Limits...
Gram-negative and Gram-positive bacterial infections give rise to a different metabolic response in a mouse model.

Hoerr V, Zbytnuik L, Leger C, Tam PP, Kubes P, Vogel HJ - J. Proteome Res. (2012)

Bottom Line: In an attempt to develop a better understanding of the process of pathogenesis and the associated host response we have used a quantitative (1)H NMR approach to study the metabolic response to different bacterial infections.Multivariate statistical analysis revealed correlations between metabolic, cytokine and physiological responses.Since Gram-positive and Gram-negative bacteria activate different receptor pathways in the host, our results suggest that it may become possible in the future to use a metabolomics approach to improve on current clinical microbiology diagnostic methods.

View Article: PubMed Central - PubMed

Affiliation: Biochemistry Research Group, Department of Biological Sciences, ‡Department of Physiology and Biophysics, Snyder Institute, University of Calgary , Calgary, Alberta T2N 1N4, Canada.

ABSTRACT
Metabolomics has become an important tool to study host-pathogen interactions and to discover potential novel therapeutic targets. In an attempt to develop a better understanding of the process of pathogenesis and the associated host response we have used a quantitative (1)H NMR approach to study the metabolic response to different bacterial infections. Here we describe that metabolic changes found in serum of mice that were infected with Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli and Pseudomonas aeruginosa can distinguish between infections caused by Gram-positive and Gram-negative bacterial strains. By combining the results of the mouse study with those of bacterial footprinting culture experiments, bacterially secreted metabolites could be identified as potential bacterium-specific biomarkers for P. aeruginosa infections but not for the other strains. Multivariate statistical analysis revealed correlations between metabolic, cytokine and physiological responses. In TLR4 and TLR2 knockout mice, host-response pathway correlated metabolites could be identified and allowed us for the first time to distinguish between bacterial- and host-induced metabolic changes. Since Gram-positive and Gram-negative bacteria activate different receptor pathways in the host, our results suggest that it may become possible in the future to use a metabolomics approach to improve on current clinical microbiology diagnostic methods.

Show MeSH

Related in: MedlinePlus

Bacterial exometabolomeand metabolic host response to P. aeruginosa infectedC57BL/6 wild-type mice 24 h post-infection.Some of the elevated serum metabolites of P. aeruginosa infected mice were identified as part of the bacterial exometabolome.(A) Coefficient plot generated from OPLS-DA analysis of the samplesfrom the P. aeruginosa mouse model and control animalsrepresenting the relative contribution that each metabolite makesto the distinction between the two classes (two components; R2 = 1.00,Q2 = 0.99). Highlighted metabolites (red circles) were elevated bothin serum samples of infected mice and in the footprints of P. aeruginosa cultures grown in LB medium. Tryptophan, lysine,threonine, valine, and phenylalanine were significantly elevated bothin vivo and in the bacterial culture media (p <0.05). (B) Metabolite levels of tryptophan, lysine, threonine, valine,and phenylalanine found in serum of mice infected with P.aeruginosa concentrations of 7 × 102, 8 ×104, 1 × 106, and 5 × 106 CFU/mL. Bar charts showing (C) metabolite levels of taurine, ethanol,and creatine and (D) blood leukocyte counts from serum of P. aeruginosa infected mice as a function of different bacterialconcentrations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3368387&req=5

fig4: Bacterial exometabolomeand metabolic host response to P. aeruginosa infectedC57BL/6 wild-type mice 24 h post-infection.Some of the elevated serum metabolites of P. aeruginosa infected mice were identified as part of the bacterial exometabolome.(A) Coefficient plot generated from OPLS-DA analysis of the samplesfrom the P. aeruginosa mouse model and control animalsrepresenting the relative contribution that each metabolite makesto the distinction between the two classes (two components; R2 = 1.00,Q2 = 0.99). Highlighted metabolites (red circles) were elevated bothin serum samples of infected mice and in the footprints of P. aeruginosa cultures grown in LB medium. Tryptophan, lysine,threonine, valine, and phenylalanine were significantly elevated bothin vivo and in the bacterial culture media (p <0.05). (B) Metabolite levels of tryptophan, lysine, threonine, valine,and phenylalanine found in serum of mice infected with P.aeruginosa concentrations of 7 × 102, 8 ×104, 1 × 106, and 5 × 106 CFU/mL. Bar charts showing (C) metabolite levels of taurine, ethanol,and creatine and (D) blood leukocyte counts from serum of P. aeruginosa infected mice as a function of different bacterialconcentrations.

