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Indika NLR, Senarathne UD, Malvaso A, Darshana D, Owens SC, Mansouri B, Semenova Y, Bjørklund G. Abnormal Porphyrin Metabolism in Autism Spectrum Disorder and Therapeutic Implications. Mol Neurobiol 2024; 61:3851-3866. [PMID: 38032468 DOI: 10.1007/s12035-023-03722-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023]
Abstract
Autism spectrum disorder (ASD) is a mosaic of neurodevelopmental conditions composed of early-onset social interaction and communication deficits, along with repetitive and/or restricted patterns of activities, behavior, and interests. ASD affects around 1% of children worldwide, with a male predominance. Energy, porphyrin, and neurotransmitter homeostasis are the key metabolic pathways affected by heavy metal exposure, potentially implicated in the pathogenesis of ASD. Exposure to heavy metals can lead to an altered porphyrin metabolism due to enzyme inhibition by heavy metals. Heavy metal exposure, inborn genetic susceptibility, and abnormal thiol and selenol metabolism may play a significant role in the urinary porphyrin profile anomalies observed in ASD. Altered porphyrin metabolism in ASD may also be associated with, vitamin B6 deficiency, hyperoxalemia, hyperhomocysteinemia, and hypomagnesemia. The present review considers the abnormal porphyrin metabolism in ASD in relation to the potential pathogenic mechanism and discusses the possible metabolic therapies such as vitamins, minerals, cofactors, and antioxidants that need to be explored in future research. Such targeted therapeutic therapies would bring about favorable outcomes such as improvements in core and co-occurring symptoms.
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Affiliation(s)
- Neluwa-Liyanage R Indika
- Department of Biochemistry, Faculty of Medical Sciences, University of Sri Jayewardenepura, Nugegoda, 10250, Sri Lanka.
| | - Udara D Senarathne
- Department of Biochemistry, Faculty of Medical Sciences, University of Sri Jayewardenepura, Nugegoda, 10250, Sri Lanka
- Department of Chemical Pathology, Monash Health Pathology, Monash Health, Clayton, Victoria, Australia
| | - Antonio Malvaso
- IRCCS "C. Mondino" Foundation, National Neurological Institute, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Dhanushka Darshana
- Department of Pharmacy, Faculty of Allied Health Sciences, University of Ruhuna, Galle, Sri Lanka
| | - Susan C Owens
- Autism Oxalate Project, Autism Research Institute, San Diego, CA, USA
| | - Borhan Mansouri
- Substance Abuse Prevention Research Center, Research Institute for Health, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Yuliya Semenova
- Nazarbayev University School of Medicine, Astana, Kazakhstan
| | - Geir Bjørklund
- Council for Nutritional and Environmental Medicine, Toften 24, 8610, Mo i Rana, Norway.
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Balwani M, Keel S, Meissner P, Sonderup M, Stein P, Yasuda M. Case-based discussion of the acute hepatic porphyrias: Updates on pathogenesis, diagnosis and management. Liver Int 2024. [PMID: 38618923 DOI: 10.1111/liv.15924] [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: 01/14/2024] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/16/2024]
Abstract
The acute hepatic porphyrias (AHPs) include three autosomal dominant disorders, acute intermittent porphyria, variegate porphyria and hereditary coproporphyria, and the ultra-rare autosomal recessive 5-aminolevulinic acid dehydratase-deficient porphyria. All four are characterized by episodic acute neurovisceral attacks that can be life-threatening if left untreated. The attacks are precipitated by factors that induce hepatic 5-aminolevulinic acid synthase 1 (ALAS1), resulting in accumulation of the porphyrin precursors, 5-aminolevulinic acid and porphobilinogen, which are believed to cause neurotoxicity. Diagnosis of these rare disorders is often delayed because the symptoms are non-specific with many common aetiologies. However, once clinical suspicion of an AHP is raised, diagnosis can be made by specialized biochemical testing, particularly during attacks. Moderate or severe attacks are treated with intravenous hemin infusions, together with supportive care to relieve pain and other symptoms. Prophylactic treatments are recommended in patients with confirmed recurrent attacks (≥4 attacks in a maximum period of 12 months), the most effective being givosiran, an RNAi therapeutic targeting hepatocyte ALAS1 mRNA. AHP patients with clinically and/or biochemically active disease are at elevated risk for developing long-term complications, including chronic kidney disease, chronic hypertension and hepatocellular carcinoma, thus, surveillance is recommended. Here, using a case-based format, we provide an update on the pathogenesis, diagnosis and treatment of the AHPs based on literature review and clinical experiences.
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Affiliation(s)
- Manisha Balwani
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Siobán Keel
- Department of Medicine, Division of Hematology and Oncology, University of Washington, Seattle, Washington, USA
| | - Peter Meissner
- Department of Integrative Biomedical Sciences, Division of Medical Biochemistry and Structural Biology, University of Cape Town, Cape Town, South Africa
| | - Mark Sonderup
- Division of Hepatology, Department of Medicine, Faculty of Health Sciences, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa
| | - Penelope Stein
- Department of Haematological Medicine, King's College Hospital, London, UK
| | - Makiko Yasuda
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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Yasuda M. [Acute hepatic porphyrias: pathophysiology and pathogenesis of acute attacks]. Rinsho Shinkeigaku 2024; 64:8-16. [PMID: 38092415 DOI: 10.5692/clinicalneurol.cn-001856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
Heme is an iron-containing molecule essential for virtually all living organisms. However, excessive heme is cytotoxic, necessitating tight regulation of intracellular heme concentration. The acute hepatic porphyrias (AHPs) are a group of rare inborn errors of heme biosynthesis that are characterized by episodic acute neurovisceral attacks that are precipitated by various factors. The AHPs are often misdiagnosed, as the acute attack symptom are non-specific and can be attributed to other more common causes. Understanding how heme biosynthesis is dysregulated in AHP patients and the mechanism by which acute attacks are precipitated will aid in accurate and rapid diagnoses, and subsequently, appropriate treatment of these disorders. Therefore, this review article will focus on the biochemical and molecular changes that occur during an acute attack and present what is currently known regarding the underlying pathogenesis of acute attacks.
