scholarly journals Hif-1alpha induced expression of Il-1beta protects against mycobacterial infection in zebrafish

2018 ◽  
Author(s):  
Nikolay V. Ogryzko ◽  
Amy Lewis ◽  
Heather L. Wilson ◽  
Annemarie H. Meijer ◽  
Stephen A. Renshaw ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Immune Response ◽  
Mycobacterial Infection ◽  
Innate Immune ◽  
Protective Mechanism ◽  
Drug Resistant ◽  
Data Link ◽  
Disease Outcomes ◽  
Protection Against Infection

AbstractDrug resistant mycobacteria are a rising problem worldwide. There is an urgent need to understand the immune response to TB to identify host targets that, if targeted therapeutically, could be used to tackle these currently untreatable infections. Here, we use an Il-1β fluorescent transgenic line to show that there is an early innate immune pro-inflammatory response to well-established zebrafish models of inflammation and Mycobacterium marinum (Mm) infection. We demonstrate that host-derived hypoxia signalling, mediated by the Hif-1α transcription factor, can prime macrophages with increased levels of Il-1β in the absence of infection, upregulating neutrophil antimicrobial nitric oxide production, leading to greater protection against infection. Our data link Hif-1α to proinflammatory macrophage Il-1β transcription in vivo during early mycobacterial infection and importantly highlight a host protective mechanism, via antimicrobial nitric oxide, that decreases disease outcomes and that could be targeted therapeutically to stimulate the innate immune response to better deal with infections.

scholarly journals Sirtuin 7 Regulates Nitric Oxide Production and Apoptosis to Promote Mycobacterial Clearance in Macrophages

2021 ◽  
Vol 12 ◽  
Author(s):  
Su Zhang ◽  
Yaya Liu ◽  
Xuefeng Zhou ◽  
Min Ou ◽  
Guohui Xiao ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Mycobacterial Infection ◽  
Protective Mechanism ◽  
No Production ◽  
Host Immune System ◽  
Drug Resistant ◽  
Bacterial Burden ◽  
Intracellular Growth ◽  
No Donor ◽  
Infection Inhibition

The host immune system plays a pivotal role in the containment of Mycobacterium tuberculosis (Mtb) infection, and host-directed therapy (HDT) is emerging as an effective strategy to treat tuberculosis (TB), especially drug-resistant TB. Previous studies revealed that expression of sirtuin 7 (SIRT7), a nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase, was downregulated in macrophages after Mycobacterial infection. Inhibition of SIRT7 with the pan-sirtuin family inhibitor nicotinamide (NAM), or by silencing SIRT7 expression, promoted intracellular growth of Mtb and restricted the generation of nitric oxide (NO). Addition of the exogenous NO donor SNAP abrogated the increased bacterial burden in NAM-treated or SIRT7-silenced macrophages. Furthermore, SIRT7-silenced macrophages displayed a lower frequency of early apoptotic cells after Mycobacterial infection, and this could be reversed by providing exogenous NO. Overall, this study clarified a SIRT7-mediated protective mechanism against Mycobacterial infection through regulation of NO production and apoptosis. SIRT7 therefore has potential to be exploited as a novel effective target for HDT of TB.

scholarly journals Modulation of in vivo alloreactivity by inhibition of inducible nitric oxide synthase.

1995 ◽  
Vol 181 (1) ◽  
pp. 63-70 ◽  
Author(s):  
N K Worrall ◽  
W D Lazenby ◽  
T P Misko ◽  
T S Lin ◽  
C P Rodi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Immune Response ◽  
Nitric Oxide Synthase ◽  
Inducible Nitric Oxide Synthase ◽  
Biologically Active ◽  
Nitric Oxide Production ◽  
Oxide Production ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

