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Brusletto BS, Hellerud BC, Øvstebø R, Brandtzaeg P. Neisseria meningitidis accumulate in large organs during meningococcal sepsis. Front Cell Infect Microbiol 2023; 13:1298360. [PMID: 38089821 PMCID: PMC10713808 DOI: 10.3389/fcimb.2023.1298360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 11/07/2023] [Indexed: 12/18/2023] Open
Abstract
Background Neisseria meningitidis (Nm) is the cause of epidemic meningitis and fulminant meningococcal septicemia. The clinical presentations and outcome of meningococcal septic shock is closely related to the circulating levels of lipopolysaccharides (LPS) and of Neisseria meningitidis DNA (Nm DNA). We have previously explored the distribution of Nm DNA in tissues from large organs of patients dying of meningococcal septic shock and in a porcine meningococcal septic shock model. Objective 1) To explore the feasibility of measuring LPS levels in tissues from the large organs in patients with meningococcal septic shock and in a porcine meningococcal septic shock model. 2) To evaluate the extent of contamination of non-specific LPS during the preparation of tissue samples. Patients and methods Plasma, serum, and fresh frozen (FF) tissue samples from the large organs of three patients with lethal meningococcal septic shock and two patients with lethal pneumococcal disease. Samples from a porcine meningococcal septic shock model were included. Frozen tissue samples were thawed, homogenized, and prepared for quantification of LPS by Pyrochrome® Limulus Amoebocyte Lysate (LAL) assay. Results N. meningitidis DNA and LPS was detected in FF tissue samples from large organs in all patients with meningococcal septic shock. The lungs are the organs with the highest LPS and Nm DNA concentration followed by the heart in two of the three meningococcal shock patients. Nm DNA was not detected in any plasma or tissue sample from patients with lethal pneumococcal infection. LPS was detected at a low level in all FF tissues from the two patients with lethal pneumococcal disease. The experimental porcine meningococcal septic shock model indicates that also in porcinis the highest LPS and Nm DNA concentration are detected in lungs tissue samples. The quantification analysis showed that the highest concentration of both Nm DNA and LPS are in the organs and not in the circulation of patients with lethal meningococcal septic shock. This was also shown in the experimental porcine meningococcal septic shock model. Conclusion Our results suggest that LPS can be quantified in mammalian tissues by using the LAL assay.
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Affiliation(s)
| | | | - Reidun Øvstebø
- Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway
| | - Petter Brandtzaeg
- Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway
- Department of Pediatrics, Oslo University Hospital, Nydalen, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
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2
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Walker JM, Sundarasivarao PYK, Thornton JM, Sochacki K, Rodriguez A, Spur BW, Acharya NK, Yin K. Resolvin D2 promotes host defense in a 2 - hit model of sepsis with secondary lung infection. Prostaglandins Other Lipid Mediat 2022; 159:106617. [PMID: 35007703 PMCID: PMC8920764 DOI: 10.1016/j.prostaglandins.2022.106617] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 12/30/2021] [Accepted: 01/03/2022] [Indexed: 12/17/2022]
Abstract
In the development of sepsis, there is early, massive inflammation which can lead to multiple organ failure. Later there is an immunosuppressed phase where the host is susceptible to secondary infections or is unable to clear existing infection. Specialized Pro-resolving Mediators (SPMs) are endogenously produced lipids which resolve infection by decreasing bacteria load and reducing systemic inflammatory response. There has been little work studying if SPMs given late, can promote host defense. We examined if an SPM, Resolvin D2 (RvD2) could promote host defense in a 2-hit mouse model of cecal ligation and puncture (CLP) sepsis and secondary Pseudomonas aeruginosa lung infection. RvD2 given 48 h after mild CLP (1st hit), increased gene expression of Toll-like receptor-2 (TLR-2) and alveolar macrophage/monocyte phagocytic ability compared to CLP mice given saline vehicle. In this model, RvD2 did not affect plasma IL-6 or IL-10. These effects induced by RvD2, lowered lung bacterial load and decreased mortality after the secondary infection of Pseudomonas aeruginosa (2nd hit). Splenic T-cell numbers were also increased in RvD2 treated mice compared to saline vehicle treated animals. The results suggest that RvD2 promoted mechanisms of host defense in a 2-hit model sepsis and secondary lung infection.
