scholarly journals Factor XI-Deficient Mice Display Reduced Inflammation, Coagulopathy, and Bacterial Growth during Listeriosis

2011 ◽  
Vol 80 (1) ◽  
pp. 91-99 ◽  
Author(s):  
Deyan Luo ◽  
Frank M. Szaba ◽  
Lawrence W. Kummer ◽  
Lawrence L. Johnson ◽  
Erik I. Tucker ◽  
...  

ABSTRACTIn mice infected sublethally withListeria monocytogenes, fibrin is deposited at low levels within hepatic tissue, where it functions protectively by limiting bacterial growth and suppressing hemorrhagic pathology. Here we demonstrate that mice infected with lethal doses ofL. monocytogenesproduce higher levels of fibrin and display evidence of systemic coagulopathy (i.e., thrombocytopenia, fibrinogen depletion, and elevated levels of thrombin-antithrombin complexes). When the hepatic bacterial burden exceeds 1 × 106CFU, levels of hepatic fibrin correlate with the bacterial burden, which also correlates with levels of hepatic mRNA encoding the hemostatic enzyme factor XI (FXI). Gene-targeted FXI-deficient mice show significantly improved survival upon challenge with high doses ofL. monocytogenesand also display reduced levels of hepatic fibrin, decreased evidence of coagulopathy, and diminished cytokine production (interleukin-6 [IL-6] and IL-10). While fibrin limits the bacterial burden during sublethal listeriosis in wild-type mice, FXI-deficient mice display a significantly improved capacity to restrain the bacterial burden during lethal listeriosis despite their reduced fibrin levels. They also show less evidence of hepatic necrosis. In conjunction with suboptimal antibiotic therapy, FXI-specific monoclonal antibody 14E11 improves survival when administered therapeutically to wild-type mice challenged with high doses ofL. monocytogenes.Together, these findings demonstrate the utility of murine listeriosis as a model for dissecting qualitative differences between protective and pathological host responses and reveal novel roles for FXI in exacerbating inflammation and pathogen burden during a lethal bacterial infection.

2015 ◽  
Vol 83 (3) ◽  
pp. 1210-1216 ◽  
Author(s):  
Júlia Silveira Fahel ◽  
Mariana Bueno de Souza ◽  
Marco Túlio Ribeiro Gomes ◽  
Patricia P. Corsetti ◽  
Natalia B. Carvalho ◽  
...  

Brucella abortusis a Gram-negative bacterium that infects humans and cattle, causing a chronic inflammatory disease known as brucellosis. A Th1-mediated immune response plays a critical role in host control of this pathogen. Recent findings indicate contrasting roles for lipid mediators in host responses against infections. 5-Lipoxygenase (5-LO) is an enzyme required for the production of the lipid mediators leukotrienes and lipoxins. To determine the involvement of 5-LO in host responses toB. abortusinfection, we intraperitoneally infected wild-type and 5-LO-deficient mice and evaluated the progression of infection and concomitant expression of immune mediators. Here, we demonstrate thatB. abortusinduced the upregulation of 5-LO mRNA in wild-type mice. Moreover, this pathogen upregulated the production of the lipid mediators leukotriene B4and lipoxin A4in a 5-LO-dependent manner. 5-LO-deficient mice displayed lower bacterial burdens in the spleen and liver and less severe liver pathology, demonstrating an enhanced resistance to infection. Host resistance paralleled an increased expression of the proinflammatory mediators interleukin-12 (IL-12), gamma interferon (IFN-γ), and inducible nitric oxide synthase (iNOS) during the course of infection. Moreover, we demonstrated that 5-LO downregulated the expression of IL-12 in macrophages duringB. abortusinfection. Our results suggest that 5-LO has a major involvement inB. abortusinfection, by functioning as a negative regulator of the protective Th1 immune responses against this pathogen.


mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Adria Carbo ◽  
Danyvid Olivares-Villagómez ◽  
Raquel Hontecillas ◽  
Josep Bassaganya-Riera ◽  
Rupesh Chaturvedi ◽  
...  