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Affiliation(s)
- Makiko Yasuda
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai
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Yasuda M, Keel S, Balwani M. RNA interference therapy in acute hepatic porphyrias. Blood 2023; 142:1589-1599. [PMID: 37027823 PMCID: PMC10656724 DOI: 10.1182/blood.2022018662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/27/2023] [Accepted: 03/25/2023] [Indexed: 04/09/2023] Open
Abstract
The acute hepatic porphyrias (AHPs) are inherited disorders of heme biosynthesis characterized by life-threatening acute neurovisceral attacks precipitated by factors that upregulate hepatic 5-aminolevulinic acid synthase 1 (ALAS1) activity. Induction of hepatic ALAS1 leads to the accumulation of porphyrin precursors, in particular 5-aminolevulinic acid (ALA), which is thought to be the neurotoxic mediator leading to acute attack symptoms such as severe abdominal pain and autonomic dysfunction. Patients may also develop debilitating chronic symptoms and long-term medical complications, including kidney disease and an increased risk of hepatocellular carcinoma. Exogenous heme is the historical treatment for attacks and exerts its therapeutic effect by inhibiting hepatic ALAS1 activity. The pathophysiology of acute attacks provided the rationale to develop an RNA interference therapeutic that suppresses hepatic ALAS1 expression. Givosiran is a subcutaneously administered N-acetylgalactosamine-conjugated small interfering RNA against ALAS1 that is taken up nearly exclusively by hepatocytes via the asialoglycoprotein receptor. Clinical trials established that the continuous suppression of hepatic ALAS1 mRNA via monthly givosiran administration effectively reduced urinary ALA and porphobilinogen levels and acute attack rates and improved quality of life. Common side effects include injection site reactions and increases in liver enzymes and creatinine. Givosiran was approved by the US Food and Drug Administration and European Medicines Agency in 2019 and 2020, respectively, for the treatment of patients with AHP. Although givosiran has the potential to decrease the risk of chronic complications, long-term data on the safety and effects of sustained ALAS1 suppression in patients with AHP are lacking.
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Affiliation(s)
- Makiko Yasuda
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Siobán Keel
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA
| | - Manisha Balwani
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
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Kazamel M, Pischik E, Desnick RJ. Pain in acute hepatic porphyrias: Updates on pathophysiology and management. Front Neurol 2022; 13:1004125. [PMID: 36479055 PMCID: PMC9719963 DOI: 10.3389/fneur.2022.1004125] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/07/2022] [Indexed: 11/22/2022] Open
Abstract
Acute hepatic porphyrias (AHPs) typically present with recurrent acute attacks of severe abdominal pain and acute autonomic dysfunction. While chronic symptoms were historically overlooked in the literature, recent studies have reported increased prevalence of chronic, mainly neuropathic, pain between the attacks. Here we characterize acute and chronic pain as prominent manifestations of the AHPs and discuss their pathophysiology and updated management. In addition to the severe abdominal pain, patients could experience low back pain, limb pain, and headache during acute attacks. Chronic pain between the attacks is typically neuropathic and reported mainly by patients who undergo recurrent attacks. While the acute abdominal pain during attacks is likely mediated by autonomic neuropathy, chronic pain likely represents delayed recovery of the acute neuropathy with ongoing small fiber neuropathy in addition to peripheral and/or central sensitization. δ-aminolaevulinic acid (ALA) plays a major role in acute and chronic pain via its neurotoxic effect, especially where the blood-nerve barrier is less restrictive or absent i.e., the autonomic ganglia, nerve roots, and free nerve endings. For earlier diagnosis, we recommend testing a spot urine porphobilinogen (PBG) analysis in any patient with recurrent severe acute abdominal pain with no obvious explanation, especially if associated with neuropathic pain, hyponatremia, autonomic dysfunction, or encephalopathy. Of note, it is mandatory to exclude AHPs in any acute painful neuropathy. Between the attacks, diagnostic testing for AHPs should be considered for patients with a past medical history of acute/subacute neuropathy, frequent emergency room visits with abdominal pain, and behavioral changes. Pain during the attacks should be treated with opiates combined with hemin infusions. Symptomatic treatment of chronic pain should start with gabapentinoids and certain antidepressants before opiates. Givosiran reduces levels of ALA and PBG and likely has long-term benefits for chronic pain, especially if started early during the course of the disease.
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Affiliation(s)
- Mohamed Kazamel
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, United States
- *Correspondence: Mohamed Kazamel
| | - Elena Pischik
- Department of Neurology, Consultative and Diagnostic Center With Polyclinics, St. Petersburg, Russia
| | - Robert J. Desnick
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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Ricci A, Di Pierro E, Marcacci M, Ventura P. Mechanisms of Neuronal Damage in Acute Hepatic Porphyrias. Diagnostics (Basel) 2021; 11:diagnostics11122205. [PMID: 34943446 PMCID: PMC8700611 DOI: 10.3390/diagnostics11122205] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 01/12/2023] Open
Abstract
Porphyrias are a group of congenital and acquired diseases caused by an enzymatic impairment in the biosynthesis of heme. Depending on the specific enzyme involved, different types of porphyrias (i.e., chronic vs. acute, cutaneous vs. neurovisceral, hepatic vs. erythropoietic) are described, with different clinical presentations. Acute hepatic porphyrias (AHPs) are characterized by life-threatening acute neuro-visceral crises (acute porphyric attacks, APAs), featuring a wide range of neuropathic (central, peripheral, autonomic) manifestations. APAs are usually unleashed by external "porphyrinogenic" triggers, which are thought to cause an increased metabolic demand for heme. During APAs, the heme precursors δ-aminolevulinic acid (ALA) and porphobilinogen (PBG) accumulate in the bloodstream and urine. Even though several hypotheses have been developed to explain the protean clinical picture of APAs, the exact mechanism of neuronal damage in AHPs is still a matter of debate. In recent decades, a role has been proposed for oxidative damage caused by ALA, mitochondrial and synaptic ALA toxicity, dysfunction induced by relative heme deficiency on cytochromes and other hemeproteins (i.e., nitric oxide synthases), pyridoxal phosphate functional deficiency, derangements in the metabolic pathways of tryptophan, and other factors. Since the pathway leading to the biosynthesis of heme is inscribed into a complex network of interactions, which also includes some fundamental processes of basal metabolism, a disruption in any of the steps of this pathway is likely to have multiple pathogenic effects. Here, we aim to provide a comprehensive review of the current evidence regarding the mechanisms of neuronal damage in AHPs.
