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Mahgoup EM, Khaleel SA, El-Mahdy MA, Zweier JL. Electronic Cigarette Vape Decreases Nitric Oxide Bioavailability in Vascular Smooth Muscle Cells via Increased Cytoglobin-Mediated Metabolism. Free Radic Biol Med 2024:S0891-5849(24)01166-3. [PMID: 39743029 DOI: 10.1016/j.freeradbiomed.2024.12.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2024] [Revised: 12/16/2024] [Accepted: 12/29/2024] [Indexed: 01/04/2025]
Abstract
Cytoglobin (Cygb) regulates vascular tone by modulating nitric oxide (NO) metabolism in vascular smooth muscle cells (VSMCs). In the presence of its cytochrome B5a (B5)/B5 reductase-isoform-3 (B5R) reducing system, Cygb controls NO metabolism via oxygen-dependent NO dioxygenation. Electronic cigarette (EC) use has been shown to induce vascular dysfunction and decrease NO bioavailability; however, the role of Cygb-mediated NO metabolism in the pathophysiology of this process has not been previously investigated. Therefore, we utilized aortic VSMCs with EC vape extract (ECE) exposure to elucidate the effects of EC vape constituents on NO degradation and alterations in the process of Cygb-mediated NO metabolism. VSMCs were exposed to ECE, either nicotine-free (ECEV) or nicotine-containing (ECEN), for various durations. NO decay rates were measured along with cellular expression of Cygb and its B5/B5R reducing system. Exposure to ECEV led to a much higher rate of NO consumption by VSMCs, with an even larger effect following ECEN exposure. With four hours of exposure, a modest increase in NO decay rate occurred that was followed by much higher increases with exposure times of 24 to 48 hours. This effect was paralleled by upregulation of Cygb and B5/B5R expression. siRNA-mediated knock-down of Cygb expression largely reversed this ECE-induced increase in NO metabolism rate. Thus, ECE exposure led to increased Cygb-mediated NO metabolism in VSMCs with diminished NO bioavailability, which in turn can play a key role in EC-induced vascular dysfunction.
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Zweier JL, Kundu T, Eid MS, Hemann C, Leimkühler S, El-Mahdy MA. Nicotine inhalation and metabolism triggers AOX-mediated superoxide generation with oxidative lung injury. J Biol Chem 2024; 300:107626. [PMID: 39098528 PMCID: PMC11403528 DOI: 10.1016/j.jbc.2024.107626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 07/22/2024] [Accepted: 07/24/2024] [Indexed: 08/06/2024] Open
Abstract
With the increasing use of vaping devices that deliver high levels of nicotine (NIC) to the lungs, sporadic lung injury has been observed. Commercial vaping solutions can contain high NIC concentrations of 150 mM or more. With high NIC levels, its metabolic products may induce toxicity. NIC is primarily metabolized to form NIC iminium (NICI) which is further metabolized by aldehyde oxidase (AOX) to cotinine. We determine that NICI in the presence of AOX is a potent trigger of superoxide generation. NICI stimulated superoxide generation from AOX with Km = 2.7 μM and Vmax = 794 nmol/min/mg measured by cytochrome-c reduction. EPR spin-trapping confirmed that NICI in the presence of AOX is a potent source of superoxide. AOX is expressed in the lungs and chronic e-cigarette exposure in mice greatly increased AOX expression. NICI or NIC stimulated superoxide production in the lungs of control mice with an even greater increase after chronic e-cigarette exposure. This superoxide production was quenched by AOX inhibition. Furthermore, e-cigarette-mediated NIC delivery triggered oxidative lung damage that was blocked by AOX inhibition. Thus, NIC metabolism triggers AOX-mediated superoxide generation that can cause lung injury. Therefore, high uncontrolled levels of NIC inhalation, as occur with e-cigarette use, can induce oxidative lung damage.
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Ewees MG, El-Mahdy MA, Hannawi Y, Zweier JL. Tobacco cigarette smoking induces cerebrovascular dysfunction followed by oxidative neuronal injury with the onset of cognitive impairment. J Cereb Blood Flow Metab 2024:271678X241270415. [PMID: 39136181 PMCID: PMC11572251 DOI: 10.1177/0271678x241270415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/21/2024] [Accepted: 06/25/2024] [Indexed: 09/26/2024]
Abstract
While chronic smoking triggers cardiovascular disease, controversy remains regarding its effects on the brain and cognition. We investigated the effects of long-term cigarette smoke (CS) exposure (CSE) on cerebrovascular function, neuronal injury, and cognition in a novel mouse exposure model. Longitudinal studies were performed in CS or air-exposed mice, 2 hours/day, for up to 60 weeks. Hypertension and carotid vascular endothelial dysfunction (VED) occurred by 16 weeks of CSE, followed by reduced carotid artery blood flow, with oxidative stress detected in the carotid artery, and subsequently in the brain of CS-exposed mice with generation of reactive oxygen species (ROS) and secondary protein and DNA oxidation, microglial activation and astrocytosis. Brain small vessels exhibited decreased levels of endothelial NO synthase (eNOS), enlarged perivascular spaces with blood brain barrier (BBB) leak and decreased levels of tight-junction proteins. In the brain, amyloid-β deposition and phosphorylated-tau were detected with increases out to 60 weeks, at which time mice exhibited impaired spatial learning and memory. Thus, long-term CSE initiates a cascade of ROS generation and oxidative damage, eNOS dysfunction with cerebral hypoperfusion, as well as cerebrovascular and BBB damage with intracerebral inflammation, and neuronal degeneration, followed by the onset of impaired cognition and memory.
