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Elajaili HB, Woodcock LB, Hovey TA, Rinard GA, DeGraw S, Canny A, Dee NM, Kao JPY, Nozik ES, Eaton SS, Eaton GR. Imaging Reactive Oxygen Radicals in Excised Mouse Lung Trapped by Reaction with Hydroxylamine Probes Using 1 GHz Rapid Scan Electron Paramagnetic Resonance. Mol Imaging Biol 2023:10.1007/s11307-023-01860-3. [PMID: 37821714 PMCID: PMC11006821 DOI: 10.1007/s11307-023-01860-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 10/13/2023]
Abstract
PURPOSE Oxidative stress is proposed to be critical in acute lung disease, but methods to monitor radicals in lungs are lacking. Our goal is to develop low-frequency electron paramagnetic resonance (EPR) methods to monitor radicals that contribute to the disease. PROCEDURES Free radicals generated in a lipopolysaccharide-induced mouse model of acute respiratory distress syndrome reacted with cyclic hydroxylamines CPH (1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine hydrochloride) and DCP-AM-H (4-acetoxymethoxycarbonyl-1-hydroxy-2,2,5,5-tetramethylpyrrolidine-3-carboxylic acid), which were converted into the corresponding nitroxide radicals, CP• and DCP•. The EPR signals of the nitroxide radicals in excised lungs were imaged with a 1 GHz EPR spectrometer/imager that employs rapid scan technology. RESULTS The small numbers of nitroxides formed by reaction of the hydroxylamine with superoxide result in low signal-to-noise in the spectra and images. However, since the spectral properties of the nitroxides are known, we can use prior knowledge of the line shape and hyperfine splitting to fit the noisy data, yielding well-defined spectra and images. Two-dimensional spectral-spatial images are shown for lung samples containing (4.5 ± 0.5) ×1014 CP• and (9.9 ± 1.0) ×1014 DCP• nitroxide spins. These results suggest that a probe that accumulates in cells gives a stronger nitroxide signal than a probe that is more easily washed out of cells. CONCLUSION The nitroxide radicals in excised mouse lungs formed by reaction with hydroxylamine probes CPH and DCP-AM-H can be imaged at 1 GHz.
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Affiliation(s)
- Hanan B Elajaili
- Cardiovascular Pulmonary Research Laboratories and Pediatric Critical Care Medicine, University of Colorado Anschutz Medical Campus, 12700 E. 19th Ave., B131, Aurora, CO, 80045, USA
| | - Lukas B Woodcock
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA
| | - Tanden A Hovey
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA
| | - George A Rinard
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA
| | - Samuel DeGraw
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA
| | - Autumn Canny
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA
| | - Nathan M Dee
- Cardiovascular Pulmonary Research Laboratories and Pediatric Critical Care Medicine, University of Colorado Anschutz Medical Campus, 12700 E. 19th Ave., B131, Aurora, CO, 80045, USA
| | - Joseph P Y Kao
- Center for Biomedical Engineering and Technology and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Eva S Nozik
- Cardiovascular Pulmonary Research Laboratories and Pediatric Critical Care Medicine, University of Colorado Anschutz Medical Campus, 12700 E. 19th Ave., B131, Aurora, CO, 80045, USA
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA.
