scholarly journals Anthrax Lethal Toxin Impairs Innate Immune Functions of Alveolar Macrophages and Facilitates Bacillus anthracis Survival

2006 ◽  
Vol 74 (9) ◽  
pp. 5029-5034 ◽  
Author(s):  
Wilson J. Ribot ◽  
Rekha G. Panchal ◽  
Katherine C. Brittingham ◽  
Gordon Ruthel ◽  
Tara A. Kenny ◽  
...  
Keyword(s):  
Immune Responses ◽  
Bacillus Anthracis ◽  
Nonhuman Primate ◽  
Alveolar Macrophages ◽  
Lethal Toxin ◽  
Innate Immune ◽  
Binary Complex ◽  
Immune Functions ◽  
Anthrax Lethal Toxin ◽  
Ames Strain

ABSTRACT Alveolar macrophages (AM) are very important for pulmonary innate immune responses against invading inhaled pathogens because they directly kill the organisms and initiate a cascade of innate and adaptive immune responses. Although several factors contribute to inhalational anthrax, we hypothesized that unimpeded infection of Bacillus anthracis is directly linked to disabling the innate immune functions contributed by AM. Here, we investigated the effects of lethal toxin (LT), one of the binary complex virulence factors produced by B. anthracis, on freshly isolated nonhuman primate AM. Exposure of AM to doses of LT that killed susceptible macrophages had no effect on the viability of AM, despite complete MEK1 cleavage. Intoxicated AM remained fully capable of B. anthracis spore phagocytosis. However, pretreatment of AM with LT resulted in a significant decrease in the clearance of both the Sterne strain and the fully virulent Ames strain of B. anthracis, which may have been a result of impaired AM secretion of proinflammatory cytokines. Our data imply that cytolysis does not correlate with MEK1 cleavage, and this is the first report of LT-mediated impairment of nonhuman primate AM bactericidal activity against B. anthracis.

scholarly journals Bacillus anthracis Spores Stimulate Cytokine and Chemokine Innate Immune Responses in Human Alveolar Macrophages through Multiple Mitogen-Activated Protein Kinase Pathways

2006 ◽  
Vol 74 (8) ◽  
pp. 4430-4438 ◽  
Author(s):  
Kaushik Chakrabarty ◽  
Wenxin Wu ◽  
J. Leland Booth ◽  
Elizabeth S. Duggan ◽  
K. Mark Coggeshall ◽  
...  
Keyword(s):  
Immune System ◽  
Bacillus Anthracis ◽  
Alveolar Macrophages ◽  
Innate Immune System ◽  
Innate Immune ◽  
Mitogen Activated Protein Kinase ◽  
Tnf Α ◽  
Human Alveolar Macrophages ◽  
Mitogen Activated Protein ◽  
Multiple Signaling

ABSTRACT Contact with the human alveolar macrophage plays a key role in the innate immune response to Bacillus anthracis spores. Because there is a significant delay between the initial contact of the spore with the host and clinical evidence of disease, there appears to be temporary containment of the pathogen by the innate immune system. Therefore, the early macrophage response to Bacillus anthracis exposure is important in understanding the pathogenesis of this disease. In this paper, we studied the initial events after exposure to spores, beginning with the rapid internalization of spores by the macrophages. Spore exposure rapidly activated the mitogen-activated protein kinase signaling pathways extracellular signal-regulated kinase, c-Jun-NH2-terminal kinase, and p38. This was followed by the transcriptional activation of cytokine and primarily monocyte chemokine genes as determined by RNase protection assays. Transcriptional induction is reflected at the translational level, as interleukin-1α (IL-1α), IL-1β, IL-6, and tumor necrosis factor alpha (TNF-α) cytokine protein levels were markedly elevated as determined by enzyme-linked immunosorbent assay. Induction of IL-6 and TNF-α, and, to a lesser extent, IL-1α and IL-1β, was partially inhibited by the blockade of individual mitogen-activated protein kinases, while the complete inhibition of cytokine induction was achieved when multiple signaling pathway inhibitors were used. Taken together, these data clearly show activation of the innate immune system in human alveolar macrophages by Bacillus anthracis spores. The data also show that multiple signaling pathways are involved in this cytokine response. This report is the first comprehensive examination of this process in primary human alveolar macrophages.

scholarly journals Long Non-coding RNAs RN7SK and GAS5 Regulate Macrophage Polarization and Innate Immune Responses

