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Brueggeman JM, Zhao J, Schank M, Yao ZQ, Moorman JP. Trained Immunity: An Overview and the Impact on COVID-19. Front Immunol 2022; 13:837524. [PMID: 35251030 PMCID: PMC8891531 DOI: 10.3389/fimmu.2022.837524] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/28/2022] [Indexed: 01/13/2023] Open
Abstract
Effectively treating infectious diseases often requires a multi-step approach to target different components involved in disease pathogenesis. Similarly, the COVID-19 pandemic has become a global health crisis that requires a comprehensive understanding of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) infection to develop effective therapeutics. One potential strategy to instill greater immune protection against COVID-19 is boosting the innate immune system. This boosting, termed trained immunity, employs immune system modulators to train innate immune cells to produce an enhanced, non-specific immune response upon reactivation following exposure to pathogens, a process that has been studied in the context of in vitro and in vivo clinical studies prior to the COVID-19 pandemic. Evaluation of the underlying pathways that are essential to inducing protective trained immunity will provide insight into identifying potential therapeutic targets that may alleviate the COVID-19 crisis. Here we review multiple immune training agents, including Bacillus Calmette-Guérin (BCG), β-glucan, and lipopolysaccharide (LPS), and the two most popular cell types involved in trained immunity, monocytes and natural killer (NK) cells, and compare the signaling pathways involved in innate immunity. Additionally, we discuss COVID-19 trained immunity clinical trials, emphasizing the potential of trained immunity to fight SARS-CoV-2 infection. Understanding the mechanisms by which training agents activate innate immune cells to reprogram immune responses may prove beneficial in developing preventive and therapeutic targets against COVID-19.
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Affiliation(s)
- Justin M. Brueggeman
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States,Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University (ETSU), Johnson City, TN, United States,Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, United States
| | - Juan Zhao
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States,Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University (ETSU), Johnson City, TN, United States
| | - Madison Schank
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States,Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University (ETSU), Johnson City, TN, United States
| | - Zhi Q. Yao
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States,Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University (ETSU), Johnson City, TN, United States,Hepatitis (HCV/HBV/HIV) Program, James H. Quillen VA Medical Center, Department of Veterans Affairs, Johnson City, TN, United States
| | - Jonathan P. Moorman
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States,Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, East Tennessee State University (ETSU), Johnson City, TN, United States,Hepatitis (HCV/HBV/HIV) Program, James H. Quillen VA Medical Center, Department of Veterans Affairs, Johnson City, TN, United States,*Correspondence: Jonathan P. Moorman,
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Ramendra R, Mancini M, Ayala JM, Tung LT, Isnard S, Lin J, Routy JP, Nijnik A, Langlais D. Glutathione Metabolism Is a Regulator of the Acute Inflammatory Response of Monocytes to (1→3)-β-D-Glucan. Front Immunol 2021; 12:694152. [PMID: 34858388 PMCID: PMC8631827 DOI: 10.3389/fimmu.2021.694152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 10/26/2021] [Indexed: 12/13/2022] Open
Abstract
(1→3)-β-D-Glucan (BDG) represents a potent pathogen-associated molecular pattern (PAMP) in triggering the host response to fungal and some bacterial infections. Monocytes play a key role in recognizing BDG and governing the acute host response to infections. However, the mechanisms regulating monocyte's acute response to BDG are poorly understood. We sought to investigate the response of monocytes to BDG at the epigenetic, transcriptomic, and molecular levels. Response of human monocytes to 1, 4, and 24 hours of BDG exposure was investigated using RNA-seq, ATAC-seq, H3K27ac and H3K4me1 ChIP-seq. We show that pathways including glutathione metabolism, pentose phosphate pathway, and citric acid cycle were upregulated at the epigenetic and transcriptomic levels in response to BDG exposure. Strikingly, unlike bacterial lipopolysaccharides, BDG induced intracellular glutathione synthesis. BDG exposure also induced NADP synthesis, increased NADPH/NADP ratio, and increased expression of genes involved in the pentose phosphate pathway in a GSH-dependent manner. By inhibiting GSH synthesis with L-buthionine sulfoximine (BSO) before BDG exposure we show that the GSH pathway promotes cell survival and regulates monocyte's effector functions including NO production, phagocytosis, and cytokine production. In summary, our work demonstrates that BDG induces glutathione synthesis and metabolism in monocytes, which is a major promoter of the acute functional response of monocytes to infections.
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Affiliation(s)
- Rayoun Ramendra
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
- McGill University Research Centre on Complex Traits, Montreal, QC, Canada
- McGill University Genome Centre, Montreal, QC, Canada
| | - Mathieu Mancini
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
- McGill University Research Centre on Complex Traits, Montreal, QC, Canada
- McGill University Genome Centre, Montreal, QC, Canada
| | - Jose-Mauricio Ayala
- McGill University Research Centre on Complex Traits, Montreal, QC, Canada
- McGill University Genome Centre, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Lin Tze Tung
- McGill University Research Centre on Complex Traits, Montreal, QC, Canada
- Department of Physiology, McGill University, Montreal, QC, Canada
| | - Stephane Isnard
- Chronic Viral Illness Service, McGill University Health Centre, Montreal, QC, Canada
| | - John Lin
- Chronic Viral Illness Service, McGill University Health Centre, Montreal, QC, Canada
| | - Jean-Pierre Routy
- Chronic Viral Illness Service, McGill University Health Centre, Montreal, QC, Canada
| | - Anastasia Nijnik
- McGill University Research Centre on Complex Traits, Montreal, QC, Canada
- Department of Physiology, McGill University, Montreal, QC, Canada
| | - David Langlais
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
- McGill University Research Centre on Complex Traits, Montreal, QC, Canada
- McGill University Genome Centre, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
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