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Windham IA, Powers AE, Ragusa JV, Wallace ED, Zanellati MC, Williams VH, Wagner CH, White KK, Cohen S. APOE traffics to astrocyte lipid droplets and modulates triglyceride saturation and droplet size. J Cell Biol 2024; 223:e202305003. [PMID: 38334983 PMCID: PMC10857907 DOI: 10.1083/jcb.202305003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 12/01/2023] [Accepted: 01/08/2024] [Indexed: 02/10/2024] Open
Abstract
The E4 variant of APOE strongly predisposes individuals to late-onset Alzheimer's disease. We demonstrate that in response to lipogenesis, apolipoprotein E (APOE) in astrocytes can avoid translocation into the endoplasmic reticulum (ER) lumen and traffic to lipid droplets (LDs) via membrane bridges at ER-LD contacts. APOE knockdown promotes fewer, larger LDs after a fatty acid pulse, which contain more unsaturated triglyceride after fatty acid pulse-chase. This LD size phenotype was rescued by chimeric APOE that targets only LDs. Like APOE depletion, APOE4-expressing astrocytes form a small number of large LDs enriched in unsaturated triglyceride. Additionally, the LDs in APOE4 cells exhibit impaired turnover and increased sensitivity to lipid peroxidation. Our data indicate that APOE plays a previously unrecognized role as an LD surface protein that regulates LD size and composition. APOE4 causes aberrant LD composition and morphology. Our study contributes to accumulating evidence that APOE4 astrocytes with large, unsaturated LDs are sensitized to lipid peroxidation, which could contribute to Alzheimer's disease risk.
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Affiliation(s)
- Ian A. Windham
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alex E. Powers
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joey V. Ragusa
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - E. Diane Wallace
- Mass Spectrometry Core Laboratory, Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Maria Clara Zanellati
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Victoria H. Williams
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Colby H. Wagner
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kristen K. White
- Microscopy Services Laboratory, Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah Cohen
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Yadav-Samudrala BJ, Gorman BL, Barmada KM, Ravula HP, Huguely CJ, Wallace ED, Peace MR, Poklis JL, Jiang W, Fitting S. Effects of acute cannabidiol on behavior and the endocannabinoid system in HIV-1 Tat transgenic female and male mice. Front Neurosci 2024; 18:1358555. [PMID: 38505774 PMCID: PMC10949733 DOI: 10.3389/fnins.2024.1358555] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/12/2024] [Indexed: 03/21/2024] Open
Abstract
Background Some evidence suggests that cannabidiol (CBD) has potential to help alleviate HIV symptoms due to its antioxidant and anti-inflammatory properties. Here we examined acute CBD effects on various behaviors and the endocannabinoid system in HIV Tat transgenic mice. Methods Tat transgenic mice (female/male) were injected with CBD (3, 10, 30 mg/kg) and assessed for antinociception, activity, coordination, anxiety-like behavior, and recognition memory. Brains were taken to quantify endocannabinoids, cannabinoid receptors, and cannabinoid catabolic enzymes. Additionally, CBD and metabolite 7-hydroxy-CBD were quantified in the plasma and cortex. Results Tat decreased supraspinal-related nociception and locomotion. CBD and sex had little to no effects on any of the behavioral measures. For the endocannabinoid system male sex was associated with elevated concentration of the proinflammatory metabolite arachidonic acid in various CNS regions, including the cerebellum that also showed higher FAAH expression levels for Tat(+) males. GPR55 expression levels in the striatum and cerebellum were higher for females compared to males. CBD metabolism was altered by sex and Tat expression. Conclusion Findings indicate that acute CBD effects are not altered by HIV Tat, and acute CBD has no to minimal effects on behavior and the endocannabinoid system.
