scholarly journals Genetic Mechanisms Underlying the Pathogenicity of Cold-Stressed Salmonella enterica Serovar Typhimurium in Cultured Intestinal Epithelial Cells

2014 ◽  
Vol 80 (22) ◽  
pp. 6943-6953 ◽  
Author(s):  
Jigna Shah ◽  
Prerak T. Desai ◽  
Bart C. Weimer
Keyword(s):  
Epithelial Cells ◽  
Host Cell ◽  
Intestinal Epithelial Cells ◽  
Acid Stress ◽  
Intestinal Epithelial ◽  
Cell Infection ◽  
Antioxidant Genes ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Adhesion And Invasion

ABSTRACTSalmonellaencounters various stresses in the environment and in the host during infection. The effects of cold (5°C, 48 h), peroxide (5 mM H2O2, 5 h) and acid stress (pH 4.0, 90 min) were tested on pathogenicity ofSalmonella. Prior exposure ofSalmonellato cold stress significantly (P< 0.05) increased adhesion and invasion of cultured intestinal epithelial (Caco-2) cells. This increasedSalmonella-host cell association was also correlated with significant induction of several virulence-associated genes, implying an increased potential of cold-stressedSalmonellato cause an infection. In Caco-2 cells infected with cold-stressedSalmonella, genes involved in the electron transfer chain were significantly induced, but no simultaneous significant increase in expression of antioxidant genes that neutralize the effect of superoxide radicals or reactive oxygen species was observed. Increased production of caspase 9 and caspase 3/7 was confirmed during host cell infection with cold-stressedSalmonella. Further, a prophage gene,STM2699, induced in cold-stressedSalmonellaand a spectrin gene, SPTAN1, induced inSalmonella-infected intestinal epithelial cells were found to have a significant contribution in increased adhesion and invasion of cold-stressedSalmonellain epithelial cells.

scholarly journals Salmonella enterica serovar Typhimurium chitinases modulate the intestinal glycome and promote small intestinal invasion

2021 ◽  
Author(s):  
Jason R Devlin ◽  
William Santus ◽  
Jorge Mendez ◽  
Wenjing Peng ◽  
Aiying Yu ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Virulence Factors ◽  
Salmonella Enterica ◽  
Intestinal Epithelial Cells ◽  
Bacterial Species ◽  
Intestinal Epithelial ◽  
Food Borne ◽  
Serovar Typhimurium ◽  
Small Intestinal ◽  
Adhesion And Invasion

AbstractSalmonella enterica serovar Typhimurium (Salmonella) is one of the leading causes of food-borne illnesses worldwide. To colonize the gastrointestinal tract, Salmonella produces multiple virulence factors that facilitate cellular invasion. Chitinases have been recently emerging as virulence factors for various pathogenic bacterial species and the Salmonella genome contains two annotated chitinases: STM0018 (chiA) and STM0233. However, the role of these chitinases during Salmonella pathogenesis is unknown. The putative chitinase STM0233 has not been studied previously and only limited data exists on ChiA. Chitinases typically hydrolyze chitin polymers, which are absent in vertebrates. However, chiA expression was detected in infection models and purified ChiA cleaved carbohydrate subunits present on mammalian surface glycoproteins, indicating a role during pathogenesis. Here, we demonstrate that expression of chiA and STM0233 is upregulated in the mouse gut and that both chitinases facilitate epithelial cell adhesion and invasion. Salmonella lacking both chitinases showed a 70% reduction in invasion of small intestinal epithelial cells in vitro. In a gastroenteritis mouse model, chitinase-deficient Salmonella strains were also significantly attenuated in the invasion of small intestinal tissue. This reduced invasion resulted in significantly delayed Salmonella dissemination to the spleen and the liver, but chitinases were not required for systemic survival. The invasion defect of the chitinase-deficient strain was rescued by the presence of wild-type Salmonella, suggesting that chitinases are secreted. By analyzing N-linked glycans of small intestinal cells, we identified specific N-acetylglucosamine-containing glycans as potential extracellular targets of Salmonella chitinases. This analysis also revealed differential abundance of Lewis X-containing glycans that is likely a result of host cell modulation due to the detection of Salmonella chitinases. Similar glycomic changes elicited by chitinase deficient strains indicate functional redundancy of the chitinases. Overall, our results demonstrate that Salmonella chitinases contribute to intestinal adhesion and invasion through modulation of the host glycome.Author SummarySalmonella Typhimurium infection is one of the leading causes of food-borne illnesses worldwide. In order for Salmonella to effectively cause disease, it has to invade the epithelial cells lining the intestinal tract. This invasion step allows Salmonella to replicate efficiently, causing further tissue damage and inflammation. In susceptible patients, Salmonella can spread past the intestines and infect peripheral organs. It is essential to fully understand the invasion mechanism used by Salmonella to design better treatments for infection. Here, we demonstrate that the two chitinases produced by Salmonella are involved in this invasion process. We show that Salmonella chitinases interact with surface glycans of intestinal epithelial cells and promote adhesion and invasion. Using a mouse infection model, we show that Salmonella chitinases are required for the invasion of the small intestine and enhance the dissemination of Salmonella to other organs. This study reveals an additional mechanism by which Salmonella invades and causes infection.

