- About this Journal ·
- Abstracting and Indexing ·
- Advance Access ·
- Aims and Scope ·
- Annual Issues ·
- Article Processing Charges ·
- Articles in Press ·
- Author Guidelines ·
- Bibliographic Information ·
- Citations to this Journal ·
- Contact Information ·
- Editorial Board ·
- Editorial Workflow ·
- Free eTOC Alerts ·
- Publication Ethics ·
- Reviewers Acknowledgment ·
- Submit a Manuscript ·
- Subscription Information ·
- Table of Contents
Oxidative Medicine and Cellular Longevity
Volume 2013 (2013), Article ID 690545, 11 pages
Regulation of NF-B-Induced Inflammatory Signaling by Lipid Peroxidation-Derived Aldehydes
Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
Received 21 February 2013; Accepted 22 March 2013
Academic Editor: Sharad S. Singhal
Copyright © 2013 Umesh C. S. Yadav and Kota V. Ramana. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Oxidative stress plays a critical role in the pathophysiology of a wide range of diseases including cancer. This view has broadened significantly with the recent discoveries that reactive oxygen species initiated lipid peroxidation leads to the formation of potentially toxic lipid aldehyde species such as 4-hydroxy-trans-2-nonenal (HNE), acrolein, and malondialdehyde which activate various signaling intermediates that regulate cellular activity and dysfunction via a process called redox signaling. The lipid aldehyde species formed during synchronized enzymatic pathways result in the posttranslational modification of proteins and DNA leading to cytotoxicity and genotoxicty. Among the lipid aldehyde species, HNE has been widely accepted as a most toxic and abundant lipid aldehyde generated during lipid peroxidation. HNE and its glutathione conjugates have been shown to regulate redox-sensitive transcription factors such as NF-B and AP-1 via signaling through various protein kinase cascades. Activation of redox-sensitive transcription factors and their nuclear localization leads to transcriptional induction of several genes responsible for cell survival, differentiation, and death. In this review, we describe the mechanisms by which the lipid aldehydes transduce activation of NF-B signaling pathways that may help to develop therapeutic strategies for the prevention of a number of inflammatory diseases.
Lipid peroxidation-derived aldehydes (LDAs) have been implicated in a number of oxidative stress-induced inflammatory pathologies such as diabetes, metabolic syndrome, vascular and neural degeneration, liver and kidney toxicity, cancer, retinopathy of prematurity, aging, and ischemia [1–12]. LDAs such as malondialdehyde (MDA), 4-hydroxy-2-nonenal (HNE), and acrolein are generated upon degradation of lipid peroxides subsequent to free radical-induced peroxidation of membrane lipids, particularly the polyunsaturated fatty acids, in the biological membranes [13, 14]. Arachidonic acid present in the biological membranes is predominantly susceptible to free radical attacks due to the presence of unsaturated bonds and is the primary source of LDAs. LDAs are relatively more stable as compared to free radicals such as oxygen and hydroxyl free radicals and act as highly reactive electrophilic molecules . Quantitatively, while HNE and MDA are the most abundant aldehydes formed subsequent to lipid peroxidation, acrolein is the most reactive one. However, LDAs in general, have a tendency to react readily with the nucleophiles including thiols and amines containing cellular macromolecules such as proteins, and nucleic acids leading to cellular damage and accumulation of chemically altered macromolecules [15, 16]. In various disease states conjugates of LDAs with proteins and nucleic acids have been identified; for example, HNE-protein adducts were detected in mitotic, necrotic, and apoptotic cells in brain tumor tissues . LDAs can act as toxic secondary messengers to propagate redox signals leading to cellular and tissue injury [18–20].
HNE generated from the peroxidation of arachidonic acid is highly toxic and the most abundant LDA in the living tissue reaching a reported concentration of up to 10 nanomol/g tissue . Its in-situ concentration plays a key role in the cell growth, death, and differentiation. HNE has been shown to exert marked biological effects by affecting and altering cellular signaling events, modifying and damaging protein and DNA, eventually leading to cytotoxicity and pathogenesis [18, 19]. Similar effects have been reported for acrolein as well [21–23]. In this review, we have discussed the mechanism of production of LDAs and their roles in regulating the inflammatory signals that activate redox-sensitive transcription factors such as NF-κB.
2. Oxidative Stress and Lipid Peroxidation
In aerobes, varieties of highly reactive chemical entities are formed as the by-product of the oxygen utilization which is collectively termed as reactive oxygen species (ROS) [24, 25]. The ROS include superoxide anion , hydroxy radical (OH·), nitric oxide radical (NO·), and their by-products (e.g., hydrogen peroxide, H2O2). A constant flux of ROS caused by acute or chronic inflammatory diseases or environmental stresses leads to a state of moderately increased levels of intracellular ROS resulting in a condition referred to as oxidative stress . The eukaryotic cells are evolutionarily evolved to modulate the oxidant levels in a highly efficient manner by maintaining sufficient antioxidant levels, induction of new gene expression and protein modification, and tightly regulating their redox status within a narrow range . However, in the event of persistent exposure to the oxidants and other toxic agents, excessive ROS are produced that are capable of causing oxidative damage to biomacromolecules such as peroxidation of membrane lipids, oxidation of amino acid side chains (especially cysteine), formation of protein-protein cross-links, oxidation of polypeptide backbones resulting in protein fragmentation, DNA damage, and DNA strand breaks [28, 29]. Out of all these events, the formation of lipid peroxidation products is highly damaging because it leads to widespread free radical reactions besides compromising the membrane integrity leading to loss of cell function and eventually results in severe cytotoxicity that may either lead to uncontrolled cell growth (neoplasia) or cell death (apoptosis) [30, 31].
The process of lipid peroxidation includes several chemical reactions or steps such as initiation, propagation, and termination (Figure 1) . The first step of lipid peroxidation that is, initiation, includes hydrogen atom abstraction by free radicals such as hydroxyl (·OH), alkoxyl (RO·), peroxyl (ROO·), and . The initial reaction of ·OH with polyunsaturated fatty acids produces a lipid radical (L·), which in turn reacts with the molecular oxygen to form a lipid peroxyl radical (LOO·) in the propagation reaction. The LOO· species then acquire a hydrogen atom from the neighboring fatty acid molecule and produce a lipid hydroperoxide (LOOH) and simultaneously generate a second lipid radical . The LOOH can further be cleaved by reduced metals, such as Fe++, forming a lipid alkoxyl radical (LO·). In addition, LOOH may also break down into the reactive aldehyde products or LDAs including MDA, HNE, ONE, 4-HHE, and acrolein in the presence of reduced metals or ascorbate [13, 33, 34]. A chain reaction sets in which both alkoxyl and peroxyl radicals stimulate lipid peroxidation by abstracting additional hydrogen atoms from neighboring lipid molecules [33–35]. This results in the disruption of major chunk of cell membrane lipids that disturbs the assembly of cell membrane causing alterations in membrane fluidity and permeability, alterations of ion transport, and suppression of metabolic processes . The final and third step is the termination which involves the formation of a hydroperoxide which is achieved by reaction of a peroxyl radical with α-tocopherol, a lipophilic chain-breaking molecule found in the cell membrane. Termination could also be achieved when a lipid radical (L·) reacts with lipid peroxide (LOO·) or when two peroxide molecules combine together and result in nonreactive species LOOL or hydroxylated derivative (LOH), respectively, which are relatively stable. Some of the lipid peroxides could also react with the membrane proteins that result in the termination [37, 38]. The propagation reaction is self-sustaining and continues unabated until the substrate is consumed or the termination reaction sets in by antioxidants or free radical quenchers . Thus, being a self-sustaining process, lipid peroxidation amplifies the effects of the original free radical and results in extensive tissue damage.