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Affiliation(s)
- Andrea Ricci
- Internal Medicine Unit, Department of Medical and Surgical Science for Children and Adults, University of Modena e Reggio Emilia, 41124 Modena, Italy; (A.R.); (M.M.)
| | - Elena Di Pierro
- Dipartimento di Medicina Interna, Fondazione IRCSS Cà Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy;
| | - Matteo Marcacci
- Internal Medicine Unit, Department of Medical and Surgical Science for Children and Adults, University of Modena e Reggio Emilia, 41124 Modena, Italy; (A.R.); (M.M.)
| | - Paolo Ventura
- Internal Medicine Unit, Department of Medical and Surgical Science for Children and Adults, University of Modena e Reggio Emilia, 41124 Modena, Italy; (A.R.); (M.M.)
- Correspondence: ; Tel.: +39-059-4225-542
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Lopes de Andrade V, Serrazina D, Mateus ML, Batoréu C, Aschner M, Marreilha Dos Santos AP. Multibiomarker approach to assess the magnitude of occupational exposure and effects induced by a mixture of metals. Toxicol Appl Pharmacol 2021; 429:115684. [PMID: 34437931 PMCID: PMC8449837 DOI: 10.1016/j.taap.2021.115684] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/13/2021] [Accepted: 08/14/2021] [Indexed: 01/23/2023]
Abstract
Metals and metalloids including lead (Pb), arsenic (As) and manganese (Mn) can occur as mixtures in occupational contexts, such as mines. These chemicals are all known to be neurotoxic and provoke changes in heme metabolism also known to induce neurotoxicity. The objective of this work was to propose a multi-biomarker (BM) methodology to screen subjects exposed to the mixture of Pb, As and Mn and assess the severity of their exposure/effects, in an individual basis. The urinary levels of the metals, dela-aminolevulinic acid (ALA) and porphyrins were determined in Portuguese miners and in a control group. The combination of Pb and As urinary levels had the highest capability to identify subjects occupationally exposed to this mixture in mines, as evaluated through Receiver Operating Characteristic (ROC) (A = 98.2%; p < 0.05), allowing that 94.2% of 86 studied subjects were properly identified and the generation of an equation indicating the odd of a subject be considered as exposed to the metal mixture. The combination of urinary ALA and porphyrins revealed to be best one to be applied in the assessment of subjects with high, intermediate, and low magnitudes of exposure/effects, with 95.7% of 46 miners classified correctly according to their severity sub-group and allowing to generate equations, which can be applied in new subjects. The proposed methodology showed a satisfactory performance, evaluating in an integrated manner the magnitude of exposure/effects of the exposed workers, may contributing to improve the control of their health.
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Affiliation(s)
- V Lopes de Andrade
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
| | - D Serrazina
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - M L Mateus
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - C Batoréu
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - M Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Forchheimer 209, 1300 Morris Park Avenue, Bronx, NY 10461, United States of America
| | - A P Marreilha Dos Santos
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
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Porphyric Neuropathy: Pathophysiology, Diagnosis, and Updated Management. Curr Neurol Neurosci Rep 2020; 20:56. [PMID: 33026560 DOI: 10.1007/s11910-020-01078-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2020] [Indexed: 12/20/2022]
Abstract
PURPOSE OF REVIEW To review the peripheral neurological complications of the acute hepatic porphyrias, as well as the latest advances in their pathophysiology and management. RECENT FINDINGS The diagnosis of porphyric neuropathy remains challenging as varying neuropathic patterns are encountered depending on disease stage, including a non-length-dependent distribution pattern. The major pathophysiologic mechanism is δ-aminolevulinic acid (ALA)-induced neurotoxicity. The less restrictive blood-nerve barrier in the autonomic ganglia and myenteric plexus may explain the frequency of dysautonomic manifestations. Recently, a prophylactic small interfering RNA (siRNA)-based therapy that reduces hepatic ALA Synthase-1 mRNA was approved for patients with recurrent neuro-visceral attacks. Neurologists should appreciate the varying patterns of porphyric neuropathy. As with most toxin-induced axonopathies, long-term outcomes depend on early diagnosis and treatment. While the short-term clinical and biochemical benefits of siRNA-based therapy are known, its long-term effects on motor recovery, chronic pain, and dysautonomic manifestations are yet to be determined.
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Yasuda M, Gan L, Chen B, Yu C, Zhang J, Gama-Sosa MA, Pollak DD, Berger S, Phillips JD, Edelmann W, Desnick RJ. Homozygous hydroxymethylbilane synthase knock-in mice provide pathogenic insights into the severe neurological impairments present in human homozygous dominant acute intermittent porphyria. Hum Mol Genet 2020; 28:1755-1767. [PMID: 30615115 DOI: 10.1093/hmg/ddz003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 12/07/2018] [Accepted: 12/31/2018] [Indexed: 12/13/2022] Open
Abstract
Acute intermittent porphyria (AIP) is an inborn error of heme biosynthesis due to the deficiency of hydroxymethylbilane synthase (HMBS) activity. Human AIP heterozygotes have episodic acute neurovisceral attacks that typically start after puberty, whereas patients with homozygous dominant AIP (HD-AIP) have early-onset chronic neurological impairment, including ataxia and psychomotor retardation. To investigate the dramatically different manifestations, knock-in mice with human HD-AIP missense mutations c.500G>A (p.Arg167Glu) or c.518_519GC>AG (p.Arg173Glu), designated R167Q or R173Q mice, respectively, were generated and compared with the previously established T1/T2 mice with ~30% residual HMBS activity and the heterozygous AIP phenotype. Homozygous R173Q mice were embryonic lethal, while R167Q homozygous mice (R167Q+/+) had ~5% of normal HMBS activity, constitutively elevated plasma and urinary 5-aminolevulinic acid (ALA) and porphobilinogen (PBG), profound early-onset ataxia, delayed motor development and markedly impaired rotarod performance. Central nervous system (CNS) histology was grossly intact, but CNS myelination was delayed and overall myelin volume was decreased. Heme concentrations in liver and brain were similar to those of T1/T2 mice. Notably, ALA and PBG concentrations in the cerebral spinal fluid and CNS regions were markedly elevated in R167Q+/+ mice compared with T1/T2 mice. When the T1/T2 mice were administered phenobarbital, ALA and PBG markedly accumulated in their liver and plasma, but not in the CNS, indicating that ALA and PBG do not readily cross the blood-brain barrier. Taken together, these studies suggest that the severe HD-AIP neurological phenotype results from decreased myelination and the accumulation of locally produced neurotoxic porphyrin precursors within the CNS.
