Inhibition of
            <i>Salmonella</i>
            Host Cell Invasion by Dimethyl Sulfide

Antunes, L. Caetano M.; Buckner, Michelle M. C.; Auweter, Sigrid; Ferreira, Rosana B. R.; Lolić, Petra

doi:10.1128/aem.00851-10

Cited by 24 publications

(29 citation statements)

References 27 publications

(34 reference statements)

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“…Cultures were incubated at 37°C or 42°C until an OD 600 of ϳ1 was reached (ϳ5.5 h after dilution). When expression studies used derivatives of the rifampin-resistant S. Enteritidis BTNC0025 strain, to avoid SPI-1 repression through metabolism of the solvent DMSO, rifampin was not added (14,23). A 20-ml volume of cold RNAlater solution (Life Technologies, Grand Island, NY) was added to stabilize RNA.…”

Section: Methodsmentioning

confidence: 99%

“…␤-Galactosidase activity was measured in stationary-phase cells following overnight growth (approximately 16 to 18 h) under the specified conditions, and, when appropriate, cells were pelleted from a portion of the sample and prepared for SDS-PAGE as described below. When expression studies used derivatives of rifampin-resistant S. Enteritidis strain BTNC0025, to avoid SPI-1 repression through metabolism of the solvent dimethyl sulfoxide (DMSO), rifampin was not added (14,23).…”

Section: Methodsmentioning

confidence: 99%

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Poultry Body Temperature Contributes to Invasion Control through Reduced Expression of Salmonella Pathogenicity Island 1 Genes in Salmonella enterica Serovars Typhimurium and Enteritidis

Troxell

Petri

Daron

et al. 2015

Appl Environ Microbiol

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b Salmonella enterica serovars Typhimurium (S. Typhimurium) and Enteritidis (S. Enteritidis) are foodborne pathogens, and outbreaks are often associated with poultry products. Chickens are typically asymptomatic when colonized by these serovars; however, the factors contributing to this observation are uncharacterized. Whereas symptomatic mammals have a body temperature between 37°C and 39°C, chickens have a body temperature of 41°C to 42°C. Here, in vivo experiments using chicks demonstrated that numbers of viable S. Typhimurium or S. Enteritidis bacteria within the liver and spleen organ sites were >4 orders of magnitude lower than those within the ceca. When similar doses of S. Typhimurium or S. Enteritidis were given to C3H/HeN mice, the ratio of the intestinal concentration to the liver/spleen concentration was 1:1. In the avian host, this suggested poor survival within these tissues or a reduced capacity to traverse the host epithelial layer and reach liver/spleen sites or both. Salmonella pathogenicity island 1 (SPI-1) promotes localization to liver/spleen tissues through invasion of the epithelial cell layer. Following in vitro growth at 42°C, SPI-1 genes sipC, invF, and hilA and the SPI-1 rtsA activator were downregulated compared to expression at 37°C. Overexpression of the hilA activators fur, fliZ, and hilD was capable of inducing hilA-lacZ at 37°C but not at 42°C despite the presence of similar levels of protein at the two temperatures. In contrast, overexpression of either hilC or rtsA was capable of inducing hilA and sipC at 42°C. These data indicate that physiological parameters of the poultry host, such as body temperature, have a role in modulating expression of virulence. Salmonella enterica serovars Typhimurium (S. Typhimurium) and Enteritidis (S. Enteritidis) are major causes of foodborne diseases worldwide. In the United States, S. Typhimurium and S. Enteritidis accounted for the majority of confirmed cases of Salmonella outbreaks between 1970 and 2011 (1). These two are nontyphoid Salmonella (NTS) serovars that are capable of causing disease signs in a variety of animals, which contrasts with typhoid fever serovars that exclusively infect humans. Numerous food products have been associated with Salmonella outbreaks and illnesses in humans; however, poultry products are frequently implicated in outbreaks associated with NTS (www.cdc.gov /Salmonella/outbreaks.html). In 2010, a major poultry-related outbreak occurred that involved S. Enteritidis infections across 11 states and resulted in the recall of 380 million eggs (2).S. Typhimurium invades the host epithelial cell layer and migrates to liver and spleen tissue sites through the action of a type 3 secretion system (T3SS), encoded by Salmonella pathogenicity island 1 (SPI-1). SPI-1 is a DNA segment that is approximately 40 kb in size and encodes the structural components of the secretion system, secreted and chaperone proteins, and transcription factors that activate expression of the SPI-1 genes (3-5). Three regulators that are carried wi...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Poultry Body Temperature Contributes to Invasion Control through Reduced Expression of Salmonella Pathogenicity Island 1 Genes in Salmonella enterica Serovars Typhimurium and Enteritidis

Troxell

Petri

Daron

et al. 2015

Appl Environ Microbiol

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“…In order to monitor the effect of bile or bile components on hilA or phoP expression, we amplified DNA fragments containing the promoters of hilA (Ϫ675 through ϩ70, relative to the translational start codon) and phoP (Ϫ163 through ϩ33, relative to the translational start codon) through PCR and independently cloned them upstream of the promoterless green fluorescent protein (GFP) gene gfp of pFPV25 (40) using the SacI and BamHI restriction sites and standard cloning procedures, as described elsewhere (2,33). The primers used are shown on Table 1.…”