Lipid peroxidation, an indicator of oxidative stress in cells and tissues, is a well-defined mechanism of cell injury. Peroxidation of membrane lipids has been shown to generate toxic and unstable biomolecules such as reactive carbonyl compounds including LDAs. These highly reactive electrophiles readily react with cellular proteins and nucleic acids, and also activate signaling cascade molecules and activate transcription factors thus causing inflammation (Figure 2). The cells have elaborate mechanisms to handle the excessive levels of LDAs which include enzymes that detoxify the LDA by reducing them to respective alcohols, for example, aldose reductase (AR) and aldehyde reductase or by oxidizing them to acids, for example, aldehyde dehydrogenase. Most of the unsaturated LDAs such as HNE and acrolein are also metabolized through forming GS-LDAs. Some of the glutathione-S-transferase (GST) isozymes such as human GSTA4-4 and GST5-8 have been shown to significantly catalyze the conjugation of HNE. Several studies indicate that regulation of enzymatic activity of GSTs could modulate the cytotoxicity associated with the HNE [39–41]. Further, LDAs also readily react with cellular glutathione (GSH) forming GS-LDA conjugates which further get reduced into GS-lipid alcohols and transported out of the cells. Recently, our laboratory has extensively presented evidence that AR-catalyzed GS-LDAs could mediate the activation of redox-sensitive transcription factors.
3. NF-κB and Cell Signaling
NF-κB is a family of transcription factors that regulate expression of numerous genes and play important roles in immune and stress responses, inflammation, and apoptosis [42–45]. There are five known proteins which come together as subunits to constitute the transcription factor NF-κB. These are subunits p50 (derived from p105), p52 (derived from p100), p65 (RelA), c-Rel, and RelB. These subunits, ubiquitously expressed in mammalian cells and highly conserved across the species, can either form homodimer or heterodimer to form biologically active molecule of NF-κB, which translocates to the nucleus upon phosphorylation and transcribes various genes . Activation of NF-κB via canonical or noncanonical pathways is an important mechanism to regulate the body’s immune and inflammatory responses . Various pathogens, oxidants, cytokines, chemokines, and growth factors either via specific receptors or general oxidative stress induce the molecular signals that eventually lead to activation of a redox-sensitive transcription factor NF-κB . Once activated either via canonical or noncanonical pathway, NF-κB enters nucleus where it binds to the kB DNA binding sequence and transcribes various genes for cytokines, chemokines, and other inflammatory markers. The expression of a large number of genes involved in apoptosis, cell growth, survival, differentiation, and immune response is regulated by NF-κB, which is associated with an array of diseases such as autoimmune, cancer, and inflammatory diseases.
4. Lipid Aldehydes in NF-κB Mediated Cell Signaling
Increasing evidences suggest that aldehyde molecules generated endogenously during ROS-induced process of lipid peroxidation are involved in most of the pathophysiological effects associated with oxidative stress in cells and tissues [49, 50]. Though previously held view implied that lipid peroxidation products only elicit damage, more recently evolved paradigm suggests that their impact could be more varied and dependent upon factors including the species, concentration and the protein targets involved [51–53]. Increasing number of studies now implicate LDAs in regulating oxidant-induced cellular signaling [54–56]. The lipid aldehydes regulate cellular functions by interacting with the specific proteins covalently and non-covalently [57–59]. For example, protein adducts are formed through the reaction of lipid aldehydes with nucleophilic protein constituents, including amino acid residues such as cysteine, lysine, and histidine, resulting in Schiff base formation [60, 61]. Michael addition is another mechanism of protein adduction, where thiolate groups of cysteine residues react with electrophilic carbons present in α-β unsaturated carbonyls. The most simple oxidation products containing this reactive group, resulting from β-scission, include 4-HNE and acrolein. Please refer to few reviews available on the covalent reactivity of α-β unsaturated carbonyls with cellular biomolecules [57–61] for detailed information.
LDAs have been shown to regulate various signaling pathways initiated by cytokines, chemokines, and growth factors. HNE has been shown to regulate many PKC isozymes depending upon its in situ concentration. For example, in rat hepatocytes low concentrations of HNE (0.1–1 uM) activate PKC beta1 and beta2 isozymes while higher concentrations of HNE (1–10 uM) inhibit PKC beta isozymes . Further, PKC delta activity was inhibited by low concentrations of HNE (0.1 uM) and increased by high concentration of HNE (>1 uM; ). Although it is not clear how PKC isozymes are differentially regulated by HNE, it is possible that HNE could target upstream signals of PKC such as PLC and DAG which in turn may activate PKC isozymes. In addition to PKC, HNE can also regulate other kinases such as MAPK, ERK, and JNK indirectly by activating upstream kinases or directly by interacting with kinase active domains. Parola et al.  indicated that HNE could directly form conjugate with JNK which is responsible for histone modification and subsequent nuclear translocation. On the other hand, Song et al.  reported that HNE could activate JNK via activating an upstream kinase called stress-activated protein kinase kinase-1 (SPKK1). Similarly, HNE activates ERK via activating MEK1/2 and P38MAPK via activating MKK3/6 [66, 67]. However, it is not clear how HNE activates upstream kinases of ERK and MAPK. HNE could also activate receptor tyrosine kinases such as EGFR and PDGFR through direct conjugation .
The cell signaling pathways activated by LDAs include noncovalent mechanisms that involve binding to a protein receptor and covalent mechanisms that modify protein kinases directly. The direct interaction of LDAs with protein kinases such as SRC and PLC could change cellular calcium signaling and alter in-situ cation mobilization leading to activation of the caspases involved in cell death. Vatsyayan et al.  have shown that HNE besides being cytotoxic, at lower doses it triggers phosphorylation of epidermal growth factor receptor (EGFR) and activation of its downstream signaling components ERK1/2 and AKT which are known to be involved in cell proliferation. Similarly, Chaudhary et al.  concluded that HNE could evoke signaling for defense mechanisms to self-regulate its toxicity and simultaneously may affect multiple signaling pathways through its interactions with membrane receptors and transcription factors/repressors . Dwivedi et al.  suggested that HNE has concentration-dependent opposing effects to cell death and growth. This report indicates that constitutive levels of HNE are needed for normal cell functions and low levels of HNE promote proliferative machinery while high levels promote apoptotic signaling. Further, they suggested that HNE can modulate ligand-independent signaling by membrane receptors such as EGFR or Fas (CD95) and may act as a sensor of external stimuli for eliciting stress-response, suggesting a key role of HNE in cellular signaling . Furthermore, our laboratory has presented numerous evidences [71–73] that GS-LDAs when enzymatically reduced by AR, become important secondary messengers to activate signaling molecules that eventually leads to activation of NF-κB via yet unknown mechanism (Figure 3). The regulation of NF-κB activation is the key for LDAs to modulate various inflammatory pathologies. Since NF-κB transcribes various proinflammatory cytokines, growth factors, cell survival proteins, structural proteins, and apoptotic proteins, regulation of intracellular concentrations of LDAs could be novel strategy to prevent inflammatory complications. Indeed, recent studies indicate that enzymes that regulate LDAs generation or participate in their metabolism could actually prevent pathological effects of LDA-induced inflammatory complications [2–5, 73].
