A histochemical study of arylaminopeptidases in hydantoin induced hyperplastic, healthy and inflamed human gingiva

Abstract

Arylaminopeptidase activity in hydantoin induced hyperplastic, inflamed and healthy human gingiva was studied using various N‐L‐aminoacyl‐2‐naphthylamines as substrates. The activity was seen to be located in the basal cell layer of the epithelium in the entire connective tissue, but it was strongest just below the epithelium in all tissues. High enzymic activity was also observed in the inflammatory cells as well as in the capillary walls of hydantoinhyperplastic and inflamed gingiva. Strong enzymic activity was obtained when N‐L‐alanyl‐, N‐L‐methionyl‐ and N‐L‐leacyl‐2‐naphthylamine were used as substrates. Moderate activity was observed with N‐L‐arginyl‐2‐naphthylamine and N‐Llysyl‐2‐naphthylamine in other tissues except in healthy gingiva where the enzymic activity was low or nil. To test the possible involvement of aminopeptidase B in the material the reactions were performed both in the presence and absence of 0.2 M sodium chloride, which specifically activates this enzyme. There was no observable enzymic activity in any slices when N‐L‐prolyl‐2‐naphthylamine was used as substrate. The role of different arylaminopeptidases in connection with gingival hyperplasia caused by diphenylhydantoin and the evident absence of enzymes specific to N‐L‐prolyl‐2‐naphthylamine are discussed.

A histochemical study of glycosidases in hydantoin induced hyperplastic, healthy and inflamed human gingiva

“…The findings that /j-glucuronidase activity was localized in the basal cell layer, whereas weak /j-galactosidase was seen in the whole thickness of the gingival epithelium, is similar to that reported earlier of the distribution of these enzymes in the oral epithelium of the stomodeum (Larmas & Larmas 1973). The intracellular localization of these glycosidases especially of /?glucoronidase, would suggest that these enzymes are lysosomal.…”

“…Previous studies on hydantoin induced hyperplastic gingiva with both animal and human material would indicate that no gingival enlargement occurs without local irritants producing inflammation observed at clinical and histological levels (Aas 1963, Nuki & Cooper 1972). This concept is partly supported by recent enzyme histochemical findings that the release of a group of lysosomal hydrolases (peptidyl peptide hydrolases, FC 3.4.11) could be observed both in inflamed and hyperplastic human gingiva, whereas clinically and histologically healthy gingiva revealed only slight activity with the substrates studied (Larmas, Makinen & Paunio 1973). This activation and/or liberation of peptidases was observed to characterize both hyperplasia and inflammation, but the question, of whether inflammation is a primary process in hyperplasia was left open.…”