Coinfection with an Intestinal Helminth Impairs Host Innate Immunity against Salmonella enterica Serovar Typhimurium and Exacerbates Intestinal Inflammation in Mice

ABSTRACTSalmonella entericaserovar Typhimurium is a Gram-negative food-borne pathogen that is a major cause of acute gastroenteritis in humans. The ability of the host to control such bacterial pathogens may be influenced by host immune status and by concurrent infections. Helminth parasites are of particular interest in this context because of their ability to modulate host immune responses and because their geographic distribution coincides with those parts of the world where infectious gastroenteritis is most problematic. To test the hypothesis that helminth infection may negatively regulate host mucosal innate immunity against bacterial enteropathogens, a murine coinfection model was established by using the intestinal nematodeHeligmosomoides polygyrusandS. Typhimurium. We found that mice coinfected withS. Typhimurium andH. polygyrusdeveloped more severe intestinal inflammation than animals infected withS. Typhimurium alone. The enhanced susceptibility toSalmonella-induced intestinal injury in coinfected mice was found to be associated with diminished neutrophil recruitment to the site of bacterial infection that correlated with decreased expression of the chemoattractants CXCL2/macrophage inflammatory protein 2 (MIP-2) and CXCL1/keratinocyte-derived chemokine (KC), poor control of bacterial replication, and exacerbated intestinal inflammation. The mechanism of helminth-induced inhibition of MIP-2 and KC expression involved interleukin-10 (IL-10) and, to a lesser extent, IL-4 and IL-13. Ly6G antibody-mediated depletion of neutrophils reproduced the adverse effects ofH. polygyrusonSalmonellainfection. Our results suggest that impaired neutrophil recruitment is an important contributor to the enhanced severity ofSalmonellaenterocolitis associated with helminth coinfection.

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Flagellin from Recombinant Attenuated Salmonella enterica Serovar Typhimurium Reveals a Fundamental Role in Chicken Innate Immunity

Clinical and Vaccine Immunology ◽

10.1128/cvi.05569-11 ◽

2012 ◽

Vol 19 (3) ◽

pp. 304-312 ◽

Cited By ~ 6

Author(s):

Zhiming Pan ◽

Qiuxia Cong ◽

Shizhong Geng ◽

Qiang Fang ◽

Xilong Kang ◽

...

Keyword(s):

Innate Immunity ◽

Immune Responses ◽

Salmonella Enterica ◽

Rational Design ◽

Bacterial Load ◽

Innate Immune ◽

Innate Immune Responses ◽

Content Type ◽

Serovar Typhimurium

ABSTRACTRecombinant attenuatedSalmonellavaccines have been extensively studied, with a focus on eliciting specific immune responses against foreign antigens. However, very little is known about the innate immune responses, particularly the role of flagellin, in the induction of innate immunity triggered by recombinant attenuatedSalmonellain chickens. In the present report, we describe twoSalmonella entericaserovar Typhimurium vaccine strains, wild-type (WT) or flagellin-deficient (flhD)Salmonella, both expressing the fusion protein (F) gene of Newcastle disease virus. We examined the bacterial load and spatiotemporal kinetics of expression of inflammatory cytokine, chemokine, and Toll-like receptor 5 (TLR5) genes in the cecum, spleen, liver, and heterophils following oral immunization of chickens with the twoSalmonellastrains. TheflhDmutant exhibited an enhanced ability to establish systemic infection compared to the WT. In contrast, the WT strain induced higher levels of interleukin-1β (IL-1β), CXCLi2, and TLR5 mRNAs in cecum, the spleen, and the heterophils than theflhDmutant at different times postinfection. Collectively, the present data reveal a fundamental role of flagellin in the innate immune responses induced by recombinant attenuatedSalmonellavaccines in chickens that should be considered for the rational design of novel vaccines for poultry.

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Neutrophils Are a Source of Gamma Interferon during Acute Salmonella enterica Serovar Typhimurium Colitis

Infection and Immunity ◽

10.1128/iai.01508-13 ◽

2014 ◽

Vol 82 (4) ◽

pp. 1692-1697 ◽

Cited By ~ 28

Author(s):

Alanna M. Spees ◽

Dawn D. Kingsbury ◽

Tamding Wangdi ◽

Mariana N. Xavier ◽

Renée M. Tsolis ◽

...