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Affiliation(s)
- Makiko Yasuda
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Lin Gan
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Brenden Chen
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Chunli Yu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jinglan Zhang
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Miguel A Gama-Sosa
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,General Medical Research Service, James J. Peters Department of Veterans Affairs Medical Center, Bronx, NY, USA
| | - Daniela D Pollak
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Stefanie Berger
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - John D Phillips
- Division of Hematology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | | | - Robert J Desnick
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Pulgar VM, Yasuda M, Gan L, Desnick RJ, Bonkovsky HL. Sex differences in vascular reactivity in mesenteric arteries from a mouse model of acute intermittent porphyria. Mol Genet Metab 2019; 128:376-381. [PMID: 30639047 PMCID: PMC6612470 DOI: 10.1016/j.ymgme.2019.01.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/08/2018] [Accepted: 01/05/2019] [Indexed: 12/24/2022]
Abstract
BACKGROUND AND AIMS Acute intermittent porphyria (AIP) results from a partial deficiency of porphobilinogen deaminase (PBGD). Symptomatic AIP patients, most of whom are women, experience acute attacks characterized by severe abdominal pain and abrupt increases in blood pressure. Here, we characterized the reactivity of mesenteric arteries from male and female AIP mice with ~30% of normal PBGD activity and wild type C57BL/6 mice. METHODS An acute porphyric attack was induced in AIP mice by treatment with phenobarbital. Vascular responses to K+, phenylephrine (PE), acetylcholine (ACh), and hemin were determined (Wire Multi Myograph). RESULTS Maximal contraction to PE was increased in arteries from male and female AIP mice (p < .05) during an induced attack of acute porphyria. Female AIP arteries had increased sensitivity to PE (p < .05) even after nitric oxide (NO) blockade with Nω-nitro-L-arginine methyl ester (L-NAME) (p < .05). Maximal relaxation to ACh was similar in males and females with lower sensitivity in female AIP arteries (p < .05). Hemin induced greater relaxation in AIP arteries in both males and females (p < .05). SUMMARY/CONCLUSIONS Sex differences in this AIP mouse model include a pro-contractile response in females. These alterations may contribute to the increased blood pressure during an acute attack and provide a novel mechanism of action whereby heme ameliorates the attacks.
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Affiliation(s)
- Victor M Pulgar
- Department of Pharmaceutical Sciences, Campbell University, Buies Creek, NC, USA; Department of Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
| | - Makiko Yasuda
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, NY, USA.
| | - Lin Gan
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, NY, USA.
| | - Robert J Desnick
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, NY, USA.
| | - Herbert L Bonkovsky
- Section on Gastroenterology & Hepatology, Wake Forest University/NC Baptist Medical Center, Winston-Salem, NC, USA.
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Yasuda M, Desnick RJ. Murine models of the human porphyrias: Contributions toward understanding disease pathogenesis and the development of new therapies. Mol Genet Metab 2019; 128:332-341. [PMID: 30737139 PMCID: PMC6639143 DOI: 10.1016/j.ymgme.2019.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 01/11/2019] [Accepted: 01/12/2019] [Indexed: 02/07/2023]
Abstract
Mouse models of the human porphyrias have proven useful for investigations of disease pathogenesis and to facilitate the development of new therapeutic approaches. To date, mouse models have been generated for all major porphyrias, with the exception of X-linked protoporphyria (XLP) and the ultra rare 5-aminolevulinic acid dehydratase deficient porphyria (ADP). Mouse models have been generated for the three autosomal dominant acute hepatic porphyrias, acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), and variegate porphyria (VP). The AIP mice, in particular, provide a useful investigative model as they have been shown to have acute biochemical attacks when induced with the prototypic porphyrinogenic drug, phenobarbital. In addition to providing important insights into the disease pathogenesis of the neurological impairment in AIP, these mice have been valuable for preclinical evaluation of liver-targeted gene therapy and RNAi-mediated approaches. Mice with severe HMBS deficiency, which clinically and biochemically mimic the early-onset homozygous dominant AIP (HD-AIP) patients, have been generated and were used to elucidate the striking phenotypic differences between AIP and HD-AIP. Mice modeling the hepatocutaneous porphyria, porphyria cutanea tarda (PCT), made possible the identification of the iron-dependent inhibitory mechanism of uroporphyrinogen decarboxylase (UROD) that leads to symptomatic PCT. Mouse models for the two autosomal recessive erythropoietic porphyrias, congenital erythropoietic porphyria (CEP) and erythropoeitic protoporphyria (EPP), recapitulate many of the clinical and biochemical features of the severe human diseases and have been particularly useful for evaluation of bone marrow transplantation and hematopoietic stem cell (HSC)-based gene therapy approaches. The EPP mice have also provided valuable insights into the underlying pathogenesis of EPP-induced liver damage and anemia.