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Affiliation(s)
- Barkha J. Yadav-Samudrala
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Benjamin L. Gorman
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Karenna M. Barmada
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Havilah P. Ravula
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Caitlin J. Huguely
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - E. Diane Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Michelle R. Peace
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States
| | - Justin L. Poklis
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States
| | - Wei Jiang
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, United States
- Division of Infectious Diseases, Department of Medicine, Medical University of South Carolina, Charleston, SC, United States
| | - Sylvia Fitting
- Department of Psychology and Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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Yadav-Samudrala BJ, Gorman BL, Dodson H, Ramineni S, Wallace ED, Peace MR, Poklis JL, Jiang W, Fitting S. Effects of acute Δ 9-tetrahydrocannabinol on behavior and the endocannabinoid system in HIV-1 Tat transgenic female and male mice. Brain Res 2024; 1822:148638. [PMID: 37858856 PMCID: PMC10873064 DOI: 10.1016/j.brainres.2023.148638] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/22/2023] [Accepted: 10/16/2023] [Indexed: 10/21/2023]
Abstract
Cannabis use is highly prevalent especially among people living with HIV (PLWH). Activation of the anti-inflammatory and neuroprotective endocannabinoid system by phytocannabinoids, i.e. Δ9-tetrahydrocannabinol (THC), has been proposed to reduce HIV symptoms. However, THC's effects on HIV-related memory deficits are unclear. Using HIV-1 Tat transgenic mice, the current study investigates acute THC effects on various behavioral outcomes and the endocannabinoid system. For the rodent tetrad model, THC doses (1, 3, 10 mg/kg) induced known antinociceptive effects, with Tat induction increasing antinociceptive THC effects at 3 and 10 mg/kg doses. Only minor or no effects were noted for acute THC on body temperature, locomotor activity, and coordination. Increased anxiety-like behavior was found for females compared to males, but acute THC had no effect on anxiety. Object recognition memory was diminished by acute THC in Tat(-) females but not Tat(+) females, without affecting males. The endocannabinoid system and related lipids were not affected by acute THC, except for THC-induced decreases in CB1R protein expression levels in the spinal cord of Tat(-) mice. Female sex and Tat induction was associated with elevated 2-AG, AEA, AA, CB1R, CB2R, FAAH and/or MAGL expression in various brain regions. Further, AEA levels in the prefrontal cortex of Tat(+) females were negatively associated with object recognition memory. Overall, findings indicate that acute THC exerts differential effects on antinociception and memory, dependent on sex and HIV Tat expression, potentially in relation to an altered endocannabinoid system, which may be of relevance in view of potential cannabis-based treatment options for PLWH.
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Affiliation(s)
- Barkha J Yadav-Samudrala
- Department of Psychology & Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Benjamin L Gorman
- Department of Psychology & Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Hailey Dodson
- Department of Psychology & Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Shreya Ramineni
- Department of Psychology & Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - E Diane Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Michelle R Peace
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Justin L Poklis
- Department of Forensic Science, Virginia Commonwealth University, Richmond, VA 23284, USA
| | - Wei Jiang
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC 29425, USA; Division of Infectious Diseases, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Sylvia Fitting
- Department of Psychology & Neuroscience, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Kim ES, Casey JG, Tao BS, Mansur A, Mathiyalagan N, Wallace ED, Ehrmann BM, Gupta VA. Intrinsic and extrinsic regulation of rhabdomyolysis susceptibility by Tango2. Dis Model Mech 2023; 16:dmm050092. [PMID: 37577943 PMCID: PMC10499024 DOI: 10.1242/dmm.050092] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 08/09/2023] [Indexed: 08/15/2023] Open
Abstract
Rhabdomyolysis is a clinical emergency characterized by severe muscle damage, resulting in the release of intracellular muscle components, which leads to myoglobinuria and, in severe cases, acute kidney failure. Rhabdomyolysis is caused by genetic factors linked to increased disease susceptibility in response to extrinsic triggers. Recessive mutations in TANGO2 result in episodic rhabdomyolysis, metabolic crises, encephalopathy and cardiac arrhythmia. The underlying mechanism contributing to disease onset in response to specific triggers remains unclear. To address these challenges, we created a zebrafish model of Tango2 deficiency. Here, we demonstrate that the loss of Tango2 in zebrafish results in growth defects, early lethality and increased susceptibility of skeletal muscle defects in response to extrinsic triggers, similar to TANGO2-deficient patients. Using lipidomics, we identified alterations in the glycerolipid pathway in tango2 mutants, which is critical for membrane stability and energy balance. Therefore, these studies provide insight into key disease processes in Tango2 deficiency and have increased our understanding of the impacts of specific defects on predisposition to environmental triggers in TANGO2-related disorders.
