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Tam JSY, Coller JK, Hughes PA, Prestidge CA, Bowen JM. Toll-like receptor 4 (TLR4) antagonists as potential therapeutics for intestinal inflammation. Indian J Gastroenterol 2021; 40:5-21. [PMID: 33666891 PMCID: PMC7934812 DOI: 10.1007/s12664-020-01114-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/27/2020] [Indexed: 02/04/2023]
Abstract
Gastrointestinal inflammation is a hallmark of highly prevalent disorders, including cancer treatment-induced mucositis and ulcerative colitis. These disorders cause debilitating symptoms, have a significant impact on quality of life, and are poorly managed. The activation of toll-like receptor 4 (TLR4) has been proposed to have a major influence on the inflammatory signalling pathways of the intestinal tract. Inhibition of TLR4 has been postulated as an effective way to treat intestinal inflammation. However, there are a limited number of studies looking into the potential of TLR4 antagonism as a therapeutic approach for intestinal inflammation. This review surveyed available literature and reported on the in vitro, ex vivo and in vivo effects of TLR4 antagonism on different models of intestinal inflammation. Of the studies reviewed, evidence suggests that there is indeed potential for TLR4 antagonists to treat inflammation, although only a limited number of studies have investigated treating intestinal inflammation with TLR4 antagonists directly. These results warrant further research into the effect of TLR4 antagonists in the intestinal tract.
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Affiliation(s)
- Janine S. Y. Tam
- Discipline of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, South Australia 5005 Australia
| | - Janet K. Coller
- Discipline of Pharmacology, Adelaide Medical School, University of Adelaide, Adelaide, South Australia Australia
| | - Patrick A. Hughes
- Centre for Nutrition and Gastrointestinal Diseases, Adelaide Medical School, University of Adelaide and South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Clive A. Prestidge
- Clinical and Health Sciences, University of South Australia, Adelaide, South Australia Australia ,ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Melbourne, Australia
| | - Joanne M. Bowen
- Discipline of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, South Australia 5005 Australia
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Yuan T, Yang Z, Xian S, Chen Y, Wang L, Chen W, Long W, Che Y. Dexmedetomidine-mediated regulation of miR-17-3p in H9C2 cells after hypoxia/reoxygenation injury. Exp Ther Med 2020; 20:917-925. [PMID: 32742334 PMCID: PMC7388268 DOI: 10.3892/etm.2020.8775] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 10/30/2019] [Indexed: 01/08/2023] Open
Abstract
Patients with heart disease often suffer from ischemia, which can be treated by reperfusion. However, this treatment can lead to the development of ischemia/reperfusion (I/R) injury, an inflammatory condition that can cause further heart damage. Dexmedetomidine (Dex), an α2-adrenoceptor agonist, and the microRNA (miR)-17-3p, have both been suggested to alleviate I/R injury and cardiac tissue inflammation. The aim of the present study was to investigate whether Dex and miR-17-3p could act together to prevent I/R injury. H9C2 cells, a myoblast cell line used as a model of rat cardiomyocytes, were cultured in a hypoxic environment for 3 h, and then reoxygenated for 3 h. This hypoxia/reoxygenation (H/R) was used to model I/R. Cell Counting kit-8 was used to determine cell viability and an annexin V-FITC/propidium iodide apoptosis kit used to analyze cell apoptosis. A dual luciferase reporter assay was used to determine the interaction between miR-17-3p and toll-like receptor 4 (TLR4). Western blotting and reverse transcription-quantitative PCR were used to determine protein levels and mRNA expression of TLR4 and galectin-3. A concentration of 0.1-10 µmol/l Dex attenuated H/R injury, which was accompanied by increased miR-17-3p levels. Additionally, the inhibition of miR-17-3p exacerbated H/R injury and reduced the effect of Dex on H/R injury. H/R led to an increased galectin-3 level compared with that in control cells, and Dex or miR-17-3p inhibitor did not markedly affect the level of galectin-3, indicating that Dex alleviated the effects of I/R injury through other pathways. Inhibition of miR-17-3p in Dex-induced H9C2 cells during H/R increased the expression of inflammatory mediators including tumor necrosis factor-α, interleukin (IL)-6, IL-1β and phosphorylated NFκB subunit p65, while Dex reduced the H/R-induced expression of these inflammatory mediators. Inhibition of TLR4 also attenuated H/R injury. In summary, the findings of the present study indicated that Dex reduced H/R injury in H9C2 cell via the modulation of inflammatory signaling pathways, and these inflammatory factors could be regulated by miR-17-3p.