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Elajaili HB, Dee NM, Dikalov SI, Kao JPY, Nozik ES. Use of Electron Paramagnetic Resonance (EPR) to Evaluate Redox Status in a Preclinical Model of Acute Lung Injury. Mol Imaging Biol 2023:10.1007/s11307-023-01826-5. [PMID: 37193807 PMCID: PMC10188229 DOI: 10.1007/s11307-023-01826-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 05/03/2023] [Accepted: 05/08/2023] [Indexed: 05/18/2023]
Abstract
PURPOSE Patients with hyper- vs. hypo-inflammatory subphenotypes of acute respiratory distress syndrome (ARDS) exhibit different clinical outcomes. Inflammation increases the production of reactive oxygen species (ROS) and increased ROS contributes to the severity of illness. Our long-term goal is to develop electron paramagnetic resonance (EPR) imaging of lungs in vivo to precisely measure superoxide production in ARDS in real time. As a first step, this requires the development of in vivo EPR methods for quantifying superoxide generation in the lung during injury, and testing if such superoxide measurements can differentiate between susceptible and protected mouse strains. PROCEDURES In WT mice, mice lacking total body extracellular superoxide dismutase (EC-SOD) (KO), or mice overexpressing lung EC-SOD (Tg), lung injury was induced with intraperitoneal (IP) lipopolysaccharide (LPS) (10 mg/kg). At 24 h after LPS treatment, mice were injected with the cyclic hydroxylamines 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine hydrochloride (CPH) or 4-acetoxymethoxycarbonyl-1-hydroxy-2,2,5,5-tetramethylpyrrolidine-3-carboxylic acid (DCP-AM-H) probes to detect, respectively, cellular and mitochondrial ROS - specifically superoxide. Several probe delivery strategies were tested. Lung tissue was collected up to one hour after probe administration and assayed by EPR. RESULTS As measured by X-band EPR, cellular and mitochondrial superoxide increased in the lungs of LPS-treated mice compared to control. Lung cellular superoxide was increased in EC-SOD KO mice and decreased in EC-SOD Tg mice compared to WT. We also validated an intratracheal (IT) delivery method, which enhanced the lung signal for both spin probes compared to IP administration. CONCLUSIONS We have developed protocols for delivering EPR spin probes in vivo, allowing detection of cellular and mitochondrial superoxide in lung injury by EPR. Superoxide measurements by EPR could differentiate mice with and without lung injury, as well as mouse strains with different disease susceptibilities. We expect these protocols to capture real-time superoxide production and enable evaluation of lung EPR imaging as a potential clinical tool for subphenotyping ARDS patients based on redox status.
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Affiliation(s)
- Hanan B Elajaili
- Pediatric Critical Care Medicine, University of Colorado Anschutz Medical Campus, 12700 E. 19th Ave., B131, Aurora, CO, 80045, USA
| | - Nathan M Dee
- Pediatric Critical Care Medicine, University of Colorado Anschutz Medical Campus, 12700 E. 19th Ave., B131, Aurora, CO, 80045, USA
| | - Sergey I Dikalov
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Joseph P Y Kao
- Center for Biomedical Engineering and Technology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Eva S Nozik
- Pediatric Critical Care Medicine, University of Colorado Anschutz Medical Campus, 12700 E. 19th Ave., B131, Aurora, CO, 80045, USA.
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Madhavan K, Balakrishnan I, Lakshmanachetty S, Pierce A, Sanford B, Fosmire S, Elajaili HB, Walker F, Wang D, Nozik ES, Mitra SS, Dahl NA, Vibhakar R, Venkataraman S. Venetoclax cooperates with ionizing radiation to attenuate Diffuse Midline Glioma tumor growth. Clin Cancer Res 2022; 28:2409-2424. [PMID: 35344040 DOI: 10.1158/1078-0432.ccr-21-4002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/10/2022] [Accepted: 03/24/2022] [Indexed: 11/16/2022]
Abstract
PURPOSE Tumor relapse after radiation therapy (RT) is a major hurdle in treating pediatric H3K27M-mutant diffuse midline gliomas (DMGs). RT-induced stress increases association of BCL2 family of proteins with BH3 pro-apoptotic activators preventing apoptosis. We hypothesized that inhibition of RT-induced BCL2 with a clinically relevant inhibitor, venetoclax, will block BCL2 activity leading to increased apoptosis. BCL2 has never been implicated in DMG as a RT-induced resistant mechanism. EXPERIMENTAL DESIGN We performed an integrated genomic analysis to determine genes responsible for radioresistance and a targeted drug screen to identify drugs that synergize with radiation in DMG. Effect of venetoclax on radiation-na�ve and 6Gy radiation on cells was evaluated by studying cell death, changes in BCL2 phosphorylation, reactive oxygen species (ROS), and apoptosis, as well as BCL2 association with BH3 apoptosis initiators. The efficacy of combining venetoclax with radiation was evaluated in vivo using orthotopic xenograft models. RESULTS BCL2 was identified as a key regulator of tumor growth after radiation in DMGs. Radiation sensitizes DMGs to venetoclax treatment independent of p53 status. Venetoclax as a monotherapy was not cytotoxic to DMG cells. Post-radiation venetoclax treatment significantly increased cell death, reduced BCL2-BIM association and augmented mitochondrial ROS leading to increased apoptosis. Combining venetoclax with RT significantly enhanced the survival of mice with DMG tumors. CONCLUSIONS This study shows that venetoclax impedes the anti-apoptotic function of radiation-induced BCL2 in DMG leading to increased apoptosis. Results from these pre-clinical studies demonstrate the potential use of the BCL2 inhibitor, venetoclax, combined with RT for pediatric DMG.
