auranofin, a TrxR inhibitor, significantly inhibited TrxR activity by more than 50% at lower concentrations, myeloma cell proliferation was only inhibited at higher concentrations of auranofin. Inhibition of TrxR using lower auranofin concentrations induced HO-1 protein expression in myeloma cells. Using a sub-lethal concentration of auranofin to inhibit TrxR activity in conjunction with HO-1 inhibition significantly decreased myeloma cell growth and induced apoptosis. TrxR was shown to regulate HO-1 via the Nrf2 signaling pathway in a ROS-dependent manner. Increased HO-1 mRNA levels were observed in bortezomib-resistant myeloma cells compared to parent cells and HO-1 inhibition restored the sensitivity to bortezomib in bortezomib-resistant myeloma cells. These findings indicate that concurrent inhibition of HO-1 with either a TrxR inhibitor or with bortezomib would improve therapeutic outcomes in MM patients. Hence, our findings further support the need to target multiple antioxidant systems alone or in combination with other therapeutics to improve therapeutic outcomes in MM patients.

Effects of hyperbaric oxygen therapy on acetaminophen induced nephrotoxicity and hepatotoxicity: the role of heme oxygenase-1

The aim of this study was to investigate the effects of hyperbaric oxygen (HBO) therapy on acetaminophen (APAP) induced renal and liver injudr and the role of heme oxygenase-1 (HO-1) activation. Wistar-Albino rats were randomly assigned into four groups. Control group received no treatment. APAP (3gr/kg) was administered by gastric lavage in APAP group. Animals in the APAP+HBO and APAP+zinc protoporphyrin (ZnPP)+HBO groups received HBO therapy (90 min at 2.5 atm), starting 1 hour after APAP administration, for 2 consecutive days.HO-1 activity was inhibited by ZnPP. APAP+ZnPP+HBO group received intraperitoneal 50 µmol\kg ZnPP injection 30 minutes after APAP treatment and HBO therapy for 2 days. Serum and tissue samples were taken at 48 hours after APAP treatment. Renal and liver functions were evaluated by serum levels of urea, creatinine and transaminases. Lipid peroxidation and tissue levels of antioxidant enzymes were measure by ELISA. Tissue injury was evaluated by light microscopy.HO-1 level was determined by immunohistochemistry. HO-1 mRNA level was investigated by polymerase chain reaction (PCR). Serum transaminase levels significantly increased after APAP treatment (p

Identification of Heme Oxygenase-1 as a Novel Predictor of Hematopoietic Stem Cell Transplantation Outcomes in Acute Leukemia

Objective: The main aim of this study was to determine the correlation between clinical outcome and heme oxygenase-1 (HO-1) expression before and after hematopoietic stem cell transplantation (HSCT) in acute leukemia. Methods: HO-1 mRNA levels in 83 patients were measured using qRT-PCR. In a comparative analysis of HO-1 levels in relation to different post-transplant outcomes, the HO-1 threshold, determined via the receiver operating characteristic (ROC) curve, was effectively used to predict clinical relapse and acute graft-versus-host disease (aGVHD). The correlations among clinical relapse, aGVHD and HO-1 expression were analyzed based on this threshold. Results: Leukemia risk stratification and relative expression of HO-1 before pretreatment had significant effects on clinical relapse. Leukemia risk stratification, relative expression of HO-1 after HSCT and the interval from diagnosis to transplantation had a significant influence on aGVHD. Both relapse and aGVHD appeared to be associated with relative HO-1 expression. The relative expression rate of HO-1 was 1.131-1.186 before pretreatment, and strongly associated with post-transplantation relapse. The relative expression rate of HO-1 was 1.102-1.144 after transplantation, and closely related to aGVHD. ROC curve analysis revealed high specificity and sensitivity of HO-1 expression in predicting relapse and aGVHD after allo-HSCT. Conclusions: HO-1 expression can be effectively used as a predictor of relapse as well as a diagnostic factor of aGVHD after transplantation for allo-HSCT patients with acute leukemia.

