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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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Comparisonof intravenous (iv), intraperitoneal (ip), and subcutaneous(sc) administration of S. aureus. (A) S.aureus Xen29 possessing a stable copy of the luxABCDE operonwas imaged to study the redistribution of bacteria after ip and scinjection. Images obtained after 4 and 24 h are shown. While thereappears to be little redistribution from the initial injection siteafter sc injection, good redistribution is observed following ip injection.(B) PCA analysis (three components, R2 = 0.48, Q2 = 0.25) of serumof S. aureus infected mice and controls. The analysisshows that the three routes of administration (sc, ip, iv) give comparableresults when compared against control mice and mice injected withsaline. In particular, ip and sc administration show good agreementwith each other. Nontreated mice and saline injected mice behavedin a very similar manner.
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fig1: Comparisonof intravenous (iv), intraperitoneal (ip), and subcutaneous(sc) administration of S. aureus. (A) S.aureus Xen29 possessing a stable copy of the luxABCDE operonwas imaged to study the redistribution of bacteria after ip and scinjection. Images obtained after 4 and 24 h are shown. While thereappears to be little redistribution from the initial injection siteafter sc injection, good redistribution is observed following ip injection.(B) PCA analysis (three components, R2 = 0.48, Q2 = 0.25) of serumof S. aureus infected mice and controls. The analysisshows that the three routes of administration (sc, ip, iv) give comparableresults when compared against control mice and mice injected withsaline. In particular, ip and sc administration show good agreementwith each other. Nontreated mice and saline injected mice behavedin a very similar manner.

Mentions: To establish a reliable mouse model, S. aureus infections were induced with the bioluminescence Xen29 strain inwild-type C57BL/6 mice by intraperitoneal (ip, 1 × 107 CFUs), intravenous (iv, 1 × 107 CFUs), and subcutaneous(sc, 1 × 108 CFUs) administration. Their progressionwas monitored by bioluminescence as well as by NMR-based metabolomics.Over the course of 24 h, the intensity of the bioluminescence changedsignificantly when following the concentration of detectable pathogenslocated closely to the skin surface (Figure 1A). The fast systemic distribution of bacteria after intraperitonealinvasion led to a loss in intensity after 24 h compared to 4 h, whilefor the subcutaneous injection both an increase in bacterial densityas well as an expanded infected skin area developed. Because of immediatedispersion in blood after intravenous administration, much of thebacteria was rapidly cleared and no bioluminescence signal could bedetected in these mice after 4 or 24 h. After bioluminescence monitoring,serum was collected by cardiac puncture, and 43 metabolites were identifiedand quantified by 1H NMR and compared with those detectedin controls (untreated, n = 14; sham infected with1 mL of saline ip injected, n = 7) using multivariatestatistical pattern recognition techniques. Principle component analysis(PCA; three components, R2 = 0.48, Q2 = 0.25) scores plots revealedcomplete class distinction in the second component between infectedand healthy subjects (Figure 1B). No separationwas observed between untreated animals and those having received anip injection of 1 mL saline. However in the group of the infectedsubjects, serum samples of infected mice having the same site of infectiongrouped together in the first component according to the similaritiesin their metabolomic profiles. Additionally, CFU counts in lung tissueconfirmed reliable systemic progression of the infection for boththe intraperitoneal and intravenous routes of administration. Sinceip invasion of bacteria is one of the more clinically relevant routesof infection leading to life threatening septicemic conditions inpatients, the ip infection model was utilized for all further investigations.


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)

Comparisonof intravenous (iv), intraperitoneal (ip), and subcutaneous(sc) administration of S. aureus. (A) S.aureus Xen29 possessing a stable copy of the luxABCDE operonwas imaged to study the redistribution of bacteria after ip and scinjection. Images obtained after 4 and 24 h are shown. While thereappears to be little redistribution from the initial injection siteafter sc injection, good redistribution is observed following ip injection.(B) PCA analysis (three components, R2 = 0.48, Q2 = 0.25) of serumof S. aureus infected mice and controls. The analysisshows that the three routes of administration (sc, ip, iv) give comparableresults when compared against control mice and mice injected withsaline. In particular, ip and sc administration show good agreementwith each other. Nontreated mice and saline injected mice behavedin a very similar manner.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1: Comparisonof intravenous (iv), intraperitoneal (ip), and subcutaneous(sc) administration of S. aureus. (A) S.aureus Xen29 possessing a stable copy of the luxABCDE operonwas imaged to study the redistribution of bacteria after ip and scinjection. Images obtained after 4 and 24 h are shown. While thereappears to be little redistribution from the initial injection siteafter sc injection, good redistribution is observed following ip injection.(B) PCA analysis (three components, R2 = 0.48, Q2 = 0.25) of serumof S. aureus infected mice and controls. The analysisshows that the three routes of administration (sc, ip, iv) give comparableresults when compared against control mice and mice injected withsaline. In particular, ip and sc administration show good agreementwith each other. Nontreated mice and saline injected mice behavedin a very similar manner.
Mentions: To establish a reliable mouse model, S. aureus infections were induced with the bioluminescence Xen29 strain inwild-type C57BL/6 mice by intraperitoneal (ip, 1 × 107 CFUs), intravenous (iv, 1 × 107 CFUs), and subcutaneous(sc, 1 × 108 CFUs) administration. Their progressionwas monitored by bioluminescence as well as by NMR-based metabolomics.Over the course of 24 h, the intensity of the bioluminescence changedsignificantly when following the concentration of detectable pathogenslocated closely to the skin surface (Figure 1A). The fast systemic distribution of bacteria after intraperitonealinvasion led to a loss in intensity after 24 h compared to 4 h, whilefor the subcutaneous injection both an increase in bacterial densityas well as an expanded infected skin area developed. Because of immediatedispersion in blood after intravenous administration, much of thebacteria was rapidly cleared and no bioluminescence signal could bedetected in these mice after 4 or 24 h. After bioluminescence monitoring,serum was collected by cardiac puncture, and 43 metabolites were identifiedand quantified by 1H NMR and compared with those detectedin controls (untreated, n = 14; sham infected with1 mL of saline ip injected, n = 7) using multivariatestatistical pattern recognition techniques. Principle component analysis(PCA; three components, R2 = 0.48, Q2 = 0.25) scores plots revealedcomplete class distinction in the second component between infectedand healthy subjects (Figure 1B). No separationwas observed between untreated animals and those having received anip injection of 1 mL saline. However in the group of the infectedsubjects, serum samples of infected mice having the same site of infectiongrouped together in the first component according to the similaritiesin their metabolomic profiles. Additionally, CFU counts in lung tissueconfirmed reliable systemic progression of the infection for boththe intraperitoneal and intravenous routes of administration. Sinceip invasion of bacteria is one of the more clinically relevant routesof infection leading to life threatening septicemic conditions inpatients, the ip infection model was utilized for all further investigations.

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