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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.

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Physiological and immunological conditionsin response to bacterialinfections and to LPS and MALP2 administration, 24 h post-infection.C57BL/6 wild-type mice were infected intraperitoneally with 1 mL of S. aureus (S.a.), S. pneumoniae (S.p.), E. coli (E.c.), and P. aeruginosa (P.a.)suspensions. Saline, LPS, and MALP2 were also ip-injected. (A) Weightloss, MPO activity from lung tissue and leukocyte counts from bothblood and peritoneal lavage. Significance of paired t tests on differences in physiological parameters between controlsand infected mice (1) p < 0.01, (2) p < 0.002, (3) p < 0.05. White blood cell countsdid not differ significantly between the control group and infectedmice. (B) Levels of cytokines and chemokines in mouse serum.
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fig2: Physiological and immunological conditionsin response to bacterialinfections and to LPS and MALP2 administration, 24 h post-infection.C57BL/6 wild-type mice were infected intraperitoneally with 1 mL of S. aureus (S.a.), S. pneumoniae (S.p.), E. coli (E.c.), and P. aeruginosa (P.a.)suspensions. Saline, LPS, and MALP2 were also ip-injected. (A) Weightloss, MPO activity from lung tissue and leukocyte counts from bothblood and peritoneal lavage. Significance of paired t tests on differences in physiological parameters between controlsand infected mice (1) p < 0.01, (2) p < 0.002, (3) p < 0.05. White blood cell countsdid not differ significantly between the control group and infectedmice. (B) Levels of cytokines and chemokines in mouse serum.

Mentions: In our study, we investigated host-microbe interactionsusing twoGram-positive and two Gram-negative organisms: S. aureus, S. pneumonia, E. coli, and P. aeruginosa. The bacterial dose was adjusted to 107 CFU/mL for S. aureus, S. pneumoniae, and E. coli and 106 CFU/mL for P. aeruginosa and resulted in a survival rate of 100% onday one post injection. Twenty-four hours post bacteria administration,mice (n = 8 for each kind of infection) showed CFUsin the lungs (results not shown) as a result of a systemic progressionof the bacterial infection. Additionally, mice were examined accordingto their health condition and status of inflammation by comparingbody weight, Myeloperoxidase (MPO) activity in the lungs, white bloodcell counts in blood and peritoneal lavage, as well as cytokine/chemokinelevels (IL-6, IL-10, G-CSF, KC, MCP-1, MIP-1a, RANTES, TNFa) in serum(Figure 2). The data were compared with shammice (ip injection of 1 mL of saline, n = 7) andanimals having obtained an intraperitoneal injection of LPS (n = 8) and MALP2 (n = 6). For LPS and MALP2,a dose of 0.5 mg/kg and 5 μg/mouse dissolved in a volume of200 μL saline was applied, respectively. Twenty-four h afterinfection, some animals showed signs of diarrhea and stopped eatingand drinking, which resulted in a higher weight loss compared to thecontrol group (Figure 2A). All infected micedeveloped to a similar extent significantly elevated leukocyte countsin the peritoneal lavage (p < 0.01) as well asincreased MPO activity (p < 0.05) in the lungsas a result of neutrophilic influx while white blood counts in blooddid not change significantly compared to the controls. In addition,animals showed enhanced serum levels of different cytokines (IL-6,IL-10, G-CSF, and TNFa) and chemokines (KC, MCP-1, MIP-1a, RANTES)demonstrating that an intense systemic inflammatory response has developed(Figure 2B). Extremely high cytokine and chemokineconcentrations were found for S. aureus and E. coli infections and for mice having been treated withLPS. Taken together, these data show that in all cases a systemicinfection was obtained. Although the responses did vary in magnitudewith S. aureus and E. coli havingthe highest responses, the responses for all bacteria, LPS and MALP2were elevated in a similar direction.


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)

Physiological and immunological conditionsin response to bacterialinfections and to LPS and MALP2 administration, 24 h post-infection.C57BL/6 wild-type mice were infected intraperitoneally with 1 mL of S. aureus (S.a.), S. pneumoniae (S.p.), E. coli (E.c.), and P. aeruginosa (P.a.)suspensions. Saline, LPS, and MALP2 were also ip-injected. (A) Weightloss, MPO activity from lung tissue and leukocyte counts from bothblood and peritoneal lavage. Significance of paired t tests on differences in physiological parameters between controlsand infected mice (1) p < 0.01, (2) p < 0.002, (3) p < 0.05. White blood cell countsdid not differ significantly between the control group and infectedmice. (B) Levels of cytokines and chemokines in mouse serum.
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fig2: Physiological and immunological conditionsin response to bacterialinfections and to LPS and MALP2 administration, 24 h post-infection.C57BL/6 wild-type mice were infected intraperitoneally with 1 mL of S. aureus (S.a.), S. pneumoniae (S.p.), E. coli (E.c.), and P. aeruginosa (P.a.)suspensions. Saline, LPS, and MALP2 were also ip-injected. (A) Weightloss, MPO activity from lung tissue and leukocyte counts from bothblood and peritoneal lavage. Significance of paired t tests on differences in physiological parameters between controlsand infected mice (1) p < 0.01, (2) p < 0.002, (3) p < 0.05. White blood cell countsdid not differ significantly between the control group and infectedmice. (B) Levels of cytokines and chemokines in mouse serum.
Mentions: In our study, we investigated host-microbe interactionsusing twoGram-positive and two Gram-negative organisms: S. aureus, S. pneumonia, E. coli, and P. aeruginosa. The bacterial dose was adjusted to 107 CFU/mL for S. aureus, S. pneumoniae, and E. coli and 106 CFU/mL for P. aeruginosa and resulted in a survival rate of 100% onday one post injection. Twenty-four hours post bacteria administration,mice (n = 8 for each kind of infection) showed CFUsin the lungs (results not shown) as a result of a systemic progressionof the bacterial infection. Additionally, mice were examined accordingto their health condition and status of inflammation by comparingbody weight, Myeloperoxidase (MPO) activity in the lungs, white bloodcell counts in blood and peritoneal lavage, as well as cytokine/chemokinelevels (IL-6, IL-10, G-CSF, KC, MCP-1, MIP-1a, RANTES, TNFa) in serum(Figure 2). The data were compared with shammice (ip injection of 1 mL of saline, n = 7) andanimals having obtained an intraperitoneal injection of LPS (n = 8) and MALP2 (n = 6). For LPS and MALP2,a dose of 0.5 mg/kg and 5 μg/mouse dissolved in a volume of200 μL saline was applied, respectively. Twenty-four h afterinfection, some animals showed signs of diarrhea and stopped eatingand drinking, which resulted in a higher weight loss compared to thecontrol group (Figure 2A). All infected micedeveloped to a similar extent significantly elevated leukocyte countsin the peritoneal lavage (p < 0.01) as well asincreased MPO activity (p < 0.05) in the lungsas a result of neutrophilic influx while white blood counts in blooddid not change significantly compared to the controls. In addition,animals showed enhanced serum levels of different cytokines (IL-6,IL-10, G-CSF, and TNFa) and chemokines (KC, MCP-1, MIP-1a, RANTES)demonstrating that an intense systemic inflammatory response has developed(Figure 2B). Extremely high cytokine and chemokineconcentrations were found for S. aureus and E. coli infections and for mice having been treated withLPS. Taken together, these data show that in all cases a systemicinfection was obtained. Although the responses did vary in magnitudewith S. aureus and E. coli havingthe highest responses, the responses for all bacteria, LPS and MALP2were elevated in a similar direction.

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