Involvement Of Heme Oxygenase-1 Research Articles

Molecular docking study and antireabsorptive activity of a semi-synthetic coumarin derivative from Platymiscium floribundum in the ligature-induced periodontitis in rats: the involvement of heme oxygenase-1.

This study aimed to evaluate the anti-resorptive activity of a semi-synthetic coumarin derivative from Platymiscium floribundum, named 6,7-dimethoxy-3-nitrocoumarin. Molecular docking studies were performed to test the binding performance of the derivative against targets associated with alveolar bone loss (TNF-α, IL-1β, and catalase) and a target considered an antioxidant defense (HO-1) during periodontitis. Periodontitis was induced by placing a nylon ligature around the second molars. The rats received for 11days 6,7-dimethoxy-3-nitrocoumarin (0.01, 0.1, or 1mg/kg) or vehicle. We investigated by RT-qPCR analysis (TNF-α, IL-1β, and HO-1 mRNA expression levels) and by colorimetric assay (catalase activity) the mechanism of action mediated by 6,7-dimethoxy-3-nitrocoumarin. The in vivo toxicity of 6,7-dimethoxy-3-nitrocoumarin was evaluated. 6,7-Dimethoxy-3-nitrocoumarin (0.1 or 1mg/kg) reduced alveolar bone loss (1.05 ± 0.24), when compared to vehicle-treated group (3.05 ± 0.30). The interactions of 6,7-dimethoxy-3-nitrocoumarin and the four targets (TNF-α, IL-1β, catalase, and HO-1) showed firm bonds above 6.0kcal/mol. 6,7-dimethoxy-3-nitrocoumarin (1mg/kg) lowered mRNA expression levels of TNF-α (2.33 ± 0.56) and IL-1β (19.87 ± 2.9), while it increased both the mRNA expression levels of HO-1 (43.40 ± 1.05) and the catalase activity (46.42 ± 4.59), when compared to vehicle-treated group (46.29 ± 8.43; 37.83 ± 4.38; 1.58 ± 0.11; 8.93 ± 1.86, respectively). The animals did not show any signs of toxicity. 6,7-Dimethoxy-3-nitrocoumarin decreased inflammatory bone loss in the ligature-induced periodontitis in rats, and the activation of the HO-1 pathway may contribute, at least partially, to its protective effects by reducing TNF-α and IL-1β mRNA levels and increasing catalase activity. 6,7-Dimethoxy-3-nitrocumarin could be used as an adjunct to subgingival instrumentation during active and supportive periodontal treatment.

Role of inflammatory, oxidative, and ER stress signaling in the neuroprotective effect of atorvastatin against doxorubicin-induced cognitive impairment in rats.

Doxorubicin (DOX) is a potent chemotherapeutic agent widely used for the treatment of several malignancies. Despite its effectiveness, DOX has been implicated in induced neurotoxicity manifested as cognitive dysfunction with varying degrees, commonly referred to as chemobrain. DOX-induced chemobrain is presumed to be due to cytokine-induced inflammatory, oxidative, and apoptotic responses damaging the brain. Atorvastatin (ATV), 3-hydroxy 3-methylglutaryl co-enzyme A (HMG Co-A) reductase inhibitor, is a cholesterol-lowering statin possessing beneficial pleiotropic effects, including anti-inflammatory, antioxidant, and anti-apoptotic properties. Therefore, this study aims to investigate the potential neuroprotective effects of ATV against DOX-induced cognitive impairment studying the possible involvement of heme oxygenase-1 (HO-1) and endoplasmic reticulum (ER) stress biomarkers. Rats were treated with DOX (2 mg/kg/week), i.p. for 4 weeks. Oral treatment with ATV (10 mg/kg) ameliorated DOX-induced behavioral alterations, protected brain histological features, and attenuated DOX-induced inflammatory, oxidative, and apoptotic biomarkers. In addition, ATV upregulated the protective HO-1 expression levels and downregulated the DOX-induced apoptotic ER stress biomarkers. In conclusion, ATV (10 mg/kg) exhibited neuroprotective properties against DOX-induced cognitive impairment which could possibly be attributed to their anti-inflammatory, antioxidant, and anti-apoptotic effects in the brain.