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Affiliation(s)
- Euri S. Kim
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - Jennifer G. Casey
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - Brian S. Tao
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - Arian Mansur
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - Nishanthi Mathiyalagan
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
| | - E. Diane Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Brandie M. Ehrmann
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Vandana A. Gupta
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital Harvard Medical School, Boston, MA 02115, USA
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Abraham EJ, Wallace ED, Kellogg JJ. A comparison of high- and low-resolution gas chromatography-mass spectrometry for herbal product classification: A case study with Ocimum essential oils. Phytochem Anal 2023; 34:680-691. [PMID: 37393908 DOI: 10.1002/pca.3258] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 04/17/2023] [Accepted: 06/12/2023] [Indexed: 07/04/2023]
Abstract
INTRODUCTION Selection of marker compounds for targeted chemical analysis is complicated when considering varying instrumentation and closely related plant species. High-resolution gas chromatography-mass spectrometry (GC-MS), via orbitrap detection, has yet to be evaluated for improved marker compound selection. OBJECTIVE This study directly compares high- and low-resolution GC-MS for botanical maker compound selection using Ocimum tenuiflorum L. (OT) and Ocimum gratissimum L. (OG) for botanical ingredient authentication. METHODS The essential oils of OT and OG were collected via hydrodistillation before untargeted chemical analysis with gas chromatography coupled to single-quadrupole (GC-SQ) and orbitrap (GC-Orbitrap) detectors. The Global Natural Products Social Molecular Networking (GNPS) software was used for compound annotation, and a manual search was used to find the 41 most common Ocimum essential oil metabolites. RESULTS The GC-Orbitrap resulted in 1.7-fold more metabolite detection and increased dynamic range compared to the GC-SQ. Spectral matching and manual searching were improved with GC-Orbitrap data. Each instrument had differing known compound concentrations; however, there was an overlap of six compounds with higher abundance in OG than OT and three compounds with a higher abundance in OT than OG, suggesting consistent detection of the most variable compounds. An unsupervised principal component analysis (PCA) could not discern the two species with either dataset. CONCLUSION GC-Orbitrap instrumentation improves compound detection, dynamic range, and feature annotation in essential oil analysis. However, considering both high- and low-resolution data may improve reliable marker compound selection, as GC-Orbitrap analysis alone did not improve unsupervised separation of two Ocimum species compared to GC-SQ data.
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Affiliation(s)
- Evelyn J Abraham
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - E Diane Wallace
- Mass Spectrometry Lab, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Joshua J Kellogg
- Intercollege Graduate Degree Program in Plant Biology, Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania, USA
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Sanders AE, Wallace ED, Ehrmann BM, Soma PS, Shaikh SR, Preisser JS, Ohrbach R, Fillingim RB, Slade GD. Non-esterified erythrocyte linoleic acid, arachidonic acid, and subjective sleep outcomes. Prostaglandins Leukot Essent Fatty Acids 2023; 195:102580. [PMID: 37451068 PMCID: PMC10529142 DOI: 10.1016/j.plefa.2023.102580] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 07/03/2023] [Accepted: 07/06/2023] [Indexed: 07/18/2023]
Abstract
OBJECTIVE This study investigated whether non-esterified erythrocyte omega-6 PUFAs were associated with subjective assessment of sleep quality and duration, and risk for obstructive sleep apnea. METHODS In this secondary analysis of the cross-sectional OPPERA-II study, 538 adults completed the Pittsburgh Sleep Quality Index (PSQI), reported their usual hours of sleep, and answered STOP screening questions for obstructive sleep apnea. Circulating non-esterified erythrocyte concentrations of omega-6 PUFA linoleic acid and arachidonic acid were quantified by liquid chromatography tandem mass spectroscopy. Sleep outcomes were dichotomized as poor (PSQI ≤5) vs good (PSQI ≥6) sleep quality, insufficient or excessive (≤6 or >9 h) vs good (7-9 h) sleep duration, and high (≥2 affirmative responses) vs low (<2 affirmative responses) risk for obstructive sleep apnea. Non-esterified omega-6 PUFAs and the continuous covariates of body mass index, Short Form (SF) 12 Health Survey Physical and Mental Component scores and resting measures of systolic and diastolic blood pressure were standardized for multivariable analysis. Categorical covariates were study site, age, sex, and race/ethnicity. Multivariable-adjusted logistic regression first estimated odds ratios (OR) and 95% confidence limits (CL) for sleep outcomes using linoleic acid as the main exposure. Analysis was then repeated using arachidonic acid as the main exposure. RESULTS In the multivariable-adjusted model, each standard deviation increase in non-esterified erythrocyte linoleic acid was associated with higher odds of poor sleep quality (OR=1.2, 95% CL: 1.1, 1.5), insufficient or excessive sleep (OR= 1.3, 95% CL: 1.1, 1.6) and high-risk for obstructive sleep apnea (OR=1.3, 95% CL: 1.1, 1.6). Likewise, for each standard deviation increase in non-esterified erythrocyte arachidonic acid, odds increased of poor sleep quality (OR=1.2, 95% CL: 1.1, 1.5), and insufficient or excessive sleep (OR=1.2, 95% CL: 1.1, 1.5). Odds of being high risk for obstructive sleep apnea increased with greater circulating arachidonic acid, but the association did not reach statistical significance (OR=1.1, 95% CL: 0.9, 1.4). CONCLUSION Non-esterified erythrocyte linoleic acid and arachidonic acid were associated with poor sleep quality and insufficient or excessive sleep duration. Linoleic acid, but not arachidonic acid, was also associated with high risk for obstructive sleep apnea.