scholarly journals Salmonella entericaSerovar Typhimurium Increases Functional PD-L1 Synergistically with Gamma Interferon in Intestinal Epithelial Cells viaSalmonellaPathogenicity Island 2

2018 ◽  
Vol 86 (5) ◽  
pp. e00674-17 ◽  
Author(s):  
J. M. Sahler ◽  
C. R. Eade ◽  
C. Altier ◽  
J. C. March
Keyword(s):  
T Cells ◽  
Epithelial Cells ◽  
Host Cell ◽  
Immune Evasion ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Activated T Cells ◽  
Content Type ◽  
Ifn Γ ◽  
First Time

ABSTRACTNontyphoidal serovars ofSalmonella entericaare pathogenic bacteria that are common causes of food poisoning. WhereasSalmonellamechanisms of host cell invasion, inflammation, and pathogenesis are mostly well established, a new possible mechanism of immune evasion is being uncovered. Programmed death ligand 1 (PD-L1) is an immunosuppressive membrane protein that binds to activated T cells via their PD-1 receptor and thereby halts their activation. PD-L1 expression plays an essential role in the immunological tolerance of self-antigens but is also exploited for immune evasion by pathogen-infected cells and cancer cells. Here, we show for the first time thatSalmonellainfection of intestinal epithelial cells causes the induction of PD-L1. The increased expression of PD-L1 throughSalmonellainfection was seen in both human and rat intestinal epithelial cell lines. We determined that cellular invasion by the bacteria is necessary for PD-L1 induction, potentially indicating thatSalmonellastrains are delivering mediators from inside the host cell that trigger the increased PD-L1 expression. Using knockout mutants, we determined that this effect largely originates from theSalmonellapathogenicity island 2. We also show for the first time in any cell type thatSalmonellacombined with gamma interferon (IFN-γ) causes a synergistic induction of PD-L1. Finally, we show thatSalmonellaplus IFN-γ induction of PD-L1 decreased the cytokine production of activated T cells. UnderstandingSalmonellaimmune evasion strategies could generate new therapeutic targets and help to manipulate PD-L1 expression in other diseases.

scholarly journals Dual Recognition of Sialic Acid and αGal Epitopes by the VP8* Domains of the Bovine Rotavirus G6P[5] WC3 and of Its Mono-reassortant G4P[5] RotaTeq Vaccine Strains

2019 ◽  
Vol 93 (18) ◽  
Author(s):  
Mia Madel Alfajaro ◽  
Ji-Yun Kim ◽  
Laure Barbé ◽  
Eun-Hyo Cho ◽  
Jun-Gyu Park ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Blood Group ◽  
Intestinal Epithelial Cells ◽  
Sialic Acids ◽  
Blood Group Antigens ◽  
Intestinal Epithelial ◽  
Content Type ◽  
Group A Rotaviruses ◽  
Group A ◽  
Small Intestinal