Keyword(s):

Salmonella Enterica ◽

Intestinal Inflammation ◽

Gamma Interferon ◽

Content Type ◽

Inflammatory Monocytes ◽

Intestinal Lesions ◽

Serovar Typhimurium ◽

Cellular Source ◽

Ifn Γ ◽

Cecal Mucosa

ABSTRACTGamma interferon (IFN-γ) is an important driver of intestinal inflammation during colitis caused bySalmonella entericaserovar Typhimurium. Here we used the mouse colitis model to investigate the cellular sources of IFN-γ in the cecal mucosa during the acute phase of anS. Typhimurium infection. While IFN-γ staining was detected in T cells, NK cells, and inflammatory monocytes at 2 days after infection, the majority of IFN-γ-positive cells in the cecal mucosa were neutrophils. Furthermore, neutrophil depletion blunted mucosalIfngexpression and reduced the severity of intestinal lesions duringS. Typhimurium infection. We conclude that neutrophils are a prominent cellular source of IFN-γ during the innate phase ofS. Typhimurium-induced colitis.

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The Actin-Polymerizing Activity of SipA Is Not Essential for Salmonella enterica Serovar Typhimurium-Induced Mucosal Inflammation

Infection and Immunity ◽

10.1128/iai.00337-12 ◽

2013 ◽

Vol 81 (5) ◽

pp. 1541-1549 ◽

Cited By ~ 7

Author(s):

Dongju Li ◽

Xueqin Wang ◽

Lu Wang ◽

Daoguo Zhou

Keyword(s):

Inflammatory Response ◽

Mouse Model ◽

Salmonella Enterica ◽

Intestinal Inflammation ◽

Host Cells ◽

Bacterial Invasion ◽

Content Type ◽

Type Iii ◽

Serovar Typhimurium ◽

Mouse Model Of Infection

ABSTRACTSalmonella entericaserovar Typhimurium depends on type III secretion systems to inject effector proteins into host cells to promote bacterial invasion and to induce intestinal inflammation. SipA, a type III effector, is known to play important roles in both the invasion and the elicitation of intestinal inflammation. The actin-modulating activity of SipA has been shown to promoteSalmonellaentry into epithelial cells. To investigate whether the actin-modulating activity of SipA is required for its ability to induce an inflammatory responsein vivo, we generated the SipAK635A E637Wmutant, which is deficient in actin-modulating activity.Salmonellastrains expressing the chromosomal SipAK635A E637Wpoint mutation had reduced invasion abilities but still caused colitis similar to that caused by the wild-type strain in a mouse model of infection. Our data indicate that the SipA actin-polymerizing activity is not essential for the SipA-induced inflammatory response in the mouse model of infection.

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Increased Susceptibility of Melanin-Concentrating Hormone-Deficient Mice to Infection with Salmonella enterica Serovar Typhimurium

Infection and Immunity ◽

10.1128/iai.00572-12 ◽

2012 ◽

Vol 81 (1) ◽

pp. 166-172 ◽

Cited By ~ 5

Author(s):

Apostolos K. A. Karagiannis ◽

Dimitrios C. Ziogas ◽

Beatriz Gras-Miralles ◽

Brenda M. Geiger ◽

Jutta Nagel ◽

...

Keyword(s):

Knockout Mice ◽

Salmonella Enterica ◽

Intestinal Inflammation ◽

Inflammatory Responses ◽

Peripheral Tissues ◽

Content Type ◽

Serovar Typhimurium ◽

Intestinal Pathogens ◽

Melanin Concentrating Hormone ◽

Deficient Mice

Melanin-concentrating hormone (MCH) was initially identified in mammals as a hypothalamic neuropeptide regulating appetite and energy balance. However, the wide distribution of MCH receptors in peripheral tissues suggests additional functions for MCH which remain largely unknown. We have previously reported that mice lacking MCH develop attenuated intestinal inflammation when exposed toClostridium difficiletoxin A. To further characterize the role of MCH in host defense mechanisms against intestinal pathogens,Salmonellaenterocolitis (usingSalmonella entericaserovar Typhimurium) was induced in MCH-deficient mice and their wild-type littermates. In the absence of MCH, infected mice had increased mortality associated with higher bacterial loads in blood, liver, and spleen. Moreover, the knockout mice developed more-severe intestinal inflammation, based on epithelial damage, immune cell infiltrates, and local and systemic cytokine levels. Paradoxically, these enhanced inflammatory responses in the MCH knockout mice were associated with disproportionally lower levels of macrophages infiltrating the intestine. Hence, we investigated potential direct effects of MCH on monocyte/macrophage functions critical for defense against intestinal pathogens. Using RAW 264.7 mouse monocytic cells, which express endogenous MCH receptor, we found that treatment with MCH enhanced the phagocytic capacity of these cells. Taken together, these findings reveal a previously unappreciated role for MCH in host-bacterial interactions.

