Contribution of Hemagglutinin/Protease and Motility to the Pathogenesis of El Tor Biotype Cholera

ABSTRACT Vibrio cholerae is a highly motile organism that secretes a Zn-dependent metalloprotease, hemagglutinin/protease (HapA). HapA has been shown to have mucinase activity and contribute to the reactogenicity of live vaccine candidates, but its role in cholera pathogenesis is not yet clear. The contribution of motility to pathogenesis is not fully understood, since conflicting results have been obtained with different strains, mutants, and animal models. The objective of this work was to determine the contribution of HapA and motility to the pathogenesis of El Tor biotype cholera. To this end we constructed isogenic motility (motY) and mucinase (hapA) single and double mutants of an El Tor biotype V. cholerae strain. Mutants were characterized for the expression of major virulence factors in vitro and in vivo. The motility mutant showed a remarkable increase in cholera toxin (CT), toxin coregulated pilus major subunit (TcpA), and HapA production in vitro. Increased TcpA and CT production could be explained by increased transcription of tcpA, ctxA, and toxT. No effect was detected on the transcription of hapA in the motility mutant. The sodium ionophore monensin diminished production of HapA in the parent but not in the motility mutant. Phenamil, a specific inhibitor of the flagellar motor, diminished CT production in the wild-type and motY strains. The hapA mutant showed increased binding to mucin. In contrast, the motY mutation diminished adherence to biotic and abiotic surfaces including mucin. Lack of HapA did not affect colonization in the suckling mouse model. The motility and mucinase defects did not prevent induction of ctxA and tcpA in the mouse intestine as measured by recombinase-based in vivo expression technology. Analysis of mutants in the rabbit ileal loop model showed that both V. cholerae motility and HapA were necessary for full expression of enterotoxicity.

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Evaluation of in vivo and in vitro Biological Activity of a Vibrio Cholerae 01 Hemolysin

Clinical & Investigative Medicine ◽

10.25011/cim.v30i6.2953 ◽

2007 ◽

Vol 30 (6) ◽

pp. 250 ◽

Cited By ~ 1

Author(s):

Jose Arellano Galindo ◽

Maria Guadalupe Rodriquez Angeles ◽

Norma Valazquez Guadarrama ◽

Enrique Santos Esteban ◽

Silvia Giono Cerezo

Keyword(s):

Vibrio Cholerae ◽

Cell Cultures ◽

Polyclonal Antibody ◽

Elisa Test ◽

Bacterial Lipopolysaccharide ◽

Loop Model ◽

Intestinal Epithelial ◽

Ileal Loop

Purpose: To evaluate the hemolysin effect by ileal loop model produced by Vibrio cholerae O1 strains, compared with the cellular lysis or cytotoxic activity (CA) observed in cell culture. Method: We studied nine V. cholerae O1 strains, obtained during the Mexican outbreak of cholera (1990-1993), which had CA in Vero and CHO cells. Hemolysin was monitored with the hemolysis test. Titers of CA were calculated by CD50, and the association between CA and cholera toxin (CT) production was discarded by means of neutralization tests using an anti-CT polyclonal antibody. The CT production was measured with ELISA test. The LAL assay was performed in order to study relationships between the CA and bacterial lipopolysaccharide. Strains with CA were evaluated in rabbit and rat ileal loop models; hemorrhagic fluid was also measured. Tissues from ileal loop were included in paraffin to detect intestinal epithelial damage. Results: The hemolysin CA was not neutralized with the anti-CT polyclonal antibody. However, the associated factor of CA was heat labile. CA in cell cultures was not related to the bacterial lipopolysaccharide. The ileal loop test exhibited the presence of hemorrhagic tissue with inflammation. Conclusion: The V. cholerae O1 strains isolated were able to secrete hemolysin which, in turn, caused CA in cell cultures and produced the hemorrhagic and inflammatory effects observed in the ileal loop of rabbit and rat models.

