scholarly journals Modulation of Early β-Defensin-2 Production as a Mechanism Developed by Type I Toxoplasma gondii To Evade Human Intestinal Immunity

2011 ◽  
Vol 79 (5) ◽  
pp. 2043-2050 ◽  
Author(s):  
Vijay Morampudi ◽  
Michel Y. Braun ◽  
Sushila D'Souza
Keyword(s):  
Gene Expression ◽  
Toxoplasma Gondii ◽  
Early Time ◽  
Host Cells ◽  
Poly I:C ◽  
Type I ◽  
Intestinal Epithelial ◽  
Intestinal Immunity ◽  
Content Type ◽  
Human Intestinal Epithelial Cells

ABSTRACTWe investigated the early innate immune responses induced in human intestinal epithelial cells (IEC) by the three definedToxoplasma gondiigenotype strains. Transcriptome analysis revealed that among differentially expressed genes, β-defensins distinguished the most IEC infected by fast- or slow-replicatingT. gondiigenotypes. Although β-defensin 1 and 3 genes were not expressed in host cells at early time points postinfection, the slow-replicating type II and III parasites induced high levels of β-defensin 2 gene expression. Notably, no β-defensin 2 gene expression occurred early after infection with the fast-replicating type I parasite. However, activation of this gene in IEC by poly(I:C) treatment prior to infection substantially decreased parasite viability, and pretreatment of parasites with synthetic β-defensin 2 significantly reduced their infectivity of IEC. These findings strongly support the modulation of early β-defensin 2 expression as a mechanism used by type IT. gondiiparasites to mediate immune evasion.

scholarly journals Transcriptome Analysis of Mouse Brain Infected with Toxoplasma gondii

2013 ◽  
Vol 81 (10) ◽  
pp. 3609-3619 ◽  
Author(s):  
Sachi Tanaka ◽  
Maki Nishimura ◽  
Fumiaki Ihara ◽  
Junya Yamagishi ◽  
Yutaka Suzuki ◽  
...  
Keyword(s):  
Gene Expression ◽  
Toxoplasma Gondii ◽  
Immune Responses ◽  
Mouse Brain ◽  
Transcriptome Analysis ◽  
Host Cells ◽  
Content Type ◽  
Host Immune Responses ◽  
Wide Range ◽  
The Brain

ABSTRACTToxoplasma gondiiis an obligate intracellular parasite that invades a wide range of vertebrate host cells. Chronic infections withT. gondiibecome established in the tissues of the central nervous system, where the parasites may directly or indirectly modulate neuronal function. However, the mechanisms underlying parasite-induced neuronal disorder in the brain remain unclear. This study evaluated host gene expression in mouse brain following infection withT. gondii. BALB/c mice were infected with the PLK strain, and after 32 days of infection, histopathological lesions in the frontal lobe were found to be more severe than in other areas of the brain. Total RNA extracted from infected and uninfected mouse brain samples was subjected to transcriptome analysis using RNA sequencing (RNA-seq). In theT. gondii-infected mice, 935 mouse brain genes were upregulated, whereas 12 genes were downregulated. GOstat analysis predicted that the upregulated genes were primarily involved in host immune responses and cell activation. Positive correlations were found between the numbers of parasites in the infected mouse brains and the expression levels of genes involved in host immune responses. In contrast, genes that had a negative correlation with parasite numbers were predicted to be involved in neurological functions, such as small-GTPase-mediated signal transduction and vesicle-mediated transport. Furthermore, differential gene expression was observed between mice exhibiting the clinical signs of toxoplasmosis and those that did not. Our findings may provide insights into the mechanisms underlying neurological changes duringT. gondiiinfection.

scholarly journals IscR Is a Global Regulator Essential for Pathogenesis of Vibrio vulnificus and Induced by Host Cells

2013 ◽  
Vol 82 (2) ◽  
pp. 569-578 ◽  
Author(s):  
Jong Gyu Lim ◽  
Sang Ho Choi
Keyword(s):  
Hemolytic Activity ◽  
Vibrio Vulnificus ◽  
Mutational Analysis ◽  
Host Cells ◽  
Intestinal Epithelial ◽  
Global Regulator ◽  
Content Type ◽  
Reading Frame ◽  
Human Intestinal Epithelial Cells ◽  
Whole Genome Microarray

