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Pontremoli R, Ghinatti MC, Barnini C. Asymptomatic hyperuricemia and cardiovascular mortality: A matter of mechanisms? Eur J Intern Med 2024; 121:42-43. [PMID: 38072686 DOI: 10.1016/j.ejim.2023.11.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 11/30/2023] [Indexed: 03/08/2024]
Affiliation(s)
- Roberto Pontremoli
- Department of Internal Medicine and Medical Specialties, University of Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy.
| | | | - Cecilia Barnini
- Department of Internal Medicine and Medical Specialties, University of Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy; Innsbruck Medical University, Innsbruck, Austria
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2
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Johnson RJ, Sánchez-Lozada LG, Lanaspa MA. The fructose survival hypothesis as a mechanism for unifying the various obesity hypotheses. Obesity (Silver Spring) 2024; 32:12-22. [PMID: 37846155 DOI: 10.1002/oby.23920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/13/2023] [Accepted: 07/31/2023] [Indexed: 10/18/2023]
Abstract
The pathogenesis of obesity remains contested. Although genetics is important, the rapid rise in obesity with Western culture and diet suggests an environmental component. Today, some of the major hypotheses for obesity include the energy balance hypothesis, the carbohydrate-insulin model, the protein-leverage hypothesis, and the seed oil hypothesis. Each hypothesis has its own support, creating controversy over their respective roles in driving obesity. Here we propose that all hypotheses are largely correct and can be unified by another dietary hypothesis, the fructose survival hypothesis. Fructose is unique in resetting ATP levels to a lower level in the cell as a consequence of suppressing mitochondrial function, while blocking the replacement of ATP from fat. The low intracellular ATP levels result in carbohydrate-dependent hunger, impaired satiety (leptin resistance), and metabolic effects that result in the increased intake of energy-dense fats. This hypothesis emphasizes the unique role of carbohydrates in stimulating intake while fat provides the main source of energy. Thus, obesity is a disorder of energy metabolism, in which there is low usable energy (ATP) in the setting of elevated total energy. This leads to metabolic effects independent of excess energy while the excess energy drives weight gain.
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Affiliation(s)
- Richard J Johnson
- Division of Nephrology, Rocky Mountain VA Medical Center, Aurora, Colorado, USA
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Laura G Sánchez-Lozada
- Laboratory of Renal Physiopathology, Instituto Nacional de Cardiologia Ignacio Chavez, Mexico City, Mexico
| | - Miguel A Lanaspa
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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3
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Roman YM. The Role of Uric Acid in Human Health: Insights from the Uricase Gene. J Pers Med 2023; 13:1409. [PMID: 37763176 PMCID: PMC10532990 DOI: 10.3390/jpm13091409] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 09/17/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023] Open
Abstract
Uric acid is the final product of purine metabolism and is converted to allantoin in most mammals via the uricase enzyme. The accumulation of loss of function mutations in the uricase gene rendered hominoids (apes and humans) to have higher urate concentrations compared to other mammals. The loss of human uricase activity may have allowed humans to survive environmental stressors, evolution bottlenecks, and life-threatening pathogens. While high urate levels may contribute to developing gout and cardiometabolic disorders such as hypertension and insulin resistance, low urate levels may increase the risk for neurodegenerative diseases. The double-edged sword effect of uric acid has resurrected a growing interest in urate's antioxidant role and the uricase enzyme's role in modulating the risk of obesity. Characterizing both the effect of uric acid levels and the uricase enzyme in different animal models may provide new insights into the potential therapeutic benefits of uric acid and novel uricase-based therapy.
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Affiliation(s)
- Youssef M Roman
- Department of Pharmacotherapy & Outcomes Science, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298, USA
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Johnson RJ, Lanaspa MA, Sanchez-Lozada LG, Tolan D, Nakagawa T, Ishimoto T, Andres-Hernando A, Rodriguez-Iturbe B, Stenvinkel P. The fructose survival hypothesis for obesity. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220230. [PMID: 37482773 PMCID: PMC10363705 DOI: 10.1098/rstb.2022.0230] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 05/04/2023] [Indexed: 07/25/2023] Open
Abstract
The fructose survival hypothesis proposes that obesity and metabolic disorders may have developed from over-stimulation of an evolutionary-based biologic response (survival switch) that aims to protect animals in advance of crisis. The response is characterized by hunger, thirst, foraging, weight gain, fat accumulation, insulin resistance, systemic inflammation and increased blood pressure. The process is initiated by the ingestion of fructose or by stimulating endogenous fructose production via the polyol pathway. Unlike other nutrients, fructose reduces the active energy (adenosine triphosphate) in the cell, while blocking its regeneration from fat stores. This is mediated by intracellular uric acid, mitochondrial oxidative stress, the inhibition of AMP kinase and stimulation of vasopressin. Mitochondrial oxidative phosphorylation is suppressed, and glycolysis stimulated. While this response is aimed to be modest and short-lived, the response in humans is exaggerated due to gain of 'thrifty genes' coupled with a western diet rich in foods that contain or generate fructose. We propose excessive fructose metabolism not only explains obesity but the epidemics of diabetes, hypertension, non-alcoholic fatty liver disease, obesity-associated cancers, vascular and Alzheimer's dementia, and even ageing. Moreover, the hypothesis unites current hypotheses on obesity. Reducing activation and/or blocking this pathway and stimulating mitochondrial regeneration may benefit health-span. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.
