scholarly journals MyD88-Dependent Responses Involving Toll-Like Receptor 2 Are Important for Protection and Clearance of Legionella pneumophila in a Mouse Model of Legionnaires' Disease

2006 ◽  
Vol 74 (6) ◽  
pp. 3325-3333 ◽  
Author(s):  
Kristina A. Archer ◽  
Craig R. Roy
Keyword(s):  
Pattern Recognition ◽  
Bacterial Growth ◽  
Legionella Pneumophila ◽  
Ex Vivo ◽  
Innate Immune ◽  
Toll Like Receptor ◽  
Littermate Control ◽  
Legionnaires Disease ◽  
Deficient Mice

ABSTRACT Legionella pneumophila is a gram-negative facultative intracellular parasite of macrophages. Although L. pneumophila is the causative agent of a severe pneumonia known as Legionnaires' disease, it is likely that most infections caused by this organism are cleared by the host innate immune system. It is predicted that host pattern recognition proteins belonging to the Toll-like receptor (TLR) family are involved in the protective innate immune responses. We examined the role of TLR-mediated responses in L. pneumophila detection and clearance using genetically altered mouse hosts in which the macrophages are permissive for L. pneumophila intracellular replication. Our data demonstrate that cytokine production by bone marrow-derived macrophages (BMMs) in response to L. pneumophila infection requires the TLR adapter protein MyD88 and is reduced in the absence of TLR2 but not in the absence of TLR4. Bacterial growth ex vivo in BMMs from MyD88-deficient mice was not enhanced compared to bacterial growth ex vivo in BMMs from heterozygous littermate controls. Wild-type mice were able to clear L. pneumophila from the lung, whereas respiratory infection of MyD88-deficient mice caused death that resulted from robust bacterial replication and dissemination. In contrast to an infection with virulent L. pneumophila, MyD88-deficient mice were able to clear infections with L. pneumophila dotA mutants, indicating that MyD88-independent responses in the lung are sufficient to clear bacteria that are unable to replicate intracellularly. In vivo growth of L. pneumophila was enhanced in the lungs of TLR2-deficient mice, which resulted in a delay in bacterial clearance. No significant differences were observed in the growth and clearance of L. pneumophila in the lungs of TLR4-deficient mice and heterozygous littermate control mice. Our data indicate that MyD88 is crucial for eliciting a protective innate immune response against virulent L. pneumophila and that TLR2 is one of the pattern recognition receptors involved in initiating this MyD88-dependent response.

scholarly journals Cooperation between Multiple Microbial Pattern Recognition Systems Is Important for Host Protection against the Intracellular Pathogen Legionella pneumophila

2010 ◽  
Vol 78 (6) ◽  
pp. 2477-2487 ◽  
Author(s):  
Kristina A. Archer ◽  
Florence Ader ◽  
Koichi S. Kobayashi ◽  
Richard A. Flavell ◽  
Craig R. Roy
Keyword(s):  
Pattern Recognition ◽  
Legionella Pneumophila ◽  
Innate Immune ◽  
Intracellular Pathogen ◽  
Innate Immune Responses ◽  
Host Protection ◽  
Lethal Infection ◽  
Pattern Recognition Systems ◽  
Recognition Systems ◽  
Deficient Mice

ABSTRACT Multiple pattern recognition systems have been shown to initiate innate immune responses to microbial pathogens. The degree to which these detection systems cooperate with each other to provide host protection is unknown. Here, we investigated the importance of several immune surveillance pathways in protecting mice against lethal infection by the intracellular pathogen Legionella pneumophila, the causative agent of a severe pneumonia called Legionnaires' disease. Rip2 and Naip5/NLRC4 signaling was found to contribute to the innate immune response generated against L. pneumophila in the lung. Elimination of Rip2 or Naip5/NLRC4 signaling in MyD88-deficient mice resulted in increased replication and dissemination of L. pneumophila and higher rates of mortality. Irradiated wild-type mice receiving bone marrow cells from pattern recognition receptor-deficient mice displayed L. pneumophila infection phenotypes similar to those of donor mice. Rip2 and Naip5/NLRC4 signaling provided additive effects in protecting MyD88-deficient mice from lethal infection by L. pneumophila, with the contribution of Naip5/NLRC4 being slightly greater than that of Rip2. Thus, activation of the Rip2, MyD88, and Naip5/NLRC4 signaling pathways triggers a coordinated and synergistic response that protects the host against lethal infection by L. pneumophila. These data provide new insight into how different pattern recognition systems interact functionally to generate innate immune responses that protect the host from lethal infection by activating cellular pathways that restrict intracellular replication of L. pneumophila and by recruiting to the site of infection additional phagocytes that eliminate extracellular bacteria.