ABSTRACTA mutant that exhibited less cytotoxic activity toward INT-407 human intestinal epithelial cells than the wild type was screened from a random transposon mutant library ofVibrio vulnificus, and an open reading frame encoding an Fe-S cluster regulator, IscR, was identified using a transposon-tagging method. A mutational analysis demonstrated that IscR contributes to mouse mortality as well as cytotoxicity toward the INT-407 cells, indicating that IscR is essential for the pathogenesis ofV. vulnificus. A whole-genome microarray analysis revealed that IscR influenced the expression of 67 genes, of which 52 were upregulated and 15 were downregulated. Among these, 12 genes most likely involved in motility and adhesion to host cells, hemolytic activity, and survival under oxidative stress of the pathogen during infection were selected and experimentally verified to be upregulated by IscR. Accordingly, the disruption ofiscRresulted in a significant reduction in motility and adhesion to INT-407 cells, in hemolytic activity, and in resistance to reactive oxygen species (ROS) such as H2O2andtert-butyl hydroperoxide (t-BOOH). Furthermore, the present study demonstrated thatiscRexpression was induced by exposure ofV. vulnificusto the INT-407 cells, and the induction appeared to be mediated by ROS generated by the host cells during infection. Consequently, the combined results indicated that IscR is a global regulator that contributes to the overall success in the pathogenesis ofV. vulnificusby regulating the expression of various virulence and survival genes in addition to Fe-S cluster genes.

scholarly journals Influence of Exposure Time on Gene Expression by Human Intestinal Epithelial Cells Exposed to Lactobacillus acidophilus

2012 ◽  
Vol 78 (14) ◽  
pp. 5028-5032 ◽  
Author(s):  
Sarah O'Flaherty ◽  
Todd R. Klaenhammer
Keyword(s):  
Gene Expression ◽  
Lactobacillus Acidophilus ◽  
Target Genes ◽  
Intestinal Epithelial Cells ◽  
Intestinal Cells ◽  
Intestinal Epithelial ◽  
Content Type ◽  
Temporal Gene Expression ◽  
Human Intestinal Epithelial Cells ◽  
Human Intestinal Cells

ABSTRACTAnalysis of global temporal gene expression by human intestinal cells when exposed toLactobacillus acidophilusrevealed induction of immune-related pathways and NF-κB target genes after a 1-h exposure, compared to a 4- or 8-h exposure. Additionally, anL. acidophilusderivative expressing covalently bound flagellin resulted in increased induction ofil8,cxc1, andcxcl2compared to the parentL. acidophilus.

scholarly journals Toxoplasma gondii Inhibits Gamma Interferon (IFN-γ)- and IFN-β-Induced Host Cell STAT1 Transcriptional Activity by Increasing the Association of STAT1 with DNA

2013 ◽  
Vol 82 (2) ◽  
pp. 706-719 ◽  
Author(s):  
Emily E. Rosowski ◽  
Quynh P. Nguyen ◽  
Ana Camejo ◽  
Eric Spooner ◽  
Jeroen P. J. Saeij
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Transcriptional Activation ◽  
Histone Deacetylases ◽  
Gamma Interferon ◽  
Host Cells ◽  
Secondary Response ◽  
Type I ◽  
Content Type ◽  
Ifn Γ

ABSTRACTThe gamma interferon (IFN-γ) response, mediated by the STAT1 transcription factor, is crucial for host defense against the intracellular pathogenToxoplasma gondii, but prior infection withToxoplasmacan inhibit this response. Recently, it was reported that theToxoplasmatype II NTE strain prevents the recruitment of chromatin remodeling complexes containing Brahma-related gene 1 (BRG-1) to promoters of IFN-γ-induced secondary response genes such asCiitaand major histocompatibility complex class II genes in murine macrophages, thereby inhibiting their expression. We report here that a type I strain ofToxoplasmainhibits the expression of primary IFN-γ response genes such asIRF1through a distinct mechanism not dependent on the activity of histone deacetylases. Instead, infection with a type I, II, or III strain ofToxoplasmainhibits the dissociation of STAT1 from DNA, preventing its recycling and further rounds of STAT1-mediated transcriptional activation. This leads to increased IFN-γ-induced binding of STAT1 at theIRF1promoter in host cells and increased global IFN-γ-induced association of STAT1 with chromatin.Toxoplasmatype I infection also inhibits IFN-β-induced interferon-stimulated gene factor 3-mediated gene expression, and this inhibition is also linked to increased association of STAT1 with chromatin. The secretion of proteins into the host cell by a type I strain ofToxoplasmawithout complete parasite invasion is not sufficient to block STAT1-mediated expression, suggesting that the effector protein responsible for this inhibition is not derived from the rhoptries.

scholarly journals AMA1-Deficient Toxoplasma gondii Parasites Transiently Colonize Mice and Trigger an Innate Immune Response That Leads to Long-Lasting Protective Immunity