The role of nitric oxide in the immune response to allogeneic tissue was explored in an in vivo cardiac transplant model in the rat. Nitric oxide production during organ rejection was demonstrated by elevations in systemic serum nitrite/nitrate levels and by electron paramagnetic resonance spectroscopy. Messenger RNA for the inducible nitric oxide synthase enzyme was detected in the rejecting allografted heart, but not in the nonrejecting isografted heart. The enzyme was demonstrated to be biologically active by the in vitro conversion of L-arginine to L-citrulline and was immunohistochemically localized to the infiltrating inflammatory cells. Treatment with aminoguanidine, a preferential inhibitor of the inducible nitric oxide synthase isoform, prevented the increased nitric oxide production in the transplanted organ and significantly attenuated the pathogenesis of acute rejection. Aminoguanidine treatment prolonged graft survival, improved graft contractile function, and significantly reduced the histologic grade of rejection. These results suggest an important role for nitric oxide in mediating the immune response to allogeneic tissue. Inhibition of inducible nitric oxide synthase may provide a novel therapeutic modality in the management of acute transplant rejection and of other immune-mediated processes.

scholarly journals Occurrence of foamy macrophages during the innate response of zebrafish to trypanosome infections

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Sem H Jacobs ◽  
Eva Dóró ◽  
Ffion R Hammond ◽  
Mai E Nguyen-Chi ◽  
Georges Lutfalla ◽  
...  
Keyword(s):  
Immune Response ◽  
Early Response ◽  
Innate Immune ◽  
Infection Model ◽  
Parasite Control ◽  
Innate Response ◽  
Larval Zebrafish ◽  
Inflammatory Profile ◽  
Foamy Macrophages

A tightly regulated innate immune response to trypanosome infections is critical to strike a balance between parasite control and inflammation-associated pathology. In this study, we make use of the recently established Trypanosoma carassii infection model in larval zebrafish to study the early response of macrophages and neutrophils to trypanosome infections in vivo. We consistently identified high- and low-infected individuals and were able to simultaneously characterize their differential innate response. Not only did macrophage and neutrophil number and distribution differ between the two groups, but also macrophage morphology and activation state. Exclusive to high-infected zebrafish, was the occurrence of foamy macrophages characterized by a strong pro-inflammatory profile and potentially associated with an exacerbated immune response as well as susceptibility to the infection. To our knowledge this is the first report of the occurrence of foamy macrophages during an extracellular trypanosome infection.

scholarly journals Ursodeoxycholic Acid (UDCA) Mitigates the Host Inflammatory Response during Clostridioides difficile Infection by Altering Gut Bile Acids

2020 ◽  
Vol 88 (6) ◽  
Author(s):  
Jenessa A. Winston ◽  
Alissa J. Rivera ◽  
Jingwei Cai ◽  
Rajani Thanissery ◽  
Stephanie A. Montgomery ◽  
...  
Keyword(s):  
Immune Response ◽  
Bile Acid ◽  
Inflammatory Response ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Colonization Resistance ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile infection (CDI) is associated with increasing morbidity and mortality posing an urgent threat to public health. Recurrence of CDI after successful treatment with antibiotics is high, thus necessitating discovery of novel therapeutics against this enteric pathogen. Administration of the secondary bile acid ursodeoxycholic acid (UDCA; ursodiol) inhibits the life cycles of various strains of C. difficile in vitro, suggesting that the FDA-approved formulation of UDCA, known as ursodiol, may be able to restore colonization resistance against C. difficile in vivo. However, the mechanism(s) by which ursodiol is able to restore colonization resistance against C. difficile remains unknown. Here, we confirmed that ursodiol inhibits C. difficile R20291 spore germination and outgrowth, growth, and toxin activity in a dose-dependent manner in vitro. In a murine model of CDI, exogenous administration of ursodiol resulted in significant alterations in the bile acid metabolome with little to no changes in gut microbial community structure. Ursodiol pretreatment resulted in attenuation of CDI pathogenesis early in the course of disease, which coincided with alterations in the cecal and colonic inflammatory transcriptome, bile acid-activated receptors nuclear farnesoid X receptor (FXR) and transmembrane G-protein-coupled membrane receptor 5 (TGR5), which are able to modulate the innate immune response through signaling pathways such as NF-κB. Although ursodiol pretreatment did not result in a consistent decrease in the C. difficile life cycle in vivo, it was able to attenuate an overly robust inflammatory response that is detrimental to the host during CDI. Ursodiol remains a viable nonantibiotic treatment and/or prevention strategy against CDI. Likewise, modulation of the host innate immune response via bile acid-activated receptors FXR and TGR5 represents a new potential treatment strategy for patients with CDI.

