Biomedical subjects

Mari A Smits

Publications and source records attributed to Mari A Smits.

9 recordsLinked to original sources

PubMed2006

Immunological and gene expression responses to a Salmonella infection in the chicken intestine.

Besides infection in humans, Salmonella enteritidis can also cause serious illness in young chickens. However, the genetic and immunological parameters important for the disease in chickens are not well characterized. In this study, processes in the chicken intestine in response to a Salmonella infection were investigated in two different chicken lines. One-day-old chickens were orally infected with Salmonella. T-cell subpopulations, phagocytic properties of intestinal mononuclear cells and RNA expression levels of the jejunum were investigated. The two chicken lines differed in the amount of cfu in the liver and growth retardation after the infection. Differences in phagocytic activity of intestinal mononuclear cells were found between control and Salmonella infected chickens. The number of CD4+ T-cells of the intestine decreased after the Salmonella infection in one chicken line, while the number of CD8+ T-cells increased in both chicken lines, but the time post infection of this increase differed between the lines. In one chicken line the expression levels of the genes carboxypeptidase M and similar to ORF2 decreased after the Salmonella infection, which might be related to a decrease in the amount of macrophages. With the microarray, ten genes were found that were regulated in only one of the chicken lines, while we found six genes regulated in response to the infection in both chicken lines. So differences in genetic background of the chickens influence the intestinal host response of the Salmonella infection as observed by phagocytic activity, gene expression and changes in the number of T-cell subpopulations and macrophages.

Animals↗

PubMed2006

Gene expression responses to a Salmonella infection in the chicken intestine differ between lines.

Poultry products are an important source of Salmonella enterica. An effective way to reduce food poisoning due to Salmonella would be to breed chickens more resistant to Salmonella. Unfortunately host responses to Salmonella are complex with many factors involved. To learn more about responses to Salmonella in young chickens, a cDNA microarray analysis was performed to compare gene expression profiles between two chicken lines under control and Salmonella infected conditions. Newly hatched chickens were orally infected with S. enterica serovar Enteritidis. Since the intestine is the first barrier the bacteria encounter after oral inoculation, intestinal gene expression was investigated at different timepoints. Differences in gene expression between the two chicken lines were found in control as well as Salmonella infected conditions. In response to the Salmonella infection a fast growing chicken broiler line induced genes that affect T-cell activation, whereas in a slow growing broiler line genes involved in macrophage activation seemed to be more affected at day 1 post-infection. At days 7 and 9 most gene expression differences between the two chicken lines were identified under control conditions, indicating a difference in the intestinal development between the two chicken lines which might be linked to the difference in Salmonella susceptibility. The findings in this study have lead to the identification of novel genes and possible cellular pathways, which are host dependent.

Animals↗

PubMed2006

Maternal diet influences gene expression in intestine of offspring in chicken (Gallus gallus).

The diet of the mother during pregnancy influences the onset of different diseases and health-related traits in the offspring. We investigated the influence of the mother hen diet on the intestinal gene expression pattern in the offspring. Hens received for 11 weeks either a commercial feed or a commercial feed supplemented with vitamins and minerals. The offspring of the two groups showed no changes in growth rate or feed conversion. Of this offspring, gene expression patterns in the intestine were measured at 3 and 14 days of age with an intestinal cDNA-microarray. Between the two groups, 11 genes were found to be differentially expressed both at 3 and 14 days of age. Thus, these genes were differently regulated when the intestine is developing as well as when the intestine is more mature. Genes that are differentially expressed at day 3 and/or day 14 affect intestinal turnover, proliferation and development, metabolism and feed absorption. To confirm that differences in gene expression are related to intestinal development, we investigated intestinal proliferation. This indeed also showed differences in proliferation between the two groups at day 3 and day 14 of age. The gene expression and proliferation results indicate that feed of the hens influences the functionality of intestine of the offspring at day 3 and 14 of age.

Animal Nutritional Physiological Phenomena↗

PubMed2006

The early transcriptional response of pig small intestinal mucosa to invasion by Salmonella enterica serovar typhimurium DT104.

Salmonella enterica serovar typhimurium (S. typhimurium) species are a leading cause of human invasive gastroenteritis. There is increasing in vitro evidence about Salmonella interaction with isolated cells or cell lines (macrophages, and enterocytes) on the molecular level, however, very little is known about in vivo interactions during actual invasion. We investigated the early interaction of S. typhimurium with intact small intestinal mucosa, in a pig model. Intestinal segments were infected with or without S. typhimurium DT104, and perfused. Whole mucosal gene expression was analyzed by cDNA array on 0, 2, 4, and 8h post-infection. Invasion resulted in the upregulation of only eight transcripts in jejunal mucosa, among those the proinflammatory IL-8 (at 4h only), and the antiinflammatory STAT3 (at 4 and 8h). The limited number of differentially expressed genes found here in vivo compared to in vitro is most likely due to the presence of multiple, heterogenous cell interactions in intact mucosa. Furthermore, it is concluded that S. typhimurium evades strong host responses by downregulating the local inflammatory response.

Animals↗

PubMed2005

Biodiversity-based identification and functional characterization of the mannose-specific adhesin of Lactobacillus plantarum.

