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The Lyme disease spirochete Borrelia burgdorferi induces inflammation and apoptosis in cells from dorsal root ganglia.

Ramesh G, Santana-Gould L, Inglis FM, England JD, Philipp MT - J Neuroinflammation (2013)

Bottom Line: Dexamethasone reduced the levels of immune mediators and neuronal apoptosis in a dose dependent manner.In this model, B. burgdorferi induced an inflammatory response and neuronal apoptosis of DRG.These pathophysiological processes could contribute to peripheral neuropathy in LNB.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Bacteriology and Parasitology, Tulane National Primate Research Center, Covington, LA, USA.

ABSTRACT

Background: Lyme neuroborreliosis (LNB), caused by the spirochete Borrelia burgdorferi, affects both the peripheral and the central nervous systems. Radiculitis or nerve root inflammation, which can cause pain, sensory loss, and weakness, is the most common manifestation of peripheral LNB in humans. We previously reported that rhesus monkeys infected with B. burgdorferi develop radiculitis as well as inflammation in the dorsal root ganglia (DRG), with elevated levels of neuronal and satellite glial cell apoptosis in the DRG. We hypothesized that B. burgdorferi induces inflammatory mediators in glial and neuronal cells and that this inflammatory milieu precipitates glial and neuronal apoptosis.

Methods: To model peripheral neuropathy in LNB we incubated normal rhesus DRG tissue explants with live B. burgdorferi ex vivo and identified immune mediators, producer cells, and verified the presence of B. burgdorferi in tissue sections by immunofluorescence staining and confocal microscopy. We also set up primary cultures of DRG cells from normal adult rhesus macaques and incubated the cultures with live B. burgdorferi. Culture supernatants were subjected to multiplex ELISA to detect immune mediators, while the cells were evaluated for apoptosis by the in situ TUNEL assay. A role for inflammation in mediating apoptosis was assessed by evaluating the above phenomena in the presence and absence of various concentrations of the anti-inflammatory drug dexamethasone. As Schwann cells ensheath the dorsal roots of the DRG, we evaluated the potential of live B. burgdorferi to induce inflammatory mediators in human Schwann cell (HSC) cultures.

Results: Rhesus DRG tissue explants exposed to live B. burgdorferi showed localization of CCL2 and IL-6 in sensory neurons, satellite glial cells and Schwann cells while IL-8 was seen in satellite glial cells and Schwann cells. Live B. burgdorferi induced elevated levels of IL-6, IL-8 and CCL2 in HSC and DRG cultures and apoptosis of sensory neurons. Dexamethasone reduced the levels of immune mediators and neuronal apoptosis in a dose dependent manner.

Conclusion: In this model, B. burgdorferi induced an inflammatory response and neuronal apoptosis of DRG. These pathophysiological processes could contribute to peripheral neuropathy in LNB.

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Effect of dexamethasone on the pro-inflammatory response elicited by B. burgdorferi in primary rhesus DRG cultures. The levels of CCL2 (A), IL-6 (B) and IL-8 (C), respectively, in rhesus DRG cultures stimulated with live B. burgdorferi spirochetes for 24 hours at a MOI of 10:1 and in medium controls (* P <0.05, ** P <0.01) in the presence and absence of dexamethasone and carrier HPC are shown. Data represent mean values and standard deviations between values of duplicate wells that were seeded from DRG cells that were isolated from two adult rhesus macaques. DRG, dorsal root ganglia; HPC, (2-hydroxypropyl)-β-cyclodextrin; MOI, multiplicity of infection.
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Figure 4: Effect of dexamethasone on the pro-inflammatory response elicited by B. burgdorferi in primary rhesus DRG cultures. The levels of CCL2 (A), IL-6 (B) and IL-8 (C), respectively, in rhesus DRG cultures stimulated with live B. burgdorferi spirochetes for 24 hours at a MOI of 10:1 and in medium controls (* P <0.05, ** P <0.01) in the presence and absence of dexamethasone and carrier HPC are shown. Data represent mean values and standard deviations between values of duplicate wells that were seeded from DRG cells that were isolated from two adult rhesus macaques. DRG, dorsal root ganglia; HPC, (2-hydroxypropyl)-β-cyclodextrin; MOI, multiplicity of infection.

Mentions: Live B. burgdorferi spirochetes incubated with rhesus DRG cultures for 24 hours at a MOI of 10:1 induced significantly elevated levels of CCL2 (Figure 4A), IL-6 (Figure 4B) and IL-8 (Figure 4C) compared to the levels induced in medium controls. The concentration of CCL2 surpassed 20,000 pg/mL, whereas the constitutive level of this chemokine that was produced in medium alone was around 8,000 pg/mL (Figure 4A). The basal concentration of IL-6 was 4,000 pg/mL but reached almost 8,000 pg/mL (Figure 4B) and the basal level of IL-8 production in DRG cultures was around 800 pg/mL but reached about 5,000 pg/mL when stimulated with live B. burgdorferi for 24 hours (Figure 4C).


