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Jin M, Fang J, Wang JJ, Shao X, Xu SW, Liu PQ, Ye WC, Liu ZP. Regulation of toll-like receptor (TLR) signaling pathways in atherosclerosis: from mechanisms to targeted therapeutics. Acta Pharmacol Sin 2023; 44:2358-2375. [PMID: 37550526 PMCID: PMC10692204 DOI: 10.1038/s41401-023-01123-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 06/04/2023] [Indexed: 08/09/2023] Open
Abstract
Atherosclerosis, one of the life-threatening cardiovascular diseases (CVDs), has been demonstrated to be a chronic inflammatory disease, and inflammatory and immune processes are involved in the origin and development of the disease. Toll-like receptors (TLRs), a class of pattern recognition receptors that trigger innate immune responses by identifying pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), regulate numerous acute and chronic inflammatory diseases. Recent studies reveal that TLRs have a vital role in the occurrence and development of atherosclerosis, including the initiation of endothelial dysfunction, interaction of various immune cells, and activation of a number of other inflammatory pathways. We herein summarize some other inflammatory signaling pathways, protein molecules, and cellular responses associated with TLRs, such as NLRP3, Nrf2, PCSK9, autophagy, pyroptosis and necroptosis, which are also involved in the development of AS. Targeting TLRs and their regulated inflammatory events could be a promising new strategy for the treatment of atherosclerotic CVDs. Novel drugs that exert therapeutic effects on AS through TLRs and their related pathways are increasingly being developed. In this article, we comprehensively review the current knowledge of TLR signaling pathways in atherosclerosis and actively seek potential therapeutic strategies using TLRs as a breakthrough point in the prevention and therapy of atherosclerosis.
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Affiliation(s)
- Mei Jin
- Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, 511436, China
| | - Jian Fang
- Affiliated Huadu Hospital, Southern Medical University (People's Hospital of Huadu District), Guangzhou, 510800, China
| | - Jiao-Jiao Wang
- Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, 511436, China
| | - Xin Shao
- Department of Food Science and Engineering, Jinan University, Guangzhou, 511436, China
| | - Suo-Wen Xu
- Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Pei-Qing Liu
- Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, 511436, China.
- National-Local Joint Engineering Lab of Druggability and New Drugs Evaluation, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, 510006, China.
| | - Wen-Cai Ye
- Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, 511436, China.
| | - Zhi-Ping Liu
- Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, 511436, China.
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Choi T, Maiti G, Chakravarti S. Three-Dimensional Modeling of CpG DNA Binding with Matrix Lumican Shows Leucine-Rich Repeat Motif Involvement as in TLR9-CpG DNA Interactions. Int J Mol Sci 2023; 24:14990. [PMID: 37834438 PMCID: PMC10573802 DOI: 10.3390/ijms241914990] [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: 08/22/2023] [Revised: 09/26/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
Lumican is an extracellular matrix proteoglycan known to regulate toll-like receptor (TLR) signaling in innate immune cells. In experimental settings, lumican suppresses TLR9 signaling by binding to and sequestering its synthetic ligand, CpG-DNA, in non-signal permissive endosomes. However, the molecular details of lumican interactions with CpG-DNA are obscure. Here, the 3-D structure of the 22 base-long CpG-DNA (CpG ODN_2395) bound to lumican or TLR9 were modeled using homology modeling and docking methods. Some of the TLR9-CpG ODN_2395 features predicted by our model are consistent with the previously reported TLR9-CpG DNA crystal structure, substantiating our current analysis. Our modeling indicated a smaller buried surface area for lumican-CpG ODN_2395 (1803 Å2) compared to that of TLR9-CpG ODN_2395 (2094 Å2), implying a potentially lower binding strength for lumican and CpG-DNA than TLR9 and CpG-DNA. The docking analysis identified 32 amino acids in lumican LRR1-11 interacting with CpG ODN_2395, primarily through hydrogen bonding, salt-bridges, and hydrophobic interactions. Our study provides molecular insights into lumican and CpG-DNA interactions that may lead to molecular targets for modulating TLR9-mediated inflammation and autoimmunity.