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Affiliation(s)
- Anne E Sanders
- Division of Pediatric and Public Health, Adams School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - E Diane Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Brandie M Ehrmann
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Paul S Soma
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Saame R Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - John S Preisser
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Richard Ohrbach
- Department of Oral Diagnostic Sciences, University at Buffalo, Buffalo, NY 14260, USA
| | - Roger B Fillingim
- Department of Community Dentistry and Behavioral Science, University of Florida, Gainesville, FL 32611, USA; Pain Research and Intervention Center of Excellence, Department of Community Dentistry and Behavioral Science, College of Dentistry, University of Florida, Gainesville, FL 32611, USA
| | - Gary D Slade
- Division of Pediatric and Public Health, Adams School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Windham IA, Ragusa JV, Wallace ED, Wagner CH, White KK, Cohen S. APOE traffics to astrocyte lipid droplets and modulates triglyceride saturation and droplet size. bioRxiv 2023:2023.04.28.538740. [PMID: 37162939 PMCID: PMC10168303 DOI: 10.1101/2023.04.28.538740] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The E4 variant of APOE strongly predisposes individuals to late-onset Alzheimer's disease. We demonstrate that in response to neutral lipid synthesis, apolipoprotein E (APOE) in astrocytes can avoid translocation into the ER lumen and traffic to lipid droplets (LDs) via membrane bridges at ER-LD contacts. APOE knockdown promotes fewer, larger LDs containing more unsaturated triglyceride. This LD size distribution phenotype was rescued by chimeric APOE that targets only LDs. APOE4 - expressing astrocytes also form a small number of large LDs enriched in unsaturated triglyceride. Additionally, the larger LDs in APOE4 cells exhibit impaired turnover and increased sensitivity to lipid peroxidation. Our data indicate that APOE plays a previously unrecognized role as an LD surface protein that regulates LD size and composition. APOE4 is a toxic gain of function variant that causes aberrant LD composition and morphology. We propose that APOE4 astrocytes with large, unsaturated LDs are sensitized to lipid peroxidation or lipotoxicity, which could contribute to Alzheimer's disease risk. Summary Windham et al . discover that APOE in astrocytes can traffic to lipid droplets (LDs), where it modulates LD composition and size. Astrocytes expressing the Alzheimer's risk variant APOE4 form large LDs with impaired turnover and increased peroxidation sensitivity.
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Dunigan-Russell K, Yaeger MJ, Hodge MX, Kilburg-Basnyat B, Reece SW, Birukova A, Guttenberg MA, Novak C, Chung S, Ehrmann BM, Wallace ED, Tokarz D, Majumder N, Xia L, Christman JW, Shannahan J, Ballinger MN, Hussain S, Shaikh SR, Tighe RM, Gowdy KM. Scavenger receptor BI attenuates oxidized phospholipid-induced pulmonary inflammation. Toxicol Appl Pharmacol 2023; 462:116381. [PMID: 36681128 PMCID: PMC9983330 DOI: 10.1016/j.taap.2023.116381] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 12/30/2022] [Accepted: 01/11/2023] [Indexed: 01/20/2023]
Abstract
Damage associated molecular patterns (DAMPs) are molecules released from dead/dying cells following toxicant and/or environmental exposures that activate the immune response through binding of pattern recognition receptors (PRRs). Excessive production of DAMPs or failed clearance leads to chronic inflammation and delayed inflammation resolution. One category of DAMPs are oxidized phospholipids (oxPLs) produced upon exposure to high levels of oxidative stress, such as following ozone (O3) induced inflammation. OxPLs are bound by multiple classes of PRRs that include scavenger receptors (SRs) such as SR class B-1 (SR-BI) and toll-like receptors (TLRs). Interactions between oxPLs and PRRs appear to regulate inflammation; however, the role of SR-BI in oxPL-induced lung inflammation has not been defined. Therefore, we hypothesize that SR-BI is critical in protecting the lung from oxPL-induced pulmonary inflammation/injury. To test this hypothesis, C57BL/6J (WT) female mice were dosed with oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphatidylcholine (oxPAPC) by oropharyngeal aspiration which increased pulmonary SR-BI expression. Following oxPAPC exposure, SR-BI deficient (SR-BI-/-) mice exhibited increased lung pathology and inflammatory cytokine/chemokine production. Lipidomic analysis revealed that SR-BI-/- mice had an altered pulmonary lipidome prior to and following oxPAPC exposure, which correlated with increased oxidized phosphatidylcholines (PCs). Finally, we characterized TLR4-mediated activation of NF-κB following oxPAPC exposure and discovered that SR-BI-/- mice had increased TLR4 mRNA expression in lung tissue and macrophages, increased nuclear p65, and decreased cytoplasmic IκBα. Overall, we conclude that SR-BI is required for limiting oxPAPC-induced lung pathology by maintaining lipid homeostasis, reducing oxidized PCs, and attenuating TLR4-NF-κB activation, thereby preventing excessive and persistent inflammation.