ABSTRACTThe development of gastritis duringHelicobacter pyloriinfection is dependent on an activated adaptive immune response orchestrated by T helper (Th) cells. However, the relative contributions of the Th1 and Th17 subsets to gastritis and control of infection are still under investigation. To investigate the role of interleukin-21 (IL-21) in the gastric mucosa duringH. pyloriinfection, we combined mathematical modeling of CD4+T cell differentiation within vivomechanistic studies. We infected IL-21-deficient and wild-type mice withH. pyloristrain SS1 and assessed colonization, gastric inflammation, cellular infiltration, and cytokine profiles. ChronicallyH. pylori-infected IL-21-deficient mice had higherH. pyloricolonization, significantly less gastritis, and reduced expression of proinflammatory cytokines and chemokines compared to these parameters in infected wild-type littermates. Thesein vivodata were used to calibrate anH. pyloriinfection-dependent, CD4+T cell-specific computational model, which then described the mechanism by which IL-21 activates the production of interferon gamma (IFN-γ) and IL-17 during chronicH. pyloriinfection. The model predicted activated expression of T-bet and RORγt and the phosphorylation of STAT3 and STAT1 and suggested a potential role of IL-21 in the modulation of IL-10. Driven by our modeling-derived predictions, we found reduced levels of CD4+splenocyte-specifictbx21androrcexpression, reduced phosphorylation of STAT1 and STAT3, and an increase in CD4+T cell-specific IL-10 expression inH. pylori-infected IL-21-deficient mice. Our results indicate that IL-21 regulates Th1 and Th17 effector responses during chronicH. pyloriinfection in a STAT1- and STAT3-dependent manner, therefore playing a major role controllingH. pyloriinfection and gastritis.IMPORTANCEHelicobacter pyloriis the dominant member of the gastric microbiota in more than 50% of the world’s population.H. pyloricolonization has been implicated in gastritis and gastric cancer, as infection withH. pyloriis the single most common risk factor for gastric cancer. Current data suggest that, in addition to bacterial virulence factors, the magnitude and types of immune responses influence the outcome of colonization and chronic infection. This study uses a combined computational and experimental approach to investigate how IL-21, a proinflammatory T cell-derived cytokine, maintains the chronic proinflammatory T cell immune response driving chronic gastritis duringH. pyloriinfection. This research will also provide insight into a myriad of other infectious and immune disorders in which IL-21 is increasingly recognized to play a central role. The use of IL-21-related therapies may provide treatment options for individuals chronically colonized withH. pylorias an alternative to aggressive antibiotics.


2018 ◽  
Vol 87 (2) ◽  
Author(s):  
Patrick M. Meyer Sauteur ◽  
Adrianus C. J. M. de Bruijn ◽  
Catarina Graça ◽  
Anne P. Tio-Gillen ◽  
Silvia C. Estevão ◽  
...  

ABSTRACTAntibody responses toMycoplasma pneumoniaecorrelate with pulmonaryM. pneumoniaeclearance. However,M. pneumoniae-specific IgG antibodies can cross-react with the myelin glycolipid galactocerebroside (GalC) and cause neurological disorders. We assessed whether antiglycolipid antibody formation is part of the physiological immune response toM. pneumoniae. We show that antibodies againstM. pneumoniaeproteins and glycolipids arise in serum ofM. pneumoniae-infected children and mice. Although antibodies toM. pneumoniaeglycolipids were mainly IgG, anti-GalC antibodies were only IgM. B-1a cells, shown to aid in protection against pathogen-derived glycolipids, are lacking in Bruton tyrosine kinase (Btk)-deficient mice.M. pneumoniae-infected Btk-deficient mice developedM. pneumoniae-specific IgG responses toM. pneumoniaeproteins but not toM. pneumoniaeglycolipids, including GalC. The equal recovery fromM. pneumoniaeinfection in Btk-deficient and wild-type mice suggests that pulmonaryM. pneumoniaeclearance is predominantly mediated by IgG reactive withM. pneumoniaeproteins and thatM. pneumoniaeglycolipid-specific IgG or IgM is not essential. These data will guide the development ofM. pneumoniae-targeting vaccines that avoid the induction of neurotoxic antibodies.


mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Masayuki Nakajima ◽  
Masashi Matsuyama ◽  
Mio Kawaguchi ◽  
Takumi Kiwamoto ◽  
Yosuke Matsuno ◽  
...  

