scholarly journals The Surface-Associated Exopolysaccharide of Bifidobacterium longum 35624 Plays an Essential Role in Dampening Host Proinflammatory Responses and Repressing Local TH17 Responses

2016 ◽  
Vol 82 (24) ◽  
pp. 7185-7196 ◽  
Author(s):  
Elisa Schiavi ◽  
Marita Gleinser ◽  
Evelyn Molloy ◽  
David Groeger ◽  
Remo Frei ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Cells ◽  
Essential Role ◽  
Inflammatory Responses ◽  
Bifidobacterium Longum ◽  
Molecular Characteristics ◽  
Interleukin 17 ◽  
Content Type ◽  
Exopolysaccharide Production

ABSTRACTThe immune-modulating properties of certain bifidobacterial strains, such asBifidobacterium longumsubsp.longum35624 (B. longum35624), have been well described, although the strain-specific molecular characteristics associated with such immune-regulatory activity are not well defined. It has previously been demonstrated thatB. longum35624 produces a cell surface exopolysaccharide (sEPS), and in this study, we investigated the role played by this exopolysaccharide in influencing the host immune response.B. longum35624 induced relatively low levels of cytokine secretion from human dendritic cells, whereas an isogenic exopolysaccharide-negative mutant derivative (termed sEPSneg) induced vastly more cytokines, including interleukin-17 (IL-17), and this response was reversed when exopolysaccharide production was restored in sEPSnegby genetic complementation. Administration ofB. longum35624 to mice of the T cell transfer colitis model prevented disease symptoms, whereas sEPSnegdid not protect against the development of colitis, with associated enhanced recruitment of IL-17+lymphocytes to the gut. Moreover, intranasal administration of sEPSnegalso resulted in enhanced recruitment of IL-17+lymphocytes to the murine lung. These data demonstrate that the particular exopolysaccharide produced byB. longum35624 plays an essential role in dampening proinflammatory host responses to the strain and that loss of exopolysaccharide production results in the induction of local TH17 responses.IMPORTANCEParticular gut commensals, such asB. longum35624, are known to contribute positively to the development of mucosal immune cells, resulting in protection from inflammatory diseases. However, the molecular basis and mechanisms for these commensal-host interactions are poorly described. In this report, an exopolysaccharide was shown to be decisive in influencing the immune response to the bacterium. We generated an isogenic mutant unable to produce exopolysaccharide and observed that this mutation caused a dramatic change in the response of human immune cellsin vitro. In addition, the use of mouse models confirmed that lack of exopolysaccharide production induces inflammatory responses to the bacterium. These results implicate the surface-associated exopolysaccharide of theB. longum35624 cell envelope in the prevention of aberrant inflammatory responses.

scholarly journals The Polysaccharide Capsule of Campylobacter jejuni Modulates the Host Immune Response

2012 ◽  
Vol 81 (3) ◽  
pp. 665-672 ◽  
Author(s):  
Alexander C. Maue ◽  
Krystle L. Mohawk ◽  
David K. Giles ◽  
Frédéric Poly ◽  
Cheryl P. Ewing ◽  
...  
Keyword(s):  
Immune Response ◽  
Campylobacter Jejuni ◽  
Diarrheal Disease ◽  
Host Immune Response ◽  
Interleukin 17 ◽  
Wild Type ◽  
Content Type ◽  
Polysaccharide Capsule ◽  
Colonization Model

ABSTRACTCampylobacter jejuniis a major cause of bacterial diarrheal disease worldwide. The organism is characterized by a diversity of polysaccharide structures, including a polysaccharide capsule. MostC. jejunicapsules are known to be decorated nonstoichiometrically with methyl phosphoramidate (MeOPN). The capsule ofC. jejuni81-176 has been shown to be required for serum resistance, but here we show that an encapsulated mutant lacking the MeOPN modification, anmpnCmutant, was equally as sensitive to serum killing as the nonencapsulated mutant. A nonencapsulated mutant, akpsMmutant, exhibited significantly reduced colonization compared to that of wild-type 81-176 in a mouse intestinal colonization model, and thempnCmutant showed an intermediate level of colonization. Both mutants were associated with higher levels of interleukin 17 (IL-17) expression from lamina propria CD4+cells than from cells from animals infected with 81-176. In addition, reduced levels of Toll-like receptor 4 (TLR4) and TLR2 activation were observed followingin vitrostimulation of human reporter cell lines with thekpsMandmpnCmutants compared to those with wild-type 81-176. The data suggest that the capsule polysaccharide ofC. jejuniand the MeOPN modification modulate the host immune response.