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Affiliation(s)
- J M Walker
- Department of Cell Biology and Neuroscience, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA
| | - P Y Kadiyam Sundarasivarao
- Department of Cell Biology and Neuroscience, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA
| | - J M Thornton
- Department of Cell Biology and Neuroscience, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA
| | - K Sochacki
- Department of Cell Biology and Neuroscience, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA
| | - A Rodriguez
- Department of Cell Biology and Neuroscience, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA
| | - B W Spur
- Department of Cell Biology and Neuroscience, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA
| | - N K Acharya
- Department of Cell Biology and Neuroscience, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA; Biomarker Discovery Center, New Jersey Institute of Successful Aging, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA
| | - K Yin
- Department of Cell Biology and Neuroscience, Rowan University - School of Osteopathic Medicine, Stratford, NJ, USA.
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3
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Han Q, Hu R, Li H, Lei Z, Zhang X, Yu X, Zhang Q, Mao Y, Wang X, Irwin DM, Niu G, Tan H. Application of a TLR overexpression cell model in pyrogen detection. Biotechnol Bioeng 2019; 116:1269-1279. [PMID: 30684361 PMCID: PMC6519253 DOI: 10.1002/bit.26936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 01/17/2019] [Accepted: 01/22/2019] [Indexed: 12/20/2022]
Abstract
Pyrogens are components derived from microorganisms that induce complex inflammatory responses. Current approaches to detect pyrogens are complex and difficult to replicate, thus there is a need for new methods to detect pyrogens. We successfully constructed a pyrogen-sensitive cell model by overexpressing Toll-like receptor (TLR)2, TLR4, MD2, and CD14 in HEK293 cells. Since the cytokine IL-6 is specifically released upon stimulation of the TLR2 and TLR4 signaling pathways in response to pyrogen stimulation, we used it as a read out for our assay. Our results show that IL-6 is released in response to trace amounts of pyrogens in our cell model. Pyrogen incubation times and concentrations were explored to determine the sensitivity of our cell model, and was found to be sensitive to 0.05 EU/ml of LPS and 0.05 ug/ml of LTA after stimulation for 5 hr. Our TLR overexpressing cell model, with IL-6 as readout, could be a new method for in vitro testing of pyrogens and applicable for evaluating the safety of drugs.
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Affiliation(s)
- Qing Han
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
| | - Ruobi Hu
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
| | - Hui Li
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
| | - Zhen Lei
- Research and Development DepartmentBeijing N&N Genetech CompanyBeijingChina
| | - Xuehui Zhang
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
| | - Xiuyan Yu
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
| | - Qun Zhang
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
| | - Yiqing Mao
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
| | - Xi Wang
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
| | - David M. Irwin
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
- Department of Laboratory Medicine and PathobiologyUniversity of Toronto, TorontoOntarioCanada
| | - Gang Niu
- Research and Development DepartmentBeijing N&N Genetech CompanyBeijingChina
| | - Huanran Tan
- Department of PharmacologyPeking University, Health Science CenterBeijingChina
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4
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Zhang Y, Shao L. Decreased microRNA-140-5p contributes to respiratory syncytial virus disease through targeting Toll-like receptor 4. Exp Ther Med 2018; 16:993-999. [PMID: 30116350 DOI: 10.3892/etm.2018.6272] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 08/28/2017] [Indexed: 12/24/2022] Open
Abstract
The abnormal expression of miRNAs (miRs) has previously been reported in respiratory syncytial virus (RSV) disease. However, to the best of our knowledge, the expression of miR-140-5p in patients with an RSV infection has never been explored. Reverse transcription-quantitative polymerase chain reaction was performed to analyze the level of miR-140-5p in the blood and nasopharyngeal airway samples. ELISAs were performed to determine the levels of tumor necrosis factor α, interleukin (IL)-1β, IL-6 and IL-8. A dual luciferase reporter assay was also performed to investigate the possible target gene of miR-140-5p. The results demonstrated that the levels of miR-140-5p were significantly decreased in the nasal mucosal and peripheral blood samples of patients with RSV infection. It was also revealed that overexpression of miR-140-5p decreased the inflammatory responses, while inhibition of miR-140-5p enhanced the inflammatory responses. Additionally, three binding sites of miR-140-5p in the 3untranslated region (UTR) of Toll-like receptor (TLR)4 were identified and a dual luciferase reporter assay demonstrated that miR-140-5p significantly suppressed the relative luciferase activity of pmirGLO-TLR4-3UTR. Furthermore, the level of miR-140-5p was shown to be increased following interferon (IFN)α incubation. Notably, inhibition of miR-140-5p markedly attenuated IFNα-mediated downregulation of tumor necrosis factor α, and interleukin-1β, -6 and -8 in BEAS-2B cells. In summary, decreased miR-140-5p levels are involved in RSV-infection diseases primarily through targeting TLR4.
