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Hopp MT, Holze J, Lauber F, Holtkamp L, Rathod DC, Miteva MA, Prestes EB, Geyer M, Manoury B, Merle NS, Roumenina LT, Bozza MT, Weindl G, Imhof D. Insights into the molecular basis and mechanism of heme-triggered TLR4 signalling: The role of heme-binding motifs in TLR4 and MD2. Immunology 2024; 171:181-197. [PMID: 37885279 DOI: 10.1111/imm.13708] [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: 05/16/2023] [Accepted: 10/06/2023] [Indexed: 10/28/2023] Open
Abstract
Haemolytic disorders, such as sickle cell disease, are accompanied by the release of high amounts of labile heme into the intravascular compartment resulting in the induction of proinflammatory and prothrombotic complications in affected patients. In addition to the relevance of heme-regulated proteins from the complement and blood coagulation systems, activation of the TLR4 signalling pathway by heme was ascribed a crucial role in the progression of these pathological processes. Heme binding to the TLR4-MD2 complex has been proposed recently, however, essential mechanistic information of the processes at the molecular level, such as heme-binding kinetics, the heme-binding capacity and the respective heme-binding sites (HBMs) is still missing. We report the interaction of TLR4, MD2 and the TLR4-MD2 complex with heme and the consequences thereof by employing biochemical, spectroscopic, bioinformatic and physiologically relevant approaches. Heme binding occurs transiently through interaction with up to four HBMs in TLR4, two HBMs in MD2 and at least four HBMs in their complex. Functional studies highlight that mutations of individual HBMs in TLR4 preserve full receptor activation by heme, suggesting that heme interacts with TLR4 through different binding sites independently of MD2. Furthermore, we confirm and extend the major role of TLR4 for heme-mediated cytokine responses in human immune cells.
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Affiliation(s)
- Marie-T Hopp
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, Bonn, Germany
- Department of Chemistry, Institute of Integrated Natural Sciences, University of Koblenz, Koblenz, Germany
| | - Janine Holze
- Pharmacology and Toxicology, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Felicitas Lauber
- Pharmacology and Toxicology, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Laura Holtkamp
- Pharmacology and Toxicology, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Dhruv C Rathod
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Maria A Miteva
- CNRS UMR 8038 CiTCoM, Université de Paris, Faculté de Pharmacie de Paris, Paris, France
- INSERM U 1268 Medicinal Chemistry and Translational Research, Paris, France
| | - Elisa B Prestes
- Laboratório de Inflamação e Imunidade, Departamento de Imunologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Matthias Geyer
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Bénédicte Manoury
- Institut Necker Enfants Malades, INSERM U1151-CNRS UMR8253, Université Paris Cité, Faculté de médecine Necker, Paris, France
| | - Nicolas S Merle
- Centre de Recherche des Cordeliers, UMR_S 1138, INSERM, Paris, France
- Centre de Recherche des Cordeliers, Sorbonne Universités, Paris, France
- Centre de Recherche des Cordeliers, Université Paris Descartes, Paris, France
| | - Lubka T Roumenina
- Centre de Recherche des Cordeliers, UMR_S 1138, INSERM, Paris, France
- Centre de Recherche des Cordeliers, Sorbonne Universités, Paris, France
- Centre de Recherche des Cordeliers, Université Paris Descartes, Paris, France
| | - Marcelo T Bozza
- Laboratório de Inflamação e Imunidade, Departamento de Imunologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Günther Weindl
- Pharmacology and Toxicology, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Diana Imhof
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, Bonn, Germany
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Li J, Wang W, Yuan Y, Cui X, Bian H, Wen H, Zhang X, Yu H, Wu H. Pinellia ternata lectin induces inflammation through TLR4 receptor and mediates PI3K/Akt/mTOR axis to regulate NF-κB signaling pathway. Toxicology 2023; 486:153430. [PMID: 36669722 DOI: 10.1016/j.tox.2023.153430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/16/2023] [Accepted: 01/17/2023] [Indexed: 01/19/2023]
Abstract
Pinellia ternata, a widely used traditional Chinese medicine, contains a strong mucosal irritant that is connected with Pinellia ternata lectin (PTL) in its tubers. The purpose of this study was to explore the mechanisms by which PTL induces inflammation. We found that in RAW264.7 cells, PTL activated the PI3K/Akt/mTOR and NF-κB pathways, which resulted in the release of proinflammatory cytokines. Flow cytometry and laser confocal microscopy analysis showed that FITC-labeled PTL bound to the macrophages' surface. Based on kinetic analyses and protein-protein docking simulations, PTL was shown to bind toll-like receptor 4 (TLR4).it was demonstrated that PTL binds highly to Toll-like receptor 4 (TLR4). TLR4 knock-down or knockout resulted in a decrease in both cytokine release and PI3K/Akt/mTOR and NF-κB pathway activation in PTL-stimulated macrophages or mice. RNA-seq analysis showed that genes involved in the PI3K/Akt/mTOR signaling pathway were strongly upregulated in response to PTL stimulation, confirming that the PI3K/Akt/mTOR pathway is linked to the inflammatory effect of PTL in RAW264.7 cells. These findings reveal that PTL can mediate inflammation through TLR4 and activating the PI3K/Akt/mTOR to regulate NF-κB signaling pathways.
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Affiliation(s)
- Jinfei Li
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Wei Wang
- Department of Chinese Medicine and Pharmacy, School of Pharmacy, Jiangsu University, Zhenjiang 212013, China
| | - Yuan Yuan
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Xiaobing Cui
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Huimin Bian
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Hongmei Wen
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Xingde Zhang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Hongli Yu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; Jiangsu Key Laboratory of Chinese Medicine Processing, Nanjing University of Chinese Medicine, Nanjing 210023, China; Engineering Center of State Ministry of Education for Standardization of Chinese Medicine Processing, Nanjing 210023, China; State Key Laboratory Cultivation Base for TCM Quality and Efficacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
| | - Hao Wu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; Jiangsu Key Laboratory of Chinese Medicine Processing, Nanjing University of Chinese Medicine, Nanjing 210023, China; Engineering Center of State Ministry of Education for Standardization of Chinese Medicine Processing, Nanjing 210023, China; State Key Laboratory Cultivation Base for TCM Quality and Efficacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
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