Liver expression of Nrf2-related genes in different liver diseases

The KEAP1-Nrf2 antioxidant signaling pathway is important in protecting liver from various insults. However, little is known about the expression of Nrf2-related genes in human liver in different diseases. This study utilized normal donor liver tissues (n=35), samples from patients with hepatocellular carcinoma (HCC, n=24), HBV-related cirrhosis (n=27), alcoholic cirrhosis (n=5) and end-stage liver disease (n=13). All of the liver tissues were from the Oriental Liver Transplant Center, Beijing, China. The expressions of Nrf2 and Nrf2-related genes, including its negative regulator Kelch-like ECH-associated protein 1 (KEAP1), its targeted gene NAD(P)H-quinone oxidoreductase 1 (NQO1), glutamate-cysteine ligase catalytic subunit (GCLC) and modified subunit (GCLM), heme oxygenase 1 (HO-1) and peroxiredoxin-1 (PRDX1) were evaluated. The expression of Nrf2 was decreased in HCC, increased in alcoholic cirrhosis and end-stage liver disease. The expression of KEAP1 was increased in all of the liver samples. The most notable finding was the increased expression of NQO1 in HCC (18-fold), alcoholic cirrhosis (6-fold), end-stage liver disease (5-fold) and HBV-related cirrhosis (3-fold). Peri-HCC also had 4-fold higher NQO1 mRNA as compared to the normal livers. GCLC mRNA levels were lower only in HCC, as compared to the normal livers and peri-HCC tissues. GCLM mRNA levels were higher in HBV-related cirrhosis and end-stage liver disease. HO-1 mRNA levels were increased in all liver tissues except for HCC. Peri-HCC had higher PRDX1 mRNA levels compared with HCC and normal livers. Nrf2 and Nrf2-related genes are aberrantly expressed in the liver in different diseases and the increase of NQO1 was the most notable finding, especially in HCC.

Heme Oxygenase-1 Is Not Decreased in Preeclamptic Placenta and Does Not Negatively Regulate Placental Soluble fms-Like Tyrosine Kinase-1 or Soluble Endoglin Secretion.

Elevated placental release of the antiangiogenic factors, soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sENG), is central to the pathophysiology of preeclampsia. It is widely accepted that heme oxygenase-1 (HO-1) is decreased in preeclamptic placenta and negatively regulates sFlt-1 and sENG production. We set out to verify these contentions. There was no difference in HO-1 mRNA or protein levels in preterm preeclamptic placentas (n=17) compared with gestationally matched controls (n=27). In silico analysis of microarray studies did not identify decreased placental HO-1 expression in preeclamptic placenta. Silencing HO-1 in primary trophoblasts did not affect sFlt-1 protein secretion after 24 or 48 hours. Silencing nuclear factor (erythroid-derived 2)-like 2 (transcription factor that upregulates HO-1) in trophoblasts also did not affect sFlt-1 secretion. Administering tin protoporphyrin IX dichloride (HO-1 inhibitor) or cobalt protoporphyrin (HO-1 inducer) into placental explants did not affect sFlt-1 or sENG secretion. Silencing HO-1 in 2 types of primary endothelial cells (human umbilical vein endothelial and uterine microvascular endothelial cells) significantly increased sFlt-1 secretion but not sENG secretion. However, HO-1 silencing selectively increased mRNA expression of sFlt-1 i13 (generically expressed sFlt-1 variant) but not of sFlt-1 e15a (sFlt-1 variant mainly expressed in placenta). Furthermore, adding tin protoporphyrin IX dichloride decreased sFlt-1, whereas adding HO-1 inducers (cobalt protoporphyrin, dimethyl fumarate, and rosiglitazone) either had no effect or increased sFlt-1 or sENG secretion (these trends are opposite to what is expected). We conclude that HO-1 expression is not decreased in preeclamptic placenta and HO-1 does not negatively regulate placental sFlt-1 and sENG secretion in placental or endothelial cells.