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Norepinephrine Augments Salmonella enterica-Induced Enteritis in a Manner Associated with Increased Net Replication but Independent of the Putative Adrenergic Sensor Kinases QseC and QseE

Infection and Immunity ◽

10.1128/iai.01203-09 ◽

2009 ◽

Vol 78 (1) ◽

pp. 372-380 ◽

Cited By ~ 48

Author(s):

Gillian D. Pullinger ◽

Sonya C. Carnell ◽

Fathima F. Sharaff ◽

Pauline M. van Diemen ◽

Francis Dziva ◽

...

Keyword(s):

Salmonella Enterica ◽

Loop Model ◽

Intestinal Colonization ◽

Microbial Infection ◽

Ileal Loop ◽

Sensor Kinases ◽

Sense And Respond ◽

Bacterial Replication

ABSTRACT Stress has long been correlated with susceptibility to microbial infection. One explanation for this phenomenon is the ability of pathogens to sense and respond to host stress-related catecholamines, such as norepinephrine (NE). In Gram-negative enteric pathogens, it has been proposed that NE may facilitate growth by mediating iron supply, or it may alter gene expression by activating adrenergic sensor kinases. The aim of this work was to investigate the relative importance of these processes in a model in which NE alters the outcome of Salmonella enterica serovar Typhimurium infection. A bovine ligated ileal loop model was used to study the effect of NE on enteritis induced by S. Typhimurium and on the bacterial in vivo replication rate. Mutants lacking putative adrenergic receptor genes were assessed in the loop model, in a calf intestinal colonization model, and in vitro. S. Typhimurium-induced enteritis was significantly enhanced by addition of 5 mM NE. This effect was associated with increased net bacterial replication in the same model. Exogenous ferric iron also stimulated bacterial replication in the medium used but not transcription of enteritis-associated loci. The putative adrenergic sensors QseC and QseE were not required for NE-enhanced enteritis, intestinal colonization of calves, or NE-dependent growth in iron-restricted medium and did not influence expression or secretion of enteritis-associated virulence factors. Our findings support a role for stress-related catecholamines in modulating the virulence of enteric bacterial pathogens in vivo but suggest that bacterial adrenergic sensors may not be the vital link in such interkingdom signaling in Salmonella.

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Role of Intimin-Tir Interactions and the Tir-Cytoskeleton Coupling Protein in the Colonization of Calves and Lambs by Escherichia coli O157:H7

Infection and Immunity ◽

10.1128/iai.74.1.758-764.2006 ◽

2006 ◽

Vol 74 (1) ◽

pp. 758-764 ◽

Cited By ~ 48

Author(s):

Isabella Vlisidou ◽

Francis Dziva ◽

Roberto M. La Ragione ◽

Angus Best ◽

Junkal Garmendia ◽

...

Keyword(s):

Escherichia Coli ◽

Loop Model ◽

Intestinal Colonization ◽

Actin Assembly ◽

Ileal Loop ◽

E Coli ◽

Coupling Protein

ABSTRACT Intimin facilitates intestinal colonization by enterohemorrhagic Escherichia coli O157:H7; however, the importance of intimin binding to its translocated receptor (Tir) as opposed to cellular coreceptors is unknown. The intimin-Tir interaction is needed for optimal actin assembly under adherent bacteria in vitro, a process which requires the Tir-cytoskeleton coupling protein (TccP/EspFU) in E. coli O157:H7. Here we report that E. coli O157:H7 tir mutants are at least as attenuated as isogenic eae mutants in calves and lambs, implying that the role of intimin in the colonization of reservoir hosts can be explained largely by its binding to Tir. Mutation of tccP uncoupled actin assembly from the intimin-Tir-mediated adherence of E. coli O157:H7 in vitro but did not impair intestinal colonization in calves and lambs, implying that pedestal formation may not be necessary for persistence. However, an E. coli O157:H7 tccP mutant induced typical attaching and effacing lesions in a bovine ligated ileal loop model of infection, suggesting that TccP-independent mechanisms of actin assembly may operate in vivo.

