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Nod2 suppresses Borrelia burgdorferi mediated murine Lyme arthritis and carditis through the induction of tolerance.

Petnicki-Ocwieja T, DeFrancesco AS, Chung E, Darcy CT, Bronson RT, Kobayashi KS, Hu LT - PLoS ONE (2011)

Bottom Line: The internalization of Borrelia burgdorferi, the causative agent of Lyme disease, by phagocytes is essential for an effective activation of the immune response to this pathogen.In vitro stimulation of Nod2 deficient bone marrow derived macrophages (BMDM) resulted in decreased induction of multiple cytokines, interferons and interferon regulated genes compared with wild-type cells.However, B. burgdorferi infection of Nod2 deficient mice resulted in increased rather than decreased arthritis and carditis compared to control mice.

View Article: PubMed Central - PubMed

Affiliation: Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Boston, Massachusetts, United States of America.

ABSTRACT
The internalization of Borrelia burgdorferi, the causative agent of Lyme disease, by phagocytes is essential for an effective activation of the immune response to this pathogen. The intracellular, cytosolic receptor Nod2 has been shown to play varying roles in either enhancing or attenuating inflammation in response to different infectious agents. We examined the role of Nod2 in responses to B. burgdorferi. In vitro stimulation of Nod2 deficient bone marrow derived macrophages (BMDM) resulted in decreased induction of multiple cytokines, interferons and interferon regulated genes compared with wild-type cells. However, B. burgdorferi infection of Nod2 deficient mice resulted in increased rather than decreased arthritis and carditis compared to control mice. We explored multiple potential mechanisms for the paradoxical response in in vivo versus in vitro systems and found that prolonged stimulation with a Nod2 ligand, muramyl dipeptide (MDP), resulted in tolerance to stimulation by B. burgdorferi. This tolerance was lost with stimulation of Nod2 deficient cells that cannot respond to MDP. Cytokine patterns in the tolerance model closely paralleled cytokine profiles in infected Nod2 deficient mice. We propose a model where Nod2 has an enhancing role in activating inflammation in early infection, but moderates inflammation after prolonged exposure to the organism through induction of tolerance.

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TLR2 independent intracellular signaling plays a role in the host response to B. burgdorferi signaling.BMDM from wild type and TLR2 deficient mice were stimulated with B. burgdorferi (MOI 10) for 6 hours and supernatants were collected. Concanamycin A (100 ng/ml) was added 30 minutes prior to stimulation. Cytokine levels in supernatants were measured by ELISA. Bars represent mean percent change in protein levels ± s.e.m. of three independent experiments. Wild type cells secreted a mean of 3.51 ng/ml, TLR2 deficient cells a mean of 1.65 ng/ml, and TLR2 deficient concanamycin treated cells a mean of 0.5 ng/ml of TNF-α. Bars represent mean percent change in protein levels ± s.e.m. of three independent experiments. Values for wild type cells (B6) for each experiment were normalized to 100% and other values are shown relative to B6. Because of the normalization, the s.e.m. for B6 is zero and no error bars are visible, * p<0.05.
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pone-0017414-g002: TLR2 independent intracellular signaling plays a role in the host response to B. burgdorferi signaling.BMDM from wild type and TLR2 deficient mice were stimulated with B. burgdorferi (MOI 10) for 6 hours and supernatants were collected. Concanamycin A (100 ng/ml) was added 30 minutes prior to stimulation. Cytokine levels in supernatants were measured by ELISA. Bars represent mean percent change in protein levels ± s.e.m. of three independent experiments. Wild type cells secreted a mean of 3.51 ng/ml, TLR2 deficient cells a mean of 1.65 ng/ml, and TLR2 deficient concanamycin treated cells a mean of 0.5 ng/ml of TNF-α. Bars represent mean percent change in protein levels ± s.e.m. of three independent experiments. Values for wild type cells (B6) for each experiment were normalized to 100% and other values are shown relative to B6. Because of the normalization, the s.e.m. for B6 is zero and no error bars are visible, * p<0.05.

Mentions: Having confirmed the requirement for internalization and endosomal maturation in activating murine BMDM responses to B. burgdorferi, we next sought to determine whether TLR2 signaling accounts for the entirety of this response. TLR2 is a major innate immune receptor which mediates responses to B. burgdorferi and signals from within the phagolysosome in response to B. burgdorferi in human macrophages [35]. To determine if TLR2 is the only intracellular signaling molecule that activates pro-inflammatory pathways in BMDM in response to B. burgdorferi, we treated TLR2 deficient BMDM with concanamycin A or sham. B. burgdorferi (MOI = 10) was then added to the treated cells. ELISAs performed on supernatants collected after 6 hours of incubation showed that the addition of concanamycin A to the TLR2 deficient cells resulted in a further decrease in the secretion of TNF-α by 30% in comparison to TLR2 deficient cells not treated with concanamycin (Figure 2). This suggests that intracellular receptors other than TLR2 also contribute to TNF-α induction in response to B. burgdorferi.