scholarly journals Effects of Regulatory T Cell Depletion on NK Cell Responses against Listeria monocytogenes in Feline Immunodeficiency Virus Infected Cats

Viruses ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 984
Author(s):  
Simões ◽  
LaVoy ◽  
Dean
Keyword(s):  
Immune Response ◽  
Listeria Monocytogenes ◽  
Dendritic Cell ◽  
Innate Immune Response ◽  
Feline Immunodeficiency Virus ◽  
Innate Immune ◽  
Treg Depletion ◽  
Cell Responses ◽  
Immunodeficiency Virus

Regulatory T cells (Treg) are key players in the maintenance of peripheral tolerance, preventing autoimmune diseases and restraining chronic inflammatory diseases. Evidence suggests Treg cells and NK cells have important roles in feline immunodeficiency virus (FIV) pathogenesis; however, in vivo studies investigating the interplay between these two cell populations are lacking. We previously described innate immune defects in FIV-infected cats characterized by cytokine deficits and impaired natural killer cell (NK) and NK T cell (NKT) functions. In this study, we investigated whether in vivo Treg depletion by treatment with an anti-feline CD25 monoclonal antibody would improve the innate immune response against subcutaneous challenge with Listeria monocytogenes (Lm). Treg depletion resulted in an increased overall number of cells in Lm-draining lymph nodes and increased proliferation of NK and NKT cells in FIV-infected cats. Treg depletion did not normalize expression of perforin or granzyme A by NK and NKT cells, nor did Treg depletion result in improved clearance of Lm. Thus, despite the quantitative improvements in the NK and NKT cell responses to Lm, there was no functional improvement in the early control of Lm. CD1a+ dendritic cell percentages in the lymph nodes of FIV-infected cats were lower than in specific-pathogen-free control cats and failed to upregulate CD80 even when Treg were depleted. Taken together, Treg depletion failed to improve the innate immune response of FIV-infected cats against Lm and this may be due to dendritic cell dysfunction.

scholarly journals The Exopolysaccharide of Lactobacillus fermentum UCO-979C Is Partially Involved in Its Immunomodulatory Effect and Its Ability to Improve the Resistance against Helicobacter pylori Infection

2020 ◽  
Vol 8 (4) ◽  
pp. 479
Author(s):  
Valeria Garcia-Castillo ◽  
Guillermo Marcial ◽  
Leonardo Albarracín ◽  
Mikado Tomokiyo ◽  
Patricia Clua ◽  
...  
Keyword(s):  
Immune Response ◽  
Helicobacter Pylori ◽  
Gastric Mucosa ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Helicobacter Pylori Infection ◽  
Beneficial Effects ◽  
Ifn Γ ◽  
H Pylori

Lactobacillus fermentum UCO-979C (Lf979C) beneficially modulates the cytokine response of gastric epithelial cells and macrophages after Helicobacter pylori infection in vitro. Nevertheless, no in vivo studies were performed with this strain to confirm its beneficial immunomodulatory effects. This work evaluated whether Lf979C improves protection against H. pylori infection in mice by modulating the innate immune response. In addition, we evaluated whether its exopolysaccharide (EPS) was involved in its beneficial effects. Lf979C significantly reduced TNF-α, IL-8, and MCP-1 and augmented IFN-γ and IL-10 in the gastric mucosa of H. pylori-infected mice. The differential cytokine profile induced by Lf979C in H. pylori-infected mice correlated with an improved reduction in the pathogen gastric colonization and protection against inflammatory damage. The purified EPS of Lf979C reduced IL-8 and enhanced IL-10 levels in the gastric mucosa of infected mice, while no effect was observed for IFN-γ. This work demonstrates for the first time the in vivo ability of Lf979C to increase resistance against H. pylori infection by modulating the gastric innate immune response. In addition, we advanced knowledge of the mechanisms involved in the beneficial effects of Lf979C by demonstrating that its EPS is partially responsible for its immunomodulatory effect.

scholarly journals Robust Phagocyte Recruitment Controls the Opportunistic Fungal PathogenMucor circinelloidesin Innate GranulomasIn Vivo