Protective effects of Nrf2–ARE activator on dopaminergic neuronal loss in Parkinson disease model mice: Possible involvement of heme oxygenase-1

Parkinson disease (PD) is a neurodegenerative disorder characterized by a selective loss of dopaminergic neurons in the substantia nigra, and oxidative stress is thought to contribute to this pathogenesis. The nuclear factor erythroid 2-related factor 2 (Nrf2)–antioxidant response element (ARE) pathway, which induces the production of antioxidant enzymes, is thereby a potential target for therapeutics to reduce neurodegeneration in PD. Previously, we identified TPNA10168 from a chemical library as an activator of the Nrf2–ARE pathway, and the present study examined the effects of TPNA10168 on an in vivo PD model. Subcutaneous administration of TPNA10168 was associated with inhibited dopaminergic neuronal loss and behavioral impairment in 6-hydroxydopamine–induced PD model mice. Heme oxygenase-1 (HO-1) is an antioxidant enzyme expressed downstream of the Nrf2–ARE signaling pathway, and we observed that HO-1 protein levels were upregulated by TPNA10168 in the mouse brain. These results suggest that TPNA10168 inhibits dopaminergic neuronal death in PD model mice, and that upregulation of HO-1 might participate in this effect.

Involvement of heme oxygenase-1 in suppression of T cell activation by quercetin

Aim Acute rejection is still a major problem in transplantation and one of the most important causes of late graft loss. Cyclosporine and tacrolimus are widely used for suppression of T cell function to avoid graft rejection, but long-term use of these compounds is associated with serious toxicities. Quercetin, a flavonoid found in fruits and vegetables, has been demonstrated to exhibit cytoprotective effects through the induction of heme oxygenase (HO) -1, an enzyme involved in heme catabolism. We hypothesized that quercetin induces HO-1 in T cells and suppresses T cell function via HO-1. In the present study, we showed that quercetin suppressed the A23187-mediated expression of interleukin (IL) -2 in T cells. Methods Mouse splenocytes, enriched T cells, and EL4 cells, a mouse T cell line, were treated with quercetin, and then stimulated with A23187, a calcium ionophore, concanavalin A, or anti-CD3ε and anti-CD28 antibodies. Cell proliferation, expression of IL-2, calcium mobilization, apoptosis, cell cycle, and phosphorylation of extracellular signal-regulated kinase (ERK) were investigated. Results Quercetin induced HO-1, and this induction of HO-1 was implicated in the suppression of IL-2 production. Furthermore, the induction of HO-1 by quercetin suppressed the influx of calcium ions, a known trigger of IL-2 production. Additionally, quercetin suppressed T cell proliferation through promotion of cell cycle arrest via HO-1 induction, but quercetin did not induce apoptosis. To investigate the role of the signal transduction pathway in quercetin’s effect on cell proliferation, we evaluated the phosphorylation of ERK in T cells. Quercetin suppressed the A23187-mediated stimulation of ERK, an effect that was mediated through HO-1. These results suggested that HO-1 is involved in the suppressive effects of quercetin on T cell activation and proliferation. Conclusion Our findings indicate that the quercetin may be a promising candidate for inducing HO-1 in T cells, thereby facilitating immunosuppressive effects.

Sulfated polysaccharide from the green marine algae Caulerpa racemosa reduces experimental pain in the rat temporomandibular joint

Temporomandibular disorder is a clinical painful condition in the temporomandibular joint (TMJ) region. The purified sulfated polysaccharide from the green marine algae Caulerpa racemosa (Cr) has provided anti-inflammatory and antinociceptive activity. This study evaluated these effects on a TMJ hypernociception model. Wistar rats (180 - 250 g) were pre-treated (i.v.) with Cr at 0.01, 0.1, or 1 mg/kg or vehicle 30 min before formalin (1.5%/50 μL, i.art.), capsaicin (1.5%/20 μL, i.art.), or serotonin (225 μg/50 μL, i.art.) in the TMJ, and nociceptive behaviors were measured for 45 or 30 min upon inflammatory stimuli. Inflammatory parameters vascular permeability assay, TNF-α, and IL-1β by ELISA, protein expression of adhesion molecules ICAM-1 and CD55 by Western blot were assessed. The involvement of heme oxygenase-1 (HO-1) and nitric oxide (NO) pathways were assessed by pharmacological inhibition. Cr (1 mg/kg) reduced nociceptive behavior, plasmatic extravasation, TNF-α, and IL-1β levels, as well as ICAM-1 and CD55 expression in periarticular tissues. Cr antinociceptive effect was not prevented by aminoguanidine, but ZnPP-IX did reduce its antinociceptive effect. Therefore, Cr antinociceptive and anti-inflammatory effects in this experimental model of hypernociception depended on the HO-1 pathway integrity, as well as reducing peripheral inflammatory events, e.g., TNF-α and IL-1β cytokines levels, ICAM-1 and CD55 expression.

