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Shippy DC, Evered AH, Ulland TK. Ketone body metabolism and the NLRP3 inflammasome in Alzheimer's disease. Immunol Rev 2024. [PMID: 38989642 DOI: 10.1111/imr.13365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Alzheimer's disease (AD) is a degenerative brain disorder and the most common form of dementia. AD pathology is characterized by senile plaques and neurofibrillary tangles (NFTs) composed of amyloid-β (Aβ) and hyperphosphorylated tau, respectively. Neuroinflammation has been shown to drive Aβ and tau pathology, with evidence suggesting the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome as a key pathway in AD pathogenesis. NLRP3 inflammasome activation in microglia, the primary immune effector cells of the brain, results in caspase-1 activation and secretion of IL-1β and IL-18. Recent studies have demonstrated a dramatic interplay between the metabolic state and effector functions of immune cells. Microglial metabolism in AD is of particular interest, as ketone bodies (acetone, acetoacetate (AcAc), and β-hydroxybutyrate (BHB)) serve as an alternative energy source when glucose utilization is compromised in the brain of patients with AD. Furthermore, reduced cerebral glucose metabolism concomitant with increased BHB levels has been demonstrated to inhibit NLRP3 inflammasome activation. Here, we review the role of the NLRP3 inflammasome and microglial ketone body metabolism in AD pathogenesis. We also highlight NLRP3 inflammasome inhibition by several ketone body therapies as a promising new treatment strategy for AD.
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Affiliation(s)
- Daniel C Shippy
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA
| | - Abigail H Evered
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA
- Cellular and Molecular Pathology Graduate Program, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA
| | - Tyler K Ulland
- Department of Pathology and Laboratory Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA
- Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA
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Jang J, Kim SR, Lee JE, Lee S, Son HJ, Choe W, Yoon KS, Kim SS, Yeo EJ, Kang I. Molecular Mechanisms of Neuroprotection by Ketone Bodies and Ketogenic Diet in Cerebral Ischemia and Neurodegenerative Diseases. Int J Mol Sci 2023; 25:124. [PMID: 38203294 PMCID: PMC10779133 DOI: 10.3390/ijms25010124] [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: 11/20/2023] [Revised: 12/18/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024] Open
Abstract
Ketone bodies (KBs), such as acetoacetate and β-hydroxybutyrate, serve as crucial alternative energy sources during glucose deficiency. KBs, generated through ketogenesis in the liver, are metabolized into acetyl-CoA in extrahepatic tissues, entering the tricarboxylic acid cycle and electron transport chain for ATP production. Reduced glucose metabolism and mitochondrial dysfunction correlate with increased neuronal death and brain damage during cerebral ischemia and neurodegeneration. Both KBs and the ketogenic diet (KD) demonstrate neuroprotective effects by orchestrating various cellular processes through metabolic and signaling functions. They enhance mitochondrial function, mitigate oxidative stress and apoptosis, and regulate epigenetic and post-translational modifications of histones and non-histone proteins. Additionally, KBs and KD contribute to reducing neuroinflammation and modulating autophagy, neurotransmission systems, and gut microbiome. This review aims to explore the current understanding of the molecular mechanisms underpinning the neuroprotective effects of KBs and KD against brain damage in cerebral ischemia and neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Jiwon Jang
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Su Rim Kim
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Jo Eun Lee
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Seoyeon Lee
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Hyeong Jig Son
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Wonchae Choe
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
- Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Kyung-Sik Yoon
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
- Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Sung Soo Kim
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
- Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Eui-Ju Yeo
- Department of Biochemistry, College of Medicine, Gachon University, Incheon 21999, Republic of Korea
| | - Insug Kang
- Department of Biomedical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; (J.J.); (S.R.K.); (J.E.L.); (S.L.); (H.J.S.); (W.C.); (K.-S.Y.); (S.S.K.)
- Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea
- Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
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Nomura M, Murad NF, Madhavan SS, Eap B, Garcia TY, Aguirre CG, Verdin E, Ellerby L, Furman D, Newman JC. A ketogenic diet reduces age-induced chronic neuroinflammation in mice Running title: ketogenic diet and brain inflammaging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.01.569598. [PMID: 38106160 PMCID: PMC10723274 DOI: 10.1101/2023.12.01.569598] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Beta-hydroxybutyrate (BHB) is a ketone body synthesized during fasting or strenuous exercise. Our previous study demonstrated that a cyclic ketogenic diet (KD), which induces BHB levels similar to fasting every other week, reduces midlife mortality and improves memory in aging mice. BHB actively regulates gene expression and inflammatory activation through non-energetic signaling pathways. Neither of these activities has been well-characterized in the brain and they may represent mechanisms by which BHB affects brain function during aging. First, we analyzed hepatic gene expression in an aging KD-treated mouse cohort using bulk RNA-seq. In addition to the downregulation of TOR pathway activity, cyclic KD reduces inflammatory gene expression in the liver. We observed via flow cytometry that KD also modulates age-related systemic T cell functions. Next, we investigated whether BHB affects brain cells transcriptionally in vitro. Gene expression analysis in primary human brain cells (microglia, astrocytes, neurons) using RNA-seq shows that BHB causes a mild level of inflammation in all three cell types. However, BHB inhibits the more pronounced LPS-induced inflammatory gene activation in microglia. Furthermore, we confirmed that BHB similarly reduces LPS-induced inflammation in primary mouse microglia and bone marrow-derived macrophages (BMDMs). BHB is recognized as an inhibitor of histone deacetylase (HDAC), an inhibitor of NLRP3 inflammasome, and an agonist of the GPCR Hcar2. Nevertheless, in microglia, BHB's anti-inflammatory effects are independent of these known mechanisms. Finally, we examined the brain gene expression of 12-month-old male mice fed with one-week and one-year cyclic KD. While a one-week KD increases inflammatory signaling, a one-year cyclic KD reduces neuroinflammation induced by aging. In summary, our findings demonstrate that BHB mitigates the microglial response to inflammatory stimuli, like LPS, possibly leading to decreased chronic inflammation in the brain after long-term KD treatment in aging mice.
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Affiliation(s)
| | | | - Sidharth S Madhavan
- Buck Institute for Research on Aging, Novato, CA, USA
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Brenda Eap
- Buck Institute for Research on Aging, Novato, CA, USA
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | | | - Carlos Galicia Aguirre
- Buck Institute for Research on Aging, Novato, CA, USA
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Eric Verdin
- Buck Institute for Research on Aging, Novato, CA, USA
| | - Lisa Ellerby
- Buck Institute for Research on Aging, Novato, CA, USA
| | - David Furman
- Buck Institute for Research on Aging, Novato, CA, USA
| | - John C Newman
- Buck Institute for Research on Aging, Novato, CA, USA
- Division of Geriatrics, University of California, San Francisco, San Francisco, CA, USA
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