2020 ◽  
Vol 11 ◽  
Author(s):  
Imran Ahmad ◽  
Araceli Valverde ◽  
Raza Ali Naqvi ◽  
Afsar R. Naqvi
Keyword(s):  
Immune Responses ◽  
Epigenetic Regulation ◽  
Innate Immune ◽  
Differentially Expressed ◽  
Immune Functions ◽  
Innate Immune Responses ◽  
Antigen Uptake ◽  
Non Coding Rnas

Macrophages (Mφ) are immune cells that exhibit remarkable functional plasticity. Identification of novel endogenous factors that can regulate plasticity and innate immune functions of Mφ will unravel new strategies to curb immune-related diseases. Long non-coding RNAs (lncRNAs) are a class of endogenous, non-protein coding, regulatory RNAs that are increasingly being associated with various cellular functions and diseases. Despite their ubiquity and abundance, lncRNA-mediated epigenetic regulation of Mφ polarization and innate immune functions is poorly studied. This study elucidates the regulatory role of lncRNAs in monocyte to Mφ differentiation, M1/M2 dichotomy and innate immune responses. Expression profiling of eighty-eight lncRNAs in monocytes and in vitro differentiated M2 Mφ identified seventeen differentially expressed lncRNAs. Based on fold-change and significance, we selected four differentially expressed lncRNAs viz., RN7SK, GAS5, IPW, and ZFAS1 to evaluate their functional impact. LncRNA knockdown was performed on day 3 M2 Mφ and the impact on polarization was assessed on day 7 by surface marker analysis. Knockdown of RN7SK and GAS5 showed downregulation of M2 surface markers (CD163, CD206, or Dectin) and concomitant increase in M1 markers (MHC II or CD23). RN7SK or GAS5 knockdown showed no significant impact on CD163, CD206, or CD23 transcripts. M1/M2 markers were not impacted by IPW or ZFAS1 knockdown. Functional regulation of antigen uptake/processing and phagocytosis, two central innate immune pathways, by candidate lncRNA was assessed in M1/M2 Mφ. Compared to scramble, enhanced antigen uptake and processing were observed in both M1/M2 Mφ transfected with siRNA targeting GAS5 and RN7SK but not IPW and ZFAS1. In addition, knockdown of RN7SK significantly augmented uptake of labelled E. coli in vitro by M1/M2 Mφ, while no significant difference was in GAS5 silencing cells. Together, our results highlight the instrumental role of lncRNA (RN7SK and GAS5)-mediated epigenetic regulation of macrophage differentiation, polarization, and innate immune functions.

scholarly journals The Absence of Hck, Fgr, and Lyn Tyrosine Kinases Augments Lung Innate Immune Responses to Pneumocystis murina

2009 ◽  
Vol 77 (5) ◽  
pp. 1790-1797 ◽  
Author(s):  
Michael P. Nelson ◽  
Allison E. Metz ◽  
Shaoguang Li ◽  
Clifford A. Lowell ◽  
Chad Steele
Keyword(s):  
Immune Responses ◽  
Alveolar Macrophages ◽  
Tyrosine Kinases ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Independent Manner ◽  
Intratracheal Administration ◽  
Monocyte Chemoattractant Protein 1 ◽  
Immunoglobulin Receptor

ABSTRACT Src family tyrosine kinases (SFKs) phosphorylate immunotyrosine activation motifs in the cytoplasmic tail of multiple immunoreceptors, leading to the initiation of cellular effector functions, such as phagocytosis, reactive oxygen species production, and cytokine production. SFKs also play important roles in regulating these responses through the activation of immunotyrosine inhibitory motif-containing inhibitory receptors. As myeloid cells preferentially express the SFKs Hck, Fgr, and Lyn, we questioned the role of these kinases in innate immune responses to Pneumocystis murina. Increased phosphorylation of Hck was readily detectable in alveolar macrophages after stimulation with P. murina. We further observed decreased phosphorylation of Lyn on its C-terminal inhibitory tyrosine in P. murina-stimulated alveolar macrophages, indicating that SFKs were activated in alveolar macrophages in response to P. murina. Mice deficient in Hck, Fgr, and Lyn exhibited augmented clearance 3 and 7 days after intratracheal administration of P. murina, which correlated with elevated levels of interleukin 1β (IL-1β), IL-6, CXCL1/KC, CCL2/monocyte chemoattractant protein 1, and granulocyte colony-stimulating factor in lung homogenates and a dramatic increase in macrophage and neutrophil recruitment. Augmented P. murina clearance was also observed in Lyn−/− mice 3 days postchallenge, although the level was less than that observed in Hck−/− Fgr−/− Lyn−/− mice. A correlate to augmented clearance of P. murina in Hck−/− Fgr−/− Lyn−/− mice was a greater ability of alveolar macrophages from these mice to kill P. murina in vitro, suggesting that SFKs regulate the alveolar macrophage effector function against P. murina. Mice deficient in paired immunoglobulin receptor B (PIR-B), an inhibitory receptor activated by SFKs, did not exhibit enhanced inflammatory responsiveness to or clearance of P. murina. Our results suggest that SFKs regulate innate lung responses to P. murina in a PIR-B-independent manner.

