Ehrlichia chaffeensis Induces Monocyte Inflammatory Responses through MyD88, ERK, and NF-κB but Not through TRIF, Interleukin-1 Receptor 1 (IL-1R1)/IL-18R1, or Toll-Like Receptors

Miura, Kazumasa; Matsuo, Junji; Rahman, Matiur; Kumagai, Yumi; Li, Xin; Rikihisa, Yasuko

doi:10.1128/iai.05640-11

Cited by 31 publications

(39 citation statements)

References 59 publications

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“…Interestingly, it is unclear what pathways require MyD88-signaling, and the MyD88-dependent responses likely differ between cells of the innate and adaptive immune cells. It was recently reported that Ehrlichia chaffeensis , the agent of HME, induces inflammatory responses in monocytes through MyD88, ERK, and NF-kB, but did not require TLRs, the adaptor TIR-domain-containing adapter-inducing IFNβ, IL-18R, or IL-1βR (42). These data suggest the existence of previously unrecognized pathogen associated molecular patterns and cognate receptors.…”

Section: Discussionmentioning

confidence: 99%

MyD88 Signaling in CD4 T Cells Promotes IFN-γ Production and Hematopoietic Progenitor Cell Expansion in Response to Intracellular Bacterial Infection

Zhang

Jones

McCabe

et al. 2013

The Journal of Immunology

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Hematopoietic stem and progenitor cell (HSPC) phenotype and function can change in response to infectious challenge. These changes can be mediated by cytokines, interferons (IFNs), and pathogen-associated molecules, via TLR, and are thought to promote tailored immune responses for particular pathogens. Here we investigated the signals that activate HSPCs during ehrlichiosis, a disease characterized by profound hematopoietic dysfunction in both humans and mice. In a mouse model of ehrlichiosis we observed that infection-induced proliferation of bone marrow HSPCs was dependent on IFNγ signaling, and was partially dependent on MyD88. However, MyD88 was not required in HSPCs for their expansion during infection, as similar frequencies of MyD88-deficient and wild type HSPCs proliferated in mixed bone marrow chimeric mice. MyD88-deficient mice exhibited low serum and bone marrow concentration of IFNγ compared to wild type mice. We next identified CD4 T cells as the primary cells producing IFNγ in the bone marrow, and demonstrated a non-redundant role for CD4-derived IFNγ in increased HSPCs. Using mixed bone marrow chimeric mice, we identified a requirement for MyD88 in CD4 T cells for increased T-bet expression, optimal IFNγ production, and CD4 T cell proliferation. Our data demonstrate an essential role for CD4 T cells in mediating HSPC activation in response to bacterial infection, and illustrate a novel role for MyD88 signaling in CD4 T cells in this process. These findings further support the idea that IFNγ production is essential for HSPC activation and hematopoietic responses to infection.

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Section: Discussionmentioning

confidence: 99%

MyD88 Signaling in CD4 T Cells Promotes IFN-γ Production and Hematopoietic Progenitor Cell Expansion in Response to Intracellular Bacterial Infection

Zhang

Jones

McCabe

et al. 2013

The Journal of Immunology

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“…Human peripheral blood monocytes were derived from buffy coats; HEK293, RF/6A and THP-1 cells were cultured as previously described [7], [8], [54]. BMDMs were established from wild-type and DNase X −/− mice as described [8].…”

Section: Methodsmentioning

confidence: 99%

“…[1]. E. chaffeensis can replicate well in several mammalian cell lines including canine histiocytic leukemia (DH82), human acute leukemia (THP-1), human promyelocytic leukemia (HL-60), human embryonic kidney (HEK293), and monkey endothelial (RF/6A) cells [6]–[8].…”

Section: Introductionmentioning

confidence: 99%

Ehrlichia chaffeensis Uses Its Surface Protein EtpE to Bind GPI-Anchored Protein DNase X and Trigger Entry into Mammalian Cells

et al. 2013

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Ehrlichia chaffeensis, an obligatory intracellular rickettsial pathogen, enters and replicates in monocytes/macrophages and several non-phagocytic cells. E. chaffeensis entry into mammalian cells is essential not only for causing the emerging zoonosis, human monocytic ehrlichiosis, but also for its survival. It remains unclear if E. chaffeensis has evolved a specific surface protein that functions as an ‘invasin’ to mediate its entry. We report a novel entry triggering protein of Ehrlichia, EtpE that functions as an invasin. EtpE is an outer membrane protein and an antibody against EtpE (the C-terminal fragment, EtpE-C) greatly inhibited E. chaffeensis binding, entry and infection of both phagocytes and non-phagocytes. EtpE-C-immunization of mice significantly inhibited E. chaffeensis infection. EtpE-C-coated latex beads, used to investigate whether EtpE-C can mediate cell invasion, entered both phagocytes and non-phagocytes and the entry was blocked by compounds that block E. chaffeensis entry. None of these compounds blocked uptake of non-coated beads by phagocytes. Yeast two-hybrid screening revealed that DNase X, a glycosylphosphatidyl inositol-anchored mammalian cell-surface protein binds EtpE-C. This was confirmed by far-Western blotting, affinity pull-down, co-immunoprecipitation, immunofluorescence labeling, and live-cell image analysis. EtpE-C-coated beads entered bone marrow-derived macrophages (BMDMs) from wild-type mice, whereas they neither bound nor entered BMDMs from DNase X-/- mice. Antibody against DNase X or DNase X knock-down by small interfering RNA impaired E. chaffeensis binding, entry, and infection. E. chaffeensis entry and infection rates of BMDMs from DNase X-/- mice and bacterial load in the peripheral blood in experimentally infected DNase X-/- mice, were significantly lower than those from wild-type mice. Thus this obligatory intracellular pathogen evolved a unique protein EtpE that binds DNase X to enter and infect eukaryotic cells. This study is the first to demonstrate the invasin and its mammalian receptor, and their in vivo relevance in any ehrlichial species.

