Important Role for Toll-Like Receptor 9 in Host Defense against Meningococcal Sepsis

ABSTRACT Neisseria meningitidis is a leading cause of meningitis and sepsis. The pathogenesis of meningococcal disease is determined by both bacterial virulence factors and the host inflammatory response. Toll-like receptors (TLRs) are prominent activators of the inflammatory response, and TLR2, -4, and -9 have been reported to be involved in the host response to N. meningitidis. While TLR4 has been suggested to play an important role in early containment of infection, the roles of TLR2 and TLR9 in meningococcal disease are not well described. Using a model for meningococcal sepsis, we report that TLR9−/− mice displayed reduced survival and elevated levels of bacteremia compared to wild-type mice. In contrast, TLR2−/− mice controlled the infection in a manner comparable to that of wild-type mice. TLR9 deficiency was also associated with reduced bactericidal activity in vitro, which was accompanied by reduced production of nitric oxide by TLR9-deficient macrophages. Interestingly, TLR9−/− mice recruited more macrophages to the bloodstream than wild-type mice and produced elevated levels of cytokines at late time points during infection. At the cellular level, activation of signal transduction and induction of cytokine gene expression were independent of TLR2 or TLR9 in macrophages and conventional dendritic cells. In contrast, plasmacytoid dendritic cells relied entirely on TLR9 to induce these activities. Thus, our data demonstrate an important role for TLR9 in host defense against N. meningitidis.

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Effects of Staphylococcus aureus Bacteriophage K on Expression of Cytokines and Activation Markers by Human Dendritic Cells In Vitro

Viruses ◽

10.3390/v10110617 ◽

2018 ◽

Vol 10 (11) ◽

pp. 617 ◽

Cited By ~ 5

Author(s):

Helen Freyberger ◽

Yunxiu He ◽

Amanda Roth ◽

Mikeljon Nikolich ◽

Andrey Filippov

Keyword(s):

Staphylococcus Aureus ◽

Dendritic Cells ◽

Inflammatory Response ◽

Adaptive Immune Response ◽

Human Monocyte ◽

Activation Markers ◽

Mhc I ◽

Adaptive Immune ◽

Human Dendritic Cells

A potential concern with bacteriophage (phage) therapeutics is a host-versus-phage response in which the immune system may neutralize or destroy phage particles and thus impair therapeutic efficacy, or a strong inflammatory response to repeated phage exposure might endanger the patient. Current literature is discrepant with regard to the nature and magnitude of innate and adaptive immune response to phages. The purpose of this work was to study the potential effects of Staphylococcus aureus phage K on the activation of human monocyte-derived dendritic cells. Since phage K acquired from ATCC was isolated around 90 years ago, we first tested its activity against a panel of 36 diverse S. aureus clinical isolates from military patients and found that it was lytic against 30/36 (83%) of strains. Human monocyte-derived dendritic cells were used to test for an in vitro phage-specific inflammatory response. Repeated experiments demonstrated that phage K had little impact on the expression of pro- and anti-inflammatory cytokines, or on MHC-I/II and CD80/CD86 protein expression. Given that dendritic cells are potent antigen-presenting cells and messengers between the innate and the adaptive immune systems, our results suggest that phage K does not independently affect cellular immunity or has a very limited impact on it.

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Impaired functional activity of alveolar macrophages from GM-CSF-deficient mice

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.2001.281.5.l1210 ◽

2001 ◽

Vol 281 (5) ◽

pp. L1210-L1218 ◽

Cited By ~ 56

Author(s):

Robert Paine ◽

Susan B. Morris ◽

Hong Jin ◽

Steven E. Wilcoxen ◽

Susan M. Phare ◽

...

Keyword(s):