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Local bacteriophage isolates showed anti-Escherichia coliO157:H7 potency in an experimental ligated rabbit ileal loop model

Canadian Journal of Microbiology ◽

10.1139/w11-020 ◽

2011 ◽

Vol 57 (5) ◽

pp. 408-415 ◽

Cited By ~ 3

Author(s):

Muntasir Alam ◽

Marufa Zerin Akhter ◽

Mahmuda Yasmin ◽

Chowdhury Rafiqul Ahsan ◽

Jamalun Nessa

Keyword(s):

Bacterial Growth ◽

Lytic Phage ◽

Loop Model ◽

Ileal Loop ◽

E Coli ◽

Combined Application ◽

Food Borne ◽

In Vivo Testing

Escherichia coli O157:H7 is considered among the most important recently emerged food-borne bacteria causing severe hemorrhagic diarrhea. Antibiotic treatment is not recommended as a prospective curative agent against this pathogen. Therefore, potency assessment of the local lytic phage isolates infecting E. coli O157:H7 as an alternate remedy to antibiotics was the principal concern of this study. Phage isolates against E. coli O157:H7 were checked by polymerase chain reaction for the presence of the virulence genes stx1 and stx2, and the safe phages were further screened in vitro for their capacity as biocontrol agents. Two bacteriophage strains, namely PAH6 and P2BH2, that had expressed potential antibacterial activity (P < 0.05) in vitro were selected for in vivo testing in ligated rabbit ileal loop models. Both phage isolates were capable of decreasing fluid accumulation in rabbit ileal loops along with reducing bacterial growth (r = 0.992). Combined application of the phages was found most satisfactory, reducing seven log cycles of bacterial growth. Consistent results in both in vivo and in vitro experiments demonstrate the applicability of bacteriophages as a rapid response tool against E. coli O157:H7. To our knowledge, this is the first successful application of the rabbit ileal loop test for therapeutic evaluation of bacteriophages.

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Activation of transmembrane receptor tyrosine kinase DDR1-STAT3 cascade by extracellular matrix remodeling promotes liver metastatic colonization in uveal melanoma

Signal Transduction and Targeted Therapy ◽

10.1038/s41392-021-00563-x ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Wei Dai ◽

Shenglan Liu ◽

Shubo Wang ◽

Li Zhao ◽

Xiao Yang ◽

...

Keyword(s):

Extracellular Matrix ◽

Cancer Cells ◽

Uveal Melanoma ◽

Specific Inhibitor ◽

Type I ◽

Matrix Remodeling ◽

Metastatic Colonization ◽

Tgf Β1

AbstractColonization is believed a rate-limiting step of metastasis cascade. However, its underlying mechanism is not well understood. Uveal melanoma (UM), which is featured with single organ liver metastasis, may provide a simplified model for realizing the complicated colonization process. Because DDR1 was identified to be overexpressed in UM cell lines and specimens, and abundant pathological deposition of extracellular matrix collagen, a type of DDR1 ligand, was noted in the microenvironment of liver in metastatic patients with UM, we postulated the hypothesis that DDR1 and its ligand might ignite the interaction between UM cells and their surrounding niche of liver thereby conferring strengthened survival, proliferation, stemness and eventually promoting metastatic colonization in liver. We tested this hypothesis and found that DDR1 promoted these malignant cellular phenotypes and facilitated metastatic colonization of UM in liver. Mechanistically, UM cells secreted TGF-β1 which induced quiescent hepatic stellate cells (qHSCs) into activated HSCs (aHSCs) which secreted collagen type I. Such a remodeling of extracellular matrix, in turn, activated DDR1, strengthening survival through upregulating STAT3-dependent Mcl-1 expression, enhancing stemness via upregulating STAT3-dependent SOX2, and promoting clonogenicity in cancer cells. Targeting DDR1 by using 7rh, a specific inhibitor, repressed proliferation and survival in vitro and in vivo outgrowth. More importantly, targeting cancer cells by pharmacological inactivation of DDR1 or targeting microenvironmental TGF-β1-collagen I loop exhibited a prominent anti-metastasis effect in mice. In conclusion, targeting DDR1 signaling and TGF-β signaling may be a novel approach to diminish hepatic metastasis in UM.

