Role of the gp85/Trans-Sialidases in Trypanosoma cruzi Tissue Tropism: Preferential Binding of a Conserved Peptide Motif to the Vasculature in Vivo

Background: Transmitted by blood-sucking insects, the unicellular parasite Trypanosoma cruzi is the causative agent of Chagas' disease, a malady manifested in a variety of symptoms from heart disease to digestive and urinary tract dysfunctions. the reasons for such organ preference have been a matter of great interest in the field, particularly because the parasite can invade nearly every cell line and it can be found in most tissues following an infection. Among the molecular factors that contribute to virulence is a large multigene family of proteins known as gp85/trans-sialidase, which participates in cell attachment and invasion. But whether these proteins also contribute to tissue homing had not yet been investigated. Here, a combination of endothelial cell immortalization and phage display techniques has been used to investigate the role of gp85/trans-sialidase in binding to the vasculature.Methods: Bacteriophage expressing an important peptide motif (denominated FLY) common to all gp85/trans-sialidase proteins was used as a surrogate to investigate the interaction of this motif with the endothelium compartment. for that purpose phage particles were incubated with endothelial cells obtained from different organs or injected into mice intravenously and the number of phage particles bound to cells or tissues was determined. Binding of phages to intermediate filament proteins has also been studied.Findings and Conclusions: Our data indicate that FLY interacts with the endothelium in an organ-dependent manner with significantly higher avidity for the heart vasculature. Phage display results also show that FLY interaction with intermediate filament proteins is not limited to cytokeratin 18 (CK18), which may explain the wide variety of cells infected by the parasite. This is the first time that members of the intermediate filaments in general, constituted by a large group of ubiquitously expressed proteins, have been implicated in T. cruzi cell invasion and tissue homing.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilUniv São Paulo, Inst Quim, Dept Bioquim, BR-01498 São Paulo, BrazilUniv Texas MD Anderson Canc Ctr, David H Koch Ctr, Houston, TX 77030 USAUniv Texas MD Anderson Canc Ctr, Dept Canc Biol, Houston, TX 77030 USAUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilFAPESP: 2004/03303-5FAPESP: 2008/54.806-8Web of Scienc

Staphylococcal biofilm formation and development: Related diseases, host immune responses and therapy

Various biomolecular and regulatory factors are involved in adhesion, biofilm formation and host immune evasion of staphylococcal species. Adherence of staphylococcal species to either biotic or abiotic surfaces are a critical first event in the establishment of infection with these serious pathogens. A variety of proteinaceous and non-proteinaceous adhesins are known to mediate attachment to a multitude of host factors, such as extracellular matrix, and plasma proteins, and human host cells or inter-bacterial cell adhesins, which is essential for biofilm accumulation. Formation of the biofilm is a two-step process: (1) adherence of the pathogen to a surface and (2) further progression by accumulation of cells to form multilayered cell clusters. Biofilm is one of the important virulence factor of staphylococci that plays a role in many device-related infections such as native valve endocarditis, otitis media, urinary tract infections, cystic fibrosis, and acute septic arthritis, The increasing prevalence of antibiotic resistant strains and the vast ability of bacteria to evade host immune defenses are becoming more and more important for medical infections. The present review focuses on the role of specific cell surface adhesins, the ica operon, accumulation-associated proteins and quorum-sensing systems in the adhesion and infection processes of the Gram-positive pathogens, Staphylococcus epidermidis and Staphylococcus aureus. In addition, we will discuss staphylococcal biofilm-associated diseases and host immune responses, along with the current and future therapeutic strategies for staphylococcal biofilm infections including chemotherapeutic, vaccine and the nanotechnology application

The FLY phage mimics the VTVTNVFLYNRPLN peptide.

<p>(a) Binding of FLY phage and fd-tet to immobilized CK18 and to (b) LLC-MK₂ cells. (c) Binding of FLY phage to CK18 in the presence of increasing concentrations of VTVTNVFLYNRPLN synthetic peptide (FLY, black squares) or the alanine mutagenized version VTVTNVFAYNRPLN synthetic peptide (FAY, open triangles). Results are show as percentage of binding relative to FLY phage in the absence of peptides. Shown are standard error of the mean (SEM) of two biological replicates performed in triplicate.</p

FLY phage binding to organ-derived endothelial cells.

<p>Binding of FLY phage to bone marrow, bladder, heart or lung-derived endothelial cells; fd-tet and FAY phage were used as control. Phage binding was normalized to endothelial cell DNA, quantified using ribosomal RNA specific probes. The error bars are standard error of the mean (SEM) of experiments performed in triplicate. Where indicated, * denotes P<0.05.</p

FLY phage interaction with intermediate filament proteins.

<p>Phage binding to immobilized cytokeratin-8 (CK8), -18 (CK18) and -20 (CK20), and to vimentin. The FAY and fd-tet phage were used as control. Shown are SEM of experiments performed in triplicate. Where indicated, * denotes P<0.05.</p

First Measurement of the Total Inelastic Cross-Section of Positively-Charged Kaons on Argon at Energies Between 5.0 and 7.5 GeV

International audienceProtoDUNE Single-Phase (ProtoDUNE-SP) is a 770-ton liquid argon time projection chamber that operated in a hadron test beam at the CERN Neutrino Platform in 2018. We present a measurement of the total inelastic cross section of charged kaons on argon as a function of kaon energy using 6 and 7 GeV/$c$ beam momentum settings. The flux-weighted average of the extracted inelastic cross section at each beam momentum setting was measured to be 380$\pm$26 mbarns for the 6 GeV/$c$ setting and 379$\pm$35 mbarns for the 7 GeV/$c$ setting

First Measurement of the Total Inelastic Cross-Section of Positively-Charged Kaons on Argon at Energies Between 5.0 and 7.5 GeV

International audienceProtoDUNE Single-Phase (ProtoDUNE-SP) is a 770-ton liquid argon time projection chamber that operated in a hadron test beam at the CERN Neutrino Platform in 2018. We present a measurement of the total inelastic cross section of charged kaons on argon as a function of kaon energy using 6 and 7 GeV/$c$ beam momentum settings. The flux-weighted average of the extracted inelastic cross section at each beam momentum setting was measured to be 380$\pm$26 mbarns for the 6 GeV/$c$ setting and 379$\pm$35 mbarns for the 7 GeV/$c$ setting