Biliary tract external drainage increases the expression levels of heme oxygenase-1 in rat livers.

BackgroundHeme oxygenase-1 (HO-1) protects cells by anti-oxidation, maintaining normal microcirculation and anti-inflammatory under stress. This study investigated the effects of biliary tract external drainage (BTED) on the expression levels of HO-1 in rat livers.MethodsBiliary tract external drainage was performed by inserting a cannula into the bile duct. Sixty Sprague–Dawley rats were randomized to the following groups: sham 1 h group; BTED 1 h group; bile duct ligation (BDL) 1 h group; sham 6 h group and BTED 6 h group. The expression levels of HO-1 mRNA were analyzed using real-time RT-PCR. The expression levels of HO-1 were analyzed using immunohistochemistry.ResultsThe expression levels of HO-1 mRNA in the liver of the BTED group increased significantly compared with the sham group 1 and 6 h after surgery (p < 0.05).The expression levels of HO-1 in the BTED group increased significantly compared with the sham group 1 and 6 h after surgery. The expression levels of HO-1 mRNA in the liver in the BDL group decreased significantly compared with the sham group 1 h after surgery (p < 0.05).The expression levels of HO-1 in the BDL group decreased significantly compared with the sham group at this time.ConclusionBiliary tract external drainages increase the expression levels of HO-1 in the liver.

Effect of heat stress-induced production of mitochondrial reactive oxygen species on NADPH oxidase and heme oxygenase-1 mRNA levels in avian muscle cells

Heat stress is a major factor inducing oxidative disturbance in cells. In the present study, we investigated the mechanism of overproduction of reactive oxygen species (ROS) in cultured avian muscle cells in response to heat stress, and also focused attention on the interaction of mitochondrial superoxide anions with altered NADPH oxidase (NOX), superoxide dismutase (SOD) and heme oxygenase-1 (HO-1) mRNA levels in heat-stressed cells. Exposure of cells to heat stress conditions (41°C, 6h) resulted in increased mitochondrial superoxide and intracellular ROS levels, and increased carbonyl protein content as compared with that of normal cells (37°C). The mitochondrial uncoupler 2,4-dinitrophenol lowered intracellular ROS levels in heat-stressed cells. Heat stress increased NOX4 mRNA and decreased HO-1 mRNA levels, while SOD1 and SOD2 mRNA levels remained relatively stable in heat-stressed cells. Addition of the superoxide scavenger 4-hydroxy TEMPO to the culture medium of heat-stressed cells restored mitochondrial superoxide and intracellular ROS levels as well as NOX4 and HO-1 mRNA levels to near-normal values. We suggest that mitochondrial superoxide production could play an influential role in augmenting oxidative damage to avian muscle cells, possibly via the up-regulation of NOX4 and down-regulation of HO-1 in heat-stressed avian muscle cells.

Role of Hydroxytyrosol-dependent Regulation of HO-1 Expression in Promoting Wound Healing of Vascular Endothelial Cells via Nrf2 De Novo Synthesis and Stabilization.

Hydroxytyrosol (HT), an olive plant (Olea europaea L.) polyphenol, has proven atheroprotective effects. We previously demonstrated that heme oxygenase-1 (HO-1) is involved in the HT dependent prevention of dysfunction induced by oxidative stress in vascular endothelial cells (VECs). Here, we further investigated the signaling pathway of HT-dependent HO-1 expression in VECs. HT dose- and time-dependently increased HO-1 mRNA and protein levels through the PI3K/Akt and ERK1/2 pathways. Cycloheximide and actinomycin D inhibited both increases, suggesting that HT-triggered HO-1 induction is transcriptionally regulated and that de novo protein synthesis is necessary for this HT effect. HT stimulated nuclear accumulation of nuclear factor E2-related factor 2 (Nrf2). This Nrf2 accumulation was blocked by actinomycin D and cycloheximide whereas HT in combination with the 26S proteasome inhibitor MG132 enhanced the accumulation. HT also extended the half-life of Nrf2 proteins by decelerating its turnover. Moreover, HO-1 inhibitor, ZnppIX and CO scavenger, hemoglobin impaired HT-dependent wound healing while CORM-2, a CO generator, accelerated wound closure. Together, these data demonstrate that HT upregulates HO-1 expression by stimulating the nuclear accumulation and stabilization of Nrf2, leading to the wound repair of VECs crucial in the prevention of atherosclerosis.