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Hazzaa HH, Attia MS, Shiekh MAE, Grawish ME, Ghoneim MMI, Adly NM, Shams NS, El-Mahdy MA, Elewa GM. Use of Melatonin/Decorticotomy and Autogenous Bone Graft in Induced 1-Wall Defect. Int Dent J 2022:S0020-6539(22)00258-1. [PMID: 36543730 DOI: 10.1016/j.identj.2022.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/03/2022] [Accepted: 11/05/2022] [Indexed: 12/24/2022] Open
Abstract
PURPOSE This study was designed to investigate the effect of intramarrow penetration (IMP) and 1% melatonin (MLN) gel on the remodelling process of autogenous bone graft (ABG) in an induced 1-osseous wall defect model. METHODS Sixty-four intrabony induced mandibular defects were created on the distal side of premolars-P1, P2, P3, and P4 (on each side)-in 8 beagle dogs. A ligature-induced periodontitis was initiated in each defect. Defects were then divided into 4 equal groups. Group I was treated with open-flap debridement (OFD) alone, group II was treated with OFD/ABG, group III was treated with OFD/IMP/ABG, and group IV was treated with OFD/ABG/IMP/1% MLN gel. The study parameters were bone fill, histologic analysis, and immunohistochemical evaluation of endothelial nitric oxide synthase (eNOS) expression at 2-week (2W) and 8-week (8W) time intervals. RESULTS At 8W, significant differences were revealed amongst all groups regarding the amount of bone fill and eNOS expressions (P < .001). Bone fill percentages were 55.5%, 22.3%, 16.8%, and 0% in groups IV, III, II, and I, respectively. eNOS expressions were 1.68 ± 0.06, 8.43 ± 0.04, 16.80 ± 0.17, and 1.97 ± 0.07 in groups IV, III, II, and I, respectively. The favourable results were in line with group IV. CONCLUSIONS According to these preliminary results, defects treated by ABG augmented with IMP and 1% MLN gel revealed a greater amount of bone fill and reduced eNOS expression. This combination is therefore highly suggested as an adjunct to ABG.
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Mahgoup EM, Khaleel SA, El-Mahdy MA, Abd-Allah AR, Zweier JL. Role of cytoglobin in cigarette smoke constituent-induced loss of nitric oxide bioavailability in vascular smooth muscle cells. Nitric Oxide 2022; 119:9-18. [PMID: 34875385 PMCID: PMC8752519 DOI: 10.1016/j.niox.2021.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/22/2021] [Accepted: 12/03/2021] [Indexed: 02/03/2023]
Abstract
Cytoglobin (Cygb) has been identified as the major nitric oxide (NO) metabolizing protein in vascular smooth muscle cells (VSMCs) and is crucial for the regulation of vascular tone. In the presence of its requisite cytochrome B5a (B5)/B5 reductase-isoform-3 (B5R) reducing system, Cygb controls NO metabolism through the oxygen-dependent process of NO dioxygenation. Tobacco cigarette smoking (TCS) induces vascular dysfunction; however, the role of Cygb in the pathophysiology of TCS-induced cardiovascular disease has not been previously investigated. While TCS impairs NO biosynthesis, its effect on NO metabolism remains unclear. Therefore, we performed studies in aortic VSMCs with tobacco smoke extract (TSE) exposure to investigate the effects of cigarette smoke constituents on the rates of NO decay, with focus on the alterations that occur in the process of Cygb-mediated NO metabolism. TSE greatly enhanced the rates of NO metabolism by VSMCs. An initial increase in superoxide-mediated NO degradation was seen at 4 h of exposure. This was followed by much larger progressive increases at 24 and 48 h, accompanied by parallel increases in the expression of Cygb and B5/B5R. siRNA-mediated Cygb knockdown greatly decreased these TSE-induced elevations in NO decay rates. Therefore, upregulation of the levels of Cygb and its reducing system accounted for the large increase in NO metabolism rate seen after 24 h of TSE exposure. Thus, increased Cygb-mediated NO degradation would contribute to TCS-induced vascular dysfunction and partial inhibition of Cygb expression or its NO dioxygenase function could be a promising therapeutic target to prevent secondary cardiovascular disease.
