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Loes AN, Hinman MN, Farnsworth DR, Miller AC, Guillemin K, Harms MJ. Identification and Characterization of Zebrafish Tlr4 Coreceptor Md-2. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2021; 206:1046-1057. [PMID: 33472906 PMCID: PMC7889624 DOI: 10.4049/jimmunol.1901288] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 12/16/2020] [Indexed: 12/16/2022]
Abstract
The zebrafish (Danio rerio) is a powerful model organism for studies of the innate immune system. One apparent difference between human and zebrafish innate immunity is the cellular machinery for LPS sensing. In amniotes, the protein complex formed by TLR4 and myeloid differentiation factor 2 (Tlr4/Md-2) recognizes the bacterial molecule LPS and triggers an inflammatory response. It is believed that zebrafish have neither Md-2 nor Tlr4; Md-2 has not been identified outside of amniotes, whereas the zebrafish tlr4 genes appear to be paralogs, not orthologs, of amniote TLR4s We revisited these conclusions. We identified a zebrafish gene encoding Md-2, ly96 Using single-cell RNA sequencing, we found that ly96 is transcribed in cells that also transcribe genes diagnostic for innate immune cells, including the zebrafish tlr4-like genes. In larval zebrafish, ly96 is expressed in a small number of macrophage-like cells. In a functional assay, zebrafish Md-2 and Tlr4ba form a complex that activates NF-κB signaling in response to LPS. In larval zebrafish ly96 loss-of-function mutations perturbed LPS-induced cytokine production but gave little protection against LPS toxicity. Finally, by analyzing the genomic context of tlr4 genes in 11 jawed vertebrates, we found that tlr4 arose prior to the divergence of teleosts and tetrapods. Thus, an LPS-sensitive Tlr4/Md-2 complex is likely an ancestral feature shared by mammals and zebrafish, rather than a de novo invention on the tetrapod lineage. We hypothesize that zebrafish retain an ancestral, low-sensitivity Tlr4/Md-2 complex that confers LPS responsiveness to a specific subset of innate immune cells.
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Affiliation(s)
- Andrea N Loes
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403
| | - Melissa N Hinman
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
- Department of Biology, University of Oregon, Eugene, OR 97403
| | - Dylan R Farnsworth
- Department of Biology, University of Oregon, Eugene, OR 97403
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403; and
| | - Adam C Miller
- Department of Biology, University of Oregon, Eugene, OR 97403
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403; and
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
- Department of Biology, University of Oregon, Eugene, OR 97403
- Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Michael J Harms
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403;
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR 97403
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Mathew AS, Gorick CM, Price RJ. Single-cell mapping of focused ultrasound-transfected brain. Gene Ther 2021; 30:255-263. [PMID: 33526842 PMCID: PMC8325700 DOI: 10.1038/s41434-021-00226-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 12/01/2020] [Accepted: 01/15/2021] [Indexed: 12/15/2022]
Abstract
Gene delivery via focused ultrasound (FUS) mediated blood-brain barrier (BBB) opening is a disruptive therapeutic modality. Unlocking its full potential will require an understanding of how FUS parameters (e.g., peak-negative pressure (PNP)) affect transfected cell populations. Following plasmid (mRuby) delivery across the BBB with 1 MHz FUS, we used single-cell RNA-sequencing to ascertain that distributions of transfected cell types were highly dependent on PNP. Cells of the BBB (i.e., endothelial cells, pericytes, and astrocytes) were enriched at 0.2 MPa PNP, while transfection of cells distal to the BBB (i.e., neurons, oligodendrocytes, and microglia) was augmented at 0.4 MPa PNP. PNP-dependent differential gene expression was observed for multiple cell types. Cell stress genes were upregulated proportional to PNP, independent of cell type. Our results underscore how FUS may be tuned to bias transfection toward specific brain cell types in vivo and predict how those cells will respond to transfection.
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Affiliation(s)
- A S Mathew
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - C M Gorick
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - R J Price
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA. .,Department of Radiology & Medical Imaging, University of Virginia, Charlottesville, VA, USA.
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Zheng W, Xu Q, Zhang Y, E X, Gao W, Zhang M, Zhai W, Rajkumar RS, Liu Z. Toll-like receptor-mediated innate immunity against herpesviridae infection: a current perspective on viral infection signaling pathways. Virol J 2020; 17:192. [PMID: 33298111 PMCID: PMC7726878 DOI: 10.1186/s12985-020-01463-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 12/01/2020] [Indexed: 12/12/2022] Open
Abstract
Background In the past decades, researchers have demonstrated the critical role of Toll-like receptors (TLRs) in the innate immune system. They recognize viral components and trigger immune signal cascades to subsequently promote the activation of the immune system. Main body Herpesviridae family members trigger TLRs to elicit cytokines in the process of infection to activate antiviral innate immune responses in host cells. This review aims to clarify the role of TLRs in the innate immunity defense against herpesviridae, and systematically describes the processes of TLR actions and herpesviridae recognition as well as the signal transduction pathways involved. Conclusions Future studies of the interactions between TLRs and herpesviridae infections, especially the subsequent signaling pathways, will not only contribute to the planning of effective antiviral therapies but also provide new molecular targets for the development of antiviral drugs.
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Affiliation(s)
- Wenjin Zheng
- School of Basic Medical Sciences, Weifang Medical University, Weifang, 261053, China
| | - Qing Xu
- School of Anesthesiology, Weifang Medical University, Weifang, 261053, China
| | - Yiyuan Zhang
- School of Basic Medical Sciences, Weifang Medical University, Weifang, 261053, China
| | - Xiaofei E
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Wei Gao
- Key Lab for Immunology in Universities of Shandong Province, School of Basic Medical Sciences, Weifang Medical University, Weifang, 261053, China
| | - Mogen Zhang
- School of Basic Medical Sciences, Weifang Medical University, Weifang, 261053, China
| | - Weijie Zhai
- School of Basic Medical Sciences, Weifang Medical University, Weifang, 261053, China
| | | | - Zhijun Liu
- Department of Medical Microbiology, School of Basic Medical Sciences, Weifang Medical University, Weifang, 261053, China.
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Yang HJ, Kong B, Shuai W, Zhang JJ, Huang H. MD1 deletion exaggerates cardiomyocyte autophagy induced by heart failure with preserved ejection fraction through ROS/MAPK signalling pathway. J Cell Mol Med 2020; 24:9300-9312. [PMID: 32648659 PMCID: PMC7417689 DOI: 10.1111/jcmm.15579] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/07/2020] [Accepted: 06/10/2020] [Indexed: 12/28/2022] Open
Abstract
In our previous studies, we reported that myeloid differentiation protein 1 (MD1) serves as a negative regulator in several cardiovascular diseases. However, the role of MD1 in heart failure with preserved ejection fraction (HFpEF) and the underlying mechanisms of its action remain unclear. Eight‐week‐old MD1‐knockout (MD1‐KO) and wild‐type (WT) mice served as models of HFpEF induced by uninephrectomy, continuous saline or d‐aldosterone infusion and a 1.0% sodium chloride treatment in drinking water for 4 weeks to investigate the effect of MD1 on HFpEF in vivo. H9C2 cells were treated with aldosterone to evaluate the role of MD1 KO in vitro. MD1 expression was down‐regulated in the HFpEF mice; HFpEF significantly increased the levels of intracellular reactive oxygen species (ROS) and promoted autophagy; and in the MD1‐KO mice, the HFpEF‐induced intracellular ROS and autophagy effects were significantly exacerbated. Moreover, MD1 loss activated the p38‐MAPK pathway both in vivo and in vitro. Aldosterone‐mediated cardiomyocyte autophagy was significantly inhibited in cells pre‐treated with the ROS scavenger N‐acetylcysteine (NAC) or p38 inhibitor SB203580. Furthermore, inhibition with the autophagy inhibitor 3‐methyladenine (3‐MA) offset the aggravating effect of aldosterone‐induced autophagy in the MD1‐KO mice and cells both in vivo and in vitro. Our results validate a critical role of MD1 in the pathogenesis of HFpEF. MD1 deletion exaggerates cardiomyocyte autophagy in HFpEF via the activation of the ROS‐mediated MAPK signalling pathway.