5. Activation of NF-κB under Oxidative Stress
Increased oxidative stress is a hallmark of inflammatory diseases such as those caused by infections, xenobiotics, environmental pollutants, and those of autoimmune etiology, and ROS is an essential mediator of intracellular signaling under a variety of conditions [74–79]. Several lines of evidence suggest that ROS mediates the activation of redox-sensitive transcription factors such as NF-κB and AP1, which in turn stimulate the expression of an array of inflammatory cytokines and chemokines genes [80, 81]. These evidences largely suggest the use of a variety of antioxidants that inhibit NF-κB activation and also antioxidant enzymes which are overexpressed as a counter mechanism to bring down the NF-κB activation. Excessive and unrestrained production of inflammatory mediators causes cytotoxicity in an autocrine and paracrine manner. Among various redox-sensitive transcription factors such as NF-κB, AP1, CREB, ERF2, NFAT, and ATF2 that are activated by increased ROS levels, NF-κB has been extensively studied and is implicated in many oxidative stress-induced inflammatory diseases [45–49]. Activation of NF-κB under oxidative stress has been noticed in a number of inflammatory complications. However, how exactly ROS activates various protein kinases upstream to NF-κB is not known clearly. In the preceding section, we presented evidence that suggests that ROS-generated HNE and other LDAs may directly or indirectly activate upstream kinases including tyrosine receptor kinases [6, 68].
We and others have also presented many evidences which implicate ROS-induced lipid peroxidation products such as lipid aldehydes in the activation of signaling cascade that eventually activates NF-κB [70, 73, 82, 83]. Indeed, ROS-induced lipid peroxidation has been proposed to be major contributor in the pathophysiology of many inflammatory disorders. HNE, generated by a number of oxidative stress conditions inducing etiologies including bacterial infection, xenobiotics, environmental pollutants, and autoimmune disorders, is one of the highly abundant and toxic lipid aldehydes . Acrolein is another highly reactive species generated both exo- and endogenously. Depending upon their respective concentrations both HNE and acrolein elicit phenotypically varied outcomes. Both are known to activate various upstream kinases including MAPK and PKC [71, 82, 85–89], thus enzymes that either regulate or metabolize HNE could be mediators of oxidative stress signals. Modification of multiple cytoskeletal proteins and the activation of MAPKs and ROS-sensitive transcription factors by HNE metabolizing enzymes have been demonstrated by various investigators [71, 82]. Further, growth factors and cytokine-induced increased generation of ROS could be an essential step for cell growth because overexpression of antioxidants such as catalase and super oxide dismutase (SOD) or treatment with antioxidants such as N-acetylcysteine (NAC) are known to diminish growth factor and cytokine-stimulated cell growth or death [90, 91]. Many studies have indeed indicated that ROS themselves can act as toxic messengers that activate NF-κB and affect the cellular functions of growth factors, cytokines and other molecules [92, 93]. These evidences clearly indicate that various stimulants and oxidants activate redox-sensitive transcription factors including NF-κB by generating ROS which in turn generate other secondary messengers such as lipid aldehydes that phosphorylate upstream signaling kinases.
6. Modulation of Oxidative Stress and Lipid Aldehydes Signals by Antioxidants
In oxidative stress-induced inflammatory diseases, antioxidant status of the tissues undergoes severe alteration leaving the cells overexposed to oxidative free radicals. The lipid peroxidation caused by increased ROS continues unabated leading to generation of further more free radicals and in this way a vicious cycle continues which results in the establishment and progression of the disease . The cells are endowed with antioxidant system which includes (a) SOD that catalyzes the breakdown of the superoxide anion into oxygen and hydrogen peroxide; (b) catalase, which catalyzes the conversion of hydrogen peroxide to water and oxygen, and (c) peroxiredoxin, which catalyzes the reduction of hydrogen peroxide, organic hydroperoxides, and peroxynitrate to tackle oxidative bouts [95, 96]. In addition, the cells also contain glutathione system which includes glutathione, glutathione reductase, glutathione peroxidases, and glutathione S-transferases, which maintains redox balance and protect from oxidative challenges [97, 98]. However, in the overwhelming oxidative stress these mechanisms become ineffective and cellular homeostasis disrupts . Many investigators have demonstrated that supplementation of antioxidants in the experimental animal models of oxidative stress-generated inflammatory pathologies successfully blocks the inflammatory changes [98–100]. Many antioxidants that inhibit oxidative stress signaling pathways are known to be effective in halting the inflammation in experimental animal models. For example, Vitamin C and E, N-acetylcysteine (NAC), Lipoic acid, GSH, carotenoids and flavonoids from plants, and melatonins, have been shown to be effective in experimental models of many diseases including cardiovascular, neurodegenerative, infection, diabetic complications, autoimmune, and allergic complications. A number of antioxidants have undergone clinical trials [101–107] to prevent disease pathologies including cardiovascular and cancer. These antioxidants however have not been successfully translated for the clinical use because at the clinical doses they become prooxidants and result in serious side effects. This restricts the use of antioxidants as therapeutic drugs and leaves them as prophylactic or preventive drugs only. In this scenario, a new drug which can be both antioxidative as well as anti-inflammatory that could regulate both ROS, and LDAs-induced signals could be a better approach to prevent inflammatory complications. Our results from the use of AR inhibitors in different preclinical models indicate that AR inhibitors such as fidarestat could be such a drug that can be used in the amelioration of inflammatory diseases including cardiovascular, sepsis, infection and autoimmune-induced uveitis, allergic asthma, cancer and metastasis, and angiogenesis [73, 108]. These encouraging observations have helped us to develop a highly specific and potent AR inhibitor, fidarestat, which has been tested in the phase-iii clinical studies for diabetic neuropathy and found to be safe for human use, as a potential antioxidative, anti-inflammatory, antiangiogenic, antimitogenic, and chemopreventive drug for preventing inflammatory diseases such as allergic asthma, colon cancer, and uveitis.
7. Role of AR in Mediation of Lipid Aldehydes Signals
It is well known that AR is overexpressed under oxidative stress initiated by various cytokines, growth factors, bacterial endotoxins such as lipopolysaccharides (LPS), and high glucose. Overexpression of AR increases the turnover of ROS-generated LDAs [73, 108]. The LDAs readily react with cellular GSH and form GSH-LDA conjugates which are excellent AR substrates [109, 110]. Since ROS is known to mediate and regulate intracellular signaling under diverse conditions, some of the effects of ROS can be mediated by ROS-derived LDAs and their GSH conjugates. We have systematically investigated the involvement of lipid aldehydes and their GSH conjugates in the mediation of signaling cascades that play important role in the pathophysiology of a number of diseases. The results from our studies indicate that reduction of LDAs and their GSH conjugates by AR is essential for transduction of cytotoxic signals [82–84]. This was firmly confirmed by various evidences including that AR has poor affinity for glucose (Km of 50–100 mM), and in normal conditions only a small percentage (3%) of glucose is metabolized by AR . Further, the kinetic and structural properties of AR are unlike those of other glucose-metabolizing enzymes [112, 113]. The low Km for catalysis of carbohydrate reduction is probably due to high hydrophobicity of the substrate binding domain of AR which essentially prevents efficient reduction of glucose by AR and suggests that hydrophobic aldehydes could likely be the preferred substrates. Indeed, we have unequivocally demonstrated that AR efficiently catalyzes lipid aldehydes and their GSH conjugates [109, 110]. For example, recombinant human AR has been shown to catalyze the reduction of a large series of saturated and unsaturated aldehydes with 1000-fold higher efficiency when compared to glucose [109–112]. Medium- to long-chain (C-6 to C-18) aldehydes, which are generated during lipid peroxidation, are most efficiently catalyzed by AR . In particular, the catalytic site of AR has more affinity towards GS-aldehyde conjugates than parent aldehydes. This is confirmed by site-directed mutagenesis studies showing that AR active site has amino acid residues which efficiently bind with glutathione moiety . Further, molecular modeling of AR-GSH analog crystal structure confirmed that AR has a specific GS-aldehyde binding site at its catalytic site . Thus, these observations firmly support that physiological role of AR could be the reduction of LDAs besides glucose metabolism in polyol pathway.