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Sarah Inglesfield ◽  
Aleksandra Jasiulewicz ◽  
Matthew Hopwood ◽  
James Tyrrell ◽  
George Youlden ◽  
...  
Keyword(s):  
Immune Response ◽  
Fungal Infection ◽  
Real Time ◽  
Clinical Management ◽  
In Silico ◽  
Innate Immune ◽  
Granuloma Formation ◽  
Early Immune Response ◽  
Latent Stage

ABSTRACTMucormycosis is an emerging fungal infection with extremely high mortality rates in patients with defects in their innate immune response, specifically in functions mediated through phagocytes. However, we currently have a limited understanding of the molecular and cellular interactions between these innate immune effectors and mucormycete spores during the early immune response. Here, the early events of innate immune recruitment in response to infection byMucor circinelloidesspores are modeled by a combinedin silicomodeling approach and real-timein vivomicroscopy. Phagocytes are rapidly recruited to the site of infection in a zebrafish larval model of mucormycosis. This robust early recruitment protects from disease onsetin vivo.In silicoanalysis identified that protection is dependent on the number of phagocytes at the infection site, but not the speed of recruitment. The mathematical model highlights the role of proinflammatory signals for phagocyte recruitment and the importance of inhibition of spore germination for protection from active fungal disease. Thesein silicodata are supported by anin vivolack of fungal spore killing and lack of reactive oxygen burst, which together result in latent fungal infection. During this latent stage of infection, spores are controlled in innate granulomasin vivo. Disease can be reactivated by immunosuppression. Together, these data represent the firstin vivoreal-time analysis of innate granuloma formation during the early stages of a fungal infection. The results highlight a potential latent stage during mucormycosis that should urgently be considered for clinical management of patients.IMPORTANCEMucormycosis is a dramatic fungal infection frequently leading to the death of patients. We know little about the immune response to the fungus causing this infection, although evidence points toward defects in early immune events after infection. Here, we dissect this early immune response to infectious fungal spores. We show that specialized white blood cells (phagocytes) rapidly respond to these spores and accumulate around the fungus. However, we demonstrate that the mechanisms that enable phagocytes to kill the fungus fail, allowing for survival of spores. Instead a cluster of phagocytes resembling an early granuloma is formed around spores to control the latent infection. This study is the first detailed analysis of early granuloma formation during a fungal infection highlighting a latent stage that needs to be considered for clinical management of patients.

scholarly journals Coxiella burnetii Interaction with Neutrophils and MacrophagesIn Vitroand in SCID Mice following Aerosol Infection

2013 ◽  
Vol 81 (12) ◽  
pp. 4604-4614 ◽  
Author(s):  
Alexandra Elliott ◽  
Ying Peng ◽  
Guoquan Zhang
Keyword(s):  
Immune Response ◽  
Coxiella Burnetii ◽  
Q Fever ◽  
Natural Infection ◽  
Scid Mice ◽  
Innate Immune ◽  
Content Type ◽  
Aerosol Infection

ABSTRACTCoxiella burnetiiis an obligate intracellular bacterium that causes acute and chronic Q fever in humans. Human Q fever is mainly transmitted by aerosol infection. However, there is a fundamental gap in the knowledge regarding the mechanisms of pulmonary immunity againstC. burnetiiinfection. This study focused on understanding the interaction betweenC. burnetiiand innate immune cellsin vitroandin vivo. Both virulentC. burnetiiNine Mile phase I (NMI) and avirulent Nine Mile phase II (NMII) were able to infect neutrophils, while the infection rates were lower than 29%, suggesting thatC. burnetiican infect neutrophils, but infection is limited. Interestingly,C. burnetiiinside neutrophils can infect and replicate within macrophages, suggesting that neutrophils cannot killC. burnetiiandC. burnetiimay be using infection of neutrophils as an evasive strategy to infect macrophages. To elucidate the mechanisms of the innate immune response toC. burnetiinatural infection, SCID mice were exposed to aerosolizedC. burnetii. Surprisingly, neutrophil influx into the lungs was delayed until day 7 postinfection in both NMI- and NMII-infected mice. This result suggests that neutrophils may play a unique role in the early immune response against aerosolizedC. burnetii. Studying the interaction betweenC. burnetiiand the innate immune system can provide a model system for understanding how the bacteria evade early immune responses to cause infection.

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