Visit our Expo - Redox and Inflammation signaling 2012

VIII. Inflammation specific signaling Poster VIII, 1
Analysis of tissue distribution of TNF-alpha, TNF-alpha-Receptors and the activating
TNF-alpha-Converting Enzyme (TACE) suggest activation of the TNF-alpha system in
the ageing intervertebral disc
B.Bachmeier (1), A. Nerlich (2), Ch. Weiler (3), N. Boos (4)
Dept. of Clinical Chemistry Clin. Biochemistry, Univ. Munich, Germany,
bachmeier@med.uni-muenchen.de
Dept. of Pathology, Academic Hospital Munich-Bogenhausen, Germany
Institute of Pathology, Ludwig-Maximilians-University Munich, Germany
Spinal Surgery Unit, Orthopaedic Clinic, Univ. Zürich, Switzerland
The expression and up-regulation of the pro-inflammatory cytokine TNF-alpha recently has
been suggested to play a major role in the degeneration of the intervertebral disc. In order to
further elucidate the role of TNF-alpha in intervertebral discs and to find out, if the TNFalpha
activation by the corresponding converting enzyme TACE and the two TNF-alphareceptors
I and II are indeed potentially involved in the cytokine action, we
immunohistochemically analyzed the expression and localization of all four factors in human
discs. In parallel, the quantitative levels of TNF-alpha-mRNA (by quantitative RT-PCR) were
determined.
Therefore, a series of 43 human lumbar intervertebral disc samples with complete crosssection
of the motion segment were immunohistochemically stained for TNF-alpha, TNFR-I
and –II and TACE (all antibodies: Santa Cruz Biotech., CA, USA) and morphometrically
evaluated for the proportion of positively labelled cells in five anatomic sub-settings: nucleus
pulposus, inner and outer anterior and posterior annulus fibrosus. In a further series of
surgical material from 20 symptomatic patients the level of TNF-alpha-mRNA was
determined by quantitative RT-PCR (Light Cycler, Roche, Penzberg) and correlated to the
corresponding immunohistochemical staining pattern.
Thereby, we detected a significant expression of TNF-alpha beginning in advanced
adolescence (ca. 17 years) and being most extensive in the nucleus pulposus. Likewise, the
TNF-alpha expression in adult nucleus pulposus ranges between 27 – 80% of all cells until
senile age. In the inner and outer annulus fibrosus significantly less cells are labelled (0 –
50%). In fetal and juvenile discs no TNF-alpha expression is detectable. The parallel analyses
both TNF-alpha-receptors revealed a similar distribution pattern with respect to age and
localization. Additionally, the TNF-alpha converting enzyme TACE, which is essential for the
shedding and activation of the cytokine, are up-regulated similarly. The number of TNFalpha-transcripts
was elevated in most cases with immunohistochemical TNF-alpha
expression confirming the synthesis of TNF-alpha protein in the discs.
Our present study clearly supports the recent notion that TNF-alpha is expressed in discs of
increasing age. Furthermore, we also can confirm the previous observation that TNF-alpha
correlates with histomorphological signs of disc degeneration. Additionally, the present study
provides unambiguous evidence that TNF-alpha is activated (by the converting enzyme
TACE). Finally, the presence of both biologically active TNF-alpha receptors (TNFR-I and –
II) in similar proportion to each other supports the idea that TNF-alpha can also exhibit its
action within the disc.
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