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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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Expression of the neuronal marker NeuN and satellite glial cell markers GFAP and S-100 in primary rhesus DRG cultures. Primary rhesus DRG cultures showing a mat of sensory neurons staining positive for the neuronal marker NeuN (red) (A) and a few stray satellite glial cells staining positive for the glial cell markers S-100 and GFAP (B). The nuclei of all cells in A and B appear blue due to staining with the nuclear stain TOPRO3. DRG, dorsal root ganglia; GFAP, glial fibrillary acid protein.
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Figure 2: Expression of the neuronal marker NeuN and satellite glial cell markers GFAP and S-100 in primary rhesus DRG cultures. Primary rhesus DRG cultures showing a mat of sensory neurons staining positive for the neuronal marker NeuN (red) (A) and a few stray satellite glial cells staining positive for the glial cell markers S-100 and GFAP (B). The nuclei of all cells in A and B appear blue due to staining with the nuclear stain TOPRO3. DRG, dorsal root ganglia; GFAP, glial fibrillary acid protein.

Mentions: In order to permit a more detailed evaluation of the ability of B. burgdorferi spirochetes to elicit inflammation and apoptosis in DRG cells, we set up in vitro cultures of these cells and characterized their phenotypes. The primary rhesus DRG cultures consisted primarily of a mat of sensory neurons that stained positive for the neuronal marker NeuN and a few stray satellite glial cells that stained positive for the glial cell marker S-100 (Figure 2A). The satellite glial cells also showed the expression of GFAP (Figure 2B). The sensory neurons in the DRG cultures did not stain positive for S-100, contrary to what we had observed in sensory neurons within DRG tissue explants (Figure 1C and Figure 1F). The nuclei of all cells in Figure 2A and 2B appeared blue due to staining with the nuclear stain TOPRO3. DRG culture slides that were incubated with respective isotype controls of primary antibodies and corresponding secondary antibodies did not show any detectable signal (not shown). DRG cultures did not show specific staining with antibodies to the Schwann cell markers CNPase or p75NTR.


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)

Expression of the neuronal marker NeuN and satellite glial cell markers GFAP and S-100 in primary rhesus DRG cultures. Primary rhesus DRG cultures showing a mat of sensory neurons staining positive for the neuronal marker NeuN (red) (A) and a few stray satellite glial cells staining positive for the glial cell markers S-100 and GFAP (B). The nuclei of all cells in A and B appear blue due to staining with the nuclear stain TOPRO3. DRG, dorsal root ganglia; GFAP, glial fibrillary acid protein.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Expression of the neuronal marker NeuN and satellite glial cell markers GFAP and S-100 in primary rhesus DRG cultures. Primary rhesus DRG cultures showing a mat of sensory neurons staining positive for the neuronal marker NeuN (red) (A) and a few stray satellite glial cells staining positive for the glial cell markers S-100 and GFAP (B). The nuclei of all cells in A and B appear blue due to staining with the nuclear stain TOPRO3. DRG, dorsal root ganglia; GFAP, glial fibrillary acid protein.
Mentions: In order to permit a more detailed evaluation of the ability of B. burgdorferi spirochetes to elicit inflammation and apoptosis in DRG cells, we set up in vitro cultures of these cells and characterized their phenotypes. The primary rhesus DRG cultures consisted primarily of a mat of sensory neurons that stained positive for the neuronal marker NeuN and a few stray satellite glial cells that stained positive for the glial cell marker S-100 (Figure 2A). The satellite glial cells also showed the expression of GFAP (Figure 2B). The sensory neurons in the DRG cultures did not stain positive for S-100, contrary to what we had observed in sensory neurons within DRG tissue explants (Figure 1C and Figure 1F). The nuclei of all cells in Figure 2A and 2B appeared blue due to staining with the nuclear stain TOPRO3. DRG culture slides that were incubated with respective isotype controls of primary antibodies and corresponding secondary antibodies did not show any detectable signal (not shown). DRG cultures did not show specific staining with antibodies to the Schwann cell markers CNPase or p75NTR.

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