Protective Effect of 2',3'-Dihydroxy-4',6'-dimethoxychalcone on Glutamate-Induced Neurotoxicity in Primary Cortical Cultures.

We have previously isolated 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC) from green perilla leaves as the activator of the nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway. This study aims to evaluate the effects of DDC against glutamate neurotoxicity using rat primary cortical cultures. Treatment of cultures with DDC for 24 h before glutamate exposure significantly inhibited glutamate neurotoxicity in a concentration-dependent manner. The involvement of hemeoxygenase-1 (HO-1) and reduced glutathione (GSH) in the protective effects of DDC on cortical cultures was also evaluated. While an HO-1 inhibitor did not have a significant effect on DDC-induced neuroprotection, a γ-glutamylcystein synthetase (γ-GCS) inhibitor significantly suppressed the protective effect of DDC. In an astrocyte culture, DDC induced a marked increase in the levels of intracellular reduced GSH. These results suggest that DDC mainly activates the Nrf2-ARE pathway of astrocytes, resulting in the increased extracellular release of reduced GSH, protecting neurons from glutamate neurotoxicity.

Involvement of Heme Oxygenase-1 in Neuropsychiatric and Neurodegenerative Diseases.

Heme oxygenase (HO) family catalyzes the conversion of heme into free iron, carbon monoxide and biliverdin. It possesses two well-characterized isoforms: HO-1 and HO-2. Under brain physiological conditions, the expression of HO-2 is constitutive, abundant and ubiquitous, whereas HO-1 mRNA and protein are restricted to small populations of neurons and neuroglia. HO-1 is an inducible enzyme that has been shown to participate as an essential defensive mechanism for neurons exposed to oxidant challenges, being related to antioxidant defenses in certain neuropathological conditions. Considering that neurodegenerative diseases (Alzheimer's Disease (AD), Parkinson's Disease (PD) and Multiple Sclerosis (MS)) and neuropsychiatric disorders (depression, anxiety, Bipolar Disorder (BD) and schizophrenia) are associated with increased inflammatory markers, impaired redox homeostasis and oxidative stress, conditions that may be associated with alterations in HO-levels/activity, the purpose of this review is to present evidence on the possible role of HO-1 in these Central Nervous System (CNS) diseases. In addition, the possible therapeutic potential of targeting brain HO-1 is explored in this review.

Suppressive Effect of Fermented Angelica tenuissima Root Extract against Photoaging: Possible Involvement of Hemeoxygenase-1.

Angelica tenuissima root has historically been used as a traditional medicine in Korea. Previous studies have identified the anti-melanogenic effects of the extract of A. tenuissima root fermented by Aspergillus oryzae (FAT). This study investigated the protective effects of FAT against ultraviolet light B exposure (UVB; 30 mJ/cm2) in HaCaT (human keratinocyte) or Hs68 (human foreskin fibroblast) skin cells. FAT treatment was able to stimulate wound healing rate at the basal condition. FAT also favored the maintenance and/or improvement of extracellular matrix impairment caused by UVB irradiation through: 1) upregulation of procollagen Type-1 synthesis and secretion; 2) suppression of MMP-1 and elastase expression. FAT was able to play a role in the attenuation of inflammatory responses caused by UVB irradiation via upregulation of photo-protective hemeoxygease-1 and suppression of proinflammatory cyclooxygenase-2 expression. After further verification of the anti-photoaging potential of FAT, it could be utilized as an effective ingredient in anti-aging and anti-wrinkle cosmetics.

Alpha-7 nicotinic acetylcholine receptor agonist treatment in a rat model of Huntington's disease and involvement of heme oxygenase-1.

