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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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Effect of OmpD in systemic infection.(A) Bacteremia assays. Groups of six BALB/c mice were orally inoculated with 103 bacteria of strains 14028 s, ΔompD or ΔompW (n = 6). CFU/ml were determined from samples of peripheral blood obtained after 3 and 5 days post infection. Values are mean ± SD. Asterisks represent statistical significant differences (T-test, * p≤0.05). (B to G) CI assays. A mixture (1∶1 ratio) of 103 bacteria of strains 14028 s (WT) and ΔompD (B and E), ΔompW (C and F) or ΔssrB (D and G) was orally (B, C and D) or intraperitoneally (E, F and G) inoculated to groups of six BALBc mice (n = 6). Liver and spleen were extracted from mice 5 days post infection and the CFU per g of organ was determined for the wild-type strain and the respective mutant. Each data point represents the competitive index (CI), which is the ratio of mutant/WT of recovered CFU/g tissue in the respective organ from each mouse. Horizontal bars represent the median values of ratios for the organ type.
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pone-0111062-g004: Effect of OmpD in systemic infection.(A) Bacteremia assays. Groups of six BALB/c mice were orally inoculated with 103 bacteria of strains 14028 s, ΔompD or ΔompW (n = 6). CFU/ml were determined from samples of peripheral blood obtained after 3 and 5 days post infection. Values are mean ± SD. Asterisks represent statistical significant differences (T-test, * p≤0.05). (B to G) CI assays. A mixture (1∶1 ratio) of 103 bacteria of strains 14028 s (WT) and ΔompD (B and E), ΔompW (C and F) or ΔssrB (D and G) was orally (B, C and D) or intraperitoneally (E, F and G) inoculated to groups of six BALBc mice (n = 6). Liver and spleen were extracted from mice 5 days post infection and the CFU per g of organ was determined for the wild-type strain and the respective mutant. Each data point represents the competitive index (CI), which is the ratio of mutant/WT of recovered CFU/g tissue in the respective organ from each mouse. Horizontal bars represent the median values of ratios for the organ type.

Mentions: To determine whether the detrimental effect of OmpD in the intracellular survival of S. Typhimurium is retained during the systemic infection, the bacteremia in mice at 3 and 5 days post-infection was assessed. For this purpose, groups of BALB/c mice were independently infected by the oral route with strains ΔompD, ΔompW or 14028 s at a dose of 103 CFU and then bacteria were recovered from the circulating blood at various times to quantify the CFU (Figure 4A). The concentration of the ΔompD strain in blood exceeded that of the wild-type strain by more than 2×104 CFU/ml (2-fold increase). No difference in bacteremia was observed between the ΔompW and the wild-type strains.


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)

Effect of OmpD in systemic infection.(A) Bacteremia assays. Groups of six BALB/c mice were orally inoculated with 103 bacteria of strains 14028 s, ΔompD or ΔompW (n = 6). CFU/ml were determined from samples of peripheral blood obtained after 3 and 5 days post infection. Values are mean ± SD. Asterisks represent statistical significant differences (T-test, * p≤0.05). (B to G) CI assays. A mixture (1∶1 ratio) of 103 bacteria of strains 14028 s (WT) and ΔompD (B and E), ΔompW (C and F) or ΔssrB (D and G) was orally (B, C and D) or intraperitoneally (E, F and G) inoculated to groups of six BALBc mice (n = 6). Liver and spleen were extracted from mice 5 days post infection and the CFU per g of organ was determined for the wild-type strain and the respective mutant. Each data point represents the competitive index (CI), which is the ratio of mutant/WT of recovered CFU/g tissue in the respective organ from each mouse. Horizontal bars represent the median values of ratios for the organ type.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0111062-g004: Effect of OmpD in systemic infection.(A) Bacteremia assays. Groups of six BALB/c mice were orally inoculated with 103 bacteria of strains 14028 s, ΔompD or ΔompW (n = 6). CFU/ml were determined from samples of peripheral blood obtained after 3 and 5 days post infection. Values are mean ± SD. Asterisks represent statistical significant differences (T-test, * p≤0.05). (B to G) CI assays. A mixture (1∶1 ratio) of 103 bacteria of strains 14028 s (WT) and ΔompD (B and E), ΔompW (C and F) or ΔssrB (D and G) was orally (B, C and D) or intraperitoneally (E, F and G) inoculated to groups of six BALBc mice (n = 6). Liver and spleen were extracted from mice 5 days post infection and the CFU per g of organ was determined for the wild-type strain and the respective mutant. Each data point represents the competitive index (CI), which is the ratio of mutant/WT of recovered CFU/g tissue in the respective organ from each mouse. Horizontal bars represent the median values of ratios for the organ type.
Mentions: To determine whether the detrimental effect of OmpD in the intracellular survival of S. Typhimurium is retained during the systemic infection, the bacteremia in mice at 3 and 5 days post-infection was assessed. For this purpose, groups of BALB/c mice were independently infected by the oral route with strains ΔompD, ΔompW or 14028 s at a dose of 103 CFU and then bacteria were recovered from the circulating blood at various times to quantify the CFU (Figure 4A). The concentration of the ΔompD strain in blood exceeded that of the wild-type strain by more than 2×104 CFU/ml (2-fold increase). No difference in bacteremia was observed between the ΔompW and the wild-type strains.

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