scholarly journals Overlapping Roles for Interleukin-36 Cytokines in Protective Host Defense against MurineLegionella pneumophilaPneumonia

2018 ◽  
Vol 87 (1) ◽  
Author(s):  
Yuta Nanjo ◽  
Michael W. Newstead ◽  
Tetsuji Aoyagi ◽  
Xianying Zeng ◽  
Kazuhisa Takahashi ◽  
...  
Keyword(s):  
Host Defense ◽  
Legionella Pneumophila ◽  
Ex Vivo ◽  
Inflammatory Cells ◽  
Bacterial Clearance ◽  
Content Type ◽  
Cytokines And Chemokines ◽  
M1 Polarization ◽  
Life Threatening ◽  
Deficient Mice

ABSTRACTLegionella pneumophilacauses life-threatening pneumonia culminating in acute lung injury. Innate and adaptive cytokines play an important role in host defense againstL. pneumophilainfection. Interleukin-36 (IL-36) cytokines are recently described members of the larger IL-1 cytokine family known to exert potent inflammatory effects. In this study, we elucidated the role for IL-36 cytokines in experimental pneumonia caused byL. pneumophila. Intratracheal (i.t.) administration ofL. pneumophilainduced the upregulation of both IL-36α and IL-36γ mRNA and protein production in the lung. Compared to the findings forL. pneumophila-infected wild-type (WT) mice, the i.t. administration ofL. pneumophilato IL-36 receptor-deficient (IL-36R−/−) mice resulted in increased mortality, a delay in lung bacterial clearance, increasedL. pneumophiladissemination to extrapulmonary organs, and impaired glucose homeostasis. Impaired lung bacterial clearance in IL-36R−/−mice was associated with a significantly reduced accumulation of inflammatory cells and the decreased production of proinflammatory cytokines and chemokines.Ex vivo, reduced expression of costimulatory molecules and impaired M1 polarization were observed in alveolar macrophages isolated from infected IL-36R−/−mice compared to macrophages from WT mice. WhileL. pneumophila-induced mortality in IL-36α- or IL-36γ-deficient mice was not different from that in WT animals, antibody-mediated neutralization of IL-36γ in IL-36α−/−mice resulted in mortality similar to that observed in IL-36R−/−mice, indicating redundant and overlapping roles for these cytokines in experimental murineL. pneumophilapneumonia.

scholarly journals Induction of Interleukin-4 (IL-4) by Legionella pneumophila Infection in BALB/c Mice and Regulation of Tumor Necrosis Factor Alpha, IL-6, and IL-1β

2000 ◽  
Vol 68 (9) ◽  
pp. 5234-5240 ◽  
Author(s):  
Catherine Newton ◽  
Shannon McHugh ◽  
Ray Widen ◽  
Noriya Nakachi ◽  
Thomas Klein ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis Factor Alpha ◽  
Legionella Pneumophila ◽  
Tumor Necrosis ◽  
Ex Vivo ◽  
Necrosis Factor Alpha ◽  
Tnf Α ◽  
Factor Alpha ◽  
Deficient Mice ◽  
Necrosis Factor

