Species-specific metabolic reprogramming in human and mouse microglia during inflammatory pathway induction

Article https://doi.org/10.1038/s41467-023-42096-7 Species-specific metabolic reprogramming in human and mouse microglia during inflammatory pathway induction Received: 28 January 2023 Check for updates 1234567890():,; 1234567890():,; Accepted: 22 September 2023 Angélica María Sabogal-Guáqueta1,8, Alejandro Marmolejo-Garza1,2,8, Marina Trombetta-Lima1,2, Asmaa Oun 1, Jasmijn Hunneman1, Tingting Chen1, Jari Koistinaho3,4, Sarka Lehtonen 3, Arjan Kortholt 5,6, Justina C. Wolters 7, Barbara M. Bakker 7, Bart J. L. Eggen 2, Erik Boddeke 2 & Amalia Dolga 1 Metabolic reprogramming is a hallmark of the immune cells in response to inflammatory stimuli. This metabolic process involves a switch from oxidative phosphorylation (OXPHOS) to glycolysis or alterations in other metabolic pathways. However, most of the experimental findings have been acquired in murine immune cells, and little is known about the metabolic reprogramming of human microglia. In this study, we investigate the transcriptomic, proteomic, and metabolic profiles of mouse and iPSC-derived human microglia challenged with the TLR4 agonist LPS. We demonstrate that both species display a metabolic shift and an overall increased glycolytic gene signature in response to LPS treatment. The metabolic reprogramming is characterized by the upregulation of hexokinases in mouse microglia and phosphofructokinases in human microglia. This study provides a direct comparison of metabolism between mouse and human microglia, highlighting the speciesspecific pathways involved in immunometabolism and the importance of considering these differences in translational research. Microglia are the resident innate immune cells of the central nervous system (CNS) and are involved in the immune response to pathogens or alteration to the CNS microenvironment. Microglia are also required for neurodevelopment, neuroplasticity, and tissue repair1–3. Dysregulation of microglial function has been well established in pathologies linked to neurodegeneration, including Alzheimer’s disease (AD)4–6, Parkinson’s disease7, multiple sclerosis,8,9 and Huntington’s disease10. The lack of disease-modifying therapies for these conditions demonstrates the need to better delineate mechanisms that govern microglial function and to study the modulation of key mediators of such mechanisms for potential therapies. Microglia acquire an inflammatory phenotype comprising production of pro-inflammatory cytokines, such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in response to pathogenic stimuli. Besides the inflammatory phenotype, microglia can adopt several phenotypes to clear pathogenic substances, eliminate cellular/synaptic debris, clear metabolic waste, regulate synaptic pruning, neuronal maturation, and support neuro-regeneration. During 1 Department of Molecular Pharmacology, Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Behavioral and Cognitive Neurosciences (BCN), University of Groningen, Groningen, The Netherlands. 2Department of Biomedical Sciences of Cells & Systems, section Molecular Neurobiology, Faculty of Medical Sciences, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. 3A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland. 4Neuroscience Center, Helsinki Institute for Life Science, University of Helsinki, Haartmaninkatu 8, 00290 Helsinki, Finland. 5Department of Cell Biochemistry, University of Groningen, Groningen, The Netherlands. 6YETEMInnovative Technologies Application and Research Centre Suleyman Demirel University, Isparta, Turkey. 7Laboratory of Pediatrics, Section Systems Medicine of Metabolism and Signaling, Faculty of Medical Sciences, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. 8 These authors contributed equally: Angélica María Sabogal-Guáqueta, Alejandro Marmolejo-Garza. e-mail: Nature Communications | (2023)14:6454 1 Article phenotypic transition, metabolic reprogramming is considered a hallmark of inflammatory murine macrophages/microglia11,12. Metabolic reprogramming or a metabolic switch encompasses a variety of cellular alterations in bioenergetic pathways to adapt to the cellular metabolic needs. The changes in metabolic pathways include several processes, such as oxidative phosphorylation (OXPHOS), tricyclic acid cycle (TCA cycle), glycolysis, the pentose phosphate pathway, amino acid metabolism, and fatty acid oxidation. Recent studies have shown that mouse primary microglia are able to switch their cell metabolism from mainly mitochondrial OXPHOS to glycolysis12 in response to pro-inflammatory stimuli, such as lipopolysaccharides (LPS), and Amyloid-β (Aβ)13 in acute and chronic manners, pointing at a role of metabolism in trained innate immunity in microglia. Similarly, this phenomenon of metabolic switch to glycolysis is also present in mouse macrophages, dendritic cells, NK cells, B cells and effector T cells14,15. Under physiological conditions, immune cells, including microglia and macrophages, primarily rely on oxidative phosphorylation16. Under inflammatory conditions, an accumulation of citrate and succinate has been reported in macrophages, which contributes to an increase in reactive oxygen species (ROS) and nitric oxide production, leading to a switch from anti- to pro-inflammatory phenotype in the immune cells14,17. These findings were followed by an exponential surge of interest in reprogramming metabolic pathways and the term of “immunometabolism” was coined in 2011 by Mathis & Schoelson18. However, the vast majority of these experimental studies have been performed in murine immune cells and not much information is available on metabolic reprogramming in human immune cells, specifically innate brain immune cells, microglia. For instance, speciesspecific differences in LPS-treated macrophages have been reported in mouse and human systems11 indicating that murine findings shall be interpreted with caution and highlighting the need to establish more adequate human model systems. Studies of human brain microglia have been performed on isolated microglia from fresh post-mortem samples from potentially neuropathologically affected individuals, which might be hindered by a high interindividual variation. Alternatively, robust differentiation protocols of iPSC-derived human microglia could provide a possibility to study metabolic profiles. First studies on iPSC-derived microglia were documented in 2016 and mainly focused on the characterization of the microglial phenotype in terms of differentiation and maturation. Hence, the goal of our study was to investigate the metabolic reprogramming in human iPSC-derived microglia compared with mouse microglial in vitro and in vivo models in response to the prototypical stimulus LPS. In this study, we show dysregulation of metabolic pathways concomitant with upregulation of inflammatory (...truncated)