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Affiliation(s)
- Hong-Jie Yang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuchang, China.,Cardiovascular Research Institute, Wuhan University, Wuchang, China.,Hubei Key Laboratory of Cardiology, Wuchang, China
| | - Bin Kong
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuchang, China.,Cardiovascular Research Institute, Wuhan University, Wuchang, China.,Hubei Key Laboratory of Cardiology, Wuchang, China
| | - Wei Shuai
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuchang, China.,Cardiovascular Research Institute, Wuhan University, Wuchang, China.,Hubei Key Laboratory of Cardiology, Wuchang, China
| | - Jing-Jing Zhang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuchang, China.,Cardiovascular Research Institute, Wuhan University, Wuchang, China.,Hubei Key Laboratory of Cardiology, Wuchang, China
| | - He Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuchang, China.,Cardiovascular Research Institute, Wuhan University, Wuchang, China.,Hubei Key Laboratory of Cardiology, Wuchang, China
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Wang Z, Ni X, Zhang L, Sun L, Zhu X, Zhou Q, Yang Z, Yuan H. Toll-Like Receptor 4 and Inflammatory Micro-Environment of Pancreatic Islets in Type-2 Diabetes Mellitus: A Therapeutic Perspective. Diabetes Metab Syndr Obes 2020; 13:4261-4272. [PMID: 33204132 PMCID: PMC7666984 DOI: 10.2147/dmso.s279104] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022] Open
Abstract
Patients with type-2 diabetes mellitus (T2DM) display chronic low-grade inflammation induced by activation of the innate immune system. Toll-like receptor (TLR)4 is a pattern recognition receptor that plays a vital part in activation of the innate immune system. Results from animal and computer-simulation studies have demonstrated that targeting TLR4 to block the TLR4-nuclear factor-kappa B (NF-κB) pathway reduces the inflammatory response and complications associated with T2DM. Therefore, TLR4-targeted therapy has broad prospects. Here, we reviewed the role of TLR4 in inflammation during chronic hyperglycemia in T2DM and its therapeutic prospects.
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Affiliation(s)
- Zhaoping Wang
- The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, People’s Republic of China
| | - Xiaolin Ni
- The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, People’s Republic of China
- Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, People’s Republic of China
| | - Li Zhang
- The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, People’s Republic of China
| | - Liang Sun
- The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, People’s Republic of China
| | - Xiaoquan Zhu
- The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, People’s Republic of China
| | - Qi Zhou
- The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, People’s Republic of China
| | - Ze Yang
- The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, People’s Republic of China
| | - Huiping Yuan
- The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Beijing, People’s Republic of China
- Correspondence: Huiping Yuan The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology, Dongdan DaHua Road 1#, Beijing100730, People’s Republic of ChinaTel +86-10-58115043Fax +86-10-65237929 Email
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Yang J, Yang C, Yang J, Ding J, Li X, Yu Q, Guo X, Fan Z, Wang H. RP105 alleviates myocardial ischemia reperfusion injury via inhibiting TLR4/TRIF signaling pathways. Int J Mol Med 2018; 41:3287-3295. [PMID: 29512709 PMCID: PMC5881694 DOI: 10.3892/ijmm.2018.3538] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/12/2018] [Indexed: 02/06/2023] Open
Abstract
The Toll-like receptor 4 (TLR4) signal pathway- induced inflammation is considered to be a crucial link to myocardial ischemia reperfusion injury (MIRI). Our previous study proved that radioprotective 105 kDa protein (RP105), a negative regulator of TLR4, performed a protective role in MIRI by anti-apoptosis approach. However, the mechanism of RP105 cardioprotection of anti-inflammation is still unclear. This study aimed to explore the underlying mechanism of RP105 anti-inflammation effect in MIRI. We established a rat model of MIRI induced by ligation of the left anterior descending coronary artery for 30 min followed by 2 h reperfusion. Animals were pre-infected with Ad-EGFP-RP105, Ad-EGFP or saline at the apex of the heart. All rats were sacrificed to collect blood samples and myocardial tissue and assessed by immunofluorescence, blood biochemical analysis, Evans blue/triphenyltetrazolium chloride (TTC), hematoxylin and eosin (H&E) staining, enzyme-linked immuno sorbent assay (ELISA), western blot analysis, quantitative PCR and electrophoretic mobility shift assay (EMSA). RP105 overexpression with adenovirus vectors reduced serum myocardial enzyme (CK-MB and LDH) activities, decreased myocardial infarct size, mitigated inflammatory factors interferon-β and tumor necrosis factor-α during MIRI. We also found that Ad-RP105 group exerted distinct repression of TLR4/TRIF signal pathway related proteins and mRNAs (TRIF, TBK-1, IRF3 and p-IRF3) with a low transcriptional activity of IRF3. These findings first expounded that RP105 could alleviate the ischemia reperfusion induced inflammatory status in heart via inhibiting TLR4/TRIF signaling pathway and provided a theoretical foundation of RP105 gene in MIRI.
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Affiliation(s)
- Jun Yang
- Department of Cardiology, The First College of Clinical Medical Sciences, China Three Gorges University, Yichang, Hubei 443000, P.R. China
| | - Chaojun Yang
- Institute of Cardiovascular Diseases, China Three Gorges University, Yichang, Hubei 443000, P.R. China
| | - Jian Yang
- Department of Cardiology, The First College of Clinical Medical Sciences, China Three Gorges University, Yichang, Hubei 443000, P.R. China
| | - Jiawang Ding
- Department of Cardiology, The First College of Clinical Medical Sciences, China Three Gorges University, Yichang, Hubei 443000, P.R. China
| | - Xinxin Li
- Department of Cardiology, The First College of Clinical Medical Sciences, China Three Gorges University, Yichang, Hubei 443000, P.R. China
| | - Qinqin Yu
- Department of Cardiology, The First College of Clinical Medical Sciences, China Three Gorges University, Yichang, Hubei 443000, P.R. China
| | - Xin Guo
- Department of Cardiology, The First College of Clinical Medical Sciences, China Three Gorges University, Yichang, Hubei 443000, P.R. China
| | - Zhixing Fan
- Institute of Cardiovascular Diseases, China Three Gorges University, Yichang, Hubei 443000, P.R. China
| | - Huibo Wang
- Institute of Cardiovascular Diseases, China Three Gorges University, Yichang, Hubei 443000, P.R. China
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Deficiency of TLR4 homologue RP105 aggravates outward remodeling in a murine model of arteriovenous fistula failure. Sci Rep 2017; 7:10269. [PMID: 28860634 PMCID: PMC5578984 DOI: 10.1038/s41598-017-10108-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 07/26/2017] [Indexed: 12/15/2022] Open
Abstract
Arteriovenous access dysfunction is a major cause of morbidity for hemodialysis patients. The pathophysiology of arteriovenous fistula (AVF) maturation failure is associated with inflammation, impaired outward remodeling (OR) and intimal hyperplasia. RP105 is a critical physiologic regulator of TLR4 signaling in numerous cell types. In the present study, we investigated the impact of RP105 on AVF maturation, and defined cell-specific effects of RP105 on macrophages and vascular smooth muscle cells (VSMCs). Overall, RP105−/− mice displayed a 26% decrease in venous OR. The inflammatory response in RP105−/− mice was characterized by accumulation of anti-inflammatory macrophages, a 76% decrease in pro- inflammatory macrophages, a 70% reduction in T-cells and a 50% decrease in MMP-activity. In vitro, anti-inflammatory macrophages from RP105−/− mice displayed increased IL10 production, while MCP1 and IL6 levels secreted by pro-inflammatory macrophages were elevated. VSMC content in RP105−/− AVFs was markedly decreased. In vitro, RP105−/− venous VSMCs proliferation was 50% lower, whereas arterial VSMCs displayed a 50% decrease in migration, relative to WT. In conclusion, the impaired venous OR in RP105−/− mice could result from of a shift in both macrophages and VSMCs towards a regenerative phenotype, identifying a novel relationship between inflammation and VSMC function in AVF maturation.
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Loss of MD1 exacerbates pressure overload-induced left ventricular structural and electrical remodelling. Sci Rep 2017; 7:5116. [PMID: 28698617 PMCID: PMC5505950 DOI: 10.1038/s41598-017-05379-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 05/30/2017] [Indexed: 12/24/2022] Open
Abstract
Myeloid differentiation protein 1 (MD1) has been implicated in numerous pathophysiological processes, including immune regulation, obesity, insulin resistance, and inflammation. However, the role of MD1 in cardiac remodelling remains incompletely understood. We used MD1-knockout (KO) mice and their wild-type littermates to determine the functional significance of MD1 in the regulation of aortic banding (AB)-induced left ventricular (LV) structural and electrical remodelling and its underlying mechanisms. After 4 weeks of AB, MD1-KO hearts showed substantial aggravation of LV hypertrophy, fibrosis, LV dilation and dysfunction, and electrical remodelling, which resulted in overt heart failure and increased electrophysiological instability. Moreover, MD1-KO-AB cardiomyocytes showed increased diastolic sarcoplasmic reticulum (SR) Ca2+ leak, reduced Ca2+ transient amplitude and SR Ca2+ content, decreased SR Ca2+-ATPase2 expression, and increased phospholamban and Na+/Ca2+-exchanger 1 protein expression. Mechanistically, the adverse effects of MD1 deletion on LV remodelling were related to hyperactivated CaMKII signalling and increased impairment of intracellular Ca2+ homeostasis, whereas the increased electrophysiological instability was partly attributed to exaggerated prolongation of cardiac repolarisation, decreased action potential duration alternans threshold, and increased diastolic SR Ca2+ leak. Therefore, our study on MD1 could provide new therapeutic strategies for preventing/treating heart failure.
