Project description:Listeria monocytogenes is the ubiquitous food-borne pathogen which causes listeriosis, a disease with a high mortality rate, mostly transmitted through contaminated ready-to-eat foods (EFSA, 2018). To better understand the systemic response of such microorganism exposed at three environmental factors (T, pH and NaCl), the proteome of a L. monocytogenes strain, which was isolated from a meat product (Coppa di testa) linked to a listeriosis outbreak occurred in Marche region (Italy) in 2016, was investigated in order to identify differences in its protein patterns.
Project description:Listeria monocytogenes is a food-borne pathogen and the causative agent of listeriosis, an infection which typically arises through the consumption of contaminated foodstuffs. L. monocytogenes is a psychotrophic and facultatively anaerobic; properties which permit growth under refrigeration conditions and within modified atmosphere packaging. Through transcriptional changes L. monocytogenes is able to mount adaptive responses against stressors. Such responses typically cross protect against subsequent stresses.
Project description:Expression profiling by microarray was used with a murine listeriosis model to better understand increased susceptibility of preterm neonates to infection. We used DNA microarray to identify genes that were differentially expressed in liver of adult and neonatal Balb/c mice after listeriosis infection.
Project description:Listeria monocytogenes is a food-borne pathogen which causes listeriosis. It is an intracellular parasite invading the epithelial cells where it escapes from the vacuole into the host cytoplasm to replicate, using actin-based motility to move within and between cells. The intracellular life cycle is well documented whereas the time spent in the lumen of the intestine is poorly understood. The aim of this study was to investigate the mechanism by which L. monocytogenes adapts to the environment of the small intestine prior to invasion. Specifically, to determine if the PrfA regulon, that encodes the virulence factors of L. monocytogenes, is switched on by signals within the intestinal lumen. L. monocytogenes were grown under aerobic or microaerobic conditions with glucose or glycerol as carbon source.
Project description:Listeria monocytogenes is a foodborne intracellular bacterial pathogen leading to human listeriosis. Despite a high mortality rate and increasing antibiotic resistance no clinically approved vaccine against Listeria is available. To identify antigens for this bacterial pathogen that can be encoded in mRNA vaccine formulations, we screened for Listeria epitopes presented on the surface of infected human cell lines by mass spectrometry-based immunopeptidomics. In between more than 15,000 human self-peptides, we detected 68 Listeria epitopes from 42 different bacterial proteins, including several known antigens. Peptide epitopes presented on different cell lines were often derived from the same bacterial surface proteins, classifying these antigens as potential vaccine candidates. Encoding these highly presented antigens in lipid nanoparticle mRNA vaccine formulations resulted in high levels of protection in vaccination challenge experiments in mice. Our results pave the way for the development of a clinical mRNA vaccine against Listeria and demonstrate the power of immunopeptidomics for next-generation bacterial vaccine development.
Project description:Expression profiling by microarray was used with a murine listeriosis model to better understand increased susceptibility of preterm neonates to infection. We used DNA microarray to identify genes that were differentially expressed in liver of adult and neonatal Balb/c mice after listeriosis infection. A murine listeriosis model was established. The methods for culturing and counting the Listeria monocytogenes (strain CNL 85/163) had been described in previous publications. The Listeria was injected intraperitoneally using a 1-mL U-100 insulin syringe with a 30 gauge needle. Doses of Listeria monocytogenes used were based on work by our laboratory showing that similar bacterial colony counts were obtained with 4.2 x 10^5 total Listeria per adult mouse and 150 Listeria per gram for 3 to 5 day old neonatal mice. In neonatal mice, great care was taken to void deep intraperitoneal injection towards the viscera, or across the central abdominal vessels. At specified time points, liver was removed upon animal sacrifice and immediately flash frozen in liquid nitrogen and stored at -80 degrees Centigrade. Three adult mice and three neonatal mice were used at each time point.