Neuroinflammation is a common element involved in the pathophysiology of neurodegenerative diseases. We recently reported that repeated alpha-7 nicotinic acetylcholine receptor (α7nAChR) activations by a potent agonist such as PHA 543613 in quinolinic acid-injured rats exhibited protective effects on neurons. To further investigate the underlying mechanism, we established rat models of early-stage Huntington's disease by injection of quinolinic acid into the right striatum and then intraperitoneally injected 12 mg/kg PHA 543613 or sterile water, twice a day during 4 days. Western blot assay results showed that the expression of heme oxygenase-1 (HO-1), the key component of the cholinergic anti-inflammatory pathway, in the right striatum of rat models of Huntington's disease subjected to intraperitoneal injection of PHA 543613 for 4 days was significantly increased compared to the control rats receiving intraperitoneal injection of sterile water, and that the increase in HO-1 expression was independent of change in α7nAChR expression. These findings suggest that HO-1 expression is unrelated to α7nAChR density and the increase in HO-1 expression likely contributes to α7nAChR activation-related neuroprotective effect in early-stage Huntington's disease.

Zinc L-carnosine suppresses inflammatory responses in lipopolysaccharide-induced RAW 264.7 murine macrophages cell line via activation of Nrf2/HO-1 signaling pathway

Context: Zinc L-carnosine (ZnC) is a chelate of Zn and L-carnosine and is used clinically in the treatment of peptic ulcer.Objective: In this study, we aim to investigate the involvement of heme oxygenase-1 (HO-1) in the anti-inflammatory effects of ZnC in lipopolysaccharide (LPS)-induced RAW 264.7 murine macrophages.Materials and methods: We used immunoblotting analysis to evaluate the involvement of HO-1 in the anti-inflammatory effects of ZnC and the signaling pathway involved was measured using Dual luciferase reporter assay.Results: Results from immunoblotting analysis demonstrated that pretreatment of cells with ZnC enhanced the expression of HO-1 in RAW 264.7 cells. Pretreatment of cells with HO-1 inhibitor (tin protoporphyrin IX dichloride) significantly attenuated the inhibitory effects of ZnC on nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) expression and NF-κB activation in LPS-induced RAW 264.7 cells, suggesting that HO-1 play an important role in the suppression of inflammatory responses induced by ZnC. Furthermore, results from co-immunoprecipitation of Nrf2 and Keap1 and dual luciferase reporter assay showed that pretreatment of ZnC was able to activate the Nrf2 signaling pathway. Treatment of cells with p38 inhibitor (SB203580), c-Jun N-terminal kinase inhibitor (SP600125), and MEK 1/2 inhibitor (U0126) did not significantly suppress the induction of HO-1 by ZnC. Moreover, our present findings suggest that the effects of ZnC on NO production, HO-1 expression, and Nrf2 activation were attributed to its Zn subcomponent, but not l-carnosine.Conclusion: Pretreatment with ZnC was able to activate Nrf2/HO-1 signaling pathway, thus suppressing the expression of inflammatory mediators, such as NO and iNOS in LPS-induced RAW 264.7 cells.

Involvement of Heme Oxygenase-1 in particulate matter-induced impairment of NO-dependent relaxation in rat intralobar pulmonary arteries

Particulate air pollution exerts deleterious effects on cardiovascular system. We previously described that exposure to urban particulate matter (SRM1648) impairs nitric oxide (NO, a major vasculoprotective factor) responsiveness in intrapulmonary arteries. As Heme Oxygenase-1 (HO-1) is induced by urban particles in some cell types and is known to alter NO-dependent signaling pathway, the objective was to characterize HO-1 involvement in SRM1648-induced impairment of NO-dependent relaxation in intrapulmonary arteries.Rat intrapulmonary artery rings were exposed or not to Co (III) Protoporphyrin IX Chloride (HO-1 inducer) or SRM1648 in the absence or presence of Cr (III) Mesoporphyrin IX Chloride (HO-1 activity inhibitor). NO-dependent relaxation was assessed with DEA-NOnoate (DEA-NO) on pre-contracted arteries. HO-1 and soluble guanylyl-cyclase (sGC) mRNA and protein expressions were assessed by qRT-PCR and Western blotting, respectively.SRM1648 or Co (III) Protoporphyrin IX Chloride exposure (24) impaired DEA-NO-dependent relaxation. The SRM-induced alteration of DEA-NO responsiveness was partially prevented by Cr (III) Mesoporphyrin IX Chloride. Co (III) Protoporphyrin IX Chloride induced HO-1 mRNA and protein expressions, whereas SRM1648 only induced HO-1 protein expression without affecting its mRNA level. Exposure to either SRM1648 or to Co (III) Protoporphyrin IX Chloride did not affect the expression levels of sGC.In conclusion, this study provides some evidence that impairment of NO signaling pathway in intrapulmonary arteries involves HO-1. Therefore it highlights the role of HO-1 in particulate matter-induced detrimental effects in pulmonary circulation.

