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Yan P, Liu J, Li Z, Wang J, Zhu Z, Wang L, Yu G. Glycolysis Reprogramming in Idiopathic Pulmonary Fibrosis: Unveiling the Mystery of Lactate in the Lung. Int J Mol Sci 2023; 25:315. [PMID: 38203486 PMCID: PMC10779333 DOI: 10.3390/ijms25010315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/17/2023] [Accepted: 12/23/2023] [Indexed: 01/12/2024] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease characterized by excessive deposition of fibrotic connective tissue in the lungs. Emerging evidence suggests that metabolic alterations, particularly glycolysis reprogramming, play a crucial role in the pathogenesis of IPF. Lactate, once considered a metabolic waste product, is now recognized as a signaling molecule involved in various cellular processes. In the context of IPF, lactate has been shown to promote fibroblast activation, myofibroblast differentiation, and extracellular matrix remodeling. Furthermore, lactate can modulate immune responses and contribute to the pro-inflammatory microenvironment observed in IPF. In addition, lactate has been implicated in the crosstalk between different cell types involved in IPF; it can influence cell-cell communication, cytokine production, and the activation of profibrotic signaling pathways. This review aims to summarize the current research progress on the role of glycolytic reprogramming and lactate in IPF and its potential implications to clarify the role of lactate in IPF and to provide a reference and direction for future research. In conclusion, elucidating the intricate interplay between lactate metabolism and fibrotic processes may lead to the development of innovative therapeutic strategies for IPF.
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Affiliation(s)
| | | | | | | | | | - Lan Wang
- State Key Laboratory of Cell Differentiation and Regulation, Henan Center for Outstanding Overseas Scientists of Organ Fibrosis, Pingyuan Laboratory, College of Life Science, Henan Normal University, Xinxiang 453007, China; (P.Y.); (J.L.); (Z.L.); (J.W.); (Z.Z.)
| | - Guoying Yu
- State Key Laboratory of Cell Differentiation and Regulation, Henan Center for Outstanding Overseas Scientists of Organ Fibrosis, Pingyuan Laboratory, College of Life Science, Henan Normal University, Xinxiang 453007, China; (P.Y.); (J.L.); (Z.L.); (J.W.); (Z.Z.)
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2
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Brooks GA. What the Lactate Shuttle Means for Sports Nutrition. Nutrients 2023; 15:2178. [PMID: 37432330 DOI: 10.3390/nu15092178] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/29/2023] [Accepted: 04/30/2023] [Indexed: 07/12/2023] Open
Abstract
The discovery of the lactate shuttle (LS) mechanism may have two opposite perceptions, It may mean very little, because the body normally and inexorably uses the LS mechanism. On the contrary, one may support the viewpoint that understanding the LS mechanism offers immense opportunities for understanding nutrition and metabolism in general, as well as in a sports nutrition supplementation setting. In fact, regardless of the specific form of the carbohydrate (CHO) nutrient taken, the bodily CHO energy flux is from a hexose sugar glucose or glucose polymer (glycogen and starches) to lactate with subsequent somatic tissue oxidation or storage as liver glycogen. In fact, because oxygen and lactate flow together through the circulation to sites of utilization, the bodily carbon energy flow is essentially the lactate disposal rate. Consequently, one can consume glucose or glucose polymers in various forms (glycogen, maltodextrin, potato, corn starch, and fructose or high-fructose corn syrup), and the intestinal wall, liver, integument, and active and inactive muscles make lactate which is the chief energy fuel for red skeletal muscle, heart, brain, erythrocytes, and kidneys. Therefore, if one wants to hasten the delivery of CHO energy delivery, instead of providing CHO foods, supplementation with lactate nutrient compounds can augment body energy flow.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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3
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Bae H, Lam K, Jang C. Metabolic flux between organs measured by arteriovenous metabolite gradients. Exp Mol Med 2022; 54:1354-1366. [PMID: 36075951 PMCID: PMC9534916 DOI: 10.1038/s12276-022-00803-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/15/2022] [Accepted: 03/04/2022] [Indexed: 12/15/2022] Open
Abstract
Mammalian organs convert dietary nutrients into circulating metabolites and share them to maintain whole-body metabolic homeostasis. While the concentrations of circulating metabolites have been frequently measured in a variety of pathophysiological conditions, the exchange flux of circulating metabolites between organs is not easily measurable due to technical difficulties. Isotope tracing is useful for measuring such fluxes for a metabolite of interest, but the shuffling of isotopic atoms between metabolites requires mathematical modeling. Arteriovenous metabolite gradient measurements can complement isotope tracing to infer organ-specific net fluxes of many metabolites simultaneously. Here, we review the historical development of arteriovenous measurements and discuss their advantages and limitations with key example studies that have revealed metabolite exchange flux between organs in diverse pathophysiological contexts.