Host Defense ◽

Alveolar Macrophages ◽

Phagocytic Activity ◽

Wild Type ◽

Specific Expression ◽

Gm Csf ◽

Functional Capabilities ◽

Tnf Α

We hypothesized that pulmonary granulocyte-macrophage colony-stimulating factor (GM-CSF) is critically involved in determining the functional capabilities of alveolar macrophages (AM) for host defense. To test this hypothesis, cells were collected by lung lavage from GM-CSF mutant mice [GM(−/−)] and C57BL/6 wild-type mice. GM(−/−) mice yielded almost 4-fold more AM than wild-type mice. The percentage of cells positive for the β2-integrins CD11a and CD11c was reduced significantly in GM(−/−) AM compared with wild-type cells, whereas expression of CD11b was similar in the two groups. The phagocytic activity of GM(−/−) AM for FITC-labeled microspheres was impaired significantly compared with that of wild-type AM both in vitro and in vivo (after intratracheal inoculation with FITC-labeled beads). Stimulated secretion of tumor necrosis factor-α (TNF-α) and leukotrienes by AM from the GM(−/−) mice was greatly reduced compared with wild-type AM, whereas secretion of monocyte chemoattractant protein-1 was increased. Transgenic expression of GM-CSF exclusively in the lungs of GM(−/−) mice resulted in AM with normal or supranormal expression of CD11a and CD11c, phagocytic activity, and TNF-α secretion. Thus, in the absence of GM-CSF, AM functional capabilities for host defense were significantly impaired but were restored by lung-specific expression of GM-CSF.

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The Decreased Replicative Capacity of Simian Immunodeficiency Virus SIVmac239Δnef Is Manifest in Cultures of Immature Dendritic Cells and T Cells

Journal of Virology ◽

10.1128/jvi.74.5.2406-2413.2000 ◽

2000 ◽

Vol 74 (5) ◽

pp. 2406-2413 ◽

Cited By ~ 49

Author(s):

Davorka Messmer ◽

Ralf Ignatius ◽

Christine Santisteban ◽

Ralph M. Steinman ◽

Melissa Pope

Keyword(s):

T Cells ◽

Dendritic Cells ◽

T Cell ◽

Simian Immunodeficiency Virus ◽

Culture System ◽

Wild Type ◽

Virus Dose ◽

Immunodeficiency Virus

ABSTRACT Transmission of simian immunodeficiency virus SIVmac239Δnef (Δnef) to macaques results in attenuated replication of the virus in most animals and ultimately induces protection against challenge with some pathogenic, wild-type SIV strains. It has been difficult, however, to identify a culture system in which the replication of Δnef is severely reduced relative to that of the wild type. We have utilized a primary culture system consisting of blood-derived dendritic cells (DCs) and autologous T cells. When the DCs were fully differentiated or mature, the DC–CD4+ T-cell mixtures supported replication of both the parental SIV strain, 239 (the wild type), and its mutant withnef deleted (Δnef), irrespective of virus dose and the cell type introducing the virus to the coculture. In contrast, when immature DCs were exposed to Δnef and cocultured with T cells, virus replication was significantly lower than that of the wild type. Activation of the cultures with a superantigen allowed both Δnef and the wild type to replicate comparably in immature DC–T-cell cultures. Immature DCs, which, it has been hypothesized, capture and transmit SIV in vivo, are deficient in supporting replication of Δnef in vitro and may contribute to the reduced pathogenicity of Δnef in vivo.

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Interleukin-23 (IL-23)-IL-17 Cytokine Axis in Murine Pneumocystis carinii Infection

Infection and Immunity ◽

10.1128/iai.01329-06 ◽

2007 ◽

Vol 75 (6) ◽

pp. 3055-3061 ◽

Cited By ~ 182

Author(s):

Xiaowen L. Rudner ◽

Kyle I. Happel ◽

Erana A. Young ◽

Judd E. Shellito

Keyword(s):

T Cells ◽

Host Defense ◽

Defense Mechanisms ◽

Pneumocystis Carinii ◽

Neutralizing Antibody ◽

Wild Type ◽

Pneumocystis Carinii Infection ◽

Interleukin 23

ABSTRACT Host defense mechanisms against Pneumocystis carinii are not fully understood. Previous work in the murine model has shown that host defense against infection is critically dependent upon host CD4+ T cells. The recently described Th17 immune response is predominantly a function of effector CD4+ T cells stimulated by interleukin-23 (IL-23), but whether these cells are required for defense against P. carinii infection is unknown. We tested the hypothesis that P. carinii stimulates the early release of IL-23, leading to increases in IL-17 production and lung effector CD4+ T-cell population that mediate clearance of infection. In vitro, stimulation of alveolar macrophages with P. carinii induced IL-23, and IL-23p19 mRNA was expressed in lungs of mice infected with this pathogen. To address the role of IL-23 in resistance to P. carinii, IL-23p19−/− and wild-type control C57BL/6 mice were infected and their fungal burdens and cytokine/chemokine responses were compared. IL-23p19−/− mice displayed transient but impaired clearance of infection, which was most apparent 2 weeks after inoculation. In confirmatory studies, the administration of either anti-IL-23p19 or anti-IL-17 neutralizing antibody to wild-type mice infected with P. carinii also caused increases in fungal burdens. IL-17 and the lymphocyte chemokines IP-10, MIG, MIP-1α, MIP-1β, and RANTES were decreased in the lungs of infected IL-23p19−/− mice in comparison to their levels in the lungs of wild-type mice. In IL-23p19−/− mice infected with P. carinii, there were fewer effector CD4+ T cells in the lung tissue. Collectively, these studies indicate that the IL-23-IL-17 axis participates in host defense against P. carinii.