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Affiliation(s)
- Makiko Yasuda
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Robert J Desnick
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Hillgartner MA, Coker SB, Koenig AE, Moore ME, Barnby E, MacGregor GG. Tyrosinemia type I and not treatment with NTBC causes slower learning and altered behavior in mice. J Inherit Metab Dis 2016; 39:673-682. [PMID: 27271696 DOI: 10.1007/s10545-016-9949-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 12/12/2022]
Abstract
Tyrosinemia type I is a recessive inborn error of metabolism caused by mutations in the fumarylacetoacetate hydrolase (FAH) gene, coding for the final enzyme in the metabolism of tyrosine. This renders FAH nonfunctional and without treatment, toxic metabolites accumulate causing liver and kidney damage. Introduction of the drug NTBC in 2002 offered a treatment which inhibits an upstream enzyme, preventing the production of the toxic metabolites. There is now a long-term survival rate of greater than 90 % in children, but there are reports of lower cognitive function and IQ as well as schooling and behavioral problems in these children. We studied a mouse model of tyrosinemia type I to gain insight into the effects of tyrosinemia type I and treatment with NTBC on mouse learning, memory, and behavior. In the Barnes maze, visual and spatial cues can be used by mice to remember the location of a dark escape box. The primary time, distance, and strategy taken by the mice to locate the escape box is a measure of learning and memory. Our findings show that mice with tyrosinemia type I were slower to learn than wild-type mice treated with NTBC and made more mistakes, but were capable of learning and storing long-term memory. After learning the location of the target hole, mice with tyrosinemia type I respond differently to a change in location and were less flexible in learning the new target hole location. Our findings suggest that this slower learning and cognitive difference is caused by tyrosinemia type I and not by the treatment with NTBC.
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Affiliation(s)
- Megan A Hillgartner
- Department of Biological Science, University of Alabama in Huntsville, Huntsville, AL, 35899, USA
| | - Sarah B Coker
- Department of Biological Science, University of Alabama in Huntsville, Huntsville, AL, 35899, USA
| | - Ashton E Koenig
- Department of Biological Science, University of Alabama in Huntsville, Huntsville, AL, 35899, USA
| | - Marissa E Moore
- Department of Biological Science, University of Alabama in Huntsville, Huntsville, AL, 35899, USA
| | - Elizabeth Barnby
- College of Nursing, University of Alabama in Huntsville, 1610 Ben Graves Drive, Huntsville, AL, 35899, USA
| | - Gordon G MacGregor
- Department of Biological Science, University of Alabama in Huntsville, Huntsville, AL, 35899, USA.
- , SST 361, 301 Sparkman Dr, Huntsville, AL, 35899, USA.
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Lavandera J, Rodríguez J, Ruspini S, Meiss R, Zuccoli JR, Martínez MDC, Gerez E, Batlle A, Buzaleh AM. Pleiotropic effects of 5-aminolevulinic acid in mouse brain. Biochem Cell Biol 2016; 94:297-305. [DOI: 10.1139/bcb-2015-0094] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
5-Aminolevulinic acid (ALA) seems to be responsible for the neuropsychiatric manifestations of acute intermittent porphyria (AIP). Our aim was to study the effect of ALA on the different metabolic pathways in the mouse brain to enhance our knowledge about the action of this heme precursor on the central nervous system. Heme metabolism, the cholinergic system, the defense enzyme system, and nitric oxide metabolism were evaluated in the encephalon of CF-1 mice receiving a single (40 mg/kg body mass) or multiple doses of ALA (40 mg/kg, every 48 h for 14 days). We subsequently found ALA accumulation in the encephalon of the mice. ALA also altered the brain cholinergic system. After one dose of ALA, a decrease in superoxide dismutase activity and a reduction in glutathione levels were detected, whereas malondialdehyde levels and catalase activity were increased. Heme oxygenase was also increased as an antioxidant response to protect the encephalon against injury. All nitric oxide synthase isoforms were induced by ALA, these changes were more significant for the inducible isoform in glial cells. In conclusion, ALA affected several metabolic pathways in mouse encephalon. Data indicate that a rapid response to oxidative stress was developed; however, with long-term intoxication, the redox balance was probably restored, thereby minimizing oxidative damage.
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Affiliation(s)
- Jimena Lavandera
- Cátedra de Bromatología y Nutrición, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Jorge Rodríguez
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET, Hospital de Clínicas, José de San Martín, Universidad de Buenos Aires, Argentina
| | - Silvina Ruspini
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET, Hospital de Clínicas, José de San Martín, Universidad de Buenos Aires, Argentina
| | - Roberto Meiss
- Departamento de Patología, Instituto de Estudios Oncológicos, Academia Nacional de Medicina, Buenos Aires, Argentina
| | - Johanna Romina Zuccoli
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET, Hospital de Clínicas, José de San Martín, Universidad de Buenos Aires, Argentina
| | - María del Carmen Martínez
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
| | - Esther Gerez
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET, Hospital de Clínicas, José de San Martín, Universidad de Buenos Aires, Argentina
| | - Alcira Batlle
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET, Hospital de Clínicas, José de San Martín, Universidad de Buenos Aires, Argentina
| | - Ana María Buzaleh
- Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET, Hospital de Clínicas, José de San Martín, Universidad de Buenos Aires, Argentina
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
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Stubenhaus BM, Dustin JP, Neverett ER, Beaudry MS, Nadeau LE, Burk-McCoy E, He X, Pearson BJ, Pellettieri J. Light-induced depigmentation in planarians models the pathophysiology of acute porphyrias. eLife 2016; 5. [PMID: 27240733 PMCID: PMC4887210 DOI: 10.7554/elife.14175] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/25/2016] [Indexed: 12/12/2022] Open
Abstract