ABSTRACT Infection of BALB/c mice with a sublethal concentration ofLegionella pneumophila causes an acute disease that is resolved by innate immune responses. The infection also initiates the development of adaptive Th1 responses that protect the mice from challenge infections. To study the early responses, cytokines induced during the first 24 h after infection were examined. In the serum, interleukin-12 (IL-12) was detectable by 3 h and peaked at 10 h, while gamma interferon was discernible by 5 h and peaked at 8 h. Similar patterns were observed in ex vivo cultures of splenocytes. A transient IL-4 response was also detected by 3 h postinfection in ex vivo cultures. BALB/c IL-4-deficient mice were more susceptible to L. pneumophila infection than were wild-type mice. The infection induced higher serum levels of acute-phase cytokines (tumor necrosis factor alpha [TNF-α], IL-1β, and IL-6), and reducing TNF-α levels with antibodies protected the mice from death. Moreover, the addition of IL-4 to L. pneumophila-infected macrophage cultures suppressed the production of these cytokines. Thus, the lack of IL-4 in the deficient mice resulted in unchecked TNF-α production, which appeared to cause the mortality. Monocyte chemoattractant protein-1 (MCP-1), a chemokine that is induced by IL-4 during Listeria monocytogenesinfection, was detected at between 2 and 30 h after infection. However, MCP-1 did not appear to be induced by IL-4 or to be required for the TNF-α regulation by IL-4. The data suggest that the early increase in IL-4 serves to regulate the mobilization of acute phase cytokines and thus controls the potential harmful effects of these cytokines.

scholarly journals Toll-like receptor 9 controls anti-DNA autoantibody production in murine lupus

2005 ◽  
Vol 202 (2) ◽  
pp. 321-331 ◽  
Author(s):  
Sean R. Christensen ◽  
Michael Kashgarian ◽  
Lena Alexopoulou ◽  
Richard A. Flavell ◽  
Shizuo Akira ◽  
...  
Keyword(s):  
Autoimmune Disease ◽  
Lupus Erythematosus ◽  
Critical Role ◽  
Systemic Autoimmune Disease ◽  
Toll Like Receptor ◽  
Autoantibody Production ◽  
Nuclear Antigens ◽  
Deficient Mice

Systemic autoimmune disease in humans and mice is characterized by loss of immunologic tolerance to a restricted set of self-nuclear antigens. Autoantigens, such as double-stranded (ds) DNA and the RNA-containing Smith antigen (Sm), may be selectively targeted in systemic lupus erythematosus because of their ability to activate a putative common receptor. Toll-like receptor 9 (TLR9), a receptor for CpG DNA, has been implicated in the activation of autoreactive B cells in vitro, but its role in promoting autoantibody production and disease in vivo has not been determined. We show that in TLR9-deficient lupus-prone mice, the generation of anti-dsDNA and antichromatin autoantibodies is specifically inhibited. Other autoantibodies, such as anti-Sm, are maintained and even increased in TLR9-deficient mice. In contrast, ablation of TLR3, a receptor for dsRNA, did not inhibit the formation of autoantibodies to either RNA- or DNA-containing antigens. Surprisingly, we found that despite the lack of anti-dsDNA autoantibodies in TLR9-deficient mice, there was no effect on the development of clinical autoimmune disease or nephritis. These results demonstrate a specific requirement for TLR9 in autoantibody formation in vivo and indicate a critical role for innate immune activation in autoimmunity.

TNF-α promoter, Nod2 and toll-like receptor-4 polymorphisms and the in vivo and ex vivo response to endotoxin

Cytokine ◽  
2004 ◽  
Vol 26 (1) ◽  
pp. 16-24 ◽  
Author(s):  
Emile F. Schippers ◽  
Cornelis van 't Veer ◽  
Sjaak van Voorden ◽  
Cerithsa A.E. Martina ◽  
Saskia le Cessie ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Tnf Α

194 A Non-Gluten Component of Wheat is a Strong Stimulator of Innate Immune Responses In Vitro and In Vivo and Acts via Toll Like Receptor 4

