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Commensal bacteria and expression of two major intestinal chemokines, TECK/CCL25 and MEC/CCL28, and their receptors.

Meurens F, Berri M, Siggers RH, Willing BP, Salmon H, Van Kessel AG, Gerdts V - PLoS ONE (2007)

Bottom Line: As evidenced by early comparisons of germ-free and conventional animals, the intestinal bacterial microflora has a marked effect on host intestinal immune functions.Moreover, as evidenced by in vitro experiments using two different cell lines, the pattern of regulation of CCL25 and CCL28 expression in the gut appears complex and suggests an additional role for in vivo factors.Taken together, the results highlight the key role of bacterial microflora in the development of a functional intestinal immune system in an elegant and relevant model for human immune system development.

View Article: PubMed Central - PubMed

Affiliation: Lymphocyte et Immunité des Muqueuses, UR 1282, Infectiologie Animale et Santé Publique, Institut National de la Recherche Agronomique, Nouzilly, France. meurens@tours.inra.fr

ABSTRACT

Background: CCL25/TECK and CCL28/MEC are CC chemokines primarily expressed in thymic dendritic cells and mucosal epithelial cells. Their receptors, CCR9 and CCR10, are mainly expressed on T and B lymphocytes. In human, mouse, pig and sheep CCL25 and CCL28 play an important role in the segregation and the compartmentalization of the mucosal immune system. As evidenced by early comparisons of germ-free and conventional animals, the intestinal bacterial microflora has a marked effect on host intestinal immune functions. However, little is known about the impact of bacterial colonization on constitutive and induced chemokine expressions as well as on the generation of anti-inflammatory mechanisms.

Methodology/principal findings: Therefore, we decided to focus by qPCR on the mRNA expression of two main gut chemokines, CCL25 and CCL28, their receptors CCR9 and CCR10, the Tregs marker Foxp3 and anti-inflammatory cytokines TGF-beta and IL-10 following colonization with different bacterial species within the small intestine. To accomplish this we used an original germ-free neonatal pig model and monoassociated pigs with a representative Gram-negative (Escherichia coli) or Gram-positive (Lactobacillus fermentum) commensal bacteria commonly isolated from the neonatal pig intestine. Our results show a consistent and marked effect of microbial colonization on the mRNA expression of intestinal chemokines, chemokine receptors, Foxp3 and TGF-beta. Moreover, as evidenced by in vitro experiments using two different cell lines, the pattern of regulation of CCL25 and CCL28 expression in the gut appears complex and suggests an additional role for in vivo factors.

Conclusions/significance: Taken together, the results highlight the key role of bacterial microflora in the development of a functional intestinal immune system in an elegant and relevant model for human immune system development.

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Related in: MedlinePlus

Expression of CCR9 mRNA in segments collected at 5–95% (pyloric sphincter = 5%; ileo-cecal junction = 95%) of SI length in gnotobiotic and conventional pigs derived by caesarean section and reared in isolators until 13 days of age.cDNA was synthesized from 50 ng of RNA and subjected to qPCR using primer/probe sets for CCR9. Levels of expression are expressed in copy number. Copy numbers and median from four animals are shown in each group (GF: germ free; LF: Lactobacillus fermentum; EC: Escherichia coli; CV: conventionalized with fresh adult porcine fecal material). *, P<0.05, **, P<0.01 (Student's t test and Wilcoxon Signed Rank Test (Exact)).
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pone-0000677-g003: Expression of CCR9 mRNA in segments collected at 5–95% (pyloric sphincter = 5%; ileo-cecal junction = 95%) of SI length in gnotobiotic and conventional pigs derived by caesarean section and reared in isolators until 13 days of age.cDNA was synthesized from 50 ng of RNA and subjected to qPCR using primer/probe sets for CCR9. Levels of expression are expressed in copy number. Copy numbers and median from four animals are shown in each group (GF: germ free; LF: Lactobacillus fermentum; EC: Escherichia coli; CV: conventionalized with fresh adult porcine fecal material). *, P<0.05, **, P<0.01 (Student's t test and Wilcoxon Signed Rank Test (Exact)).

Mentions: CCR9 mRNA pattern of expression was very similar to what we observed for CCL25 (Fig. 3). Indeed, the highest levels of expression for this receptor were observed in the EC group. Levels of expression of CCR9 mRNA were significantly higher in the EC than in the LF groups at 5, 50, 75 and 95% SI locations (P<0.05 at 5 and 95% SI locations and <0.01 at 50 and 75% SI locations). Furthermore, at 5, 50 and 95% SI locations, CCR9 mRNA was significantly more expressed in the EC than in the GF groups (P<0.05 except at 50% SI location where it was <0.01) (Fig. 3). As observed in the EC group, we detected higher CCR9 mRNA levels of expression in the CV than in the LF groups at 75 and 95% SI locations (P<0.05).