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Rahimifard M, Maqbool F, Moeini-Nodeh S, Niaz K, Abdollahi M, Braidy N, Nabavi SM, Nabavi SF. Targeting the TLR4 signaling pathway by polyphenols: A novel therapeutic strategy for neuroinflammation. Ageing Res Rev 2017; 36:11-19. [PMID: 28235660 DOI: 10.1016/j.arr.2017.02.004] [Citation(s) in RCA: 312] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/11/2017] [Accepted: 02/16/2017] [Indexed: 01/08/2023]
Abstract
A wide array of cell signaling mediators and their interactions play vital roles in neuroinflammation associated with ischemia, brain trauma, developmental disorders and age-related neurodegeneration. Along with neurons, microglia and astrocytes are also affected by the inflammatory cascade by releasing pro-inflammatory cytokines, chemokines and reactive oxygen species. The release of pro-inflammatory mediators in response to neural dysfunction may be helpful, neutral or even deleterious to normal cellular survival. Moreover, the important role of NF-κB factors in the central nervous system (CNS) through toll-like receptor (TLR) activation has been well established. This review demonstrates recent findings regarding therapeutic aspects of polyphenolic compounds for the treatment of neuroinflammation, with the aim of regulating TLR4. Polyphenols including flavonoids, phenolic acids, phenolic alcohols, stilbenes and lignans, can target TLR4 signaling pathways in multiple ways. Toll interacting protein expression could be modulated by epigallocatechin-3-gallate. Resveratrol may also exert neuroprotective effects via the TLR4/NF-κB/STAT signaling cascade. Its role in activation of cascade via interfering with TLR4 oligomerization upon receptor stimulation has also been reported. Curcumin, another polyphenol, can suppress overexpression of inflammatory mediators via inhibiting the TLR4-MAPK/NF-κB pathway. It can also reduce neuronal apoptosis via a mechanism concerning the TLR4/MyD88/NF-κB signaling pathway in microglia/macrophages. Despite a symphony of in vivo and in vitro studies, many molecular and pharmacological aspects of neuroinflammation remain unclear. It is proposed that natural compounds targeting TLR4 may serve as important pharmacophores for the development of potent drugs for the treatment of neurological disorders.
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Immunoregulatory Effects Triggered by Lactic Acid Bacteria Exopolysaccharides: New Insights into Molecular Interactions with Host Cells. Microorganisms 2016; 4:microorganisms4030027. [PMID: 27681921 PMCID: PMC5039587 DOI: 10.3390/microorganisms4030027] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 06/10/2016] [Indexed: 01/02/2023] Open
Abstract
Researchers have demonstrated that lactic acid bacteria (LAB) with immunomodulatory capabilities (immunobiotics) exert their beneficial effects through several molecules, including cell wall, peptidoglycan, and exopolysaccharides (EPS), that are able to interact with specific host cell receptors. EPS from LAB show a wide heterogeneity in its composition, meaning that biological properties depend on the strain and. therefore, only a part of the mechanism of action has been elucidated for these molecules. In this review, we summarize the current knowledge of the health-promoting actions of EPS from LAB with special focus on their immunoregulatory actions. In addition, we describe our studies using porcine intestinal epithelial cells (PIE cells) as a model to evaluate the molecular interactions of EPS from two immunobiotic LAB strains and the host cells. Our studies showed that EPS from immunobiotic LAB have anti-inflammatory capacities in PIE cells since they are able to reduce the production of inflammatory cytokines in cells challenged with the Toll-like receptor (TLR)-4-agonist lipopolysaccharide. The effects of EPS were dependent on TLR2, TLR4, and negative regulators of TLR signaling. We also reported that the radioprotective 105 (RP105)/MD1 complex, a member of the TLR family, is partially involved in the immunoregulatory effects of the EPS from LAB. Our work described, for the first time, that LAB and their EPS reduce inflammation in intestinal epithelial cells in a RP105/MD1-dependent manner. A continuing challenge for the future is to reveal more effector-receptor relationships in immunobiotic-host interactions that contribute to the beneficial effects of these bacteria on mucosal immune homeostasis. A detailed molecular understanding should lead to a more rational use of immunobiotics in general, and their EPS in particular, as efficient prevention and therapies for specific immune-related disorders in humans and animals.
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Roles of B Cell-Intrinsic TLR Signals in Systemic Lupus Erythematosus. Int J Mol Sci 2015; 16:13084-105. [PMID: 26068236 PMCID: PMC4490487 DOI: 10.3390/ijms160613084] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 05/31/2015] [Accepted: 06/03/2015] [Indexed: 12/16/2022] Open
Abstract
Toll-like receptors (TLRs) are a large family of pattern recognition receptors. TLR signals are involved in the pathogenesis of systemic lupus erythematosus. Mouse and human B cells constitutively express most TLRs. Many B cell subpopulations are highly responsive to certain TLR ligation, including B-1 B cells, transitional B cells, marginal zone B cells, germinal center B cell and memory B cells. The B cell-intrinsic TLR signals play critical roles during lupus process. In this review, roles of B cell-intrinsic TLR2, 4, 7, 8 and 9 signals are discussed during lupus pathogenesis in both mouse model and patients. Moreover, mechanisms underlying TLR ligation-triggered B cell activation and signaling pathways are highlighted.
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Candel S, Sepulcre MP, Espín-Palazón R, Tyrkalska SD, de Oliveira S, Meseguer J, Mulero V. Md1 and Rp105 regulate innate immunity and viral resistance in zebrafish. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2015; 50:155-165. [PMID: 25681741 DOI: 10.1016/j.dci.2015.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/19/2015] [Accepted: 01/21/2015] [Indexed: 06/04/2023]
Abstract
TLR4 was the first TLR family member identified in mammals and is responsible for the activation of the immune response by bacterial LPS. Later, MD1 and RP105 were shown to form complexes that directly interact with the MD2-TLR4 complex, acting as physiological negative regulators of LPS signaling. Despite the general conservation of various TLR families from fish to mammals, several differences can be appreciated, such as the high tolerance of fish to LPS, the absence of the crucial accessory molecules Md2 and Cd14 for Tlr4 signaling in fish, the absence of Tlr4 in some fish species, and the confirmation that LPS does not signal through Tlr4 in zebrafish. The present study has identified the Rp105 and Md1 homologs in zebrafish, confirming (i) Rp105 and Tlr4 evolved from a common ancestor before the divergence between fish and tetrapods and (ii) the presence of Md1 in teleost fish and the lack of Md2, suggesting that the divergence of these accessory molecules occurred in the tetrapod lineage. Biochemical and functional studies indicate that Md1 binds both Rp105 and Tlr4 in zebrafish. Genetic inhibition of zebrafish Md1 and Rp105 reveals that Md1 or Rp105 deficiency impairs the expression of genes encoding pro-inflammatory and antiviral molecules, leading to increased susceptibility to viral infection. These results shed light on the evolutionary history of Md1 and Rp105 and uncover a previously unappreciated function of these molecules in the regulation of innate immunity.
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Affiliation(s)
- Sergio Candel
- Departamento de Biología Celular e Histología, Facultad de Biología, IMIB-Arrixaca, Universidad de Murcia, Murcia 30100, Spain
| | - María P Sepulcre
- Departamento de Biología Celular e Histología, Facultad de Biología, IMIB-Arrixaca, Universidad de Murcia, Murcia 30100, Spain
| | - Raquel Espín-Palazón
- Departamento de Biología Celular e Histología, Facultad de Biología, IMIB-Arrixaca, Universidad de Murcia, Murcia 30100, Spain
| | - Sylwia D Tyrkalska
- Departamento de Biología Celular e Histología, Facultad de Biología, IMIB-Arrixaca, Universidad de Murcia, Murcia 30100, Spain; Instituto de Investigaciones Marinas, CSIC, Vigo, Spain
| | - Sofía de Oliveira
- Departamento de Biología Celular e Histología, Facultad de Biología, IMIB-Arrixaca, Universidad de Murcia, Murcia 30100, Spain; Carlota Saldanha Lab, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - José Meseguer
- Departamento de Biología Celular e Histología, Facultad de Biología, IMIB-Arrixaca, Universidad de Murcia, Murcia 30100, Spain
| | - Victoriano Mulero
- Departamento de Biología Celular e Histología, Facultad de Biología, IMIB-Arrixaca, Universidad de Murcia, Murcia 30100, Spain.