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El-Mahdy MA, Ewees MG, Eid MS, Mahgoup EM, Khaleel SA, Zweier JL. Electronic Cigarette Exposure Causes Vascular Endothelial Dysfunction Due to NADPH Oxidase Activation and eNOS Uncoupling. Am J Physiol Heart Circ Physiol 2022; 322:H549-H567. [PMID: 35089811 PMCID: PMC8917923 DOI: 10.1152/ajpheart.00460.2021] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We recently reported a mouse model of chronic electronic cigarette (e-cig) exposure-induced cardiovascular pathology, where long-term exposure to e-cig vape (ECV) induces cardiac abnormalities, impairment of endothelial function, and systemic hypertension. Here, we delineate the underlying mechanisms of ECV-induced vascular endothelial dysfunction (VED), a central trigger of cardiovascular disease. C57/BL6 male mice were exposed to ECV generated from e-cig liquid containing 0, 6, or 24 mg/ml nicotine for 16 and 60 weeks. Time-dependent elevation in blood pressure and systemic vascular resistance were observed, along with an impairment of acetylcholine-induced aortic relaxation in ECV-exposed mice, compared to air-exposed control. Decreased intravascular nitric oxide (NO) levels and increased superoxide generation with elevated 3-nitrotyrosine levels in the aorta of ECV-exposed mice were observed, indicating that ECV-induced superoxide reacts with NO to generate cytotoxic peroxynitrite. Exposure increased NADPH oxidase expression, supporting its role in ECV-induced superoxide generation. Downregulation of endothelial nitric oxide synthase (eNOS) expression and Akt-dependent eNOS phosphorylation occurred in the aorta of ECV-exposed mice, indicating that exposure inhibited de novo NO synthesis. Following ECV exposure, the critical NOS cofactor tetrahydrobiopterin was decreased, with a concomitant loss of its salvage enzyme, dihydrofolate reductase. NADPH oxidase and NOS inhibitors abrogated ECV-induced superoxide generation in the aorta of ECV exposed mice. Together, our data demonstrate that ECV exposure activates NADPH oxidase and uncouples eNOS, causing a vicious cycle of superoxide generation and vascular oxidant stress that triggers VED and hypertension with predisposition to other cardiovascular disease.
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Zweier JL, Hemann C, Kundu T, Ewees MG, Khaleel SA, Samouilov A, Ilangovan G, El-Mahdy MA. Cytoglobin has potent superoxide dismutase function. Proc Natl Acad Sci U S A 2021; 118:e2105053118. [PMID: 34930834 PMCID: PMC8719900 DOI: 10.1073/pnas.2105053118] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 12/13/2022] Open
Abstract
Cytoglobin (Cygb) was discovered as a novel type of globin that is expressed in mammals; however, its functions remain uncertain. While Cygb protects against oxidant stress, the basis for this is unclear, and the effect of Cygb on superoxide metabolism is unknown. From dose-dependent studies of the effect of Cygb on superoxide catabolism, we identify that Cygb has potent superoxide dismutase (SOD) function. Initial assays using cytochrome c showed that Cygb exhibits a high rate of superoxide dismutation on the order of 108 M-1 ⋅ s-1 Spin-trapping studies also demonstrated that the rate of Cygb-mediated superoxide dismutation (1.6 × 108 M-1 ⋅ s-1) was only ∼10-fold less than Cu,Zn-SOD. Stopped-flow experiments confirmed that Cygb rapidly dismutates superoxide with rates within an order of magnitude of Cu,Zn-SOD or Mn-SOD. The SOD function of Cygb was inhibited by cyanide and CO that coordinate to Fe3+-Cygb and Fe2+-Cygb, respectively, suggesting that dismutation involves iron redox cycling, and this was confirmed by spectrophotometric titrations. In control smooth-muscle cells and cells with siRNA-mediated Cygb knockdown subjected to extracellular superoxide stress from xanthine/xanthine oxidase or intracellular superoxide stress triggered by the uncoupler, menadione, Cygb had a prominent role in superoxide metabolism and protected against superoxide-mediated death. Similar experiments in vessels showed higher levels of superoxide in Cygb-/- mice than wild type. Thus, Cygb has potent SOD function and can rapidly dismutate superoxide in cells, conferring protection against oxidant injury. In view of its ubiquitous cellular expression at micromolar concentrations in smooth-muscle and other cells, Cygb can play an important role in cellular superoxide metabolism.