Lactobacillus plantarum is a frequently encountered inhabitant of the human intestinal tract, and some strains are marketed as probiotics. Their ability to adhere to mannose residues is a potentially interesting characteristic with regard to proposed probiotic features such as colonization of the intestinal surface and competitive exclusion of pathogens. In this study, the variable capacity of 14 L. plantarum strains to agglutinate Saccharomyces cerevisiae in a mannose-specific manner was determined and subsequently correlated with an L. plantarum WCFS1-based genome-wide genotype database. This led to the identification of four candidate mannose adhesin-encoding genes. Two genes primarily predicted to code for sortase-dependent cell surface proteins displayed a complete gene-trait match. Their involvement in mannose adhesion was corroborated by the finding that a sortase (srtA) mutant of L. plantarum WCFS1 lost the capacity to agglutinate S. cerevisiae. The postulated role of these two candidate genes was investigated by gene-specific deletion and overexpression in L. plantarum WCFS1. Subsequent evaluation of the mannose adhesion capacity of the resulting mutant strains showed that inactivation of one candidate gene (lp_0373) did not affect mannose adhesion properties. In contrast, deletion of the other gene (lp_1229) resulted in a complete loss of yeast agglutination ability, while its overexpression quantitatively enhanced this phenotype. Therefore, this gene was designated to encode the mannose-specific adhesin (Msa; gene name, msa) of L. plantarum. Domain homology analysis of the predicted 1,000-residue Msa protein identified known carbohydrate-binding domains, further supporting its role as a mannose adhesin that is likely to be involved in the interaction of L. plantarum with its host in the intestinal tract.

Adhesins, Bacterial↗

PubMed2004

Both ApxI and ApxII of Actinobacillus pleuropneumoniae serotype 1 are necessary for full virulence.

Most serotypes of A. pleuropneumoniae produce more than one toxin in vivo. To determine the value of the production of more than one toxin in the development of disease, we tested the pathogenicity of isogenic strains of A. pleuropneumoniae serotype 1 that are mutated in the toxin genes apxIA and/or apxIIA or in the transport genes apxIBD. Bacteria mutated in both apxIA and apxIIA, or in apxIBD, were unable to induce pathological lesions, thereby confirming the conclusion that ApxI and ApxII are essential for the pathogenesis of pleuropneumonia. Infection with isogenic strains lacking either ApxI or ApxII did not consistently lead to pleuropneumonia unlike the parent strain S4074. ApxII seemed at least as important as ApxI for the development of clinical and pathological symptoms. Only one of the four pigs inoculated with a mutant strain unable to produce ApxII developed mild pneumonia whereas two out of the three pigs inoculated with a mutant strain unable to produce ApxI developed more severe lesions. The results indicate that both ApxI and ApxII of A. pleuropneumoniae serotype 1 are necessary for full virulence.

Actinobacillus Infections↗

PubMed2003

In vitro conversion of normal prion protein into pathologic isoforms.

The in vitro conversion techniques in cell-free and cell culture systems have provided tools to adequately study the underlying mechanism of TSEs, namely PrP conversion. These systems also have provided tools that make it easier to study the interspecies and intraspecies transmissibilities of TSEs. Finally, these systems also may assist in the discovery of TSE therapeutic strategies and in the development of extremely sensitive TSE detection techniques. In vivo TSE transmission studies are limited to (transgenic) animals (mostly mice). Although the cell culture systems also are restricted in their species-range (mostly mouse), the currently used cell-free systems. Allow studying almost all possible species barriers (including the potential transmission of various TSEs to humans). One advantage of the cell culture systems, however, is that they generate do novo TSE infectivity. Studies using cell cultures also take into account several cofactors in addition to PrP that might be involved in replication the TSE agent. Although the in vitro systems provide accurate tools to study TSE agent parameters, they mainly or only focus on the molecular processes of PrP conversion. Other factors (i.e., host genetic factors [99]) that, for example, determine the differential uptake of the TSE agent from the environment, might play an additional role in determining the susceptibility of hosts for TSEs and on the transmission of the disease among individuals.

Animals↗

PubMed2003

Generation of EST and microarray resources for functional genomic studies on chicken intestinal health.

Expressed sequenced tags (ESTs) and microarray resources have a great impact on the ability to study host response in mice and humans. Unfortunately, these resources are not yet available for domestic farm animals. The aim of this study was to provide genomic resources to study chicken intestinal health, in particular malabsorption syndrome (MAS), which affects mainly the intestine. Therefore a normalized and subtracted cDNA library containing more than 7000 clones was prepared. Randomly chosen clones were sequenced for control purposes. New ESTs were found and multiple ESTs not identified in the chicken intestine before were observed. The number of non-specific ESTs in this cDNA library was low. Based on this normalized and subtracted library a cDNA microarray was made. In a preliminary hybridization experiment with the microarray, genes were identified to be up- or downregulated in MAS infected chickens. This indicates that the generated resources are valuable tools to investigate chicken intestinal health by whole genome expression analysis approaches.

Animals↗

PubMed2001

Environmentally regulated genes of Streptococcus suis: identification by the use of iron-restricted conditions in vitro and by experimental infection of piglets.

The identification of environmentally regulated genes of Streptococcus suis by the use of iron-restricted conditions in vitro and by experimental infection of piglets is described. Eighteen unique iron-restriction-induced (iri) genes and 22 unique in-vivo-selected (ivs) genes of Strep. suis were found. None of the ivs genes was exclusively expressed in vivo. Four iri genes were identical to four clones selected in piglets. Two ivs genes were similar to genes for putative virulence factors. One of these ivs genes was identical to the epf gene of virulent Strep. suis serotype 2 strains and the other showed homology to a gene encoding a fibronectin-binding protein of Streptococcus gordonii. Two additional ivs genes showed homology to environmentally regulated genes previously identified by using an in vivo expression technology (IVET) selection system in other bacterial species. One of these showed similarity to the agrA gene of Staphylococcus aureus, a key locus involved in the regulation of numerous virulence proteins. The promoter selection system described in this paper has been successfully used for the identification of many environmentally regulated genes potentially involved in the pathogenesis of Strep. suis infections in piglets.

Animals↗