ABSTRACTGroup A rotaviruses, an important cause of severe diarrhea in children and young animals, initiate infection via interactions of the VP8* domain of the VP4 spike protein with cell surface sialic acids (SAs) or histo-blood group antigens (HBGAs). Although the bovine G6P[5] WC3 strain is an important animal pathogen and is also used in the bovine-human reassortant RotaTeq vaccine, the receptor(s) for the VP8* domain of WC3 and its reassortant strains have not yet been identified. In the present study, HBGA- and saliva-binding assays showed that both G6P[5] WC3 and mono-reassortant G4P[5] strains recognized the αGal HBGA. The infectivity of both P[5]-bearing strains was significantly reduced in αGal-free MA-104 cells by pretreatment with a broadly specific neuraminidase or by coincubation with the α2,6-linked SA-specificSambucus nigralectin, but not by the α2,3-linked specific sialidase or byMaackia amurensislectin. Free NeuAc and the αGal trisaccharide also prevented the infectivity of both strains. This indicated that both P[5]-bearing strains utilize α2,6-linked SA as a ligand on MA104 cells. However, the two strains replicated in differentiated bovine small intestinal enteroids and in their human counterparts that lack α2,6-linked SA or αGal HBGA, suggesting that additional or alternative receptors such as integrins, hsp70, and tight-junction proteins bound directly to the VP5* domain can be used by the P[5]-bearing strains to initiate the infection of human cells. In addition, these data also suggested that P[5]-bearing strains have potential for cross-species transmission.IMPORTANCEGroup A rotaviruses initiate infection through the binding of the VP8* domain of the VP4 protein to sialic acids (SAs) or histo-blood group antigens (HBGAs). Although the bovine G6P[5] WC3 strain is an important animal pathogen and is used as the backbone in the bovine-human reassortant RotaTeq vaccine, the receptor(s) for their P[5] VP8* domain has remained elusive. Using a variety of approaches, we demonstrated that the WC3 and bovine-human mono-reassortant G4P[5] vaccine strains recognize both α2,6-linked SA and αGal HBGA as ligands. Neither ligand is expressed on human small intestinal epithelial cells, explaining the absence of natural human infection by P[5]-bearing strains. However, we observed that the P[5]-bearing WC3 and G4P[5] RotaTeq vaccine strains could still infect human intestinal epithelial cells. Thus, the four P[5] RotaTeq vaccine strains potentially binding to additional alternative receptors may be efficient and effective in providing protection against severe rotavirus disease in human.

OmpD but not OmpC is involved in adherence ofSalmonella entericaserovar Typhimurium to human cells

2004 ◽  
Vol 50 (9) ◽  
pp. 719-727 ◽  
Author(s):  
Bochiwe Hara-Kaonga ◽  
Thomas G Pistole
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Human Cells ◽  
Host Cells ◽  
Intestinal Epithelial ◽  
Wild Type ◽  
Human Macrophages ◽  
Significant Difference ◽  
Serovar Typhimurium

Conflicting reports exist regarding the role of porins OmpC and OmpD in infections due to Salmonella enterica serovar Typhimurium. This study investigated the role of these porins in bacterial adherence to human macrophages and intestinal epithelial cells. ompC and ompD mutant strains were created by transposon mutagenesis using P22-mediated transduction of Tn10 and Tn5 insertions, respectively, into wild-type strain 14028. Fluorescein-labeled wild-type and mutant bacteria were incubated with host cells at various bacteria to cell ratios for 1 h at 37 °C and analyzed by flow cytometry. The mean fluorescence intensity of cells with associated wild-type and mutant bacteria was used to estimate the number of bacteria bound per host cell. Adherence was also measured by fluorescence microscopy. Neither assay showed a significant difference in binding of the ompC mutant and wild-type strains to the human cells. In contrast, the ompD mutant exhibited lowered binding to both cell types. Our findings suggest that OmpD but not OmpC is involved in the recognition of Salmonella serovar Typhimurium by human macrophages and intestinal epithelial cells.Key words: Salmonella, adherence, porins, intestinal epithelial cells, macrophage.

scholarly journals Interleukin-7 Produced by Intestinal Epithelial Cells in Response to Citrobacter rodentium Infection Plays a Major Role in Innate Immunity against This Pathogen

2015 ◽  
Vol 83 (8) ◽  
pp. 3213-3223 ◽  
Author(s):  
Wei Zhang ◽  
Jiang-Yuan Du ◽  
Qing Yu ◽  
Jun-O Jin
Keyword(s):  
Epithelial Cells ◽  
Protective Immunity ◽  
Bacterial Infections ◽  
Intestinal Epithelial Cells ◽  
Intestinal Damage ◽  
Intestinal Epithelial ◽  
Citrobacter Rodentium ◽  
Content Type ◽  
Interleukin 7