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Affiliation(s)
- Yun Zhang
- Infectious Disease Department, Jiangsu Taizhou People's Hospital, Taizhou, Jiangsu 225300, P.R. China
| | - Lingyun Shao
- Infectious Disease Department, Shanghai Huashan Hospital, Shanghai 200040, P.R. China
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5
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Aass HCD, Hellum M, Trøseid AMS, Brandtzaeg P, Berg JP, Øvstebø R, Henriksson CE. Whole-blood incubation with the Neisseria meningitidis lpxL1 mutant induces less pro-inflammatory cytokines than the wild type, and IL-10 reduces the MyD88-dependent cytokines. Innate Immun 2018; 24:101-111. [PMID: 29313733 PMCID: PMC6830899 DOI: 10.1177/1753425917749299] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Levels of bacterial LPS, pro-inflammatory cytokines and IL-10 are related to the
severity of meningococcal septicaemia. Patients infected with a
Neisseria meninigitidis lpxL1 mutant
(Nm-mutant) with penta-acylated lipid A present with a milder
meningococcal disease than those infected with hexa-acylated Nm
wild type (Nm-wt). The aim was to compare the pro-inflammatory
responses after ex vivo incubation with the heat-inactivated
Nm-wt or the Nm-mutant in citrated whole
blood, and the modulating effects of IL-10. Concomitantly, we measured
intracellular IL-6, IL-8 and TNF-α to elucidate which cell types were
responsible for the pro-inflammatory responses. Incubation with
Nm-wt
(106/ml;107/ml;108/ml) resulted in a
dose-dependent increase of the MyD88-dependent pro-inflammatory cytokines
(IL-1β, IL-6, IL-8, TNF-α), which were mainly derived from monocytes. In
comparison, only 108/ml of the Nm-mutant
significantly increased the concentration of these cytokines. The
MyD88-independent cytokines (IP-10, RANTES) were evidently increased after
incubation with the Nm-wt but were unaffected by the
Nm-mutant. Co-incubation with IL-10 significantly reduced
the concentrations of the MyD88-dependent cytokines induced by both the
Nm-wt and the Nm-mutant, whereas the
MyD88-independent cytokines were almost unaffected. In summary, the
Nm-mutant is a weaker inducer of the
MyD88-dependent/independent cytokines than the Nm-wt in whole
blood, and IL-10 attenuates the Nm-stimulated increase in
MyD88-dependent pro-inflammatory cytokines.
