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Neuroimmune and Neuropathic Responses of Spinal Cord and Dorsal Root Ganglia in Middle Age.

Galbavy W, Kaczocha M, Puopolo M, Liu L, Rebecchi MJ - PLoS ONE (2015)

Bottom Line: Results showed that CD2, CD3e, CD68, CD45, TNF-α, IL6, CCL2, ATF3 and TGFβ1 mRNA levels were substantially elevated in LSC from naïve middle-aged animals compared to young adults.The patterns of marker expression and microglial morphologies in healthy middle age are consistent with development of a para-inflammatory state involving microglial activation and T-cell marker elevation in the dorsal horn, and neuronal stress and satellite cell activation in the DRG.These changes, however, did not affect the establishment of neuropathic pain.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
Prior studies of aging and neuropathic injury have focused on senescent animals compared to young adults, while changes in middle age, particularly in the dorsal root ganglia (DRG), have remained largely unexplored. 14 neuroimmune mRNA markers, previously associated with peripheral nerve injury, were measured in multiplex assays of lumbar spinal cord (LSC), and DRG from young and middle-aged (3, 17 month) naïve rats, or from rats subjected to chronic constriction injury (CCI) of the sciatic nerve (after 7 days), or from aged-matched sham controls. Results showed that CD2, CD3e, CD68, CD45, TNF-α, IL6, CCL2, ATF3 and TGFβ1 mRNA levels were substantially elevated in LSC from naïve middle-aged animals compared to young adults. Similarly, LSC samples from older sham animals showed increased levels of T-cell and microglial/macrophage markers. CCI induced further increases in CCL2, and IL6, and elevated ATF3 mRNA levels in LSC of young and middle-aged adults. Immunofluorescence images of dorsal horn microglia from middle-aged naïve or sham rats were typically hypertrophic with mostly thickened, de-ramified processes, similar to microglia following CCI. Unlike the spinal cord, marker expression profiles in naïve DRG were unchanged across age (except increased ATF3); whereas, levels of GFAP protein, localized to satellite glia, were highly elevated in middle age, but independent of nerve injury. Most neuroimmune markers were elevated in DRG following CCI in young adults, yet middle-aged animals showed little response to injury. No age-related changes in nociception (heat, cold, mechanical) were observed in naïve adults, or at days 3 or 7 post-CCI. The patterns of marker expression and microglial morphologies in healthy middle age are consistent with development of a para-inflammatory state involving microglial activation and T-cell marker elevation in the dorsal horn, and neuronal stress and satellite cell activation in the DRG. These changes, however, did not affect the establishment of neuropathic pain.

No MeSH data available.


Related in: MedlinePlus

Representative Iba1 immunofluorescence images of young and middle aged of lumbar spinal cord dorsal horns from post-CCI day 7 animals, ipsilateral or contralateral to injury.Immunofluorescence confocal images of the dorsal horns stained with Iba1 antibody were combined with corresponding transmitted light images. Young (YCCI) and middle-aged (MCCI) dorsal horns ipsilateral (IPSL) to injury are compared to the contralateral (CL) sides. Scale bars = 100 μm.
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pone.0134394.g004: Representative Iba1 immunofluorescence images of young and middle aged of lumbar spinal cord dorsal horns from post-CCI day 7 animals, ipsilateral or contralateral to injury.Immunofluorescence confocal images of the dorsal horns stained with Iba1 antibody were combined with corresponding transmitted light images. Young (YCCI) and middle-aged (MCCI) dorsal horns ipsilateral (IPSL) to injury are compared to the contralateral (CL) sides. Scale bars = 100 μm.

Mentions: To assess whether age affected the morphologic, and proliferative or migratory responses of microglia to injury, LSC from CCI animals were fixed in situ, frozen, sectioned and stained with Iba1. Microglia, stained with Iba1, accumulated in the LSC IPSL dorsal horns of young and middle-aged animals 7 days post-CCI. Both age groups showed a concentration of highly fluorescent microglia adjacent to the most lateral aspect of the dorsal tract in the superficial dorsal horn and towards the center (Fig 4). High-resolution two-photon image stacks of contralateral (CL) and ipsilateral (IPSL) dorsal horn microglia from CCI animals were obtained. 3D images were reconstructed from these stacks and are displayed in a single view plane (Fig 5; for 3D rotatable images of dorsal horn microglia from animals subjected to CCI, see S3–S6 Files). Both young and middle-aged CCI IPSL microglia exhibited hypertrophic cell bodies and de-ramified processes (Fig 5, right panels) consistent with activated morphologies previously described in nerve injured animals [28]. In the contralateral dorsal horn, MCCI microglia were noticeably different from their young counterparts, with larger cell bodies and shorter, stouter processes with less branching (Fig 5, middle panels). Thus, CL MCCI microglia were distinct from the CL YCCI, but similar to the naïve middle-aged microglia described above.