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Fordham JB, Naqvi AR, Nares S. Regulation of miR-24, miR-30b, and miR-142-3p during macrophage and dendritic cell differentiation potentiates innate immunity. J Leukoc Biol 2015; 98:195-207. [PMID: 25990241 DOI: 10.1189/jlb.1a1014-519rr] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 04/17/2015] [Indexed: 01/07/2023] Open
Abstract
miRNAs are ubiquitous regulators of human biology. Parallel profiling of in vitro monocyte-to-Mφ and monocyte-to-DC differentiation revealed static, convergent, and divergent expression of miRNA. Bioinformatic and network analysis of differentially expressed miRNAs implicated miR-24, miR-30b, and miR-142-3p as negative regulators of intracellular signaling pathways, triggered not only by differentiation factors (M-CSF/GM-CSF/IL-4) but also from PRRs. Manipulation of miR-24, miR-30b, and miR-142-3p expression during the differentiation of mD-Mφ and mD-DC differentiation had minimal impact on the acquisition of phenotype but significantly abrogated the ability of these cells to mount inflammatory responses to pathogen-associated stimuli. Forced expression of these miRNAs, which are down-regulated during differentiation, inhibited release of inflammatory cytokines [TNF-α, IL-12(p40), IL-6] upon stimulation with LPS. Functional analysis revealed overlapping mechanisms of inhibition, including surface expression of TLR4/CD14/MD-1 and intracellular PKCα/NF-κB activation. Potential intermediary targets of the TLR4-NF-κB axis included members of the PI3K and MAPK families and PKC isoforms. These results demonstrate the requirement of miR-24, miR-30b, and miR-142-3p down-regulation for the generation of fully functional Mφs and DCs.
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Affiliation(s)
- Jezrom B Fordham
- Department of Periodontics, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Afsar R Naqvi
- Department of Periodontics, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Salvador Nares
- Department of Periodontics, University of Illinois at Chicago, Chicago, Illinois, USA
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14
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Bhushan S, Tchatalbachev S, Lu Y, Fröhlich S, Fijak M, Vijayan V, Chakraborty T, Meinhardt A. Differential activation of inflammatory pathways in testicular macrophages provides a rationale for their subdued inflammatory capacity. THE JOURNAL OF IMMUNOLOGY 2015; 194:5455-64. [PMID: 25917085 DOI: 10.4049/jimmunol.1401132] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 04/01/2015] [Indexed: 01/11/2023]
Abstract
Spermatogenic cells express cell-specific molecules with the potential to be seen as "foreign" by the immune system. Owing to the time difference between their appearance in puberty and the editing of the lymphocyte repertoire around birth, local adaptations of the immune system coined immune privilege are required to confer protection from autoattack. Testicular macrophages (TM) play an important role in maintaining testicular immune privilege and display reduced proinflammatory capacity compared with other macrophages. However, the molecular mechanism underlying this macrophage phenotype remained elusive. We demonstrate that TM have a lower constitutive expression of TLR pathway-specific genes compared with peritoneal macrophages. Moreover, in TM stimulated with LPS, the NF-κB signaling pathway is blocked due to lack of IκBα ubiquitination and, hence, degradation. Instead, challenge of TM with LPS or polyinosinic-polycytidylic acid induces MAPK, AP-1, and CREB signaling pathways, which leads to production of proinflammatory cytokines such as TNF-α, although at much lower levels than in peritoneal macrophages. Pretreatment of TM with inhibitors for MAPKs p38 and ERK1/2 suppresses activation of AP-1 and CREB signaling pathways and attenuates LPS-induced TNF-α and IL-10 secretion. High levels of IL-10 production and activation of STAT3 by LPS stimulation in TM indicate a regulatory macrophage phenotype. Our results suggest that TM maintain testicular immune privilege by inhibiting NF-κB signaling through impairment of IκBα ubiquitination and a general reduction of TLR cascade gene expression. However, TM do maintain some capacity for innate immune responses through AP-1 and CREB signaling pathways.
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Affiliation(s)
- Sudhanshu Bhushan
- Department of Anatomy and Cell Biology, Justus Liebig University Giessen, 35392 Giessen, Germany; and
| | - Svetlin Tchatalbachev
- Department of Medical Microbiology, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Yongning Lu
- Department of Anatomy and Cell Biology, Justus Liebig University Giessen, 35392 Giessen, Germany; and
| | - Suada Fröhlich
- Department of Anatomy and Cell Biology, Justus Liebig University Giessen, 35392 Giessen, Germany; and
| | - Monika Fijak
- Department of Anatomy and Cell Biology, Justus Liebig University Giessen, 35392 Giessen, Germany; and
| | - Vijith Vijayan
- Department of Anatomy and Cell Biology, Justus Liebig University Giessen, 35392 Giessen, Germany; and
| | - Trinad Chakraborty
- Department of Medical Microbiology, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Andreas Meinhardt
- Department of Anatomy and Cell Biology, Justus Liebig University Giessen, 35392 Giessen, Germany; and
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15
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Abstract
Numerous reports have described Toll-like receptor (TLR) functions in myeloid cells such as dendritic cells (DCs) and macrophages, but relatively fewer studies have examined TLR responses in B lymphocytes. B cells express a wide variety of TLRs and are highly activated after TLR ligation, leading to enhancements in B cell survival, surface molecule expression, cytokine and antibody production, and antigen presentation. During an immune response, B cells can receive signals through TLRs as well as the B cell antigen receptor (BCR) and/or CD40. TLR ligation synergizes with signals through these receptors and augments both innate and adaptive immune functions of B lymphocytes. Additionally, targeting B cell TLRs may provide new therapies against certain types of cancer as well as autoimmune diseases. Here, we summarize TLR expression and contributions to both normal and pathogenic functions in mouse and human B cells.
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Affiliation(s)
- Claire M Buchta
- Graduate Program in Immunology, University of Iowa, Iowa City, IA, 52242, USA
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16
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Daringer NM, Schwarz KA, Leonard JN. Contributions of unique intracellular domains to switchlike biosensing by Toll-like receptor 4. J Biol Chem 2015; 290:8764-77. [PMID: 25694428 DOI: 10.1074/jbc.m114.610063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Indexed: 01/23/2023] Open
Abstract
Toll-like receptors (TLRs) mediate immune recognition of both microbial infections and tissue damage. Aberrant TLR signaling promotes disease; thus, understanding the regulation of TLR signaling is of medical relevance. Although downstream mediators of TLR signaling have been identified, the detailed mechanism by which ligand binding-mediated dimerization induces downstream signaling remains poorly understood. Here, we investigate this question for TLR4, which mediates responsiveness to bacterial LPS and drives inflammatory disease. TLR4 exhibits structural and functional features that are unique among TLRs, including responsiveness to a wide variety of ligands. However, the connection between these structural features and the regulation of signaling is not clear. Here, we investigated how the unique intracellular structures of TLR4 contribute to receptor signaling. Key conclusions include the following. 1) The unique intracellular linker of TLR4 is important for achieving LPS-inducible signaling via Toll/IL-1 receptor (TIR) domain-containing adapter-inducing interferon-β (TRIF) but less so for signaling via myeloid differentiation primary response 88 (MyD88). 2) Membrane-bound TLR4 TIR domains were sufficient to induce signaling. However, introducing long, flexible intracellular linkers neither induced constitutive signaling nor ablated LPS-inducible signaling. Thus, the initiation of TLR4 signaling is regulated by a mechanism that does not require tight geometric constraints. Together, these observations necessitate refining the model of TLR4 signal initiation. We hypothesize that TLR4 may interact with an inhibitory partner in the absence of ligand, via both TIR and extracellular domains of TLR4. In this speculative model, ligand binding induces dissociation of the inhibitory partner, triggering spontaneous, switchlike TIR domain homodimerization to initiate downstream signaling.
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Affiliation(s)
| | | | - Joshua N Leonard
- From the Department of Chemical and Biological Engineering, the Chemistry of Life Processes Institute, and the Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Evanston, Illinois 60208
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Wezel A, van der Velden D, Maassen JM, Lagraauw HM, de Vries MR, Karper JC, Kuiper J, Bot I, Quax PHA. RP105 deficiency attenuates early atherosclerosis via decreased monocyte influx in a CCR2 dependent manner. Atherosclerosis 2014; 238:132-9. [PMID: 25484103 DOI: 10.1016/j.atherosclerosis.2014.11.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/20/2014] [Accepted: 11/18/2014] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Toll like receptor 4 (TLR4) plays a key role in inflammation and previously it was established that TLR4 deficiency attenuates atherosclerosis. RadioProtective 105 (RP105) is a structural homolog of TLR4 and an important regulator of TLR4 signaling, suggesting that RP105 may also be an important effector in atherosclerosis. We thus aimed to determine the role of RP105 in atherosclerotic lesion development using RP105 deficient mice on an atherosclerotic background. METHODS AND RESULTS Atherosclerosis was induced in Western-type diet fed low density lipoprotein receptor deficient (LDLr(-/-)) and LDLr/RP105 double knockout (LDLr(-/-)/RP105(-/-)) mice by means of perivascular carotid artery collar placement. Lesion size was significantly reduced by 58% in LDLr(-/-)/RP105(-/-) mice, and moreover, plaque macrophage content was markedly reduced by 40%. In a model of acute peritonitis, monocyte influx was almost 3-fold reduced in LDLr(-/-)/RP105(-/-) mice (P = 0.001), while neutrophil influx remained unaltered, suggestive of an altered migratory capacity of monocytes upon deletion of RP105. Interestingly, in vitro stimulation of monocytes with LPS induced a downregulation of CCR2, a chemokine receptor crucially involved in monocyte influx to atherosclerotic lesions, which was more pronounced in LDLr(-/-)/RP105(-/-) monocytes as compared to LDLr(-/-) monocytes. CONCLUSION We here show that RP105 deficiency results in reduced early atherosclerotic plaque development with a marked decrease in lesional macrophage content, which may be due to disturbed migration of RP105 deficient monocytes resulting from CCR2 downregulation.