Porphyrias are disorders of heme metabolism frequently characterized by extreme photosensitivity. This symptom results from accumulation of porphyrins, tetrapyrrole intermediates in heme biosynthesis that generate reactive oxygen species when exposed to light, in the skin of affected individuals. Here we report that in addition to producing an ommochrome body pigment, the planarian flatworm Schmidtea mediterranea generates porphyrins in its subepithelial pigment cells under physiological conditions, and that this leads to pigment cell loss when animals are exposed to intense visible light. Remarkably, porphyrin biosynthesis and light-induced depigmentation are enhanced by starvation, recapitulating a common feature of some porphyrias – decreased nutrient intake precipitates an acute manifestation of the disease. Our results establish planarians as an experimentally tractable animal model for research into the pathophysiology of acute porphyrias, and potentially for the identification of novel pharmacological interventions capable of alleviating porphyrin-mediated photosensitivity or decoupling dieting and fasting from disease pathogenesis. DOI:http://dx.doi.org/10.7554/eLife.14175.001 Porphyrias are rare diseases that involve ring-shaped molecules called porphyrins accumulating in various parts of the body. Porphyrins are produced as part of the normal process that makes an important molecule called heme, which is required to transport oxygen. However, high levels of porphyrins can be toxic. For example, porphyrins deposited in the skin can cause swelling and blistering when the skin is exposed to bright light. Other disease symptoms include neurological issues ranging from anxiety and confusion to seizures or paralysis. It has been speculated that porphyrias may have affected several historical figures, including the artist Vincent van Gogh. In addition to their role in heme production, porphyrins also have other roles. For example, they are used as pigments in the wing feathers of some owls. Researchers are trying to understand more about how organisms regulate porphyrin production so that it might be possible to develop more effective treatments for porphyria in humans. Here, Stubenhaus et al. studied how a flatworm called Schmidtea mediterranea makes porphyrins. A group of undergraduate students noticed that these animals – which are normally brown in color – turned white when they were exposed to sunlight for several days. Stubenhaus et al. found that S. mediterranea makes porphyrins in the pigment cells of its skin using the same genes that make porphyrins in humans. Together with other molecules called ommochromes, the porphyrins give rise to the normal color of this flatworm. However, when the animals are exposed to intense light for extended periods of time, which is unlikely to occur in the wild, porphyrin production leads to loss of the pigment cells. The experiments also show that starvation increases the rate of pigment cell loss in light-exposed flatworms, which mirrors the worsening of disease symptoms some porphyria patients experience when they diet or fast. Stubenhaus et al. propose that flatworms are useful models in which to study the molecular processes that are responsible for porphyrias in humans. Further research is required to determine the exact chemical structure of the porphyrin and ommochrome molecules produced in different flatworm species. Stubenhaus et al. also plan to use flatworms to screen for drugs that could potentially be developed into new treatments for porphyria. DOI:http://dx.doi.org/10.7554/eLife.14175.002
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Affiliation(s)
| | - John P Dustin
- Department of Biology, Keene State College, Keene, United States
| | - Emily R Neverett
- Department of Biology, Keene State College, Keene, United States
| | - Megan S Beaudry
- Department of Biology, Keene State College, Keene, United States
| | - Leanna E Nadeau
- Department of Biology, Keene State College, Keene, United States
| | - Ethan Burk-McCoy
- Department of Biology, Keene State College, Keene, United States
| | - Xinwen He
- The Hospital for Sick Children, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Bret J Pearson
- The Hospital for Sick Children, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Ontario Institute for Cancer Research, Toronto, Canada
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15
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Zhou Y, Notterpek L. Promoting peripheral myelin repair. Exp Neurol 2016; 283:573-80. [PMID: 27079997 DOI: 10.1016/j.expneurol.2016.04.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/30/2016] [Accepted: 04/06/2016] [Indexed: 01/08/2023]
Abstract
Compared to the central nervous system (CNS), peripheral nerves have a remarkable ability to regenerate and remyelinate. This regenerative capacity to a large extent is dependent on and supported by Schwann cells, the myelin-forming glial cells of the peripheral nervous system (PNS). In a variety of paradigms, Schwann cells are critical in the removal of the degenerated tissue, which is followed by remyelination of newly-regenerated axons. This unique plasticity of Schwann cells has been the target of myelin repair strategies in acute injuries and chronic diseases, such as hereditary demyelinating neuropathies. In one approach, the endogenous regenerative capacity of Schwann cells is enhanced through interventions such as exercise, electrical stimulation or pharmacological means. Alternatively, Schwann cells derived from healthy nerves, or engineered from different tissue sources have been transplanted into the PNS to support remyelination. These transplant approaches can then be further enhanced by exercise and/or electrical stimulation, as well as by the inclusion of biomaterial engineered to support glial cell viability and neurite extension. Advances in our basic understanding of peripheral nerve biology, as well as biomaterial engineering, will further improve the functional repair of myelinated peripheral nerves.
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Affiliation(s)
- Ye Zhou
- Departments of Neuroscience and Neurology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, United States
| | - Lucia Notterpek
- Departments of Neuroscience and Neurology, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, United States.
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16
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Pamies D, Hartung T, Hogberg HT. Biological and medical applications of a brain-on-a-chip. Exp Biol Med (Maywood) 2014; 239:1096-1107. [PMID: 24912505 DOI: 10.1177/1535370214537738] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The desire to develop and evaluate drugs as potential countermeasures for biological and chemical threats requires test systems that can also substitute for the clinical trials normally crucial for drug development. Current animal models have limited predictivity for drug efficacy in humans as the large majority of drugs fails in clinical trials. We have limited understanding of the function of the central nervous system and the complexity of the brain, especially during development and neuronal plasticity. Simple in vitro systems do not represent physiology and function of the brain. Moreover, the difficulty of studying interactions between human genetics and environmental factors leads to lack of knowledge about the events that induce neurological diseases. Microphysiological systems (MPS) promise to generate more complex in vitro human models that better simulate the organ's biology and function. MPS combine different cell types in a specific three-dimensional (3D) configuration to simulate organs with a concrete function. The final aim of these MPS is to combine different "organoids" to generate a human-on-a-chip, an approach that would allow studies of complex physiological organ interactions. The recent discovery of induced pluripotent stem cells (iPSCs) gives a range of possibilities allowing cellular studies of individuals with different genetic backgrounds (e.g., human disease models). Application of iPSCs from different donors in MPS gives the opportunity to better understand mechanisms of the disease and can be a novel tool in drug development, toxicology, and medicine. In order to generate a brain-on-a-chip, we have established a 3D model from human iPSCs based on our experience with a 3D rat primary aggregating brain model. After four weeks of differentiation, human 3D aggregates stain positive for different neuronal markers and show higher gene expression of various neuronal differentiation markers compared to 2D cultures. Here we present the applications and challenges of this emerging technology.