Activation of Nrf2/HO-1signaling pathway involves the anti-inflammatory activity of magnolol in Porphyromonas gingivalis lipopolysaccharide-stimulated mouse RAW 264.7 macrophages

Magnolol isolated from Magnolia officinalis, a Chinese medical herb, exhibits an anti-inflammatory activity and a protective effect against periodontitis. The inflammation caused by lipopolysaccharide (LPS) from Porphyromonas gingivalis (P. gingivalis) has been considered a key inducer in the development of periodontitis. In this study, we investigated whether magnolol inhibits P. gingivalis LPS-evoked inflammatory responses in RAW 264.7 macrophages and the involvement of heme oxygenase-1 (HO-1). Magnolol significantly activated p38 MAPK, Nrf-2/HO-1 cascade and reactive oxygen species (ROS) formation. Notably, the Nrf-2 activation and HO-1 induction by magnolol were greatly diminished by blocking p38 MAPK activity and ROS production. Furthermore, in P. gingivalis LPS-stimulated macrophages, magnolol treatment remarkably inhibited the inflammatory responses evidenced by suppression of pro-inflammatory cytokine, prostaglandin E2, nitrite formation, and the expression of inducible nitric oxide synthase and cyclooxygenase-2, as well as NF-κB activation accompanied by a significant elevation of Nrf-2 nuclear translocation and HO-1 expression/activity. However, inhibiting HO-1 activity with tin protoporphyrin IX markedly reversed the anti-inflammatory effects of magnolol. Collectively, these findings provide a novel mechanism by which magnolol inhibits P. gingivalis LPS-induced inflammation in macrophages is at least partly mediated by HO-1 activation, and thereby promoting its clinical use in periodontitis.

Cepharanthine mitigates pro-inflammatory cytokine response in lung injury induced by hemorrhagic shock/resuscitation in rats

BackgroundCepharanthine possesses strong anti-inflammation capacity. We sought to clarify whether cepharanthine could mitigate pro-inflammatory cytokine production in acute lung injury induced by hemorrhagic shock/resuscitation (HS/RES). The involvement of heme oxygenase-1 (HO-1) was also investigated. MethodsMale Sprague Dawley rats were allocated to receive HS/RES, HS/RES plus iv cepharanthine or HS/RES plus cepharanthine plus the HO-1 activity inhibitor tin protoporphyrin (SnPP) and denoted as the HS/RES, HS/RES+CEP, and HS/RES+CEP+SnPP group, respectively. HS/RES was achieved by blood drawing to lower mean arterial pressure (40–45mmHg for 60min) followed by shed blood/saline mixtures re-infusion. The rats were monitored for another 5h before sacrifice. ResultsArterial blood gas, lung permeability and histologic assays (including histopathology, neutrophil infiltration, and lung water content) confirmed that HS/RES induced significant lung injury. Significant increases in pulmonary levels of tumor necrosis factor-α, interleukin-1β, interleukin-6, prostaglandin E2 and cyclooxygenase-2 confirmed that HS/RES induced a significant inflammatory response in the lungs. Cepharanthine significantly attenuated the pulmonary pro-inflammatory cytokine production and lung injury induced by HS/RES. However, the protective effects of cepharanthine were blocked by SnPP, the potent HO-1 activity inhibitor. ConclusionCepharanthine significantly mitigates pro-inflammatory cytokine response in acute lung injury induced by HS/RES in rats. The mechanism may involve the HO-1 pathway.

Involvement of heme oxygenase-1 in the attenuation of the cardioprotective effect of ischemic preconditioning in diabetic rat heart

Involvement of heme oxygenase-1 in the attenuation of the cardioprotective effect of ischemic preconditioning in diabetic rat heart

Involvement of Heme Oxygenase-1 in Orexin-A-induced Angiogenesis in Vascular Endothelial Cells.