scholarly journals Contribution of Laccase Expression to Immune Response against Cryptococcus gattii Infection

2019 ◽  
Vol 88 (3) ◽  
Author(s):  
Adithap Hansakon ◽  
Popchai Ngamskulrungroj ◽  
Pornpimon Angkasekwinai
Keyword(s):  
Immune Response ◽  
Virulence Factor ◽  
Laccase Activity ◽  
Early Stage ◽  
Cryptococcus Gattii ◽  
Interleukin 17 ◽  
Neutrophil Accumulation ◽  
Content Type ◽  
Important Virulence Factor

ABSTRACT Cryptococcosis is an infectious disease caused by two fungal species, Cryptococcus neoformans and Cryptococcus gattii. While C. neoformans affects mainly immunocompromised patients, C. gattii infects both immunocompetent and immunocompromised individuals. Laccase is an important virulence factor that contributes to the virulence of C. neoformans by promoting pulmonary growth and dissemination to the brain. The presence of laccase in C. neoformans can shift the host immune response toward a nonprotective Th2-type response. However, the role of laccase in the immune response against C. gattii remains unclear. In this study, we characterized laccase activity in C. neoformans and C. gattii isolates from Thailand and investigated whether C. gattii that is deficient in laccase might modulate immune responses during infection. C. gattii was found to have higher laccase activity than C. neoformans, indicating the importance of laccase in the pathogenesis of C. gattii infection. The expression of laccase promoted intracellular proliferation in macrophages and inhibited in vitro fungal clearance. Mice infected with a lac1Δ mutant strain of C. gattii had reduced lung burdens at the early but not the late stage of infection. Without affecting type-1 and type-2 responses, the deficiency of laccase in C. gattii induced cryptococcus-specific interleukin-17 (IL-17) cytokine, neutrophil accumulation, and expression of the neutrophil-associated cytokine gene Csf3 and chemokine genes Cxcl1, Cxcl2, and Cxcl5 in vivo, as well as enhanced neutrophil-mediated phagocytosis and killing in vitro. Thus, our data suggest that laccase constitutes an important virulence factor of C. gattii that plays roles in attenuating Th17-type immunity, neutrophil recruitment, and function during the early stage of infection.

scholarly journals A Salmonella Virulence Factor Activates the NOD1/NOD2 Signaling Pathway

mBio ◽  
2011 ◽  
Vol 2 (6) ◽  
Author(s):  
A. Marijke Keestra ◽  
Maria G. Winter ◽  
Daisy Klein-Douwel ◽  
Mariana N. Xavier ◽  
Sebastian E. Winter ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Intestinal Inflammation ◽  
Inflammatory Responses ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Content Type ◽  
Type Iii

ABSTRACTThe invasion-associated type III secretion system (T3SS-1) ofSalmonella entericaserotype Typhimurium (S. Typhimurium) activates the transcription factor NF-κB in tissue culture cells and induces inflammatory responses in animal models through unknown mechanisms. Here we show that bacterial delivery or ectopic expression of SipA, a T3SS-1-translocated protein, led to the activation of the NOD1/NOD2 signaling pathway and consequent RIP2-mediated induction of NF-κB-dependent inflammatory responses. SipA-mediated activation of NOD1/NOD2 signaling was independent of bacterial invasionin vitrobut required an intact T3SS-1. In the mouse colitis model, SipA triggered mucosal inflammation in wild-type mice but not in NOD1/NOD2-deficient mice. These findings implicate SipA-driven activation of the NOD1/NOD2 signaling pathway as a mechanism by which the T3SS-1 induces inflammatory responsesin vitroandin vivo.IMPORTANCESalmonella entericaserotype Typhimurium (S. Typhimurium) deploys a type III secretion system (T3SS-1) to induce intestinal inflammation and benefits from the ensuing host response, which enhances growth of the pathogen in the intestinal lumen. However, the mechanisms by which the T3SS-1 triggers inflammatory responses have not been resolved. Here we show that the T3SS-1 effector protein SipA induces NF-κB activation and intestinal inflammation by activating the NOD1/NOD2 signaling pathway. These data suggest that the T3SS-1 escalates innate responses through a SipA-mediated activation of pattern recognition receptors in the host cell cytosol.