Since LDAs are known to modulate the cellular function by regulating the oxidative stress signals mediated by NF-κB and AP1 [114–118], we postulated that AR regulates cellular functions by modulating oxidative stress signals. Our claim is supported by the studies demonstrating that AR inhibition prevents HNE-, growth factor-, and cytokine-induced cytotoxicity in a variety of cultured cells [73, 108]. Further, our studies also demonstrated that inhibition of AR prevents endotoxin-, allergen-, cytokine-, and growth factor-induced activation of NF-κB signals (Figure 3). In all these conditions, increased ROS levels, lipid peroxidation, and subsequent formation of lipid aldehydes play a major role in disrupting the cellular homeostasis. Thus, our observations present a basis for the novel role of AR in the pathophysiology of various inflammatory disease processes mediated by LDAs.
Besides the novel role implicating AR in mediating signaling of the ROS-derived lipid aldehydes in inflammatory pathologies, the exact role of AR in the mediation of cellular signaling is not yet clear. How AR-catalyzed product of GS-LDAs activates PKC and PLC isozymes still needs to be investigated. Nevertheless, we have shown that AR-catalyzed reduced product of GS-DHN activates various kinases including PLC, PKC, and PI3K in cultured cells. Activation of these kinases eventually results in the activation of redox-sensitive transcription factors which transcribe various inflammatory genes responsible for disease progression. The involvement of AR-catalyzed reaction products in eliciting oxidative stress-induced cytotoxicity and inflammation is more obvious given the fact that inhibition of AR prevents the increased synthesis of inflammatory cytokines and chemokines by various oxidant stimuli such as LPS, cytokines, growth factors, and high glucose. This is further substantiated by our demonstration that HNE, GS-HNE, and AR-catalyzed reduced product of GS-LDAs, that is, GS-DHN promote, VSMC growth in vitro . AR inhibition by pharmacological inhibitors or ablation by siRNA prevents HNE- and GS-HNE-induced VSMC proliferation but has no effect on the GS-DHN-induced changes. These studies thus suggest that the reduced forms of lipid-aldehyde glutathione conjugates (such as GS-DHN) could be involved in the oxidative stress-induced inflammatory signaling. Further studies are required to investigate the exact mechanism of GS-DHN-induced activation of upstream kinases that results in transcription of inflammatory genes. Nevertheless, our observations have opened up a new area of research in understanding the role of AR in the mediation of oxidative stress signaling in a number of inflammatory diseases.
8. Current and Future Developments
Oxidative stress-induced generation of lipid aldehydes has been observed in many inflammatory complications including cardiovascular disorders, bacterial sepsis, cancer, and asthma, which present enormous clinical challenges worldwide. Many researchers have presented the immense importance of this aspect of pathophysiology, and therefore there is an urgent need for development of new therapeutic strategies targeting the intervention in lipid aldehyde-mediated inflammatory signals in these diseases. However, a more precise elucidation of lipid aldehyde-induced inflammatory signaling is crucial for understanding the pathophysiology of multiple diseases including infections, atherosclerosis, autoimmune, and cancer. Based on these elucidations, a better therapeutic intervention could be developed to contain the inflammatory responses in patients. Our extensive research during recent years has identified that oxidative stress-induced LDAs and their GS-conjugates catalyzed by AR play a major role in the mediation of NF-κB-induced inflammatory signals via PLC/PKC/IKK/MAPK pathways. We have demonstrated that in experimental animal models, inhibition of GS-LDA metabolizing enzymes, specifically AR, prevents inflammatory diseases such as uveitis, sepsis, colon cancer, atherosclerosis, and allergic asthma. These results have delineated a novel mechanism regulating inflammation and have laid foundation for future studies that could result in clinical application of AR inhibitors. Further, a better understanding of the role of AR-catalyzed LDAs and their GSH-conjugates in the signalosome and inflammasome signaling pathways will better reveal underlying pathophysiological events in various inflammatory diseases.
|ROS:||Reactive oxygen species|
|LDAs:||Lipid peroxidation-derived aldehydes|
|NADPH:||Reduced nicotinamide adenine dinucleotide phosphate|
|PKC:||Protein kinase C|
|MAPK:||Mitogen-activated protein kinase|
|NF-κB:||Nuclear factor kappa B|
|AP-1:||Activator protein 1|
|CREB:||cAMP response element-binding protein|
|VSMC:||Vascular smooth muscle cells|
|AMD:||Age-related macular degeneration|
|EGFR:||Epidermal growth factor receptor.|
- N. J. Pillon, M. L. Croze, R. E. Vella, L. Soulère, M. Lagarde, and C. O. Soulage, “The lipid peroxidation by-product 4-hydroxy-2-nonenal (4-HNE) induces insulin resistance in skeletal muscle through both carbonyl and oxidative stress,” Endocrinology, vol. 153, no. 5, pp. 2099–2111, 2012.
- M. P. Mattson, “Roles of the lipid peroxidation product 4-hydroxynonenal in obesity, the metabolic syndrome, and associated vascular and neurodegenerative disorders,” Experimental Gerontology, vol. 44, no. 10, pp. 625–633, 2009.
- C. S. Kang, H. W. Kim, B. K. Kim et al., “Hepatotoxicity and nephrotoxicity produced by 4-hydroxy-2-nonenal (4-HNE) following 4-week oral administration to sprague-dawley rats,” Journal of Toxicology and Environmental Health A, vol. 74, no. 12, pp. 779–789, 2011.
- P. Karihtala, S. Kauppila, U. Puistola, and A. Jukkola-Vuorinen, “Divergent behaviour of oxidative stress markers 8-hydroxydeoxyguanosine (8-OHdG) and 4-hydroxy-2-nonenal (HNE) in breast carcinogenesis,” Histopathology, vol. 58, no. 6, pp. 854–862, 2011.
- K. Uno, K. Kato, G. Kusaka, N. Asano, K. Iijima, and T. Shimosegawa, “The balance between 4-hydroxynonenal and intrinsic glutathione/glutathione S-transferase A4 system may be critical for the epidermal growth factor receptor phosphorylation of human esophageal squamous cell carcinomas,” Molecular Carcinogenesis, vol. 50, no. 10, pp. 781–790, 2011.
- R. Vatsyayan, P. Chaudhary, A. Sharma et al., “Role of 4-hydroxynonenal in epidermal growth factor receptor-mediated signaling in retinal pigment epithelial cells,” Experimental Eye Research, vol. 92, no. 2, pp. 147–154, 2011.
