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Participation of the Salmonella OmpD porin in the infection of RAW264.7 macrophages and BALB/c mice.

Ipinza F, Collao B, Monsalva D, Bustamante VH, Luraschi R, Alegría-Arcos M, Almonacid DE, Aguayo D, Calderón IL, Gil F, Santiviago CA, Morales EH, Calva E, Saavedra CP - PLoS ONE (2014)

Bottom Line: In cultured macrophages, a ΔompD strain exhibited increased invasion and proliferation phenotypes as compared to its parental strain.In contrast, overexpression of ompD caused a reduction in bacterial proliferation but did not affect adherence or invasion.Additionally, cultured macrophages infected with the ΔompD strain produced lower levels of reactive oxygen species, suggesting that down-regulation of ompD could favor replication of Salmonella inside macrophages and the subsequent systemic dissemination, by limiting the reactive oxygen species response of the host.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.

ABSTRACT
Salmonella Typhimurium is the etiological agent of gastroenteritis in humans and enteric fever in mice. Inside these hosts, Salmonella must overcome hostile conditions to develop a successful infection, a process in which the levels of porins may be critical. Herein, the role of the Salmonella Typhimurium porin OmpD in the infection process was assessed for adherence, invasion and proliferation in RAW264.7 mouse macrophages and in BALB/c mice. In cultured macrophages, a ΔompD strain exhibited increased invasion and proliferation phenotypes as compared to its parental strain. In contrast, overexpression of ompD caused a reduction in bacterial proliferation but did not affect adherence or invasion. In the murine model, the ΔompD strain showed increased ability to survive and replicate in target organs of infection. The ompD transcript levels showed a down-regulation when Salmonella resided within cultured macrophages and when it colonized target organs in infected mice. Additionally, cultured macrophages infected with the ΔompD strain produced lower levels of reactive oxygen species, suggesting that down-regulation of ompD could favor replication of Salmonella inside macrophages and the subsequent systemic dissemination, by limiting the reactive oxygen species response of the host.

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Related in: MedlinePlus

Expression of S. Typhimurium 14028 s ompD inside macrophages.Transcript levels of ompD (A) and ompW (B) from strain 14028 s were quantified by qRT-PCR by recovering total RNA from the infected macrophages at 1 to 12 h post infection, and from bacteria of the inoculating culture (I). Experiments were performed in triplicate. Asterisks represent significant statistical differences between the control and mutants strains (* p≤0.05; ** p≤0.005;*** p≤0.001). Values are mean ± SD.
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pone-0111062-g002: Expression of S. Typhimurium 14028 s ompD inside macrophages.Transcript levels of ompD (A) and ompW (B) from strain 14028 s were quantified by qRT-PCR by recovering total RNA from the infected macrophages at 1 to 12 h post infection, and from bacteria of the inoculating culture (I). Experiments were performed in triplicate. Asterisks represent significant statistical differences between the control and mutants strains (* p≤0.05; ** p≤0.005;*** p≤0.001). Values are mean ± SD.

Mentions: In order to determine whether ompD expression is repressed when S. Typhimurium resides inside macrophages, the ompD mRNA levels were determined by qRT-PCR in macrophages infected with the wild-type strain at 1 to 12 h post-infection. Transcript levels of ompD obtained from infected macrophages were compared to those from the bacterial inoculum used for infecting cells. As shown in Figure 2A, the ompD mRNA levels were significantly decreased at all times assayed. In contrast, the ompW transcript levels were slightly induced at early times post-infection, which was more evident at 8 and 10 h post-infection (Figure 2B). In agreement with these results, a previous transcriptomic study also showed down-regulation and induction of the ompD (nmpC) and ompW transcript levels, respectively, when Salmonella is inside macrophages [38]. Thus, repression of ompD could be necessary for efficient intracellular proliferation of Salmonella.


Participation of the Salmonella OmpD porin in the infection of RAW264.7 macrophages and BALB/c mice.

Ipinza F, Collao B, Monsalva D, Bustamante VH, Luraschi R, Alegría-Arcos M, Almonacid DE, Aguayo D, Calderón IL, Gil F, Santiviago CA, Morales EH, Calva E, Saavedra CP - PLoS ONE (2014)

Expression of S. Typhimurium 14028 s ompD inside macrophages.Transcript levels of ompD (A) and ompW (B) from strain 14028 s were quantified by qRT-PCR by recovering total RNA from the infected macrophages at 1 to 12 h post infection, and from bacteria of the inoculating culture (I). Experiments were performed in triplicate. Asterisks represent significant statistical differences between the control and mutants strains (* p≤0.05; ** p≤0.005;*** p≤0.001). Values are mean ± SD.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215857&req=5

pone-0111062-g002: Expression of S. Typhimurium 14028 s ompD inside macrophages.Transcript levels of ompD (A) and ompW (B) from strain 14028 s were quantified by qRT-PCR by recovering total RNA from the infected macrophages at 1 to 12 h post infection, and from bacteria of the inoculating culture (I). Experiments were performed in triplicate. Asterisks represent significant statistical differences between the control and mutants strains (* p≤0.05; ** p≤0.005;*** p≤0.001). Values are mean ± SD.
Mentions: In order to determine whether ompD expression is repressed when S. Typhimurium resides inside macrophages, the ompD mRNA levels were determined by qRT-PCR in macrophages infected with the wild-type strain at 1 to 12 h post-infection. Transcript levels of ompD obtained from infected macrophages were compared to those from the bacterial inoculum used for infecting cells. As shown in Figure 2A, the ompD mRNA levels were significantly decreased at all times assayed. In contrast, the ompW transcript levels were slightly induced at early times post-infection, which was more evident at 8 and 10 h post-infection (Figure 2B). In agreement with these results, a previous transcriptomic study also showed down-regulation and induction of the ompD (nmpC) and ompW transcript levels, respectively, when Salmonella is inside macrophages [38]. Thus, repression of ompD could be necessary for efficient intracellular proliferation of Salmonella.

Bottom Line: In cultured macrophages, a ΔompD strain exhibited increased invasion and proliferation phenotypes as compared to its parental strain.In contrast, overexpression of ompD caused a reduction in bacterial proliferation but did not affect adherence or invasion.Additionally, cultured macrophages infected with the ΔompD strain produced lower levels of reactive oxygen species, suggesting that down-regulation of ompD could favor replication of Salmonella inside macrophages and the subsequent systemic dissemination, by limiting the reactive oxygen species response of the host.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.

ABSTRACT
Salmonella Typhimurium is the etiological agent of gastroenteritis in humans and enteric fever in mice. Inside these hosts, Salmonella must overcome hostile conditions to develop a successful infection, a process in which the levels of porins may be critical. Herein, the role of the Salmonella Typhimurium porin OmpD in the infection process was assessed for adherence, invasion and proliferation in RAW264.7 mouse macrophages and in BALB/c mice. In cultured macrophages, a ΔompD strain exhibited increased invasion and proliferation phenotypes as compared to its parental strain. In contrast, overexpression of ompD caused a reduction in bacterial proliferation but did not affect adherence or invasion. In the murine model, the ΔompD strain showed increased ability to survive and replicate in target organs of infection. The ompD transcript levels showed a down-regulation when Salmonella resided within cultured macrophages and when it colonized target organs in infected mice. Additionally, cultured macrophages infected with the ΔompD strain produced lower levels of reactive oxygen species, suggesting that down-regulation of ompD could favor replication of Salmonella inside macrophages and the subsequent systemic dissemination, by limiting the reactive oxygen species response of the host.

Show MeSH
Related in: MedlinePlus