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Wang QE, Zhu Q, Wani G, El-Mahdy MA, Li J, Wani AA. Correction to 'DNA repair factor XPC is modified by SUMO-1 and ubiquitin following UV irradiation'. Nucleic Acids Res 2021; 49:12603-12604. [PMID: 34850104 PMCID: PMC8643675 DOI: 10.1093/nar/gkab1165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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El-Mahdy MA, Mahgoup EM, Ewees MG, Eid MS, Abdelghany TM, Zweier JL. Long-term electronic cigarette exposure induces cardiovascular dysfunction similar to tobacco cigarettes: role of nicotine and exposure duration. Am J Physiol Heart Circ Physiol 2021; 320:H2112-H2129. [PMID: 33606584 DOI: 10.1152/ajpheart.00997.2020] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Electronic cigarette (e-cig) vaping (ECV) has been proposed as a safer alternative to tobacco cigarette smoking (TCS); however, this remains controversial due to a lack of long-term comparative studies. Therefore, we developed a chronic mouse exposure model that mimics human vaping and allows comparison with TCS. Longitudinal studies were performed to evaluate alterations in cardiovascular function with TCS and ECV exposure durations of up to 60 wk. For ECV, e-cig liquid with box-mod were used and for TCS, 3R4F-cigarettes. C57/BL6 male mice were exposed 2 h/day, 5 days/wk to TCS, ECV, or air control. The role of vape nicotine levels was evaluated using e-cig-liquids with 0, 6, or 24 mg/mL nicotine. Following 16-wk exposure, increased constriction to phenylephrine and impaired endothelium-dependent and endothelium-independent vasodilation were observed in aortic segents, paralleling the onset of systemic hypertension, with elevations in systemic vascular resistance. Following 32 wk, TCS and ECV induced cardiac hypertrophy. All of these abnormalities further increased out to 60 wk of exposure, with elevated heart weight and aortic thickness along with increased superoxide production in vessels and cardiac tissues of both ECV and TCS mice. While ECV-induced abnormalities were seen in the absence of nicotine, these occurred earlier and were more severe with higher nicotine exposure. Thus, long-term vaping of e-cig can induce cardiovascular disease similar to TCS, and the severity of this toxicity increases with exposure duration and vape nicotine content.NEW & NOTEWORTHY A chronic mouse exposure model that mimics human e-cigarette vaping and allows comparison with tobacco cigarette smoking was developed and utilized to perform longitudinal studies of alterations in cardiovascular function. E-cigarette exposure led to the onset of cardiovascular disease similar to that with tobacco cigarette smoking. Impaired endothelium-dependent and endothelium-independent vasodilation with increased adrenergic vasoconstriction were observed, paralleling the onset of systemic hypertension and subsequent cardiac hypertrophy. This cardiovascular toxicity was dependent on exposure duration and nicotine dose.
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Ilangovan G, Khaleel SA, Kundu T, Hemann C, El-Mahdy MA, Zweier JL. Defining the reducing system of the NO dioxygenase cytoglobin in vascular smooth muscle cells and its critical role in regulating cellular NO decay. J Biol Chem 2021; 296:100196. [PMID: 33334890 PMCID: PMC7948950 DOI: 10.1074/jbc.ra120.016394] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/07/2020] [Accepted: 12/15/2020] [Indexed: 12/27/2022] Open
Abstract
In smooth muscle, cytoglobin (Cygb) functions as a potent nitric oxide (NO) dioxygenase and regulates NO metabolism and vascular tone. Major questions remain regarding which cellular reducing systems regulate Cygb-mediated NO metabolism. To better define the Cygb-mediated NO dioxygenation process in vascular smooth muscle cells (SMCs), and the requisite reducing systems that regulate cellular NO decay, we assessed the intracellular concentrations of Cygb and its putative reducing systems and examined their roles in the process of NO decay. Cygb and the reducing systems, cytochrome b5 (B5)/cytochrome b5 reductase (B5R) and cytochrome P450 reductase (CPR) were measured in aortic SMCs. Intracellular Cygb concentration was estimated as 3.5 μM, while B5R, B5, and CPR were 0.88, 0.38, and 0.15 μM, respectively. NO decay in SMCs was measured following bolus addition of NO to air-equilibrated cells. siRNA-mediated knockdown experiments indicated that ∼78% of NO metabolism in SMCs is Cygb-dependent. Of this, ∼87% was B5R- and B5-dependent. CPR knockdown resulted in a small decrease in the NO dioxygenation rate (VNO), while depletion of ascorbate had no effect. Kinetic analysis of VNO for the B5/B5R/Cygb system with variation of B5 or B5R concentrations from their SMC levels showed that VNO exhibits apparent Michaelis-Menten behavior for B5 and B5R. In contrast, linear variation was seen with change in Cygb concentration. Overall, B5/B5R was demonstrated to be the major reducing system supporting Cygb-mediated NO metabolism in SMCs with changes in cellular B5/B5R levels modulating the process of NO decay.
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Zweier JL, Shalaan MT, Samouilov A, Saleh IG, El-Mahdy MA. Whole body electronic cigarette exposure system for efficient evaluation of diverse inhalation conditions and products. Inhal Toxicol 2020; 32:477-486. [PMID: 33256483 DOI: 10.1080/08958378.2020.1850935] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Objectives: To develop and test a new system for whole body exposure of small animals to support investigation of the biological effects of aerosol generated by electronic cigarette (e-cig) products under diverse inhalation conditions with improved control and monitoring of the e-cig vape exposure and nicotine delivered to the animal's systemic circulation. Methods: A computer-controlled design, with built-in sensors for real time monitoring of O2, CO2, relative humidity, and temperature within the exposure chambers and port for measuring total particulate matter (TPM) was developed, constructed and tested. This design accommodates a variety of commercial vaping devices, offers software flexibility to adjust exposure protocols to mimic different users' puffing patterns, enables variable nicotine delivery to the animal's systemic circulation; minimizes travel time and alterations of aerosol quality or quantity by delivering aerosol directly to the exposure chamber, offers local or remote operation of up to six distinct exposure chambers from a single control unit, and can simultaneously test different exposure conditions or products in diverse animal groups, which reduces inter-run variability, saves time, and increases productivity. Results: The time course pattern of TPM concentration during different phases of the exposure cycle was measured. With increased puffing duration or number of exposure cycles, higher TPM exposure and plasma cotinine levels were observed with plasma cotinine levels in the range reported in light or heavy smokers. Conclusion: Overall, this novel, versatile, and durable exposure system facilitates high-throughput evaluation of the relative safety and potential toxicity of a variety of e-cig devices and liquids.