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Affiliation(s)
- Hosung Bae
- Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Katie Lam
- Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Cholsoon Jang
- Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA.
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4
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Brooks GA, Osmond AD, Leija RG, Curl CC, Arevalo JA, Duong JJ, Horning MA. The blood lactate/pyruvate equilibrium affair. Am J Physiol Endocrinol Metab 2022; 322:E34-E43. [PMID: 34719944 PMCID: PMC8722269 DOI: 10.1152/ajpendo.00270.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Lactate Shuttle hypothesis is supported by a variety of techniques including mass spectrometry analytics following infusion of carbon-labeled isotopic tracers. However, there has been controversy over whether lactate tracers measure lactate (L) or pyruvate (P) turnover. Here, we review the analytical errors, use of inappropriate tissue and animal models, failure to consider L and P pool sizes in modeling results, inappropriate tracer and blood sampling sites, and failure to anticipate roles of heart and lung parenchyma on L⇔P interactions. With support from magnetic resonance spectroscopy (MRS) and immunocytochemistry, we conclude that carbon-labeled lactate tracers can be used to quantitate lactate fluxes.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Adam D Osmond
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Robert G Leija
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Casey C Curl
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Jose A Arevalo
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Justin J Duong
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Michael A Horning
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
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5
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Lee TY. Lactate: a multifunctional signaling molecule. Yeungnam Univ J Med 2021; 38:183-193. [PMID: 33596629 PMCID: PMC8225492 DOI: 10.12701/yujm.2020.00892] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 01/25/2021] [Indexed: 12/23/2022] Open
Abstract
Since its discovery in 1780, lactate has long been misunderstood as a waste by-product of anaerobic glycolysis with multiple deleterious effects. Owing to the lactate shuttle concept introduced in the early 1980s, a paradigm shift began to occur. Increasing evidence indicates that lactate is a coordinator of whole-body metabolism. Lactate is not only a readily accessible fuel that is shuttled throughout the body but also a metabolic buffer that bridges glycolysis and oxidative phosphorylation between cells and intracellular compartments. Lactate also acts as a multifunctional signaling molecule through receptors expressed in various cells and tissues, resulting in diverse biological consequences including decreased lipolysis, immune regulation, anti-inflammation, wound healing, and enhanced exercise performance in association with the gut microbiome. Furthermore, lactate contributes to epigenetic gene regulation by lactylating lysine residues of histones, accounting for its key role in immune modulation and maintenance of homeostasis.