scholarly journals DAP12 Inhibits Pulmonary Immune Responses to Cryptococcus neoformans

2016 ◽  
Vol 84 (6) ◽  
pp. 1879-1886 ◽  
Author(s):  
Lena J. Heung ◽  
Tobias M. Hohl
Keyword(s):  
Immune Response ◽  
Nk Cells ◽  
Cryptococcus Neoformans ◽  
Molecular Mechanisms ◽  
Content Type ◽  
Effector Cells ◽  
Opportunistic Fungal Pathogen ◽  
Efficient Uptake ◽  
Bacteria And Fungi

Cryptococcus neoformansis an opportunistic fungal pathogen that is inhaled into the lungs and can lead to life-threatening meningoencephalitis in immunocompromised patients. Currently, the molecular mechanisms that regulate the mammalian immune response to respiratory cryptococcal challenge remain poorly defined. DAP12, a signaling adapter for multiple pattern recognition receptors in myeloid and natural killer (NK) cells, has been shown to play both activating and inhibitory roles during lung infections by different bacteria and fungi. In this study, we demonstrate that DAP12 plays an important inhibitory role in the immune response toC. neoformans. Infectious outcomes in DAP12−/−mice, including survival and lung fungal burden, are significantly improved compared to those in C57BL/6 wild-type (WT) mice. We find that eosinophils and macrophages are decreased while NK cells are increased in the lungs of infected DAP12−/−mice. In contrast to WT NK cells, DAP12−/−NK cells are able to repressC. neoformansgrowthin vitro. Additionally, DAP12−/−macrophages are more highly activated than WT macrophages, with increased production of tumor necrosis factor (TNF) and CCL5/RANTES and more efficient uptake and killing ofC. neoformans. These findings suggest that DAP12 acts as a brake on the pulmonary immune response toC. neoformansby promoting pulmonary eosinophilia and by inhibiting the activation and antifungal activities of effector cells, including NK cells and macrophages.

scholarly journals Regulatory T Cells Contribute to Resistance against Lyme Arthritis

2020 ◽  
Vol 88 (11) ◽  
Author(s):  
Emily M. Siebers ◽  
Elizabeth S. Liedhegner ◽  
Michael W. Lawlor ◽  
Ronald F. Schell ◽  
Dean T. Nardelli
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lyme Disease ◽  
Regulatory T Cells ◽  
Regulatory T Cell ◽  
Interleukin 10 ◽  
Lyme Arthritis ◽  
Interleukin 17 ◽  
Content Type

ABSTRACT The symptoms of Lyme disease are caused by inflammation induced by species of the Borrelia burgdorferi sensu lato complex. The various presentations of Lyme disease in the population suggest that differences exist in the intensity and regulation of the host response to the spirochete. Previous work has described correlations between the presence of regulatory T cells and recovery from Lyme arthritis. However, the effects of Foxp3-expressing CD4+ T cells existing prior to, and during, B. burgdorferi infection have not been well characterized. Here, we used C57BL/6 “depletion of regulatory T cell” mice to assess the effects these cells have on the arthritis-resistant phenotype characteristic of this mouse strain. We showed that depletion of regulatory T cells prior to infection with B. burgdorferi resulted in sustained swelling, as well as histopathological changes, of the tibiotarsal joints that were not observed in infected control mice. Additionally, in vitro stimulation of splenocytes from these regulatory T cell-depleted mice resulted in increases in gamma interferon and interleukin-17 production and decreases in interleukin-10 production that were not evident among splenocytes of infected mice in which Treg cells were not depleted. Depletion of regulatory T cells at various times after infection also induced rapid joint swelling. Collectively, these findings provide evidence that regulatory T cells existing at the time of, and possibly after, B. burgdorferi infection may play an important role in limiting the development of arthritis.

scholarly journals Tim-3 Induces Th2-Biased Immunity and Alternative Macrophage Activation during Schistosoma japonicum Infection