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Affiliation(s)
- Katelyn Dunigan-Russell
- Pulmonary, Critical Care and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Michael J Yaeger
- Pulmonary, Critical Care and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Myles X Hodge
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC, United States
| | - Brita Kilburg-Basnyat
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC, United States
| | - Sky W Reece
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC, United States
| | - Anastasiya Birukova
- Department of Medicine, Duke University Medical Center, Durham, NC, United States
| | - Marissa A Guttenberg
- Department of Medicine, Duke University Medical Center, Durham, NC, United States
| | - Caymen Novak
- Pulmonary, Critical Care and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Sangwoon Chung
- Pulmonary, Critical Care and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Brandie Michelle Ehrmann
- Deparment of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - E Diane Wallace
- Deparment of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Debra Tokarz
- Experimental Pathology Laboratories, Inc., Research Triangle Park, NC, United States
| | - Nairrita Majumder
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, United States
| | - Li Xia
- College of Human and Health Sciences, Purdue University, West Lafayette, IN, United States
| | - John W Christman
- Pulmonary, Critical Care and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Jonathan Shannahan
- College of Human and Health Sciences, Purdue University, West Lafayette, IN, United States
| | - Megan N Ballinger
- Pulmonary, Critical Care and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Salik Hussain
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, United States
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Robert M Tighe
- Department of Medicine, Duke University Medical Center, Durham, NC, United States
| | - Kymberly M Gowdy
- Pulmonary, Critical Care and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.
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Virk R, Buddenbaum N, Al-Shaer A, Armstrong M, Manke J, Reisdorph N, Sergin S, Fenton JI, Wallace ED, Ehrmann BM, Lovins HB, Gowdy KM, Smith MR, Smith GJ, Kelada SN, Shaikh SR. Obesity reprograms the pulmonary polyunsaturated fatty acid-derived lipidome, transcriptome, and gene-oxylipin networks. J Lipid Res 2022; 63:100267. [PMID: 36028048 PMCID: PMC9508350 DOI: 10.1016/j.jlr.2022.100267] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 07/27/2022] [Accepted: 08/14/2022] [Indexed: 01/13/2023] Open
Abstract
Obesity exacerbates inflammation upon lung injury; however, the mechanisms by which obesity primes pulmonary dysregulation prior to external injury are not well studied. Herein, we tested the hypothesis that obesity dysregulates pulmonary PUFA metabolism that is central to inflammation initiation and resolution. We first show that a high-fat diet (HFD) administered to C57BL/6J mice increased the relative abundance of pulmonary PUFA-containing triglycerides and the concentration of PUFA-derived oxylipins (particularly prostaglandins and hydroxyeicosatetraenoic acids), independent of an increase in total pulmonary PUFAs, prior to onset of pulmonary inflammation. Experiments with a genetic model of obesity (ob/ob) generally recapitulated the effects of the HFD on the pulmonary oxylipin signature. Subsequent pulmonary next-generation RNA sequencing identified complex and unique transcriptional regulation with the HFD. We found the HFD increased pathways related to glycerophospholipid metabolism and immunity, including a unique elevation in B cell differentiation and signaling. Furthermore, we conducted computational integration of lipidomic with transcriptomic data. These analyses identified novel HFD-driven networks between glycerophospholipid metabolism and B cell receptor signaling with specific PUFA-derived pulmonary oxylipins. Finally, we confirmed the hypothesis by demonstrating that the concentration of pulmonary oxylipins, in addition to inflammatory markers, were generally increased in mice consuming a HFD upon ozone-induced acute lung injury. Collectively, these data show that a HFD dysregulates pulmonary PUFA metabolism prior to external lung injury, which may be a mechanism by which obesity primes the lungs to respond poorly to infectious and/or inflammatory challenges.