Section: Chemicalsmentioning

confidence: 99%

Repression of Salmonella entericaphoPExpression by Small Molecules from Physiological Bile

et al. 2012

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Infection with Salmonella enterica serovar Typhi in humans causes the life-threatening disease typhoid fever. In the laboratory, typhoid fever can be modeled through the inoculation of susceptible mice with Salmonella enterica serovar Typhimurium. Using this murine model, we previously characterized the interactions between Salmonella Typhimurium and host cells in the gallbladder and showed that this pathogen can successfully invade gallbladder epithelial cells and proliferate. Additionally, we showed that Salmonella Typhimurium can use bile phospholipids to grow at high rates. These abilities are likely important for quick colonization of the gallbladder during typhoid fever and further pathogen dissemination through fecal shedding. To further characterize the interactions between Salmonella and the gallbladder environment, we compared the transcriptomes of Salmonella cultures grown in LB broth or physiological murine bile. Our data showed that many genes involved in bacterial central metabolism are affected by bile, with the citric acid cycle being repressed and alternative respiratory systems being activated. Additionally, our study revealed a new aspect of Salmonella interactions with bile through the identification of the global regulator phoP as a bile-responsive gene. Repression of phoP expression could also be achieved using physiological, but not commercial, bovine bile. The biological activity does not involve PhoPQ sensing of a bile component and is not caused by bile acids, the most abundant organic components of bile. Bioactivity-guided purification allowed the identification of a subset of small molecules from bile that can elicit full activity; however, a single compound with phoP inhibitory activity could not be isolated, suggesting that multiple molecules may act in synergy to achieve this effect. Due to the critical role of phoP in Salmonella virulence, further studies in this area will likely reveal aspects of the interaction between Salmonella and bile that are relevant to disease.

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“…6 shows that this concentration is somewhere between 1 and 10 M. To further ascertain that 3,4-dimethylbenzoic acid is a repressor of hilA, we set out to confirm the results reported above using a different methodology. Although the PhilA::gfp reporter strain employed in our studies has been successfully used to determine the effects of environmental cues on hilA expression (19,20), it is based on a multicopy-plasmid system, and, as such, it may not reflect the actual levels of hilA mRNA and the real fold changes elicited by any given stimulus. Therefore, we repeated the same experiment, growing Salmonella in the absence or presence of 100 M 3,4-dimethylbenzoic acid to assess hilA expression; this time, however, we used the wild-type Salmonella strain SL1344 and measured hilA expression through real-time Figure 6C shows that, indeed, 3,4-dimethylbenzoic acid represses hilA expression, and to a further extent than what was observed in the GFP reporter experiments.…”

Section: Figmentioning

confidence: 99%

Repression of Salmonella Host Cell Invasion by Aromatic Small Molecules from the Human Fecal Metabolome

Peixoto

Alves

Wang

et al. 2017

Appl Environ Microbiol

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The human microbiome is a collection of microorganisms that inhabit every surface of the body that is exposed to the environment, generally coexisting peacefully with their host. These microbes have important functions, such as producing vitamins, aiding in maturation of the immune system, and protecting against pathogens. We have previously shown that a small-molecule extract from the human fecal microbiome has a strong repressive effect on Salmonella enterica serovar Typhimurium host cell invasion by modulating the expression of genes involved in this process. Here, we describe the characterization of this biological activity. Using a series of purification methods, we obtained fractions with biological activity and characterized them by mass spectrometry. These experiments revealed an abundance of aromatic compounds in the bioactive fraction. Selected compounds were obtained from commercial sources and tested with respect to their ability to repress the expression of hilA, the gene encoding the master regulator of invasion genes in Salmonella. We found that the aromatic compound 3,4-dimethylbenzoic acid acts as a strong inhibitor of hilA expression and of invasion of cultured host cells by Salmonella. Future studies should reveal the molecular details of this phenomenon, such as the signaling cascades involved in sensing this bioactive molecule.IMPORTANCE Microbes constantly sense and adapt to their environment. Often, this is achieved through the production and sensing of small extracellular molecules. The human body is colonized by complex communities of microbes, and, given their biological and chemical diversity, these ecosystems represent a platform where the production and sensing of molecules occur. In previous work, we showed that small molecules produced by microbes from the human gut can significantly impair the virulence of the enteric pathogen Salmonella enterica. Here, we describe a specific compound from the human gut that produces this same effect. The results from this work not only shed light on an important biological phenomenon occurring in our bodies but also may represent an opportunity to develop drugs that can target these small-molecule interactions to protect us from enteric infections and other diseases.

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Inhibition of Salmonella Host Cell Invasion by Dimethyl Sulfide

Cited by 24 publications

References 27 publications

Poultry Body Temperature Contributes to Invasion Control through Reduced Expression of Salmonella Pathogenicity Island 1 Genes in Salmonella enterica Serovars Typhimurium and Enteritidis

Poultry Body Temperature Contributes to Invasion Control through Reduced Expression of Salmonella Pathogenicity Island 1 Genes in Salmonella enterica Serovars Typhimurium and Enteritidis

Repression of Salmonella entericaphoPExpression by Small Molecules from Physiological Bile

Repression of Salmonella Host Cell Invasion by Aromatic Small Molecules from the Human Fecal Metabolome

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