The cytoprotective enzyme heme oxygenase-1 (HO-1) influences endothelial cell survival, proliferation, inflammatory response, and angiogenesis in response to various angiogenic stimuli. In this study, we investigate the involvement of HO-1 in the angiogenic activity of orexin-A. We showed that orexin-A stimulates expression and activity of HO-1 in human umbilical vein endothelial cells (HUVECs). Furthermore, we showed that inhibition of HO-1 by tin (Sn) protoporphryin-IX (SnPP) reduced orexin-A-induced angiogenesis in vivo and ex vivo. Orexin-A-stimulated endothelial tube formation and chemotactic activity were also blocked in SnPP-treated vascular endothelial cells. Orexin-A treatment increased the expression of nuclear factor erythroid-derived 2 related factor 2 (Nrf2), and antioxidant response element (ARE) luciferase activity, leading to induction of HO-1. Collectively, these findings indicate that HO-1 plays a role as an important mediator of orexin-A-induced angiogenesis, and provide new possibilities for therapeutic approaches in pathophysiological conditions associated with angiogenesis.

Involvement of heme oxygenase-1 in neuroprotection by sanguinarine against glutamate-triggered apoptosis in HT22 neuronal cells

Sanguinarine is a natural compound isolated from the roots of Macleaya cordata and M. microcarpa, has been reported to possess several biological activities such as anti-inflammatory and anti-oxidant effects. In the present study, we demonstrated that sanguinarine markedly induces the expression of HO-1 which leads to a neuroprotective response in mouse hippocampus-derived neuronal HT22 cells from apoptotic cell death induced by glutamate. Sanguinarine significantly attenuated the loss of mitochondrial function and membrane integrity associated with glutamate-induced neurotoxicity. Sanguinarine protected against glutamate-induced neurotoxicity through inhibition of HT22 cell apoptosis. JC-1 staining, which is a well-established measure of mitochondrial damage, was decreased after treatment with sanguinarine in glutamate-challenged HT22cells. In addition, sanguinarine diminished the intracellular accumulation of ROS and Ca2+. Sanguinarine also induced HO-1, NQO-1 expression via activation of Nrf2. Additionally, we found that si RNA mediated knock-down of Nrf2 or HO-1 significantly inhibited sanguinarine-induced neuroprotective response. These findings revealed the therapeutic potential of sanguinarine in preventing the neurodegenerative diseases.

Anti-Inflammatory Activity of Capsaicin and Dihydrocapsaicin through Heme Oxygenase-1 Induction in Raw264.7 Macrophages

Capsaicin (CAP) and dihydrocapsaicin (DHC) are major pungent components of hot peppers with various biological activities such as anticancer, anti-obesity and anti-inflammatory properties. We focused on the involvement of heme oxygenase-1 (HO-1) in the anti-inflammatory activity of CAP and DHC in lipopolysaccaride (LPS)-stimulated RAW264.7 macrophages. We demonstrated that both CAP and DHC inhibited nitric oxide (NO) production and inducible NO synthase protein and mRNA expression in LPS-stimulated RAW264.7 macrophages. In addition, both CAP and DHC increased HO-1 protein expression. The inhibition of NO production by treatment with CAP and DHC was attenuated by blocking HO-1 activity. This study provide evidence to support the important role of HO-1 in the anti-inflammatory activity of CAP and DHC. Practical Applications CAP and DHC are major pungent components of hot peppers. They have been subjected to extensive experimental and clinical investigations because of their various pharmacological and toxicological properties. In this study, the anti-inflammatory mechanism of CAP and DHC was evaluated in RAW264.7 macrophages. Our results revealed that CAP and DHC exert anti-inflammatory activities by activating HO-1. Also, these data provides further insights on the molecular mechanisms underlying the biological activities and pharmacological use of CAP and DHC.