Interleukin-7 (IL-7) engages multiple mechanisms to overcome chronic viral infections, but the role of IL-7 in bacterial infections, especially enteric bacterial infections, remains unclear. Here we characterized the previously unexplored role of IL-7 in the innate immune response to the attaching and effacing bacteriumCitrobacter rodentium.C. rodentiuminfection induced IL-7 production from intestinal epithelial cells (IECs). IL-7 production from IECs in response toC. rodentiumwas dependent on gamma interferon (IFN-γ)-producing NK1.1+cells and IL-12. Treatment with anti-IL-7Rα antibody duringC. rodentiuminfection resulted in a higher bacterial burden, enhanced intestinal damage, and greater weight loss and mortality than observed with the control IgG treatment. IEC-produced IL-7 was only essential for protective immunity againstC. rodentiumduring the first 6 days after infection. An impaired bacterial clearance upon IL-7Rα blockade was associated with a significant decrease in macrophage accumulation and activation in the colon. Moreover,C. rodentium-induced expansion and activation of intestinal CD4+lymphoid tissue inducer (LTi) cells was completely abrogated by IL-7Rα blockade. Collectively, these data demonstrate that IL-7 is produced by IECs in response toC. rodentiuminfection and plays a critical role in the protective immunity against this intestinal attaching and effacing bacterium.

scholarly journals CapC, a Novel Autotransporter and Virulence Factor ofCampylobacter jejuni

2018 ◽  
Vol 84 (16) ◽  
Author(s):  
Jai W. Mehat ◽  
Simon F. Park ◽  
Arnoud H. M. van Vliet ◽  
Roberto M. La Ragione
Keyword(s):  
Public Health ◽  
Epithelial Cells ◽  
Campylobacter Jejuni ◽  
Virulence Factor ◽  
Causative Agent ◽  
Galleria Mellonella ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Content Type ◽  
Reduced Adherence

ABSTRACTCampylobacter jejuniis recognized as an important causative agent of bacterial gastroenteritis in the developed world. Despite the identification of several factors contributing to infection, characterization of the virulence strategies employed byC. jejuniremains a significant challenge. Bacterial autotransporter proteins are a major class of secretory proteins in Gram-negative bacteria, and notably, many autotransporter proteins contribute to bacterial virulence. The aim of this study was to characterize theC. jejuni81116 C8J_1278 gene (capC), predicted to encode an autotransporter protein, and examine the contribution of this factor to virulence ofC. jejuni. The predicted CapC protein has a number of features that are consistent with autotransporters, including the N-terminal signal sequence and the C-terminal β-barrel domain and was determined to localize to the outer membrane. Inactivation of thecapCgene inC. jejuni81116 andC. jejuniM1 resulted in reduced insecticidal activity inGalleria mellonellalarvae. Furthermore,C. jejuni capCmutants displayed significantly reduced adherence to and invasion of nonpolarized, partially differentiated Caco-2 and T84 intestinal epithelial cells. Gentamicin treatment showed that the reduced invasion of thecapCmutant is primarily caused by reduced adherence to intestinal epithelial cells, not by reduced invasion capability.C. jejuni capCmutants caused reduced interleukin 8 (IL-8) secretion from intestinal epithelial cells and elicited a significantly diminished immune reaction inGallerialarvae, indicating that CapC functions as an immunogen. In conclusion, CapC is a new virulence determinant ofC. jejunithat contributes to the integral infection process of adhesion to human intestinal epithelial cells.IMPORTANCECampylobacter jejuniis a major causative agent of human gastroenteritis, making this zoonotic pathogen of significant importance to human and veterinary public health worldwide. The mechanisms by whichC. jejuniinteracts with intestinal epithelial cells and causes disease are still poorly understood due, in part, to the heterogeneity ofC. jejuniinfection biology. Given the importance ofC. jejunito public health, the need to characterize novel and existing virulence mechanisms is apparent. The significance of our research is in demonstrating the role of CapC, a novel virulence factor inC. jejunithat contributes to adhesion and invasion of the intestinal epithelium, thereby in part, addressing the dearth of knowledge concerning the factors involved inCampylobacterpathogenesis and the variation observed in the severity of human infection.

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