- S. Qin and G. A. Rodrigues, “Differential roles of AMPKα1 and AMPKα2 in regulating 4-HNE-induced RPE cell death and permeability,” Experimental Eye Research, vol. 91, no. 6, pp. 818–824, 2010.
- M. Singh, T. N. Dang, M. Arseneault, and C. Ramassamy, “Role of by-products of lipid oxidation in Alzheimer's disease brain: a focus on acrolein,” Journal of Alzheimer's Disease, vol. 21, no. 3, pp. 741–756, 2010.
- D. A. Butterfield, M. L. Bader Lange, and R. Sultana, “Involvements of the lipid peroxidation product, HNE, in the pathogenesis and progression of Alzheimer's disease,” Biochimica et Biophysica Acta, vol. 1801, no. 8, pp. 924–929, 2010.
- W. Völkel, T. Sicilia, A. Pähler et al., “Increased brain levels of 4-hydroxy-2-nonenal glutathione conjugates in severe Alzheimer's disease,” Neurochemistry International, vol. 48, no. 8, pp. 679–686, 2006.
- M. Fukai, T. Hayashi, R. Yokota et al., “Lipid peroxidation during ischemia depends on ischemia time in warm ischemia and reperfusion of rat liver,” Free Radical Biology and Medicine, vol. 38, no. 10, pp. 1372–1381, 2005.
- E. McCracken, D. I. Graham, M. Nilsen, J. Stewart, J. A. R. Nicoll, and K. Horsburgh, “4-hydroxynonenal immunoreactivity is increased in human hippocampus after global ischemia,” Brain Pathology, vol. 11, no. 4, pp. 414–421, 2001.
- H. Esterbauer, R. J. Schaur, and H. Zollner, “Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes,” Free Radical Biology and Medicine, vol. 11, no. 1, pp. 81–128, 1991.
- A. Loidl-Stahlhofen, K. Hannemann, and G. Spiteller, “Generation of α-hydroxyaldehydic compounds in the course of lipid peroxidation,” Biochimica et Biophysica Acta, vol. 1213, no. 2, pp. 140–148, 1994.
- R. M. LoPachin, T. Gavin, D. R. Petersen, and D. S. Barber, “Molecular mechanisms of 4-hydroxy-2-nonenal and acrolein toxicity: nucleophilic targets and adduct formation,” Chemical Research in Toxicology, vol. 22, no. 9, pp. 1499–1508, 2009.
- A. T. Jacobs and L. J. Marnett, “Systems analysis of protein modification and cellular responses induced by electrophile stress,” Accounts of Chemical Research, vol. 43, no. 5, pp. 673–683, 2010.
- G. Juric-Sekhar, K. Zarkovic, G. Waeg, A. Cipak, and N. Zarkovic, “Distribution of 4-hydroxynonenal-protein conjugates as a marker of lipid peroxidation and parameter of malignancy in astrocytic and ependymal tumors of the brain,” Tumori, vol. 95, no. 6, pp. 762–768, 2009.
- U. C. S. Yadav, K. V. Ramana, Y. C. Awasthi, and S. K. Srivastava, “Glutathione level regulates HNE-induced genotoxicity in human erythroleukemia cells,” Toxicology and Applied Pharmacology, vol. 227, no. 2, pp. 257–264, 2008.
- N. Zarković, K. Zarković, R. J. Schaur et al., “4-hydroxynonenal as a second messenger of free radicals and growth modifying factor,” Life Sciences, vol. 65, no. 18-19, pp. 1901–1904, 1999.
- C. A. Thompson and P. C. Burcham, “Genome-wide transcriptional responses to acrolein,” Chemical Research in Toxicology, vol. 21, no. 12, pp. 2245–2256, 2008.
- Y. S. Park and N. Taniguchi, “Acrolein induces inflammatory response underlying endothelial dysfunction: a risk factor for atherosclerosis,” Annals of the New York Academy of Sciences, vol. 1126, pp. 185–189, 2008.
- C. C. Wu, C. W. Hsieh, P. H. Lai, J. B. Lin, Y. C. Liu, and B. S. Wung, “Upregulation of endothelial heme oxygenase-1 expression through the activation of the JNK pathway by sublethal concentrations of acrolein,” Toxicology and Applied Pharmacology, vol. 214, no. 3, pp. 244–252, 2006.
- J. Roy, P. Pallepati, A. Bettaieb, A. Tanel, and D. A. Averill-Bates, “Acrolein induces a cellular stress response and triggers mitochondrial apoptosis in A549 cells,” Chemico-Biological Interactions, vol. 181, no. 2, pp. 154–167, 2009.
- J. D. Lambeth, “NOX enzymes and the biology of reactive oxygen,” Nature Reviews Immunology, vol. 4, no. 4, pp. 181–189, 2004.
- K. Bedard and K. H. Krause, “The NOX family of ROS-generating NADPH oxidases: physiology and pathophysiology,” Physiological Reviews, vol. 87, no. 1, pp. 245–313, 2007.
- K. Datta, S. Sinha, and P. Chattopadhyay, “Reactive oxygen species in health and disease,” National Medical Journal of India, vol. 13, no. 6, pp. 304–310, 2000.
- M. Valko, D. Leibfritz, J. Moncol, M. T. D. Cronin, M. Mazur, and J. Telser, “Free radicals and antioxidants in normal physiological functions and human disease,” International Journal of Biochemistry and Cell Biology, vol. 39, no. 1, pp. 44–84, 2007.
- M. Vuillaume, “Reduced oxygen species, mutation, induction and cancer initiation,” Mutation Research, vol. 186, no. 1, pp. 43–72, 1987.
- B. S. Berlett and E. R. Stadtman, “Protein oxidation in aging, disease, and oxidative stress,” Journal of Biological Chemistry, vol. 272, no. 33, pp. 20313–20316, 1997.
- M. L. Circu and T. Y. Aw, “Reactive oxygen species, cellular redox systems, and apoptosis,” Free Radical Biology and Medicine, vol. 48, no. 6, pp. 749–762, 2010.
- H. Bartsch and J. Nair, “Oxidative stress and lipid peroxidation-derived DNA-lesions in inflammation driven carcinogenesis,” Cancer Detection and Prevention, vol. 28, no. 6, pp. 385–391, 2004.
- A. Catalá, “An overview of lipid peroxidation with emphasis in outer segments of photoreceptors and the chemiluminescence assay,” International Journal of Biochemistry and Cell Biology, vol. 38, no. 9, pp. 1482–1495, 2006.
- M. Parola, G. Bellomo, G. Robino, G. Barrera, and M. U. Dianzani, “4-hydroxynonenal as a biological signal: molecular basis and pathophysiological implications,” Antioxidants and Redox Signaling, vol. 1, no. 3, pp. 255–284, 1999.
- K. Uchida, “Current status of acrolein as a lipid peroxidation product,” Trends in Cardiovascular Medicine, vol. 9, no. 5, pp. 109–113, 1999.
- G. R. Buettner, “The pecking order of free radicals and antioxidants: lipid peroxidation, α-tocopherol, and ascorbate,” Archives of Biochemistry and Biophysics, vol. 300, no. 2, pp. 535–543, 1993.
- S. Nigam and T. Schewe, “Phospholipase A2s and lipid peroxidation,” Biochimica et Biophysica Acta, vol. 1488, no. 1-2, pp. 167–181, 2000.