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Affiliation(s)
- Anouk Wezel
- Division of Biopharmaceutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands; Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands
| | - Daniël van der Velden
- Division of Biopharmaceutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands; Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Johanna M Maassen
- Division of Biopharmaceutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - H Maxime Lagraauw
- Division of Biopharmaceutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Margreet R de Vries
- Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Jacco C Karper
- Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Johan Kuiper
- Division of Biopharmaceutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Ilze Bot
- Division of Biopharmaceutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands; Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands
| | - Paul H A Quax
- Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands.
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18
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Murofushi Y, Villena J, Morie K, Kanmani P, Tohno M, Shimazu T, Aso H, Suda Y, Hashiguchi K, Saito T, Kitazawa H. The toll-like receptor family protein RP105/MD1 complex is involved in the immunoregulatory effect of exopolysaccharides from Lactobacillus plantarum N14. Mol Immunol 2014; 64:63-75. [PMID: 25466614 DOI: 10.1016/j.molimm.2014.10.027] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 10/28/2014] [Accepted: 10/29/2014] [Indexed: 01/10/2023]
Abstract
The radioprotective 105 (RP105)/MD1 complex is a member of the Toll-like receptor (TLR) family. It was reported that RP105/MD1 cooperates with the lipopolysaccharide (LPS) receptor TLR4/MD2 complex and plays a crucial role in the response of immune cells to LPS. This work evaluated whether RP105, TLR4 or TLR2 were involved in the immunoregulatory capacities of Lactobacillus plantarum N14 (LP14) or its exopolysaccharides (EPS). EPS from LP14 were fractionated into neutral (NPS) and acidic (APS) EPS by anion exchange chromatography. Experiments with transfectant HEK(RP105/MD1) and HEK(TLR2) cells demonstrated that LP14 strongly activated NF-κB via RP105 and TLR2. When we studied the capacity of APS to activate NF-κB pathway in HEK(RP105/MD1) and HEK(TLR4) cells; we observed that APS strongly stimulated both transfectant cells. Our results also showed that LP14 and APS were able to decrease the production of pro-inflammatory cytokines (IL-6, IL-8 and MCP-1) in porcine intestinal epithelial (PIE) cells in response to enterotoxigenic Escherichia coli (ETEC) challenge. In order to confirm the role of TLR2, TLR4 and RP105 in the immunoregulatory effect of APS from LP14, we used small interfering RNA (siRNA) to knockdown these receptors in PIE cells. The capacity of LP14 and APS to modulate pro-inflammatory cytokine expression was significantly reduced in PIE(RP105-/-) cells. It was also shown that LP14 and APS were capable of upregulating negative regulators of the TLR signaling in PIE cells. This work describes for the first time that a Lactobacillus strain and its EPS reduce inflammation in intestinal epithelial cells in a RP105/MD1-dependend manner.
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Affiliation(s)
- Yo Murofushi
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai 981-8555, Japan.
| | - Julio Villena
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai 981-8555, Japan; Laboratory of Immunobiotechnology, CERELA-CONICET, Tucuman, Argentina.
| | - Kyoko Morie
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai 981-8555, Japan.
| | - Paulraj Kanmani
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai 981-8555, Japan.
| | - Masanori Tohno
- Functional Feed Research Team, National Institute of Livestock and Grassland Science, National Agricultural Research Organization, Nasushiobara, Tochigi 329-2793, Japan.
| | - Tomoyuki Shimazu
- Laboratory of Animal Breeding and Genetics, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai 981-8555, Japan.
| | - Hisashi Aso
- Cell Biology Laboratory, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai 981-8555, Japan.
| | - Yoshihito Suda
- Department of Food, Agriculture and Environment, Miyagi University, Sendai 982-0215, Japan.
| | | | - Tadao Saito
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai 981-8555, Japan.
| | - Haruki Kitazawa
- Food and Feed Immunology Group, Graduate School of Agricultural Science, Tohoku University, Aobaku, Sendai 981-8555, Japan.
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19
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RP105 deficiency aggravates cardiac dysfunction after myocardial infarction in mice. Int J Cardiol 2014; 176:788-93. [PMID: 25156852 DOI: 10.1016/j.ijcard.2014.07.086] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Revised: 07/24/2014] [Accepted: 07/26/2014] [Indexed: 12/24/2022]
Abstract
BACKGROUND Toll-like receptor-4 (TLR4), a receptor of the innate immune system, is suggested to have detrimental effects on cardiac function after myocardial infarction (MI). RP105 (CD180) is a TLR4 homolog lacking the intracellular signaling domain that competitively inhibits TLR4-signaling. Thus, we hypothesized that RP105 deficiency, by amplifying TLR4 signaling, would lead to aggravated cardiac dysfunction after MI. METHODS AND RESULTS First, whole blood from RP105-/- and wild-type (WT) male C57Bl/6N mice was stimulated with LPS, which induced a strong inflammatory TNFα response in RP105-/- mice. Then, baseline heart function was assessed by left ventricular pressure-volume relationships which were not different between RP105-/- and WT mice. Permanent ligation of the left anterior descending coronary artery was performed to induce MI. Infarct sizes were analyzed by (immuno)histology and did not differ. Fifteen days post MI heart function was assessed and RP105-/- mice had significantly higher heart rate (+21%, P<0.01), end systolic volume index (+57%, P<0.05), end systolic pressure (+22%, P<0.05) and lower relaxation time constant tau (-12%, P<0.05), and a tendency for increased end diastolic volume index (+42%, P<0.06), compared to WT mice. In the area adjacent to the infarct zone, compared to the healthy myocardium, levels of RP105, TLR4 and the endogenous TLR4 ligand fibronectin-EDA were increased as well as the number of macrophages, however this was not different between both groups. CONCLUSION Deficiency of the endogenous TLR4 inhibitor RP105 leads to an enhanced inflammatory status and more pronounced cardiac dilatation after induction of MI, underscoring the role of the TLR4 pathway in post-infarction remodeling.
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20
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Kane BA, Bryant KJ, McNeil HP, Tedla NT. Termination of immune activation: an essential component of healthy host immune responses. J Innate Immun 2014; 6:727-38. [PMID: 25033984 PMCID: PMC6741560 DOI: 10.1159/000363449] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 05/07/2014] [Accepted: 05/07/2014] [Indexed: 12/15/2022] Open
Abstract
The ideal immune response is rapid, proportionate and effective. Crucially, it must also be finite. An inflammatory response which is disproportionate or lasts too long risks injury to the host; chronic un-regulated inflammation in autoimmune diseases is one example of this. Thus, mechanisms to regulate and ultimately terminate immune responses are central to a healthy immune system. Despite extensive knowledge of what drives immune responses, our understanding of mechanisms of immune termination remains relatively sparse. It is clear that such processes are more complex than a one-dimensional homeostatic balance. Recent discoveries have revealed ever more nuanced mechanisms of signal termination, such as intrinsically self-limiting signals, multiple inhibitory mechanisms acting in tandem and activating proteins behaving differently in a variety of contexts. This review will summarise some important mechanisms, including termination by immunoreceptor tyrosine-based inhibitory motifs (ITIM), inhibition by soluble antagonists, receptor endocytosis or ubiquitination, and auto-inhibition by newly synthesised intracellular inhibitory molecules. Several recent discoveries showing immunoreceptor tyrosine-based activation motifs transducing inhibitory signals, ITIM mediating activating responses and the possible roles of immunoreceptor tyrosine-based switch motifs will also be explored.
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Affiliation(s)
- Barry A. Kane
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, N.S.W., Australia
| | - Katherine J. Bryant
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, N.S.W., Australia
- South Western Sydney Clinical School, University of New South Wales, Sydney, N.S.W., Australia
| | - H. Patrick McNeil
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, N.S.W., Australia
- South Western Sydney Clinical School, University of New South Wales, Sydney, N.S.W., Australia
| | - Nicodemus T. Tedla
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, N.S.W., Australia
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21
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Jones SE, Paynich ML, Kearns DB, Knight KL. Protection from intestinal inflammation by bacterial exopolysaccharides. THE JOURNAL OF IMMUNOLOGY 2014; 192:4813-20. [PMID: 24740503 DOI: 10.4049/jimmunol.1303369] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Host inflammatory responses against pathogenic organisms can be abrogated by commensals; however, the molecular mechanisms by which pathogenesis is prevented are still poorly understood. Previous studies demonstrated that administration of a single dose of Bacillus subtilis prevented disease and inflammation by the enteric mouse pathogen Citrobacter rodentium, which causes disease similar to the human pathogen enteropathogenic Escherichia coli. No protection was observed when an exopolysaccharide (EPS)-deficient mutant of B. subtilis was used, suggesting that EPS are the protective factor. In this study, we isolated and characterized EPS and showed that they also prevent C. rodentium-associated intestinal disease after a single injection. Protection is TLR4 dependent because EPS-treated TLR4 knockout mice developed disease. Furthermore, protection could be conveyed to wild-type mice by adoptive transfer of macrophage-rich peritoneal cells from EPS-treated mice. We found that EPS specifically bind peritoneal macrophages, and because mice lacking MyD88 signaling in myeloid cells were not protected by EPS, we conclude that bacterial EPS prevent colitis in a TLR4-dependent manner that requires myeloid cells. These studies provide a simple means of preventing intestinal inflammation caused by enteric pathogens.