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Affiliation(s)
- Krishna Madhavan
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | | | | | - Angela Pierce
- University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Bridget Sanford
- University of Colorado Anschutz Medical Campus, United States
| | - Susan Fosmire
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Hanan B Elajaili
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Faye Walker
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Dong Wang
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Eva S Nozik
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Siddhartha S Mitra
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Nathan A Dahl
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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Pires da Silva J, Garcia AM, Miyano CA, Sparagna GC, Jonscher RL, Elajaili HB, Sucharov CC. Abstract P372: Serum From Pediatric Dilated Cardiomyopathy Patients Promotes Dysregulation Of Cardiolipin Biosynthesis And Mitochondrial Dysfunction In Primary Cardiomyocytes. Circ Res 2021. [DOI: 10.1161/res.129.suppl_1.p372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pediatric dilated cardiomyopathy (DCM) is a devastating and poorly understood disease with most clinical treatment paradigms extrapolated from the adult population. Our studies have demonstrated that aspects of metabolism and mitochondrial function are dysregulated in pediatric DCM hearts. Cardiolipin (CL), a unique phospholipid in the inner mitochondrial membrane, is essential for optimal mitochondrial function and was shown to be dysregulated in both the failing adult and pediatric human heart. The objective of this study is to investigate if serum circulating factors from pediatric DCM patients can remodel CL resulting in mitochondrial dysfunction
in vitro
, similar to what is observed in the failing pediatric heart.
Using a novel
in vitro
model that consists of treating neonatal rat ventricular myocytes (NRVMs) with serum from pediatric DCM patients or from non-failing (NF) healthy controls, mitochondrial respiration was assessed using the Agilent Seahorse, and reactive oxygen species (ROS) was assessed using Electron Paramagnetic Resonance Spectroscopy. Relative mitochondrial DNA (mtDNA) copy number was determined by qPCR and expression of enzymes involved in CL biosynthesis and remodeling were analyzed using RT-qPCR. Mass-spectrometry was used to quantitate total and specific CL species and to investigate the metabolite composition of NRVMs treated with NF or DCM serum.
While mitochondrial ROS and mtDNA copy number were not significantly altered, we show that DCM serum decreases mitochondrial function, which is associated with alterations in CL content and composition and the downregulation of enzymes implicated in CL biosynthesis and remodeling. Analysis of metabolite content showed an alteration of pathways involved in fatty acid metabolism, mitochondrial biogenesis and regulation of β-oxidation by the transcription factor PPARα.
In conclusion, pediatric DCM serum circulating factors can promote CL remodeling resulting mitochondrial dysfunction in primary cardiomyocytes. These findings suggest that CL could be a novel therapeutic target for this particular population.
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Elajaili HB, Hernandez-Lagunas L, Ranguelova K, Dikalov S, Nozik-Grayck E. Use of Electron Paramagnetic Resonance in Biological Samples at Ambient Temperature and 77 K. J Vis Exp 2019. [PMID: 30688300 DOI: 10.3791/58461] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The accurate and specific detection of reactive oxygen species (ROS) in different cellular and tissue compartments is essential to the study of redox-regulated signaling in biological settings. Electron paramagnetic resonance spectroscopy (EPR) is the only direct method to assess free radicals unambiguously. Its advantage is that it detects physiologic levels of specific species with a high specificity, but it does require specialized technology, careful sample preparation, and appropriate controls to ensure accurate interpretation of the data. Cyclic hydroxylamine spin probes react selectively with superoxide or other radicals to generate a nitroxide signal that can be quantified by EPR spectroscopy. Cell-permeable spin probes and spin probes designed to accumulate rapidly in the mitochondria allow for the determination of superoxide concentration in different cellular compartments. In cultured cells, the use of cell permeable 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH) along with and without cell-impermeable superoxide dismutase (SOD) pretreatment, or use of cell-permeable PEG-SOD, allows for the differentiation of extracellular from cytosolic superoxide. The mitochondrial 1-hydroxy-4-[2-triphenylphosphonio)-acetamido]-2,2,6,6-tetramethyl-piperidine,1-hydroxy-2,2,6,6-tetramethyl-4-[2-(triphenylphosphonio)acetamido] piperidinium dichloride (mito-TEMPO-H) allows for measurement of mitochondrial ROS (predominantly superoxide). Spin probes and EPR spectroscopy can also be applied to in vivo models. Superoxide can be detected in extracellular fluids such as blood and alveolar fluid, as well as tissues such as lung tissue. Several methods are presented to process and store tissue for EPR measurements and deliver intravenous 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CPH) spin probe in vivo. While measurements can be performed at room temperature, samples obtained from in vitro and in vivo models can also be stored at -80 °C and analyzed by EPR at 77 K. The samples can be stored in specialized tubing stable at -80 °C and run at 77 K to enable a practical, efficient, and reproducible method that facilitates storing and transferring samples.