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Affiliation(s)
- Richard J. Johnson
- Department of Medicine, University of Colorado Anschutz Medical Center, Aurora, CO 80016, USA
| | - Miguel A. Lanaspa
- Department of Medicine, University of Colorado Anschutz Medical Center, Aurora, CO 80016, USA
| | - L. Gabriela Sanchez-Lozada
- Department of Cardio-Renal Physiopathology, Instituto Nacional de Cardiología ‘Ignacio Chavez’, Mexico City 14080, Mexico
| | - Dean Tolan
- Biology Department, Boston University, Boston, MA 02215, USA
| | - Takahiko Nakagawa
- Department of Nephrology, Rakuwakai-Otowa Hospital, Kyoto 607-8062, Japan
| | - Takuji Ishimoto
- Department of Nephrology and Rheumatology, Aichi Medical University, Aichi 480-1103, Japan
| | - Ana Andres-Hernando
- Department of Medicine, University of Colorado Anschutz Medical Center, Aurora, CO 80016, USA
| | - Bernardo Rodriguez-Iturbe
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición ‘Salvador Zubirán’, Mexico City 14080, Mexico
| | - Peter Stenvinkel
- Department of Renal Medicine, Karolinska Institutet, Stockholm 171 77, Sweden
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Liu Y, Jarman JB, Low YS, Augustijn HE, Huang S, Chen H, DeFeo ME, Sekiba K, Hou BH, Meng X, Weakley AM, Cabrera AV, Zhou Z, van Wezel G, Medema MH, Ganesan C, Pao AC, Gombar S, Dodd D. A widely distributed gene cluster compensates for uricase loss in hominids. Cell 2023; 186:3400-3413.e20. [PMID: 37541197 PMCID: PMC10421625 DOI: 10.1016/j.cell.2023.06.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 03/22/2023] [Accepted: 06/19/2023] [Indexed: 08/06/2023]
Abstract
Approximately 15% of US adults have circulating levels of uric acid above its solubility limit, which is causally linked to the disease gout. In most mammals, uric acid elimination is facilitated by the enzyme uricase. However, human uricase is a pseudogene, having been inactivated early in hominid evolution. Though it has long been known that uric acid is eliminated in the gut, the role of the gut microbiota in hyperuricemia has not been studied. Here, we identify a widely distributed bacterial gene cluster that encodes a pathway for uric acid degradation. Stable isotope tracing demonstrates that gut bacteria metabolize uric acid to xanthine or short chain fatty acids. Ablation of the microbiota in uricase-deficient mice causes severe hyperuricemia, and anaerobe-targeted antibiotics increase the risk of gout in humans. These data reveal a role for the gut microbiota in uric acid excretion and highlight the potential for microbiome-targeted therapeutics in hyperuricemia.
