Metformin alleviates spinal cord injury by inhibiting nerve cell ferroptosis through upregulation of heme oxygenase-1 expression

Previous studies have reported upregulation of heme oxygenase-1 in different central nervous system injury models.Heme oxygenase-1 plays a critical anti-inflammatory role and is essential for regulating cellular redox homeostasis.Metformin is a classic drug used to treat type 2 diabetes that can inhibit ferroptosis.Previous studies have shown that,when used to treat cardiovascular and digestive system diseases,metformin can also upregulate heme oxygenase-1 expression.Therefore,we hypothesized that heme oxygenase-1 plays a significant role in mediating the beneficial effects of metformin on neuronal ferroptosis after spinal cord injury.To test this,we first performed a bioinformatics analysis based on the GEO database and found that heme oxygenase-1 was upregulated in the lesion of rats with spinal cord injury.Next,we confirmed this finding in a rat model of T9 spinal cord compression injury that exhibited spinal cord nerve cell ferroptosis.Continuous intraperitoneal injection of metformin for 14 days was found to both upregulate heme oxygenase-1 expression and reduce neuronal ferroptosis in rats with spinal cord injury.Subsequently,we used a lentivirus vector to knock down heme oxygenase-1 expression in the spinal cord,and found that this significantly reduced the effect of metformin on ferroptosis after spinal cord injury.Taken together,these findings suggest that metformin inhibits neuronal ferroptosis after spinal cord injury,and that this effect is partially dependent on upregulation of heme oxygenase-1.

Fibroblast growth factor 21 inhibits ferroptosis following spinal cord injury by regulating heme oxygenase-1

Interfering with the ferroptosis pathway is a new strategy for the treatment of spinal cord injury.Fibroblast growth factor 21 can inhibit ferro ptosis and promote neurofunctional recovery,while heme oxygenase-1 is a regulator of iron and reactive oxygen species homeostasis.The relationship between heme oxygenase-1and ferroptosis remains controve rsial.In this study,we used a spinal co rd injury rat model to show that the levels of fibroblast growth factor 21 in spinal co rd tissue decreased after spinal cord injury.In addition,there was a significant aggravation of ferroptosis and a rapid increase in heme oxygenase-1 expression after spinal cord injury.Furthe r,heme oxygenase-1 aggravated fe rroptosis after spinal cord injury,while fibroblast growth factor 21 inhibited fe rroptosis by downregulating heme oxygenase-1.Thus,the activation of fibroblast growth factor 21 may provide a potential treatment for spinal co rd injury.These findings could provide a new potential mechanistic explanation for fibroblast growth factor 21 in the treatment of spinal cord injury.

Suppressing high mobility group box-1 release alleviates morphine tolerance via the adenosine5'-monophosphate-activated protein kinase/heme oxygenase-1 pathway

Opioids,such as morphine,are the most potent drugs used to treat pain.Long-term use results in high tolerance to morphine.High mobility group box-1(HMGB1) has been shown to participate in neuropathic or inflammatory pain,but its role in morphine tolerance is unclear.In this study,we established rat and mouse models of morphine tolerance by intrathecal injection of morphine for 7 consecutive days.We found that morphine induced rat spinal cord neurons to release a large amount of HMGB1.HMGB1 regulated nuclear factor κB p65 phosphorylation and interleukin-1β production by increasing Toll-like receptor 4receptor expression in microglia,thereby inducing morphine tolerance.Glycyrrhizin,an HMGB1 inhibito r,markedly attenuated chronic morphine tole rance in the mouse model.Finally,compound C(adenosine 5’-monophosphate-activated protein kinase inhibitor) and zinc protoporphyrin(heme oxygenase-1 inhibitor)alleviated the morphine-induced release of HMGB1 and reduced nuclear factor κB p65 phosphorylation and interleukin-1β production in a mouse model of morphine tolerance and an SH-SY5Y cell model of morphine tole rance,and alleviated morphine tolerance in the mouse model.These findings suggest that morphine induces HMGB1 release via the adenosine 5’-monophosphate-activated protein kinase/heme oxygenase-1 signaling pathway,and that inhibiting this signaling pathway can effectively reduce morphine tole rance.