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Affiliation(s)
- Hanan B Elajaili
- Cardiovascular Pulmonary Research Laboratories and Pediatric Critical Care Medicine, Department of Pediatrics, University of Colorado Anschutz Medical Campus
| | - Laura Hernandez-Lagunas
- Cardiovascular Pulmonary Research Laboratories and Pediatric Critical Care Medicine, Department of Pediatrics, University of Colorado Anschutz Medical Campus
| | | | - Sergey Dikalov
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center
| | - Eva Nozik-Grayck
- Cardiovascular Pulmonary Research Laboratories and Pediatric Critical Care Medicine, Department of Pediatrics, University of Colorado Anschutz Medical Campus;
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Elajaili HB, Biller JR, Tseitlin M, Dhimitruka I, Khramtsov VV, Eaton SS, Eaton GR. Electron spin relaxation times and rapid scan EPR imaging of pH-sensitive amino-substituted trityl radicals. Magn Reson Chem 2015; 53:280-4. [PMID: 25504559 PMCID: PMC4374029 DOI: 10.1002/mrc.4193] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/16/2014] [Accepted: 11/03/2014] [Indexed: 05/26/2023]
Abstract
Carboxy-substituted trityl (triarylmethyl) radicals are valuable in vivo probes because of their stability, narrow lines, and sensitivity of their spectroscopic properties to oxygen. Amino-substituted trityl radicals have the potential to monitor pH in vivo, and the suitability for this application depends on spectral properties. Electron spin relaxation times T1 and T2 were measured at X-band for the protonated and deprotonated forms of two amino-substituted triarylmethyl radicals. Comparison with relaxation times for carboxy-substituted triarylmethyl radicals shows that T1 exhibits little dependence on protonation or the nature of the substituent, which makes it useful for measuring O2 concentration, independent of pH. Insensitivity of T1 to changes in substituents is consistent with the assignment of the dominant contribution to spin lattice relaxation as a local mode that involves primarily atoms in the carbon and sulfur core. Values of T2 vary substantially with pH and the nature of the aryl group substituent, reflecting a range of dynamic processes. The narrow spectral widths for the amino-substituted triarylmethyl radicals facilitate spectral-spatial rapid scan electron paramagnetic resonance imaging, which was demonstrated with a phantom. The dependence of hyperfine splittings patterns on pH is revealed in spectral slices through the image.
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Affiliation(s)
- Hanan B Elajaili
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80210, USA
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Elajaili HB, Biller JR, Eaton SS, Eaton GR. Frequency dependence of electron spin-lattice relaxation for semiquinones in alcohol solutions. J Magn Reson 2014; 247:81-87. [PMID: 25261741 PMCID: PMC4224960 DOI: 10.1016/j.jmr.2014.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 08/06/2014] [Accepted: 08/28/2014] [Indexed: 05/31/2023]
Abstract
The spin-lattice relaxation rates at 293 K for three anionic semiquinones (2,5-di-t-butyl-1,4-benzosemiquinone, 2,6-di-t-butyl-1,4-benzosemiquinone, and 2,3,5,6-tetramethoxy-1,4-benzosemiquinone) were studied at up to 8 frequencies between 250 MHz and 34 GHz in ethanol or methanol solution containing high concentrations of OH(-). The relaxation rates are about a factor of 2 faster at lower frequencies than at 9 or 34 GHz. However, in perdeuterated alcohols the relaxation rates exhibit little frequency dependence, which demonstrates that the dominant frequency-dependent contribution to relaxation is modulation of dipolar interactions with solvent nuclei. The relaxation rates were modeled as the sum of two frequency-independent contributions (spin rotation and a local mode) and two frequency-dependent contributions (modulation of dipolar interaction with solvent nuclei and a much smaller contribution from modulation of g anisotropy). The correlation time for modulation of the interaction with solvent nuclei is longer than the tumbling correlation time of the semiquinone and is consistent with hydrogen bonding of the alcohol to the oxygen atoms of the semiquinones.
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Affiliation(s)
- Hanan B Elajaili
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | - Joshua R Biller
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA.
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