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Affiliation(s)
- Rafia Virk
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Nicole Buddenbaum
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Abrar Al-Shaer
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael Armstrong
- Department of Pharmaceutical Sciences, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, USA
| | - Jonathan Manke
- Department of Pharmaceutical Sciences, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, USA
| | - Nichole Reisdorph
- Department of Pharmaceutical Sciences, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, USA
| | - Selin Sergin
- Department of Food Science and Human Nutrition, College of Agriculture and Natural Resources and College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Jenifer I. Fenton
- Department of Food Science and Human Nutrition, College of Agriculture and Natural Resources and College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - E. Diane Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Brandie M. Ehrmann
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Hannah B. Lovins
- Division of Pulmonary, Critical Care and Sleep Medicine, The Ohio State University, Columbus, OH, USA
| | - Kymberly M. Gowdy
- Division of Pulmonary, Critical Care and Sleep Medicine, The Ohio State University, Columbus, OH, USA
| | - M Ryan Smith
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA, USA,Atlanta Department of Veterans Affairs Medical Center, Decatur, GA, USA
| | - Gregory J. Smith
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Samir N.P. Kelada
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,For correspondence: Saame Raza Shaikh
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10
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Schoenborn AA, Yannarell SM, Wallace ED, Clapper H, Weinstein IC, Shank EA. Defining the Expression, Production, and Signaling Roles of Specialized Metabolites during Bacillus subtilis Differentiation. J Bacteriol 2021; 203:e0033721. [PMID: 34460312 PMCID: PMC8544424 DOI: 10.1128/jb.00337-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/11/2021] [Indexed: 11/20/2022] Open
Abstract
Bacterial specialized (or secondary) metabolites are structurally diverse molecules that mediate intra- and interspecies interactions by altering growth and cellular physiology and differentiation. Bacillus subtilis, a Gram-positive model bacterium commonly used to study biofilm formation and sporulation, has the capacity to produce more than 10 specialized metabolites. Some of these B. subtilis specialized metabolites have been investigated for their role in facilitating cellular differentiation, but only rarely has the behavior of multiple metabolites been simultaneously investigated. In this study, we explored the interconnectivity of differentiation (biofilm and sporulation) and specialized metabolites in B. subtilis. Specifically, we interrogated how development influences specialized metabolites and vice versa. Using the sporulation-inducing medium DSM, we found that the majority of the specialized metabolites examined are expressed and produced during biofilm formation and sporulation. Additionally, we found that six of these metabolites (surfactin, ComX, bacillibactin, bacilysin, subtilosin A, and plipastatin) are necessary signaling molecules for proper progression of B. subtilis differentiation. This study further supports the growing body of work demonstrating that specialized metabolites have essential physiological functions as cell-cell communication signals in bacteria. IMPORTANCE Bacterially produced specialized metabolites are frequently studied for their potential use as antibiotics and antifungals. However, a growing body of work has suggested that the antagonistic potential of specialized metabolites is not their only function. Here, using Bacillus subtilis as our model bacterium, we demonstrated that developmental processes such as biofilm formation and sporulation are tightly linked to specialized metabolite gene expression and production. Additionally, under our differentiation-inducing conditions, six out of the nine specialized metabolites investigated behave as intraspecific signals that impact B. subtilis physiology and influence biofilm formation and sporulation. Our work supports the viewpoint that specialized metabolites have a clear role as cell-cell signaling molecules within differentiated populations of bacteria.