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Toll-Like Receptor 2 (TLR2) and TLR9 Play Opposing Roles in Host Innate Immunity against Salmonella enterica Serovar Typhimurium Infection

Infection and Immunity ◽

10.1128/iai.02870-14 ◽

2015 ◽

Vol 83 (4) ◽

pp. 1641-1649 ◽

Cited By ~ 18

Author(s):

Renhui Zhan ◽

Qiuju Han ◽

Cai Zhang ◽

Zhigang Tian ◽

Jian Zhang

Keyword(s):

Innate Immunity ◽

Host Defense ◽

Salmonella Enterica ◽

Nk Cell ◽

Bacterial Load ◽

Content Type ◽

Serovar Typhimurium ◽

High Bacterial Load

Toll-like receptors (TLRs) are evolutionarily conserved host proteins that are essential for effective host defense against pathogens. However, recent studies suggest that some TLRs can negatively regulate immune responses. We observed here that TLR2 and TLR9 played opposite roles in regulating innate immunity against oral infection ofSalmonella entericaserovar Typhimurium in mice. WhileTLR9−/−mice exhibited shortened survival, an increased cytokine storm, and more severeSalmonellahepatitis than wild-type (WT) mice,TLR2−/−mice exhibited the opposite phenomenon. Further studies demonstrated that TLR2 deficiency and TLR9 deficiency in macrophages both disrupted NK cell cytotoxicity againstS. Typhimurium-infected macrophages by downregulating NK cell degranulation and gamma interferon (IFN-γ) production through decreased macrophage expression of the RAE-1 NKG2D ligand. But more importantly, we found thatS. Typhimurium-infectedTLR2−/−macrophages upregulated inducible nitric oxide synthase (iNOS) expression, resulting in a lower bacterial load than that in WT macrophagesin vitroand liversin vivoas well as low proinflammatory cytokine levels. In contrast,TLR9−/−macrophages showed decreased reactive oxygen species (ROS) expression concomitant with a high bacterial load in the macrophages and in livers ofTLR9−/−mice.TLR9−/−macrophages were also more susceptible than WT macrophages toS. Typhimurium-induced necroptosisin vitro, likely contributing to bacterial spread and transmissionin vivo. Collectively, these findings indicate that TLR2 negatively regulates anti-S. Typhimurium immunity, whereas TLR9 is vital to host defense and survival againstS. Typhimurium invasion. TLR2 antagonists or TLR9 agonists may thus serve as potential anti-S. Typhimurium therapeutic agents.

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Efficiency of Conditionally Attenuated Salmonella enterica Serovar Typhimurium in Bacterium-Mediated Tumor Therapy

mBio ◽

10.1128/mbio.00254-15 ◽

2015 ◽

Vol 6 (2) ◽

Cited By ~ 38

Author(s):

Michael Frahm ◽

Sebastian Felgner ◽

Dino Kocijancic ◽

Manfred Rohde ◽

Michael Hensel ◽

...

Keyword(s):

Salmonella Enterica ◽

Tumor Targeting ◽

Antitumor Effect ◽

Treatment Options ◽

Tumor Therapy ◽

Therapeutic Benefit ◽

Industrialized Countries ◽

Content Type ◽

Serovar Typhimurium ◽

Therapeutic Molecules

ABSTRACTIncreasing numbers of cancer cases generate a great urge for new treatment options. Applying bacteria likeSalmonella entericaserovar Typhimurium for cancer therapy represents an intensively explored option. These bacteria have been shown not only to colonize solid tumors but also to exhibit an intrinsic antitumor effect. In addition, they could serve as tumor-targeting vectors for therapeutic molecules. However, the pathogenicS. Typhimurium strains used for tumor therapy need to be attenuated for safe application. Here, lipopolysaccharide (LPS) deletion mutants (ΔrfaL, ΔrfaG, ΔrfaH, ΔrfaD, ΔrfaP, and ΔmsbBmutants) ofSalmonellawere investigated for efficiency in tumor therapy. Of such variants, the ΔrfaDand ΔrfaGdeep rough mutants exhibited the best tumor specificity and lowest pathogenicity. However, the intrinsic antitumor effect was found to be weak. To overcome this limitation, conditional attenuation was tested by complementing the mutants with an inducible arabinose promoter. The chromosomal integration of the respective LPS biosynthesis genes into thearaBADlocus exhibited the best balance of attenuation and therapeutic benefit. Thus, the present study establishes a basis for the development of an applicably cancer therapeutic bacterium.IMPORTANCECancer has become the second most frequent cause of death in industrialized countries. This and the drawbacks of routine therapies generate an urgent need for novel treatment options. Applying appropriately modifiedS. Typhimurium for therapy represents the major challenge of bacterium-mediated tumor therapy. In the present study, we demonstrated thatSalmonellabacteria conditionally modified in their LPS phenotype exhibit a safe tumor-targeting phenotype. Moreover, they could represent a suitable vehicle to shuttle therapeutic compounds directly into cancerous tissue without harming the host.