Commensal bacteria and expression of two major intestinal chemokines, TECK/CCL25 and MEC/CCL28, and their receptors.

Meurens F, Berri M, Siggers RH, Willing BP, Salmon H, Van Kessel AG, Gerdts V - PLoS ONE (2007)

Expression of CCR9 mRNA in segments collected at 5–95% (pyloric sphincter = 5%; ileo-cecal junction = 95%) of SI length in gnotobiotic and conventional pigs derived by caesarean section and reared in isolators until 13 days of age.cDNA was synthesized from 50 ng of RNA and subjected to qPCR using primer/probe sets for CCR9. Levels of expression are expressed in copy number. Copy numbers and median from four animals are shown in each group (GF: germ free; LF: Lactobacillus fermentum; EC: Escherichia coli; CV: conventionalized with fresh adult porcine fecal material). *, P<0.05, **, P<0.01 (Student's t test and Wilcoxon Signed Rank Test (Exact)).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1919421&req=5

pone-0000677-g003: Expression of CCR9 mRNA in segments collected at 5–95% (pyloric sphincter = 5%; ileo-cecal junction = 95%) of SI length in gnotobiotic and conventional pigs derived by caesarean section and reared in isolators until 13 days of age.cDNA was synthesized from 50 ng of RNA and subjected to qPCR using primer/probe sets for CCR9. Levels of expression are expressed in copy number. Copy numbers and median from four animals are shown in each group (GF: germ free; LF: Lactobacillus fermentum; EC: Escherichia coli; CV: conventionalized with fresh adult porcine fecal material). *, P<0.05, **, P<0.01 (Student's t test and Wilcoxon Signed Rank Test (Exact)).
Mentions: CCR9 mRNA pattern of expression was very similar to what we observed for CCL25 (Fig. 3). Indeed, the highest levels of expression for this receptor were observed in the EC group. Levels of expression of CCR9 mRNA were significantly higher in the EC than in the LF groups at 5, 50, 75 and 95% SI locations (P<0.05 at 5 and 95% SI locations and <0.01 at 50 and 75% SI locations). Furthermore, at 5, 50 and 95% SI locations, CCR9 mRNA was significantly more expressed in the EC than in the GF groups (P<0.05 except at 50% SI location where it was <0.01) (Fig. 3). As observed in the EC group, we detected higher CCR9 mRNA levels of expression in the CV than in the LF groups at 75 and 95% SI locations (P<0.05).

Bottom Line: As evidenced by early comparisons of germ-free and conventional animals, the intestinal bacterial microflora has a marked effect on host intestinal immune functions.Moreover, as evidenced by in vitro experiments using two different cell lines, the pattern of regulation of CCL25 and CCL28 expression in the gut appears complex and suggests an additional role for in vivo factors.Taken together, the results highlight the key role of bacterial microflora in the development of a functional intestinal immune system in an elegant and relevant model for human immune system development.

View Article: PubMed Central - PubMed

Affiliation: Lymphocyte et Immunité des Muqueuses, UR 1282, Infectiologie Animale et Santé Publique, Institut National de la Recherche Agronomique, Nouzilly, France. meurens@tours.inra.fr

ABSTRACT

Background: CCL25/TECK and CCL28/MEC are CC chemokines primarily expressed in thymic dendritic cells and mucosal epithelial cells. Their receptors, CCR9 and CCR10, are mainly expressed on T and B lymphocytes. In human, mouse, pig and sheep CCL25 and CCL28 play an important role in the segregation and the compartmentalization of the mucosal immune system. As evidenced by early comparisons of germ-free and conventional animals, the intestinal bacterial microflora has a marked effect on host intestinal immune functions. However, little is known about the impact of bacterial colonization on constitutive and induced chemokine expressions as well as on the generation of anti-inflammatory mechanisms.

Methodology/principal findings: Therefore, we decided to focus by qPCR on the mRNA expression of two main gut chemokines, CCL25 and CCL28, their receptors CCR9 and CCR10, the Tregs marker Foxp3 and anti-inflammatory cytokines TGF-beta and IL-10 following colonization with different bacterial species within the small intestine. To accomplish this we used an original germ-free neonatal pig model and monoassociated pigs with a representative Gram-negative (Escherichia coli) or Gram-positive (Lactobacillus fermentum) commensal bacteria commonly isolated from the neonatal pig intestine. Our results show a consistent and marked effect of microbial colonization on the mRNA expression of intestinal chemokines, chemokine receptors, Foxp3 and TGF-beta. Moreover, as evidenced by in vitro experiments using two different cell lines, the pattern of regulation of CCL25 and CCL28 expression in the gut appears complex and suggests an additional role for in vivo factors.

Conclusions/significance: Taken together, the results highlight the key role of bacterial microflora in the development of a functional intestinal immune system in an elegant and relevant model for human immune system development.

Show MeSH
Related in: MedlinePlus