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Affiliation(s)
- Tae-Yoon Lee
- Department of Microbiology, Yeungnam University College of Medicine, Daegu, Korea
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6
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Brooks GA, Arevalo JA, Osmond AD, Leija RG, Curl CC, Tovar AP. Lactate in contemporary biology: a phoenix risen. J Physiol 2021; 600:1229-1251. [PMID: 33566386 PMCID: PMC9188361 DOI: 10.1113/jp280955] [Citation(s) in RCA: 90] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/21/2021] [Indexed: 12/13/2022] Open
Abstract
After a century, it's time to turn the page on understanding of lactate metabolism and appreciate that lactate shuttling is an important component of intermediary metabolism in vivo. Cell‐cell and intracellular lactate shuttles fulfil purposes of energy substrate production and distribution, as well as cell signalling under fully aerobic conditions. Recognition of lactate shuttling came first in studies of physical exercise where the roles of driver (producer) and recipient (consumer) cells and tissues were obvious. Moreover, the presence of lactate shuttling as part of postprandial glucose disposal and satiety signalling has been recognized. Mitochondrial respiration creates the physiological sink for lactate disposal in vivo. Repeated lactate exposure from regular exercise results in adaptive processes such as mitochondrial biogenesis and other healthful circulatory and neurological characteristics such as improved physical work capacity, metabolic flexibility, learning, and memory. The importance of lactate and lactate shuttling in healthful living is further emphasized when lactate signalling and shuttling are dysregulated as occurs in particular illnesses and injuries. Like a phoenix, lactate has risen to major importance in 21st century biology.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Jose A Arevalo
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Adam D Osmond
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Robert G Leija
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Casey C Curl
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Ashley P Tovar
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
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7
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Pourfathi M, Xin Y, Rosalino M, Cereda M, Kadlecek S, Duncan I, Profka H, Hamedani H, Siddiqui S, Ruppert K, Chatterjee S, Rizi RR. Pulmonary pyruvate metabolism as an index of inflammation and injury in a rat model of acute respiratory distress syndrome. NMR IN BIOMEDICINE 2020; 33:e4380. [PMID: 32681670 DOI: 10.1002/nbm.4380] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 06/15/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
Increased pulmonary lactate production is correlated with severity of lung injury and outcome in acute respiratory distress syndrome (ARDS) patients. This study was conducted to investigate the relative contributions of inflammation and hypoxia to the lung's metabolic shift to glycolysis in an experimental animal model of ARDS using hyperpolarized (HP) 13 C MRI. Fifty-three intubated and mechanically ventilated male rats were imaged using HP 13 C MRI before, and 1, 2.5 and 4 hours after saline (sham) or hydrochloric acid (HCl; 0.5 ml/kg) instillation in the trachea, followed by protective and nonprotective mechanical ventilation (HCl-PEEP and HCl-ZEEP) or the start of moderate or severe hypoxia (Hyp90 and Hyp75 groups). Pulmonary and cardiac HP lactate-to-pyruvate ratios were compared among groups for different time points. Postmortem histology and immunofluorescence were used to assess lung injury severity and quantify the expression of innate inflammatory markers and local tissue hypoxia. HP pulmonary lactate-to-pyruvate ratio progressively increased in rats with lung injury and moderate hypoxia (HCl-ZEEP), with no significant change in pulmonary lactate-to-pyruvate ratio in noninjured but moderately hypoxic rats (Hyp90). Pulmonary lactate-to-pyruvate ratio was elevated in otherwise healthy lung tissue only in severe systemic hypoxia (Hyp75 group). ex vivo histological and immunopathological assessment further confirmed the link between elevated glycolysis and the recruitment into and presence of activated neutrophils in injured lungs. HP lactate-to-pyruvate ratio is elevated in injured lungs predominantly as a result of increased glycolysis in activated inflammatory cells, but can also increase due to severe inflammation-induced hypoxia.
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Affiliation(s)
- Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Michael Rosalino
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Maurizio Cereda
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ian Duncan
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sarmad Siddiqui
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Shampa Chatterjee
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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8
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Brooks GA. The tortuous path of lactate shuttle discovery: From cinders and boards to the lab and ICU. JOURNAL OF SPORT AND HEALTH SCIENCE 2020; 9:446-460. [PMID: 32444344 PMCID: PMC7498672 DOI: 10.1016/j.jshs.2020.02.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/04/2019] [Accepted: 12/16/2019] [Indexed: 05/11/2023]
Abstract
Once thought to be a waste product of oxygen limited (anaerobic) metabolism, lactate is now known to form continuously under fully oxygenated (aerobic) conditions. Lactate shuttling between producer (driver) and consumer cells fulfills at least 3 purposes; lactate is: (1) a major energy source, (2) the major gluconeogenic precursor, and (3) a signaling molecule. The Lactate Shuttle theory is applicable to diverse fields such as sports nutrition and hydration, resuscitation from acidosis and Dengue, treatment of traumatic brain injury, maintenance of glycemia, reduction of inflammation, cardiac support in heart failure and following a myocardial infarction, and to improve cognition. Yet, dysregulated lactate shuttling disrupts metabolic flexibility, and worse, supports oncogenesis. Lactate production in cancer (the Warburg effect) is involved in all main sequela for carcinogenesis: angiogenesis, immune escape, cell migration, metastasis, and self-sufficient metabolism. The history of the tortuous path of discovery in lactate metabolism and shuttling was discussed in the 2019 American College of Sports Medicine Joseph B. Wolffe Lecture in Orlando, FL.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California Berkeley, CA 94720-3140, USA.