Designing Artemisinins with Antimalarial Potential, Combining Molecular Electrostatic Potential, Ligand-Heme Interaction and Multivariate Models

Artemisinins tested against W-2 strains of malaria falciparum are investigated with molecular electrostatic potential (MEP), in an attempt to identify key features of the compounds that are necessary for their activities, as well as to investigate likely interactions with the receptor in a biological process and to use that information to propose new molecules. In order to discover the best geometry involving the ligand-receptor complexes (heme) studied and help in the proposition of the new derivatives, molecular simulations of interactions between the most negative charged region around the peroxide and heme locates (the ones around the Fe2+ ion) were carried out. In addition, PCA (principal components analysis), HCA (hierarchical cluster analysis), SDA (stepwise discriminant analysis), and KNN (K-nearest neighbor) multivariate models were employed to investigate which descriptors are responsible for the classification between the higher and lower antimalarial activity of the compounds, and also this information was used to propose new potentially active molecules. The information accumulated in studies of MEP, molecular docking, and multivariate analysis supported the proposal of new structures with potential antimalarial activities. The multivariate models constructed were applied to the new structures and indicated numbers 19 and 20 as the most prominent for syntheses and biological assays.

Overexpression of heme oxygenase-1 protects smooth muscle cells against oxidative injury and inhibits cell proliferation

To investigate whether the expression of exogenous heme oxygenase-1 (HO-1) gene within vascular smooth muscle cells (VSMC) could protect the cells from free radical attack and inhibit cell proliferation, we established an in vitro transfection of human HO-1 gene into rat VSMC mediated by a retroviral vector. The results showed that the profound expression of HO-1 protein as well as HO activity was 1.8- and 2.0-fold increased respectively in the transfected cells compared to the non-transfected ones. The treatment of VSMC with different concentrations of H2O2 led to the remarkable cell damage as indicated by survival rate and LDH leakage. However, the resistance of the HO-1 transfected VSMC against H2O2 was significantly raised. This protective effect was dramatically diminished when the transfected VSMC were pretreated with ZnPP-IX, a specific inhibitor of HO, for 24 h. In addition, we found that the growth potential of the transfected cells was significantly inhibited directly by increased activity of HO-1, and this effect might be related to decreased phosphorylation of MAPK. These results suggest that the overexpression of introduced hHO-1 is potentially able to reduce the risk factors of atherosclerosis, partially due to its cellular protection against oxidative injury and to its inhibitory effect on cellular proliferation.

Heme in intestinal epithelial cell turnover, differentiation, detoxification, inflammation, carcinogenesis, absorption and motility

The gastrointestinal tract is lined by a simple epithelium that undergoes constant renewal involving cell division, differentiation and cell death. In addition, the epithelial lining separates the hostile processes of digestion and absorption that occur in the intestinal lumen from the aseptic environment of the internal milieu by defensive mechanisms that protect the epithelium from being breached. Central to these defensive processes is the synthesis of heme and its catabolism by heme oxygenase （HO）. Dietary heme is also an important source of iron for the body which is taken up intact by the enterocyte. This review describes the recent literature on the diverse properties of heme/HO in the intestine tract. The roles of heme/HO in the regulation of the cell cycle/ apoptosis, detoxification of xenobiotics, oxidative stress, inflammation, development of colon cancer, hemeiron absorption and intestinal motility are specifically examined.

Region-dependent effects of diabetes and insulin-replacement on neuronal nitric oxide synthase-and heme oxygenase-immunoreactive submucous neurons

AIM To investigate the intestinal segment-specific effects of diabetes and insulin replacement on the density of different subpopulations of submucous neurons. METHODS Ten weeks after the onset of type 1 diabetes samples were taken from the duodenum, ileum and colon of streptozotocin-induce diabetic, insulin-treated diabetic and sex-and age-matched control rats. Whole-mount preparations of submucous plexus were prepared from the different gut segments for quantitative fluorescent immunohistochemistry. The following double-immunostainings were performed: neuronal nitric oxide synthase(n NOS) and Hu C/D, heme oxygenase(HO) 1 and peripherin, as well as HO2 and peripherin. The density of n NOS-, HO1-and HO2-immunoreactive(IR) neurons was determined as a percentage of the total number of submucous neurons. RESULTS The total number of submucous neurons and the proportion of n NOS-, HO1-and HO2-IR subpopulations were not affected in the duodenal ganglia of control, diabetic and insulin-treated rats. While the total neuronal number did not change in either the ileum or the colon, the density of nitrergic neurons exhibited a 2-and 3-fold increase in the diabetic ileum and colon, respectively, which was further enhanced after insulin replacement. The presence of HO1-and HO2-IR submucous neurons was robust in the colon of controls(38.4%-50.8%), whereas it was significantly lower in the small intestinal segments(0.0%-4.2%, P < 0.0001). Under pathophysiological conditions the only alteration detected was an increase in the ileum and a decrease in the colon of the proportion of HO-IR neurons in insulin-treated diabetic animals. CONCLUSION Diabetes and immediate insulin replacement induce the most pronounced region-specific alterations of n NOS-, HO1-and HO2-IR submucous neuronal density in the distal parts of the gut.