- H. Rubbo, S. Parthasarathy, S. Barnes, M. Kirk, B. Kalyanaraman, and B. A. Freeman, “Nitric oxide inhibition of lipoxygenase-dependent liposome and low- density lipoprotein oxidation: termination of radical chain propagation reactions and formation of nitrogen-containing oxidized lipid derivatives,” Archives of Biochemistry and Biophysics, vol. 324, no. 1, pp. 15–25, 1995.
- S. Jongberg, C. U. Carlsen, and L. H. Skibsted, “Peptides as antioxidants and carbonyl quenchers in biological model systems,” Free Radical Research, vol. 43, no. 10, pp. 932–942, 2009.
- R. Sharma, D. Brown, S. Awasthi et al., “Transfection with 4-hydroxynonenal-metabolizing glutathione S-transferase isozymes leads to phenotypic transformation and immortalization of adherent cells,” European Journal of Biochemistry, vol. 271, no. 9, pp. 1690–1701, 2004.
- J. Z. Cheng, S. S. Singhal, A. Sharma et al., “Transfection of mGSTA4 in HL-60 cells protects against 4-hydroxynonenal-induced apoptosis by inhibiting JNK-mediated signaling,” Archives of Biochemistry and Biophysics, vol. 392, no. 2, pp. 197–207, 2001.
- S. K. Srivastava, S. S. Singhal, S. Awasthi, S. Pikula, N. H. Ansari, and Y. C. Awasthi, “A glutathione S-transferases isozyme (bGST 5.8) involved in the metabolism of 4-hydroxy-2-trans-nonenal is localized in bovine lens epithelium,” Experimental Eye Research, vol. 63, no. 3, pp. 329–337, 1996.
- M. Comporti, “Lipid peroxidation and cellular damage in toxic liver injury,” Laboratory Investigation, vol. 53, no. 6, pp. 599–623, 1985.
- P. A. Baeuerle and T. Henkel, “Function and activation of NF-kappa B in the immune system,” Annual Review of Immunology, vol. 12, pp. 141–179, 1994.
- P. A. Baeuerle and D. Baltimore, “Nf-κB: ten years after,” Cell, vol. 87, no. 1, pp. 13–20, 1996.
- P. J. Barnes and M. Karin, “Nuclear factor-κB—a pivotal transcription factor in chronic inflammatory diseases,” New England Journal of Medicine, vol. 336, no. 15, pp. 1066–1071, 1997.
- S. Ghosh, M. J. May, and E. B. Kopp, “NF-κB and Rel proteins: evolutionarily conserved mediators of immune responses,” Annual Review of Immunology, vol. 16, pp. 225–260, 1998.
- W. C. Sha, “Regulation of immune responses by NF-κB/Rel transcription factors,” Journal of Experimental Medicine, vol. 187, no. 2, pp. 143–146, 1998.
- M. Grossmann, Y. Nakamura, R. Grumont, and S. Gerondakis, “New insights into the roles of ReL/NF-κB transcription factors in immune function, hemopoiesis and human disease,” International Journal of Biochemistry and Cell Biology, vol. 31, no. 10, pp. 1209–1219, 1999.
- G. Poli, F. Biasi, E. Chiaprotto, M. U. Dianzani, A. de Luca, and H. Esterbauer, “Lipid peroxidation in human diseases: evidence of red cell oxidative stress after circulatory shock,” Free Radical Biology and Medicine, vol. 6, no. 2, pp. 167–170, 1989.
- M. Polak and Z. Zagórski, “Lipid peroxidation in diabetic retinopathy,” Annales Universitatis Mariae Curie-Sklodowska. Sectio D: Medicina, vol. 59, no. 1, pp. 434–437, 2004.
- A. Higdon, A. R. Diers, J. Y. Oh, A. Landar, and V. M. Darley-Usmar, “Cell signalling by reactive lipid species: new concepts and molecular mechanisms,” Biochemical Journal, vol. 442, no. 3, pp. 453–464, 2012.
- J. Ruef, M. Moser, C. Bode, W. Kübler, and M. S. Runge, “4-hydroxynonenal induces apoptosis, NF-κB-activation and formation of 8-isoprostane in vascular smooth muscle cells,” Basic Research in Cardiology, vol. 96, no. 2, pp. 143–150, 2001.
- S. P. Faux and P. J. Howden, “Possible role of lipid peroxidation in the induction of NF-kappa B and AP-1 in RFL-6 cells by crocidolite asbestos: evidence following protection by vitamin E,” Environmental Health Perspectives, vol. 105, 5, pp. 1127–1130, 1997.
- A. L. Levonen, A. Landar, A. Ramachandran et al., “Cellular mechanisms of redox cell signalling: role of cysteine modification in controlling antioxidant defences in response to electrophilic lipid oxidation products,” Biochemical Journal, vol. 378, part 2, pp. 373–382, 2004.
- E. K. Ceaser, D. R. Moellering, S. Shiva et al., “Mechanisms of signal transduction mediated by oxidized lipids: the role of the electrophile-responsive proteome,” Biochemical Society Transactions, vol. 32, part 1, pp. 151–155, 2004.
- J. W. Zmijewski, A. Landar, N. Watanabe, D. A. Dickinson, N. Noguchi, and V. M. Darley-Usmar, “Cell signalling by oxidized lipids and the role of reactive oxygen species in the endothelium,” Biochemical Society Transactions, vol. 33, part 6, pp. 1385–1389, 2005.
- D. A. Dickinson, V. M. Darley-Usmar, and A. Landar, “The covalent advantage: a new paradigm for cell signaling by thiol reactive lipid oxidation products,” in Redox Proteomics: From Protein Modifications to Cellular Dysfunction and Diseases, I. Dalle-Donne, A. Scalone, and D. A. Butterfield, Eds., pp. 345–367, John Wiley & Sons, Indianapolis, Ind, USA, 2006.
- K. Stamatakis and D. Pérez-Sala, “Prostanoids with cyclopentenone structure as tools for the characterization of electrophilic lipid-protein interactomes,” Annals of the New York Academy of Sciences, vol. 1091, pp. 548–570, 2006.
- J. A. Doorn and D. R. Petersen, “Covalent modification of amino acid nucleophiles by the lipid peroxidation products 4-hydroxy-2-nonenal and 4-oxo-2-nonenal,” Chemical Research in Toxicology, vol. 15, no. 11, pp. 1445–1450, 2002.
- K. Uchida, “4-hydroxy-2-nonenal: a product and mediator of oxidative stress,” Progress in Lipid Research, vol. 42, no. 4, pp. 318–343, 2003.
- A. L. Isom, S. Barnes, L. Wilson, M. Kirk, L. Coward, and V. Darley-Usmar, “Modification of cytochrome c by 4-hydroxy-2-nonenal: evidence for histidine, lysine, and arginine-aldehyde adducts,” Journal of the American Society for Mass Spectrometry, vol. 15, no. 8, pp. 1136–1147, 2004.
- E. Chiarpotto, C. Domenicotti, D. Paola, et al., “Regulation of rat hepatocyte protein kinase C β isoenzymes by the lipid peroxidation product 4-hydroxy-2,3-nonenal: a signaling pathway to modulate vesicular transport of glycoproteins,” Hepatology, vol. 29, no. 5, pp. 1565–1572, 1999.