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Affiliation(s)
- Tianhui Yuan
- Department of Drug Clinical Trials, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China.,Clinical Research Unit, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China.,Phase I Program, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Zhongqi Yang
- Department of Drug Clinical Trials, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China.,Clinical Research Unit, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China.,Phase I Program, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Shaoxiang Xian
- Department of Chinese Internal Medicine, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Yang Chen
- School of Pharmaceuticals, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Lingjun Wang
- Lingnan Medical Center, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Weitao Chen
- Intensive Care Unit, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Wenjie Long
- College of First Clinical Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Yuanyuan Che
- Department of Cardiology, Zaozhuang Municipal Hospital, Zaozhuang, Shandong 277102, P.R. China
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3
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Li Y, Zhang L, Tang J, Yang X, Huang J, Zhu T, Zhao F, Li S, Li X, Qu Y, Mu D. Role of toll-like receptor 4 in the regulation of the cell death pathway and neuroinflammation. Brain Res Bull 2019; 148:79-90. [DOI: 10.1016/j.brainresbull.2019.03.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 03/25/2019] [Accepted: 03/28/2019] [Indexed: 02/07/2023]
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TLR4 Signaling Pathway Modulators as Potential Therapeutics in Inflammation and Sepsis. Vaccines (Basel) 2017; 5:vaccines5040034. [PMID: 28976923 PMCID: PMC5748601 DOI: 10.3390/vaccines5040034] [Citation(s) in RCA: 333] [Impact Index Per Article: 47.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 09/29/2017] [Accepted: 10/01/2017] [Indexed: 02/06/2023] Open
Abstract
Toll-Like Receptor 4 (TLR4) signal pathway plays an important role in initiating the innate immune response and its activation by bacterial endotoxin is responsible for chronic and acute inflammatory disorders that are becoming more and more frequent in developed countries. Modulation of the TLR4 pathway is a potential strategy to specifically target these pathologies. Among the diseases caused by TLR4 abnormal activation by bacterial endotoxin, sepsis is the most dangerous one because it is a life-threatening acute system inflammatory condition that still lacks specific pharmacological treatment. Here, we review molecules at a preclinical or clinical phase of development, that are active in inhibiting the TLR4-MyD88 and TLR4-TRIF pathways in animal models. These are low-molecular weight compounds of natural and synthetic origin that can be considered leads for drug development. The results of in vivo studies in the sepsis model and the mechanisms of action of drug leads are presented and critically discussed, evidencing the differences in treatment results from rodents to humans.
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A novel function of TLR4 in mediating the immunomodulatory effect of Benzanthrone, an environmental pollutant. Toxicol Lett 2017; 276:69-84. [DOI: 10.1016/j.toxlet.2017.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/02/2017] [Accepted: 05/05/2017] [Indexed: 12/28/2022]
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Barratt-Due A, Pischke SE, Nilsson PH, Espevik T, Mollnes TE. Dual inhibition of complement and Toll-like receptors as a novel approach to treat inflammatory diseases-C3 or C5 emerge together with CD14 as promising targets. J Leukoc Biol 2016; 101:193-204. [PMID: 27581539 PMCID: PMC5166441 DOI: 10.1189/jlb.3vmr0316-132r] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 07/01/2016] [Accepted: 07/25/2016] [Indexed: 12/22/2022] Open
Abstract
Review of how targeting key upstream molecules at the recognition phase of innate immunity exert anti-inflammatory effects; a potential therapeutic regimen for inflammatory diseases. The host is protected by pattern recognition systems, including complement and TLRs, which are closely cross-talking. If improperly activated, these systems might induce tissue damage and disease. Inhibition of single downstream proinflammatory cytokines, such as TNF, IL-1β, and IL-6, have failed in clinical sepsis trials, which might not be unexpected, given the substantial amounts of mediators involved in the pathogenesis of this condition. Instead, we have put forward a hypothesis of inhibition at the recognition phase by “dual blockade” of bottleneck molecules of complement and TLRs. By acting upstream and broadly, the dual blockade could be beneficial in conditions with improper or uncontrolled innate immune activation threatening the host. Key bottleneck molecules in these systems that could be targets for inhibition are the central complement molecules C3 and C5 and the important CD14 molecule, which is a coreceptor for several TLRs, including TLR4 and TLR2. This review summarizes current knowledge of inhibition of complement and TLRs alone and in combination, in both sterile and nonsterile inflammatory processes, where activation of these systems is of crucial importance for tissue damage and disease. Thus, dual blockade might provide a general, broad-acting therapeutic regimen against a number of diseases where innate immunity is improperly activated.
