[The interaction between saliva and cigarette smoke and its devastating biological effects as related to oral cancer]

Saliva is the first body fluid to confront inhaled cigarette smoke (CS) which is injurious to the oral cavity and is associated with several oral diseases and cancer. We have recently demonstrated in an In vitro model that an exposure of saliva to nine 'puffs' of CS induced a distinct increase in protein carbonyls. This elevation of protein carbonyls caused by CS may be the result of aldehydes presented in the CS reacting with sulphydryl (-SH) groups of the proteins. Moreover, following the exposure to CS, the activities of several salivary enzymes amylase, lactate dehydrogenase (LDH) and acid phosphatase (ACP) were found to be significantly reduced by 83%, 57% and 77%, respectively. However, CS had no effect on the activities of aspartate aminotransferase and alkaline phosphatase. In the current study we found that CS also reduced salivary peroxidase activity by no less than 80% which may be of a great importance to the clinical set up as peroxidase is considered a pivotal enzyme of the the salivary protecting system. Furthermore, in contrast to LDH findings in saliva, the LDH activity in plasma was not reduced following its exposure to CS.

Hence, we concluded that the loss of salivary enzyme activities may be due to various agents in the CS that affect the enzyme via different mechanisms.