2015 ◽  
Vol 83 (6) ◽  
pp. 2475-2486 ◽  
Author(s):  
Vanessa Lagal ◽  
Márcia Dinis ◽  
Dominique Cannella ◽  
Daniel Bargieri ◽  
Virginie Gonzalez ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Distinct Type ◽  
Genetically Engineered ◽  
Host Cells ◽  
Type I ◽  
Content Type ◽  
Apical Membrane Antigen 1 ◽  
Immunocompromised Mice

The apical membrane antigen 1 (AMA1) protein was believed to be essential for the perpetuation of two Apicomplexa parasite genera,PlasmodiumandToxoplasma, until we genetically engineered viable parasites lackingAMA1. The reduction in invasiveness of theToxoplasma gondiiRH-AMA1 knockout (RH-AMA1KO) tachyzoite population,in vitro, raised key questions about the outcome associated with these tachyzoites once inoculated in the peritoneal cavity of mice. In this study, we used AMNIS technology to simultaneously quantify and image the parasitic process driven by AMA1KOtachyzoites. We report their ability to colonize and multiply in mesothelial cells and in both resident and recruited leukocytes. While the RH-AMA1KOpopulation amplification is rapidly lethal in immunocompromised mice, it is controlled in immunocompetent hosts, where immune cells in combination sense parasites and secrete proinflammatory cytokines. This innate response further leads to a long-lasting status immunoprotective against a secondary challenge by high inocula of the homologous type I or a distinct type IIT. gondiigenotypes. While AMA1 is definitively not an essential protein for tachyzoite entry and multiplication in host cells, it clearly assists the expansion of parasite populationin vivo.

scholarly journals Garcinol Inhibits GCN5-Mediated Lysine Acetyltransferase Activity and Prevents Replication of the Parasite Toxoplasma gondii

2016 ◽  
Vol 60 (4) ◽  
pp. 2164-2170 ◽  
Author(s):  
Victoria Jeffers ◽  
Hongyu Gao ◽  
Lisa A. Checkley ◽  
Yunlong Liu ◽  
Michael T. Ferdig ◽  
...  
Keyword(s):  
Gene Expression ◽  
Toxoplasma Gondii ◽  
Gene Expression Regulation ◽  
Protozoan Parasite ◽  
Host Cells ◽  
Lysine Acetylation ◽  
Protein Activity ◽  
Content Type ◽  
Gene Expression Control ◽  
Aberrant Gene

ABSTRACTLysine acetylation is a critical posttranslational modification that influences protein activity, stability, and binding properties. The acetylation of histone proteins in particular is a well-characterized feature of gene expression regulation. In the protozoan parasiteToxoplasma gondii, a number of lysine acetyltransferases (KATs) contribute to gene expression and are essential for parasite viability. The natural product garcinol was recently reported to inhibit enzymatic activities of GCN5 and p300 family KATs in other species. Here we show that garcinol inhibits TgGCN5b, the only nuclear GCN5 family KAT known to be required forToxoplasmatachyzoite replication. Treatment of tachyzoites with garcinol led to a reduction of global lysine acetylation, particularly on histone H3 and TgGCN5b itself. We also performed transcriptome sequencing (RNA-seq), which revealed increasing aberrant gene expression coincident with increasing concentrations of garcinol. The majority of the genes that were most significantly affected by garcinol were also associated with TgGCN5b in a previously reported chromatin immunoprecipitation assay with microarray technology (ChIP-chip) analysis. The dysregulated gene expression induced by garcinol significantly inhibitsToxoplasmatachyzoite replication, and the concentrations used exhibit no overt toxicity on human host cells. Garcinol also inhibitsPlasmodium falciparumasexual replication with a 50% inhibitory concentration (IC50) similar to that forToxoplasma. Together, these data support that pharmacological inhibition of TgGCN5b leads to a catastrophic failure in gene expression control that prevents parasite replication.

scholarly journals Simultaneous Ribosome Profiling of Human Host Cells Infected with Toxoplasma gondii

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Michael J. Holmes ◽  
Premal Shah ◽  
Ronald C. Wek ◽  
William J. Sullivan
Keyword(s):  
Gene Expression ◽  
Toxoplasma Gondii ◽  
Host Cell ◽  
Ribosome Profiling ◽  
Host Gene ◽  
Host Cells ◽  
Host Gene Expression ◽  
Content Type ◽  
Quiescent Cells ◽  
Study Gene Expression

