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The intestinal microbiota plays a role in Salmonella-induced colitis independent of pathogen colonization.

Ferreira RB, Gill N, Willing BP, Antunes LC, Russell SL, Croxen MA, Finlay BB - PLoS ONE (2011)

Bottom Line: Although all antibiotic treatments caused similar increases in pathogen colonization, the development of enterocolitis was seen only when streptomycin or vancomycin was used; no significant pathology was observed with the use of metronidazole.Our data suggests that different members of the microbiota might be associated with S.Dissecting the mechanisms involved in resistance to infection and inflammation will be critical for the development of therapeutic and preventative measures against enteric pathogens.

View Article: PubMed Central - PubMed

Affiliation: Michael Smith Laboratories, The University of British Columbia, Vancouver, British Columbia, Canada.

ABSTRACT
The intestinal microbiota is composed of hundreds of species of bacteria, fungi and protozoa and is critical for numerous biological processes, such as nutrient acquisition, vitamin production, and colonization resistance against bacterial pathogens. We studied the role of the intestinal microbiota on host resistance to Salmonella enterica serovar Typhimurium-induced colitis. Using multiple antibiotic treatments in 129S1/SvImJ mice, we showed that disruption of the intestinal microbiota alters host susceptibility to infection. Although all antibiotic treatments caused similar increases in pathogen colonization, the development of enterocolitis was seen only when streptomycin or vancomycin was used; no significant pathology was observed with the use of metronidazole. Interestingly, metronidazole-treated and infected C57BL/6 mice developed severe pathology. We hypothesized that the intestinal microbiota confers resistance to infectious colitis without affecting the ability of S. Typhimurium to colonize the intestine. Indeed, different antibiotic treatments caused distinct shifts in the intestinal microbiota prior to infection. Through fluorescence in situ hybridization, terminal restriction fragment length polymorphism, and real-time PCR, we showed that there is a strong correlation between the intestinal microbiota composition before infection and susceptibility to Salmonella-induced colitis. Members of the Bacteroidetes phylum were present at significantly higher levels in mice resistant to colitis. Further analysis revealed that Porphyromonadaceae levels were also increased in these mice. Conversely, there was a positive correlation between the abundance of Lactobacillus sp. and predisposition to colitis. Our data suggests that different members of the microbiota might be associated with S. Typhimurium colonization and colitis. Dissecting the mechanisms involved in resistance to infection and inflammation will be critical for the development of therapeutic and preventative measures against enteric pathogens.

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Specific members of the microbiota are involved in predisposition to                            colitis.The contribution of individual peaks to the total peak intensity of each                            sample was determined through TRFLP analyses. A. Porphyromonadaceae (TFR                            83–87). B. Lachnospiraceae (TRF 154). C.                                Lactobacillus sp. (TRF 187–188).                                ns: not significant; *: p<0.05; **:                            p<0.01; ***: p≤0.001. Experiments were performed three                            times with at least 4 mice in each group.
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pone-0020338-g004: Specific members of the microbiota are involved in predisposition to colitis.The contribution of individual peaks to the total peak intensity of each sample was determined through TRFLP analyses. A. Porphyromonadaceae (TFR 83–87). B. Lachnospiraceae (TRF 154). C. Lactobacillus sp. (TRF 187–188). ns: not significant; *: p<0.05; **: p<0.01; ***: p≤0.001. Experiments were performed three times with at least 4 mice in each group.

Mentions: By comparing the abundance of individual terminal restriction fragment (TRF) lengths in protective versus non-protective conditions it was possible to identify a small subset of TRFs that were negatively and positively correlated with susceptibility to colitis. Clone libraries of 16S rRNA genes were generated and screened with restriction digestion to allow for phylogenetic assignment of TRFs of interest. TRFs in the range of 83 to 87 bp remained abundant after metronidazole treatment of 129S1/SvImJ mice, but were significantly decreased in colitis-susceptible mice, thus representing potentially protective organisms (Figure 4A). Clones corresponding to these TRFs were all classified within the family Porphyromonadaceae from the Bacteroidetes phylum. Conversely, TRF188, identified as Lactobacillus, was present at increased levels in streptomycin-treated 129S1/SvImJ and metronidazole-treated C57BL/6, but was not detectable after metronidazole treatment of 129S1/SvImJ, and was thus positively correlated with colitis susceptibility (Figure 4C). We also found that TRF154 was present at significantly higher levels in metronizadole-treated 129S1/SvImJ, but was unaffected by other treatments (Figure 4B). Clones corresponding to this TRF were classified within the family Lachnospiraceae. It is important to note that an attempt to grow viable bacteria from the fecal microbiota of the different groups in selective media showed no correlation with the phenotypes observed in mice (data not shown). This highlights the importance of DNA-based methodologies to thoroughly analyze the composition of the intestinal microbiota.