鸡Hemeo xygenase 1基因克隆、结构功能预测及组织表达特性分析

旨在克隆鸡Hteme oxygenase 1(HO-1)基因,探明其蛋白结构、功能及组织表达特性。以海兰白鸡(W-36)为材料,利用RT-PCR技术克隆鸡HO-1基因CDS区,利用生物信息学方法预测蛋白结构与功能,应用qRT-PCR检测组织表达特性。结果表明,鸡HO-1基因的CDS为891bp,编码296个氨基酸,其核苷酸和氨基酸序列与其他种属间的差异较大。鸡HO-1为跨膜非分泌蛋白,具有HO家族的结构域,酶分类为EC1.14.99.3,能够结合-HEM、BLA、OXN、Q80、SUC、TRE和Na^+等分子。鸡HO-1基因在组织内广泛表达,在动脉、脑干、大脑、坐骨神经、十二指肠及小肠等组织表达量较高。预测HO-1蛋白具有调控糖类和盐类等相关分子功能作用,其在组织中广泛表达,在循环系统、神经系统和消化系统中具有重要的生物学功能。

Hepatic steatosis prevents heme oxygenase-1 induction by isoflurane in the rat liver

AIM:To characterize the inductive effects of isoflurane(ISO) on hepatic heme oxygenase-1(HO-1) in an animal model of hepatic steatosis.METHODS:Lean(LEAN) and obese(FAT) Zucker rats were randomized into 4 groups:1:LEAN + pentobarbital sodium(PEN);2:LEAN + ISO;3:FAT + PEN;4:FAT + ISO.The animals were mechanically ventilated for 6 h.In vitro analyses of liver tissue included determination of HO-1 mRNA and protein expression as well as measurement of HO enzyme activity and immunohistochemical analyses.RESULTS:Compared to PEN treatment,ISO administration profoundly induced hepatic HO-1 mRNA and protein expression and significantly increased HO enzyme activity in lean Zucker rats.In contrast,no difference in HO-1 gene expression was observed after ISO or PEN anesthesia in obese Zucker rats.CONCLUSION:The present study demonstrates that ISO is an inducer of hepatic HO-1 gene expression in non-steatotic organs but failed to upregulate HO-1 in steatotic livers.

Heme oxygenase-1 protects donor livers from ischemia/reperfusion injury:The role of Kupffer cells

AIM:To examine whether heme oxygenase (HO)-1 overexpression would exert direct or indirect effects on Kupffer cells activation, which lead to aggravation of reperfusion injury.METHODS: Donors were pretreated with cobalt protoporphyrin (CoPP) or zinc protoporphyrin (ZnPP), HO-1 inducer and antagonist, respectively. Livers were stored at 4℃ for 24 h before transplantation. Kupffer cells were isolated and cultured for 6 h after liver reperfusion.RESULTS: Postoperatively, serum transaminases were significantly lower and associated with less liver injury when donors were pretreated with CoPP, as compared with the ZnPP group. Production of the cytokines tumor necrosis factor-α and interleukin-6 generated by Kupffer cells decreased in the CoPP group. The CD14 expression levels (RT-PCR/Western blots) of Kupffer cells from CoPP-pretreated liver grafts reduced.CONCLUSION: The study suggests that the potential utility of HO-1 overexpression in preventing ischemia/reperfusion injury results from inhibition of Kupffer cells activation.

Heme oxygenase system in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (IRI) limits access to transplantation. Heme oxygenase-1 (HO-1) is a powerful antioxidant enzyme which degrades free heme into biliverdin,free iron and carbon monoxide. HO-1 and its metabolites have the ability to modulate a wide variety of inflammatory disorders including hepatic IRI. Mechanisms of this protective effect include reduction of oxygen free radicals,alteration of macrophage and T cell phenotype. Further work is required to understand the physiological importance of the many actions of HO-1 identified experimentally,and to harness the protective effect of HO-1 for therapeutic potential.