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Affiliation(s)
- Sara E Jones
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL 60153
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22
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Liu B, Fu Y, Feng S, Zhang X, Liu Z, Cao Y, Li D, Liang D, Li F, Zhang N, Yang Z. Involvement of RP105 and toll-like receptors in the activation of mouse peritoneal macrophages by Staphylococcus aureus. Scand J Immunol 2013; 78:8-16. [PMID: 23521167 DOI: 10.1111/sji.12050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 03/12/2013] [Indexed: 12/24/2022]
Abstract
Staphylococcus aureus is the aetiological agent of many hospital- and community-acquired infections. Toll-like receptor 2 (TLR2) has been shown to play a crucial role in the host defence against S. aureus infection. The aim of this study is to investigate the roles of the heterogeneous TLR family proteins TLR2, TLR4 and RP105 during S. aureus infection. Peritoneal macrophages from mice were exposed to S. aureus. Their production of inflammatory cytokines and chemokines, their expression of cell-surface markers and interactions between TLR2, TLR4 and RP105 were assessed in the presence or absence of inhibitory antibodies against TLR2, TLR4/MD-2 and RP105/MD-1 complexes. Our results demonstrate that not only TLR2 but also TLR4 and RP105 are involved in the response of macrophages to S. aureus, that TLR2, TLR4 and RP105 physically interact with each other during S. aureus infection, and that TLR2, TLR4 and RP105 both cooperate and play unique roles in the production of inflammatory cytokines (TNF-α, IL-12p40 and IL-10) and chemokine (RANTES) by macrophages after S. aureus infection. This study characterizes the important roles that TLR2, TLR4 and RP105 play in host resistance against S. aureus infection.
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Affiliation(s)
- B Liu
- College of Animal Science and Veterinary Medicine, Jilin University, Changchun, China
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23
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TLR accessory molecule RP105 (CD180) is involved in post-interventional vascular remodeling and soluble RP105 modulates neointima formation. PLoS One 2013; 8:e67923. [PMID: 23844130 PMCID: PMC3699456 DOI: 10.1371/journal.pone.0067923] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 05/23/2013] [Indexed: 12/12/2022] Open
Abstract
Background RP105 (CD180) is TLR4 homologue lacking the intracellular TLR4 signaling domain and acts a TLR accessory molecule and physiological inhibitor of TLR4-signaling. The role of RP105 in vascular remodeling, in particular post-interventional remodeling is unknown. Methods and Results TLR4 and RP105 are expressed on vascular smooth muscle cells (VSMC) as well as in the media of murine femoral artery segments as detected by qPCR and immunohistochemistry. Furthermore, the response to the TLR4 ligand LPS was stronger in VSMC from RP105−/− mice resulting in a higher proliferation rate. In RP105−/− mice femoral artery cuff placement resulted in an increase in neointima formation as compared to WT mice (4982±974 µm2 vs.1947±278 µm2,p = 0.0014). Local LPS application augmented neointima formation in both groups, but in RP105−/− mice this effect was more pronounced (10316±1243 µm2 vs.4208±555 µm2,p = 0.0002), suggesting a functional role for RP105. For additional functional studies, the extracellular domain of murine RP105 was expressed with or without its adaptor protein MD1 and purified. SEC-MALSanalysis showed a functional 2∶2 homodimer formation of the RP105-MD1 complex. This protein complex was able to block the TLR4 response in whole blood ex-vivo. In vivo gene transfer of plasmid vectors encoding the extracellular part of RP105 and its adaptor protein MD1 were performed to initiate a stable endogenous soluble protein production. Expression of soluble RP105-MD1 resulted in a significant reduction in neointima formation in hypercholesterolemic mice (2500±573 vs.6581±1894 µm2,p<0.05), whereas expression of the single factors RP105 or MD1 had no effect. Conclusion RP105 is a potent inhibitor of post-interventional neointima formation.
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24
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Cannabinoid receptor 2 protects against acute experimental sepsis in mice. Mediators Inflamm 2013; 2013:741303. [PMID: 23781122 PMCID: PMC3679685 DOI: 10.1155/2013/741303] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/30/2013] [Accepted: 05/08/2013] [Indexed: 01/29/2023] Open
Abstract
The systemic inflammatory response syndrome can be self-limited or can progress to severe sepsis and septic shock. Despite significant advances in the understanding of the molecular and cellular mechanisms of septic shock, it is still one of the most frequent and serious problems confronting clinicians in the treatments. And the effects of cannabinoid receptor 2 (CB2R) on the sepsis still remain undefined. The present study was aimed to explore the role and mechanism of CB2R in acute sepsis model of mice. Here, we found that mice were more vulnerable for lipopolysaccharide- (LPS-) induced death and inflammation after CB2R deletion (CB2R−/−). CB2R agonist, GW405833, could significantly extend the survival rate and decrease serum proinflammatory cytokines in LPS-treated mice. GW405833 dose-dependently inhibits proinflammatory cytokines release in splenocytes and peritoneal macrophages as well as splenocytes proliferation, and these effects were partly abolished in CB2R−/− splenocytes but completely abolished in CB2R−/− peritoneal macrophages. Further studies showed that GW405833 inhibits LPS-induced phosphorylation of ERK1/2 and STAT3 and blocks IκBα degradation and NF-κB p65 nuclear translocation in macrophages. All data together showed that CB2R provides a protection and is a potential therapeutic target for the sepsis.
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25
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RP105 involved in activation of mouse macrophages via TLR2 and TLR4 signaling. Mol Cell Biochem 2013; 378:183-93. [PMID: 23483427 DOI: 10.1007/s11010-013-1609-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 03/02/2013] [Indexed: 02/06/2023]
Abstract
RP105 is a member of the toll-like receptor family of proteins that transmits an activation signal in B cells, playing a role in regulation of B cell growth and death; in macrophages and dendritic cells, RP105 is a specific inhibitor of TLR4 signaling. RP105 is uniquely important for regulating TLR4-dependent signaling. It also proved that RP105 is closely related to TLR2 in macrophage activation by Mycobacterium tuberculosis lipoproteins. The aim of our study is to investigate the role of RP105 in mouse macrophages activation of TLR4 and TLR2 signaling by lipopolysaccharides (LPS) and Pam3CysSerLys4 (Pam3CSK4) alone or in combination, and the interaction between TLR2 and TLR4 signaling through RP105. Our results indicate that besides exhibiting negative regulation of TNF-α and IL12-p40 secretion in macrophage activated by LPS, RP105 is also involved in macrophages activation by Pam3CSK4 through TLR2 signaling and exhibited regulation to IL-10 and RANTES production by mouse peritoneal macrophage activated by Pam3CSK4. In macrophages activation by LPS and Pam3CSK4 in combination, TLR2 signaling can overcome RP105-mediated regulation of TLR4 signaling. Thus, our data demonstrate that not only TLR4 signaling, but also RP105 appears to be an essential accessory for immune responses through TLR2 signaling. The function of TLR2 and TLR4 in response to TLR ligands could be associated with each other by RP105. These results can help us understanding the unique role of RP105 in macrophages response to TLR ligands.