Mentions: For P. aeruginosa,in contrast, metabolomic footprints displayed increased concentrationsfor a variety of different amino acids, while positive contributorsderived from anaerobic or aerobic energy metabolism were not discovered.A comparison of the metabolic profiles with those from serum of P. aeruginosa infected mice showed similarities for a largenumber of metabolites (Figure 4A), indicatingthat P. aeruginosa secretes specific metaboliteswhich contribute directly to the serum metabolome. In subsequent experiments, P. aeruginosa suspensions were injected at different concentrations(7 × 102, 8 × 104, 1 × 106, 5 × 106 CFU/mL) to investigate the effectsof increasing bacterial load and disease stages in the mouse model.Even though MPO and leukocyte counts in the peritoneal lavage increasedsignificantly beginning with a bacterial concentration of 1 ×106 CFU/mL, no significant changes in WBC or severe diseasesymptoms as illustrated by the neutrophil-lymphocyte ratio in Figure 4D were induced for the first three bacterial concentrations.However, serum levels of the five significantly elevated metabolitestryptophan, lysine, threonine, valine, and phenylalanine continuouslyincreased in serum with higher number of bacteria. This indicatesthat these metabolites may be released by the bacteria as bacterialfootprints into the bodily fluids (Figure 4B). On the other hand, a more profound host response was observedwhen a P. aeruginosa suspension with a concentrationof 5 × 106 CFU/mL was applied. At 24 h post administration,these mice developed signs of severe sickness (decreased WBC, increasedneutrophil-lymphocyte ratio) and also experienced decreased serumamino acid levels (Figure 4B) as well as elevatedserum concentrations of ethanol, taurine, and creatine (Figure 4C) and a mortality rate of 50%.


Gram-negative and Gram-positive bacterial infections give rise to a different metabolic response in a mouse model.

Hoerr V, Zbytnuik L, Leger C, Tam PP, Kubes P, Vogel HJ - J. Proteome Res. (2012)

Bacterial exometabolomeand metabolic host response to P. aeruginosa infectedC57BL/6 wild-type mice 24 h post-infection.Some of the elevated serum metabolites of P. aeruginosa infected mice were identified as part of the bacterial exometabolome.(A) Coefficient plot generated from OPLS-DA analysis of the samplesfrom the P. aeruginosa mouse model and control animalsrepresenting the relative contribution that each metabolite makesto the distinction between the two classes (two components; R2 = 1.00,Q2 = 0.99). Highlighted metabolites (red circles) were elevated bothin serum samples of infected mice and in the footprints of P. aeruginosa cultures grown in LB medium. Tryptophan, lysine,threonine, valine, and phenylalanine were significantly elevated bothin vivo and in the bacterial culture media (p <0.05). (B) Metabolite levels of tryptophan, lysine, threonine, valine,and phenylalanine found in serum of mice infected with P.aeruginosa concentrations of 7 × 102, 8 ×104, 1 × 106, and 5 × 106 CFU/mL. Bar charts showing (C) metabolite levels of taurine, ethanol,and creatine and (D) blood leukocyte counts from serum of P. aeruginosa infected mice as a function of different bacterialconcentrations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368387&req=5