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Affiliation(s)
- Alexi A. Schoenborn
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Sarah M. Yannarell
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - E. Diane Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Haley Clapper
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Ilon C. Weinstein
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Elizabeth A. Shank
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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11
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Todd DA, Kellogg JJ, Wallace ED, Khin M, Flores-Bocanegra L, Tanna RS, McIntosh S, Raja HA, Graf TN, Hemby SE, Paine MF, Oberlies NH, Cech NB. Chemical composition and biological effects of kratom (Mitragyna speciosa): In vitro studies with implications for efficacy and drug interactions. Sci Rep 2020; 10:19158. [PMID: 33154449 PMCID: PMC7645423 DOI: 10.1038/s41598-020-76119-w] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/22/2020] [Indexed: 01/24/2023] Open
Abstract
The safety and efficacy of kratom (Mitragyna speciosa) for treatment of pain is highly controversial. Kratom produces more than 40 structurally related alkaloids, but most studies have focused on just two of these, mitragynine and 7-hydroxymitragynine. Here, we profiled 53 commercial kratom products using untargeted LC-MS metabolomics, revealing two distinct chemotypes that contain different levels of the alkaloid speciofoline. Both chemotypes were confirmed with DNA barcoding to be M. speciosa. To evaluate the biological relevance of variable speciofoline levels in kratom, we compared the opioid receptor binding activity of speciofoline, mitragynine, and 7-hydroxymitragynine. Mitragynine and 7-hydroxymitragynine function as partial agonists of the human µ-opioid receptor, while speciofoline does not exhibit measurable binding affinity at the µ-, δ- or ƙ-opioid receptors. Importantly, mitragynine and 7-hydroxymitragynine demonstrate functional selectivity for G-protein signaling, with no measurable recruitment of β-arrestin. Overall, the study demonstrates the unique binding and functional profiles of the kratom alkaloids, suggesting potential utility for managing pain, but further studies are needed to follow up on these in vitro findings. All three kratom alkaloids tested inhibited select cytochrome P450 enzymes, suggesting a potential risk for adverse interactions when kratom is co-consumed with drugs metabolized by these enzymes.
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Affiliation(s)
- D A Todd
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA
| | - J J Kellogg
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - E D Wallace
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA
- Department of Chemistry, The University of North Carolina Chapel Hill, Chapel Hill, NC, 27599, USA
| | - M Khin
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA
| | - L Flores-Bocanegra
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA
| | - R S Tanna
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA
| | - S McIntosh
- Department of Basic Pharmaceutical Sciences, High Point University, High Point, NC, 27268, USA
| | - H A Raja
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA
| | - T N Graf
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA
| | - S E Hemby
- Department of Basic Pharmaceutical Sciences, High Point University, High Point, NC, 27268, USA
| | - M F Paine
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA
| | - N H Oberlies
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA
| | - N B Cech
- Department of Chemistry and Biochemistry, The University of North Carolina Greensboro, 435 Sullivan Bldg., 301 McIver St., Greensboro, NC, 27402, USA.
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12
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Flores-Bocanegra L, Raja HA, Graf TN, Augustinović M, Wallace ED, Hematian S, Kellogg JJ, Todd DA, Cech NB, Oberlies NH. The Chemistry of Kratom [ Mitragyna speciosa]: Updated Characterization Data and Methods to Elucidate Indole and Oxindole Alkaloids. J Nat Prod 2020; 83:2165-2177. [PMID: 32597657 PMCID: PMC7718854 DOI: 10.1021/acs.jnatprod.0c00257] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Two separate commercial products of kratom [Mitragyna speciosa (Korth.) Havil. Rubiaceae] were used to generate reference standards of its indole and oxindole alkaloids. While kratom has been studied for over a century, the characterization data in the literature for many of the alkaloids are either incomplete or inconsistent with modern standards. As such, full 1H and 13C NMR spectra, along with HRESIMS and ECD data, are reported for alkaloids 1-19. Of these, four new alkaloids (7, 11, 17, and 18) were characterized using 2D NMR data, and the absolute configurations of 7, 17, and 18 were established by comparison of experimental and calculated ECD spectra. The absolute configuration for the N(4)-oxide (11) was established by comparison of NMR and ECD spectra of its reduced product with those for compound 7. In total, 19 alkaloids were characterized, including the indole alkaloid mitragynine (1) and its diastereoisomers speciociliatine (2), speciogynine (3), and mitraciliatine (4); the indole alkaloid paynantheine (5) and its diastereoisomers isopaynantheine (6) and epiallo-isopaynantheine (7); the N(4)-oxides mitragynine-N(4)-oxide (8), speciociliatine-N(4)-oxide (9), isopaynantheine-N(4)-oxide (10), and epiallo-isopaynantheine-N(4)-oxide (11); the 9-hydroxylated oxindole alkaloids speciofoline (12), isorotundifoleine (13), and isospeciofoleine (14); and the 9-unsubstituted oxindoles corynoxine A (15), corynoxine B (16), 3-epirhynchophylline (17), 3-epicorynoxine B (18), and corynoxeine (19). With the ability to analyze the spectroscopic data of all of these compounds concomitantly, a decision tree was developed to differentiate these kratom alkaloids based on a few key chemical shifts in the 1H and/or 13C NMR spectra.