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Phenotypic Characterization of Auxotrophic Mutant of Nontyphoidal Salmonella and Determination of Its Cytotoxicity, Tumor Inhibiting Cytokine Gene Expression in Cell Line Models

10.21203/rs.3.rs-170220/v1 ◽

2021 ◽

Author(s):

Kadeeja Jazeela ◽

Anirban Chakraborty ◽

Akshatha Kotian ◽

Vankadari Aditya ◽

Krishna Kumar Ballamoole ◽

...

Keyword(s):

Cell Line ◽

Cell Lines ◽

Type Strain ◽

Virulence Genes ◽

Wild Type Strain ◽

Auxotrophic Mutant ◽

Cytokine Gene Expression ◽

Wild Type ◽

Cytokine Genes

Abstract An auxotrophic mutant of non-typhoidal Salmonella (NTS) strain was phenotypically characterized in this study. The characterization was based on phenotype, morphology, motility, biofilm forming ability, growth kinetics, etc. The phenotypic results from the above experiments determined that the mutant showed variation in phenotypic characters from that of wild-type strain. Subsequently, mutant and wild-type NTS were subjected to epithelial cell invasion and intracellular replication assays. The real time PCR analysis was also performed to analyse expression of tumor inhibiting cytokine genes and virulence genes post bacterial infection in cell lines. The mutant showed highest invasion potential than wild-type NTS whereas the replication of mutant was slower in both the cell lines. Similar to the wild-type strain, the mutant also retained the cytotoxic potential when analysed in vitro. Furthermore, the expression of proinflammatory cytokine genes such as TNF-α and IL-1β was upsurged with the downregulation of anti-inflammatory cytokine genes like TGF-β, IL-6 and IL-10 post infection of the mutant strain in cell lines. In addition, virulence genes of Salmonella pathogenicity island one and two of mutant were downregulated in vitro except invA in HeLa cell line. Therefore, the auxotrophic mutant showed positive attributes of a potential antitumor agent in terms of expressing tumor inhibiting cytokine genes when assessed in vitro. Though the study did not check the tumor inhibitory effect of NTS strain directly, findings of the study emphasizes on the development of a novel strain of NTS with less virulence and more immunogenic traits to inhibit tumor cells.

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Ficolins Promote Fungal Clearance in vivo and Modulate the Inflammatory Cytokine Response in Host Defense against Aspergillus fumigatus

Journal of Innate Immunity ◽

10.1159/000447714 ◽

2016 ◽

Vol 8 (6) ◽

pp. 579-588 ◽

Cited By ~ 17

Author(s):

Ninette Genster ◽

Elisabeth Præstekjær Cramer ◽

Anne Rosbjerg ◽

Katrine Pilely ◽

Jack Bernard Cowland ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Host Defense ◽

Knockout Mice ◽

Fungal Infections ◽

Inflammatory Cells ◽

Lectin Pathway ◽

Wild Type ◽

Opportunistic Fungal Pathogen

Aspergillus fumigatus is an opportunistic fungal pathogen that causes severe invasive infections in immunocompromised patients. Innate immunity plays a major role in protection against A. fumigatus. The ficolins are a family of soluble pattern recognition receptors that are capable of activating the lectin pathway of complement. Previous in vitro studies reported that ficolins bind to A. fumigatus, but their part in host defense against fungal infections in vivo is unknown. In this study, we used ficolin-deficient mice to investigate the role of ficolins during lung infection with A. fumigatus. Ficolin knockout mice showed significantly higher fungal loads in the lungs 24 h postinfection compared to wild-type mice. The delayed clearance of A. fumigatus in ficolin knockout mice could not be attributed to a compromised recruitment of inflammatory cells. However, it was revealed that ficolin knockout mice exhibited a decreased production of proinflammatory cytokines in the lungs compared to wild-type mice following A. fumigatus infection. The impaired clearance and cytokine production in ficolin knockout mice was independent of complement, as shown by equivalent levels of A. fumigatus-mediated complement activation in ficolin knockout mice and wild-type mice. In conclusion, this study demonstrates that ficolins are important in initial innate host defense against A. fumigatus infections in vivo.

