Lysozyme is an innate non-immunologic antibacterial
enzyme produced by the Paneth cells of the upper intestinal tract.
Lysozyme is not normally secreted in the lower intestinal tract. Previous reports indicate, however, that
lysozyme may be secreted by colorectal
neoplasias. The aim was to audit
lysozyme expression in colorectal diseases including
neoplasias. For that purpose, sections were stained with
lysozyme (
Muramidase), Ki67 (MIB1) and CD 68. Intense
lysozyme overexpression (+++) was compared among 177 colorectal tissues: 35 having normal mucosa, 20 regenerative mucosa in
inflammatory bowel disease (IBD), 2 inflammatory
polyps, 3
collagenous colitis, 2
melanosis coli, 21 hyperplastic
polyps, 42 tubular
adenomas, 9 serrated
adenomas, 30
villous adenomas and 13 invasive
carcinomas. Intense
lysozyme overexpression (+++) was found in 9.5% of the hyperplastic
polyps, in 97.6% of the tubular
adenomas, in 88.9% of the serrated
adenomas, in 93.3% of the
villous adenomas, in 76.9% of the
carcinomas, but in none of the other tissues investigated. Neoplastic colorectal cells may acquire the capacity to produce
lysozyme. The presence of that
enzyme may not be a haphazard, capricious event in mutated colorectal epithelial cells but part of a more elaborate molecular behavior, not necessarily antibacterial. Recently, it was demonstrated that patients having
lysozyme-secreting
breast carcinomas were associated with a favorable prognosis. Whether
lysozyme expression has any bearing on the
biological behavior of
colorectal carcinomas remains to be elucidated.
Lysozyme overexpression (+++) also occurred in 2 of the 21 hyperplastic
polyps, suggesting that intense
lysozyme production might herald a possible dysplastic evolution in some hyperplastic
polyps.