Combination therapy with human umbilical cord mesenchymal stem cells and angiotensin-converting enzyme 2 is superior for the treatment of acute lung ischemia-reperfusion injury in rats.

Acute lung ischemia-reperfusion injury (ALIRI) is a serious disease that seriously affects human's life. In this study, we aimed to explore a more effective treatment method by combining human umbilical cord mesenchymal stem cells (HUMSCs) and angiotensin-converting enzyme 2 (ACE2) for ALIRI. Fifty rats were firstly divided into five groups, namely sham surgery group (sham) and four model groups (model, ACE2, HUMSCs and HUMSCs + ACE2) that were reperfused with 0.1 ml physiological saline (PS), 0.1 ml PS containing 1 × 10(6) lentiviral-ACE2/HUMSCs/ACE2 + UMSCs, respectively. Quantitative reverse transcription-PCR (qRT-PCR) and western blot assays were then conducted to detect the messenger RNA (mRNA) and protein levels of inflammatory cytokines [intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), tumour necrosis factor α (TNF-α), nuclear factor κB (NF-κB), platelet-derived growth factor (PDGF) and angiotensin II (Ang II)], antioxidant proteins [NAD(P)H quinone oxidoreductase 1 (NQO1), heme oxygenase 1 (HO-1)], DNA damage and apoptotic indicators [BCL2-associated X (Bax), cleaved caspase-3 (C-Csp 3), cleaved-poly(ADP-ribose) polymerase (C-PARP), Y-H2AX], anti-apoptotic indicator (Bcl-2) and smooth muscle cell proliferation indicator [connexin 43 (Cx43)]. According to the qRT-PCR and western results, the mRNA and protein expression levels of ICAM-1, VCAM-1, TNF-α, NF-κB, PDGF, Bax, C-Csp 3, C-PARP and Y-H2AX were significantly higher in model group than those in sham group and they were significantly reduced by HUMSCs or ACE2 treatment (P < 0.05). On the contrary, Bcl-2 showed an opposite expression trend with the previous proteins. The mRNA and protein levels of NQO1 and HO-1 were sequentially increased in sham, model, ACE2, HUMSCs and HUMSCs + ACE2 groups. Besides, HUMSCs combined with ACE2 exhibited a better inhibition effect on ALIRI than HUMSCs or ACE2 alone (P < 0.05). In summary, HUMSCs combined with ACE2 was demonstrated to have the best therapeutic effect on ALIRI through anti-inflammation, oxidative stress and anti-apoptotic processes.

Myrosinase-treated glucoerucin is a potent inducer of the Nrf2 target gene heme oxygenase 1 — studies in cultured HT-29 cells and mice

In this study, the effect of myrosinase-treated glucoerucin (GER+MYR), which releases the isothiocyanate (ITC) erucin, on heme oxygenase 1 (HO-1) gene expression and Nrf2 signaling was investigated in vitro in cultured cells and in vivo in mice. Treatment of HT-29 cells with GER+MYR resulted in a significant increase in the mRNA and protein levels of nuclear Nrf2 and HO-1. GER+MYR was more potent at enhancing the nuclear Nrf2 levels than were the following myrosinase-treated glucosinolates: sinigrin, glucoraphanin and gluconasturtiin, which are the precursors of allyl-ITC, R-sulforaphane and 2-phenylethyl ITC, respectively. GER+MYR also significantly induced HO-1 gene expression in the mouse intestinal mucosae and liver but not in the brain. Mechanistic studies suggest that GER+MYR induces Nrf2 via ERK1/2-, p38- and JNK-dependent signal transduction pathways. The GER+MYR-mediated increase in HO-1 expression is primarily attributable to p38 signaling.