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Affiliation(s)
- David Pamies
- Centers for Alternatives to Animal Testing (CAAT) at Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe Street, Baltimore, MD 21205, USA; University of Konstanz, POB 600, Konstanz 78457, Germany
| | - Thomas Hartung
- Centers for Alternatives to Animal Testing (CAAT) at Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe Street, Baltimore, MD 21205, USA; University of Konstanz, POB 600, Konstanz 78457, Germany
| | - Helena T Hogberg
- Centers for Alternatives to Animal Testing (CAAT) at Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe Street, Baltimore, MD 21205, USA; University of Konstanz, POB 600, Konstanz 78457, Germany
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17
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Fratz EJ, Hunter GA, Ferreira GC. Expression of murine 5-aminolevulinate synthase variants causes protoporphyrin IX accumulation and light-induced mammalian cell death. PLoS One 2014; 9:e93078. [PMID: 24718052 PMCID: PMC3981678 DOI: 10.1371/journal.pone.0093078] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 03/02/2014] [Indexed: 01/11/2023] Open
Abstract
5-Aminolevulinate synthase (ALAS; EC 2.3.1.37) catalyzes the first committed step of heme biosynthesis in animals. The erythroid-specific ALAS isozyme (ALAS2) is negatively regulated by heme at the level of mitochondrial import and, in its mature form, certain mutations of the murine ALAS2 active site loop result in increased production of protoporphyrin IX (PPIX), the precursor for heme. Importantly, generation of PPIX is a crucial component in the widely used photodynamic therapies (PDT) of cancer and other dysplasias. ALAS2 variants that cause high levels of PPIX accumulation provide a new means of targeted, and potentially enhanced, photosensitization. In order to assess the prospective utility of ALAS2 variants in PPIX production for PDT, K562 human erythroleukemia cells and HeLa human cervical carcinoma cells were transfected with expression plasmids for ALAS2 variants with greater enzymatic activity than the wild-type enzyme. The levels of accumulated PPIX in ALAS2-expressing cells were analyzed using flow cytometry with fluorescence detection. Further, cells expressing ALAS2 variants were subjected to white light treatments (21–22 kLux) for 10 minutes after which cell viability was determined. Transfection of HeLa cells with expression plasmids for murine ALAS2 variants, specifically for those with mutated mitochondrial presequences and a mutation in the active site loop, caused significant cellular accumulation of PPIX, particularly in the membrane. Light treatments revealed that ALAS2 expression results in an increase in cell death in comparison to aminolevulinic acid (ALA) treatment producing a similar amount of PPIX. The delivery of stable and highly active ALAS2 variants has the potential to expand and improve upon current PDT regimes.
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Affiliation(s)
- Erica J. Fratz
- Department of Molecular Medicine, Morsani College of Medicine, Tampa, Florida, United States of America
| | - Gregory A. Hunter
- Department of Molecular Medicine, Morsani College of Medicine, Tampa, Florida, United States of America
| | - Gloria C. Ferreira
- Department of Molecular Medicine, Morsani College of Medicine, Tampa, Florida, United States of America
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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18
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Lead poisoning and the deceptive recovery of the critically endangered California condor. Proc Natl Acad Sci U S A 2012; 109:11449-54. [PMID: 22733770 DOI: 10.1073/pnas.1203141109] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Endangered species recovery programs seek to restore populations to self-sustaining levels. Nonetheless, many recovering species require continuing management to compensate for persistent threats in their environment. Judging true recovery in the face of this management is often difficult, impeding thorough analysis of the success of conservation programs. We illustrate these challenges with a multidisciplinary study of one of the world's rarest birds-the California condor (Gymnogyps californianus). California condors were brought to the brink of extinction, in part, because of lead poisoning, and lead poisoning remains a significant threat today. We evaluated individual lead-related health effects, the efficacy of current efforts to prevent lead-caused deaths, and the consequences of any reduction in currently intensive management actions. Our results show that condors in California remain chronically exposed to harmful levels of lead; 30% of the annual blood samples collected from condors indicate lead exposure (blood lead ≥ 200 ng/mL) that causes significant subclinical health effects, measured as >60% inhibition of the heme biosynthetic enzyme δ-aminolevulinic acid dehydratase. Furthermore, each year, ∼20% of free-flying birds have blood lead levels (≥450 ng/mL) that indicate the need for clinical intervention to avert morbidity and mortality. Lead isotopic analysis shows that lead-based ammunition is the principle source of lead poisoning in condors. Finally, population models based on condor demographic data show that the condor's apparent recovery is solely because of intensive ongoing management, with the only hope of achieving true recovery dependent on the elimination or substantial reduction of lead poisoning rates.
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Stacpoole PW. The dichloroacetate dilemma: environmental hazard versus therapeutic goldmine--both or neither? ENVIRONMENTAL HEALTH PERSPECTIVES 2011; 119:155-8. [PMID: 20920954 PMCID: PMC3040600 DOI: 10.1289/ehp.1002554] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 10/04/2010] [Indexed: 05/23/2023]
Abstract
BACKGROUND Dichloroacetate (DCA) is known to environmental scientists as a by-product of water chlorination and as a metabolite of industrial solvents, including Superfund chemicals. In contrast, DCA is studied by clinical investigators for its therapeutic potential in several life-threatening conditions, including genetic mitochondrial diseases, pulmonary arterial hypertension, and cancer. Thus, DCA holds an almost unique position at the interface between environmental science and allopathic medicine. OBJECTIVE I critically reviewed laboratory and clinical pharmacological research on DCA to address questions about the current and future status of DCA in relation to human health. DISCUSSION Recent information on the clinical toxicogenetics of DCA is interpreted particularly in light of its use as an investigational drug. Adverse effects from chronic DCA exposure have been identified in several target organs in animals. However, in humans, toxicity has so far been limited to reversible effects on the nervous system and liver. DCA is primarily biotransformed to glyoxylate by the bifunctional enzyme glutathione transferase zeta1 and maleylacetoacetate isomerase (GSTz1/MAAI), which also catalyzes the penultimate step in the phenylalanine and tyrosine catabolic pathway. DCA is a suicide inhibitor of GSTz1/MAAI, which can result in delayed plasma clearance of DCA and the accumulation of potentially toxic tyrosine intermediates. Age and GSTz1/MAAI haplotype can markedly affect the toxicokinetics of DCA in humans and rodents. CONCLUSIONS I have defined new potential avenues of research that focus on discrete human populations that may be at increased health risk or that may receive increased health benefit from chronic exposure to DCA at both environmentally and clinically relevant concentrations.