The intestinal microbiota plays a role in Salmonella-induced colitis independent of pathogen colonization.

Ferreira RB, Gill N, Willing BP, Antunes LC, Russell SL, Croxen MA, Finlay BB - PLoS ONE (2011)

Specific members of the microbiota are involved in predisposition to                            colitis.The contribution of individual peaks to the total peak intensity of each                            sample was determined through TRFLP analyses. A. Porphyromonadaceae (TFR                            83–87). B. Lachnospiraceae (TRF 154). C.                                Lactobacillus sp. (TRF 187–188).                                ns: not significant; *: p<0.05; **:                            p<0.01; ***: p≤0.001. Experiments were performed three                            times with at least 4 mice in each group.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3102097&req=5

pone-0020338-g004: Specific members of the microbiota are involved in predisposition to colitis.The contribution of individual peaks to the total peak intensity of each sample was determined through TRFLP analyses. A. Porphyromonadaceae (TFR 83–87). B. Lachnospiraceae (TRF 154). C. Lactobacillus sp. (TRF 187–188). ns: not significant; *: p<0.05; **: p<0.01; ***: p≤0.001. Experiments were performed three times with at least 4 mice in each group.
Mentions: By comparing the abundance of individual terminal restriction fragment (TRF) lengths in protective versus non-protective conditions it was possible to identify a small subset of TRFs that were negatively and positively correlated with susceptibility to colitis. Clone libraries of 16S rRNA genes were generated and screened with restriction digestion to allow for phylogenetic assignment of TRFs of interest. TRFs in the range of 83 to 87 bp remained abundant after metronidazole treatment of 129S1/SvImJ mice, but were significantly decreased in colitis-susceptible mice, thus representing potentially protective organisms (Figure 4A). Clones corresponding to these TRFs were all classified within the family Porphyromonadaceae from the Bacteroidetes phylum. Conversely, TRF188, identified as Lactobacillus, was present at increased levels in streptomycin-treated 129S1/SvImJ and metronidazole-treated C57BL/6, but was not detectable after metronidazole treatment of 129S1/SvImJ, and was thus positively correlated with colitis susceptibility (Figure 4C). We also found that TRF154 was present at significantly higher levels in metronizadole-treated 129S1/SvImJ, but was unaffected by other treatments (Figure 4B). Clones corresponding to this TRF were classified within the family Lachnospiraceae. It is important to note that an attempt to grow viable bacteria from the fecal microbiota of the different groups in selective media showed no correlation with the phenotypes observed in mice (data not shown). This highlights the importance of DNA-based methodologies to thoroughly analyze the composition of the intestinal microbiota.

Bottom Line: Although all antibiotic treatments caused similar increases in pathogen colonization, the development of enterocolitis was seen only when streptomycin or vancomycin was used; no significant pathology was observed with the use of metronidazole.Our data suggests that different members of the microbiota might be associated with S.Dissecting the mechanisms involved in resistance to infection and inflammation will be critical for the development of therapeutic and preventative measures against enteric pathogens.

View Article: PubMed Central - PubMed

Affiliation: Michael Smith Laboratories, The University of British Columbia, Vancouver, British Columbia, Canada.

ABSTRACT
The intestinal microbiota is composed of hundreds of species of bacteria, fungi and protozoa and is critical for numerous biological processes, such as nutrient acquisition, vitamin production, and colonization resistance against bacterial pathogens. We studied the role of the intestinal microbiota on host resistance to Salmonella enterica serovar Typhimurium-induced colitis. Using multiple antibiotic treatments in 129S1/SvImJ mice, we showed that disruption of the intestinal microbiota alters host susceptibility to infection. Although all antibiotic treatments caused similar increases in pathogen colonization, the development of enterocolitis was seen only when streptomycin or vancomycin was used; no significant pathology was observed with the use of metronidazole. Interestingly, metronidazole-treated and infected C57BL/6 mice developed severe pathology. We hypothesized that the intestinal microbiota confers resistance to infectious colitis without affecting the ability of S. Typhimurium to colonize the intestine. Indeed, different antibiotic treatments caused distinct shifts in the intestinal microbiota prior to infection. Through fluorescence in situ hybridization, terminal restriction fragment length polymorphism, and real-time PCR, we showed that there is a strong correlation between the intestinal microbiota composition before infection and susceptibility to Salmonella-induced colitis. Members of the Bacteroidetes phylum were present at significantly higher levels in mice resistant to colitis. Further analysis revealed that Porphyromonadaceae levels were also increased in these mice. Conversely, there was a positive correlation between the abundance of Lactobacillus sp. and predisposition to colitis. Our data suggests that different members of the microbiota might be associated with S. Typhimurium colonization and colitis. Dissecting the mechanisms involved in resistance to infection and inflammation will be critical for the development of therapeutic and preventative measures against enteric pathogens.

Show MeSH
Related in: MedlinePlus