ABSTRACT Toxoplasma gondii is a ubiquitous obligate intracellular parasite that infects the nucleated cells of warm-blooded animals. From within the parasitophorous vacuole in which they reside, Toxoplasma tachyzoites secrete an arsenal of effector proteins that can reprogram host gene expression to facilitate parasite survival and replication. Gaining a better understanding of how host gene expression is altered upon infection is central for understanding parasite strategies for host invasion and for developing new parasite therapies. Here, we applied ribosome profiling coupled with mRNA measurements to concurrently study gene expression in the parasite and in host human foreskin fibroblasts. By examining the parasite transcriptome and translatome, we identified potential upstream open reading frames that may permit the stress-induced preferential translation of parasite mRNAs. We also determined that tachyzoites reduce host death-associated pathways and increase survival, proliferation, and motility in both quiescent and proliferative host cell models of infection. Additionally, proliferative cells alter their gene expression in ways that are consistent with massive transcriptional rewiring, while quiescent cells were best characterized by reentry into the cell cycle. We also identified a translational control regimen consistent with mechanistic target of rapamycin (mTOR) activation in quiescent cells and, to a lesser degree, in proliferative cells. This study illustrates the utility of the method for dissection of gene expression programs simultaneously in the parasite and host. IMPORTANCE Toxoplasma gondii is a single-celled parasite that has infected up to one-third of the world’s population. Significant overhauls in gene expression in both the parasite and the host cell accompany parasite invasion, and a better understanding of these changes may lead to the development of new therapeutic agents. In this study, we employed ribosome profiling to determine the changes that occur at the levels of transcription and translation in both the parasite and the infected host cell at the same time. We discovered features of Toxoplasma mRNAs that suggest a means for controlling parasite gene expression under stressful conditions. We also show that differences in host gene expression occur depending on whether they are confluent or not. Our findings demonstrate the feasibility of using ribosomal profiling to interrogate the host-parasite dynamic under a variety of conditions.

scholarly journals Modulation of Chicken Intestinal Immune Gene Expression by Small Cationic Peptides as Feed Additives during the First Week Posthatch

2013 ◽  
Vol 20 (9) ◽  
pp. 1440-1448 ◽  
Author(s):  
Michael H. Kogut ◽  
Kenneth J. Genovese ◽  
Haiqi He ◽  
Christina L. Swaggerty ◽  
Yiwei Jiang
Keyword(s):  
Gene Expression ◽  
Proinflammatory Cytokines ◽  
Proinflammatory Cytokine ◽  
Feed Additives ◽  
Feed Additive ◽  
Cationic Peptides ◽  
Type I ◽  
Immune Gene ◽  
Content Type ◽  
Functional Efficiency

ABSTRACTWe have been investigating modulation strategies tailored around the selective stimulation of the host's immune system as an alternative to direct targeting of microbial pathogens by antibiotics. One such approach is the use of a group of small cationic peptides (BT) produced by a Gram-positive soil bacterium,Brevibacillus texasporus. These peptides have immune modulatory properties that enhance both leukocyte functional efficiency and leukocyte proinflammatory cytokine and chemokine mRNA transcription activitiesin vitro. In addition, when provided as a feed additive for just 4 days posthatch, BT peptides significantly induce a concentration-dependent protection against cecal and extraintestinal colonization bySalmonella entericaserovar Enteritidis. In the present studies, we assessed the effects of feeding BT peptides on transcriptional changes on proinflammatory cytokines, inflammatory chemokines, and Toll-like receptors (TLR) in the ceca of broiler chickens with and withoutS. Enteritidis infection. After feeding a BT peptide-supplemented diet for the first 4 days posthatch, chickens were then challenged withS. Enteritidis, and intestinal gene expression was measured at 1 or 7 days postinfection (p.i.) (5 or 11 days of age). Intestinal expression of innate immune mRNA transcripts was analyzed by quantitative real-time PCR (qRT-PCR). Analysis of relative mRNA expression showed that a BT peptide-supplemented diet did not directly induce the transcription of proinflammatory cytokine, inflammatory chemokine, type I/II interferon (IFN), or TLR mRNA in chicken cecum. However, feeding the BT peptide-supplemented diet primed cecal tissue for increased (P≤ 0.05) transcription of TLR4, TLR15, and TLR21 upon infection withS. Enteritidis on days 1 and 7 p.i. Likewise, feeding the BT peptides primed the cecal tissue for increased transcription of proinflammatory cytokines (interleukin 1β [IL-1β], IL-6, IL-18, type I and II IFNs) and inflammatory chemokine (CxCLi2) in response toS. Enteritidis infection 1 and 7 days p.i. compared to the chickens fed the basal diet. These small cationic peptides may prove useful as alternatives to antibiotics as local immune modulators in neonatal poultry by providing prophylactic protection againstSalmonellainfections.