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Affiliation(s)
- Tansol Choi
- Department of Ophthalmology, NYU Grossman School of Medicine, New York, NY 10016, USA;
| | - George Maiti
- Department of Ophthalmology, NYU Grossman School of Medicine, New York, NY 10016, USA;
| | - Shukti Chakravarti
- Department of Ophthalmology, NYU Grossman School of Medicine, New York, NY 10016, USA;
- Department of Pathology, NYU Grossman School of Medicine, New York, NY 10016, USA
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3
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Choi T, Maiti G, Chakravarti S. 3D modeling of CpG DNA binding with matrix lumican shows leucine-rich repeat motif involvement as in TLR9-CpG DNA interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.21.554201. [PMID: 37662233 PMCID: PMC10473624 DOI: 10.1101/2023.08.21.554201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Lumican is an extracellular matrix proteoglycan, known to regulate toll-like receptor (TLR) signaling in innate immune cells. In experimental settings, lumican suppresses TLR9 signaling by binding to, and sequestering its synthetic ligand, CpG-DNA, in non-signal permissive endosomes. However, the molecular details of lumican interactions with CpG-DNA are obscure. Here, the 3-D structure of the 22 base-long CpG-DNA (CpG ODN_2395) bound to lumican or TLR9 were modeled using homology modeling and docking methods. Some of the TLR9-CpG ODN_2395 features predicted by our model are consistent with the previously reported TLR9-CpG DNA crystal structure, substantiating our current analysis. Our modeling indicated a smaller buried surface area for lumican-CpG ODN_2395 (1803 Å2) compared to that of TLR9-CpG ODN_2395 (2094 Å2), implying a potentially lower binding strength for lumican and CpG-DNA than TLR9 and CpG-DNA. The docking analysis identified 32 amino acids in lumican LRR1-11 interacting with CpG ODN_2395, primarily through hydrogen bonding, salt-bridges and hydrophobic interactions. Our study provides molecular insights into lumican and CpG-DNA interactions that may lead to molecular targets for modulating TLR9 mediated inflammation and autoimmunity.
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Affiliation(s)
- Tansol Choi
- Department of Ophthalmology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - George Maiti
- Department of Ophthalmology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Shukti Chakravarti
- Department of Ophthalmology, NYU Grossman School of Medicine, New York, NY 10016, USA
- Department of Pathology, NYU Grossman School of Medicine, New York, NY 10016, USA
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4
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Huo C, Tian H, Rao H, Zeng B, Li D, Li Z, Li Y. Genetic diversity of Toll-like receptor 9 in swamp eels (Monopterus albus). JOURNAL OF FISH BIOLOGY 2023; 102:1149-1156. [PMID: 36879356 DOI: 10.1111/jfb.15366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Accepted: 02/28/2023] [Indexed: 05/13/2023]
Abstract
The swamp eel, Monopterus albus, is an important aquaculture species in Asia (mainly China) whose production has seriously suffered from infectious diseases. In spite of the critical requirement for aquaculture practices, to date there is scant information on its immune defence. Here, the genetic characteristics of Toll-like receptor 9 (TLR9), which plays crucial roles in the initiation of host defence against microbial invasion, were analysed. It exhibits a striking lack of genetic variation resulting from a recent demographic bottleneck. A comparison with the homologue of M. javanensis revealed that replacement but not silent differences have nonrandomly accumulated in the coding sequences at the early stage following their split from a common ancestor. Furthermore, the replacements relevant to the type II functional divergence have mainly occurred in structural motifs mediating ligand recognition and receptor homodimerization. These results provide hints to understand the diversity-based strategy of TLR9 in the arms race against pathogens. Furthermore, the findings reported here give credence to the importance of basic immunology knowledge, especially for the key elements, in genetic engineering and breeding for disease resistance in the eel and other fishes.