ABSTRACT Nrf2 is a redox-sensitive transcription factor that is thought to be important in protection against intracellular pathogens. To determine the protective role of Nrf2 in the host defense against Mycobacterium avium complex (MAC), both wild-type and Nrf2-deficient mice were intranasally infected with MAC bacteria. Nrf2-deficient mice were highly susceptible to MAC bacteria compared with wild-type mice. There were no significant changes in the levels of oxidative stress and Th1 cytokine production between genotypes. Comprehensive transcriptome analysis showed that the expressions of Nramp1 and HO-1 were much lower in the infected lungs, and the expression of Nramp1 was especially lower in alveolar macrophages of Nrf2-deficient mice than of wild-type mice. Electron microscopy showed that many infected alveolar macrophages from Nrf2-deficient mice contained a large number of intracellular MAC bacteria with little formation of phagolysosomes, compared with those from wild-type mice. Treatment with sulforaphane, an activator of Nrf2, increased resistance to MAC with increased lung expression of Nramp1 and HO-1 in wild-type mice. These results indicate that Nramp1 and HO-1, regulated by Nrf2, are essential in defending against MAC infection due to the promotion of phagolysosome fusion and granuloma formation, respectively. Thus, Nrf2 is thought to be a critical determinant of host resistance to MAC infection. IMPORTANCE Nontuberculous mycobacteria (NTM) are an important cause of morbidity and mortality in pulmonary infections. Among them, Mycobacterium avium complex (MAC) is the most common cause of pulmonary NTM disease worldwide. It is thought that both environmental exposure and host susceptibility are required for the establishment of pulmonary MAC disease, because pulmonary MAC diseases are most commonly observed in slender, postmenopausal women without a clearly recognized immunodeficiency. However, host factors that regulate MAC susceptibility have not been elucidated until now. This study shows that Nrf2 is a critical regulator of host susceptibility to pulmonary MAC disease by promoting phagolysosome fusion and granuloma formation via activating Nramp1 and HO-1 genes, respectively. The Nrf2 system is activated in alveolar macrophages, the most important cells during MAC infection, as both the main reservoir of infection and bacillus-killing cells. Thus, augmentation of Nrf2 might be a useful therapeutic approach for protection against pulmonary MAC disease.


2014 ◽  
Vol 82 (4) ◽  
pp. 1698-1709 ◽  
Author(s):  
Yubin Zhang ◽  
Vinh Thai ◽  
Amanda McCabe ◽  
Maura Jones ◽  
Katherine C. MacNamara

ABSTRACTHuman monocytic ehrlichiosis (HME) is caused by a tick-borne obligate intracellular pathogen of the orderRickettsiales. HME disease can range from mild to a fatal, toxic shock-like syndrome, yet the mechanisms regulating pathogenesis are not well understood. We define a central role for type I interferons (alpha interferon [IFN-α] and IFN-β) in severe disease in a mouse model of fatal ehrlichiosis caused byIxodes ovatusEhrlichia(IOE). IFN-α and IFN-β were induced by IOE infection but not in response to a less virulent strain,Ehrlichia muris. The major sources of type I IFNs during IOE infection were plasmacytoid dendritic cells and monocytes. Mice lacking the receptor for type I IFNs (Ifnardeficient) or neutralization of IFN-α and IFN-β resulted in a reduced bacterial burden.Ifnar-deficient mice exhibited significantly increased survival after IOE infection, relative to that of wild-type (WT) mice, that correlated with increased type II IFN (IFN-γ) production. Pathogen-specific antibody responses were also elevated inIfnar-deficient mice, and this required IFN-γ. Remarkably, increased IFN-γ and IgM were not essential for protection in the absence of type I IFN signaling. The direct effect of type I IFNs on hematopoietic and nonhematopoietic cells was evaluated in bone marrow chimeric mice. We observed that chimeric mice containingIfnar-deficient hematopoietic cells succumbed to infection early, whereasIfnar-deficient mice containing WT hematopoietic cells exhibited increased survival, despite having a higher bacterial burden. These data demonstrate that IFN-α receptor signaling in nonhematopoietic cells is important for pathogenesis. Thus, type I IFNs are induced during a rickettsial infectionin vivoand promote severe disease.