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Affiliation(s)
- Hans Christian D Aass
- 1 Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.,2 Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Marit Hellum
- 1 Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.,2 Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | | | - Petter Brandtzaeg
- 1 Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.,2 Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,3 Department of Pediatrics, University of Oslo, Oslo, Norway
| | - Jens Petter Berg
- 1 Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.,2 Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Reidun Øvstebø
- 1 Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway
| | - Carola Elisabeth Henriksson
- 1 Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.,2 Institute of Clinical Medicine, University of Oslo, Oslo, Norway
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6
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Bjerre A, Brusletto B, Øvstebø R, Joø GB, Kierulf P, Brandtzaeg P. Identification of meningococcal LPS as a major monocyte activator in IL-10 depleted shock plasmas and CSF by blocking the CD14-TLR4 receptor complex. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519030090030301] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have examined the in vitro stimulatory effects of lipopolysaccharide (LPS)-containing samples (meningococcal shock plasma, n = 10; non-shock plasma, n = 10; cerebrospinal fluid (CSF), n = 7) before and after immunodepletion of interleukin (IL)-10 in a monocyte target assay. We also studied the stimulatory effects of plasma collected from 3 patients with lethal septicemia caused by Streptococcus pneumoniae without detectable LPS but with 100-fold increased levels of heat-shock protein 70 (HSP70). HSP70 may, like LPS, activate monocytes via the Toll-like receptor 4 (TLR4). The samples were analyzed for LPS, tumor necrosis factor (TNF)-α, IL-10 and HSP70; applied on human monocytes (purity > 95%) before and after IL-10 immunodepletion, in the absence or presence of CD14 blocking mAb (60bca) or the lipid A antagonist, Rhodobacter sphaeroides diphosphoryl lipid A (RsDPLA) which blocks TLR4. Monocyte activation was measured by increased TNF-α secretion and tissue factor (TF) up-regulation by monocyte procoagulant activity (PCA). There was a positive correlation between patientplasma LPS levels ( n = 10) and increases in TNF-α secretion by the monocytes after immunodepletion of IL-10 ( r = 0.82). Pretreatment of the monocytes with mAbCD14 or RsDPLA reduced TNF-α secretion to median 5% and 12%, respectively, of the levels before the receptor complex was blocked. The median levels of HSP70 were 543 ng/ml (range, 468—962 ng/ml) in pneumococcal shock plasma, 81.5 ng/ml (range, 41—331 ng/ml) in meningococcal shock plasma and 24 ng/ml (range, < 0.8—41 ng/ml) in meningococcal non-shock plasma. Pneumococcal septic shock plasmas with significantly higher levels of HSP70 ( P < 0.05) did not induce TNF-α secretion in the monocytes. The results strongly suggest that LPS in meningococcal shock plasma is the major activator of monocytes whereas HSP70 (in plasma concentrations up to 963 ng/ml) does not activate monocytes in this assay.
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Affiliation(s)
- Anna Bjerre
- Department of Pediatrics, UllvÅl University Hospital, Oslo, Norway,
| | - Berit Brusletto
- The R&D Group, Department of Clinical Chemistry, UllevÅl University Hospital, Oslo, Norway
| | - Reidun Øvstebø
- The R&D Group, Department of Clinical Chemistry, UllevÅl University Hospital, Oslo, Norway
| | - Gun Britt Joø
- The R&D Group, Department of Clinical Chemistry, UllevÅl University Hospital, Oslo, Norway
| | - Peter Kierulf
- The R&D Group, Department of Clinical Chemistry, UllevÅl University Hospital, Oslo, Norway
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7
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Lipopolysaccharide-deficient Acinetobacter baumannii shows altered signaling through host Toll-like receptors and increased susceptibility to the host antimicrobial peptide LL-37. Infect Immun 2012; 81:684-9. [PMID: 23250952 DOI: 10.1128/iai.01362-12] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Infections caused by multidrug-resistant Acinetobacter baumannii have emerged as a serious global health problem. We have shown previously that A. baumannii can become resistant to the last-line antibiotic colistin via the loss of lipopolysaccharide (LPS), including the lipid A anchor, from the outer membrane (J. H. Moffatt, M. Harper, P. Harrison, J. D. Hale, E. Vinogradov, T. Seemann, R. Henry, B. Crane, F. St. Michael, A. D. Cox, B. Adler, R. L. Nation, J. Li, and J. D. Boyce, Antimicrob. Agents Chemother. 54:4971-4977, 2010). Here, we show how these LPS-deficient bacteria interact with components of the host innate immune system. LPS-deficient A. baumannii stimulated 2- to 4-fold lower levels of NF-κB activation and tumor necrosis factor alpha (TNF-α) secretion from immortalized murine macrophages, but it still elicited low levels of TNF-α secretion via a Toll-like receptor 2-dependent mechanism. Furthermore, we show that while LPS-deficient A. baumannii was not altered in its resistance to human serum, it showed increased susceptibility to the human antimicrobial peptide LL-37. Thus, LPS-deficient, colistin-resistant A. baumannii shows significantly altered activation of the host innate immune inflammatory response.