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Affiliation(s)
- Caifei Huo
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, People's Republic of China
| | - Haifeng Tian
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, People's Republic of China
| | - Han Rao
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, People's Republic of China
| | - Bo Zeng
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, People's Republic of China
- Key Laboratory of Livestock and Poultry Multi-omics, Ministry of Agriculture and Rural Affairs, Sichuan Agricultural University, Chengdu, People's Republic of China
- Institute of Animal Genetics and Breeding, Sichuan Agricultural University, Chengdu, People's Republic of China
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, People's Republic of China
| | - Debing Li
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, People's Republic of China
| | - Zhong Li
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, People's Republic of China
| | - Yan Li
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, People's Republic of China
- Key Laboratory of Livestock and Poultry Multi-omics, Ministry of Agriculture and Rural Affairs, Sichuan Agricultural University, Chengdu, People's Republic of China
- Institute of Animal Genetics and Breeding, Sichuan Agricultural University, Chengdu, People's Republic of China
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, People's Republic of China
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5
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Exploring the Interaction between 3-D Structure of TLR 9 and Prostaglandin Analogues. ARAB J CHEM 2023. [DOI: 10.1016/j.arabjc.2023.104692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
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Tu ATT, Hoshi K, Shobo M, Yamazaki T. G-quadruplex-based CpG oligodeoxynucleotide/DOTAP complex strongly stimulates immunity in CpG motif-specific and loop-length-dependent manners. NANOMEDICINE : NANOTECHNOLOGY, BIOLOGY, AND MEDICINE 2022; 40:102508. [PMID: 34906721 DOI: 10.1016/j.nano.2021.102508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/11/2021] [Accepted: 11/19/2021] [Indexed: 06/14/2023]
Abstract
Guanine-quadruplex (G4) oligodeoxynucleotides (ODNs) that contain unmethylated cytosine-phosphate-guanine motifs (G4 CpG ODN) with phosphodiester backbones are safer than the phosphorothioate (PT)-modified CpG ODNs recently used as vaccine adjuvants. However, cellular uptake and the nuclease stability of G4 CpG ODNs are still insufficient, resulting in lower immunostimulatory activity than PT-modified CpG ODNs. We aimed to enhance the immunostimulatory properties of G4 CpG ODNs by complexing with the cationic liposome 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). The complex acquired nuclease resistance and improved cellular uptake. The immunostimulatory activity of the G4 CpG ODN-DOTAP lipoplexes was enhanced to a level comparable to that of PT-modified ODNs. In addition, the lipoplexes based on unmodified G4 CpG ODNs demonstrated CpG motif-specific immunostimulant activity, although PT-modified ODNs lacking the CpG motif could activate human immune cells. Interestingly, G4 CpG ODN-DOTAP lipoplexes induced interferon-α production in a loop-length dependent manner.
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Affiliation(s)
- Anh Thi Tram Tu
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan; Division of Life Science, Hokkaido university, Sapporo, Japan
| | - Kazuaki Hoshi
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Miwako Shobo
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Tomohiko Yamazaki
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan; Division of Life Science, Hokkaido university, Sapporo, Japan.
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Koutsogiannaki S, Bu W, Hou L, Shibamura-Fujiogi M, Ishida H, Ohto U, Eckenhoff RG, Yuki K. The effect of anesthetics on toll like receptor 9. FASEB J 2020; 34:14645-14654. [PMID: 32901993 DOI: 10.1096/fj.202000791rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 08/17/2020] [Accepted: 08/20/2020] [Indexed: 12/11/2022]
Abstract
Toll like receptors (TLRs) are critical receptors to respond to danger signals, and their functions are relevant in the perioperative period. We previously reported that volatile anesthetics directly bound to TLR2 and TLR4 and attenuated their functions. Given that TLR9 can respond to mitochondrial DNA, a danger signal that is released upon tissue injury, we examined the role of anesthetics on TLR9 function. Our reporter assay showed that volatile anesthetics isoflurane and sevoflurane increased the activation of TLR9, while propofol attenuated it. TLR9 activation occurs via its dimerization. The dimerization is facilitated by unmethylated cytosine-phosphate-guanine (CpG) DNA as well as DNA containing cytosine at the second position from 5'-end (5'-xCx DNA). Our structural analysis using photoactivable anesthetics and rigid docking simulation showed that isoflurane and sevoflurane bound to both TLR9 dimer interface and 5'-xCx DNA binding site. Propofol bound to the TLR9 antagonist binding site. This is the first illustration that anesthetics can affect the binding of nucleic acids to their receptor. This study sets the foundation for the effect of anesthetics on TLR9 and will pave the way for future studies to determine the significance of such interactions in the clinical setting.
