scholarly journals Toll-Like Receptor 6 Plays an Important Role in Host Innate Resistance to Brucella abortus Infection in Mice

2013 ◽  
Vol 81 (5) ◽  
pp. 1654-1662 ◽  
Author(s):  
Leonardo A. de Almeida ◽  
Gilson C. Macedo ◽  
Fábio A. V. Marinho ◽  
Marco T. R. Gomes ◽  
Patrícia P. Corsetti ◽  
...  
Keyword(s):  
Immune Response ◽  
Dendritic Cells ◽  
Brucella Abortus ◽  
Proinflammatory Cytokine ◽  
Cytokine Production ◽  
Innate Immune ◽  
Proinflammatory Cytokine Production ◽  
Toll Like Receptor ◽  
Content Type

ABSTRACTBrucella abortusis recognized by several Toll-like receptor (TLR)-associated pathways triggering proinflammatory responses that affect both the nature and intensity of the immune response. Previously, we demonstrated thatB. abortus-mediated dendritic cell (DC) maturation and control of infection are dependent on the adaptor molecule MyD88. However, the involvement of all TLRs in response toB. abortusinfection is not completely understood. Therefore, we decided to evaluate the requirement for TLR6 in host resistance toB. abortus. Here, we demonstrated that TLR6 is an important component for triggering an innate immune response againstB. abortus. Anin vitroluciferase assay indicated that TLR6 cooperates with TLR2 to senseBrucellaand further activates NF-κB signaling. However,in vivoanalysis showed that TLR6, not TLR2, is required for the efficient control ofB. abortusinfection. Additionally,B. abortus-infected dendritic cells require TLR6 to induce tumor necrosis factor alpha (TNF-α) and interleukin-12 (IL-12). Furthermore, our findings demonstrated that the mitogen-activated protein kinase (MAPK) signaling pathway is impaired in TLR2, TLR6, and TLR2/6 knockout (KO) DCs when infected withB. abortus, which may account for the lower proinflammatory cytokine production observed in TLR6 KO mouse dendritic cells. In summary, the results presented here indicate that TLR6 is required to trigger innate immune responses againstB. abortusin vivoand is required for the full activation of DCs to induce robust proinflammatory cytokine production.

scholarly journals Analysis of the Human Mucosal Response to Cholera Reveals Sustained Activation of Innate Immune Signaling Pathways

2017 ◽  
Vol 86 (2) ◽  
Author(s):  
Daniel L. Bourque ◽  
Taufiqur Rahman Bhuiyan ◽  
Diane P. Genereux ◽  
Rasheduzzaman Rashu ◽  
Crystal N. Ellis ◽  
...  
Keyword(s):  
Gene Expression ◽  
Immune Response ◽  
Signaling Pathways ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Toll Like Receptor ◽  
Immune Signaling ◽  
Content Type ◽  
Upstream Regulators

ABSTRACTTo better understand the innate immune response toVibrio choleraeinfection, we tracked gene expression in the duodenal mucosa of 11 Bangladeshi adults with cholera, using biopsy specimens obtained immediately after rehydration and 30 and 180 days later. We identified differentially expressed genes and performed an analysis to predict differentially regulated pathways and upstream regulators. During acute cholera, there was a broad increase in the expression of genes associated with innate immunity, including activation of the NF-κB, mitogen-activated protein kinase (MAPK), and Toll-like receptor (TLR)-mediated signaling pathways, which, unexpectedly, persisted even 30 days after infection. Focusing on early differences in gene expression, we identified 37 genes that were differentially expressed on days 2 and 30 across the 11 participants. These genes included the endosomal Toll-like receptor geneTLR8, which was expressed in lamina propria cells. Underscoring a potential role for endosomal TLR-mediated signalingin vivo, our pathway analysis found that interferon regulatory factor 7 and beta 1 and alpha 2 interferons were among the top upstream regulators activated during cholera. Among the innate immune effectors, we found that the gene for DUOX2, an NADPH oxidase involved in the maintenance of intestinal homeostasis, was upregulated in intestinal epithelial cells during cholera. Notably, the observed increases inDUOX2andTLR8expression were also modeledin vitrowhen Caco-2 or THP-1 cells, respectively, were stimulated with liveV. choleraebut not with heat-killed organisms or cholera toxin alone. These previously unidentified features of the innate immune response toV. choleraeextend our understanding of the mucosal immune signaling pathways and effectors activatedin vivofollowing cholera.

scholarly journals Staphylococcus aureus ATP Synthase Promotes Biofilm Persistence by Influencing Innate Immunity

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Megan E. Bosch ◽  
Blake P. Bertrand ◽  
Cortney E. Heim ◽  
Abdulelah A. Alqarzaee ◽  
Sujata S. Chaudhari ◽  
...  
Keyword(s):  
Immune Response ◽  
Atp Synthase ◽  
Proinflammatory Cytokine ◽  
Cytokine Production ◽  
Joint Infection ◽  
Critical Role ◽  
Host Immune Response ◽  
Proinflammatory Cytokine Production ◽  
Content Type ◽  
Prosthetic Joint