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Affiliation(s)
- Peter W Stacpoole
- Department of Medicine, Division of Endocrinology and Metabolism, College of Medicine, University of Florida, Gainesville, Florida 32610, USA.
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20
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Unzu C, Sampedro A, Mauleón I, Alegre M, Beattie SG, de Salamanca RE, Snapper J, Twisk J, Petry H, González-Aseguinolaza G, Artieda J, Rodríguez-Pena MS, Prieto J, Fontanellas A. Sustained enzymatic correction by rAAV-mediated liver gene therapy protects against induced motor neuropathy in acute porphyria mice. Mol Ther 2010; 19:243-50. [PMID: 20877347 DOI: 10.1038/mt.2010.210] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Acute intermittent porphyria (AIP) is characterized by a hereditary deficiency of hepatic porphobilinogen deaminase (PBGD) activity. Clinical features are acute neurovisceral attacks accompanied by overproduction of porphyrin precursors in the liver. Recurrent life-threatening attacks can be cured only by liver transplantation. We developed recombinant adeno-associated virus (rAAV) vectors expressing human PBGD protein driven by a liver-specific promoter to provide sustained protection against induced attacks in a predictive model for AIP. Phenobarbital injections in AIP mice induced porphyrin precursor accumulation, functional block of nerve conduction, and progressive loss of large-caliber axons in the sciatic nerve. Hepatocyte transduction showed no gender variation after rAAV2/8 injection, while rAAV2/5 showed lower transduction efficiency in females than males. Full protection against induced phenobarbital-attacks was achieved in animals showing over 10% of hepatocytes expressing high amounts of PBGD. More importantly, sustained hepatic expression of hPBGD protected against loss of large-caliber axons in the sciatic nerve and disturbances in nerve conduction velocity as induced by recurrent phenobarbital administrations. These data show for the first time that porphyrin precursors generated in the liver interfere with motor function. rAAV2/5-hPBGD vector can be produced in sufficient quantity for an intended gene therapy trial in patients with recurrent life-threatening porphyria attacks.
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Affiliation(s)
- Carmen Unzu
- Gene Therapy and Hepatology Area, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain
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AAV8-mediated gene therapy prevents induced biochemical attacks of acute intermittent porphyria and improves neuromotor function. Mol Ther 2009; 18:17-22. [PMID: 19861948 DOI: 10.1038/mt.2009.250] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Acute intermittent porphyria (AIP), an autosomal dominant hepatic porphyria due to half-normal hydroxymethylbilane synthase (HMB-synthase) activity, is manifested by life-threatening acute neurological attacks that are precipitated by factors that induce heme biosynthesis. The acute attacks are currently treated with intravenous hemin, but a more continuous therapy is needed, particularly for patients experiencing frequent attacks. Thus, a recombinant AAV8-based serotype vector expressing murine HMB-synthase driven by liver-specific regulatory elements was generated and its effectiveness to prevent the biochemical induction of an acute attack was evaluated in an AIP mouse model. Intraperitoneal administration of the adeno-associated viral (AAV) vector resulted in a rapid and dose-dependent increase of HMB-synthase activity that was restricted to the liver. Stable expression of hepatic HMB-synthase was achieved and wild-type or greater levels were sustained for 36 weeks. When heme synthesis was periodically induced by a series of phenobarbital injections, the treated mice did not accumulate urinary delta-aminolevulinic acid (ALA) or porphobilinogen (PBG), indicating that the expressed enzyme was functional in vivo and prevented induction of the acute attack. Further, rotarod performance and footprint analyses improved significantly. Thus, liver-directed gene therapy provided successful long-term correction of the hepatic metabolic abnormalities and improved neuromotor function in the murine model of human AIP.
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Abstract
The use of dichloroacetate (DCA) for treating patients with mitochondrial diseases is limited by the induction of peripheral neuropathy. The mechanisms of DCA-induced neuropathy are not known. Oral DCA treatment (50-500 mg/kg per day for up to 16 weeks) induced tactile allodynia in both juvenile and adult rats; concurrent thermal hypoalgesia developed at higher doses. Both juvenile and adult rats treated with DCA developed nerve conduction slowing that was more pronounced in adult rats. No overt axonal or glial cell abnormalities were identified in peripheral nerves or spinal cord of any DCA-treated rat, but morphometric analysis identified a reduction of mean axonal caliber of peripheral nerve myelinated fibers. Dichloroacetate treatment also caused accumulation of oxidative stress markers in the nerves. These data indicate that behavioral, functional, and structural indices of peripheral neuropathy may be induced in both juvenile and adult rats treated with DCA at doses similar to those in clinical use. Dichloroacetate-induced peripheral neuropathy primarily afflicts axons and involves both metabolic and structural disorders. The DCA-treated rat may provide insight into the pathogenesis of this peripheral neuropathy and facilitate development of adjuvant therapeutics to prevent this disorder that currently restricts the clinical use of DCA.
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Abstract
Despite improvements in the identification of causes of peripheral neuropathy, idiopathic polyneuropathy remains common. Medication and toxic neuropathy account for a small but important percentage of potentially preventable or reversible causes of neuropathy. New drugs that can induce neuropathy have been approved over the past several years, including the anticancer agents bortezomib, ixabepilone, and oxaliplatin. We review the neurotoxic effects of tumor necrosis factor-alpha blockers infliximab and etanercept, the inflammatory arthritis agent leflunomide, and the antibiotic linezolid. The controversy of statin-induced neuropathy continues to unfold; the large Fremantle Diabetes Study has suggested that statins may have neuroprotective effects. Dichloroacetate is a promising agent for lactic acidosis-associated disorders, but toxic neuropathy is a treatment-limiting factor. We also describe a progressive inflammatory neuropathy in swine slaughterhouse workers that appears to be a toxin-induced immune response.
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