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Affiliation(s)
- Sophia Koutsogiannaki
- Department of Anesthesiology, Critical Care and Pain Medicine, Cardiac Anesthesia Division, Boston Children's Hospital, Boston, MA, USA.,Department of Anaesthesia, Harvard Medical School, Boston, MA, USA.,Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Weiming Bu
- Department of Anesthesia and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Lifei Hou
- Department of Anesthesiology, Critical Care and Pain Medicine, Cardiac Anesthesia Division, Boston Children's Hospital, Boston, MA, USA.,Department of Anaesthesia, Harvard Medical School, Boston, MA, USA.,Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Miho Shibamura-Fujiogi
- Department of Anesthesiology, Critical Care and Pain Medicine, Cardiac Anesthesia Division, Boston Children's Hospital, Boston, MA, USA.,Department of Anaesthesia, Harvard Medical School, Boston, MA, USA.,Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Hanako Ishida
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Umeharu Ohto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Roderic G Eckenhoff
- Department of Anesthesia and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Koichi Yuki
- Department of Anesthesiology, Critical Care and Pain Medicine, Cardiac Anesthesia Division, Boston Children's Hospital, Boston, MA, USA.,Department of Anaesthesia, Harvard Medical School, Boston, MA, USA.,Department of Immunology, Harvard Medical School, Boston, MA, USA
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8
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Tu ATT, Hoshi K, Ikebukuro K, Hanagata N, Yamazaki T. Monomeric G-Quadruplex-Based CpG Oligodeoxynucleotides as Potent Toll-Like Receptor 9 Agonists. Biomacromolecules 2020; 21:3644-3657. [PMID: 32857497 DOI: 10.1021/acs.biomac.0c00679] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Synthetic oligodeoxynucleotides (ODNs) containing unmethylated cytosine-phosphate-guanine (CpG) motifs trigger the immune response by stimulating endosomal Toll-like receptor (TLR) 9. Natural linear ODNs are susceptible to nuclease degradation, thereby limiting their clinical applications. Here, we designed monomeric G-quadruplex-based CpG ODNs (G4 CpG ODNs) containing CpG motifs in the central loop region of the G4 structure. The monomeric G4 CpG ODNs were more stable in serum than the linear ODNs. The monomeric G4 CpG ODNs containing two or three CpG motifs induced the production of immunostimulatory cytokines interleukin (IL)-6, IL-12, and interferon (IFN)-β in mouse macrophage-like RAW264 cells. We also showed that the number of CpG motifs and the number of nucleotides between the CpG motif and G-tracts define the efficacy of the G4 CpG ODNs in activating TLR9. Incubating human peripheral blood mononuclear cells with G4 CpG ODNs promoted IL-6 and IFN-γ production, confirming their stimulatory effects on human immune cells. Mice given intraperitoneal injections of G4 CpG ODNs produced higher plasma IL-6 compared with injections of linear ODNs. These findings provide further understanding of the parameters governing the immunostimulatory activity of G4 CpG ODNs, thereby providing insights into the rational design of highly potent G4 CpG ODNs for vaccine adjuvants.
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Affiliation(s)
- Anh Thi Tram Tu
- Division of Life Science, Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0808, Japan.,Nanomedicine Group, Research Center for Functional Materials (RCFM), National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Kazuaki Hoshi
- Nanomedicine Group, Research Center for Functional Materials (RCFM), National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Kazunori Ikebukuro
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei 184-8588, Japan
| | - Nobutaka Hanagata
- Division of Life Science, Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0808, Japan.,Nanotechnology Innovation Station, National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Tomohiko Yamazaki
- Division of Life Science, Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0808, Japan.,Nanomedicine Group, Research Center for Functional Materials (RCFM), National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan
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Bartok E, Hartmann G. Immune Sensing Mechanisms that Discriminate Self from Altered Self and Foreign Nucleic Acids. Immunity 2020; 53:54-77. [PMID: 32668228 PMCID: PMC7359798 DOI: 10.1016/j.immuni.2020.06.014] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 12/19/2022]
Abstract
All lifeforms have developed highly sophisticated systems equipped to detect altered self and non-self nucleic acids (NA). In vertebrates, NA-sensing receptors safeguard the integrity of the organism by detecting pathogens, dyshomeostasis and damage, and inducing appropriate responses to eliminate pathogens and reconstitute homeostasis. Effector mechanisms include i) immune signaling, ii) restriction of NA functions such as inhibition of mRNA translation, and iii) cell death pathways. An appropriate effector response is necessary for host defense, but dysregulated NA-sensing can lead to devastating autoimmune and autoinflammatory disease. Their inherent biochemical similarity renders the reliable distinction between self NA under homeostatic conditions and altered or exogenous NA particularly challenging. In this review, we provide an overview of recent progress in our understanding of the closely coordinated and regulated network of innate immune receptors, restriction factors, and nucleases to effectively respond to pathogens and maintain host integrity.