Neuroimmune and Neuropathic Responses of Spinal Cord and Dorsal Root Ganglia in Middle Age.

Galbavy W, Kaczocha M, Puopolo M, Liu L, Rebecchi MJ - PLoS ONE (2015)

Representative Iba1 immunofluorescence images of young and middle aged of lumbar spinal cord dorsal horns from post-CCI day 7 animals, ipsilateral or contralateral to injury.Immunofluorescence confocal images of the dorsal horns stained with Iba1 antibody were combined with corresponding transmitted light images. Young (YCCI) and middle-aged (MCCI) dorsal horns ipsilateral (IPSL) to injury are compared to the contralateral (CL) sides. Scale bars = 100 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4524632&req=5

pone.0134394.g004: Representative Iba1 immunofluorescence images of young and middle aged of lumbar spinal cord dorsal horns from post-CCI day 7 animals, ipsilateral or contralateral to injury.Immunofluorescence confocal images of the dorsal horns stained with Iba1 antibody were combined with corresponding transmitted light images. Young (YCCI) and middle-aged (MCCI) dorsal horns ipsilateral (IPSL) to injury are compared to the contralateral (CL) sides. Scale bars = 100 μm.
Mentions: To assess whether age affected the morphologic, and proliferative or migratory responses of microglia to injury, LSC from CCI animals were fixed in situ, frozen, sectioned and stained with Iba1. Microglia, stained with Iba1, accumulated in the LSC IPSL dorsal horns of young and middle-aged animals 7 days post-CCI. Both age groups showed a concentration of highly fluorescent microglia adjacent to the most lateral aspect of the dorsal tract in the superficial dorsal horn and towards the center (Fig 4). High-resolution two-photon image stacks of contralateral (CL) and ipsilateral (IPSL) dorsal horn microglia from CCI animals were obtained. 3D images were reconstructed from these stacks and are displayed in a single view plane (Fig 5; for 3D rotatable images of dorsal horn microglia from animals subjected to CCI, see S3–S6 Files). Both young and middle-aged CCI IPSL microglia exhibited hypertrophic cell bodies and de-ramified processes (Fig 5, right panels) consistent with activated morphologies previously described in nerve injured animals [28]. In the contralateral dorsal horn, MCCI microglia were noticeably different from their young counterparts, with larger cell bodies and shorter, stouter processes with less branching (Fig 5, middle panels). Thus, CL MCCI microglia were distinct from the CL YCCI, but similar to the naïve middle-aged microglia described above.

Bottom Line: Results showed that CD2, CD3e, CD68, CD45, TNF-α, IL6, CCL2, ATF3 and TGFβ1 mRNA levels were substantially elevated in LSC from naïve middle-aged animals compared to young adults.The patterns of marker expression and microglial morphologies in healthy middle age are consistent with development of a para-inflammatory state involving microglial activation and T-cell marker elevation in the dorsal horn, and neuronal stress and satellite cell activation in the DRG.These changes, however, did not affect the establishment of neuropathic pain.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
Prior studies of aging and neuropathic injury have focused on senescent animals compared to young adults, while changes in middle age, particularly in the dorsal root ganglia (DRG), have remained largely unexplored. 14 neuroimmune mRNA markers, previously associated with peripheral nerve injury, were measured in multiplex assays of lumbar spinal cord (LSC), and DRG from young and middle-aged (3, 17 month) naïve rats, or from rats subjected to chronic constriction injury (CCI) of the sciatic nerve (after 7 days), or from aged-matched sham controls. Results showed that CD2, CD3e, CD68, CD45, TNF-α, IL6, CCL2, ATF3 and TGFβ1 mRNA levels were substantially elevated in LSC from naïve middle-aged animals compared to young adults. Similarly, LSC samples from older sham animals showed increased levels of T-cell and microglial/macrophage markers. CCI induced further increases in CCL2, and IL6, and elevated ATF3 mRNA levels in LSC of young and middle-aged adults. Immunofluorescence images of dorsal horn microglia from middle-aged naïve or sham rats were typically hypertrophic with mostly thickened, de-ramified processes, similar to microglia following CCI. Unlike the spinal cord, marker expression profiles in naïve DRG were unchanged across age (except increased ATF3); whereas, levels of GFAP protein, localized to satellite glia, were highly elevated in middle age, but independent of nerve injury. Most neuroimmune markers were elevated in DRG following CCI in young adults, yet middle-aged animals showed little response to injury. No age-related changes in nociception (heat, cold, mechanical) were observed in naïve adults, or at days 3 or 7 post-CCI. The patterns of marker expression and microglial morphologies in healthy middle age are consistent with development of a para-inflammatory state involving microglial activation and T-cell marker elevation in the dorsal horn, and neuronal stress and satellite cell activation in the DRG. These changes, however, did not affect the establishment of neuropathic pain.

No MeSH data available.


Related in: MedlinePlus