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Human dendritic cell DC-SIGN and TLR-2 mediate complementary immune regulatory activities in response to Lactobacillus rhamnosus JB-1.

Konieczna P, Schiavi E, Ziegler M, Groeger D, Healy S, Grant R, O'Mahony L - PLoS ONE (2015)

Bottom Line: The mechanisms underpinning these protective effects are beginning to be elucidated.Lb. murinus has no such anti-inflammatory protective effects and was used as a comparator organism.Lb. rhamnosus JB-1 adhered to MDDCs, but internalization and intracellular processing was significantly delayed, compared to Lb. murinus which was rapidly internalized and processed.

View Article: PubMed Central - PubMed

Affiliation: Swiss Institute of Allergy and Asthma Research, University of Zurich, Davos, Switzerland.

ABSTRACT
The microbiota is required for optimal host development and ongoing immune homeostasis. Lactobacilli are common inhabitants of the mammalian large intestine and immunoregulatory effects have been described for certain, but not all, strains. The mechanisms underpinning these protective effects are beginning to be elucidated. One such protective organism is Lactobacillus rhamnosus JB-1 (Lb. rhamnosus JB-1). Lb. murinus has no such anti-inflammatory protective effects and was used as a comparator organism. Human monocyte-derived dendritic cells (MDDCs) were co-incubated with bacteria and analysed over time for bacterial adhesion and intracellular processing, costimulatory molecule expression, cytokine secretion and induction of lymphocyte polarization. Neutralising antibodies were utilized to identify the responsible MDDC receptors. Lb. rhamnosus JB-1 adhered to MDDCs, but internalization and intracellular processing was significantly delayed, compared to Lb. murinus which was rapidly internalized and processed. Lb. murinus induced CD80 and CD86 expression, accompanied by high levels of cytokine secretion, while Lb. rhamnosus JB-1 was a poor inducer of costimulatory molecule expression and cytokine secretion. Lb. rhamnosus JB-1 primed MDDCs induced Foxp3 expression in autologous lymphocytes, while Lb. murinus primed MDDCs induced Foxp3, T-bet and Ror-γt expression. DC-SIGN was required for Lb. rhamnosus JB-1 adhesion and influenced IL-12 secretion, while TLR-2 influenced IL-10 and IL-12 secretion. Here we demonstrate that the delayed kinetics of bacterial processing by MDDCs correlates with MDDC activation and stimulation of lymphocytes. Thus, inhibition or delay of intracellular processing may be a novel strategy by which certain commensals may avoid the induction of proinflammatory responses.

No MeSH data available.


Related in: MedlinePlus

Lb. rhamnosus JB-1 internalisation by MDDCs.(A) Following antibiotic treatment, which kills bacteria outside MDDCs, the peak recovery of viable Lb. rhamnosus JB-1 was observed after 48 hours, suggesting that this was the time point when the bacteria were internalized by the MDDCs. (B) MDDC phagocytosis of another bacterial strain, E. coli, was reduced when the MDDCs were co-exposed to Lb. rhamnosus JB-1, but not Lb. murinus.
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pone.0120261.g002: Lb. rhamnosus JB-1 internalisation by MDDCs.(A) Following antibiotic treatment, which kills bacteria outside MDDCs, the peak recovery of viable Lb. rhamnosus JB-1 was observed after 48 hours, suggesting that this was the time point when the bacteria were internalized by the MDDCs. (B) MDDC phagocytosis of another bacterial strain, E. coli, was reduced when the MDDCs were co-exposed to Lb. rhamnosus JB-1, but not Lb. murinus.

Mentions: Human monocyte-derived dendritic cells (MDDCs) efficiently bind Lb. rhamnosus JB-1 as demonstrated by multispectral image stream analysis (Fig. 1A). In order to examine Lb. rhamnosus JB-1 internalisation and processing in more detail, we further examined MDDC responses to this microbe over an extended timeframe using confocal microscopy (Fig. 1B). Surprisingly, MDDCs did not internalize Lb. rhamnosus JB-1 for at least 48 hours following co-incubation, despite binding a large number of microbes on the cell surface. In addition, the binding pattern was unusual as distinct clustering of the bound microbe around the nucleus of the MDDCs was evident, even up to 96 hours following co-incubation. This delay in processing of Lb. rhamnosus JB-1 was not oberserved for an unrelated Lb. murinus strain (Fig. 1C), while the peri-nuclear binding was also not observed for Lb. murinus. Internalization of Lb. rhamnosus JB-1 was shown to peak at 48 hours as antibiotic treatment of the dendritic cells kills bacteria on the surface of the cells, while internalized bacteria are protected from the antibiotic allowing their growth and enumeration on agar plates (Fig. 2A). In addition, phagocytosis of fluorescently labeled E. coli was delayed in Lb. rhamnosus JB-1 treated dendritic cells, but not in Lb. murinus treated dendritic cells (Fig. 2B).


