Transforming growth factor beta receptor induction in herniated intervertebral disc tissue: an immunohistochemical study.

Transforming growth factor beta (TGF-beta) is a potent inducer of angiogenesis and fibrogenesis. There is presently little information about the pathophysiological function of TGF-beta in herniated disc tissue. In order to analyze the cellular role and activation of TGF-beta after disc herniation we immunostained frozen material from 38 disc herniation operations and from eight macroscopically normal discs from organ donors. Polyclonal TGF-beta-I, TGF-beta-II and TGF-beta receptor type II antibodies were used with the avidin biotin complex (ABC-) immunoperoxidase method. All the herniated discs were TGF-beta immunopositive. Such immunoreactivity was mainly associated with disc cells. In a few samples, capillaries were also TGF-beta immunopositive. Immunopositivity was similarly observed in the control discs. To analyze possible differences between the two groups, we calculated the ratio of immunopositive disc cells. For all three antibodies, a statistically significantly (Mann-Whitney test, P = 0.0001) higher number of disc cells showed immunopositivity in the herniated discs. The increase in TGF-beta receptor immunopositivity suggested induction of TGF-beta receptors in herniated discs. Our results support an active regulatory role for TGF-beta in disc cell metabolism.