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A Salmonella Virulence Factor Activates the NOD1/NOD2 Signaling Pathway

mBio ◽

10.1128/mbio.00266-11 ◽

2011 ◽

Vol 2 (6) ◽

Cited By ~ 18

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.

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Whole-Genome Sequence of Salmonella enterica subsp. enterica Serovar Typhimurium Strain UPM 260, Isolated from a Broiler Chicken in Perak, Malaysia

Genome Announcements ◽

10.1128/genomea.01272-17 ◽

2017 ◽

Vol 5 (46) ◽

Author(s):

Najwa Syahirah Roslan ◽

Shagufta Jabeen ◽

Nurulfiza Mat Isa ◽

Abdul Rahman Omar ◽

Mohd Hair Bejo ◽

...

Keyword(s):

Genome Sequence ◽

Salmonella Enterica ◽

Broiler Chicken ◽

Whole Genome Sequence ◽

Whole Genome ◽

Content Type ◽

Typhimurium Strain ◽

Serovar Typhimurium

ABSTRACT Salmonella enterica subsp. enterica serovar Typhimurium is one of several well-categorized Salmonella serotypes recognized globally. Here, we report the whole-genome sequence of S. Typhimurium strain UPM 260, isolated from a broiler chicken.

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Association of a Protective Monoclonal IgA with the O Antigen of Salmonella enterica Serovar Typhimurium Impacts Type 3 Secretion and Outer Membrane Integrity

Infection and Immunity ◽

10.1128/iai.00018-12 ◽

2012 ◽

Vol 80 (7) ◽

pp. 2454-2463 ◽

Cited By ~ 22

Author(s):

Stephen J. Forbes ◽

Daniel Martinelli ◽

Chyongere Hsieh ◽

Jeffrey G. Ault ◽

Michael Marko ◽

...

Keyword(s):

Electron Microscopy ◽

Epithelial Cells ◽

Outer Membrane ◽

Salmonella Enterica ◽

Membrane Integrity ◽

Effector Proteins ◽

Content Type ◽

O Antigen ◽

Serovar Typhimurium ◽

Type 3

ABSTRACTInvasion of intestinal epithelial cells bySalmonella entericaserovar Typhimurium is an energetically demanding process, involving the transfer of effector proteins from invading bacteria into host cells via a specialized organelle known as theSalmonellapathogenicity island 1 (SPI-1) type 3 secretion system (T3SS). By a mechanism that remains poorly understood, entry ofS. Typhimurium into epithelial cells is inhibited by Sal4, a monoclonal, polymeric IgA antibody that binds an immunodominant epitope within the O-antigen (O-Ag) component of lipopolysaccharide. In this study, we investigated how the binding of Sal4 to the surface ofS. Typhimurium influences T3SS activity, bacterial energetics, and outer membrane integrity. We found that Sal4 treatment impaired T3SS-mediated translocon formation and attenuated the delivery of tagged effector proteins into epithelial cells. Sal4 treatment coincided with a partial reduction in membrane energetics and intracellular ATP levels, possibly explaining the impairment in T3SS activity. Sal4's effects on bacterial secretion and energetics occurred concurrently with an increase in O-Ag levels in culture supernatants, alterations in outer membrane permeability, and changes in surface ultrastructure, as revealed by transmission electron microscopy and cryo-electron microscopy. We propose that Sal4, by virtue of its ability to bind and cross-link the O-Ag, induces a form of outer membrane stress that compromises the integrity of theS. Typhimurium cell envelope and temporarily renders the bacterium avirulent.

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Draft Genome Sequence of Lactobacillus fermentum Lf2, an Exopolysaccharide-Producing Strain Isolated from Argentine Cheese

Microbiology Resource Announcements ◽

10.1128/mra.01072-18 ◽

2018 ◽

Vol 7 (18) ◽

Cited By ~ 2

Author(s):

Hugh M. B. Harris ◽

Elisa C. Ale ◽

Jorge A. Reinheimer ◽

Ana G. Binetti ◽

Paul W. O’Toole

Keyword(s):

Genome Sequence ◽

Salmonella Enterica ◽

Draft Genome ◽

Protective Role ◽

Lactobacillus Fermentum ◽

Draft Genome Sequence ◽

Content Type ◽

Serovar Typhimurium ◽

High Concentrations

Lactobacillus fermentum Lf2, an Argentine cheese isolate, can produce high concentrations of exopolysaccharides (EPS). These EPS were shown to improve the texture and rheology of yogurt, as well as to play a protective role in mice exposed to Salmonella enterica serovar Typhimurium.

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