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The Capsule Encoding the viaB Locus Reduces Interleukin-17 Expression and Mucosal Innate Responses in the Bovine Intestinal Mucosa during Infection with Salmonella enterica Serotype Typhi

Infection and Immunity ◽

10.1128/iai.01571-06 ◽

2007 ◽

Vol 75 (9) ◽

pp. 4342-4350 ◽

Cited By ~ 69

Author(s):

Manuela Raffatellu ◽

Renato L. Santos ◽

Daniela Chessa ◽

R. Paul Wilson ◽

Sebastian E. Winter ◽

...

Keyword(s):

Mouse Model ◽

Salmonella Enterica ◽

Intestinal Inflammation ◽

Fluid Secretion ◽

Interleukin 17 ◽

Loop Model ◽

Wild Type ◽

Ileal Loop ◽

Chemokine Production

ABSTRACT The viaB locus contains genes for the biosynthesis and export of the Vi capsular antigen of Salmonella enterica serotype Typhi. Wild-type serotype Typhi induces less CXC chemokine production in tissue culture models than does an isogenic viaB mutant. Here we investigated the in vivo relevance of these observations by determining whether the presence of the viaB region prevents inflammation in two animal models of gastroenteritis. Unlike S. enterica serotype Typhimurium, serotype Typhi or a serotype Typhi viaB mutant did not elicit marked inflammatory changes in the streptomycin-pretreated mouse model. In contrast, infection of bovine ligated ileal loops with a serotype Typhi viaB mutant resulted in more fluid accumulation and higher expression of the chemokine growth-related oncogene alpha (GROα) and interleukin-17 (IL-17) than did infection with the serotype Typhi wild type. There was a marked upregulation of IL-17 expression in both the bovine ligated ileal loop model and the streptomycin-pretreated mouse model, suggesting that this cytokine is an important component of the inflammatory response to infection with Salmonella serotypes. Introduction of the cloned viaB region into serotype Typhimurium resulted in a significant reduction of GROα and IL-17 expression and in reduced fluid secretion. Our data support the idea that the viaB region plays a role in reducing intestinal inflammation in vivo.

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An optimised GAS-pharyngeal cell biofilm model

Scientific Reports ◽

10.1038/s41598-021-87377-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Heema K. N. Vyas ◽

Jason D. McArthur ◽

Martina L. Sanderson-Smith

Keyword(s):

Crystal Violet ◽

Biofilm Formation ◽

Cell Model ◽

Matrix Material ◽

Three Dimensional ◽

Growth Period ◽

Optimal Growth ◽

Abiotic Surfaces

AbstractGroup A Streptococcus (GAS) causes 700 million infections and accounts for half a million deaths per year. Biofilm formation has been implicated in both pharyngeal and dermal GAS infections. In vitro, plate-based assays have shown that several GAS M-types form biofilms, and multiple GAS virulence factors have been linked to biofilm formation. Although the contributions of these plate-based studies have been valuable, most have failed to mimic the host environment, with many studies utilising abiotic surfaces. GAS is a human specific pathogen, and colonisation and subsequent biofilm formation is likely facilitated by distinct interactions with host tissue surfaces. As such, a host cell-GAS model has been optimised to support and grow GAS biofilms of a variety of GAS M-types. Improvements and adjustments to the crystal violet biofilm biomass assay have also been tailored to reproducibly detect delicate GAS biofilms. We propose 72 h as an optimal growth period for yielding detectable biofilm biomass. GAS biofilms formed are robust and durable, and can be reproducibly assessed via staining/washing intensive assays such as crystal violet with the aid of methanol fixation prior to staining. Lastly, SEM imaging of GAS biofilms formed by this model revealed GAS cocci chains arranged into three-dimensional aggregated structures with EPS matrix material. Taken together, we outline an efficacious GAS biofilm pharyngeal cell model that can support long-term GAS biofilm formation, with biofilms formed closely resembling those seen in vivo.