Perilla frutescens modulates CYP1A1/2 and HO-1 and activates Nrf2 in oxidative stress-induced hepatotoxicity

We speculated that lipid peroxidation induced by tert-butyl hydroperoxide (t-BHP) in liver is closely linked with the metabolism mediated by CYPs. In this study, we have examined the effect of Perilla leaf extract (PLE) on CYPs using 7-ethoxyresorufin-O-deethylase (EROD, indicator of CYP1A1), 7-methoxyresorufin-O-demethylase (MROD, indicator of CYP1A2), erythromycin N-demethylase (ERDM, indicator of CYP3A), and p-nitrophenol hydroxylase (PNPH, indicator of CYP2E1) in rat liver. Rats orally pretreated with PLE (250, 500, and 1,000 mg/kg b.w.) for 5 days were administered with a single i.p. dose of t-BHP (0.5 mmol/kg). Kinetic analysis of CYP1A1/2 activities in t-BHP-treated liver demonstrated that PLE inhibits the enzyme activities by competitive and noncompetitive inhibitions. The pretreatment with PLE decreased the expression of CYP1A1/2 mRNA and protein compared with t-BHP treatment alone. A Phase II enzyme, heme oxygenase-1 (HO-1), is involved in hepatoprotection against oxidative damage, and we confirmed that PLE increases the levels of HO-1 mRNA and protein, as well as its activity in t-BHP-induced liver damage. PLE administration resulted in enhanced nuclear translocation and ARE binding of NF-E2-related factor 2. These findings suggest that PLE protects against t-BHP-induced hepatotoxicity through modulated activity and expression of selective CYPs, and ARE-driven induction of HO-1 expression and its activity.

Downregulation of HO-1 promoted apoptosis induced by decitabine via increasing p15INK4B promoter demethylation in myelodysplastic syndrome.

Decitabine, which reverses hypermethylation of the p15(INK4B) gene in vitro, has been used to relieve cytopenias and blast excess in over 50% of patients with high-risk myelodysplastic syndrome (MDS). In this study, heme oxygenase-1 (HO-1) was overexpressed in MDS cell line SKM-1, which was closely related to resistance to decitabine-induced apoptosis. We aimed to further investigate the role of HO-1 in apoptosis induced by low-dose decitabine in SKM-1 cells. Upregulation of HO-1 by transfecting it into SKM-1 cells with lentivirus vector promoted cell proliferation and protected them against apoptosis. In contrast, downregulation of HO-1 enhanced decitabine-induced apoptosis but reduced accumulation of the S phase in cell cycle. To explore the mechanism, the expressions of cell cycle-related proteins were detected after the cells were treated by decitabine in each group. p15(INK4B) and CDK4 were overexpressed in SKM-1 cells in which HO-1 was inhibited, and the expression-depending apoptosis was related to the caspase-3 pathway. Even though HO-1 was silenced, the apoptotic rate never increased as the caspase-3 pathway was blocked. It is well known that p15(INK4B) dominantly regulates the S phase of the cell cycle. p15(INK4B) was herein demethylated more evidently in the group of SKM-1 cells in which HO-1 was downregulated, as well as in the mononuclear cells of patients suffering from MDS. In the case of poor prognosis, the mRNA level of HO-1 was raised. In conclusion, overexpression of HO-1 indicated resistance to demethylation of p15(INK4B) induced by decitabine.

MicroRNA miR-24-3p promotes porcine reproductive and respiratory syndrome virus replication through suppression of heme oxygenase-1 expression.