The Lyme disease spirochete Borrelia burgdorferi induces inflammation and apoptosis in cells from dorsal root ganglia.

Ramesh G, Santana-Gould L, Inglis FM, England JD, Philipp MT - J Neuroinflammation (2013)

Effect of dexamethasone on the pro-inflammatory response elicited by B. burgdorferi in primary rhesus DRG cultures. The levels of CCL2 (A), IL-6 (B) and IL-8 (C), respectively, in rhesus DRG cultures stimulated with live B. burgdorferi spirochetes for 24 hours at a MOI of 10:1 and in medium controls (* P <0.05, ** P <0.01) in the presence and absence of dexamethasone and carrier HPC are shown. Data represent mean values and standard deviations between values of duplicate wells that were seeded from DRG cells that were isolated from two adult rhesus macaques. DRG, dorsal root ganglia; HPC, (2-hydroxypropyl)-β-cyclodextrin; MOI, multiplicity of infection.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3721987&req=5

Figure 4: Effect of dexamethasone on the pro-inflammatory response elicited by B. burgdorferi in primary rhesus DRG cultures. The levels of CCL2 (A), IL-6 (B) and IL-8 (C), respectively, in rhesus DRG cultures stimulated with live B. burgdorferi spirochetes for 24 hours at a MOI of 10:1 and in medium controls (* P <0.05, ** P <0.01) in the presence and absence of dexamethasone and carrier HPC are shown. Data represent mean values and standard deviations between values of duplicate wells that were seeded from DRG cells that were isolated from two adult rhesus macaques. DRG, dorsal root ganglia; HPC, (2-hydroxypropyl)-β-cyclodextrin; MOI, multiplicity of infection.
Mentions: Live B. burgdorferi spirochetes incubated with rhesus DRG cultures for 24 hours at a MOI of 10:1 induced significantly elevated levels of CCL2 (Figure 4A), IL-6 (Figure 4B) and IL-8 (Figure 4C) compared to the levels induced in medium controls. The concentration of CCL2 surpassed 20,000 pg/mL, whereas the constitutive level of this chemokine that was produced in medium alone was around 8,000 pg/mL (Figure 4A). The basal concentration of IL-6 was 4,000 pg/mL but reached almost 8,000 pg/mL (Figure 4B) and the basal level of IL-8 production in DRG cultures was around 800 pg/mL but reached about 5,000 pg/mL when stimulated with live B. burgdorferi for 24 hours (Figure 4C).

Bottom Line: Dexamethasone reduced the levels of immune mediators and neuronal apoptosis in a dose dependent manner.In this model, B. burgdorferi induced an inflammatory response and neuronal apoptosis of DRG.These pathophysiological processes could contribute to peripheral neuropathy in LNB.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Bacteriology and Parasitology, Tulane National Primate Research Center, Covington, LA, USA.

ABSTRACT

Background: Lyme neuroborreliosis (LNB), caused by the spirochete Borrelia burgdorferi, affects both the peripheral and the central nervous systems. Radiculitis or nerve root inflammation, which can cause pain, sensory loss, and weakness, is the most common manifestation of peripheral LNB in humans. We previously reported that rhesus monkeys infected with B. burgdorferi develop radiculitis as well as inflammation in the dorsal root ganglia (DRG), with elevated levels of neuronal and satellite glial cell apoptosis in the DRG. We hypothesized that B. burgdorferi induces inflammatory mediators in glial and neuronal cells and that this inflammatory milieu precipitates glial and neuronal apoptosis.

Methods: To model peripheral neuropathy in LNB we incubated normal rhesus DRG tissue explants with live B. burgdorferi ex vivo and identified immune mediators, producer cells, and verified the presence of B. burgdorferi in tissue sections by immunofluorescence staining and confocal microscopy. We also set up primary cultures of DRG cells from normal adult rhesus macaques and incubated the cultures with live B. burgdorferi. Culture supernatants were subjected to multiplex ELISA to detect immune mediators, while the cells were evaluated for apoptosis by the in situ TUNEL assay. A role for inflammation in mediating apoptosis was assessed by evaluating the above phenomena in the presence and absence of various concentrations of the anti-inflammatory drug dexamethasone. As Schwann cells ensheath the dorsal roots of the DRG, we evaluated the potential of live B. burgdorferi to induce inflammatory mediators in human Schwann cell (HSC) cultures.

Results: Rhesus DRG tissue explants exposed to live B. burgdorferi showed localization of CCL2 and IL-6 in sensory neurons, satellite glial cells and Schwann cells while IL-8 was seen in satellite glial cells and Schwann cells. Live B. burgdorferi induced elevated levels of IL-6, IL-8 and CCL2 in HSC and DRG cultures and apoptosis of sensory neurons. Dexamethasone reduced the levels of immune mediators and neuronal apoptosis in a dose dependent manner.

Conclusion: In this model, B. burgdorferi induced an inflammatory response and neuronal apoptosis of DRG. These pathophysiological processes could contribute to peripheral neuropathy in LNB.

Show MeSH
Related in: MedlinePlus