Immunomorphological analysis of RAGE receptor expression and NF-kappaB activation in tissue samples from normal and degenerated intervertebral discs of various ages.

We immunohistochemically investigated the pattern of RAGE expression and NFkappaB translocation into the nucleus in 43 complete cross-sections of human lumbar intervertebral discs (neonatal-85 years) and compared this with the carboxymethyl-lysine (CML) modification of proteins as a marker for oxidative stress. No significant expression of RAGE, no obvious activation of NF-kappaB, and no deposition of CML-modified proteins were seen in fetal, juvenile, and young adolescent discs (until age of 13 years). In adults, 25-50% of nucleus pulposus cells were labeled for RAGE and activated NF-kappaB, which correlated well with the occurrence and extent of CML staining in the pericellular matrix. In the annulus fibrosus significantly lower values were seen than in the nucleus pulposus. In consequence, we provide evidence for activation of the NF-kappaB system in intervertebral discs in vivo, which correlates with accumulated oxidative stress and increases in age and disc degeneration. Oxidative stress (as monitored by CML modifications) may lead to RAGE activation and NF-kappaB translocation.