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Affiliation(s)
- Andreas Barratt-Due
- Department of Immunology, Oslo University Hospital, and K. G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway.,Department of Emergencies and Critical Care, Oslo University Hospital, Oslo, Norway
| | - Søren Erik Pischke
- Department of Immunology, Oslo University Hospital, and K. G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway.,Department of Emergencies and Critical Care, Oslo University Hospital, Oslo, Norway
| | - Per H Nilsson
- Department of Immunology, Oslo University Hospital, and K. G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway
| | - Terje Espevik
- Centre of Molecular Inflammation Research and Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Tom Eirik Mollnes
- Department of Immunology, Oslo University Hospital, and K. G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway; .,Centre of Molecular Inflammation Research and Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.,Research Laboratory Nordland Hospital, Bodø, Norway; and.,K. G. Jebsen Thrombosis Research and Expertise Center, University of Tromsø, Tromsø, Norway
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TAK-242, an antagonist for Toll-like receptor 4, protects against acute cerebral ischemia/reperfusion injury in mice. J Cereb Blood Flow Metab 2015; 35:536-42. [PMID: 25586141 PMCID: PMC4420883 DOI: 10.1038/jcbfm.2014.240] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 11/29/2014] [Accepted: 12/03/2014] [Indexed: 02/07/2023]
Abstract
Toll-like receptor 4 (TLR4) contributes to cerebral ischemia/reperfusion (I/R) injury and is a potential target for the treatment of ischemic stroke. This experiment is to evaluate the effect of an exogenous TLR4 antagonist, TAK-242, against acute cerebral I/R injury. A mouse model of cerebral I/R was induced by transient middle cerebral artery occlusion. TAK-242 (3 mg/kg body weight) was injected intraperitoneally 1 hour after ischemia. Our results showed that the concentration of TAK-242 in plasma increased to 52.0 ng/mL 3 hours after injection, was maintained at 54.1 ng/mL 8 hours after injection, and decreased to 22.6 ng/mL 24 hours after injection. The concentration of TAK-242 in brain tissue increased to 26.1 ng/mL in ischemic hemisphere and 14.2 ng/mL in nonischemic hemisphere 3 hours after injection, and was maintained at the similar levels 24 hours after injection. We found that TAK-242 significantly reduced cerebral infarction compared with vehicle control, improved neurologic function, inhibited the phosphorylation of downstream protein kinases in TLR4 signaling pathway, and downregulated the expression of inflammatory cytokines. We conclude that TAK-242 is able to cross blood-brain barrier, blocks TLR4 signaling, mediates the expression of inflammatory cytokines, and protects the brain from acute damage induced by I/R.