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Hutchinson MR, Northcutt AL, Hiranita T, Wang X, Lewis SS, Thomas J, van Steeg K, Kopajtic TA, Loram LC, Sfregola C, Galer E, Miles NE, Bland ST, Amat J, Rozeske RR, Maslanik T, Chapman TR, Strand KA, Fleshner M, Bachtell RK, Somogyi AA, Yin H, Katz JL, Rice KC, Maier SF, Watkins LR. Opioid activation of toll-like receptor 4 contributes to drug reinforcement. J Neurosci 2012; 32:11187-200. [PMID: 22895704 PMCID: PMC3454463 DOI: 10.1523/jneurosci.0684-12.2012] [Citation(s) in RCA: 231] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 06/14/2012] [Accepted: 06/25/2012] [Indexed: 01/08/2023] Open
Abstract
Opioid action was thought to exert reinforcing effects solely via the initial agonism of opioid receptors. Here, we present evidence for an additional novel contributor to opioid reward: the innate immune pattern-recognition receptor, toll-like receptor 4 (TLR4), and its MyD88-dependent signaling. Blockade of TLR4/MD2 by administration of the nonopioid, unnatural isomer of naloxone, (+)-naloxone (rats), or two independent genetic knock-outs of MyD88-TLR4-dependent signaling (mice), suppressed opioid-induced conditioned place preference. (+)-Naloxone also reduced opioid (remifentanil) self-administration (rats), another commonly used behavioral measure of drug reward. Moreover, pharmacological blockade of morphine-TLR4/MD2 activity potently reduced morphine-induced elevations of extracellular dopamine in rat nucleus accumbens, a region critical for opioid reinforcement. Importantly, opioid-TLR4 actions are not a unidirectional influence on opioid pharmacodynamics, since TLR4(-/-) mice had reduced oxycodone-induced p38 and JNK phosphorylation, while displaying potentiated analgesia. Similar to our recent reports of morphine-TLR4/MD2 binding, here we provide a combination of in silico and biophysical data to support (+)-naloxone and remifentanil binding to TLR4/MD2. Collectively, these data indicate that the actions of opioids at classical opioid receptors, together with their newly identified TLR4/MD2 actions, affect the mesolimbic dopamine system that amplifies opioid-induced elevations in extracellular dopamine levels, therefore possibly explaining altered opioid reward behaviors. Thus, the discovery of TLR4/MD2 recognition of opioids as foreign xenobiotic substances adds to the existing hypothesized neuronal reinforcement mechanisms, identifies a new drug target in TLR4/MD2 for the treatment of addictions, and provides further evidence supporting a role for central proinflammatory immune signaling in drug reward.
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MESH Headings
- Analgesics, Opioid/administration & dosage
- Analgesics, Opioid/blood
- Analysis of Variance
- Animals
- Conditioning, Operant/drug effects
- Conditioning, Operant/physiology
- Dopamine/metabolism
- Dose-Response Relationship, Drug
- Drug Administration Routes
- Hyperalgesia/drug therapy
- Hyperalgesia/physiopathology
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Transgenic
- Microdialysis
- Mitogen-Activated Protein Kinase 1/metabolism
- Models, Molecular
- Myeloid Differentiation Factor 88/deficiency
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/metabolism
- Pain Threshold/drug effects
- Pain Threshold/physiology
- Phosphorylation/drug effects
- Protein Binding/drug effects
- Protein Binding/genetics
- Rats
- Rats, Sprague-Dawley
- Reaction Time/drug effects
- Reinforcement, Psychology
- Self Administration
- Signal Transduction/drug effects
- Time Factors
- Toll-Like Receptor 4/agonists
- Toll-Like Receptor 4/deficiency
- Toll-Like Receptor 4/metabolism
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Affiliation(s)
- M R Hutchinson
- Department of Psychology and Neuroscience, University of Colorado-Boulder, Boulder, Colorado 80309, USA
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Tavares AH, Derengowski LS, Ferreira KS, Silva SS, Macedo C, Bocca AL, Passos GA, Almeida SR, Silva-Pereira I. Murine dendritic cells transcriptional modulation upon Paracoccidioides brasiliensis infection. PLoS Negl Trop Dis 2012; 6:e1459. [PMID: 22235359 PMCID: PMC3250510 DOI: 10.1371/journal.pntd.0001459] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 11/18/2011] [Indexed: 02/02/2023] Open
Abstract
Limited information is available regarding the modulation of genes involved in the innate host response to Paracoccidioides brasiliensis, the etiologic agent of paracoccidioidomycosis. Therefore, we sought to characterize, for the first time, the transcriptional profile of murine bone marrow-derived dendritic cells (DCs) at an early stage following their initial interaction with P. brasiliensis. DCs connect innate and adaptive immunity by recognizing invading pathogens and determining the type of effector T-cell that mediates an immune response. Gene expression profiles were analyzed using microarray and validated using real-time RT-PCR and protein secretion studies. A total of 299 genes were differentially expressed, many of which are involved in immunity, signal transduction, transcription and apoptosis. Genes encoding the cytokines IL-12 and TNF-α, along with the chemokines CCL22, CCL27 and CXCL10, were up-regulated, suggesting that P. brasiliensis induces a potent proinflammatory response in DCs. In contrast, pattern recognition receptor (PRR)-encoding genes, particularly those related to Toll-like receptors, were down-regulated or unchanged. This result prompted us to evaluate the expression profiles of dectin-1 and mannose receptor, two other important fungal PRRs that were not included in the microarray target cDNA sequences. Unlike the mannose receptor, the dectin-1 receptor gene was significantly induced, suggesting that this β-glucan receptor participates in the recognition of P. brasiliensis. We also used a receptor inhibition assay to evaluate the roles of these receptors in coordinating the expression of several immune-related genes in DCs upon fungal exposure. Altogether, our results provide an initial characterization of early host responses to P. brasiliensis and a basis for better understanding the infectious process of this important neglected pathogen. Paracoccidioidomycosis is a systemic disease that has an important mortality and morbidity impact in Latin America, mainly affecting rural workers of Argentina, Colombia, Venezuela and Brazil. Upon host infection, one of the most important aspects contributing to disease outcome is the initial encounter of the Paracoccidioides brasiliensis fungus with dendritic cells. This phagocytic cell is specialized in decoding microbial information and triggering specific immune responses. Thus, using a molecular biology technique to examine the response of thousand of genes, we aimed to identify the ways in which murine dendritic cells interact with P. brasiliensis during an early time point following infection. This approach allowed us to recognize diverse modulated genes, in particular those associated with a proinflamatory response and fungal recognition. Our work provides an initial molecular characterization of early infection process and should promote further investigations into the innate host response to this important fungal pathogen.
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Affiliation(s)
- Aldo H. Tavares
- Faculdade de Ceilândia, Universidade de Brasília, Brasília, Brasil
| | | | - Karen S. Ferreira
- Departamento de Ciências Biológicas, Universidade Federal de São Paulo, São Paulo, Brasil
| | - Simoneide S. Silva
- Departamento de Biologia Celular, Universidade de Brasília, Brasília, Brasil
| | - Cláudia Macedo
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brasil
| | - Anamélia L. Bocca
- Departamento de Biologia Celular, Universidade de Brasília, Brasília, Brasil
| | - Geraldo A. Passos
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brasil
| | - Sandro R. Almeida
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brasil
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Meyer-Bahlburg A, Rawlings DJ. Differential impact of Toll-like receptor signaling on distinct B cell subpopulations. Front Biosci (Landmark Ed) 2012; 17:1499-516. [PMID: 22201817 DOI: 10.2741/4000] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
B cells exhibit a range of functional responses following TLR engagement including immunoglobulin and cytokine production, proliferation, antigen presentation and migration. However, B cell intrinsic TLR responses appear to be precisely programmed based upon the developmental stage of the cell. B cell subpopulations classified as innate immune cells including marginal zone and B-1 B cells exhibit robust responses to TLR stimulation. In contrast, activation of other B cell subsets is constrained via a variety of developmentally regulated events. In this review we provide an overview of TLR responses in murine and human B cells and specifically highlight patterns of TLR expression and developmentally regulated functional responses.
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Affiliation(s)
- Almut Meyer-Bahlburg
- Department of Pediatric Pneumology, Allergy and Neonatology, Hannover Medical School, D-30625 Germany.
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29
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Hanke ML, Kielian T. Toll-like receptors in health and disease in the brain: mechanisms and therapeutic potential. Clin Sci (Lond) 2011; 121:367-87. [PMID: 21745188 PMCID: PMC4231819 DOI: 10.1042/cs20110164] [Citation(s) in RCA: 370] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The discovery of mammalian TLRs (Toll-like receptors), first identified in 1997 based on their homology with Drosophila Toll, greatly altered our understanding of how the innate immune system recognizes and responds to diverse microbial pathogens. TLRs are evolutionarily conserved type I transmembrane proteins expressed in both immune and non-immune cells, and are typified by N-terminal leucine-rich repeats and a highly conserved C-terminal domain termed the TIR [Toll/interleukin (IL)-1 receptor] domain. Upon stimulation with their cognate ligands, TLR signalling elicits the production of cytokines, enzymes and other inflammatory mediators that can have an impact on several aspects of CNS (central nervous system) homoeostasis and pathology. For example, TLR signalling plays a crucial role in initiating host defence responses during CNS microbial infection. Furthermore, TLRs are targets for many adjuvants which help shape pathogen-specific adaptive immune responses in addition to triggering innate immunity. Our knowledge of TLR expression and function in the CNS has greatly expanded over the last decade, with new data revealing that TLRs also have an impact on non-infectious CNS diseases/injury. In particular, TLRs recognize a number of endogenous molecules liberated from damaged tissues and, as such, influence inflammatory responses during tissue injury and autoimmunity. In addition, recent studies have implicated TLR involvement during neurogenesis, and learning and memory in the absence of any underlying infectious aetiology. Owing to their presence and immune-regulatory role within the brain, TLRs represent an attractive therapeutic target for numerous CNS disorders and infectious diseases. However, it is clear that TLRs can exert either beneficial or detrimental effects in the CNS, which probably depend on the context of tissue homoeostasis or pathology. Therefore any potential therapeutic manipulation of TLRs will require an understanding of the signals governing specific CNS disorders to achieve tailored therapy.