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9
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Pourfathi M, Kadlecek SJ, Chatterjee S, Rizi RR. Metabolic Imaging and Biological Assessment: Platforms to Evaluate Acute Lung Injury and Inflammation. Front Physiol 2020; 11:937. [PMID: 32982768 PMCID: PMC7487972 DOI: 10.3389/fphys.2020.00937] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/13/2020] [Indexed: 12/26/2022] Open
Abstract
Pulmonary inflammation is a hallmark of several pulmonary disorders including acute lung injury and acute respiratory distress syndrome. Moreover, it has been shown that patients with hyperinflammatory phenotype have a significantly higher mortality rate. Despite this, current therapeutic approaches focus on managing the injury rather than subsiding the inflammatory burden of the lung. This is because of the lack of appropriate non-invasive biomarkers that can be used clinically to assess pulmonary inflammation. In this review, we discuss two metabolic imaging tools that can be used to non-invasively assess lung inflammation. The first method, Positron Emission Tomography (PET), is widely used in clinical oncology and quantifies flux in metabolic pathways by measuring uptake of a radiolabeled molecule into the cells. The second method, hyperpolarized 13C MRI, is an emerging tool that interrogates the branching points of the metabolic pathways to quantify the fate of metabolites. We discuss the differences and similarities between these techniques and discuss their clinical applications.
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Affiliation(s)
- Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Stephen J. Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Shampa Chatterjee
- Department of Physiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Rahim R. Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States
- *Correspondence: Rahim R. Rizi,
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10
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Feasibility of lung microdialysis to assess metabolism during clinical ex vivo lung perfusion. J Heart Lung Transplant 2019; 38:267-276. [DOI: 10.1016/j.healun.2018.12.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 12/12/2018] [Accepted: 12/16/2018] [Indexed: 11/20/2022] Open
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11
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The Science and Translation of Lactate Shuttle Theory. Cell Metab 2018; 27:757-785. [PMID: 29617642 DOI: 10.1016/j.cmet.2018.03.008] [Citation(s) in RCA: 646] [Impact Index Per Article: 107.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/06/2018] [Accepted: 03/16/2018] [Indexed: 02/07/2023]
Abstract
Once thought to be a waste product of anaerobic metabolism, lactate is now known to form continuously under aerobic conditions. Shuttling between producer and consumer cells fulfills at least three purposes for lactate: (1) a major energy source, (2) the major gluconeogenic precursor, and (3) a signaling molecule. "Lactate shuttle" (LS) concepts describe the roles of lactate in delivery of oxidative and gluconeogenic substrates as well as in cell signaling. In medicine, it has long been recognized that the elevation of blood lactate correlates with illness or injury severity. However, with lactate shuttle theory in mind, some clinicians are now appreciating lactatemia as a "strain" and not a "stress" biomarker. In fact, clinical studies are utilizing lactate to treat pro-inflammatory conditions and to deliver optimal fuel for working muscles in sports medicine. The above, as well as historic and recent studies of lactate metabolism and shuttling, are discussed in the following review.