Inhibiting heme oxygenase-1 attenuates rat liver fibrosis by removing iron accumulation

AIM:To investigate the effects of the heme oxygenase(HO)-1/carbon monoxide system on iron deposition and portal pressure in rats with hepatic fibrosis induced by bile duct ligation(BDL).METHODS:Male Sprague-Dawley rats were divided randomly into a Sham group,BDL group,Fe group,deferoxamine(DFX) group,zinc protoporphyrin(ZnPP) group and cobalt protoporphyrin(CoPP) group.The levels of HO-1 were detected using different methods.The serum carboxyhemoglobin(COHb),iron,and portal vein pressure(PVP) were also quantified.The plasma and mRNA levels of hepcidin were measured.Hepatic fibrosis and its main pathway were assessed using Van Gieson's stain,hydroxyproline,transforming growth factor-β1(TGF-β1),nuclear factor-E2-related factor 2(Nrf2),matrix metalloproteinase-2(MMP-2) and tissue inhibitor of metalloproteinase-1(TIMP-1).RESULTS:Serum COHb and protein and mRNA expression levels of HO-1 and Nrf2 were increased in the BDL group compared with the Sham group and were much higher in the CoPP group.The ZnPP group showed lower expression of HO-1 and Nrf2 and lower COHb.The levels of iron and PVP were enhanced in the BDL group but were lower in the ZnPP and DFX groups and were higher in the CoPP and Fe groups.Hepcidin levels were higher,whereas superoxide dismutase levels were increased and malonaldehyde levels were decreased in the ZnPP and DFX groups.The ZnPP group also showed inhibited TGF-β1 expression and regulated TIMP-1/MMP-2 expression,as well as obviously attenuated liver fibrosis.CONCLUSION:Reducing hepatic iron deposition and CO levels by inhibiting HO-1 activity though the Nrf2/Keap pathway could be helpful in improving hepatic fibrosis and regulating PVP.

Heme oxygenase-1 as a therapeutic target in inflammatory disorders of the gastrointestinal tract

Heme oxygenase (HO)-1 is the inducible isoform of the first and rate-limiting enzyme of heme degradation. HO-1 not only protects against oxidative stress and apoptosis, but has received a great deal of attention in recent years because ofits potent anti-inflammatory functions. Studies with HO-1 knockout animal models have led to major advances in the understanding of how HO-1 might regulate inflammatory immune responses, although little is known on the underlying mechanisms. Due to its beneficial effects the targeted induction of this enzyme is considered to have major therapeutic po- tential for the treatment ofinflammatory disorders. This review discusses current knowledge on the mechanisms that mediate anti-inflammatory protection by HO-1. More specifically, the article deals with the role of HO-1 in the pathophysiology of viral hepatitis, inflammatorybowel disease, and pancreatitis. The effects of specific HO-1 modulation as a potential therapeutic strategy in experimental cell culture and animal models of these gastrointestinal disorders are summarized. In conclusion, targeted regulation of HO-1 holds major promise for future clinical interventions in inflammatory diseases of the gastrointestinal tract.

Heme oxygenase-1 protects rat liver against warm ischemia/reperfusion injury via TLR2/TLR4-triggered signaling pathways