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“…cDNA was synthesized with random primers in ReverTra Ace quantitative PCR reverse transcription (qPCR RT) master mix (Toyobo, Osaka, Japan). qPCR was performed with primers specific for IL-1␤ (forward, 5=-ACA GAT GAA GTG CTC CTT CCA-3=; reverse, 5=-GTC GGA GAT TCG TAG CTG GAT-3=), for IL-8 (forward, 5=-CTG CGC CAA CAC AGA AAT TA-3=; reverse, 5=-ATT GCA TCT GGC AAC CCT AC-3=), for tumor necrosis factor alpha (TNF-␣) (forward, 5=-CCC CAG GGA CCT CTC TCT AA-3=; reverse, 5=-TGA GGT ACA GGC CCT CTG AT-3=) (23), and for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (forward, 5=-AAC GGG AAG CTC ACT GGC ATG-3=; reverse, 5=-TCC ACC ACC CTG TTG CTG TAG-3=) (24). The PCR conditions consisted of 5 min of denaturation at 95°C, followed by 40 cycles, each of 30 s of denaturation at 95°C, 30 s of annealing at 60°C, and 45 s of extension at 72°C.…”

Section: Methodsmentioning

confidence: 99%

Synergistic Costimulatory Effect of Chlamydia pneumoniae with Carbon Nanoparticles on NLRP3 Inflammasome-Mediated Interleukin-1β Secretion in Macrophages

et al. 2015

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The obligate intracellular bacterium Chlamydia pneumoniae is not only a causative agent of community-acquired pneumonia but is also associated with a more serious chronic disease, asthma, which might be exacerbated by air pollution containing carbon nanoparticles. Although a detailed mechanism of exacerbation remains unknown, the proinflammatory cytokine interleukin-1␤ (IL-1␤) is a critical player in the pathogenesis of asthma. C. pneumoniae induces IL-1␤ in macrophages via NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome activation and Toll-like receptor 2/4 (TLR2/4) stimulation. Carbon nanoparticles, such as carbon nanotubes (CNTs), can also evoke the NLRP3 inflammasome to trigger IL-1␤ secretion from lipopolysaccharide-primed macrophages. This study assessed whether costimulation of C. pneumoniae with CNTs synergistically enhanced IL-1␤ secretion from macrophages, and determined the molecular mechanism involved. Enhanced IL-1␤ secretion from C. pneumoniae-infected macrophages by CNTs was dose and time dependent. Transmission electron microscopy revealed that C. pneumoniae and CNTs were engulfed concurrently by macrophages. Inhibitors of actin polymerization or caspase-1, a component of the inflammasome, significantly blocked IL-1␤ secretion. Gene silencing using small interfering RNA (siRNA) targeting the NLRP3 gene also abolished IL-1␤ secretion. Other inhibitors (K ؉ efflux inhibitor, cathepsin B inhibitor, and reactive oxygen species-generating inhibitor) also blocked IL-1␤ secretion. Taken together, these findings demonstrated that CNTs synergistically enhanced IL-1␤ secretion from C. pneumoniae-infected macrophages via the NLRP3 inflammasome and caspase-1 activation, providing novel insight into our understanding of how C. pneumoniae infection can exacerbate asthma. Chlamydia pneumoniae is an obligate intracellular bacterium and a causative agent of respiratory tract infections, including community-acquired pneumonia (1, 2). The seroprevalence rates of C. pneumoniae infection, which start to rise relatively early in childhood, are increased by 50% at 20 years of age and subsequently reach 70 to 80% by 60 to 70 years of age (3, 4), suggesting most individuals will have had some exposure to the bacterium in their lifetime. Therefore, C. pneumoniae is likely a ubiquitous pathogen in individuals worldwide (4). The symptoms of pulmonary infection vary considerably according to age from asymptomatic or mild illness to serious pneumonia, especially in pediatric infection (1-3). Regarding this, several studies indicate that bacterial infection might exacerbate pulmonary inflammation and thus is associated with a more serious chronic disease, asthma (3). The proinflammatory cytokine interleukin-1␤ (IL-1␤), which is induced by C. pneumoniae (5-8), is thought to play a critical role in the development of chronic inflammatory disease, although detailed mechanisms remain unclear. Air pollution containing carbon nanoparticles, environmental air contaminants that might be easily inhaled with C. pneu...

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Ehrlichia chaffeensis Induces Monocyte Inflammatory Responses through MyD88, ERK, and NF-κB but Not through TRIF, Interleukin-1 Receptor 1 (IL-1R1)/IL-18R1, or Toll-Like Receptors

Cited by 31 publications

References 59 publications

MyD88 Signaling in CD4 T Cells Promotes IFN-γ Production and Hematopoietic Progenitor Cell Expansion in Response to Intracellular Bacterial Infection

MyD88 Signaling in CD4 T Cells Promotes IFN-γ Production and Hematopoietic Progenitor Cell Expansion in Response to Intracellular Bacterial Infection

Ehrlichia chaffeensis Uses Its Surface Protein EtpE to Bind GPI-Anchored Protein DNase X and Trigger Entry into Mammalian Cells

Synergistic Costimulatory Effect of Chlamydia pneumoniae with Carbon Nanoparticles on NLRP3 Inflammasome-Mediated Interleukin-1β Secretion in Macrophages

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