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The Fungal Cyp51-Specific Inhibitor VT-1598 DemonstratesIn VitroandIn VivoActivity againstCandida auris

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02233-18 ◽

2018 ◽

Vol 63 (3) ◽

Cited By ~ 10

Author(s):

Nathan P. Wiederhold ◽

Shawn R. Lockhart ◽

Laura K. Najvar ◽

Elizabeth L. Berkow ◽

Rosie Jaramillo ◽

...

Keyword(s):

Specific Inhibitor ◽

Candida Auris ◽

Once Daily ◽

Content Type ◽

Fungal Burden ◽

Invasive Infections ◽

Trough Concentrations ◽

Dose Dependent

ABSTRACTCandida aurisis an emerging pathogen associated with significant mortality and often multidrug resistance. VT-1598, a tetrazole-based fungal CYP51-specific inhibitor, was evaluatedin vitroandin vivoagainstC. auris. Susceptibility testing was performed against 100 clinical isolates ofC. aurisby broth microdilution. Neutropenic mice were infected intravenously withC. auris, and treatment began 24 h postinoculation with a vehicle control, oral VT-1598 (5, 15, and 50 mg/kg of body weight once daily), oral fluconazole (20 mg/kg once daily), or intraperitoneal caspofungin (10 mg/kg once daily), which continued for 7 days. Fungal burden was assessed in the kidneys and brains on day 8 in the fungal burden arm and on the days the mice succumbed to infection or on day 21 in the survival arm. VT-1598 plasma trough concentrations were also assessed on day 8. VT-1598 demonstratedin vitroactivity againstC. auris, with a mode MIC of 0.25 μg/ml and MICs ranging from 0.03 to 8 μg/ml. Treatment with VT-1598 resulted in significant and dose-dependent improvements in survival (median survival, 15 and >21 days for VT-1598 at 15 and 50 mg/kg, respectively) and reductions in kidney and brain fungal burden (reductions of 1.88 to 3.61 log10CFU/g) compared to the control (5 days). The reductions in fungal burden correlated with plasma trough concentrations. Treatment with caspofungin, but not fluconazole, also resulted in significant improvements in survival and reductions in fungal burden compared to those with the control. These results suggest that VT-1598 may be a future option for the treatment of invasive infections caused byC. auris.

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Rationally Designing Simple Rod-Like Amphiphilic NIR-Emissive AIE Probes for Precise In-Vivo Detection of Aβ Fibrils/Plaques at A Super-Early Stage

10.26434/chemrxiv.13699222.v1 ◽

2021 ◽

Author(s):

Yipu Wang ◽

Dong Mei ◽

Xinyi Zhang ◽

Da-Hui Qu ◽

Ju Mei ◽

...

Keyword(s):

