Biomedical subjects

Jacek Bielecki

Publications and source records attributed to Jacek Bielecki.

5 recordsLinked to original sources

PubMed2006

Associated roles of hemolysin and p60 protein for the intracellular growth of Bacillus subtilis.

Hemolysin expressing Bacillus subtilis strain (B. subtilis ble/hlA) was used as a carrier for listerial protein p60 to study the impact of this protein on bacterial virulence independent of other gene products of Listeria monocytogenes. Bacillus subtilis ble/hlyA exhibited longer cell chains than B. subtilis ble/hlyA/iap. Recombinant Bacillus strains are able to adhere to the mouse macrophage-like J774 and human epithelial-like Int407 cell lines. The bacterial number of B. subtilis ble/hlyA/iap strain that adhered to the Int407 cell lines was 2.52-fold higher, and its invasion level strain was 2.66-fold higher than that observed for the hemolytic strain. Microscopy analysis of infected monolayers showed that recombinant B. subtilis cells were localized inside the cytoplasm of epithelial cells, near to the nuclei, in cellular compartments with low internal pH. Furthermore, in cells infected with bacteria, the actin structures rapidly changed and accumulation of a fat, wide actin layer around the nucleus zone was observed.

Actins↗

PubMed2005

Listeria monocytogenes listeriolysin O and phosphatidylinositol-specific phospholipase C affect adherence to epithelial cells.

Listeria monocytogenes, a foodborn intracellular animal and human pathogen, produces several exotoxins contributing to virulence. Among these are listeriolysin O (LLO), a pore-forming cholesterol-dependent hemolysin, and a phosphatidylinositol-specific phospholipase C (PI-PLC). LLO is known to play an important role in the escape of bacteria from the primary phagocytic vacuole of macrophages, and PI-PLC supports this process. Evidence is accumulating that LLO and PI-PLC are multifunctional virulence factors with many important roles in the host-parasite interaction other than phagosomal membrane disruption. LLO and PI-PLC may induce a number of host cell responses by modulating signal transduction of infected cells via intracellular Ca2+ levels and the metabolism of phospholipids. This would result in the activation of host phospholipase C and protein kinase C. In the present study, using Bacillus sub tilis strains expressing LLO, PI-PLC, and simultaneously LLO and PI-PLC, we show that LLO and PI-PLC enhance bacterial binding to epithelial cells Int407, with LLO being necessary and PI-PLC playing an accessory role. The results of this work suggest that these two listerial proteins act on epithelial cells prior to internalization.

Animals↗

PubMed2004

Molecular aspects of Listeria monocytogenes infection.

Listeria monocytogenes, a food-borne intracellular animal and human pathogen, interacts with infected host cells both prior to entry and during the intracellular phase of infection. This review is focused on the role of secreted proteins, including listeriolysin O and two distinct phospholipases C, in modulating the signal transduction of infected cells.

Bacterial Toxins↗

PubMed2004

Polymerizer-mediated intracellular movement.

Bacterial movement inside the cytoplasm is a major virulence factor in that it is necessary for efficient colonization of the infected tissues. Molecules from both the host and the pathogen present possible sites of pharmacologic intervention. Because locomoting Listeria and Shigella mimic the activated state of the leading edge of nonmuscle cells, these pathogens are powerful tools for dissecting the molecular machinery of actin-based motility. Analysis of the movement linked to cytoskeleton may lead to: (I) improved understanding of the mechanisms of disease transmission, including carriers and carrier states, pathogen movements, environmental factors and pharmacokinetics of the uptake and residues of vaccines and other biologics, and drugs in cultivated organisms; (II) new therapeutic developments, since it identifies the molecular targets involved in the pathogenicity of Listeria and Shigella and vaccinia intracellular enveloped virus. Recent knowledge about the intracellular movement in cytoplasm may lead to a better understanding of the processes governing actin dynamics within the cell and disease spread.

Actins↗

PubMed2003

Emerging food pathogens and bacterial toxins.

Many different foodborne diseases have been described. For example, Shigella bacteria, hepatitis A virus and Norwalk virus were shown as a unwashed hands microorganisms, but pathogen Campylobacter and Escherichia coli were named as raw and undercooked meat and poultry or raw milk and untreated water born bacteria. However, two of them: Listeria monocytogenes and Yersinia enterocolitica are known as growing at refrigerator temperatures. Essential virulence determinants of Listeria monocytogenes pathogenicity are well known as a bacterial toxins. Basic molecular mechanisms of pathogenicity depending from these toxins were presented. It was shown that other bacterial toxins may act as very danger food poisoning substances. This is why elimination of pathogenic microorganisms from foods is an obvious solution in some food processes, however this approach is not practical or even desirable in many processes. Thus, risk assessment and microbial monitoring will continue to play important roles in ensuring food safety. Some technological advances have the capability of delivering detection systems that can not only monitor pathogenic microorganisms, but also entire microbial populations in the food matrix.

Bacterial Toxins↗