2015 ◽  
Vol 83 (8) ◽  
pp. 3074-3082 ◽  
Author(s):  
Nan Hou ◽  
Xianyu Piao ◽  
Shuai Liu ◽  
Chuang Wu ◽  
Qijun Chen
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Schistosoma Japonicum ◽  
Immune Cell ◽  
Nk Cell ◽  
Alternative Activation ◽  
Interleukin 12 ◽  
Content Type

T cell immunoglobulin- and mucin-domain-containing molecule 3 (Tim-3) has been regarded as an important regulatory factor in both adaptive and innate immunity. Recently, Tim-3 was reported to be involved in Th2-biased immune responses in mice infected withSchistosoma japonicum, but the exact mechanism behind the involvement of Tim-3 remains unknown. The present study aims to understand the role of Tim-3 in the immune response againstS. japonicuminfection. Tim-3 expression was determined by flow cytometry, and increased Tim-3 expression was observed on CD4+and CD8+T cells, NK1.1+cells, and CD11b+cells from the livers ofS. japonicum-infected mice. However, the increased level of Tim-3 was lower in the spleen than in the liver, and no increase in Tim-3 expression was observed on splenic CD8+T cells or CD11b+cells. The schistosome-induced upregulation of Tim-3 on natural killer (NK) cells was accompanied by reduced NK cell numbersin vitroandin vivo. Tim-3 antibody blockade led to upregulation of inducible nitric oxide synthase and interleukin-12 (IL-12) mRNA in CD11b+cells cocultured with soluble egg antigen and downregulation of Arg1 and IL-10, which are markers of M2 macrophages. In summary, we observed schistosome-induced expression of Tim-3 on critical immune cell populations, which may be involved in the Th2-biased immune response and alternative activation of macrophages during 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 A Novel Combination of Vitamin C, Curcumin and Glycyrrhizic Acid Potentially Regulates Immune and Inflammatory Response Associated with Coronavirus Infections: A Perspective from System Biology Analysis

Nutrients ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1193 ◽  
Author(s):  
Liang Chen ◽  
Chun Hu ◽  
Molly Hood ◽  
Xue Zhang ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Immune Response ◽  
Vitamin C ◽  
Inflammatory Response ◽  
Signaling Pathways ◽  
System Biology ◽  
Glycyrrhizic Acid ◽  
Inflammatory Responses ◽  
Mapk Signaling ◽  
Gene Target

Novel coronaviruses (CoV) have emerged periodically around the world in recent years. The recurrent spreading of CoVs imposes an ongoing threat to global health and the economy. Since no specific therapy for these CoVs is available, any beneficial approach (including nutritional and dietary approach) is worth investigation. Based on recent advances in nutrients and phytonutrients research, a novel combination of vitamin C, curcumin and glycyrrhizic acid (VCG Plus) was developed that has potential against CoV infection. System biology tools were applied to explore the potential of VCG Plus in modulating targets and pathways relevant to immune and inflammation responses. Gene target acquisition, gene ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment were conducted consecutively along with network analysis. The results show that VCG Plus can act on 88 hub targets which are closely connected and associated with immune and inflammatory responses. Specifically, VCG Plus has the potential to regulate innate immune response by acting on NOD-like and Toll-like signaling pathways to promote interferons production, activate and balance T-cells, and regulate the inflammatory response by inhibiting PI3K/AKT, NF-κB and MAPK signaling pathways. All these biological processes and pathways have been well documented in CoV infections studies. Therefore, our findings suggest that VCG Plus may be helpful in regulating immune response to combat CoV infections and inhibit excessive inflammatory responses to prevent the onset of cytokine storm. However, further in vitro and in vivo experiments are warranted to validate the current findings with system biology tools. Our current approach provides a new strategy in predicting formulation rationale when developing new dietary supplements.

scholarly journals Identification of Pathogen Genomic Differences That Impact Human Immune Response and Disease during Cryptococcus neoformans Infection

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Aleeza C. Gerstein ◽  
Katrina M. Jackson ◽  
Tami R. McDonald ◽  
Yina Wang ◽  
Benjamin D. Lueck ◽  
...  
Keyword(s):  
Immune Response ◽  
Cryptococcus Neoformans ◽  
Candidate Genes ◽  
Cryptococcal Meningitis ◽  
Human Disease ◽  
Whole Genome ◽  
Content Type ◽  
Future Studies ◽  
Human Survival