AIM:To investigate the efficacy and molecularmechanisms of induced heme oxygenase(HO)-1 in protecting liver from warm ischemia/reperfusion(I/R)injury.METHODS:Partial warm ischemia was produced in the left and middle hepatic lobes of SD rats for 75min,followed by 6 h of reperfusion.Rats were treated with saline,cobalt protoporphyrin(Co PP)or zinc protoporphyrin(Zn PP)at 24 h prior to the ischemia insult.Blood and samples of ischemic lobes subjected to ischemia were collected at 6 h after reperfusion.Serum transaminases level,plasma lactate dehydrogenase and myeloperoxidase activity in liver were measured.Liver histological injury and inflammatory cell infiltration were evaluated by tissue section and liver immunohistochemical analysis.We used quantitative reverse transcription polymerase chain reaction to analyze liver expression of inflammatory cytokines and chemokines.The cell lysates were subjected to immunoprecipitation with anti-Toll-IL-1R-containing adaptor inducing interferon-β(TRIF)and anti-myeloid differentiation factor 88(My D88),and then the immunoprecipitates were analyzed by SDS-PAGE and immunoblotted with the indicated antibodies.RESULTS:HO-1 protected livers from I/R injury,as evidenced by diminished liver enzymes and wellpreserved tissue architecture.In comparison with Zn PP livers 6 h after surgery,Co PP treatment livers showed a significant increase inflammatory cell infiltration of lymphocytes,plasma cells,neutrophils and macrophages.The Toll-like receptor(TLR)-4 and TANK binding kinase1 protein levels of rats treated with Co PP significantly reduced in TRIF-immunoprecipitated complex,as compared with Zn PP treatment.In addition,pretreatment with Co PP reduced the expression levels of TLR2,TLR4,IL-1R-associated kinase(IRAK)-1 and tumor necrosis factor receptor-associated factor 6 in My D88-immunoprecipitated complex.The inflammatory cytokines and chemokines m RNA expression rapidly decreased inCo PP-pretreated liver,compared with the Zn PP-treated group.However,the expression of negative regulators Tollinteracting protein,suppressor of cytokine signaling-1,IRAK-M and Src homology 2 domain-containing inositol-5-phosphatase-1 in Co PP treatment rats were markedly up-regulated as compared with Zn PP-treated rats.CONCLUSION:HO-1 protects liver against I/R injury by inhibiting TLR2/TLR4-triggered My D88-and TRIFdependent signaling pathways and increasing expression of negative regulators of TLR signaling in rats.

Cytoprotective role of heme oxygenase-1 and heme degradation derived end products in liver injury

The activation of heme oxygenase-1(HO-1) appears to be an endogenous defensive mechanism used by cells to reduce inflammation and tissue damage in a number of injury models. HO-1, a stress-responsive enzyme that catabolizes heme into carbon monoxide(CO), biliverdin and iron, has previously been shown to protect grafts from ischemia/reperfusion and rejection.In addition, the products of the HO-catalyzed reaction, particularly CO and biliverdin/bilirubin, have been shown to exert protective effects in the liver against a number of stimuli, as in chronic hepatitis C and in transplanted liver grafts. Furthermore, the induction of HO-1 expression can protect the liver against damage caused by a number of chemical compounds. More specifically, the CO derived from HO-1-mediated heme catabolism has been shown to be involved in the regulation of inflammation; furthermore, administration of low concentrations of exogenous CO has a protective effect against inflammation. Both murine and human HO-1 deficiencies have systemic manifestations associated with iron metabolism, such as hepatic overload(with signs of a chronic hepatitis) and iron deficiency anemia(with paradoxical increased levels of ferritin).Hypoxia induces HO-1 expression in multiple rodent,bovine and monkey cell lines, but interestingly, hypoxia represses expression of the human HO-1 gene in a variety of human cell types(endothelial cells, epithelial cells, T cells). These data suggest that HO-1 and CO are promising novel therapeutic molecules for patients with inflammatory diseases. In this review, we present what is currently known regarding the role of HO-1 in liver injuries and in particular, we focus on the implications of targeted induction of HO-1 as a potential therapeutic strategy to protect the liver against chemically induced injury.

Heme oxygenase-1 and gut ischemia/reperfusion injury: A short review

Ischemia/reperfusion (I/R) injury of the gut is a significant problem in a variety of clinical settings and is associated with a high morbidity and mortality. Although the mechanisms involved in the pathogenesis of gut I/R injury have not been fully elucidated, it is generally believed that oxidative stress with subsequent inflammatory injury plays an important role. Heme oxygenase (HO) is the rate-limiting enzyme in the catabolism of heme, followed by production of CO, biliverdin, and free iron. The HO system is believed to confer cytoprotection by inhibiting inflammation, oxidation, and apoptosis, and maintaining microcirculation. HO-1, an inducible form of HO, serves a vital metabolic function as the rate-limiting step in the heme degradation pathway, and affords protection in models of intestinal I/R injury. HO-1 system is an important player in intestinal I/R injury condition, and may offer new targets for the management of this condition.