2010 ◽  
Vol 138 (5) ◽  
pp. S-36
Author(s):  
Yvonne Junker ◽  
Donatella Barisani ◽  
Daniel A. Leffler ◽  
Towia Libermann ◽  
Simon T. Dillon ◽  
...  
Keyword(s):  
Immune Responses ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4

scholarly journals Involvement of Fractalkine/CX3CL1 Expression by Dendritic Cells in the Enhancement of Host Immunity against Legionella pneumophila

2005 ◽  
Vol 73 (9) ◽  
pp. 5350-5357 ◽  
Author(s):  
Toshiaki Kikuchi ◽  
Sita Andarini ◽  
Hong Xin ◽  
Kazunori Gomi ◽  
Yutaka Tokue ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Host Defense ◽  
Legionella Pneumophila ◽  
Recombinant Adenovirus ◽  
Severe Pneumonia ◽  
Adenovirus Vector ◽  
Recombinant Adenovirus Vector ◽  
Legionnaires Disease

ABSTRACT Legionnaires' disease is clinically manifested as severe pneumonia caused by Legionella pneumophila. However, the dendritic cell (DC)-centered immunological framework of the host defense against L. pneumophila has not been fully delineated. For this study, we focused on a potent chemoattractant for lymphocytes, fractalkine/CX3CL1, and observed that the fractalkine expression of DCs was somewhat up-regulated when they encountered L. pneumophila. We therefore hypothesized that fractalkine expressed by Legionella-capturing DCs is involved in the induction of T-cell-mediated immune responses against Legionella, which would be enhanced by a genetic modulation of DCs to overexpress fractalkine. In vivo immunization-challenge experiments demonstrated that DCs modified with a recombinant adenovirus vector to overexpress fractalkine (AdFKN) and pulsed with heat-killed Legionella protected immunized mice from a lethal Legionella infection and that the generation of in vivo protective immunity depended on the host lymphocyte subsets, including CD4+ T cells, CD8+ T cells, and B cells. Consistent with this, immunization with AdFKN/Legionella/DC induced significantly higher levels of serum anti-Legionella antibodies of several isotypes than those induced by control immunizations. Further analysis of spleen cells from the immunized mice indicated that the AdFKN/Legionella/DC immunization elicited Th1-dominated immune responses to L. pneumophila. These observations suggest that fractalkine may play an important role in the DC-mediated host defense against intracellular pathogens such as L. pneumophila.

Anticoagulant and antithrombotic properties of platelet protease nexin-1

Blood ◽  
2010 ◽  
Vol 115 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Yacine Boulaftali ◽  
Frédéric Adam ◽  
Laurence Venisse ◽  
Véronique Ollivier ◽  
Benjamin Richard ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Thrombus Formation ◽  
Human Platelets ◽  
Platelet Surface ◽  
Type Plasminogen Activator ◽  
Healthy Donors ◽  
Protease Nexin ◽  
Deficient Mice

AbstractProtease nexin–1 (PN-1) is a serpin that inhibits plasminogen activators, plasmin, and thrombin. PN-1 is barely detectable in plasma but is expressed by platelets. Here, we studied platelet PN-1 in resting and activated conditions and its function in thrombosis. Studies on human platelets from healthy donors and from patients with a Gray platelet syndrome demonstrate that PN-1 is present both at the platelet surface and in α-granules. The role of PN-1 was investigated in vitro using human platelets incubated with a blocking antibody and using platelets from PN-1–deficient mice. Both approaches indicate that platelet PN-1 is active on thrombin and urokinase-type plasminogen activator. Blockade and deficiency of platelet PN-1 result in accelerated and increased tissue factor-induced thrombin generation as indicated by calibrated automated thrombography. Moreover, platelets from PN-1–deficient mice respond to subthreshold doses of thrombin, as assessed by P-selectin expression and platelet aggregation. Thrombus formation, induced ex vivo by collagen in blood flow conditions and in vivo by FeCl3-induced injury, is significantly increased in PN-1–deficient mice, demonstrating the antithrombotic properties of platelet PN-1. Platelet PN-1 is thus a key player in the thrombotic process, whose negative regulatory role has been, up to now, markedly underestimated.

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