scholarly journals Analysis of Immune Responses in Acinetobacter baumannii-Infected Klotho Knockout Mice: A Mouse Model of Acinetobacter baumannii Infection in Aged Hosts

2020 ◽  
Vol 11 ◽  
Author(s):  
Yoshinori Sato ◽  
Shigeru Tansho-Nagakawa ◽  
Tsuneyuki Ubagai ◽  
Yasuo Ono
Keyword(s):  
Mouse Model ◽  
Immune Responses ◽  
Acinetobacter Baumannii ◽  
Alveolar Macrophages ◽  
Post Infection ◽  
Pulmonary Inflammation ◽  
Cell Subset ◽  
Dendritic Cell Subset ◽  
Immune Functions ◽  
Cd11b Expression

Acinetobacter baumannii is an important opportunistic pathogen that primarily afflicts elderly people. To clarify the pathogenicity of A. baumannii in the elderly, we investigated immune responses to A. baumannii ATCC 19606 infection in klotho knockout (KO) mice, the mouse model of aging. Following intravenous inoculation, the mice seldom displayed severe symptoms. However, the survival rate was 56% at 7 days post-infection. Bacteria were detected in the lungs of klotho KO mice but not klotho wildtype (WT) mice at 7 days post-infection. Neutrophils, eosinophils, interstitial macrophages, and monocyte/dendritic cell subset in the lungs of klotho KO mice were transiently induced after infection with A. baumannii. The number of alveolar macrophages in klotho KO mice was lower than that in klotho WT mice, except for 1 day post-infection. CD11b expression on neutrophils and alveolar macrophages in the lungs of klotho KO mice was seldom upregulated by the infection. These results suggested that immune functions eliminating bacteria in the lungs of klotho KO mice were insufficient. CD11blow conventional DC cells hardly increased in klotho KO mice infected with A. baumannii. Additionally, the production of interleukin (IL)-10 in the sera of klotho KO mice was significantly higher than that in klotho WT mice, whereas that production of interferon-gamma was not detected in the sera of klotho KO mice. These results suggested that acquired immune responses were hardly induced in klotho KO mice. IL-1β, CXCL1, CXCL2, and CCL2 expression was significantly higher in the lungs of klotho KO mice infected with A. baumannii than in those of klotho WT mice at 1 day post-infection. These results suggested that pulmonary inflammation was elicited in klotho KO mice during early infection. The expression levels of proinflammatory cytokines significantly correlated with TLR9 expression in the lungs of klotho KO mice. The collective results demonstrate an A. baumannii infection state in aged hosts and suggest that pulmonary inflammation and bacterial burden should be noted in aged hosts even in the absence of severe symptoms of A. baumannii infection.

scholarly journals Immunization with Attenuated Equine Herpesvirus 1 Strain KyA Induces Innate Immune Responses That Protect Mice from Lethal Challenge

2016 ◽  
Vol 90 (18) ◽  
pp. 8090-8104 ◽  
Author(s):  
Seong K. Kim ◽  
Akhalesh K. Shakya ◽  
Dennis J. O'Callaghan
Keyword(s):  
Immune Responses ◽  
Alveolar Macrophages ◽  
Innate Immune ◽  
Equine Herpesvirus ◽  
Innate Immune Responses ◽  
Lethal Challenge ◽  
Equine Herpesvirus 1 ◽  
Interferon Stimulated Genes ◽  
Ifn Γ ◽  
Herpesvirus 1