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12
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Pourfathi M, Xin Y, Kadlecek SJ, Cereda MF, Profka H, Hamedani H, Siddiqui SM, Ruppert K, Drachman NA, Rajaei JN, Rizi RR. In vivo imaging of the progression of acute lung injury using hyperpolarized [1- 13 C] pyruvate. Magn Reson Med 2017; 78:2106-2115. [PMID: 28074497 DOI: 10.1002/mrm.26604] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/29/2016] [Accepted: 12/20/2016] [Indexed: 12/19/2022]
Abstract
PURPOSE To investigate pulmonary metabolic alterations during progression of acute lung injury. METHODS Using hyperpolarized [1-13 C] pyruvate imaging, we measured pulmonary lactate and pyruvate in 15 ventilated rats 1, 2, and 4 h after initiation of mechanical ventilation. Lung compliance was used as a marker for injury progression. 5 untreated rats were used as controls; 5 rats (injured-1) received 1 ml/kg and another 5 rats (injured-2) received 2 ml/kg hydrochloric acid (pH 1.25) in the trachea at 70 min. RESULTS The mean lactate-to-pyruvate ratio of the injured-1 cohort was 0.15 ± 0.02 and 0.15 ± 0.03 at baseline and 1 h after the injury, and significantly increased from the baseline value 3 h after the injury to 0.23 ± 0.02 (P = 0.002). The mean lactate-to-pyruvate ratio of the injured-2 cohort decreased from 0.14 ± 0.03 at baseline to 0.08 ± 0.02 1 h after the injury and further decreased to 0.07 ± 0.02 (P = 0.08) 3 h after injury. No significant change was observed in the control group. Compliance in both injured groups decreased significantly after the injury (P < 0.01). CONCLUSIONS Our findings suggest that in severe cases of lung injury, edema and hyperperfusion in the injured lung tissue may complicate interpretation of the pulmonary lactate-to-pyruvate ratio as a marker of inflammation. However, combining the lactate-to-pyruvate ratio with pulmonary compliance provides more insight into the progression of the injury and its severity. Magn Reson Med 78:2106-2115, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stephen J Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Maurizio F Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sarmad M Siddiqui
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nicholas A Drachman
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jennia N Rajaei
- School of Medicine, Stanford University, Stanford, California, USA
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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13
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Glenn TC, Martin NA, McArthur DL, Hovda DA, Vespa P, Johnson ML, Horning MA, Brooks GA. Endogenous Nutritive Support after Traumatic Brain Injury: Peripheral Lactate Production for Glucose Supply via Gluconeogenesis. J Neurotrauma 2015; 32:811-9. [PMID: 25279664 PMCID: PMC4530391 DOI: 10.1089/neu.2014.3482] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We evaluated the hypothesis that nutritive needs of injured brains are supported by large and coordinated increases in lactate shuttling throughout the body. To that end, we used dual isotope tracer ([6,6-(2)H2]glucose, i.e., D2-glucose, and [3-(13)C]lactate) techniques involving central venous tracer infusion along with cerebral (arterial [art] and jugular bulb [JB]) blood sampling. Patients with traumatic brain injury (TBI) who had nonpenetrating head injuries (n=12, all male) were entered into the study after consent of patients' legal representatives. Written and informed consent was obtained from healthy controls (n=6, including one female). As in previous investigations, the cerebral metabolic rate (CMR) for glucose was suppressed after TBI. Near normal arterial glucose and lactate levels in patients studied 5.7±2.2 days (range of days 2-10) post-injury, however, belied a 71% increase in systemic lactate production, compared with control, that was largely cleared by greater (hepatic+renal) glucose production. After TBI, gluconeogenesis from lactate clearance accounted for 67.1% of glucose rate of appearance (Ra), which was compared with 15.2% in healthy controls. We conclude that elevations in blood glucose concentration after TBI result from a massive mobilization of lactate from corporeal glycogen reserves. This previously unrecognized mobilization of lactate subserves hepatic and renal gluconeogenesis. As such, a lactate shuttle mechanism indirectly makes substrate available for the body and its essential organs, including the brain, after trauma. In addition, when elevations in arterial lactate concentration occur after TBI, lactate shuttling may provide substrate directly to vital organs of the body, including the injured brain.