Quercetin protects against diabetic retinopathy in rats by inducing heme oxygenase-1 expression

Quercetin is a widely-occurring flavonoid that protects against cancer, and improves memory and cardiovascular functions.However, whether quercetin exhibits therapeutic effects in diabetic retinopathy remains unclear.In this study, we established a rat model of streptozocininduced diabetic retinopathy.Seventy-two hours later, the rats were intraperitoneally administered 150 mg/kg quercetin for 16 successive weeks.Quercetin markedly increased the thickness of the retinal cell layer, increased the number of ganglion cells, and decreased the overexpression of the pro-inflammatory factors interleukin-1β, interleukin-18, interleukin-6 and tumor necrosis factor-α in the retinal tissue as well as the overexpression of high mobility group box-1 and the overactivation of the NLRP3 inflammasome.Furthermore, quercetin inhibited the overexpression of TLR4 and NF-κBp65, reduced the expression of the pro-angiogenic vascular endothelial growth factor and soluble intercellular adhesion molecule-1, and upregulated the neurotrophins brain-derived neurotrophic factor and nerve growth factor.Intraperitoneal injection of the heme oxygenase-1 inhibitor zinc protoporphyrin blocked the protective effect of quercetin.These findings suggest that quercetin exerts therapeutic effects in diabetic retinopathy possibly by inducing heme oxygenase-1 expression.This study was approved by the Animal Ethics Committee of China Medical University, China(approval No.2016 PS229K) on April 8, 2016.

Effects of heme oxygenase-1-modified bone marrow mesenchymal stem cells on microcirculation and energy metabolism following liver transplantation

AIM To investigate the effects of heme oxygenase-1(HO-1)-modified bone marrow mesenchymal stem cells(BMMSCs)on the microcirculation and energy metabolism of hepatic sinusoids following reduced-size liver transplantation(RLT)in a rat model.METHODS BMMSCs were isolated and cultured in vitro using an adherent method,and then transduced with HO-1-bearing recombinant adenovirus to construct HO-1/BMMSCs.A rat acute rejection model following 50%RLT was established using a two-cuff technique.Recipients were divided into three groups based on the treatment received:normal saline(NS),BMMSCs and HO-1/BMMSCs.Liver function was examined at six time points.The levels of endothelin-1(ET-1),endothelial nitric-oxide synthase(e NOS),inducible nitric-oxide synthase(i NOS),nitric oxide(NO),and hyaluronic acid(HA)were detected using an enzyme-linked immunosorbent assay.The portal vein pressure(PVP)was detected by Power Lab ML880.The expressions of ET-1,i NOS,e NOS,and von Willebrand factor(v WF)protein in the transplanted liver were detected using immunohistochemistry and Western blotting.ATPase in the transplanted liver was detected by chemical colorimetry,and the ultrastructural changes were observed under a transmission electron microscope.RESULTS HO-1/BMMSCs could alleviate the pathological changes and rejection activity index of the transplanted liver,and improve the liver function of rats following 50%RLT,with statistically significant differences compared with those of the NS group and BMMSCs group(P<0.05).In term of the microcirculation of hepatic sinusoids:The PVP on POD7 decreased significantly in the HO-1/BMMSCs and BMMSCs groups compared with that of the NS group(P<0.01);HO-1/BMMSCs could inhibit the expressions of ET-1 and i NOS,increase the expressions of e NOS and inhibit amounts of NO production,and maintain the equilibrium of ET-1/NO(P<0.05);and HO-1/BMMSCs increased the expression of v WF in hepatic sinusoidal endothelial cells(SECs),and promoted the degradation of HA,compared with those of the NS group and BMMSCs group(P<0.05).In term of the energy metabolism of the transplanted liver,HO-1/BMMSCs repaired the damaged mitochondria,and improved the activity of mitochondrial aspartate aminotransferase(ASTm)and ATPase,compared with the other two groups(P<0.05).CONCLUSION HO-1/BMMSCs can improve the microcirculation of hepatic sinusoids significantly,and recover the energy metabolism of damaged hepatocytes in rats following RLT,thus protecting the transplanted liver.

Hydrogen-rich water protects against inflammatory bowel disease in mice by inhibiting endoplasmic reticulum stress and promoting heme oxygenase-1 expression