2006 ◽  
Vol 74 (11) ◽  
pp. 6092-6099 ◽  
Author(s):  
Alissa A. Chackerian ◽  
Shi-Juan Chen ◽  
Scott J. Brodie ◽  
Jeanine D. Mattson ◽  
Terrill K. McClanahan ◽  
...  

ABSTRACT Interleukin-23 (IL-23), a member of the IL-12 family, is a heterodimeric cytokine that is composed of the p40 subunit of IL-12 plus a unique p19 subunit. IL-23 is critical for autoimmune inflammation, in part due to its stimulation of the proinflammatory cytokine IL-17A. It is less clear, however, if IL-23 is required during the immune response to pathogens. We examined the role of IL-23 during Mycobacterium bovis BCG infection. We found that IL-23 reduces the bacterial burden and promotes granuloma formation when IL-12 is absent. However, IL-23 does not contribute substantially to host resistance when IL-12 is present, as the ability to control bacterial growth and form granulomata is not affected in IL-23p19-deficient mice and mice treated with a specific anti-IL-23p19 antibody. IL-23p19-deficient mice are also able to mount an effective memory response to secondary infection with BCG. While IL-23p19-deficient mice do not produce IL-17A, this cytokine is not necessary for effective control of infection, and antibody blocking of IL-17A in both wild-type and IL-12-deficient mice also has little effect on the bacterial burden. These data suggest that IL-23 by itself does not play an essential role in the protective immune response to BCG infection; however, the presence of IL-23 can partially compensate for the absence of IL-12. Furthermore, neutralization of IL-23 or IL-17A does not increase susceptibility to mycobacterial BCG infection.


2018 ◽  
Vol 86 (7) ◽  
pp. e00143-18 ◽  
Author(s):  
Taylor B. Poston ◽  
Catherine M. O'Connell ◽  
Jenna Girardi ◽  
Jeanne E. Sullivan ◽  
Uma M. Nagarajan ◽  
...  

ABSTRACTCD4 T cells and antibody are required for optimal acquired immunity toChlamydia muridarumgenital tract infection, and T cell-mediated gamma interferon (IFN-γ) production is necessary to clear infection in the absence of humoral immunity. However, the role of T cell-independent immune responses during primary infection remains unclear. We investigated this question by inoculating wild-type and immune-deficient mice withC. muridarumCM001, a clonal isolate capable of enhanced extragenital replication. Genital inoculation of wild-type mice resulted in transient dissemination to the lungs and spleen that then was rapidly cleared from these organs. However, CM001 genital infection proved lethal forSTAT1−/−andIFNG−/−mice, in which IFN-γ signaling was absent, and forRag1−/−mice, which lacked T and B cells and in which innate IFN-γ signaling was retained. In contrast, B cell-deficient muMT mice, which can generate a Th1 response, and T cell-deficient mice with intact B cell and innate IFN-γ signaling survived. These data collectively indicate that IFN-γ prevents lethal CM001 dissemination in the absence of T cells and suggests a B cell corequirement. Adoptive transfer of convalescent-phase immune serum but not naive IgM toRag1−/−mice infected with CM001 significantly increased the survival time, while transfer of naive B cells completely rescuedRag1−/−mice from CM001 lethality. Protection was associated with a significant reduction in the lung chlamydial burden of genitally infected mice. These data reveal an important cooperation between T cell-independent B cell responses and innate IFN-γ in chlamydial host defense and suggest that interactions between T cell-independent antibody and IFN-γ are essential for limiting extragenital dissemination.


mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Manli Na ◽  
Zhicheng Hu ◽  
Majd Mohammad ◽  
Mariana do Nascimento Stroparo ◽  
Abukar Ali ◽  
...  