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8
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Geng D, Zheng L, Srivastava R, Velasco-Gonzalez C, Riker A, Markovic SN, Davila E. Amplifying TLR-MyD88 signals within tumor-specific T cells enhances antitumor activity to suboptimal levels of weakly immunogenic tumor antigens. Cancer Res 2010; 70:7442-54. [PMID: 20807806 DOI: 10.1158/0008-5472.can-10-0247] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The efficacy of T cell-based immunotherapy to treat cancer patients remains a challenge partly because of the weak activity toward subdominant tumor antigens (TAg) and to tumors expressing suboptimal TAg levels. Recent reports indicate that Toll-like receptor (TLR) stimulation on T cells can lower the activation threshold. In this study, we examined the antitumor activity and survival of TLR2-MyD88-stimulated CD8 T cells derived from melanoma patients and T-cell receptor transgenic pmel mice. TLR2-stimulated pmel CD8 T cells, but not TLR2(-/-)pmel or MyD88(-/-)pmel T cells, responded to significantly lower TAg levels and resulted in increased production of effector molecules and cytotoxicity. Wild-type or MyD88(-/-) mice treated with TLR2 ligand and pmel T cells, but not TLR2(-/-)pmel or MyD88(-/-)pmel T cells, showed tumor regression of an established melanoma tumor. Overexpressing TLR2 in TAg-specific T cells eradicated tumors; four times fewer cells were needed to generate antitumor responses. The enhanced antitumor activity of TLR2-MyD88-stimulated T cells was associated with increased effector function but perhaps more importantly with improved survival of T cells. Activating TLR-MyD88 signals in patient-derived T cells also reduced the activation threshold to several weakly immunogenic TAgs, resulting in increased cytokine production, expansion, and cytotoxicity. These data highlight a previously unappreciated role for activating TLR-MyD88 signals in tumor-reactive T lymphocytes.
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Affiliation(s)
- Degui Geng
- University of Maryland Greenebaum Cancer Center and Department of Otorhinolaryngology, Baltimore, Maryland 21201-1559, USA
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9
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When Toll-like receptor and T-cell receptor signals collide: a mechanism for enhanced CD8 T-cell effector function. Blood 2010; 116:3494-504. [PMID: 20696947 DOI: 10.1182/blood-2010-02-268169] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Emerging reports reveal that activating Toll-like receptor-2 (TLR2)-MyD88 signals in CD8 T lymphocytes enhances cytokine production and cytotoxicity; however, the signaling pathway remains undefined. In the present study, we examined the physiologic significance and molecular mechanisms involved in this process. We found that TLR2 engagement on T-cell receptor transgenic CD8 OT-1 T cells increased T-bet transcription factor levels consequently, augmenting effector transcript and protein levels both in vivo and in vitro. In contrast, TLR2 agonist did not costimulate TLR2(-/-)OT-1 or MyD88(-/-)OT-1 T cells. Elevated T-bet levels in TLR2-MyD88-activated T cells was a consequence of increased biosynthesis resulting from the enhanced activation of the mammalian target of the rapamycin (mTOR) pathway. Inhibiting mTOR, Akt, or protein kinase C in T cells abolished the costimulatory effects of the TLR2 agonist. In vivo, activating TLR2-MyD88 signals in T cells increased effector-molecule levels and enhanced the clearance of Listeria monocytogenes-Ova. These results help define a signaling pathway linking the TLR-MyD88 and mTOR pathway in an Akt- and protein kinase C-dependent manner. These results highlight a critical role for MyD88 signaling in T-cell activation and cytotoxicity. Furthermore, these findings offer the opportunity for improving the efficacy of vaccines and T cell-based immunotherapies by targeting TLR-MyD88 signaling within T cells.