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Affiliation(s)
- Thomas C. Glenn
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
- Division of Neurosurgery, University of California, Los Angeles (UCLA), UCLA Center for Health Sciences, Los Angeles, California
| | - Neil A. Martin
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
- Division of Neurosurgery, University of California, Los Angeles (UCLA), UCLA Center for Health Sciences, Los Angeles, California
| | - David L. McArthur
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
| | - David A. Hovda
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
| | - Paul Vespa
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
| | - Matthew L. Johnson
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California
| | - Michael A. Horning
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California
| | - George A. Brooks
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California
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14
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Glenn TC, Martin NA, Horning MA, McArthur DL, Hovda DA, Vespa P, Brooks GA. Lactate: brain fuel in human traumatic brain injury: a comparison with normal healthy control subjects. J Neurotrauma 2015; 32:820-32. [PMID: 25594628 PMCID: PMC4530406 DOI: 10.1089/neu.2014.3483] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We evaluated the hypothesis that lactate shuttling helps support the nutritive needs of injured brains. To that end, we utilized dual isotope tracer [6,6-(2)H2]glucose, that is, D2-glucose, and [3-(13)C]lactate techniques involving arm vein tracer infusion along with simultaneous cerebral (arterial [art] and jugular bulb [JB]) blood sampling. Traumatic brain injury (TBI) patients with nonpenetrating brain injuries (n=12) were entered into the study following consent of patients' legal representatives. Written and informed consent was obtained from control volunteers (n=6). Patients were studied 5.7±2.2 (mean±SD) days post-injury; during periods when arterial glucose concentration tended to be higher in TBI patients. As in previous investigations, the cerebral metabolic rate for glucose (CMRgluc, i.e., net glucose uptake) was significantly suppressed following TBI (p<0.001). However, lactate fractional extraction, an index of cerebral lactate uptake related to systemic lactate supply, approximated 11% in both healthy control subjects and TBI patients. Further, neither the CMR for lactate (CMRlac, i.e., net lactate release), nor the tracer-measured cerebral lactate uptake differed between healthy controls and TBI patients. The percentages of lactate tracer taken up and released as (13)CO2 into the JB accounted for 92% and 91% for control and TBI conditions, respectively, suggesting that most cerebral lactate uptake was oxidized following TBI. Comparisons of isotopic enrichments of lactate oxidation from infused [3-(13)C]lactate tracer and (13)C-glucose produced during hepatic and renal gluconeogenesis (GNG) showed that 75-80% of (13)CO2 released into the JB was from lactate and that the remainder was from the oxidation of glucose secondarily labeled from lactate. Hence, either directly as lactate uptake, or indirectly via GNG, peripheral lactate production accounted for ∼70% of carbohydrate (direct lactate uptake+uptake of glucose from lactate) consumed by the injured brain. Undiminished cerebral lactate fractional extraction and uptake suggest that arterial lactate supplementation may be used to compensate for decreased CMRgluc following TBI.
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Affiliation(s)
- Thomas C. Glenn
- UCLA Cerebral Blood Flow Laboratory, Los Angeles, California
- Department of Neurosurgery, UCLA Center for Health Sciences, Los Angeles, California
| | - Neil A. Martin
- UCLA Cerebral Blood Flow Laboratory, Los Angeles, California
- Department of Neurosurgery, UCLA Center for Health Sciences, Los Angeles, California
| | - Michael A. Horning
- Department of Integrative Biology, University of California, Berkeley, California
| | | | - David A. Hovda
- UCLA Cerebral Blood Flow Laboratory, Los Angeles, California
| | - Paul Vespa
- UCLA Cerebral Blood Flow Laboratory, Los Angeles, California
| | - George A. Brooks
- Department of Integrative Biology, University of California, Berkeley, California
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15
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Lottes RG, Newton DA, Spyropoulos DD, Baatz JE. Lactate as substrate for mitochondrial respiration in alveolar epithelial type II cells. Am J Physiol Lung Cell Mol Physiol 2015; 308:L953-61. [PMID: 25747963 DOI: 10.1152/ajplung.00335.2014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 03/03/2015] [Indexed: 12/29/2022] Open
Abstract
Because of the many energy-demanding functions they perform and their physical location in the lung, alveolar epithelial type II (ATII) cells have a rapid cellular metabolism and the potential to influence substrate availability and bioenergetics both locally in the lung and throughout the body. A thorough understanding of ATII cell metabolic function in the healthy lung is necessary for determining how metabolic changes may contribute to pulmonary disease pathogenesis; however, lung metabolism is poorly understood at the cellular level. Here, we examine lactate utilization by primary ATII cells and the ATII model cell line, MLE-15, and link lactate consumption directly to mitochondrial ATP generation. ATII cells cultured in lactate undergo mitochondrial respiration at near-maximal levels, two times the rates of those grown in glucose, and oxygen consumption under these conditions is directly linked to mitochondrial ATP generation. When both lactate and glucose are available as metabolic substrate, the presence of lactate alters glucose metabolism in ATII to favor reduced glycolytic function in a dose-dependent manner, suggesting that lactate is used in addition to glucose when both substrates are available. Lactate use by ATII mitochondria is dependent on monocarboxylate transporter (MCT)-mediated import, and ATII cells express MCT1, the isoform that mediates lactate import by cells in other lactate-consuming tissues. The balance of lactate production and consumption may play an important role in the maintenance of healthy lung homeostasis, whereas disruption of lactate consumption by factors that impair mitochondrial metabolism, such as hypoxia, may contribute to lactic acid build-up in disease.