fig4: Bacterial exometabolomeand metabolic host response to P. aeruginosa infectedC57BL/6 wild-type mice 24 h post-infection.Some of the elevated serum metabolites of P. aeruginosa infected mice were identified as part of the bacterial exometabolome.(A) Coefficient plot generated from OPLS-DA analysis of the samplesfrom the P. aeruginosa mouse model and control animalsrepresenting the relative contribution that each metabolite makesto the distinction between the two classes (two components; R2 = 1.00,Q2 = 0.99). Highlighted metabolites (red circles) were elevated bothin serum samples of infected mice and in the footprints of P. aeruginosa cultures grown in LB medium. Tryptophan, lysine,threonine, valine, and phenylalanine were significantly elevated bothin vivo and in the bacterial culture media (p <0.05). (B) Metabolite levels of tryptophan, lysine, threonine, valine,and phenylalanine found in serum of mice infected with P.aeruginosa concentrations of 7 × 102, 8 ×104, 1 × 106, and 5 × 106 CFU/mL. Bar charts showing (C) metabolite levels of taurine, ethanol,and creatine and (D) blood leukocyte counts from serum of P. aeruginosa infected mice as a function of different bacterialconcentrations.
Mentions: For P. aeruginosa,in contrast, metabolomic footprints displayed increased concentrationsfor a variety of different amino acids, while positive contributorsderived from anaerobic or aerobic energy metabolism were not discovered.A comparison of the metabolic profiles with those from serum of P. aeruginosa infected mice showed similarities for a largenumber of metabolites (Figure 4A), indicatingthat P. aeruginosa secretes specific metaboliteswhich contribute directly to the serum metabolome. In subsequent experiments, P. aeruginosa suspensions were injected at different concentrations(7 × 102, 8 × 104, 1 × 106, 5 × 106 CFU/mL) to investigate the effectsof increasing bacterial load and disease stages in the mouse model.Even though MPO and leukocyte counts in the peritoneal lavage increasedsignificantly beginning with a bacterial concentration of 1 ×106 CFU/mL, no significant changes in WBC or severe diseasesymptoms as illustrated by the neutrophil-lymphocyte ratio in Figure 4D were induced for the first three bacterial concentrations.However, serum levels of the five significantly elevated metabolitestryptophan, lysine, threonine, valine, and phenylalanine continuouslyincreased in serum with higher number of bacteria. This indicatesthat these metabolites may be released by the bacteria as bacterialfootprints into the bodily fluids (Figure 4B). On the other hand, a more profound host response was observedwhen a P. aeruginosa suspension with a concentrationof 5 × 106 CFU/mL was applied. At 24 h post administration,these mice developed signs of severe sickness (decreased WBC, increasedneutrophil-lymphocyte ratio) and also experienced decreased serumamino acid levels (Figure 4B) as well as elevatedserum concentrations of ethanol, taurine, and creatine (Figure 4C) and a mortality rate of 50%.

Bottom Line: In an attempt to develop a better understanding of the process of pathogenesis and the associated host response we have used a quantitative (1)H NMR approach to study the metabolic response to different bacterial infections.Multivariate statistical analysis revealed correlations between metabolic, cytokine and physiological responses.Since Gram-positive and Gram-negative bacteria activate different receptor pathways in the host, our results suggest that it may become possible in the future to use a metabolomics approach to improve on current clinical microbiology diagnostic methods.

View Article: PubMed Central - PubMed

Affiliation: Biochemistry Research Group, Department of Biological Sciences, ‡Department of Physiology and Biophysics, Snyder Institute, University of Calgary , Calgary, Alberta T2N 1N4, Canada.

ABSTRACT
Metabolomics has become an important tool to study host-pathogen interactions and to discover potential novel therapeutic targets. In an attempt to develop a better understanding of the process of pathogenesis and the associated host response we have used a quantitative (1)H NMR approach to study the metabolic response to different bacterial infections. Here we describe that metabolic changes found in serum of mice that were infected with Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli and Pseudomonas aeruginosa can distinguish between infections caused by Gram-positive and Gram-negative bacterial strains. By combining the results of the mouse study with those of bacterial footprinting culture experiments, bacterially secreted metabolites could be identified as potential bacterium-specific biomarkers for P. aeruginosa infections but not for the other strains. Multivariate statistical analysis revealed correlations between metabolic, cytokine and physiological responses. In TLR4 and TLR2 knockout mice, host-response pathway correlated metabolites could be identified and allowed us for the first time to distinguish between bacterial- and host-induced metabolic changes. Since Gram-positive and Gram-negative bacteria activate different receptor pathways in the host, our results suggest that it may become possible in the future to use a metabolomics approach to improve on current clinical microbiology diagnostic methods.

Show MeSH
Related in: MedlinePlus