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Complement C5a Receptor 1 Exacerbates the Pathophysiology of N. meningitidis Sepsis and Is a Potential Target for Disease Treatment

mBio ◽

10.1128/mbio.01755-17 ◽

2018 ◽

Vol 9 (1) ◽

Cited By ~ 13

Author(s):

Johannes B. Herrmann ◽

Marcel Muenstermann ◽

Lea Strobel ◽

Alexandra Schubert-Unkmeir ◽

Trent M. Woodruff ◽

...

Keyword(s):

Inflammatory Response ◽

Meningococcal Disease ◽

Whole Blood ◽

Membrane Attack Complex ◽

Invasive Meningococcal Disease ◽

Medical Attention ◽

Complement Cascade ◽

Meningococcal Sepsis ◽

C5a Receptor ◽

Initial Symptoms

ABSTRACTSepsis caused byNeisseria meningitidis(meningococcus) is a rapidly progressing, life-threatening disease. Because its initial symptoms are rather unspecific, medical attention is often sought too late, i.e., when the systemic inflammatory response is already unleashed. This in turn limits the success of antibiotic treatment. The complement system is generally accepted as the most important innate immune determinant against invasive meningococcal disease since it protects the host through the bactericidal membrane attack complex. However, complement activation concomitantly liberates the C5a peptide, and it remains unclear whether this potent anaphylatoxin contributes to protection and/or drives the rapidly progressing immunopathogenesis associated with meningococcal disease. Here, we dissected the specific contribution of C5a receptor 1 (C5aR1), the canonical receptor for C5a, using a mouse model of meningococcal sepsis. Mice lacking C3 or C5 displayed susceptibility that was enhanced by >1,000-fold or 100-fold, respectively, consistent with the contribution of these components to protection. In clear contrast,C5ar1−/−mice resisted invasive meningococcal infection and clearedN. meningitidismore rapidly than wild-type (WT) animals. This favorable outcome stemmed from an ameliorated inflammatory cytokine response toN. meningitidisinC5ar1−/−mice in bothin vivoandex vivowhole-blood infections. In addition, inhibition of C5aR1 signaling without interference with the complement bactericidal activity reduced the inflammatory response also in human whole blood. Enticingly, pharmacologic C5aR1 blockade enhanced mouse survival and lowered meningococcal burden even when the treatment was administered after sepsis induction. Together, our findings demonstrate that C5aR1 drives the pathophysiology associated with meningococcal sepsis and provides a promising target for adjunctive therapy.IMPORTANCEThe devastating consequences ofN. meningitidissepsis arise due to the rapidly arising and self-propagating inflammatory response that mobilizes antibacterial defenses but also drives the immunopathology associated with meningococcemia. The complement cascade provides innate broad-spectrum protection against infection by directly damaging the envelope of pathogenic microbes through the membrane attack complex and triggers an inflammatory response via the C5a peptide and its receptor C5aR1 aimed at mobilizing cellular effectors of immunity. Here, we consider the potential of separating the bactericidal activities of the complement cascade from its immune activating function to improve outcome ofN. meningitidissepsis. Our findings demonstrate that the specific genetic or pharmacological disruption of C5aR1 rapidly ameliorates disease by suppressing the pathogenic inflammatory response and, surprisingly, allows faster clearance of the bacterial infection. This outcome provides a clear demonstration of the therapeutic benefit of the use of C5aR1-specific inhibitors to improve the outcome of invasive meningococcal disease.

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Salmonella-Induced Cell Death Is Not Required for Enteritis in Calves

Infection and Immunity ◽

10.1128/iai.69.7.4610-4617.2001 ◽

2001 ◽

Vol 69 (7) ◽

pp. 4610-4617 ◽

Cited By ~ 52

Author(s):

Renato L. Santos ◽

Renée M. Tsolis ◽

Shuping Zhang ◽

Thomas A. Ficht ◽

Andreas J. Bäumler ◽

...