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Affiliation(s)
- Mark L. Hanke
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Tammy Kielian
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
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30
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An unusual dimeric structure and assembly for TLR4 regulator RP105-MD-1. Nat Struct Mol Biol 2011; 18:1028-35. [PMID: 21857663 DOI: 10.1038/nsmb.2106] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 06/14/2011] [Indexed: 12/29/2022]
Abstract
RP105-MD-1 modulates the TLR4-MD-2-mediated, innate immune response against bacterial lipopolysaccharide (LPS). The crystal structure of the bovine 1:1 RP105-MD-1 complex bound to a putative endogenous lipid at 2.9 Å resolution shares a similar overall architecture to its homolog TLR4-MD-2 but assembles into an unusual 2:2 homodimer that differs from any other known TLR-ligand assembly. The homodimer is assembled in a head-to-head orientation that juxtaposes the N-terminal leucine-rich repeats (LRRs) of the two RP105 chains, rather than the usual tail-to-tail configuration of C-terminal LRRs in ligand-activated TLR dimers, such as TLR1-TRL2, TLR2-TLR6, TLR3-TLR3 and TLR4-TLR4. Another unusual interaction is mediated by an RP105-specific asparagine-linked glycan, which wedges MD-1 into the co-receptor binding concavity on RP105. This unique mode of assembly represents a new paradigm for TLR complexes and suggests a molecular mechanism for regulating LPS responses.
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31
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Okun E, Griffioen KJ, Mattson MP. Toll-like receptor signaling in neural plasticity and disease. Trends Neurosci 2011; 34:269-81. [PMID: 21419501 DOI: 10.1016/j.tins.2011.02.005] [Citation(s) in RCA: 383] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 02/14/2011] [Accepted: 02/14/2011] [Indexed: 01/03/2023]
Abstract
Toll-like receptors (TLRs) are a family of innate immune system receptors that respond to pathogen-derived and tissue damage-related ligands. TLR signaling in immune cells, glia and neurons can play roles in the pathogenesis of stroke, Alzheimer's disease (AD) and multiple sclerosis (MS). Recent findings suggest that TLR signaling also influences multiple dynamic processes in the developing and adult central nervous system including neurogenesis, axonal growth and structural plasticity. In addition, TLRs are implicated in the regulation of behaviors including learning, memory and anxiety. This review describes recently discovered and unexpected roles for TLRs in neuroplasticity, and the implications of these findings for future basic and translational research studies.
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Affiliation(s)
- Eitan Okun
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Biomedical Research Center, Baltimore, MD 21224, USA
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32
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Toll-like receptor 4 modulation as a strategy to treat sepsis. Mediators Inflamm 2010; 2010:568396. [PMID: 20396414 PMCID: PMC2855078 DOI: 10.1155/2010/568396] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 03/02/2010] [Indexed: 01/08/2023] Open
Abstract
Despite a decrease in mortality over the last decade, sepsis remains the tenth leading causes of death in western countries and one of the most common cause of death in intensive care units. The recent discovery of Toll-like receptors and their downstream signalling pathways allowed us to better understand the pathophysiology of sepsis-related disorders. Particular attention has been paid to Toll-like receptor 4, the receptor for Gram-negative bacteria outer membrane lipopolysaccharide or endotoxin. Since most of the clinical trial targeting single inflammatory cytokine in the treatment of sepsis failed, therapeutic targeting of Toll-like receptor 4, because of its central role, looks promising. The purpose of this paper is to focus on the recent data of various drugs targeting TLR4 expression and pathway and their potential role as adjunctive therapy in severe sepsis and septic shock.
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Davila S, Hibberd ML, Hari Dass R, Wong HEE, Sahiratmadja E, Bonnard C, Alisjahbana B, Szeszko JS, Balabanova Y, Drobniewski F, van Crevel R, van de Vosse E, Nejentsev S, Ottenhoff THM, Seielstad M. Genetic association and expression studies indicate a role of toll-like receptor 8 in pulmonary tuberculosis. PLoS Genet 2008; 4:e1000218. [PMID: 18927625 PMCID: PMC2568981 DOI: 10.1371/journal.pgen.1000218] [Citation(s) in RCA: 195] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 09/08/2008] [Indexed: 01/09/2023] Open
Abstract
Despite high rates of exposure, only 5-10% of people infected with Mycobacterium tuberculosis will develop active tuberculosis (TB) disease, suggesting a significant role for genetic variation in the human immune response to this infection. Here, we studied TB association and expression of 18 genes involved in the Toll-like receptor (TLR) pathways. Initially, we genotyped 149 sequence polymorphisms in 375 pulmonary TB patients and 387 controls from Indonesia. We found that four polymorphisms in the TLR8 gene on chromosome X showed evidence of association with TB susceptibility in males, including a non-synonymous polymorphism rs3764880 (Met1Val; P = 0.007, odds ratio (OR) = 1.8, 95% c.i. = 1.2-2.7). We genotyped these four TLR8 polymorphisms in an independent collection of 1,837 pulmonary TB patients and 1,779 controls from Russia and again found evidence of association in males (for rs3764880 P = 0.03, OR = 1.2, 95% c.i. = 1.02-1.48). Combined evidence for association is P = 1.2x10(-3)-6x10(-4). In addition, a quantitative PCR analysis indicated that TLR8 transcript levels are significantly up-regulated in patients during the acute phase of disease (P = 9.36x10(-5)), relative to baseline levels following successful chemotherapy. A marked increase in TLR8 protein expression was also observed directly in differentiated macrophages upon infection with M. bovis bacille Calmette-Guérin (BCG). Taken together, our results provide evidence, for the first time, of a role for the TLR8 gene in susceptibility to pulmonary TB across different populations.
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Affiliation(s)
- Sonia Davila
- Infectious Diseases, Genome Institute of Singapore, Singapore, Singapore.
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Wang JY, Lin CGJ, Hsiao YH, Liou YH, Wu LSH. Single nucleotide polymorphisms and haplotype of MD-1 gene associated with high serum IgE phenotype with mite-sensitive allergy in Taiwanese children. Int J Immunogenet 2007; 34:407-12. [DOI: 10.1111/j.1744-313x.2007.00711.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Toll-like receptors (TLRs) are essential mediators of both innate and adaptive immunity by recognizing and eliciting responses upon invasion of pathogens. The response of TLRs must be stringently regulated as exaggerated expression of signalling components as well as pro-inflammatory cytokines can have devastating effects on the host, resulting in chronic inflammatory diseases, autoimmune disorders and aid in the pathogenesis of TLR-associated human diseases. Therefore, it is essential that negative regulators act at multiple levels within TLR signalling cascades, as well as through eliciting negative-feedback mechanisms in order to synchronize the positive activation and negative regulation of signal transduction to avert potentially harmful immunological consequences. This review explores the various mechanisms employed by negative regulators to ensure the appropriate modulation of both immune and inflammatory responses.
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Affiliation(s)
- Tali Lang
- Centre for Functional Genomics and Human Disease, Monash Institute of Medical Research, Monash University, Victoria, Australia
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Cavaillon JM, Adib-Conquy M. Bench-to-bedside review: endotoxin tolerance as a model of leukocyte reprogramming in sepsis. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2007; 10:233. [PMID: 17044947 PMCID: PMC1751079 DOI: 10.1186/cc5055] [Citation(s) in RCA: 375] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Endotoxin tolerance is defined as a reduced responsiveness to a lipopolysaccharide (LPS) challenge following a first encounter with endotoxin. Endotoxin tolerance protects against a lethal challenge of LPS and prevents infection and ischemia-reperfusion damage. Endotoxin tolerance is paralleled by a dramatic reduction of tumor necrosis factor (TNF) production and some other cytokines in response to LPS. Endotoxin tolerance involves the participation of macrophages and mediators, such as glucocorticoids, prostaglandins, IL-10, and transforming growth factor-β. Endotoxin tolerance is accompanied by the up-regulation of inhibitory molecules that down-regulate the Toll-like receptor (TLR)4-dependent signaling pathway. Cross-tolerance between LPS and other TLR specific ligands, as well as IL-1 and TNF, has been regularly reported. A similar loss of LPS reactivity has been repeatedly reported in circulating leukocytes of septic patients and in patients with non-infectious systemic inflammation response syndrome (SIRS). Studies on cellular signaling within leukocytes from septic and SIRS patients reveal numerous alterations reminiscent of those observed in endotoxin tolerant cells. However, altered responsiveness to LPS of leukocytes from sepsis and SIRS patients is not synonymous with a global down-regulation of cellular reactivity. The term 'cellular reprogramming', which has been proposed to qualify the process of endotoxin tolerance, defines well the immune status of circulating leukocytes in septic and SIRS patients.
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Affiliation(s)
- Jean-Marc Cavaillon
- Cytokines and Inflammation Unit, Institut Pasteur, rue Dr Roux, 75015 Paris, France.
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