- M. Nitti, C. Domenicotti, C. D'Abramo et al., “Activation of PKC-β isoforms mediates HNE-induced MCP-1 release by macrophages,” Biochemical and Biophysical Research Communications, vol. 294, no. 3, pp. 547–552, 2002.
- M. Parola, G. Robino, F. Marra et al., “HNE interacts directly with JNK isoforms in human hepatic stellate cells,” Journal of Clinical Investigation, vol. 102, no. 11, pp. 1942–1950, 1998.
- B. J. Song, Y. Soh, M. A. Bae, J. E. Pie, J. Wan, and K. S. Jeong, “Apoptosis of PC12 cells by 4-hydroxy-2-nonenal is mediated through selective activation of the c-Jun N-Terminal protein kinase pathway,” Chemico-Biological Interactions, vol. 130–132, pp. 943–954, 2001.
- N. Shibata, Y. Kato, Y. Inose et al., “4-hydroxy-2-nonenal upregulates and phosphorylates cytosolic phospholipase A2 in cultured Ra2 microglial cells via MAPK pathways,” Neuropathology, vol. 31, no. 2, pp. 122–128, 2011.
- S. J. Lee, C. E. Kim, M. R. Yun et al., “4-hydroxynonenal enhances MMP-9 production in murine macrophages via 5-lipoxygenase-mediated activation of ERK and p38 MAPK,” Toxicology and Applied Pharmacology, vol. 242, no. 2, pp. 191–198, 2010.
- S. Saito, G. D. Frank, M. Mifune et al., “Ligand-independent trans-activation of the platelet-derived growth factor receptor by reactive oxygen species requires protein kinase C-δ and c-Src,” Journal of Biological Chemistry, vol. 277, no. 47, pp. 44695–44700, 2002.
- P. Chaudhary, R. Sharma, A. Sharma et al., “Mechanisms of 4-hydroxy-2-nonenal induced pro- and anti-apoptotic signaling,” Biochemistry, vol. 49, no. 29, pp. 6263–6275, 2010.
- S. Dwivedi, A. Sharma, B. Patrick, R. Sharma, and Y. C. Awasthi, “Role of 4-hydroxynonenal and its metabolites in signaling,” Redox Report, vol. 12, no. 1-2, pp. 4–10, 2007.
- K. V. Ramana, A. Bhatnagar, S. Srivastava et al., “Mitogenic responses of vascular smooth muscle cells to lipid peroxidation-derived aldehyde 4-hydroxy-trans-2-nonenal (HNE): role of aldose reductase-catalyzed reduction of the HNE-glutathione conjugates in regulating cell growth,” Journal of Biological Chemistry, vol. 281, no. 26, pp. 17652–17660, 2006.
- K. V. Ramana, M. S. Willis, M. D. White et al., “Endotoxin-induced cardiomyopathy and systemic inflammation in mice is prevented by aldose reductase inhibition,” Circulation, vol. 114, no. 17, pp. 1838–1846, 2006.
- K. V. Ramana, “Aldose reductase: new insights for an old enzyme,” BioMolecular Concepts, vol. 2, no. 1-2, pp. 103–114, 2011.
- H. J. Forman, M. Maiorino, and F. Ursini, “Signaling functions of reactive oxygen species,” Biochemistry, vol. 49, no. 5, pp. 835–842, 2010.
- J. Segovia, A. Sabbah, V. Mgbemena et al., “TLR2/MyD88/NF-B pathway, reactive oxygen species, potassium efflux activates NLRP3/ASC inflammasome during respiratory syncytial virus infection,” PLoS One, vol. 7, no. 1, Article ID e29695, 2012.
- S. Mena, A. Ortega, and J. M. Estrela, “Oxidative stress in environmental-induced carcinogenesis,” Mutation Research, vol. 674, no. 1-2, pp. 36–44, 2009.
- A. Auerbach and M. L. Hernandez, “The effect of environmental oxidative stress on airway inflammation,” Current Opinion in Allergy and Clinical Immunology, vol. 12, no. 2, pp. 133–139, 2012.
- K. J. Chuang, C. C. Chan, T. C. Su, C. T. Lee, and C. S. Tang, “The effect of urban air pollution on inflammation, oxidative stress, coagulation, and autonomic dysfunction in young adults,” American Journal of Respiratory and Critical Care Medicine, vol. 176, no. 4, pp. 370–376, 2007.
- E. Profumo, B. Buttari, and R. Riganò, “Oxidative stress in cardiovascular inflammation: its involvement in autoimmune responses,” International Journal of Inflammation, vol. 2011, Article ID 295705, 6 pages, 2011.
- V. J. Thannickal and B. L. Fanburg, “Reactive oxygen species in cell signaling,” American Journal of Physiology—Lung Cellular and Molecular Physiology, vol. 279, no. 6, pp. L1005–L1028, 2000.
- P. D. Ray, B. W. Huang, and Y. Tsuji, “Reactive oxygen species (ROS) homeostasis and redox regulation in cellular signaling,” Cellular Signalling, vol. 24, no. 5, pp. 981–990, 2012.
- K. V. Ramana, A. A. Fadl, R. Tammali, A. B. M. Reddy, A. K. Chopra, and S. K. Srivastava, “Aldose reductase mediates the lipopolysaccharide-induced release of inflammatory mediators in RAW264.7 murine macrophages,” Journal of Biological Chemistry, vol. 281, no. 44, pp. 33019–33029, 2006.
- R. Tammali, K. V. Ramana, S. S. Singhal, S. Awasthi, and S. K. Srivastava, “Aldose reductase regulates growth factor-induced cyclooxygenase-2 expression and prostaglandin E2 production in human colon cancer cells,” Cancer Research, vol. 66, no. 19, pp. 9705–9713, 2006.
- S. K. Srivastava, U. C. Yadav, A. B. Reddy et al., “Aldose reductase inhibition suppresses oxidative stress-induced inflammatory disorders,” Chemico-Biological Interactions, vol. 191, no. 1–3, pp. 330–338, 2011.
- S. J. Lee, C. E. Kim, K. W. Seo, and C. D. Kim, “HNE-induced 5-LO expression is regulated by NF-κB/ERK and Sp1/p38 MAPK pathways via EGF receptor in murine macrophages,” Cardiovascular Research, vol. 88, no. 2, pp. 352–359, 2010.
- S. J. Lee, K. W. Seo, M. R. Yun et al., “4-hydroxynonenal enhances MMP-2 production in vascular smooth muscle cells via mitochondrial ROS-mediated activation of the Akt/NF-κB signaling pathways,” Free Radical Biology and Medicine, vol. 45, no. 10, pp. 1487–1492, 2008.
- H. Zhang and H. J. Forman, “Acrolein induces heme oxygenase-1 through PKC-δ and PI3K in human bronchial epithelial cells,” American Journal of Respiratory Cell and Molecular Biology, vol. 38, no. 4, pp. 483–490, 2008.
- A. Tanel and D. A. Averill-Bates, “P38 and ERK mitogen-activated protein kinases mediate acrolein-induced apoptosis in Chinese hamster ovary cells,” Cellular Signalling, vol. 19, no. 5, pp. 968–977, 2007.
- H. Zhang and H. J. Forman, “Signaling pathways involved in phase II gene induction by α, Β-unsaturated aldehydes,” Toxicology and Industrial Health, vol. 25, no. 4-5, pp. 269–278, 2009.