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El-Mahdy MA, Alzarie YA, Hemann C, Badary OA, Nofal S, Zweier JL. The novel SOD mimetic GC4419 increases cancer cell killing with sensitization to ionizing radiation while protecting normal cells. Free Radic Biol Med 2020; 160:630-642. [PMID: 32739595 PMCID: PMC7704930 DOI: 10.1016/j.freeradbiomed.2020.07.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 07/23/2020] [Accepted: 07/25/2020] [Indexed: 02/08/2023]
Abstract
While radiotherapy is a widely used treatment for many types of human cancer, problems of radio-resistance and side effects remain. Side effects induced by ionizing radiation (IR) arise primarily from its propensity to trigger inflammation and oxidative stress with damage of normal cells and tissues near the treatment area. The highly potent superoxide dismutase mimetic, GC4419 (Galera Therapeutics), rapidly enters cells and is highly effective in dismutating superoxide (O2•-). We performed studies to assess the potency of GC4419 in cancer killing and radio-sensitization in human lung cancer cells and normal immortalized lung cells. Treatment with GC4419 did not alter the radical generation during IR, primarily hydroxyl radical (.OH); however, it quenched the increased levels of O2•- detected in the cancer cells before and following IR. GC4419 triggered cancer cell death and inhibited cancer cell proliferation with no adverse effect on normal cells. Combination of GC4419 with IR augmented the cytotoxic effects of IR on cancer cells compared to monotherapy, while protecting normal cells from IR-induced cell death. DNA fragmentation and caspase-3 activity assays showed that combination of GC4419 with IR enhances cancer cell apoptosis. Moreover, GC4419 increased IR-induced Bax levels with decreased Bcl-2 and elevated Bax/Bcl-2 ratio following treatment. GC4419 increased TrxR activity in the normal cells but decreased activity in cancer cells, conferring increased cancer cell sensitivity to oxidative stress. In conclusion, GC4419 increases the cytotoxic and pro-apoptotic activity of IR in lung cancer cells while decreasing injury in normal cells.
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El-Mahdy MA, Abdelghany TM, Hemann C, Ewees MG, Mahgoup EM, Eid MS, Shalaan MT, Alzarie YA, Zweier JL. Chronic cigarette smoke exposure triggers a vicious cycle of leukocyte and endothelial-mediated oxidant stress that results in vascular dysfunction. Am J Physiol Heart Circ Physiol 2020; 319:H51-H65. [PMID: 32412791 DOI: 10.1152/ajpheart.00657.2019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although there is a strong association between cigarette smoking exposure (CSE) and vascular endothelial dysfunction (VED), the underlying mechanisms by which CSE triggers VED remain unclear. Therefore, studies were performed to define these mechanisms using a chronic mouse model of cigarette smoking (CS)-induced cardiovascular disease mirroring that in humans. C57BL/6 male mice were subjected to CSE for up to 48 wk. CSE impaired acetylcholine (ACh)-induced relaxation of aortic and mesenteric segments and triggered hypertension, with mean arterial blood pressure at 32 and 48 wk of exposure of 122 ± 6 and 135 ± 5 mmHg compared with 99 ± 4 and 102 ± 6 mmHg, respectively, in air-exposed mice. CSE led to monocyte activation with superoxide generation in blood exiting the pulmonary circulation. Macrophage infiltration with concomitant increase in NADPH oxidase subunits p22phox and gp91phox was seen in aortas of CS-exposed mice at 16 wk, with further increase out to 48 wk. Associated with this, increased superoxide production was detected that decreased with Nox inhibition. Tetrahydrobiopterin was progressively depleted in CS-exposed mice but not in air-exposed controls, resulting in endothelial nitric oxide synthase (eNOS) uncoupling and secondary superoxide generation. CSE led to a time-dependent decrease in eNOS and Akt expression and phosphorylation. Overall, CSE induces vascular monocyte infiltration with increased NADPH oxidase-mediated reactive oxygen species generation and depletes the eNOS cofactor tetrahydrobiopterin, uncoupling eNOS and triggering a vicious cycle of oxidative stress with VED and hypertension. Our study provides important insights toward understanding the process by which smoking contributes to the genesis of cardiovascular disease and identifies biomarkers predictive of disease.NEW & NOTEWORTHY In a chronic model of smoking-induced cardiovascular disease, we define underlying mechanisms of smoking-induced vascular endothelial dysfunction (VED). Smoking exposure triggered VED and hypertension and led to vascular macrophage infiltration with concomitant increase in superoxide and NADPH oxidase levels as early as 16 wk of exposure. This oxidative stress was accompanied by tetrahydrobiopterin depletion, resulting in endothelial nitric oxide synthase uncoupling with further superoxide generation triggering a vicious cycle of oxidative stress and VED.