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Affiliation(s)
- Robyn G Lottes
- Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina; and
| | - Danforth A Newton
- Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina; and
| | - Demetri D Spyropoulos
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - John E Baatz
- Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina; and
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16
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Brooks GA, Martin NA. Cerebral metabolism following traumatic brain injury: new discoveries with implications for treatment. Front Neurosci 2015; 8:408. [PMID: 25709562 PMCID: PMC4321351 DOI: 10.3389/fnins.2014.00408] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 11/23/2014] [Indexed: 01/04/2023] Open
Abstract
Because it is the product of glycolysis and main substrate for mitochondrial respiration, lactate is the central metabolic intermediate in cerebral energy substrate delivery. Our recent studies on healthy controls and patients following traumatic brain injury (TBI) using [6,6-(2)H2]glucose and [3-(13)C]lactate, along with cerebral blood flow (CBF) and arterial-venous (jugular bulb) difference measurements for oxygen, metabolite levels, isotopic enrichments and (13)CO2 show a massive and previously unrecognized mobilization of lactate from corporeal (muscle, skin, and other) glycogen reserves in TBI patients who were studied 5.7 ± 2.2 days after injury at which time brain oxygen consumption and glucose uptake (CMRO2 and CMRgluc, respectively) were depressed. By tracking the incorporation of the (13)C from lactate tracer we found that gluconeogenesis (GNG) from lactate accounted for 67.1 ± 6.9%, of whole-body glucose appearance rate (Ra) in TBI, which was compared to 15.2 ± 2.8% (mean ± SD, respectively) in healthy, well-nourished controls. Standard of care treatment of TBI patients in state-of-the-art facilities by talented and dedicated heath care professionals reveals presence of a catabolic Body Energy State (BES). Results are interpreted to mean that additional nutritive support is required to fuel the body and brain following TBI. Use of a diagnostic to monitor BES to provide health care professionals with actionable data in providing nutritive formulations to fuel the body and brain and achieve exquisite glycemic control are discussed. In particular, the advantages of using inorganic and organic lactate salts, esters and other compounds are examined. To date, several investigations on brain-injured patients with intact hepatic and renal functions show that compared to dextrose + insulin treatment, exogenous lactate infusion results in normal glycemia.