AIM To investigate the therapeutic effect of hydrogen-rich water(HRW) on inflammatory bowel disease(IBD) and to explore the potential mechanisms involved.METHODS Male mice were randomly divided into the following four groups: control group, in which the mice received equivalent volumes of normal saline(NS) intraperitoneally(ip); dextran sulfate sodium(DSS) group, in which the mice received NS ip(5 m L/kg body weight, twice per day at 8 am and 5 pm) for 7 consecutive days after IBD modeling; DSS + HRW group, in which the mice received HRW(in the same volume as the NS treatment) for 7 consecutive days after IBD modeling; and DSS + HRW + Zn PP group, in which the mice received HRW(in the same volume as the NS treatment) and ZnP P [a heme oxygenase-1(HO-1) inhibitor, 25 mg/kg] for 7 consecutive days after IBD modeling. IBD was induced by feeding DSS to the mice, and blood and colon tissues were collected on the 7th d after IBD modeling to determine clinical symptoms, colonic inflammation and the potential mechanisms involved.RESULTS The DSS + HRW group exhibited significantly attenuated weight loss and a lower extent of disease activity index compared with the DSS group on the 7th d(P < 0.05). HRW exerted protective effects against colon shortening and colonic wall thickening in contrast to the DSS group(P < 0.05). The histological study demonstrated milder inflammation in the DSS + HRW group, which was similar to normal inflammatory levels, and the macroscopic and microcosmic damage scores were lower in this group than in the DSS group(P < 0.05). The oxidative stress parameters, including MDA and MPO in the colon, were significantly decreased in the DSS + HRW group compared with the DSS group(P < 0.05). Simultaneously, the protective indicators, superoxide dismutase and glutathione, were markedly increased with the use of HRW. Inflammatory factors were assessed, and the results showed that the DSS + HRW group exhibited significantly reduced levels of TNF-α, IL-6 and IL-1β compared with the DSS group(P < 0.05). In addition, the pivotal proteins involved in endoplasmic reticulum(ER) stress, including p-e IF2α, ATF4, XBP1 s and CHOP, were dramatically reduced after HRW treatment in contrast to the control group(P < 0.05). Furthermore, HRW treatment markedly up-regulated HO-1 expression, and the use of Zn PP obviously reversed the protective role of HRW. In the DSS + HRW + ZnP P group, colon shortening and colonic wall thickening were significantly aggravated, and the macroscopic damage scores were similar to those of the DSS + HRW group(P < 0.05). The histological study also showed more serious colonic damage that was similar to the DSS group.CONCLUSION HRW has a significant therapeutic potential in IBD by inhibiting inflammatory factors, oxidative stress and ER stress and by up-regulating HO-1 expression.

Rosmarinic acid elicits neuroprotection in ischemic stroke via Nrf2 and heme oxygenase 1 signaling

Rosmarinic acid（RA） can elicit a neuroprotective effect against ischemic stroke, but the precise molecular mechanism remains poorly understood. In this study, an experimental ischemic stroke model was established in CD-1 mice（Beijing Vital River Laboratory Animal Technology, Beijing, China） by occluding the right middle cerebral artery for 1 hour and allowing reperfusion for 24 hours. After intraperitoneally injecting model mice with 10, 20, or 40 mg/kg RA, functional neurological deficits were evaluated using modified Longa scores. Subsequently, cerebral infarct volume was measured using TTC staining and ischemic brain tissue was examined for cell apoptosis with TUNEL staining. Superoxide dismutase activity and malondialdehyde levels were measured by spectrophometry. Expression of heme oxygenase-1（HO-1）, nuclear factor erythroid 2-related factor 2（Nrf2）, Bcl-2, Bax, Akt, and phospho-Ser473 Akt proteins in ischemic brain tissue was detected by western blot, while mRNA levels of Nrf2, HO-1, Bcl-2, and Bax were analyzed using real time quantitative PCR. In addition, HO-1 enzyme activity was measured spectrophotometrically. RA（20 and 40 mg/kg） greatly improved neurological function, reduced infarct volume, decreased cell apoptosis, upregulated Bcl-2 protein and mRNA expression, downregulated Bax protein and mRNA expression, increased HO-1 and Nrf2 protein and mRNA expression, increased superoxide dismutase activity, and decreased malondialdehyde levels in ischemic brain tissue of model mice. However, intraperitoneal injection of a HO-1 inhibitor（10 mg/kg zinc protoporphyrin IX） reversed the neuroprotective effects of RA on HO-1 enzyme activity and Bcl-2 and Bax protein expression. The PI3 K/Akt signaling pathway inhibitor LY294002（10 mM） inhibited Akt phosphorylation, as well as Nrf2 and HO-1 expression. Our findings suggest that RA has anti-oxidative and anti-apoptotic properties that protect against ischemic stroke by a mechanism involving upregulation of Nrf2 and HO-1 expression via the PI3 K/Akt signaling pathway.