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10
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Stages of meningococcal sepsis simulated in vitro, with emphasis on complement and Toll-like receptor activation. Infect Immun 2008; 76:4183-9. [PMID: 18591229 DOI: 10.1128/iai.00195-08] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The clinical presentation of meningococcal disease is closely related to the number of meningococci in the circulation. This study aimed to examine the activation of the innate immune system after being exposed to increasing and clinically relevant concentrations of meningococci. We incubated representative Neisseria meningitidis serogroup B (ST-32) and serogroup C (ST-11) strains and a lipopolysaccharide (LPS)-deficient mutant (the 44/76 lpxA mutant) in human serum and whole blood and measured complement activation and cytokine secretion and the effect of blocking these systems. HEK293 cells transfected with Toll-like receptors (TLRs) were examined for activation of NF-kappaB. The threshold for cytokine secretion and activation of NF-kappaB was 10(3) to 10(4) meningococci/ml. LPS was the sole inflammation-inducing molecule at concentrations up to 10(5) to 10(6) meningococci/ml. The activation was dependent on TLR4-MD2-CD14. Complement contributed to the inflammatory response at >or=10(5) to 10(6) meningococci/ml, and complement activation increased exponentially at >or=10(7) bacteria/ml. Non-LPS components initiated TLR2-mediated activation at >or=10(7) bacteria/ml. As the bacterial concentration exceeded 10(7)/ml, TLR4 and TLR2 were increasingly activated, independent of CD14. In this model mimicking human disease, the inflammatory response to N. meningitidis was closely associated with the bacterial concentration. Therapeutically, CD14 inhibition alone was most efficient at a low bacterial concentration, whereas addition of a complement inhibitor may be beneficial when the bacterial load increases.
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11
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Identification of genes particularly sensitive to lipopolysaccharide (LPS) in human monocytes induced by wild-type versus LPS-deficient Neisseria meningitidis strains. Infect Immun 2008; 76:2685-95. [PMID: 18362127 DOI: 10.1128/iai.01625-07] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Lipopolysaccharide (LPS) in the outer membrane of Neisseria meningitidis plays a dominant role as an inflammation-inducing molecule in meningococcal disease. We have used microarray analysis to study the global gene expression after exposure of human monocytes for 3 h to wild-type N. meningitidis (10(6)), LPS-deficient N. meningitidis (10(6) and 10(8)), and purified N. meningitidis LPS (1 ng [33 endotoxin units]/ml) to identify LPS-inducible genes. Wild-type N. meningitidis (10(6)) induced 4,689 differentially expressed genes, compared with 72 differentially expressed genes induced by 10(6) LPS-deficient N. meningitidis organisms. However, 10(8) LPS-deficient N. meningitidis organisms induced 3,905 genes, indicating a dose-response behavior of non-LPS cell wall molecules. A comparison of the gene expression patterns from 10(6) wild-type N. meningitidis and 10(8) LPS-deficient N. meningitidis organisms showed that 2,401 genes in human monocytes were not strictly LPS dependent. A list of "particularly LPS-sensitive" genes (2,288), differentially induced by 10(6) wild-type N. meningitidis but not by 10(8) LPS-deficient N. meningitidis organisms, showed an early expression of beta interferon (IFN-beta), most likely through the Toll-like receptor-MyD88-independent pathway. Subsequently, IFN-beta may activate the type I IFN signaling pathway, and an unknown number of IFN-beta-inducible genes, such as those for CXCL9, CXCL10, CXCL11, IFIT1, IFIT2, IFIT3, and IFIT5, are transcribed. Supporting this, human monocytes secreted significantly higher levels of CXCL10 and CXCL11 when stimulated by 10(6) wild-type N. meningitidis organisms than when stimulated by 10(8) LPS-deficient N. meningitidis organisms. Plasma CXCL10, but not CXCL11, was positively correlated (r = 0.67; P < 0.01) to LPS in patients (n = 24) with systemic meningococcal disease. Thus, new circulating biomarkers in meningococcal disease may be suggested through LPS-induced gene expression changes in human monocytes.