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Affiliation(s)
- Yuanyuan Liu
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - J Bryce Jarman
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | - Hannah E Augustijn
- Bioinformatics Group, Wageningen University, Wageningen, the Netherlands; Institute of Biology, Leiden University, Leiden, the Netherlands
| | - Steven Huang
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Haoqing Chen
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mary E DeFeo
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kazuma Sekiba
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Bi-Huei Hou
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Xiandong Meng
- ChEM-H Institute, Stanford University, Stanford, CA 94305, USA
| | | | | | - Zhiwei Zhou
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Gilles van Wezel
- Institute of Biology, Leiden University, Leiden, the Netherlands; Netherlands Institute of Ecology, Wageningen, the Netherlands
| | - Marnix H Medema
- Bioinformatics Group, Wageningen University, Wageningen, the Netherlands; Institute of Biology, Leiden University, Leiden, the Netherlands
| | - Calyani Ganesan
- Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alan C Pao
- Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Urology, Stanford University School of Medicine, Stanford, CA 94305, USA; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, USA
| | - Saurabh Gombar
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA; Atropos Health, Palo Alto, CA, USA
| | - Dylan Dodd
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Sánchez-Lozada LG, Madero M, Mazzali M, Feig DI, Nakagawa T, Lanaspa MA, Kanbay M, Kuwabara M, Rodriguez-Iturbe B, Johnson RJ. Sugar, salt, immunity and the cause of primary hypertension. Clin Kidney J 2023; 16:1239-1248. [PMID: 37529651 PMCID: PMC10387395 DOI: 10.1093/ckj/sfad058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Indexed: 08/03/2023] Open
Abstract
Despite its discovery more than 150 years ago, the cause of primary hypertension remains unknown. Most studies suggest that hypertension involves genetic, congenital or acquired risk factors that result in a relative inability of the kidney to excrete salt (sodium chloride) in the kidneys. Here we review recent studies that suggest there may be two phases, with an initial phase driven by renal vasoconstriction that causes low-grade ischemia to the kidney, followed by the infiltration of immune cells that leads to a local autoimmune reaction that maintains the renal vasoconstriction. Evidence suggests that multiple mechanisms could trigger the initial renal vasoconstriction, but one way may involve fructose that is provided in the diet (such as from table sugar or high fructose corn syrup) or produced endogenously. The fructose metabolism increases intracellular uric acid, which recruits NADPH oxidase to the mitochondria while inhibiting AMP-activated protein kinase. A drop in intracellular ATP level occurs, triggering a survival response. Leptin levels rise, triggering activation of the sympathetic central nervous system, while vasopressin levels rise, causing vasoconstriction in its own right and stimulating aldosterone production via the vasopressin 1b receptor. Low-grade renal injury and autoimmune-mediated inflammation occur. High-salt diets can amplify this process by raising osmolality and triggering more fructose production. Thus, primary hypertension may result from the overactivation of a survival response triggered by fructose metabolism. Restricting salt and sugar and hydrating with ample water may be helpful in the prevention of primary hypertension.
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Affiliation(s)
- Laura G Sánchez-Lozada
- Department of Cardio-Renal Physiopathology, Instituto Nacional de Cardiología “Ignacio Chavez”, Mexico City, Mexico
| | - Magdalena Madero
- Division of Nephrology, Department of Medicine, Instituto Nacional de Cardiología “Ignacio Chavez”, Mexico City, Mexico
| | - Marilda Mazzali
- Division of Nephrology, University of Campinas, São Paulo, Brazil
| | - Daniel I Feig
- Division of Pediatric Nephrology, University of Alabama, Birmingham, AL, USA
| | | | - Miguel A Lanaspa
- Department of Medicine, University of Colorado Anschutz Medical Center, Aurora, CO, USA
| | - Mehmet Kanbay
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | | | - Bernardo Rodriguez-Iturbe
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”, Mexico City
| | - Richard J Johnson
- Department of Medicine, University of Colorado Anschutz Medical Center, Aurora, CO, USA
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Inhibition of Succinate Dehydrogenase by Pesticides (SDHIs) and Energy Metabolism. Int J Mol Sci 2023; 24:ijms24044045. [PMID: 36835457 PMCID: PMC9962667 DOI: 10.3390/ijms24044045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/07/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
Succinate dehydrogenase (SDH) is one of the enzymes of the tricarboxylic acid cycle (Krebs cycle) and complex II of the mitochondrial respiratory chain. A class of fungicides (SDHIs) targets the complex II reaction in the SDH. A large number of those in use have been shown to inhibit SDH in other phyla, including humans. This raises questions about possible effects on human health and non-target organisms in the environment. The present document will address metabolic consequences in mammals; it is neither a review on SDH nor is it about the toxicology of SDHIs. Most clinically relevant observations are linked to a severe decrease in SDH activity. Here we shall examine the mechanisms for compensating a loss of SDH activity and their possible weaknesses or adverse consequences. It can be expected that a mild inhibition of SDH will be compensated by the kinetic properties of this enzyme, but this implies a proportionate increase in succinate concentration. This would be relevant for succinate signaling and epigenetics (not reviewed here). With regard to metabolism, exposure of the liver to SDHIs would increase the risk for non-alcoholic fatty liver disease (NAFLD). Higher levels of inhibition may be compensated by modification of metabolic fluxes with net production of succinate. SDHIs are much more soluble in lipids than in water; consequently, a different diet composition between laboratory animals and humans is expected to influence their absorption.
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