- Y. Q. Fu, F. Fang, Z. Y. Lu, F. W. Kuang, and F. Xu, “N-acetylcysteine protects alveolar epithelial cells from hydrogen peroxideinduced apoptosis through scavenging reactive oxygen species and suppressing c-Jun N-terminal kinase,” Experimental Lung Research, vol. 36, no. 6, pp. 352–361, 2010.
- S. Umar, J. Zargan, K. Umar, S. Ahmad, C. K. Katiyar, and H. A. Khan, “Modulation of the oxidative stress and inflammatory cytokine response by thymoquinone in the collagen induced arthritis in Wistar rats,” Chemico-Biological Interactions, vol. 197, no. 1, pp. 40–46, 2012.
- J. M. Müller, R. A. Rupec, and P. A. Baeuerle, “Study of gene regulation by NF-κB and AP-1 in response to reactive oxygen intermediates,” Methods, vol. 11, no. 3, pp. 301–312, 1997.
- M. Meyer, H. L. Pahl, and P. A. Baeuerle, “Regulation of the transcription factors NF-κB and AP-1 by redox changes,” Chemico-Biological Interactions, vol. 91, no. 2-3, pp. 91–100, 1994.
- H. Bartsch and J. Nair, “Chronic inflammation and oxidative stress in the genesis and perpetuation of cancer: role of lipid peroxidation, DNA damage, and repair,” Langenbeck's Archives of Surgery, vol. 391, no. 5, pp. 499–510, 2006.
- P. Amstad and P. Cerutti, “Genetic modulation of the cellular antioxidant defense capacity,” Environmental Health Perspectives, vol. 88, pp. 77–82, 1990.
- P. Cerutti, R. Ghosh, Y. Oya, and P. Amstad, “The role of the cellular antioxidant defense in oxidant carcinogenesis,” Environmental Health Perspectives, vol. 102, no. 10, pp. 123–129, 1994.
- J. H. Limón-Pacheco and M. E. Gonsebatt, “The glutathione system and its regulation by neurohormone melatonin in the central nervous system,” Central Nervous System Agents in Medicinal Chemistry, vol. 10, no. 4, pp. 287–297, 2010.
- N. Ballatori, S. M. Krance, S. Notenboom, S. Shi, K. Tieu, and C. L. Hammond, “Glutathione dysregulation and the etiology and progression of human diseases,” Biological Chemistry, vol. 390, no. 3, pp. 191–214, 2009.
- M. Valko, D. Leibfritz, J. Moncol, M. T. D. Cronin, M. Mazur, and J. Telser, “Free radicals and antioxidants in normal physiological functions and human disease,” International Journal of Biochemistry and Cell Biology, vol. 39, no. 1, pp. 44–84, 2007.
- N. Tailor and M. Sharma, “Antioxidant hybrid compounds: a promising therapeutic intervention in oxidative stress induced diseases,” Mini-Reviews in Medicinal Chemistry, vol. 13, no. 2, pp. 280–297, 2013.
- M. H. Hopkins, V. Fedirko, D. P. Jones, P. D. Terry, and R. M. Bostick, “Antioxidant micronutrients and biomarkers of oxidative stress and inflammation in colorectal adenoma patients: results from a randomized, controlled clinical trial,” Cancer Epidemiology Biomarkers and Prevention, vol. 19, no. 3, pp. 850–858, 2010.
- Z. Mazloom, N. Hejazi, M. H. Dabbaghmanesh, H. R. Tabatabaei, A. Ahmadi, and H. Ansar, “Effect of vitamin C supplementation on postprandial oxidative stress and lipid profile in type 2 diabetic patients,” Pakistan Journal of Biological Sciences, vol. 14, no. 19, pp. 900–904, 2011.
- M. Goodman, R. M. Bostick, O. Kucuk, and D. P. Jones, “Clinical trials of antioxidants as cancer prevention agents: past, present, and future,” Free Radical Biology and Medicine, vol. 51, no. 5, pp. 1068–1084, 2011.
- E. C. Ienco, A. LoGerfo, C. Carlesi et al., “Oxidative stress treatment for clinical trials in neurodegenerative diseases,” Journal of Alzheimer's Disease, vol. 24, no. 2, pp. 111–126, 2011.
- E. R. Greenberg, J. A. Baron, T. D. Tosteson et al., “A clinical trial of antioxidant vitamins to prevent colorectal adenoma,” New England Journal of Medicine, vol. 331, no. 3, pp. 141–147, 1994.
- M. C. Mathew, A. M. Ervin, J. Tao, and R. M. Davis, “Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract,” Cochrane Database of Systematic Reviews, vol. 6, Article ID CD004567, 2012.
- U. C. S. Yadav, N. M. Kalariya, and K. V. Ramana, “Emerging role of antioxidants in the protection of uveitis complications,” Current Medicinal Chemistry, vol. 18, no. 6, pp. 931–942, 2011.
- S. K. Srivastava, K. V. Ramana, and A. Bhatnagar, “Role of aldose reductase and oxidative damage in diabetes and the consequent potential for therapeutic options,” Endocrine Reviews, vol. 26, no. 3, pp. 380–392, 2005.
- K. V. Ramana, B. L. Dixit, S. Srivastava, G. K. Balendiran, S. K. Srivastava, and A. Bhatnagar, “Selective recognition of glutathiolated aldehydes by aldose reductase,” Biochemistry, vol. 39, no. 40, pp. 12172–12180, 2000.
- B. L. Dixit, G. K. Balendiran, S. J. Watowich et al., “Kinetic and structural characterization of the glutathione-binding site of aldose reductase,” Journal of Biological Chemistry, vol. 275, no. 28, pp. 21587–21595, 2000.
- A. D. Morrison, R. S. Clements Jr., S. B. Travis, F. Oski, and A. I. Winegrad, “Glucose utilization by the polyol pathway in human erythrocytes,” Biochemical and Biophysical Research Communications, vol. 40, no. 1, pp. 199–205, 1970.
- R. Singh, M. A. White, K. V. Ramana et al., “Structure of a glutathione conjugate bound to the active site of aldose reductase,” Proteins, vol. 64, no. 1, pp. 101–110, 2006.
- K. V. Ramana, B. L. Dixit, S. Srivastava et al., “Characterization of the glutathione binding site of aldose reductase,” Chemico-Biological Interactions, vol. 130–132, pp. 537–548, 2001.
- H. J. Forman, “Reactive oxygen species and α,β-unsaturated aldehydes as second messengers in signal transduction,” Annals of the New York Academy of Sciences, vol. 1203, pp. 35–44, 2010.
- H. J. Forman, J. M. Fukuto, T. Miller, H. Zhang, A. Rinna, and S. Levy, “The chemistry of cell signaling by reactive oxygen and nitrogen species and 4-hydroxynonenal,” Archives of Biochemistry and Biophysics, vol. 477, no. 2, pp. 183–195, 2008.
- K. Uchida, “Lipid peroxidation and redox-sensitive signaling pathways,” Current Atherosclerosis Reports, vol. 9, no. 3, pp. 216–221, 2007.
- K. Uchida, “Role of reactive aldehyde in cardiovascular diseases,” Free Radical Biology and Medicine, vol. 28, no. 12, pp. 1685–1696, 2000.
- O. Kutuk and H. Basaga, “Apoptosis signalling by 4-hydroxynonenal: a role for JNK-c-Jun/AP-1 pathway,” Redox Report, vol. 12, no. 1-2, pp. 30–34, 2007.