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12
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Mechanisms of dexamethasone-mediated inhibition of Toll-like receptor signaling induced by Neisseria meningitidis and Streptococcus pneumoniae. Infect Immun 2007; 76:189-97. [PMID: 17938219 DOI: 10.1128/iai.00856-07] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Excessive inflammation contributes to the pathogenesis of bacterial meningitis, which remains a serious disease despite treatment with antibiotics. Therefore, anti-inflammatory drugs have important therapeutic potential, and clinical trials have revealed that early treatment with dexamethasone significantly reduces mortality and morbidity from bacterial meningitis. Here we investigate the molecular mechanisms behind the inhibitory effect of dexamethasone upon the inflammatory responses evoked by Neisseria meningitidis and Streptococcus pneumoniae, two of the major causes of bacterial meningitis. The inflammatory cytokine response was dependent on Toll-like receptor signaling and was strongly inhibited by dexamethasone. Activation of the NF-kappaB pathway was targeted at several levels, including inhibition of IkappaB phosphorylation and NF-kappaB DNA-binding activity as well as upregulation of IkappaB alpha synthesis. Our data also revealed that the timing of steroid treatment relative to infection was important for achieving strong inhibition, particularly in response to S. pneumoniae. Altogether, we describe important targets of dexamethasone in the inflammatory responses evoked by N. meningitidis and S. pneumoniae, which may contribute to our understanding of the clinical effect and the importance of timing with respect to corticosteroid treatment during bacterial meningitis.
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13
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Fransen F, Boog CJ, van Putten JP, van der Ley P. Agonists of Toll-like receptors 3, 4, 7, and 9 are candidates for use as adjuvants in an outer membrane vaccine against Neisseria meningitidis serogroup B. Infect Immun 2007; 75:5939-46. [PMID: 17908810 PMCID: PMC2168345 DOI: 10.1128/iai.00846-07] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The bacterium Neisseria meningitidis is the causative agent of meningitis and sepsis. A generally effective vaccine against N. meningitidis serogroup B is not yet available, but outer membrane vesicle vaccines are in development. These vaccines contain lipopolysaccharide (LPS). The inclusion of N. meningitidis wild-type LPS in a vaccine is controversial because of its high toxicity. Therefore, the adjuvant activity of a panel of different Toll-like receptor (TLR) agonists in combination with LPS-deficient meningococcal outer membrane complexes was compared after immunization of mice. The results demonstrate that TLR3, TLR4, TLR7, and TLR9 agonists enhance immune responses against LPS-deficient outer membrane complexes. Their adjuvant activity was characterized by higher levels of antigen-specific immunoglobulin G (IgG), IgG2a, and IgG2b; a higher IgG2a/IgG1 ratio; lower total IgE levels; and most importantly, higher serum bactericidal antibody titers compared to LPS-deficient outer membrane complexes alone.
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Affiliation(s)
- Floris Fransen
- Laboratory for Vaccine Research, The Netherlands Vaccine Institute, Antonie van Leeuwenhoeklaan 11-13, 3720 AL Bilthoven, The Netherlands.
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Plant L, Wan H, Jonsson AB. MyD88-dependent signaling affects the development of meningococcal sepsis by nonlipooligosaccharide ligands. Infect Immun 2006; 74:3538-46. [PMID: 16714586 PMCID: PMC1479290 DOI: 10.1128/iai.00128-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Toll-like receptors (TLRs) and the adaptor myeloid differentiation factor 88 (MyD88) are important in the innate immune defenses of the host to microbial infections. Meningococcal ligands signaling via TLRs control inflammatory responses, and stimulation can result in fulminant meningococcal sepsis. In this study, we show that the responses to nonlipooligosaccharide (non-LOS) ligands of meningococci are MyD88 dependent. An isogenic LOS-deficient mutant of the serogroup C meningococcal strain FAM20 caused fatal disease in wild type C57BL/6 mice that was not observed in MyD88-/- mice. Fatality correlated with high proinflammatory cytokine and C5a levels in serum, high neutrophil numbers in blood, and increased bacteremia at 24 h postinfection in the wild-type mice. Infection with the parent strain FAM20 resulted in fatality in 100% of the wild-type mice and 50% of the MyD88-/- mice. We conclude that both LOS and another neisserial ligand cause meningococcal sepsis in an in vivo mouse model and confirm that meningococcal LOS can act via both the MyD88- dependent and -independent pathways, while the non-LOS meningococcal ligand(s) acts only via the MyD88-dependent pathway.
