Neuropeptide degradation in naive and steroid-treated allergic saliva

Abstract

The hydrolysis of neuropeptides and possible variations in hydrolysis following steroidal treatment, were examined in the presence of saliva collected from allergic volunteers; data obtained were compared to those obtained with a age and sex-matching group of healthy controls. The results reported indicate the presence of a statistically significant increase in the hydrolysis of the model substrate in allergic as compared to control saliva, and a reduction of substrate hydrolysis in treated as compared to naive allergic saliva. Total enzyme activity, the relative activity of the three classes of substrate-active enzymes (aminopeptidases, dipeptidylaminopeptidases, and dipeptidylcarboxypeptidases), the allergy-associated variations of these activities, and the variations associated to therapy were found to be different in male and female saliva. Specifically, in the controls, the lower level of hydrolysis evident in female as compared to male saliva appeared to be principally induced by lower activity of aminopeptidases. Under allergic conditions, a sex-different increase in the activity of all three classes of substrate-active enzymes modified the hydrolysis pattern differently in samples obtained from male and female donors. Finally, pharmacological treatment induced opposite effects on the enzymes present in each sex: in male saliva, the activity of all three classes of substrate-active enzymes—and, thus, of substrate hydrolysis—was reduced near to the levels measured in the controls. In female saliva, the reduction in the activity of aminopeptidases was coupled with an increase in the activity of dipeptidylaminopeptidases, causing substrate hydrolysis to remain near the levels measured in naive allergic, rather than control, saliva.