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A changing gastric environment leads to adaptation of lipopolysaccharide variants in Helicobacter pylori populations during colonization.

Skoglund A, Bäckhed HK, Nilsson C, Björkholm B, Normark S, Engstrand L - PLoS ONE (2009)

Bottom Line: The majority of H. pylori isolates produce lipopolysaccharides (LPS) decorated with human-related Lewis epitopes, which have been shown to phase-vary in response to different environmental conditions.The clinical isolates from different human individuals showed that intra-individual isolates varied in Lewis antigen expression although the LPS diversity was relatively stable within each individual over time.Moreover, the isolates demonstrated considerable diversity in the levels of glycosylation and in the sizes of fucosylated O-antigen chains both within and between individuals.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden.

ABSTRACT
The human gastric pathogen Helicobacter pylori colonizes the stomachs of half of the human population, and causes development of peptic ulcer disease and gastric adenocarcinoma. H. pylori-associated chronic atrophic gastritis (ChAG) with loss of the acid-producing parietal cells, is correlated with an increased risk for development of gastric adenocarcinoma. The majority of H. pylori isolates produce lipopolysaccharides (LPS) decorated with human-related Lewis epitopes, which have been shown to phase-vary in response to different environmental conditions. We have characterized the adaptations of H. pylori LPS and Lewis antigen expression to varying gastric conditions; in H. pylori isolates from mice with low or high gastric pH, respectively; in 482 clinical isolates from healthy individuals and from individuals with ChAG obtained at two time points with a four-year interval between endoscopies; and finally in isolates grown at different pH in vitro. Here we show that the gastric environment can contribute to a switch in Lewis phenotype in the two experimental mouse models. The clinical isolates from different human individuals showed that intra-individual isolates varied in Lewis antigen expression although the LPS diversity was relatively stable within each individual over time. Moreover, the isolates demonstrated considerable diversity in the levels of glycosylation and in the sizes of fucosylated O-antigen chains both within and between individuals. Thus our data suggest that different LPS variants exist in the colonizing H. pylori population, which can adapt to changes in the gastric environment and provide a means to regulate the inflammatory response of the host during disease progression.

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Lewis antigen expression in clinical H. pylori isolates shows large intra-individual diversity.Western blots detecting Lex and Ley antigens. Fifteen single-colony isolates were analyzed from each individual and time point. (A) High variability of Lewis antigen pattern was usually observed among intra-individual isolates, e.g. in single-colony isolates from Kx345 where large variation in sizes of Lex and Ley fucosylated O-antigen chains were detected. Here all the four different Lewis antigen phenotypes are represented: those expressing both Lex and Ley, isolates that only expressed Lex or Ley and strains that lacked expression of both these Lewis antigens. (B) Kx438 isolates simultaneously expressed both Lex and Ley at both time points, except two isolates at year 0 (isolate 3 and 9) that only expressed Ley, but with comparably higher intensities. (C) The Kx1379 isolates show how the amount of Lewis antigen expression can vary in expression intensities, e.g. at year 4, where low amounts of Ley were expressed in isolates 2, 3, 4, 5 and 7 as compared to isolates 1, 6 and 8–15, where more pronounced Ley expression was observed.
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pone-0005885-g003: Lewis antigen expression in clinical H. pylori isolates shows large intra-individual diversity.Western blots detecting Lex and Ley antigens. Fifteen single-colony isolates were analyzed from each individual and time point. (A) High variability of Lewis antigen pattern was usually observed among intra-individual isolates, e.g. in single-colony isolates from Kx345 where large variation in sizes of Lex and Ley fucosylated O-antigen chains were detected. Here all the four different Lewis antigen phenotypes are represented: those expressing both Lex and Ley, isolates that only expressed Lex or Ley and strains that lacked expression of both these Lewis antigens. (B) Kx438 isolates simultaneously expressed both Lex and Ley at both time points, except two isolates at year 0 (isolate 3 and 9) that only expressed Ley, but with comparably higher intensities. (C) The Kx1379 isolates show how the amount of Lewis antigen expression can vary in expression intensities, e.g. at year 4, where low amounts of Ley were expressed in isolates 2, 3, 4, 5 and 7 as compared to isolates 1, 6 and 8–15, where more pronounced Ley expression was observed.

Mentions: To assess the variability of LPS phenotypes within an individual's H. pylori population, we compared banding patterns on the immunoblots, which represent diverse sizes of O-antigen chains that are Lex- and/or Ley-glycosylated. Fifteen single-colony isolates from 17 individuals were examined, of which three representative examples are given in Figure 3, and the remaining isolates in Figure S1. We were able to identify intra-strain diversity of Lewis epitopes in the same microenvironment, i.e. the 15 single-colony isolates from the same biopsy presented diverse Lewis antigen profiles with immunoblotting (Figures 3A-C and Figure S1). Both expression levels, pattern of Lewis glycosylation and the sizes of O-antigen chains that were fucosylated, varied in isolates obtained from the same individual. This indicates an advantage of maintaining a high phenotypic diversity of the LPS molecule within the bacterial community. Often, Lex-glycosylated O-antigen chains were restricted to only a few sizes, while the Ley antigen was present on O-antigen chains of several sizes. This phenomenon was observed in isolates from both normal and atrophic individuals, and typically when occurring, found at both time points. Thus the diversification seemed to be sustained within isolates from the same individual. However, no correlation in expression intensity was found over time or in association with disease development.