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Affiliation(s)
- George A. Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, BerkeleyBerkeley, CA, USA
| | - Neil A. Martin
- Department of Neurosurgery, David Geffen School of Medicine, University of California, Los AngelesLos Angeles, CA, USA
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17
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Abstract
We propose that the well-documented therapeutic actions of repeated physical activities over human lifespan are mediated by the rapidly turning over proto-oncogenic Myc (myelocytomatosis) network of transcription factors. This transcription factor network is unique in utilizing promoter and epigenomic (acetylation/deacetylation, methylation/demethylation) mechanisms for controlling genes that include those encoding intermediary metabolism (the primary source of acetyl groups), mitochondrial functions and biogenesis, and coupling their expression with regulation of cell growth and proliferation. We further propose that remote functioning of the network occurs because there are two arms of this network, which consists of driver cells (e.g., working myocytes) that metabolize carbohydrates, fats, proteins, and oxygen and produce redox-modulating metabolites such as H₂O₂, NAD⁺, and lactate. The exercise-induced products represent autocrine, paracrine, or endocrine signals for target recipient cells (e.g., aortic endothelium, hepatocytes, and pancreatic β-cells) in which the metabolic signals are coupled with genomic networks and interorgan signaling is activated. And finally, we propose that lactate, the major metabolite released from working muscles and transported into recipient cells, links the two arms of the signaling pathway. Recently discovered contributions of the Myc network in stem cell development and maintenance further suggest that regular physical activity may prevent age-related diseases such as cardiovascular pathologies, cancers, diabetes, and neurological functions through prevention of stem cell dysfunctions and depletion with aging. Hence, regular physical activities may attenuate the various deleterious effects of the Myc network on health, the wild side of the Myc-network, through modulating transcription of genes associated with glucose and energy metabolism and maintain a healthy human status.
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Affiliation(s)
- Kishorchandra Gohil
- Exercise Physiology Laboratory, Dept. of Integrative Biology, University of California, Berkeley, CA 94720, USA
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18
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Valenza F, Rosso L, Coppola S, Froio S, Colombo J, Dossi R, Fumagalli J, Salice V, Pizzocri M, Conte G, Gatti S, Santambrogio L, Gattinoni L. β-Adrenergic agonist infusion during extracorporeal lung perfusion: Effects on glucose concentration in the perfusion fluid and on lung function. J Heart Lung Transplant 2012; 31:524-30. [DOI: 10.1016/j.healun.2012.02.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/16/2011] [Accepted: 02/02/2012] [Indexed: 11/25/2022] Open
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19
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Johnson ML, Emhoff CAW, Horning MA, Brooks GA. Transpulmonary lactate shuttle. Am J Physiol Regul Integr Comp Physiol 2011; 302:R143-9. [PMID: 22031785 DOI: 10.1152/ajpregu.00402.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The shuttling of intermediary metabolites such as lactate through the vasculature contributes to the dynamic energy and biosynthetic needs of tissues. Tracer kinetic studies offer a powerful tool to measure the metabolism of substrates like lactate that are simultaneously taken up from and released into the circulation by organs, but in each circulatory passage, the entire cardiac output traverses the pulmonary parenchyma. To determine whether transpulmonary lactate shuttling affects whole-body lactate kinetics in vivo, we examined the effects of a lactate load (via lactate clamp, LC) and epinephrine (Epi) stimulation on transpulmonary lactate kinetics in an anesthetized rat model using a primed-continuous infusion of [U-(13)C]lactate. Under all conditions studied, control 1.2 (SD 0.7) (Con), LC 1.9 (SD 2.5), and Epi 1.9 (SD 3.5) mg/min net transpulmonary lactate uptake occurred. Compared with Con, a lactate load via LC significantly increased mixed central venous ([v]) [1.9 mM (SD 0.5) vs. 4.7 (SD 0.4)] and arterial ([a]) [1.6 mM (SD 0.4) vs. 4.1 (SD 0.6)] lactate concentrations (P < 0.05). Transpulmonary lactate gradient ([v] - [a]) was highest during the lactate clamp condition [0.6 mM (SD 0.7)] and lowest during Epi [0.2 mM (SD 0.5)] stimulation (P < 0.05). Tracer measured lactate fractional extractions were similar for control, 16.6% (SD 15.3), and lactate clamp, 8.2% (SD 15.3) conditions, but negative during Epi stimulation, -25.3% (SD 45.5) when there occurred a transpulmonary production, the conversion of mixed central venous pyruvate to arterial lactate. Further, isotopic equilibration between L and P occurred following tracer lactate infusion, but depending on compartment (v or a) and physiological stimulus, [L]/[P] concentration and isotopic enrichment ratios ranged widely. We conclude that pulmonary arterial-vein concentration difference measurements across the lungs provide an incomplete, and perhaps misleading picture of parenchymal lactate metabolism, especially during epinephrine stimulation.
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Affiliation(s)
- Matthew L Johnson
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, 94720-3140, USA
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