Involvement of hemeoxygenase-1 in di(2-ethylhexyl) phthalate (DEHP)-induced apoptosis of Neuro-2a cells

A widely-used plasticizer di(2-ethylhexyl) phthalate (DEHP) is known to induce apoptosis in neurons, although the mechanisms responsible for DEHP-induced apoptosis is not well explored yet. We recently showed that exposure to DEHP increases the expression of hemeoxygenase (HO)-1, an oxidative stress related enzyme, in the mice brain. In this study, we investigated whether HO-1 is involved in DEHP-induced apoptosis using a mouse neuroblastoma cell line Neuro-2a, which forcibly express SCAT3, a fluorescent indicator of caspase-3 activity. The doses of DEHP at 1, 10 or 100 µM were used in the present study to mimic the level of human exposure to DEHP. Live image analysis of SCAT3-expressing Neuro-2a cells revealed that caspase-3 activity in the cells was significantly increased by DEHP at 100 µM but not 1 or 10 µM. We measured HO-1 mRNA level in Neuro-2a cells exposed to DEHP and found significant increase in HO-1 mRNA level by DEHP at 100 µM but not 1 or 10 µM. Live image analysis of SCAT3-expresisng Neuro-2a cells was further performed to determine the effects of HO-1 siRNA in DEHP-induced apoptosis via caspase-3 activation. We found that knockdown of HO-1 gene nullifies the effects of DEHP to activate caspase-3. These results suggest that HO-1 is involved in DEHP-induced apoptosis. Moreover, this study demonstrates that high-dose DEHP exposure induces caspase-3-dependent apoptosis, which is at least partially mediated by the up-regulation of HO-1 gene, in Neuro-2a cells.

Involvement of haem oxygenase-1 in hydrogen peroxide-induced lateral root formation in tomato

The objective of this study was to test whether haem oxygenase-1 (HO-1) is involved in hydrogen peroxide (H2O2)-induced lateral root (LR) formation. The results showed that 0.1 mM H2O2 mimicked the effects of the HO-1 inducer, haemin, on the up-regulation of tomato HO-1 (SlHO1) expression, increased carbon monoxide (CO) synthesis and LR formation. However, 1.0 mM H2O2 resulted in inhibitory responses. The above inducible or inhibitory responses elicited by 0.1 and 1.0 mM H2O2 were noticeably blocked or rescued by the HO-1 inhibitor zinc protoporphyrin IX (ZnPP) or haemin, and then separately reversed by CO or ZnPP. Further trials showed that haemin-induced responses were not altered by the H2O2 trap, dimethylthiourea (DMTU). When applied alone, DMTU not only decreased H2O2 contents but also inhibited SlHO1 expression and LR development. These responses were recovered by the application of haemin or CO. Molecular evidence revealed that H2O2-modulated expression of the target genes responsible for LR formation was blocked by ZnPP, but rescued by CO. Salinity-induced up-regulation of HO-1 expression and thereafter LR formation were also dependent on the H2O2 generation. Overall, these results demonstrated a possible role of HO-1 in the H2O2-induced tomato LR formation.

Therapeutic efficacy of naringin on cyclosporine (A) induced nephrotoxicity in rats: Involvement of hemeoxygenase-1

BackgroundClinically, chronic nephrotoxicity may lead to renal functional impairment and progress to end stage renal failure. The renoprotective effect of a flavonoid naringin(NG) against cyclosporineA(CsA)-induced nephrotoxicitywas investigated in this study. MethodsNephrotoxicity was induced in male albinoWistar rats by injecting 25mg/kg body weight of CsAfor a period of 21 days. CsA-induced rats were also cotreated with 40mg of NG/kg body weight, orally. ResultsAfter the experimental period, the levels of lipid peroxides (TBARS) and hydroxyl radical (OH.) were found to be elevated, whereas the levels of SOD, catalase, glutathione, vitamin C, E and Awere decreased in CsA-induced rats. NG co-treatment significantly decreased the levels of lipid peroxides and hydroxyl radicals and restored the levels of enzymic and non-enzymic antioxidants in renal tissues. Histological analysis revealed that CsA administration caused severe and widespread necrosis with dilatation of proximal tubules, vacuolization, tubular cell desquamation and intraluminal cast formation with massive infiltration of inflammatory cells. CsA-induced histopathological renal changes were minimal in animals which received NG treatment. The western blot and confocal microscopic expression of heme oxygenase-1 was restored by NG. In CsA-induced animals the expression was reduced compared to NG treated animals. ConclusionsThe present study reveals that NG can act as effective renoprotective drug against CsA-induced toxicity.