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Toll-like receptor 4 contributes to the inhibitory effect of morphine on colonic motility in vitro and in vivo. Sci Rep 2015; 5:9499. [PMID: 25962524 PMCID: PMC5386182 DOI: 10.1038/srep09499] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/10/2015] [Indexed: 12/13/2022] Open
Abstract
Opioids rank among the most potent analgesic drugs but gastrointestinal side effects, especially constipation, limit their therapeutic utility. The adverse effects of opioids have been attributed to stimulation of opioid receptors, but emerging evidence suggests that opioids interact with the innate immune receptor Toll-like receptor 4 (TLR4) and its signalling pathway. As TLR4 signalling affects gastrointestinal motility, we examined the involvement of TLR4 in morphine-induced depression of peristaltic motility in the guinea-pig intestine in vitro and male C57BL/6N mice in vivo. While the TLR4 antagonist TAK-242 (0.1 μM and 1 μM) did not alter the morphine-induced inhibition of peristalsis in the isolated guinea-pig small intestine, the morphine-induced decrease in pellet propulsion velocity in colonic segments was attenuated by TAK-242 (0.1 μM). The ability of TAK-242 (4 mg/kg) to mitigate the morphine-induced suppression of colonic motility was replicated in mice in vivo by measuring the expulsion time of beads inserted in the distal colon. The inhibition of upper gastrointestinal transit of mice by morphine was not affected by pre-treatment with TAK-242 (4 mg/kg) in vivo. This is the first report that morphine-induced inhibition of colonic peristalsis is alleviated by TLR4 antagonism. We therefore conclude that TLR4 may contribute to opioid-induced constipation.
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Fenhammar J, Rundgren M, Hultenby K, Forestier J, Taavo M, Kenne E, Weitzberg E, Eriksson S, Ozenci V, Wernerson A, Frithiof R. Renal effects of treatment with a TLR4 inhibitor in conscious septic sheep. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2014; 18:488. [PMID: 25182709 PMCID: PMC4190385 DOI: 10.1186/s13054-014-0488-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 08/04/2014] [Indexed: 12/12/2022]
Abstract
Introduction Acute kidney injury (AKI) is a common and feared complication of sepsis. The pathogenesis of sepsis-induced AKI is largely unknown, and therapeutic interventions are mainly supportive. In the present study, we tested the hypothesis that pharmacological inhibition of Toll-like receptor 4 (TLR4) would improve renal function and reduce renal damage in experimental sepsis, even after AKI had already developed. Methods Sheep were surgically instrumented and subjected to a 36-hour intravenous infusion of live Escherichia coli. After 12 hours, they were randomized to treatment with a selective TLR4 inhibitor (TAK-242) or vehicle. Results The E. coli caused normotensive sepsis characterized by fever, increased cardiac index, hyperlactemia, oliguria, and decreased creatinine clearance. TAK-242 significantly improved creatinine clearance and urine output. The increase in N-acetyl-beta-D-glucosaminidas, a marker of tubular damage, was attenuated. Furthermore, TAK-242 reduced the renal neutrophil accumulation and glomerular endothelial swelling caused by sepsis. These effects were independent of changes in renal artery blood flow and renal microvascular perfusion in both cortex and medulla. TAK-242 had no effect per se on the measured parameters. Conclusions These results show that treatment with a TLR4 inhibitor is able to reverse a manifest impairment in renal function caused by sepsis. In addition, the results provide evidence that the mechanism underlying the effect of TAK-242 on renal function does not involve improved macro-circulation or micro-circulation, enhanced renal oxygen delivery, or attenuation of tubular necrosis. TLR4-mediated inflammation resulting in glomerular endothelial swelling may be an important part of the pathogenesis underlying Gram-negative septic acute kidney injury. Electronic supplementary material The online version of this article (doi:10.1186/s13054-014-0488-y) contains supplementary material, which is available to authorized users.