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important viruses affecting the swine industry worldwide. Our previous research showed that PRRSV downregulates the expression of heme oxygenase-1 (HO-1), a pivotal cytoprotective enzyme, postinfection and that overexpression of HO-1 inhibits PRRSV replication. MicroRNAs regulate gene expression at the posttranscriptional level and have recently been demonstrated to play vital roles in pathogen-host interactions. The present study sought to determine whether microRNAs modulate HO-1 expression and, by doing so, regulate PRRSV replication. Using bioinformatic prediction and experimental verification, we demonstrate that HO-1 expression is regulated by miR-24-3p. A direct interaction between miR-24-3p and HO-1 mRNA was confirmed using a number of approaches. Overexpression of miR-24-3p significantly decreased HO-1 mRNA and protein levels. PRRSV infection induced miR-24-3p expression to facilitate viral replication. The suppressive effect of HO-1 induction by protoporphyrin IX cobalt chloride (CoPP; a classical inducer of HO-1 expression) on PRRSV replication in MARC-145 cells and primary porcine alveolar macrophages could also be reversed by overexpression of miR-24-3p. Collectively, these results suggested that miR-24-3p promotes PRRSV replication through suppression of HO-1 expression, which not only provides new insights into virus-host interactions during PRRSV infection but also suggests potential new antiviral strategies against PRRSV infection. MicroRNAs (miRNAs) play vital roles in viral infections by regulating the expression of viral or host genes at the posttranscriptional level. Heme oxygenase-1 (HO-1), a pivotal cytoprotective enzyme, has antiviral activity for a number of viruses, such as Ebola virus, hepatitis C virus, human immunodeficiency virus, and our focus, PRRSV, which causes great economic losses each year in the swine industry worldwide. Here, we show that PRRSV infection induces host miRNA miR-24-3p expression and that miR-24-3p regulates HO-1 expression through both mRNA degradation and translation repression. Suppression of HO-1 expression by miR-24-3p facilitates PRRSV replication. This work lends credibility to the hypothesis that an arterivirus can manipulate cellular miRNAs to enhance virus replication by regulating antiviral responses following viral infection. Therefore, our findings provide new insights into the pathogenesis of PRRSV.

Cobalt protoporphyrin protects the liver against apoptosis in rats of brain death

Brain death (BD) leads to a marked increase in apoptosis, which influences the viability of donor organs. Induction of heme oxygenase 1 (HO-1) has been shown to exert beneficial effects in different liver injury models. Therefore, we examined the effect of pretreating rats with cobalt protoporphyrin (CoPP), an HO-1 inducer, on apoptosis in liver during BD and elucidated the mechanisms involved. First, rats were killed at 0, 1, 2, 4 and 6 h after BD induction to examine the expression of hepatic HO-1. Second, rats were randomly divided into four groups (n=6): (S group) rats undergoing sham operation, (CS group) rats pretreated with CoPP for 24 h before the sham operation, (B group) rats undergoing BD for 6 h, (CB group) rats pretreated with CoPP for 24 h before BD induction. The expression levels of hepatic HO-1 mRNA and protein in rats increased at 0, 1, 2, 4 and 6h after BD induction, compared with sham operated rats. In the CB group compared with the B group, the increased hepatic expression of HO-1 correlated with a significant decrease in serum ALT/AST levels, fewer apoptotic cells in liver, increased hepatic expression of Mcl-1 and Bcl-2, and decreased hepatic expression of Bax, cytosolic cytochrome c and cleaved caspase-3. CoPP inhibits apoptosis in liver of BD rats in part via modulating the mitochondrial apoptosis pathway. HO-1 may serve as a potential target for improving the quality of organs from BD donors.

Effect of dehydroepiandrosterone treatment on hormone levels and antioxidant parameters in aged rats.