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Affiliation(s)
- Laura Flores-Bocanegra
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Huzefa A Raja
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Tyler N Graf
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Mario Augustinović
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - E Diane Wallace
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Shabnam Hematian
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Joshua J Kellogg
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Daniel A Todd
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Nadja B Cech
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Nicholas H Oberlies
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
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13
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Wallace ED, Todd DA, Harnly JM, Cech NB, Kellogg JJ. Identification of adulteration in botanical samples with untargeted metabolomics. Anal Bioanal Chem 2020; 412:4273-4286. [PMID: 32347364 DOI: 10.1007/s00216-020-02678-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 03/27/2020] [Accepted: 04/21/2020] [Indexed: 01/28/2023]
Abstract
Adulteration remains an issue in the dietary supplement industry, including botanical supplements. While it is common to employ a targeted analysis to detect known adulterants, this is difficult when little is known about the sample set. With this study, untargeted metabolomics using liquid chromatography coupled to ultraviolet-visible spectroscopy (LC-UV) or high-resolution mass spectrometry (LC-MS) was employed to detect adulteration in botanical dietary supplements. A training set was prepared by combining Hydrastis canadensis L. with a known adulterant, Coptis chinensis Franch., in ratios ranging from 5 to 95% adulteration. The metabolomics datasets were analyzed using both unsupervised (principal component analysis and composite score) and supervised (SIMCA) techniques. Palmatine, a known H. canadensis metabolite, was quantified as a targeted analysis comparison. While the targeted analysis was the most sensitive method tested in detecting adulteration, statistical analyses of the untargeted metabolomics datasets detected adulteration of the goldenseal samples, with SIMCA providing the greatest discriminating potential. Graphical abstract.
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Affiliation(s)
- E Diane Wallace
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC, 27402, USA
| | - Daniel A Todd
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC, 27402, USA
| | - James M Harnly
- U.S. Department of Agriculture, Agricultural Research Service, Food Composition and Methods Development Laboratory, Beltsville Human Nutrition Research Center, Beltsville, MD, 20705, USA
| | - Nadja B Cech
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC, 27402, USA
| | - Joshua J Kellogg
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC, 27402, USA.
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA, 16802, USA.
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14
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Abstract
In pregnant rock hyraxes isolated leucocytes metabolise both [3H]pregnenolone and [3H]progesterone while whole blood, erythrocytes and an erythrocyte/leucocyte mixture only metabolised [3H]progesterone. Plasma displayed no tendency to metabolically convert any one of these two steroids. In whole blood [3H]progesterone appears to be converted to 5alpha-pregnane-3,20-dione and a compound with chromatographic properties similar to that of 5alpha-pregnan-3alpha-ol-20-one. 5Alpha-pregnane-3,20-dione exhibited a high relative binding affinity for the uterine progesterone eceptor (94%), but 5alpha-pregnan-3alpha-ol-20-one displayed very little affinity for the same receptor (0.4%). 5Alpha-pregnane-3,20-dione may therefore aid in the maintenance of pregnancy. Corpora lutea metabolised progesterone to 17alpha-hydroxyprogesterone, a compound exhibiting no progestational function because of its low relative binding affinity for the uterine progesterone receptor (2%). Progesterone appears to be the main product of the corpus luteum. However, 5alpha-pregnane-3,20-dione circulated at concentrations approximately 8.5 times higher than progesterone, probably due to the metabolic conversion of progesterone to 5alpha-pregnane-3,20-dione by the blood. We conclude that in the hyrax progesterone, produced by the corpora lutea, enters the circulation, where it is reduced to 5alpha-pregnanes. 5Alpha-pregane-3,20-dione may then be transported to the uterus where it binds to the progesterone receptor to assist in the maintenance of pregnancy. This mechanism appears to be analogous to that of the African elephant which is phylogenetically related to the hyrax, except that in the elephant the 5alpha-reduced metabolites are produced by luteal tissue and not the blood.
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Affiliation(s)
- S Kirkman
- Department of Zoology & Entomology, University of Pretoria, South Africa
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