A changing gastric environment leads to adaptation of lipopolysaccharide variants in Helicobacter pylori populations during colonization.

Skoglund A, Bäckhed HK, Nilsson C, Björkholm B, Normark S, Engstrand L - PLoS ONE (2009)

Lewis antigen expression in clinical H. pylori isolates shows large intra-individual diversity.Western blots detecting Lex and Ley antigens. Fifteen single-colony isolates were analyzed from each individual and time point. (A) High variability of Lewis antigen pattern was usually observed among intra-individual isolates, e.g. in single-colony isolates from Kx345 where large variation in sizes of Lex and Ley fucosylated O-antigen chains were detected. Here all the four different Lewis antigen phenotypes are represented: those expressing both Lex and Ley, isolates that only expressed Lex or Ley and strains that lacked expression of both these Lewis antigens. (B) Kx438 isolates simultaneously expressed both Lex and Ley at both time points, except two isolates at year 0 (isolate 3 and 9) that only expressed Ley, but with comparably higher intensities. (C) The Kx1379 isolates show how the amount of Lewis antigen expression can vary in expression intensities, e.g. at year 4, where low amounts of Ley were expressed in isolates 2, 3, 4, 5 and 7 as compared to isolates 1, 6 and 8–15, where more pronounced Ley expression was observed.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2690825&req=5

pone-0005885-g003: Lewis antigen expression in clinical H. pylori isolates shows large intra-individual diversity.Western blots detecting Lex and Ley antigens. Fifteen single-colony isolates were analyzed from each individual and time point. (A) High variability of Lewis antigen pattern was usually observed among intra-individual isolates, e.g. in single-colony isolates from Kx345 where large variation in sizes of Lex and Ley fucosylated O-antigen chains were detected. Here all the four different Lewis antigen phenotypes are represented: those expressing both Lex and Ley, isolates that only expressed Lex or Ley and strains that lacked expression of both these Lewis antigens. (B) Kx438 isolates simultaneously expressed both Lex and Ley at both time points, except two isolates at year 0 (isolate 3 and 9) that only expressed Ley, but with comparably higher intensities. (C) The Kx1379 isolates show how the amount of Lewis antigen expression can vary in expression intensities, e.g. at year 4, where low amounts of Ley were expressed in isolates 2, 3, 4, 5 and 7 as compared to isolates 1, 6 and 8–15, where more pronounced Ley expression was observed.
Mentions: To assess the variability of LPS phenotypes within an individual's H. pylori population, we compared banding patterns on the immunoblots, which represent diverse sizes of O-antigen chains that are Lex- and/or Ley-glycosylated. Fifteen single-colony isolates from 17 individuals were examined, of which three representative examples are given in Figure 3, and the remaining isolates in Figure S1. We were able to identify intra-strain diversity of Lewis epitopes in the same microenvironment, i.e. the 15 single-colony isolates from the same biopsy presented diverse Lewis antigen profiles with immunoblotting (Figures 3A-C and Figure S1). Both expression levels, pattern of Lewis glycosylation and the sizes of O-antigen chains that were fucosylated, varied in isolates obtained from the same individual. This indicates an advantage of maintaining a high phenotypic diversity of the LPS molecule within the bacterial community. Often, Lex-glycosylated O-antigen chains were restricted to only a few sizes, while the Ley antigen was present on O-antigen chains of several sizes. This phenomenon was observed in isolates from both normal and atrophic individuals, and typically when occurring, found at both time points. Thus the diversification seemed to be sustained within isolates from the same individual. However, no correlation in expression intensity was found over time or in association with disease development.

Bottom Line: The majority of H. pylori isolates produce lipopolysaccharides (LPS) decorated with human-related Lewis epitopes, which have been shown to phase-vary in response to different environmental conditions.The clinical isolates from different human individuals showed that intra-individual isolates varied in Lewis antigen expression although the LPS diversity was relatively stable within each individual over time.Moreover, the isolates demonstrated considerable diversity in the levels of glycosylation and in the sizes of fucosylated O-antigen chains both within and between individuals.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden.

ABSTRACT
The human gastric pathogen Helicobacter pylori colonizes the stomachs of half of the human population, and causes development of peptic ulcer disease and gastric adenocarcinoma. H. pylori-associated chronic atrophic gastritis (ChAG) with loss of the acid-producing parietal cells, is correlated with an increased risk for development of gastric adenocarcinoma. The majority of H. pylori isolates produce lipopolysaccharides (LPS) decorated with human-related Lewis epitopes, which have been shown to phase-vary in response to different environmental conditions. We have characterized the adaptations of H. pylori LPS and Lewis antigen expression to varying gastric conditions; in H. pylori isolates from mice with low or high gastric pH, respectively; in 482 clinical isolates from healthy individuals and from individuals with ChAG obtained at two time points with a four-year interval between endoscopies; and finally in isolates grown at different pH in vitro. Here we show that the gastric environment can contribute to a switch in Lewis phenotype in the two experimental mouse models. The clinical isolates from different human individuals showed that intra-individual isolates varied in Lewis antigen expression although the LPS diversity was relatively stable within each individual over time. Moreover, the isolates demonstrated considerable diversity in the levels of glycosylation and in the sizes of fucosylated O-antigen chains both within and between individuals. Thus our data suggest that different LPS variants exist in the colonizing H. pylori population, which can adapt to changes in the gastric environment and provide a means to regulate the inflammatory response of the host during disease progression.

Show MeSH
Related in: MedlinePlus