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Moustafa GA, El-Mahdy MA, Ismail RS, Mansour AM. Thymoquinone Protects Against Cigarette Smoke Extract‐induced Vascular Dysfunction Through Inhibition of the RhoA/Rho‐Kinase Signaling Pathway. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.08873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Jensen PS, Gulati IK, Shubert TR, Sitaram S, Sivalingam M, Hasenstab KA, El-Mahdy MA, Jadcherla SR. Pharyngeal stimulus-induced reflexes are impaired in infants with perinatal asphyxia: Does maturation modify? Neurogastroenterol Motil 2017; 29:10.1111/nmo.13039. [PMID: 28256028 PMCID: PMC5466491 DOI: 10.1111/nmo.13039] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 01/09/2017] [Indexed: 12/31/2022]
Abstract
BACKGROUND Development of pharyngo-esophageal protective reflexes among infants with hypoxic ischemic encephalopathy (HIE) is unclear. Our aim was to distinguish these reflexes from controls and examine the maturational changes in HIE infants. METHODS We evaluated 14 HIE infants (seven males) at 41.4±0.6 (HIE Time-1) and 46.5±0.6 (HIE Time-2) weeks postmenstrual age (PMA). Seven controls (three males) were evaluated at 43.5±1.3 weeks PMA. Graded pharyngeal stimulation with liquids (0.1, 0.3, 0.5 mL in triplicate) concurrent with high-resolution manometry was used to analyze sensory-motor components of pharyngeal reflexive swallowing (PRS), upper esophageal sphincter (UES), contractile reflex (PUCR), and esophageal body characteristics. Linear mixed and generalized estimating equation models were used for comparison among groups. KEY RESULTS Compared to controls, HIE infants (Time-1 and Time-2) exhibited decreased number of pharyngeal peaks and latency to terminal swallow. HIE Time-1 infants showed increased UES resting tone and distal latency, compared to controls and HIE Time-2. Contractile vigor was increasingly abnormal during maturation, compared to healthy controls. Threshold volumes and frequency distribution of primary responses (PRS: PUCR: None) were not significant among all groups. CONCLUSIONS & INFERENCES Compared to controls, HIE infants display significant hypertonicity of skeletal muscle components, impairment of pharyngeal provocation-induced reflexes and smooth muscle contractile vigor, reflecting poor propagation with maturation. These mechanisms may be responsible for inadequate clearance of secretions, ascending refluxate, and oropharyngeal bolus in HIE infants.
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Liu X, El-Mahdy MA, Boslett J, Varadharaj S, Hemann C, Abdelghany TM, Ismail RS, Little SC, Zhou D, Thuy LTT, Kawada N, Zweier JL. Cytoglobin regulates blood pressure and vascular tone through nitric oxide metabolism in the vascular wall. Nat Commun 2017; 8:14807. [PMID: 28393874 PMCID: PMC5394235 DOI: 10.1038/ncomms14807] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 02/01/2017] [Indexed: 12/19/2022] Open
Abstract
The identity of the specific nitric oxide dioxygenase (NOD) that serves as the main in vivo regulator of O2-dependent NO degradation in smooth muscle remains elusive. Cytoglobin (Cygb) is a recently discovered globin expressed in fibroblasts and smooth muscle cells with unknown function. Cygb, coupled with a cellular reducing system, efficiently regulates the rate of NO consumption by metabolizing NO in an O2-dependent manner with decreased NO consumption in physiological hypoxia. Here we show that Cygb is a major regulator of NO degradation and cardiovascular tone. Knockout of Cygb greatly prolongs NO decay, increases vascular relaxation, and lowers blood pressure and systemic vascular resistance. We further demonstrate that downregulation of Cygb prevents angiotensin-mediated hypertension. Thus, Cygb has a critical role in the regulation of vascular tone and disease. We suggest that modulation of the expression and NOD activity of Cygb represents a strategy for the treatment of cardiovascular disease. The gaseous signalling molecule nitric oxide regulates vascular tone. Here, the authors show that nitric oxide is degraded by the enzyme cytoglobin in the vascular wall, and that mice lacking cytoglobin have reduced blood pressure and are less sensitive to angiotensin-mediated hypertension.