scholarly journals Expression, Purification, and Biological Characterization of Babesia microti Apical Membrane Antigen 1

2015 ◽  
Vol 83 (10) ◽  
pp. 3890-3901 ◽  
Author(s):  
Prasun Moitra ◽  
Hong Zheng ◽  
Vivek Anantharaman ◽  
Rajdeep Banerjee ◽  
Kazuyo Takeda ◽  
...  
Keyword(s):  
Apical Membrane ◽  
The United States ◽  
Host Cells ◽  
Health Concern ◽  
Babesia Microti ◽  
Type I ◽  
Content Type ◽  
Apical Membrane Antigen 1 ◽  
Apical Membrane Antigen ◽  
Extracellular Region

The intraerythrocytic apicomplexanBabesia microti, the primary causative agent of human babesiosis, is a major public health concern in the United States and elsewhere. Apicomplexans utilize a multiprotein complex that includes a type I membrane protein called apical membrane antigen 1 (AMA1) to invade host cells. We have isolated the full-lengthB. microtiAMA1 (BmAMA1) gene and determined its nucleotide sequence, as well as the amino acid sequence of the AMA1 protein. This protein contains an N-terminal signal sequence, an extracellular region, a transmembrane region, and a short conserved cytoplasmic tail. It shows the same domain organization as the AMA1 orthologs from piroplasm, coccidian, and haemosporidian apicomplexans but differs from all other currently known piroplasmida, including otherBabesiaandTheileriaspecies, in lacking two conserved cysteines in highly variable domain III of the extracellular region. Minimal polymorphism was detected in BmAMA1 gene sequences of parasite isolates from six babesiosis patients from Nantucket. Immunofluorescence microscopy studies showed that BmAMA1 is localized on the cell surface and cytoplasm near the apical end of the parasite. Native BmAMA1 from parasite lysate and refolded recombinant BmAMA1 (rBmAMA1) expressed inEscherichia colireacted with a mouse anti-BmAMA1 antibody using Western blotting.In vitrobinding studies showed that both native BmAMA1 and rBmAMA1 bind to human red blood cells (RBCs). This binding is trypsin and chymotrypsin treatment sensitive but neuraminidase independent. Incubation ofB. microtiparasites in human RBCs with a mouse anti-BmAMA1 antibody inhibited parasite growth by 80% in a 24-h assay. Based on its antigenically conserved nature and potential role in RBC invasion, BmAMA1 should be evaluated as a vaccine candidate.

scholarly journals Naturally Occurring Motility-Defective Mutants of Salmonella enterica Serovar Enteritidis Isolated Preferentially from Nonhuman Rather than Human Sources

2011 ◽  
Vol 77 (21) ◽  
pp. 7740-7748 ◽  
Author(s):  
Lucía Yim ◽  
Laura Betancor ◽  
Arací Martínez ◽  
Clare Bryant ◽  
Duncan Maskell ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Intestinal Epithelial ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Transcriptional Responses ◽  
Content Type ◽  
Field Isolates ◽  
Specific Pcr ◽  
Human Intestinal Epithelial Cells ◽  
Natural Isolates ◽  
Cell Invasiveness

ABSTRACTSalmonellosis represents a worldwide health problem because it is one of the major causes of food-borne disease. Although motility is postulated as an importantSalmonellavirulence attribute, there is little information about variation in motility in natural isolates. Here we report the identification of a point mutation (T551 → G) inmotA, a gene essential for flagellar rotation, in severalSalmonella entericaserovar Enteritidis field isolates. This mutation results in bacteria that can biosynthesize structurally normal but paralyzed flagella and are impaired in their capacity to invade human intestinal epithelial cells. Introduction of a wild-type copy ofmotAinto one of these isolates restored both motility and cell invasiveness. ThemotAmutant triggered higher proinflammatory transcriptional responses than an aflagellate isolate in differentiated Caco-2 cells, suggesting that the paralyzed flagella are able to signal through pattern recognition receptors. A specific PCR was designed to screen for the T551 → G mutation in a collection of 266S. Enteritidis field isolates from a nationwide epidemic, comprising 194 from humans and 72 from other sources. We found that 72 of the 266 (27%) isolates were nonmotile, including 24.7% (48/194) of human and 33.3% (24/72) of food isolates. Among nonmotile isolates, 15 carried the T551 → G mutation and, significantly, 13 were recovered from food, including 7 from eggs, but only 2 were from human sources. These results suggest that the presence of paralyzed flagella may impair the ability ofS. Enteritidis to cause disease in the human host but does not prevent its ability to colonize chickens and infect eggs.

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