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Zhou Y, Wang Y, Wang J, Anne Stetler R, Yang QW. Inflammation in intracerebral hemorrhage: from mechanisms to clinical translation. Prog Neurobiol 2013; 115:25-44. [PMID: 24291544 DOI: 10.1016/j.pneurobio.2013.11.003] [Citation(s) in RCA: 437] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 02/07/2023]
Abstract
Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes and is associated with high mortality and morbidity. Currently, no effective medical treatment is available to improve functional outcomes in patients with ICH. Potential therapies targeting secondary brain injury are arousing a great deal of interest in translational studies. Increasing evidence has shown that inflammation is the key contributor of ICH-induced secondary brain injury. Inflammation progresses in response to various stimuli produced after ICH. Hematoma components initiate inflammatory signaling via activation of microglia, subsequently releasing proinflammatory cytokines and chemokines to attract peripheral inflammatory infiltration. Hemoglobin (Hb), heme, and iron released after red blood cell lysis aggravate ICH-induced inflammatory injury. Danger associated molecular patterns such as high mobility group box 1 protein, released from damaged or dead cells, trigger inflammation in the late stage of ICH. Preclinical studies have identified inflammatory signaling pathways that are involved in microglial activation, leukocyte infiltration, toll-like receptor (TLR) activation, and danger associated molecular pattern regulation in ICH. Recent advances in understanding the pathogenesis of ICH-induced inflammatory injury have facilitated the identification of several novel therapeutic targets for the treatment of ICH. This review summarizes recent progress concerning the mechanisms underlying ICH-induced inflammation. We focus on the inflammatory signaling pathways involved in microglial activation and TLR signaling, and explore potential therapeutic interventions by targeting the removal of hematoma components and inhibition of TLR signaling.
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Affiliation(s)
- Yu Zhou
- Department of Neurology, Xinqiao Hospital & The Second Affiliated Hospital, The Third Military Medical University, Chongqing, China
| | - Yanchun Wang
- Department of Neurology, Xinqiao Hospital & The Second Affiliated Hospital, The Third Military Medical University, Chongqing, China
| | - Jian Wang
- Department of Anesthesiology/Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - R Anne Stetler
- Center of Cerebrovascular Disease Research, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Qing-Wu Yang
- Department of Neurology, Xinqiao Hospital & The Second Affiliated Hospital, The Third Military Medical University, Chongqing, China.
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Savva A, Roger T. Targeting toll-like receptors: promising therapeutic strategies for the management of sepsis-associated pathology and infectious diseases. Front Immunol 2013; 4:387. [PMID: 24302927 PMCID: PMC3831162 DOI: 10.3389/fimmu.2013.00387] [Citation(s) in RCA: 191] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 11/05/2013] [Indexed: 01/04/2023] Open
Abstract
Toll-like receptors (TLRs) are pattern recognition receptors playing a fundamental role in sensing microbial invasion and initiating innate and adaptive immune responses. TLRs are also triggered by danger signals released by injured or stressed cells during sepsis. Here we focus on studies developing TLR agonists and antagonists for the treatment of infectious diseases and sepsis. Positioned at the cell surface, TLR4 is essential for sensing lipopolysaccharide of Gram-negative bacteria, TLR2 is involved in the recognition of a large panel of microbial ligands, while TLR5 recognizes flagellin. Endosomal TLR3, TLR7, TLR8, TLR9 are specialized in the sensing of nucleic acids produced notably during viral infections. TLR4 and TLR2 are favorite targets for developing anti-sepsis drugs, and antagonistic compounds have shown efficient protection from septic shock in pre-clinical models. Results from clinical trials evaluating anti-TLR4 and anti-TLR2 approaches are presented, discussing the challenges of study design in sepsis and future exploitation of these agents in infectious diseases. We also report results from studies suggesting that the TLR5 agonist flagellin may protect from infections of the gastrointestinal tract and that agonists of endosomal TLRs are very promising for treating chronic viral infections. Altogether, TLR-targeted therapies have a strong potential for prevention and intervention in infectious diseases, notably sepsis.
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Affiliation(s)
- Athina Savva
- Infectious Diseases Service, Department of Medicine, Centre Hospitalier Universitaire Vaudois, University of Lausanne , Lausanne , Switzerland
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Fang H, Wang PF, Zhou Y, Wang YC, Yang QW. Toll-like receptor 4 signaling in intracerebral hemorrhage-induced inflammation and injury. J Neuroinflammation 2013; 10:27. [PMID: 23414417 PMCID: PMC3598479 DOI: 10.1186/1742-2094-10-27] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 12/31/2012] [Indexed: 12/20/2022] Open
Abstract
Intracerebral hemorrhage (ICH) is a common type of fatal stroke, accounting for about 15% to 20% of all strokes. Hemorrhagic strokes are associated with high mortality and morbidity, and increasing evidence shows that innate immune responses and inflammatory injury play a critical role in ICH-induced neurological deficits. However, the signaling pathways involved in ICH-induced inflammatory responses remain elusive. Toll-like receptor 4 (TLR4) belongs to a large family of pattern recognition receptors that play a key role in innate immunity and inflammatory responses. In this review, we summarize recent findings concerning the involvement of TLR4 signaling in ICH-induced inflammation and brain injury. We discuss the key mechanisms associated with TLR4 signaling in ICH and explore the potential for therapeutic intervention by targeting TLR4 signaling.