ABSTRACT Patient outcomes during infection are due to a complex interplay between the quality of medical care, host immunity factors, and the infecting pathogen’s characteristics. To probe the influence of pathogen genotype on human survival, immune response, and other parameters of disease, we examined Cryptococcus neoformans isolates collected during the Cryptococcal Optimal Antiretroviral Therapy (ART) Timing (COAT) Trial in Uganda. We measured human participants’ survival, meningitis disease parameters, immunologic phenotypes, and pathogen in vitro growth characteristics. We compared those clinical data to whole-genome sequences from 38 C. neoformans isolates of the most frequently observed sequence type (ST), ST93, in our Ugandan participant population and to sequences from an additional 18 strains of 9 other sequence types representing the known genetic diversity within the Ugandan Cryptococcus clinical isolates. We focused our analyses on 652 polymorphisms that were variable among the ST93 genomes, were not in centromeres or extreme telomeres, and were predicted to have a fitness effect. Logistic regression and principal component analysis identified 40 candidate Cryptococcus genes and 3 hypothetical RNAs associated with human survival, immunologic response, or clinical parameters. We infected mice with 17 available KN99α gene deletion strains for these candidate genes and found that 35% (6/17) directly influenced murine survival. Four of the six gene deletions that impacted murine survival were novel. Such bedside-to-bench translational research identifies important candidate genes for future studies on virulence-associated traits in human Cryptococcus infections. IMPORTANCE Even with the best available care, mortality rates in cryptococcal meningitis range from 20% to 60%. Disease is often due to infection by the fungus Cryptococcus neoformans and involves a complex interaction between the human host and the fungal pathogen. Although previous studies have suggested genetic differences in the pathogen impact human disease, it has proven quite difficult to identify the specific C. neoformans genes that impact the outcome of the human infection. Here, we take advantage of a Ugandan patient cohort infected with closely related C. neoformans strains to examine the role of pathogen genetic variants on several human disease characteristics. Using a pathogen whole-genome sequencing approach, we showed that 40 C. neoformans genes are associated with human disease. Surprisingly, many of these genes are specific to Cryptococcus and have unknown functions. We also show deletion of some of these genes alters disease in a mouse model of infection, confirming their role in disease. These findings are particularly important because they are the first to identify C. neoformans genes associated with human cryptococcal meningitis and lay the foundation for future studies that may lead to new treatment strategies aimed at reducing patient mortality.

scholarly journals Dual-Wavelength Photosensitive Nano-in-Micro Scaffold Regulates Innate and Adaptive Immune Responses for Osteogenesis

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Qin Zhao ◽  
Miusi Shi ◽  
Chengcheng Yin ◽  
Zifan Zhao ◽  
Jinglun Zhang ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Immune Cells ◽  
Inflammatory Responses ◽  
Macrophage Polarization ◽  
T Cell Response ◽  
Dual Wavelength ◽  
M2 Macrophage ◽  
Adaptive Immune Responses ◽  
Adaptive Immune

AbstractThe immune response of a biomaterial determines its osteoinductive effect. Although the mechanisms by which some immune cells promote regeneration have been revealed, the biomaterial-induced immune response is a dynamic process involving multiple cells. Currently, it is challenging to accurately regulate the innate and adaptive immune responses to promote osteoinduction in biomaterials. Herein, we investigated the roles of macrophages and dendritic cells (DCs) during the osteoinduction of biphasic calcium phosphate (BCP) scaffolds. We found that osteoinductive BCP directed M2 macrophage polarization and inhibited DC maturation, resulting in low T cell response and efficient osteogenesis. Accordingly, a dual-targeting nano-in-micro scaffold (BCP loaded with gold nanocage, BCP-GNC) was designed to regulate the immune responses of macrophages and DCs. Through a dual-wavelength photosensitive switch, BCP-GNC releases interleukin-4 in the early stage of osteoinduction to target M2 macrophages and then releases dexamethasone in the later stage to target immature DCs, creating a desirable inflammatory environment for osteogenesis. This study demonstrates that biomaterials developed to have specific regulatory capacities for immune cells can be used to control the early inflammatory responses of implanted materials and induce osteogenesis.

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