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Kashou NH, Dar IA, El-Mahdy MA, Pluto C, Smith M, Gulati IK, Lo W, Jadcherla SR. Brain Lesions among Orally Fed and Gastrostomy-Fed Dysphagic Preterm Infants: Can Routine Qualitative or Volumetric Quantitative Magnetic Resonance Imaging Predict Feeding Outcomes? Front Pediatr 2017; 5:73. [PMID: 28443270 PMCID: PMC5385332 DOI: 10.3389/fped.2017.00073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 03/24/2017] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION The usefulness of qualitative or quantitative volumetric magnetic resonance imaging (MRI) in early detection of brain structural changes and prediction of adverse outcomes in neonatal illnesses warrants further investigation. Our aim was to correlate certain brain injuries and the brain volume of feeding-related cortical and subcortical regions with feeding method at discharge among preterm dysphagic infants. MATERIALS AND METHODS Using a retrospective observational study design, we examined MRI data among 43 (22 male; born at 31.5 ± 0.8 week gestation) infants who went home on oral feeding or gastrostomy feeding (G-tube). MRI scans were segmented, and volumes of brainstem, cerebellum, cerebrum, basal ganglia, thalamus, and vermis were quantified, and correlations were made with discharge feeding outcomes. Chi-squared tests were used to evaluate MRI findings vs. feeding outcomes. ANCOVA was performed on the regression model to measure the association of maturity and brain volume between groups. RESULTS Out of 43 infants, 44% were oral-fed and 56% were G-tube fed at hospital discharge (but not at time of the study). There was no relationship between qualitative brain lesions and feeding outcomes. Volumetric analysis revealed that cerebellum was greater (p < 0.05) in G-tube fed infants, whereas cerebrum volume was greater (p < 0.05) in oral-fed infants. Other brain regions did not show volumetric differences between groups. CONCLUSION This study concludes that neither qualitative nor quantitative volumetric MRI findings correlate with feeding outcomes. Understanding the complexity of swallowing and feeding difficulties in infants warrants a comprehensive and in-depth functional neurological assessment.
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Li H, Hemann C, Abdelghany TM, El-Mahdy MA, Zweier JL. Characterization of the mechanism and magnitude of cytoglobin-mediated nitrite reduction and nitric oxide generation under anaerobic conditions. J Biol Chem 2012; 287:36623-33. [PMID: 22896706 DOI: 10.1074/jbc.m112.342378] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytoglobin (Cygb) is a recently discovered cytoplasmic heme-binding globin. Although multiple hemeproteins have been reported to function as nitrite reductases in mammalian cells, it is unknown whether Cygb can also reduce nitrite to nitric oxide (NO). The mechanism, magnitude, and quantitative importance of Cygb-mediated nitrite reduction in tissues have not been reported. To investigate this pathway and its quantitative importance, EPR spectroscopy, spectrophotometric measurements, and chemiluminescence NO analyzer studies were performed. Under anaerobic conditions, mixing nitrite with ferrous-Cygb triggered NO formation that was trapped and detected using EPR spin trapping. Spectrophotometric studies revealed that nitrite binding to ferrous-Cygb is followed by formation of ferric-Cygb and NO. The kinetics and magnitude of Cygb-mediated NO formation were characterized. It was observed that Cygb-mediated NO generation increased linearly with the increase of nitrite concentration under anaerobic conditions. This Cygb-mediated NO production greatly increased with acidosis and near-anoxia as occur in ischemic conditions. With the addition of nitrite, soluble guanylyl cyclase activation was significantly higher in normal smooth muscle cells compared with Cygb knocked down cells with Cygb accounting for ∼40% of the activation in control cells and ∼60% in cells subjected to hypoxia for 48 h. Overall, these studies show that Cygb-mediated nitrite reduction can play an important role in NO generation and soluble guanylyl cyclase activation under hypoxic conditions, with this process regulated by pH, oxygen tension, nitrite concentration, and the redox state of the cells.
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El-Mahdy MA, Abdelghany TM, Hemann C, Varadharaj S, Esmat A, El-Sherbiny GA, Zweier JL. Involvement of the Endothelial Nitric Oxide Pathway and Leukocyte Infiltration in Secondhand Smoke Exposure‐Induced Vascular Endothelial Dysfunction and Hypertension. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.866.7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Esmat A, Khalifa AE, El-Demerdash E, Abdel-naim AB, El-Mahdy MA, Zweier JL. Dichloroacetonitrile Induces Protein Modifications in Cortical Astrocyte Cell Line CTX‐TNA2 and Alterations in Fetal Mouse Brain. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.674.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Zweier JL, Tewari AK, El-Mahdy MA, Abdelghany TM, Hemann C, El-Sherbiny GA. Potential Proteomic Biomarkers of Secondhand Smoking‐ Induced Cardiovascular Disease. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.874.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Caia GL, Efimova OV, Velayutham M, El-Mahdy MA, Abdelghany TM, Kesselring E, Petryakov S, Sun Z, Samouilov A, Zweier JL. Organ specific mapping of in vivo redox state in control and cigarette smoke-exposed mice using EPR/NMR co-imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 216:21-7. [PMID: 22296801 PMCID: PMC4073597 DOI: 10.1016/j.jmr.2011.10.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/25/2011] [Accepted: 10/25/2011] [Indexed: 05/31/2023]
Abstract
In vivo mapping of alterations in redox status is important for understanding organ specific pathology and disease. While electron paramagnetic resonance imaging (EPRI) enables spatial mapping of free radicals, it does not provide anatomic visualization of the body. Proton MRI is well suited to provide anatomical visualization. We applied EPR/NMR co-imaging instrumentation to map and monitor the redox state of living mice under normal or oxidative stress conditions induced by secondhand cigarette smoke (SHS) exposure. A hybrid co-imaging instrument, EPRI (1.2 GHz)/proton MRI (16.18 MHz), suitable for whole-body co-imaging of mice was utilized with common magnet and gradients along with dual EPR/NMR resonators that enable co-imaging without sample movement. The metabolism of the nitroxide probe, 3-carbamoyl-proxyl (3-CP), was used to map the redox state of control and SHS-exposed mice. Co-imaging allowed precise 3D mapping of radical distribution and reduction in major organs such as the heart, lungs, liver, bladder and kidneys. Reductive metabolism was markedly decreased in SHS-exposed mice and EPR/NMR co-imaging allowed quantitative assessment of this throughout the body. Thus, in vivo EPR/NMR co-imaging enables in vivo organ specific mapping of free radical metabolism and redox stress and the alterations that occur in the pathogenesis of disease.