The aim of the current study was to evaluate the effect of chronic dehydroepiandrosterone (DHEA) administration on steroid hormones and antioxidant parameters in aged rats. To this end, three groups of Sprague-Dawley rats were compared: young (3 months of age) untreated; aged (19 months old) untreated; and aged rats treated with 20 mg/kg DHEA for 8 weeks. Major organs of aged rats in the untreated group demonstrated physiological atrophy, compared to those of young rats; this effect appeared to have been partially reversed by DHEA treatment. Testosterone and estradiol contents were significantly decreased and aldosterone significantly increased in aged untreated, compared to young untreated rats. Steroid hormone levels were obviously reversed, however, in aged rats treated with DHEA. Additionally, superoxide dismutase activity in serum, brain, heart, and liver was decreased, and maleic dialdehyde content in heart was markedly increased in untreated aged, compared to young, rats. Importantly, these changes in brain and heart of aged rats were reversed by DHEA treatment. Heme oxygenase mRNA levels were increased and inducible nitric oxide synthase mRNA levels decreased in aged, compared to young, rats; DHEA treatment appeared to reverse these changes. These results indicate that chronic DHEA administration may have effects on steroid hormone levels and antioxidant parameters in aged rats and result in postponement of the aging process.

Heatstroke Effect on Brain Heme Oxygenase-1 in Rats.

Exposure to high environmental temperature leading to increased core body temperature above 40°C and central nervous system abnormalities such as convulsions, delirium, or coma is defined as heat stroke. Studies in humans and animals indicate that the heat shock responses of the host contribute to multiple organ injury and death during heat stroke. Heme oxygenase-1 (HO-1)—a stress-responsive enzyme that catabolizes heme into iron, carbon monoxide, and biliverdin—has an important role in the neuroprotective mechanism against ischemic stroke. Here, we investigated the role of endogenous HO-1 in heat-induced brain damage in rats. RT-PCR results revealed that levels of HO-1 mRNA peaked at 0 h after heat exposure and immunoblot analysis revealed that the maximal protein expression occurred at 1 h post-heat exposure. Subsequently, we detected the HO-1 expression in the cortical brain cells and revealed the neuronal cell morphology. In conclusion, HO-1 is a potent protective molecule against heat-induced brain damage. Manipulation of HO-1 may provide a potential therapeutic approach for heat-related diseases.

Astaxanthin activates nuclear factor erythroid-related factor 2 and the antioxidant responsive element (Nrf2-ARE) pathway in the brain after subarachnoid hemorrhage in rats and attenuates early brain injury.

Astaxanthin (ATX) has been proven to ameliorate early brain injury (EBI) after experimental subarachnoid hemorrhage (SAH) by modulating cerebral oxidative stress. This study was performed to assess the effect of ATX on the Nrf2-ARE pathway and to explore the underlying molecular mechanisms of antioxidant properties of ATX in EBI after SAH. A total of 96 male SD rats were randomly divided into four groups. Autologous blood was injected into the prechiasmatic cistern of the rat to induce an experimental SAH model. Rats in each group were sacrificed at 24 h after SAH. Expressions of Nrf2 and heme oxygenase-1 (HO-1) were measured by Western blot and immunohistochemistry analysis. The mRNA levels of HO-1, NAD (P) H: quinone oxidoreductase 1 (NQO-1), and glutathione S-transferase-α1 (GST-α1) were determined by real-time polymerase chain reaction (PCR). It was observed that administration of ATX post-SAH could up-regulate the cortical expression of these agents, mediated in the Nrf2-ARE pathway at both pretranscriptional and posttranscriptional levels. Meanwhile, oxidative damage was reduced. Furthermore, ATX treatment significantly attenuated brain edema, blood–brain barrier (BBB) disruption, cellular apoptosis, and neurological dysfunction in SAH models. This study demonstrated that ATX treatment alleviated EBI in SAH model, possibly through activating the Nrf2-ARE pathway by inducing antioxidant and detoxifying enzymes.