Human dendritic cell DC-SIGN and TLR-2 mediate complementary immune regulatory activities in response to Lactobacillus rhamnosus JB-1.

Konieczna P, Schiavi E, Ziegler M, Groeger D, Healy S, Grant R, O'Mahony L - PLoS ONE (2015)

Lb. rhamnosus JB-1 internalisation by MDDCs.(A) Following antibiotic treatment, which kills bacteria outside MDDCs, the peak recovery of viable Lb. rhamnosus JB-1 was observed after 48 hours, suggesting that this was the time point when the bacteria were internalized by the MDDCs. (B) MDDC phagocytosis of another bacterial strain, E. coli, was reduced when the MDDCs were co-exposed to Lb. rhamnosus JB-1, but not Lb. murinus.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376398&req=5

pone.0120261.g002: Lb. rhamnosus JB-1 internalisation by MDDCs.(A) Following antibiotic treatment, which kills bacteria outside MDDCs, the peak recovery of viable Lb. rhamnosus JB-1 was observed after 48 hours, suggesting that this was the time point when the bacteria were internalized by the MDDCs. (B) MDDC phagocytosis of another bacterial strain, E. coli, was reduced when the MDDCs were co-exposed to Lb. rhamnosus JB-1, but not Lb. murinus.
Mentions: Human monocyte-derived dendritic cells (MDDCs) efficiently bind Lb. rhamnosus JB-1 as demonstrated by multispectral image stream analysis (Fig. 1A). In order to examine Lb. rhamnosus JB-1 internalisation and processing in more detail, we further examined MDDC responses to this microbe over an extended timeframe using confocal microscopy (Fig. 1B). Surprisingly, MDDCs did not internalize Lb. rhamnosus JB-1 for at least 48 hours following co-incubation, despite binding a large number of microbes on the cell surface. In addition, the binding pattern was unusual as distinct clustering of the bound microbe around the nucleus of the MDDCs was evident, even up to 96 hours following co-incubation. This delay in processing of Lb. rhamnosus JB-1 was not oberserved for an unrelated Lb. murinus strain (Fig. 1C), while the peri-nuclear binding was also not observed for Lb. murinus. Internalization of Lb. rhamnosus JB-1 was shown to peak at 48 hours as antibiotic treatment of the dendritic cells kills bacteria on the surface of the cells, while internalized bacteria are protected from the antibiotic allowing their growth and enumeration on agar plates (Fig. 2A). In addition, phagocytosis of fluorescently labeled E. coli was delayed in Lb. rhamnosus JB-1 treated dendritic cells, but not in Lb. murinus treated dendritic cells (Fig. 2B).

Bottom Line: The mechanisms underpinning these protective effects are beginning to be elucidated.Lb. murinus has no such anti-inflammatory protective effects and was used as a comparator organism.Lb. rhamnosus JB-1 adhered to MDDCs, but internalization and intracellular processing was significantly delayed, compared to Lb. murinus which was rapidly internalized and processed.

View Article: PubMed Central - PubMed

Affiliation: Swiss Institute of Allergy and Asthma Research, University of Zurich, Davos, Switzerland.

ABSTRACT
The microbiota is required for optimal host development and ongoing immune homeostasis. Lactobacilli are common inhabitants of the mammalian large intestine and immunoregulatory effects have been described for certain, but not all, strains. The mechanisms underpinning these protective effects are beginning to be elucidated. One such protective organism is Lactobacillus rhamnosus JB-1 (Lb. rhamnosus JB-1). Lb. murinus has no such anti-inflammatory protective effects and was used as a comparator organism. Human monocyte-derived dendritic cells (MDDCs) were co-incubated with bacteria and analysed over time for bacterial adhesion and intracellular processing, costimulatory molecule expression, cytokine secretion and induction of lymphocyte polarization. Neutralising antibodies were utilized to identify the responsible MDDC receptors. Lb. rhamnosus JB-1 adhered to MDDCs, but internalization and intracellular processing was significantly delayed, compared to Lb. murinus which was rapidly internalized and processed. Lb. murinus induced CD80 and CD86 expression, accompanied by high levels of cytokine secretion, while Lb. rhamnosus JB-1 was a poor inducer of costimulatory molecule expression and cytokine secretion. Lb. rhamnosus JB-1 primed MDDCs induced Foxp3 expression in autologous lymphocytes, while Lb. murinus primed MDDCs induced Foxp3, T-bet and Ror-γt expression. DC-SIGN was required for Lb. rhamnosus JB-1 adhesion and influenced IL-12 secretion, while TLR-2 influenced IL-10 and IL-12 secretion. Here we demonstrate that the delayed kinetics of bacterial processing by MDDCs correlates with MDDC activation and stimulation of lymphocytes. Thus, inhibition or delay of intracellular processing may be a novel strategy by which certain commensals may avoid the induction of proinflammatory responses.

No MeSH data available.


Related in: MedlinePlus