Project description:Myeloid dendritic cells (DC) and macrophages play an important role in pathogen sensing and antimicrobial defense. Recently we demonstrated that infection of human DC with intracellular bacterium Listeria monocytogenes (L.monocytogenes) leads to the induction of the immunoinhibitory enzyme indoleamine 2,3-dioxygenase (Popov et al., J Clin Invest, 2006), while in the previous studies L.monocytogenes infection was associated with a rather stimulatory DC phenotype. To clarify this discrepancy we performed comparative microarray analysis of immature mo-DC (immDC), mature stimulatory mo-DC (matDC) and mature inhibitory DC either stimulated with prostaglandin E2 (PGE2-DC) or infected with L.monocytogenes (infDC). Studying infection of human myeloid DC with Listeria monocytogenes, we found out, that infected DC are modified by the pathogen to express multiple inhibitory molecules, including indoleamine 2,3-dioxygenase (IDO), cyclooxygenase-2, interleukin 10 and CD25, which acts on DC as IL-2 scavenger. All these inhibitory molecules, expressed on regulatory DC (DCreg), are strictly TNF-dependent and are in concert suppressing T-cell responses. Moreover, only DCreg can efficiently control the number of intracellular listeria, mostly by IDO-mediated mechanisms and by other factors, remaining to be identified. Analyzing publicly acessible data of transcriptional changes in DC and macrophages, infected by various pathogens and parasites (GEO, GSE360), we noticed that infection of these cells with Mycobacterium tuberculosis causes transcriptional response, comparable with the one caused by listeria in human DC. In fact, granuloma in tuberculosis and listeriosis in vivo are enriched for myeloid DC and macrophages characterized by regulatory phenotype. In summary, regulatory myeloid DC and macrophages may play a dual role during life-threatening granulomatous infections, such as tuberculosis: on one hand, regulatory myeloid cells promote pathogen containment by efficiently killing intracellular bacteria, on the other hand these cells inhibit granuloma-associated T cells and thereby might be involved in the retention of TNF-controlled granuloma integrity protecting the host from granuloma break-down and pathogen dissemination. Experiment Overall Design: Transcriptional profiles of immature mo-DC (immDC, n=3), mature stimulatory mo-DC (matDC, n=3) and mature inhibitory mo-DC either stimulated with prostaglandin E2 (PGE2-DC, n=3) or infected with L.monocytogenes (infDC, n=3) were compared on Affymetrix HG-U133A platform. All samples represent biological replicates and were processed separately throughout the experiment.
Project description:Myeloid dendritic cells (DC) and macrophages play an important role in pathogen sensing and antimicrobial defense. Recently we demonstrated that infection of human DC with intracellular bacterium Listeria monocytogenes (L.monocytogenes) leads to the induction of the immunoinhibitory enzyme indoleamine 2,3-dioxygenase (Popov et al., J Clin Invest, 2006), while in the previous studies L.monocytogenes infection was associated with a rather stimulatory DC phenotype. To clarify this discrepancy we performed comparative microarray analysis of immature mo-DC (immDC), mature stimulatory mo-DC (matDC) and mature inhibitory DC either stimulated with prostaglandin E2 (PGE2-DC) or infected with L.monocytogenes (infDC). Studying infection of human myeloid DC with Listeria monocytogenes, we found out, that infected DC are modified by the pathogen to express multiple inhibitory molecules, including indoleamine 2,3-dioxygenase (IDO), cyclooxygenase-2, interleukin 10 and CD25, which acts on DC as IL-2 scavenger. All these inhibitory molecules, expressed on regulatory DC (DCreg), are strictly TNF-dependent and are in concert suppressing T-cell responses. Moreover, only DCreg can efficiently control the number of intracellular listeria, mostly by IDO-mediated mechanisms and by other factors, remaining to be identified. Analyzing publicly acessible data of transcriptional changes in DC and macrophages, infected by various pathogens and parasites (GEO, GSE360), we noticed that infection of these cells with Mycobacterium tuberculosis causes transcriptional response, comparable with the one caused by listeria in human DC. In fact, granuloma in tuberculosis and listeriosis in vivo are enriched for myeloid DC and macrophages characterized by regulatory phenotype. In summary, regulatory myeloid DC and macrophages may play a dual role during life-threatening granulomatous infections, such as tuberculosis: on one hand, regulatory myeloid cells promote pathogen containment by efficiently killing intracellular bacteria, on the other hand these cells inhibit granuloma-associated T cells and thereby might be involved in the retention of TNF-controlled granuloma integrity protecting the host from granuloma break-down and pathogen dissemination. Keywords: Cell type comparison, response to infection