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Affiliation(s)
- Laura Plant
- Department of Medical Biochemistry and Microbiology, Biomedical Centrum, Uppsala University, 751 23 Uppsala, Sweden.
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15
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Uronen-Hansson H, Allen J, Osman M, Squires G, Klein N, Callard RE. Toll-like receptor 2 (TLR2) and TLR4 are present inside human dendritic cells, associated with microtubules and the Golgi apparatus but are not detectable on the cell surface: integrity of microtubules is required for interleukin-12 production in response to internalized bacteria. Immunology 2004; 111:173-8. [PMID: 15027902 PMCID: PMC1782406 DOI: 10.1111/j.0019-2805.2003.01803.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The activation of dendritic cells (DCs) by microbes is mediated by pattern recognition receptors including the Toll-like receptors (TLR). Bacterial lipopolysaccharide acts via TLR4 whereas peptidoglycan and lipoprotein responses are mediated by TLR2. It is generally accepted that TLR binding to microbes occurs at the cell surface but this has not been directly demonstrated for human DCs. We show here that TLR2 and TLR4 are expressed inside DCs in an abundant tubulovesicular pattern with a focus of intense staining adjacent to the nucleus. In contrast, there was no detectable expression on the cell surface. TLR2 and TLR4 were readily found both intracellularly and on the surface of monocytes. They were shown to be closely associated with the Golgi complex and colocalized with alpha-tubulin, displaying a high focal concentration at the microtubule organizing centre. Alignment of TLR2 and TLR4 with microtubules was observed, suggesting that microtubules serve as transport tracks for TLR vesicles. Depolymerization of the microtubule network disrupted the intracellular expression of TLR2 and TLR4 and profoundly inhibited interleukin-12 (IL-12) production in response to Neisseria meningitidis but did not prevent phagocytosis. These data are consistent with the bacterial signalling through TLR2 and TLR4 required for IL-12 production occurring inside DCs after phagocytosis.
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Al-Bader T, Christodoulides M, Heckels JE, Holloway J, Semper AE, Friedmann PS. Activation of human dendritic cells is modulated by components of the outer membranes of Neisseria meningitidis. Infect Immun 2003; 71:5590-7. [PMID: 14500478 PMCID: PMC201071 DOI: 10.1128/iai.71.10.5590-5597.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Neisseria meningitidis serogroup B is a major cause of life-threatening meningitis and septicemia worldwide, and no effective vaccine is available. Initiation of innate and acquired immune responses to N. meningitidis is likely to be dependent on cellular responses of dendritic cells (DC) to antigens present in the outer membrane (OM) of the meningococcus. In this study, the responses of human monocyte-derived DC (mo-DC) to OM isolated from parent (lipopolysaccharide [LPS]-replete) meningococci and from a mutant deficient in LPS were investigated. Parent OM selectively up-regulated Toll-like receptor 4 (TLR4) mRNA expression and induced mo-DC maturation, as reflected by increased production of chemokines, proinflammatory cytokines, and CD83, CD80, CD86, CD40, and major histocompatibility complex (MHC) class II molecules. In contrast, LPS-deficient OM selectively up-regulated TLR2 mRNA expression and induced moderate increases in both cytokine production and expression of CD86 and MHC class II molecules. Preexposure to OM, with or without LPS, augmented the allostimulatory properties of mo-DC, which induced proliferation of naive CD4+ CD45RA+ T cells. In addition, LPS-replete OM induced a greater gamma interferon/interleukin-13 ratio in naive T cells, whereas LPS-deficient OM induced the reverse profile. These data demonstrate that components of the OM, other than LPS, are also likely to be involved in determining the levels of DC activation and the nature of the T-helper immune response.
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Affiliation(s)
- Tamara Al-Bader
- Dermatopharmacology Unit, Southampton General Hospital, Southampton SO16 6YD, United Kingdom
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