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Induction of heme oxygenase-1 by chamomile protects murine macrophages against oxidative stress.

ABSTRACT: Protection of cells from oxidative insult may be possible through direct scavenging of reactive oxygen species, or through stimulation of intracellular antioxidant defense mechanisms by induction of antioxidant gene expression. In this study we investigated the cytoprotective effect of chamomile and elucidated the underlying mechanisms.The cytoprotective effect of chamomile was examined on H(2)O(2)-induced cellular stress in RAW 264.7 murine macrophages.RAW 264.7 murine macrophages treated with chamomile were protected from cell death caused by H(2)O(2). Treatment with 50?M H(2)O(2) for 6h caused significant increase in cellular stress accompanied by cell death in RAW 264.7 macrophages. Pretreatment with chamomile at 10-20?g/mL for 16h followed by H(2)O(2) treatment protected the macrophages against cell death. Chamomile exposure significantly increased the expression of antioxidant enzymes viz. heme oxygenase-1 (HO-1), peroxiredoxin-1 (Prx-1), and thioredoxin-1 (Trx-1) in a dose-dependent manner, compared with their respective controls. Chamomile increased nuclear translocation of Nrf2 with increased phosphorylated Nrf2 levels, and binding to the antioxidant response element in the nucleus.These molecular findings for the first time provide insights into the mechanisms underlying the induction of phase 2 enzymes through the Keap1-Nrf2 signaling pathway by chamomile, and provide evidence that chamomile possesses antioxidant and cytoprotective properties.

SUBMITTER: Bhaskaran N

PROVIDER: S-EPMC3389181 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Induction of heme oxygenase-1 by chamomile protects murine macrophages against oxidative stress.

Bhaskaran Natarajan N Shukla Sanjeev S Kanwal Rajnee R Srivastava Janmejai K JK Gupta Sanjay S

Life sciences 20120605 25-26

<h4>Aims</h4>Protection of cells from oxidative insult may be possible through direct scavenging of reactive oxygen species, or through stimulation of intracellular antioxidant defense mechanisms by induction of antioxidant gene expression. In this study we investigated the cytoprotective effect of chamomile and elucidated the underlying mechanisms.<h4>Main methods</h4>The cytoprotective effect of chamomile was examined on H(2)O(2)-induced cellular stress in RAW 264.7 murine macrophages.<h4>Key ...[more]

PMID: 22683429

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Project description:Diabetic retinopathy is a leading cause of visual loss and blindness, characterized by microvascular dysfunction. Hyperglycemia is considered the major pathogenic factor for the development of diabetic retinopathy and is associated with increased oxidative/nitrosative stress in the retina. Since heme oxygenase-1 (HO-1) is an enzyme with antioxidant and protective properties, we investigated the potential protective role of HO-1 in retinal endothelial cells exposed to high glucose and oxidative/nitrosative stress conditions. Retinal endothelial cells were exposed to elevated glucose, nitric oxide (NO) and hydrogen peroxide (H(2)O(2)). Cell viability and apoptosis were assessed by MTT assay, Hoechst staining, TUNEL assay and Annexin V labeling. The production of reactive oxygen species (ROS) was detected by the oxidation of 2',7'-dichlorodihydrofluorescein diacetate. The content of HO-1 was assessed by immunobloting and immunofluorescence. HO activity was determined by bilirubin production. Long-term exposure (7 days) of retinal endothelial cells to elevated glucose decreased cell viability and had no effect on HO-1 content. However, a short-time exposure (24 h) to elevated glucose did not alter cell viability, but increased both the levels of intracellular ROS and HO-1 content. Moreover, the inhibition of HO with SnPPIX unmasked the toxic effect of high glucose and revealed the protection conferred by HO-1. Oxidative/nitrosative stress conditions increased cell death and HO-1 protein levels. These effects of elevated glucose and HO inhibition on cell death were confirmed in primary endothelial cells (HUVECs). When cells were exposed to oxidative/nitrosative stress conditions there was also an increase in retinal endothelial cell death and HO-1 content. The inhibition of HO enhanced ROS production and the toxic effect induced by exposure to H(2)O(2) and NOC-18 (NO donor). Overexpression of HO-1 prevented the toxic effect induced by H(2)O(2) and NOC-18. In conclusion, HO-1 exerts a protective effect in retinal endothelial cells exposed to hyperglycemic and oxidative/nitrosative stress conditions.

