Role of Bacillus anthracis Spore Structures in Macrophage Cytokine Responses

ABSTRACT The innate immune response of macrophages (Mφ) to spores, the environmentally acquired form of Bacillus anthracis, is poorly characterized. We therefore examined the early Mφ cytokine response to B. anthracis spores, before germination. Mφ were exposed to bacilli and spores of Sterne strain 34F2 and its congenic nongerminating mutant (ΔgerH), and cytokine expression was measured by real-time PCR and an enzyme-linked immunosorbent assay. The exosporium spore layer was retained (exo+) or removed by sonication (exo−). Spores consistently induced a strong cytokine response, with the exo− spores eliciting a two- to threefold-higher response than exo+ spores. The threshold for interleukin-1β (IL-1β) production by wild-type Mφ was significantly lower than that required for tumor necrosis factor alpha expression. Cytokine production was largely dependent on MyD88, suggesting Toll-like receptor involvement; however, the expression of beta interferon in MyD88−/− Mφ suggests involvement of a MyD88-independent pathway. We conclude that (i) the B. anthracis spore is not immunologically inert, (ii) the exosporium masks epitopes recognized by the Mφ, (iii) the Mφ cytokine response to B. anthracis involves multiple pattern recognition receptors and signaling pathways, and (iv) compared to other cytokines, IL-1β is expressed at a lower spore concentration.

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Human Immunodeficiency Virus Infection Alters Tumor Necrosis Factor Alpha Production via Toll-Like Receptor-Dependent Pathways in Alveolar Macrophages and U1 Cells

Journal of Virology ◽

10.1128/jvi.00362-08 ◽

2008 ◽

Vol 82 (16) ◽

pp. 7790-7798 ◽

Cited By ~ 26

Author(s):

Marlynne Q. Nicol ◽

Jean-Marie Mathys ◽

Albertina Pereira ◽

Kevin Ollington ◽

Michael H. Ieong ◽

...

Keyword(s):

Tumor Necrosis Factor ◽

Tumor Necrosis ◽

Innate Immune ◽

Hiv Positive ◽

Toll Like Receptor ◽

Necrosis Factor Alpha ◽

Tnf Α ◽

Immunodeficiency Virus ◽

Factor Alpha ◽

Necrosis Factor

ABSTRACT Human immunodeficiency virus (HIV)-positive persons are predisposed to pulmonary infections, even after receiving effective highly active antiretroviral therapy. The reasons for this are unclear but may involve changes in innate immune function. HIV type 1 infection of macrophages impairs effector functions, including cytokine production. We observed decreased constitutive tumor necrosis factor alpha (TNF-α) concentrations and increased soluble tumor necrosis factor receptor type II (sTNFRII) in bronchoalveolar lavage fluid samples from HIV-positive subjects compared to healthy controls. Moreover, net proinflammatory TNF-α activity, as measured by the TNF-α/sTNFRII ratio, decreased as HIV-related disease progressed, as manifested by decreasing CD4 cell count and increasing HIV RNA (viral load). Since TNF-α is an important component of the innate immune system and is produced upon activation of Toll-like receptor (TLR) pathways, we hypothesized that the mechanism associated with deficient TNF-α production in the lung involved altered TLR expression or a deficit in the TLR signaling cascade. We found decreased Toll-like receptor 1 (TLR1) and TLR4 surface expression in HIV-infected U1 monocytic cells compared to the uninfected parental U937 cell line and decreased TLR message in alveolar macrophages (AMs) from HIV-positive subjects. In addition, stimulation with TLR1/2 ligand (Pam3Cys) or TLR4 ligand (lipopolysaccharide) resulted in decreased intracellular phosphorylated extracellular signal-regulated kinase and subsequent decreased transcription and expression of TNF-α in U1 cells compared to U937 cells. AMs from HIV-positive subjects also showed decreased TNF-α production in response to these TLR2 and TLR4 ligands. We postulate that HIV infection alters expression of TLRs with subsequent changes in mitogen-activated protein kinase signaling and cytokine production that ultimately leads to deficiencies of innate immune responses that predispose HIV-positive subjects to infection.

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Toll-Like Receptor 9 Is Required for Full Host Resistance toMycobacteriumaviumInfection but Plays No Role in Induction of Th1 Responses

Infection and Immunity ◽

10.1128/iai.01030-10 ◽

2011 ◽

Vol 79 (4) ◽

pp. 1638-1646 ◽

Cited By ~ 25

Author(s):

Natália B. Carvalho ◽

Fernanda S. Oliveira ◽

Fernanda V. Durães ◽

Leonardo A. de Almeida ◽

Manuela Flórido ◽

...