Nod2 suppresses Borrelia burgdorferi mediated murine Lyme arthritis and carditis through the induction of tolerance.

Petnicki-Ocwieja T, DeFrancesco AS, Chung E, Darcy CT, Bronson RT, Kobayashi KS, Hu LT - PLoS ONE (2011)

TLR2 independent intracellular signaling plays a role in the host response to B. burgdorferi signaling.BMDM from wild type and TLR2 deficient mice were stimulated with B. burgdorferi (MOI 10) for 6 hours and supernatants were collected. Concanamycin A (100 ng/ml) was added 30 minutes prior to stimulation. Cytokine levels in supernatants were measured by ELISA. Bars represent mean percent change in protein levels ± s.e.m. of three independent experiments. Wild type cells secreted a mean of 3.51 ng/ml, TLR2 deficient cells a mean of 1.65 ng/ml, and TLR2 deficient concanamycin treated cells a mean of 0.5 ng/ml of TNF-α. Bars represent mean percent change in protein levels ± s.e.m. of three independent experiments. Values for wild type cells (B6) for each experiment were normalized to 100% and other values are shown relative to B6. Because of the normalization, the s.e.m. for B6 is zero and no error bars are visible, * p<0.05.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3046161&req=5

pone-0017414-g002: TLR2 independent intracellular signaling plays a role in the host response to B. burgdorferi signaling.BMDM from wild type and TLR2 deficient mice were stimulated with B. burgdorferi (MOI 10) for 6 hours and supernatants were collected. Concanamycin A (100 ng/ml) was added 30 minutes prior to stimulation. Cytokine levels in supernatants were measured by ELISA. Bars represent mean percent change in protein levels ± s.e.m. of three independent experiments. Wild type cells secreted a mean of 3.51 ng/ml, TLR2 deficient cells a mean of 1.65 ng/ml, and TLR2 deficient concanamycin treated cells a mean of 0.5 ng/ml of TNF-α. Bars represent mean percent change in protein levels ± s.e.m. of three independent experiments. Values for wild type cells (B6) for each experiment were normalized to 100% and other values are shown relative to B6. Because of the normalization, the s.e.m. for B6 is zero and no error bars are visible, * p<0.05.
Mentions: Having confirmed the requirement for internalization and endosomal maturation in activating murine BMDM responses to B. burgdorferi, we next sought to determine whether TLR2 signaling accounts for the entirety of this response. TLR2 is a major innate immune receptor which mediates responses to B. burgdorferi and signals from within the phagolysosome in response to B. burgdorferi in human macrophages [35]. To determine if TLR2 is the only intracellular signaling molecule that activates pro-inflammatory pathways in BMDM in response to B. burgdorferi, we treated TLR2 deficient BMDM with concanamycin A or sham. B. burgdorferi (MOI = 10) was then added to the treated cells. ELISAs performed on supernatants collected after 6 hours of incubation showed that the addition of concanamycin A to the TLR2 deficient cells resulted in a further decrease in the secretion of TNF-α by 30% in comparison to TLR2 deficient cells not treated with concanamycin (Figure 2). This suggests that intracellular receptors other than TLR2 also contribute to TNF-α induction in response to B. burgdorferi.

Bottom Line: The internalization of Borrelia burgdorferi, the causative agent of Lyme disease, by phagocytes is essential for an effective activation of the immune response to this pathogen.In vitro stimulation of Nod2 deficient bone marrow derived macrophages (BMDM) resulted in decreased induction of multiple cytokines, interferons and interferon regulated genes compared with wild-type cells.However, B. burgdorferi infection of Nod2 deficient mice resulted in increased rather than decreased arthritis and carditis compared to control mice.

View Article: PubMed Central - PubMed

Affiliation: Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Boston, Massachusetts, United States of America.

ABSTRACT
The internalization of Borrelia burgdorferi, the causative agent of Lyme disease, by phagocytes is essential for an effective activation of the immune response to this pathogen. The intracellular, cytosolic receptor Nod2 has been shown to play varying roles in either enhancing or attenuating inflammation in response to different infectious agents. We examined the role of Nod2 in responses to B. burgdorferi. In vitro stimulation of Nod2 deficient bone marrow derived macrophages (BMDM) resulted in decreased induction of multiple cytokines, interferons and interferon regulated genes compared with wild-type cells. However, B. burgdorferi infection of Nod2 deficient mice resulted in increased rather than decreased arthritis and carditis compared to control mice. We explored multiple potential mechanisms for the paradoxical response in in vivo versus in vitro systems and found that prolonged stimulation with a Nod2 ligand, muramyl dipeptide (MDP), resulted in tolerance to stimulation by B. burgdorferi. This tolerance was lost with stimulation of Nod2 deficient cells that cannot respond to MDP. Cytokine patterns in the tolerance model closely paralleled cytokine profiles in infected Nod2 deficient mice. We propose a model where Nod2 has an enhancing role in activating inflammation in early infection, but moderates inflammation after prolonged exposure to the organism through induction of tolerance.

Show MeSH
Related in: MedlinePlus