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Affiliation(s)
- Eva Bartok
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Gunther Hartmann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany.
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Fehér K. Single Stranded DNA Immune Modulators with Unmethylated CpG Motifs: Structure and Molecular Recognition by Toll-Like Receptor 9. Curr Protein Pept Sci 2020; 20:1060-1068. [PMID: 31470785 DOI: 10.2174/1389203720666190830162149] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 03/13/2019] [Accepted: 04/12/2019] [Indexed: 01/04/2023]
Abstract
Single stranded microbial DNA fragments with unmethylated deoxycytidylyldeoxyguanosine dinucleotide (CpG) motifs are interpreted as danger signals by the innate immune system via recognition by the Toll-like Receptor 9 (TLR9). Their synthetic analogues, Oligodeoxynucleotides (ODN) comprise a promising class of immune modulators with potential applications in the treatment of multiple diseases, such as cancer, autoimmune diseases or allergy. ODN molecules contain a core hexamer sequence, which is species specific consisting of GACGTT and AACGT for mouse and GTCGTT in humans. Assessment of structural features of different type of ODNs is highly challenging. NMR spectroscopic insights were gained for a short, single CpG motif containing ODN 1668. The structural basis of ODN recognition by TLR9 recently started to unravel as crystal structures of TLR9 orthologues in complex with ODN 1668 were solved. Systematic investigations of ODN sequences revealed that ODNs with a single CpG motif are capable of activating mouse TLR9, but two closely positioned CpG motifs are necessary for activation of human TLR9. Furthermore, longer ODNs with TCC and TCG sequences at the 5' end were shown to activate TLR9 with higher efficiency. It was revealed that 5'-xCx motif containing short ODNs (sODN) are able to augment the immune response of short, single CpG containing ODNs, which are incapable of activating of TLR9 alone. All these observations pointed to the existence of a second binding site on TLR9, which was characterized in crystal structures that delivered further insights of the nucleic acid recognition of the innate immune system by TLR9.
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Affiliation(s)
- Krisztina Fehér
- Department of Inorganic and Analytical Chemistry, Faculty of Natural Sciences and Technology, Debrecen University, Debrecen, Hungary.,Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
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Tsukamoto Y, Tamura T, Maeda Y, Miyake K, Ato M. N6-methylated adenine on the target sites of mamA from Mycobacterium bovis BCG enhances macrophage activation by CpG DNA in mice. Tuberculosis (Edinb) 2019; 121:101890. [PMID: 32279869 DOI: 10.1016/j.tube.2019.101890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 11/11/2019] [Accepted: 11/15/2019] [Indexed: 01/04/2023]
Abstract
CpG motifs in DNA sequences are recognized by Toll-like receptor 9 and activate immune cells. Bacterial genomic DNA (gDNA) has modified cytosine bases (5-methylcytosine [5 mC]) and modified adenine bases (6-methyladenine [6 mA]). 5 mC inhibits immune activation by CpG DNA; however, it is unclear whether 6 mA inhibits immune activation by CpG DNA. Mycobacterium bovis BCG (BCG) has three adenine methyltransferases (MTases) that act on specific target sequences. In this study, we examined whether the 6 mA at the target sites of adenine MTases affected the immunostimulatory activity of CpG DNA. Our results showed that only 6 mA located at the target sequence of mamA, an adenine MTase from BCG, enhanced interleukin (IL)-12p40 production from murine bone marrow-derived macrophages (BMDMs) stimulated with CpG DNA. Enhancement of IL-12p40 production in BMDMs was also observed when BMDMs were stimulated with CpG DNA ligated to oligodeoxynucleotides (ODNs) harboring 6 mA. Accordingly, we then evaluated whether gDNA from adenine MTase-deficient BCG was less efficient with regard to stimulation of BMDMs. Indeed, gDNA from a mamA-deficient BCG had less ability to activate BMDMs than that from wild-type BCG. We concluded from these results that adenine methylation on ODNs and bacterial gDNA may enhance immune activity induced by CpG DNA.
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Affiliation(s)
- Yumiko Tsukamoto
- Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
| | - Toshiki Tamura
- Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yumi Maeda
- Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kensuke Miyake
- Division of Innate Immunity, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Manabu Ato
- Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan
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