ABSTRACTEquine herpesvirus 1 (EHV-1) is a major pathogen affecting equines worldwide. The virus causes respiratory disease, abortion, and, in some cases, neurological disease. EHV-1 strain KyA is attenuated in the mouse and equine, whereas wild-type strain RacL11 induces severe inflammation of the lung, causing infected mice to succumb at 4 to 6 days postinfection. Our previous results showed that KyA immunization protected CBA mice from pathogenic RacL11 challenge at 2 and 4 weeks postimmunization and that KyA infection elicited protective humoral and cell-mediated immune responses. To investigate the protective mechanisms of innate immune responses to KyA, KyA-immunized mice were challenged with RacL11 at various times postvaccination. KyA immunization protected mice from RacL11 challenge at 1 to 7 days postimmunization. Immunized mice lost less than 10% of their body weight and rapidly regained weight. Virus titers in the lungs of KyA-immunized mice were 1,000-fold lower at 2 days post-RacL11 challenge than virus titers in the lungs of nonimmunized mice, indicating accelerated virus clearance. Affymetrix microarray analysis revealed that gamma interferon (IFN-γ) and 16 antiviral interferon-stimulated genes (ISGs) were upregulated 3.1- to 48.2-fold at 8 h postchallenge in the lungs of RacL11-challenged mice that had been immunized with KyA. Murine IFN-γ inhibited EHV-1 infection of murine alveolar macrophages and protected mice against lethal EHV-1 challenge, suggesting that IFN-γ expression is important in mediating the protection elicited by KyA immunization. These results suggest that EHV-1 KyA may be used as a live attenuated EHV-1 vaccine as well as a prophylactic agent in horses.IMPORTANCEViral infection of cells initiates a signal cascade of events that ultimately attempts to limit viral replication and prevent infection through the expression of host antiviral proteins. In this study, we show that EHV-1 KyA immunization effectively protected CBA mice from pathogenic RacL11 challenge at 1 to 7 days postvaccination and increased the expression of IFN-γ and 16 antiviral interferon-stimulated genes (ISGs). The administration of IFN-γ blocked EHV-1 replication in murine alveolar macrophages and mouse lungs and protected mice from lethal challenge. To our knowledge, this is the first report of an attenuated EHV-1 vaccine that protects the animal at 1 to 7 days postimmunization by innate immune responses. Our findings suggested that IFN-γ serves as a novel prophylactic agent and may offer new strategies for the development of anti-EHV-1 agents in the equine.

Innate Immune Responses to Replication of Porcine Reproductive And Respiratory Syndrome Virus in Isolated Swine Alveolar Macrophages

2007 ◽  
Vol 20 (1) ◽  
pp. 105-118 ◽  
Author(s):  
Tahar Ait-Ali ◽  
Alison D. Wilson ◽  
David G. Westcott ◽  
Mary Clapperton ◽  
Martin Waterfall ◽  
...  
Keyword(s):  
Immune Responses ◽  
Alveolar Macrophages ◽  
Innate Immune ◽  
Respiratory Syndrome Virus ◽  
Innate Immune Responses

scholarly journals Role of K+ Channels in Alveolar Macrophages-Mediated Inflammatory Response upon Anthrax Lethal Toxin Stimulation

2013 ◽  
Vol 104 (2) ◽  
pp. 132a
Author(s):  
Johnson Thomas ◽  
Jordon Metcalf ◽  
John W. Christman ◽  
James Cook ◽  
Irena Levitan
Keyword(s):  
Inflammatory Response ◽  
Alveolar Macrophages ◽  
Lethal Toxin ◽  
Anthrax Lethal Toxin ◽  
K Channels

scholarly journals Correlation between Lethal Toxin-Neutralizing Antibody Titers and Protection from Intranasal Challenge with Bacillus anthracis Ames Strain Spores in Mice after Transcutaneous Immunization with Recombinant Anthrax Protective Antigen

2006 ◽  
Vol 74 (1) ◽  
pp. 794-797 ◽  
Author(s):  
Kristina K. Peachman ◽  
Mangala Rao ◽  
Carl R. Alving ◽  
Robert Burge ◽  
Stephen H. Leppla ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Protective Antigen ◽  
Neutralizing Antibody ◽  
Lethal Toxin ◽  
Vaccine Strategy ◽  
Transcutaneous Immunization ◽  
Antibody Titers ◽  
Anthrax Protective Antigen ◽  
Ames Strain ◽  
Recombinant Protective Antigen

ABSTRACT Transcutaneous immunization of mice with recombinant protective antigen (rPA) of Bacillus anthracis resulted in significantly higher lethal toxin-neutralizing antibody titers than did intramuscular injection of alum-adsorbed rPA. Immunized mice were partially protected against intranasal challenge with 235,000 (10 50% lethal doses) Ames strain B. anthracis spores. A highly significant correlation was observed between toxin-neutralizing antibody titer and survival after challenge. Future experiments with rabbits and nonhuman primates should confirm the significance of protection by this vaccine strategy.

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