Project description:Objectives This study was focused on the role of indole acetic acid (IAA) in the defense against oxidative stress damage caused by drought in soybean plants and to elucidate whether heme oxygenase-1 (HO-1) and nitric oxide (NO) are involved in this mechanism. IAA is an auxin that participates in many plant processes including oxidative stress defense, but to the best of our knowledge no information is yet available about its possible action in drought stress. Methods To this end, soybean plants were treated with 8% polyethylene glycol (PEG) or 100 µM IAA. To evaluate the behavior of IAA, plants were pretreated with this compound previous to PEG addition. Lipid peroxidation levels (thiobarbituric acid reactive substances (TBARS)), glutathione (GSH) and ascorbate (AS) contents, catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (POD) activities were determined to evaluate oxidative damage. Results Drought treatment (8% PEG) caused a significant increase in TBARS levels as well as a marked decrease in the non-enzymatic (GSH and AS) and enzymatic (CAT, SOD, and POD) antioxidant defense systems. Pre-treatment with IAA prevented the alterations of stress parameters caused by drought, while treatment with IAA alone did not produce changes in TBARS levels, or GSH and AS contents. Moreover, the activities of the classical enzymes involved in the enzymatic defense system (SOD, CAT, and POD) remained similar to control values. Furthermore, this hormone could enhance HO-1 activity (75% with respect to controls), and this increase was positively correlated with protein content as well as gene expression. The direct participation of HO-1 as an antioxidant enzyme was established by performing experiments in the presence of Zn-protoporphyrin IX, a well-known irreversible inhibitor of this enzyme. It was also demonstrated that HO-1 is modulated by NO, as shown by experiments performed in the presence of an NO donor (sodium nitroprusside), an NO scavenger (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), or an NO synthesis inhibitor (N-nitro-l-arginine methyl ester, NAME). Discussion It is concluded that IAA is responsible, at least in part, for the protection against oxidative stress caused by drought in soybean plants through the modulation of NO levels which, in turn, enhances HO-1 synthesis and activity.

Project description:Heme oxygenase (HO), in conjunction with biliverdin reductase, degrades heme to carbon monoxide, ferrous iron and bilirubin (BR); the latter is a potent antioxidant. The induced isoform HO-1 has evoked intense research interest, especially because it manifests anti-inflammatory and anti-apoptotic effects relieving acute cell stress. The mechanisms by which HO mediates the described effects are not completely clear. However, the degradation of heme, a strong pro-oxidant, and the generation of BR are considered to play key roles. The aim of this study was to determine the effects of BR on vital functions of hepatocytes focusing on mitochondria and the endoplasmic reticulum (ER). The affinity of BR to proteins is a known challenge for its exact quantification. We consider two major consequences of this affinity, namely possible analytical errors in the determination of HO activity, and biological effects of BR due to direct interaction with protein function. In order to overcome analytical bias we applied a polynomial correction accounting for the loss of BR due to its adsorption to proteins. To identify potential intracellular targets of BR we used an in vitro approach involving hepatocytes and isolated mitochondria. After verification that the hepatocytes possess HO activity at a similar level as liver tissue by using our improved post-extraction spectroscopic assay, we elucidated the effects of increased HO activity and the formed BR on mitochondrial function and the ER stress response. Our data show that BR may compromise cellular metabolism and proliferation via induction of ER stress. ER and mitochondria respond differently to elevated levels of BR and HO-activity. Mitochondria are susceptible to hemin, but active HO protects them against hemin-induced toxicity. BR at slightly elevated levels induces a stress response at the ER, resulting in a decreased proliferative and metabolic activity of hepatocytes. However, the proteins that are targeted by BR still have to be identified.

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Induction of heme oxygenase-1 by chamomile protects murine macrophages against oxidative stress.

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Induction of heme oxygenase-1 by chamomile protects murine macrophages against oxidative stress.

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