High Performance ◽

Ex Vivo ◽

Early Stage ◽

Signal To Noise Ratio ◽

High Signal ◽

In Vivo Detection ◽

Different Strains ◽

Aβ Fibrils

With increase of social aging, Alzheimer's disease (AD) has been one of the serious diseases threatening human health. The occurrence of Aβ fibrils or plaques is recognized as the hallmark of AD. Currently, optical imaging has stood out to be a promising technique for the imaging of Aβ fibrils/plaques and the diagnosis of AD. However, restricted by their poor blood-brain barrier (BBB) penetrability, short-wavelength excitation and emission, and aggregation-caused quenching (ACQ) effect, the clinically used gold-standard optical probes such as <a>thioflavin</a> T (ThT) and thioflavin S (ThS), are not effective enough in the early diagnosis of AD in vivo. Herein, we put forward an “all-in-one” design principle and demonstrate its feasibility in developing high-performance fluorescent probes which are specific to Aβ fibrils/plaques and promising for super-early in-vivo diagnosis of AD. As a proof of concept, a simple rod-like amphiphilic NIR fluorescent AIEgen, i.e., AIE-CNPy-AD, is developed by taking the specificity, BBB penetration ability, deep-tissue penetration capacity, high signal-to-noise ratio (SNR) into consideration. AIE-CNPy-AD is constituted by connecting the electron-donating and accepting moieties through single bonds and tagging with a propanesulfonate tail, giving rise to the NIR fluorescence, aggregation-induced emission (AIE) effect, amphiphilicity, and rod-like structure, which in turn result in high binding-affinity and excellent specificity to Aβ fibrils/plaques, satisfactory ability to penetrate BBB and deep tissues, ultrahigh SNR and sensitivity, and high-fidelity imaging capability. In-vitro, ex-vivo, and in-vivo <a>identifying of Aβ fibrils/plaques</a> in different strains of mice indicate that AIE-CNPy-AD holds the universality to the detection of Aβ fibrils/plaques. It is noteworthy that AIE-CNPy-AD is even able to trace the small and sparsely distributed Aβ fibrils/plaques in very young AD model mice such as 4-month-old APP/PS1 mice which are reported to be the youngest mice to have Aβ deposits in brains, suggesting its great potential in diagnosis and intervention of AD at a super-early stage.

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Translational evidence for RRM2 as a prognostic biomarker and therapeutic target in Ewing sarcoma

10.1101/2021.03.04.433896 ◽

2021 ◽

Author(s):

Shunya Ohmura ◽

Aruna Marchetto ◽

Martin F. Orth ◽

Jing Li ◽

Susanne Jabar ◽

...

Keyword(s):

Overall Survival ◽

Ewing Sarcoma ◽

Survival Data ◽

Therapeutic Target ◽

Prognostic Biomarker ◽

Specific Inhibitor ◽

Cell Cycle Checkpoint ◽

Regulatory Subunit

Purpose: Ewing sarcoma (EwS) is a highly aggressive bone- or soft tissue-associated malignancy mostly affecting children, adolescents, and young adults. Although multimodal therapies have strongly improved patients′ overall survival over the past decades, the development of prognostic biomarkers for risk-based patient stratification and more effective therapies with less adverse effects is stagnating. Thus, new personalized medicine approaches are urgently required. Experimental design: Gene expression data of EwS and normal tissues were crossed with survival data to identify highly overexpressed, prognostically relevant, and actionable potential targets. RNA-interference and dose-response assays as well as tissue-microarray analyses were carried out to explore the functional role and druggability of a prominent candidate gene in vitro and in vivo, and to validate its suitability as a prognostic biomarker. Results: Employing a multilayered screening approach, we discover ribonucleotide reductase regulatory subunit M2 (RRM2) as a promising therapeutic target and prognostic biomarker in EwS. Through analysis of two independent EwS patient cohorts, we show that RRM2 mRNA and protein overexpression is associated with an aggressive clinical phenotype and poor patients′ overall survival. In agreement, RRM2 silencing as well as pharmacological inhibition by the specific inhibitor triapine (3-AP) significantly reduces EwS growth in vitro and in vivo. Furthermore, we present evidence that pharmacological RRM2 inhibition by triapine can overcome chemoresistance against doxorubicin or gemcitabine, and synergize with cell cycle checkpoint inhibitors (CHEK1 or WEE1). Conclusions: Based on the aggressive phenotype mediated by and the druggability of RRM2 our results provide a translational rationale for exploiting RRM2 as a novel therapeutic target in EwS and prompt further clinical investigations.

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