Down-Regulation of HO-1 Promoted Apoptosis Induced By Decitabine Via Increasing p15INK4B Promoter Demethylation in myelodysplastic syndrome

Background: Decitabine, reverts hypermethylation of p15INK4B gene in vitro, was used to improves cytopenias and blast excess in over 50% of patients with high-risk myelodys plastic syndrome (MDS). In this study, over-expression of Heme Oxygenase-1(HO-1) was found in MDS cells line SKM-1 cells, and it was closely related to resistance to apoptosis induced by decitabine.Objective: we aimed to further investigated what role of HO-1 exactly played in apoptosis induced by low-does of decitabine in MDS.Method: CCK-8 kits was used to determine the proliferation inhibition of SKM-1 cells. Flow cytometry was used for analyzing cell proliferation rate and apoptosis. The methylation status and expression of P15INK4B in mRNA and protein levels were measured by methylation-specifc polymerase chain reaction (PCR [MSP]). Apoptosis relative factors expression were detected by real-time transcription and Western blot.Result: Up-regulation of HO-1 by transfected it into SKM-1 cells via lenti-virus vector promoted proliferation and protected cells against apoptosis. In contrast, down-regulation of HO-1 enhanced decitabine-induced apoptosis but reduced accumulation of S phase in cell cycle. To explore the mechanism, we detected cell cycle relative protein expression after SKM-1 cells were treated by decitabine in each group. As a result, over-expression of p15INK4B and CDK4 were observed in SKM-1 cells which HO-1 was inhibited. And p15INK4B and CDK4 expression-dependent apoptosis was related to caspase3 pathway. Even though HO-1 was silenced, but apoptotic rate never increased as caspase3 pathway was blocked.Conclusion: As we known that p15INK4B is a keypoint to regulate S phase of cell cycle, in our study, more obvious demethylation of p15INK4B was seen in group of SKM-1 cells in which HO-1 was down-regulated. It’s equally in patients’ mononuclear cells who suffered from MDS. The worse the prognosis of MDS was judged, the more the mRNA level of HO-1 expressed. In conclusion, over-expression of HO-1 indicated resistance to demethylation of p15INK4B induced by decitabine. DisclosuresNo relevant conflicts of interest to declare.

Homocysteine downregulates gene expression of heme oxygenase-1 in hepatocytes.

BackgroundHyperhomocysteinemia (HHcy) is an independent risk factor for liver diseases, such as fatty liver and hepatic fibrosis. However, the mechanisms underlying this pro-oxidative effect of homocysteine (Hcy) in hepatocytes remain largely unknown. Thus, we investigated the effect of Hcy on the gene expression of heme oxygenase-1 (HO-1), the primary rate-limiting enzyme in heme catabolism and a key anti-oxidant detoxification enzyme in maintaining cellular redox homeostasis.MethodsIn vivo, twenty male C57BL/6 mice at 8 weeks of age were randomly divided into two groups. One group was fed a chow diet (chow group; n = 10), the other group of mice was fed a methionine-supplemented diet (Met group, 1 mg kg−1 day−1 L-methionine in drinking water; n = 10) for 4 weeks. In vitro, HepG2 cells were stimulated with different doses of homocysteine (Hcy).ResultsFour weeks’ methionine supplementation caused a significant increase of plasma Hcy concentration and a decrease of HO-1 expression in the liver of C57BL/6 mice than mice received chow diet. Besides, SOD enzyme activities were impaired and the level of oxidative stress markers, such as malondialdehyde (MDA) were elevated in the liver from mice supplemented with methionine compared with control mice. In cultured hepatocytes, Hcy treatment reduced both the mRNA and protein levels of HO-1 dose-dependently. However, Hcy had no effect on the gene expression of Nrf2, the major transcriptional regulator of HO-1. Instead, Hcy induced the expression of Bach1, a transcriptional repressor of HO-1. In addition, Hcy stimulated the nuclear localization of Bach1 but prevented that of Nrf2. Furthermore, we found that knockdown of Bach1 attenuated the suppression of the HO-1 expression by Hcy.ConclusionsCollectively, our results demonstrated that Bach1 plays an important role in Hcy-triggered ROS generations through inhibiting HO-1 expression, likely, resulting from the disturbed interplay between Bach1 and Nrf2.Electronic supplementary materialThe online version of this article (doi:10.1186/1743-7075-11-55) contains supplementary material, which is available to authorized users.