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Spine (Phila Pa 1976). 2013 Jan 1;38(1):17-23. doi: 10.1097/BRS.0b013e3182604baa.

Cytokine expression in the epidural space: a model of noncompressive disc herniation-induced inflammation.

Author information

1
Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY 10003, USA. Jason.cuellar@nyumc.org

Abstract

STUDY DESIGN:

Animal study.

OBJECTIVE:

Development of an animal model for the study of biochemical changes that occur in the epidural space after intervertebral disc herniation.

SUMMARY OF BACKGROUND DATA:

Although strong evidence for an inflammatory component exists, the biochemical processes underlying pain after disc herniation remain unknown.

METHODS:

Epidural lavage was performed in 48 rats after L5 dorsal root ganglion exposure at baseline and 3, 6, or 24 hours after placement of autologous nucleus pulposus (NP) (N = 15), saline (N = 15), or NP + an interferon-γ antibody (anti-IFN-γ; N = 18) directly onto the dorsal root ganglion. Multiplex assays quantifying interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor α (TNF-α), IFN-γ, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were performed. NP (N = 7) was also analyzed for these cytokines by placing NP into saline and measuring the relative concentration.

RESULTS:

Cytokines measured low at baseline (0-100 pg/mL) in all groups. Compared with saline, NP application caused IL-6 elevation, peaking at T = 3 hours, that was prevented by anti-IFN-γ. NP induced elevation of TNF-α, peaking at T = 24 hours and was prevented by anti-IFN-γ. IFN-γ was elevated after NP at T = 3 hours and T = 24 hours. IL-1α was similar after saline versus NP. The concentrations of IL-1β and IL-10 were elevated at T = 3 hours, 6 hours, and 24 hours in all groups without between-groups difference. The level of IL-4 peaked at T = 3 hours in the NP group and was different than saline and NP + anti-IFN-γ groups, but the time effect was insignificant. There was no change for GM-CSF. The concentration of cytokines measured in normal NP was less than 2 pg/mL for all cytokines except TNF-α.

CONCLUSION:

In this model of acute noncompressive disc herniation, NP caused the elevation of epidural IL-6, TNF-α, and IFN-γ--all attenuated by IFN-γ blockade. IL-1β and IL-10 were both significantly elevated by saline alone and their response was not prevented by IFN-γ blockade. This model may prove useful for the study of the biochemical processes by which NP induces inflammation-induced nerve root irritation and radiculopathic pain.

PMID:
22648034
PMCID:
PMC3505560
DOI:
10.1097/BRS.0b013e3182604baa
[Indexed for MEDLINE]
Free PMC Article
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