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Affiliation(s)
- Huang Fang
- Department of Neurology, Second Affiliated Hospital and Xinqiao Hospital, Third Military Medical University, Xinqiao Zhengjie No,183, Shapingba District, Chongqing 400037, China
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Abstract
Serious infection and the patient's response (sepsis) is a serious health problem that, even today, is associated with a mortality rate of 30 %-50 %. The phases of severe sepsis include an early hyperinflammatory response to pathogens and a late immunosuppressed phase. Toll-like receptors (TLRs) are a family of transmembrane innate immune receptors that play a major role in both phases of sepsis. Here, their physiology and the therapeutic strategies employed to date are reviewed. Currently, there are no approved therapies targeting TLRs, but it is anticipated that in the future, the less-studied TLRs, such as TLR3, TLR7, and TLR9, will evolve therapeutic targets, perhaps predominantly with agonists, versus the usual antagonist strategies. Furthermore, accurately characterizing the stage of sepsis will be essential to directing appropriate therapeutic choices.
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Affiliation(s)
- John H Boyd
- Critical Care Research Laboratories, Heart + Lung Institute, St. Paul's Hospital, University of British Columbia, 1081 Burrard Street, Vancouver, BC, Canada, V6Z 1Y6,
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Suzuki K, Nemoto K, Ninomiya N, Kuno M, Kubota M, Yokota H. Fasudil, a Rho-kinase inhibitor, attenuates lipopolysaccharide-induced vascular hyperpermeability and colonic muscle relaxation in guinea pigs. J Surg Res 2012; 178:352-7. [PMID: 22487385 DOI: 10.1016/j.jss.2012.01.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 01/17/2012] [Accepted: 01/25/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND Rho-associated coiled coil-forming protein kinase (Rho-kinase), a downstream target effector of the small GTP-binding protein Rho, plays a key role in cell adhesion, motility, and contraction. The goal of the present study was to determine the role of the Rho/Rho-kinase signal pathway in the pathogenesis of lipopolysaccharide (LPS)-induced vascular hyperpermeability using the Rho-kinase inhibitor fasudil. METHODS To evaluate plasma leakage, fasudil (3 or 10 mg/kg) or saline was intravenously administered 30 min before LPS injection. LPS (100, 300, and 1,000 μg/0.1 mL/site) and saline (0.1 mL/site) were administered intracutaneously in the dorsum of guinea pigs. Vascular permeability was measured on the dorsal skin by the local accumulation of Evans Blue dye after intracutaneous injection of LPS (100-1000 μg/site) from Escherichia coli. For the measurement of colonic muscle tension, fasudil (3 mg/kg) or saline was intravenously administered 30 min before LPS injection. LPS (1 mg/kg) was administered intravenously. RESULTS Dye leakage in the skin increased significantly 2 h after the injection of LPS. This LPS-induced dye leakage was significantly suppressed by fasudil (3 and 10 mg/kg). LPS caused a transient decrease in colonic muscle tension, which peaked 2.5 h after the injection. This decrease in muscle tension was significantly suppressed by pretreatment with fasudil (3 mg/kg). CONCLUSIONS The Rho/Rho-kinase pathway might play an important role in the pathogenesis of LPS-induced endotoxemia, and fasudil could attenuate LPS-induced microvascular permeability, leading to inhibition of endotoxemia.
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Affiliation(s)
- Kensuke Suzuki
- Department of Emergency and Critical Care Medicine, Nippon Medical School, Tokyo, Japan.