ABSTRACT Septic arthritis, one of the most dangerous joint diseases, is predominantly caused by Staphylococcus aureus. In contrast, coagulase-negative staphylococci are rarely found in septic arthritis. We hypothesize that coagulases released by S. aureus, including coagulase (Coa) and von Willebrand factor-binding protein (vWbp), play potent roles in the induction of septic arthritis. Four isogenic S. aureus strains differing in expression of coagulases (wild-type [WT] Newman, Δcoa, Δvwb, and Δcoa Δvwb) were used to induce septic arthritis in both wild-type and von Willebrand factor (vWF)-deficient mice. Septic arthritis severity was greatly reduced when wild-type mice were infected with the Δcoa Δvwb and Δvwb variants compared to WT or Δcoa strains, suggesting that vWbp rather than Coa is a major virulence factor in S. aureus septic arthritis. vWF-deficient mice were more susceptible to bone damage in septic arthritis, especially when the Δvwb strain was used. Importantly, no difference in arthritis severity between the Δvwb and WT strains was observed in vWF-deficient mice. Collectively, we conclude that vWbp production by S. aureus enhances staphylococcal septic arthritis. IMPORTANCE Septic arthritis remains one of the most dangerous joint diseases with a rapidly progressive disease character. Despite advances in the use of antibiotics, permanent reductions in joint function due to joint deformation and deleterious contractures occur in up to 50% of patients with septic arthritis. So far, it is still largely unknown how S. aureus initiates and establishes joint infection. Here, we demonstrate that von Willebrand factor-binding protein expressed by S. aureus facilitates the initiation of septic arthritis. Such effect might be mediated through its interaction with a host factor (von Willebrand factor). Our finding contributes significantly to the full understanding of septic arthritis etiology and will pave the way for new therapeutic modalities for this devastating disease.


1994 ◽  
Vol 180 (4) ◽  
pp. 1243-1250 ◽  
Author(s):  
E Fattori ◽  
M Cappelletti ◽  
P Costa ◽  
C Sellitto ◽  
L Cantoni ◽  
...  

Systemic and localized inflammation elicit a number of host responses which include fever, cachexia, hypoglycemia, and major changes in the concentration of liver plasma proteins. Interleukin 6 (IL-6) is considered an important mediator of the inflammatory response, together with IL-1 and tumor necrosis factor alpha (TNF-alpha). The purpose of this study was to unequivocally determine the role of IL-6 in these phenomena making use of IL-6-deficient mice that we have recently generated by gene targeting. We report here that in the absence of IL-6, mice are unable to mount a normal inflammatory response to localized tissue damage generated by turpentine injection. The induction of acute phase proteins is dramatically reduced, mice do not lose body weight and only suffer from mild anorexia and hypoglycemia. In contrast, when systemic inflammation is elicited through the injection of bacterial lipopolysaccharide (LPS), these parameters are altered to the same extent both in wild-type and IL-6-deficient mice, demonstrating that under these conditions IL-6 function is dispensable. Moreover, we show that LPS-treated IL-6-deficient mice produce three times more TNF-alpha than wild-type controls, suggesting that increased TNF-alpha production might be one of the compensatory mechanisms through which a normal response to LPS is achieved in the absence of IL-6. We also show that corticosterone is normally induced in IL-6-deficient mice, demonstrating that IL-6 is not required for the activation of the hypothalamic-pituitary-adrenal axis. Our results reinforce the idea that different patterns of cytokines are involved in systemic and localized tissue damage, and identify IL-6 as an essential mediator of the inflammatory response to localized inflammation.


2012 ◽  
Vol 81 (3) ◽  
pp. 723-732 ◽  
Author(s):  
Simon Clare ◽  
Victoria John ◽  
Alan W. Walker ◽  
Jennifer L. Hill ◽  
Cei Abreu-Goodger ◽  
...  

ABSTRACTMicroRNAs (miRNAs) are small noncoding molecules that control gene expression posttranscriptionally, with microRNA-155 (miR-155) one of the first to be implicated in immune regulation. Here, we show that miR-155-deficient mice are less able to eradicate a mucosalCitrobacter rodentiuminfection than wild-type C57BL/6 mice. miR-155-deficient mice exhibited prolonged colonization associated with a higherC. rodentiumburden in gastrointestinal tissue and spread into systemic tissues. Germinal center formation and humoral immune responses againstC. rodentiumwere severely impaired in infected miR-155-deficient mice. A similarly susceptible phenotype was observed in μMT mice reconstituted with miR-155-deficient B cells, indicating that miR-155 is required intrinsically for mediating protection against this predominantly luminal bacterial pathogen.


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