Keyword(s):

Interleukin 12 ◽

Toll Like Receptor ◽

Necrosis Factor Alpha ◽

Histocompatibility Complex ◽

Tnf Α ◽

Factor Alpha ◽

Ifn Γ ◽

Myd88 Signaling ◽

Necrosis Factor

ABSTRACTTo investigate the role of Toll-like receptor 9 (TLR9) in innate immunity toMycobacteriumavium, TLR9, TLR2, and MyD88 knockout (KO) mice were infected with this bacterium. Bacterial burdens were higher in the spleens, livers, and lungs of infected TLR9 KO mice than in those of C57BL/6 mice, indicating that TLR9 is required for efficient control ofM.aviuminfection. However, TLR9 KO or TLR2 KO spleen cells displayed normalM.avium-induced tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) responses. This finding was confirmed by determining the number of splenic CD4+T cells producing IFN-γ by flow cytometry. Furthermore, TLR2 and MyD88, but not TLR9, played a major role in interleukin-12 and TNF-α production byM.avium-infected macrophages and dendritic cells (DCs). We also found that major histocompatibility complex class II molecule expression on DCs is regulated by TLR2 and MyD88 signaling but not by TLR9. Finally, lack of TLR9, TLR2, or MyD88 reduced the numbers of macrophages, epithelioid cells, and lymphocytes inM.avium-induced granulomas but only MyD88 deficiency affected the number of liver granulomas. In summary, our data demonstrated that the involvement of TLR9 in the control ofM.aviuminfection is not related to the induction of Th1 responses.

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Depletion of Complement Enhances the Clearance of Brucella abortus in Mice

Infection and Immunity ◽

10.1128/iai.00567-18 ◽

2018 ◽

Vol 86 (10) ◽

Author(s):

Gabriela González-Espinoza ◽

Elías Barquero-Calvo ◽

Esteban Lizano-González ◽

Alejandro Alfaro-Alarcón ◽

Berny Arias-Gómez ◽

...

Keyword(s):

Immune System ◽

Brucella Abortus ◽

Innate Immune ◽

Control Group ◽

Bacterial Disease ◽

Necrosis Factor Alpha ◽

Content Type ◽

Factor Alpha ◽

Necrosis Factor

ABSTRACT Brucellosis is a bacterial disease of animals and humans. Brucella abortus barely activates the innate immune system at the onset of infection, and this bacterium is resistant to the microbicidal action of complement. Since complement stands as the first line of defense during bacterial invasions, we explored the role of complement in B. abortus infections. Brucella abortus-infected mice depleted of complement with cobra venom factor (CVF) showed the same survival rate as mice in the control group. The complement-depleted mice readily eliminated B. abortus from the spleen and did so more efficiently than the infected controls after 7 days of infection. The levels of the proinflammatory cytokines tumor necrosis factor alpha and interleukin-6 (IL-6) remained within background levels in complement-depleted B. abortus-infected mice. In contrast, the levels of the immune activator cytokine gamma interferon and the regulatory cytokine IL-10 were significantly increased. No significant histopathological changes in the liver and spleen were observed between the complement-depleted B. abortus-infected mice and the corresponding controls. The action exerted by Brucella on the immune system in the absence of complement may correspond to a broader phenomenon that involves several components of innate immunity.

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Role of Toll-Like Receptor 4 in the Proinflammatory Response to Vibrio cholerae O1 El Tor Strains Deficient in Production of Cholera Toxin and Accessory Toxins

Infection and Immunity ◽

10.1128/iai.73.9.6157-6164.2005 ◽

2005 ◽

Vol 73 (9) ◽

pp. 6157-6164 ◽

Cited By ~ 19

Author(s):

G. Kenneth Haines ◽

Blayne Amir Sayed ◽

Melissa S. Rohrer ◽

Verena Olivier ◽

Karla J. Fullner Satchell

Keyword(s):

Vibrio Cholerae ◽

Toll Like Receptor ◽

Proinflammatory Response ◽

Toll Like Receptor 4 ◽

Necrosis Factor Alpha ◽

Vibrio Cholerae O1 ◽

Factor Alpha ◽

El Tor ◽

Necrosis Factor

ABSTRACT Following intranasal inoculation, Vibrio cholerae KFV101 (ΔctxAB ΔhapA ΔhlyA ΔrtxA) colonizes and stimulates tumor necrosis factor alpha and interleukin 1β (IL-1β) in mice, similar to what occurs with isogenic strain P4 (ΔctxAB), but is less virulent and stimulates reduced levels of IL-6, demonstrating a role for accessory toxins in pathogenesis. Morbidity is enhanced in C3H/HeJ mice, indicating that Toll-like receptor 4 is important for infection containment.

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