ABSTRACT Staphylococcus aureus is a major cause of prosthetic joint infection (PJI), which is characterized by biofilm formation. S. aureus biofilm skews the host immune response toward an anti-inflammatory profile by the increased recruitment of myeloid-derived suppressor cells (MDSCs) that attenuate macrophage proinflammatory activity, leading to chronic infection. A screen of the Nebraska Transposon Mutant Library identified several hits in the ATP synthase operon that elicited a heightened inflammatory response in macrophages and MDSCs, including atpA, which encodes the alpha subunit of ATP synthase. An atpA transposon mutant (ΔatpA) had altered growth kinetics under both planktonic and biofilm conditions, along with a diffuse biofilm architecture that was permissive for leukocyte infiltration, as observed by confocal laser scanning microscopy. Coculture of MDSCs and macrophages with ΔatpA biofilm elicited significant increases in the proinflammatory cytokines interleukin 12p70 (IL-12p70), tumor necrosis factor alpha (TNF-α), and IL-6. This was attributed to increased leukocyte survival resulting from less toxin and protease production by ΔatpA biofilm as determined by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The enhanced inflammatory response elicited by ΔatpA biofilm was cell lysis-dependent since it was negated by polyanethole sodium sulfanate treatment or deletion of the major autolysin, Atl. In a mouse model of PJI, ΔatpA-infected mice had decreased MDSCs concomitant with increased monocyte/macrophage infiltrates and proinflammatory cytokine production, which resulted in biofilm clearance. These studies identify S. aureus ATP synthase as an important factor in influencing the immune response during biofilm-associated infection and bacterial persistence. IMPORTANCE Medical device-associated biofilm infections are a therapeutic challenge based on their antibiotic tolerance and ability to evade immune-mediated clearance. The virulence determinants responsible for bacterial biofilm to induce a maladaptive immune response remain largely unknown. This study identified a critical role for S. aureus ATP synthase in influencing the host immune response to biofilm infection. An S. aureus ATP synthase alpha subunit mutant (ΔatpA) elicited heightened proinflammatory cytokine production by leukocytes in vitro and in vivo, which coincided with improved biofilm clearance in a mouse model of prosthetic joint infection. The ability of S. aureus ΔatpA to augment host proinflammatory responses was cell lysis-dependent, as inhibition of bacterial lysis by polyanethole sodium sulfanate or a ΔatpAΔatl biofilm did not elicit heightened cytokine production. These studies reveal a critical role for AtpA in shaping the host immune response to S. aureus biofilm.

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 Glycolytic reprogramming of macrophages activated by NOD1 and TLR4 agonists: No association with proinflammatory cytokine production in normoxia

2020 ◽  
Vol 295 (10) ◽  
pp. 3099-3114
Author(s):  
Nina E. Murugina ◽  
Anna S. Budikhina ◽  
Yulia A. Dagil ◽  
Polina V. Maximchik ◽  
Lyudmila S. Balyasova ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Tumor Necrosis Factor ◽  
Proinflammatory Cytokine ◽  
Tumor Necrosis ◽  
Cytokine Production ◽  
Glucose Starvation ◽  
Proinflammatory Cytokine Production ◽  
Unfolded Protein ◽  
Protein Response ◽  
Necrosis Factor

Upon activation with pathogen-associated molecular patterns, metabolism of macrophages and dendritic cells is shifted from oxidative phosphorylation to aerobic glycolysis, which is considered important for proinflammatory cytokine production. Fragments of bacterial peptidoglycan (muramyl peptides) activate innate immune cells through nucleotide-binding oligomerization domain (NOD) 1 and/or NOD2 receptors. Here, we show that NOD1 and NOD2 agonists induce early glycolytic reprogramming of human monocyte-derived macrophages (MDM), which is similar to that induced by the Toll-like receptor 4 (TLR4) agonist lipopolysaccharide. This glycolytic reprogramming depends on Akt kinases, independent of mTOR complex 1 and is efficiently inhibited by 2-deoxy-d-glucose (2-DG) or by glucose starvation. 2-DG inhibits proinflammatory cytokine production by MDM and monocyte-derived dendritic cells activated by NOD1 or TLR4 agonists, except for tumor necrosis factor production by MDM, which is inhibited initially, but augmented 4 h after addition of agonists and later. However, 2-DG exerts these effects by inducing unfolded protein response rather than by inhibiting glycolysis. By contrast, glucose starvation does not cause unfolded protein response and, in normoxic conditions, only marginally affects proinflammatory cytokine production triggered through NOD1 or TLR4. In hypoxia mimicked by treating MDM with oligomycin (a mitochondrial ATP synthase inhibitor), both 2-DG and glucose starvation strongly suppress tumor necrosis factor and interleukin-6 production and compromise cell viability. In summary, the requirement of glycolytic reprogramming for proinflammatory cytokine production in normoxia is not obvious, and effects of 2-DG on cytokine responses should be interpreted cautiously. In hypoxia, however, glycolysis becomes critical for cytokine production and cell survival.

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