Keyword(s):

Cell Death ◽

Inflammatory Response ◽

Fluid Secretion ◽

Luria Bertani ◽

Wild Type ◽

Fluid Accumulation ◽

Luria Bertani Broth ◽

Serovar Typhimurium ◽

In The Wild

ABSTRACT Salmonella enterica serovar Typhimurium causes cell death in bovine monocyte-derived and murine macrophages in vitro by asipB-dependent mechanism. During this process, SipB binds and activates caspase-1, which in turn activates the proinflammatory cytokine interleukin-1β through cleavage. We used bovine ileal ligated loops to address the role of serovar Typhimurium-induced cell death in induction of fluid accumulation and inflammation in this diarrhea model. Twelve perinatal calves had 6- to 9-cm loops prepared in the terminal ileum. They were divided into three groups: one group received an intralumen injection of Luria-Bertani broth as a control in 12 loops. The other two groups (four calves each) were inoculated with 0.75 × 109 CFU of either wild-type serovar Typhimurium (strain IR715) or a sopB mutant per loop in 12 loops. Hematoxylin and eosin-stained sections were scored for inflammation, and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells were detected in situ. Fluid accumulation began at 3 h postinfection (PI). Inflammation was detected in all infected loops at 1 h PI. The area of TUNEL-labeled cells in the wild-type infected loops was significantly higher than that of the controls at 12 h PI, when a severe inflammatory response and tissue damage had already developed. ThesopB mutant induced the same amount of TUNEL-positive cells as the wild type, but it was attenuated for induction of fluid secretion and inflammation. Our results indicate that serovar Typhimurium-induced cell death is not required to trigger an early inflammatory response and fluid accumulation in the ileum.

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Use of interleukin 7 receptor-α knockout donor cells demonstrates the lymphoid independence of dendritic cells

Blood ◽

10.1182/blood-2005-02-0647 ◽

2006 ◽

Vol 107 (1) ◽

pp. 184-186 ◽

Cited By ~ 9

Author(s):

Satoshi Takeuchi ◽

Stephen I. Katz

Keyword(s):

Dendritic Cells ◽

Nk Cells ◽

Natural Killer ◽

Langerhans Cells ◽

Wild Type ◽

Lymphoid Lineage ◽

Interleukin 7 ◽

Donor Cells

Abstract The precise lineage of dendritic cells (DCs), including skin Langerhans cells (LCs), is unclear. Interleukin 7 (IL-7) and its receptor (IL-7Rα) are known to mediate lymphopoiesis, and IL-7 is also known to be essential for the generation of DCs from lymphoid-committed precursors in vitro. Thus, to determine the developmental lymphoid (or IL-7Rα) dependency of various DCs and to examine the importance of IL-7/IL-7Rα for DC development in vivo, we used IL-7Rα knockout (KO) donor cells to reconstitute DCs/LCs in sublethally irradiated recipients and compared the results to those obtained using wild-type (WT) donor cells. We found that lymphoid lineage cells (except natural killer [NK] cells), including thymocytes, were less efficiently reconstituted by IL-7Rα KO donor cells, whereas myeloid lineage cells and DCs/LCs were equally well reconstituted by both the IL-7Rα KO and WT donor cells. Overall, we conclude that IL-7Rα is not required for the development of DCs/LC in vivo.

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Identification of Two Subsets of Murine DC1 Dendritic Cells That Differ by Surface Phenotype, Gene Expression, and Function

Frontiers in Immunology ◽

10.3389/fimmu.2021.746469 ◽

2021 ◽

Vol 12 ◽

Author(s):

David Hongo ◽

Pingping Zheng ◽

Suparna Dutt ◽

Rahul Pawar ◽

Everett Meyer ◽

...

Keyword(s):

Gene Expression ◽

Dendritic Cells ◽

Wild Type ◽

Surface Receptors ◽

Cytokine Responses ◽

Th1 Cytokine ◽

And Function ◽

Functional Profiles

Classical dendritic cells (cDCs) in mice have been divided into 2 major subsets based on the expression of nuclear transcription factors: a CD8+Irf8+Batf3 dependent (DC1) subset, and a CD8-Irf4+ (DC2) subset. We found that the CD8+DC1 subset can be further divided into CD8+DC1a and CD8+DC1b subsets by differences in surface receptors, gene expression, and function. Whereas all 3 DC subsets can act alone to induce potent Th1 cytokine responses to class I and II MHC restricted peptides derived from ovalbumin (OVA) by OT-I and OT-II transgenic T cells, only the DC1b subset could effectively present glycolipid antigens to natural killer T (NKT) cells. Vaccination with OVA protein pulsed DC1b and DC2 cells were more effective in reducing the growth of the B16-OVA melanoma as compared to pulsed DC1a cells in wild type mice. In conclusion, the Batf3-/- dependent DC1 cells can be further divided into two subsets with different immune functional profiles in vitro and in vivo.

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