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Tewari AK, Popova-Butler A, El-Mahdy MA, Zweier JL. Identification of differentially expressed proteins in blood plasma of control and cigarette smoke-exposed mice by 2-D DIGE/MS. Proteomics Clin Appl 2011. [DOI: 10.1002/prca.201190078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Tewari AK, Popova-Butler A, El-Mahdy MA, Zweier JL. Identification of differentially expressed proteins in blood plasma of control and cigarette smoke-exposed mice by 2-D DIGE/MS. Proteomics 2011; 11:2051-62. [PMID: 21500341 DOI: 10.1002/pmic.201000159] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 02/04/2011] [Accepted: 02/11/2011] [Indexed: 01/23/2023]
Abstract
Cigarette smoke exposure is known to induce obstructive lung disease and several cardiovascular disease states in humans and also in animal models. Smoking leads to oxidative stress and inflammation that are important in triggering pulmonary and cardiovascular disease. The objective of the current study was to quantify differences in expression levels of plasma proteins of cigarette smoke -exposed and control mice, at the time of disease onset, and identify these proteins for use as potential biomarkers of the onset of smoking-induced disease. We utilized 2-D DIGE/MS to characterize these proteomic changes. 2-D DIGE of plasma samples identified 11 differentially expressed proteins in cigarette smoke -exposed mice. From these 11 proteins, 9 were downregulated and 2 were upregulated. The proteins identified are involved in vascular function, coagulation, metabolism and immune function. Among these, the alterations in fibrinogen (2.2-fold decrease), α-1-antitrypsin (1.8-fold increase) and arginase (4.5-fold decrease) are of particular interest since these have been directly linked to cardiovascular and lung pathology. Differences in expression levels of these proteins were also confirmed by immunoblotting. Thus, we observe that chronic cigarette smoke exposure in mice leads to prominent changes in the protein expression profile of blood plasma and these changes in turn can potentially serve as markers predictive of the onset and progression of cardiovascular and pulmonary disease.
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Talukder MAH, Johnson WM, Varadharaj S, Lian J, Kearns PN, El-Mahdy MA, Liu X, Zweier JL. Chronic cigarette smoking causes hypertension, increased oxidative stress, impaired NO bioavailability, endothelial dysfunction, and cardiac remodeling in mice. Am J Physiol Heart Circ Physiol 2011; 300:H388-96. [PMID: 21057039 PMCID: PMC3023256 DOI: 10.1152/ajpheart.00868.2010] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 11/02/2010] [Indexed: 11/22/2022]
Abstract
Cigarette smoking is a major independent risk factor for cardiovascular disease. While the association between chronic smoking and cardiovascular disease is well established, the underlying mechanisms are incompletely understood, partly due to the lack of adequate in vivo animal models. Here, we report a mouse model of chronic smoking-induced cardiovascular pathology. Male C57BL/6J mice were exposed to whole body mainstream cigarette smoke (CS) using a SCIREQ "InExpose" smoking system (48 min/day, 5 days/wk) for 16 or 32 wk. Age-matched, air-exposed mice served as nonsmoking controls. Blood pressure was measured, and cardiac MRI was performed. In vitro vascular ring and isolated heart experiments were performed to measure vascular reactivity and cardiac function. Blood from control and smoking mice was studied for the nitric oxide (NO) decay rate and reactive oxygen species (ROS) generation. With 32 wk of CS exposure, mice had significantly less body weight gain and markedly higher blood pressure. At 32 wk of CS exposure, ACh-induced vasorelaxation was significantly shifted to the right and downward, left ventricular mass was significantly larger along with an increased heart-to-body weight ratio, in vitro cardiac function tended to be impaired with high afterload, white blood cells had significantly higher ROS generation, and the blood NO decay rate was significantly faster. Thus, smoking led to blunted weight gain, hypertension, endothelial dysfunction, leukocyte activation with ROS generation, decreased NO bioavailability, and mild cardiac hypertrophy in mice that were not otherwise predisposed to disease. This mouse model is a useful tool to enable further elucidation of the molecular and cellular mechanisms of smoking-induced cardiovascular diseases.
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