Residual chymopapain activity after chemonucleolysis in normal intervertebral discs in dogs
Oegema, T.R.; Swedenberg, S.; Johnson, S.L.; Madison, M.; Bradford, D.S.
Journal of Bone and Joint Surgery. American Volume 74(6): 831-838
1992
ISSN/ISBN: 0021-9355 PMID: 1634573 Document Number: 388573
Studies were carried out to demonstrate residual chymopapain activity in intervertebral discs after chemonucleolysis; protease assay, enzyme-linked immunosorbent assay, and immunohistochemical localization of the chymopapain in the disc tissue were done. Chymopapain, one milligram per level, was injected into the normal lumbar intervertebral discs of adult mongrel dogs and the discs were excised after two weeks. Proteolytically active chymopapain was still present in the extract of intervertebral disc at this time. The proteolytic activity was decreased by sulfhydryl inhibitors but not by inhibitors of metalloproteases or serine proteases. Protease and enzyme-linked immunosorbent assays showed that 0.60.+-.0.48 per cent and 0.49.+-.0.38 per cent of the original dose was present two weeks after the injection. Chymopapain was shown by immunohistochemical staining to be diffusely located throughout the extracellular matrix of the anulus fibrosus and the nucleus pulposus. Some cells, located mainly in the inner portion of the anulus, contained vacuoles filled with immunoreactive product. The persistence of proteolytic activity after the injection of chymopapain into normal tissue was unexpected. The constant exposure to low levels of chymopapin, which acts both as an antigen and as a protease, may partly explain some of the late complications that are associated with injection of chymopapain, such as transverse myelitis. It has been postulated that transverse myelitis after injection of chymopapain may have an immunological bases and may result from exposure to low doses of chymopapain, which leads to an inflammatory reaction. Since the presence of residual enzyme, along with other complications associated with chymopapain, can be related to the concentration, a re-evaluation of the lowest effective dose may be warranted.