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Liang Q, Wu Q, Jiang J, Duan J, Wang C, Smith MD, Lu H, Wang Q, Nagarkatti P, Fan D. Characterization of sparstolonin B, a Chinese herb-derived compound, as a selective Toll-like receptor antagonist with potent anti-inflammatory properties. J Biol Chem 2011; 286:26470-9. [PMID: 21665946 DOI: 10.1074/jbc.m111.227934] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Blockade of excessive Toll-like receptor (TLR) signaling is a therapeutic approach being actively pursued for many inflammatory diseases. Here we report a Chinese herb-derived compound, sparstolonin B (SsnB), which selectively blocks TLR2- and TLR4-mediated inflammatory signaling. SsnB was isolated from a Chinese herb, Spaganium stoloniferum; its structure was determined by NMR spectroscopy and x-ray crystallography. SsnB effectively inhibited inflammatory cytokine expression in mouse macrophages induced by lipopolysaccharide (LPS, a TLR4 ligand), Pam3CSK4 (a TLR1/TLR2 ligand), and Fsl-1 (a TLR2/TLR6 ligand) but not that by poly(I:C) (a TLR3 ligand) or ODN1668 (a TLR9 ligand). It suppressed LPS-induced cytokine secretion from macrophages and diminished phosphorylation of Erk1/2, p38a, IκBα, and JNK in these cells. In THP-1 cells expressing a chimeric receptor CD4-TLR4, which triggers constitutive NF-κB activation, SsnB effectively blunted the NF-κB activity. Co-immunoprecipitation showed that SsnB reduced the association of MyD88 with TLR4 and TLR2, but not that with TLR9, in HEK293T cells and THP-1 cells overexpressing MyD88 and TLRs. Furthermore, administration of SsnB suppressed splenocyte inflammatory cytokine expression in mice challenged with LPS. These results demonstrate that SsnB acts as a selective TLR2 and TLR4 antagonist by blocking the early intracellular events in the TLR2 and TLR4 signaling. Thus, SssB may serve as a promising lead for the development of selective TLR antagonistic agents for inflammatory diseases.
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Affiliation(s)
- Qiaoli Liang
- Department of Cell Biology and Anatomy, University of South Carolina School of Medicine, Columbia, South Carolina 29209, USA
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De Winter BY, De Man JG. Interplay between inflammation, immune system and neuronal pathways: Effect on gastrointestinal motility. World J Gastroenterol 2010; 16:5523-35. [PMID: 21105185 PMCID: PMC2992670 DOI: 10.3748/wjg.v16.i44.5523] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Sepsis is a systemic inflammatory response representing the leading cause of death in critically ill patients, mostly due to multiple organ failure. The gastrointestinal tract plays a pivotal role in the pathogenesis of sepsis-induced multiple organ failure through intestinal barrier dysfunction, bacterial translocation and ileus. In this review we address the role of the gastrointestinal tract, the mediators, cell types and transduction pathways involved, based on experimental data obtained from models of inflammation-induced ileus and (preliminary) clinical data. The complex interplay within the gastrointestinal wall between mast cells, residential macrophages and glial cells on the one hand, and neurons and smooth muscle cells on the other hand, involves intracellular signaling pathways, Toll-like receptors and a plethora of neuroactive substances such as nitric oxide, prostaglandins, cytokines, chemokines, growth factors, tryptases and hormones. Multidirectional signaling between the different components in the gastrointestinal wall, the spinal cord and central nervous system impacts inflammation and its consequences. We propose that novel therapeutic strategies should target inflammation on the one hand and gastrointestinal motility, gastrointestinal sensitivity and even pain signaling on the other hand, for instance by impeding afferent neuronal signaling, by activation of the vagal anti-inflammatory pathway or by the use of pharmacological agents such as ghrelin and ghrelin agonists or drugs interfering with the endocannabinoid system.
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Toll-like receptors in domestic animals. Cell Tissue Res 2010; 343:107-20. [DOI: 10.1007/s00441-010-1047-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 09/01/2010] [Indexed: 12/13/2022]
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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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