Salivary cytokines in cell proliferation and cancer

While the presence of multiple systemic steroids, amines and peptides in saliva has been reported, other hormones of the circulation do not appear in saliva. Substances present within saliva may be classified in different groups: first, those which passively display blood plasma concentrations and constitute a promising alternative to evaluate certain systemic parameters. Second, molecules which seem to play a more active, regulatory role within the upper gastrointestinal tract. Concerning the latter, a growing awareness, especially with regards to salivary peptides has been established. Up to now, understanding the distinct effects of salivary peptides known so far is in its infancy. Various publications, however, emphasize important effects of their presence. Salivary peptides can influence inflammatory processes and cell proliferation in epithelia of the upper digestive tract. These include transforming growth factors (TGFs), epidermal growth factors (EGFs), vascular endothelial growth factors (VEGFs) as well as amines such as melatonin. Of those, candidate cytokines like interleukin 8, tumor necrosis factors (TNFs) and leptin are involved in neoplastic activities of salivary glands and the oral cavity. The exact mechanisms of action are not yet completely understood, but their presence can be utilized for diagnostic purposes. Salivary gland tumors in patients may, in certain circumstances, be identified by saliva diagnostics. Saliva samples of the concerned patients, for instance, reveal significantly higher leptin concentrations than those of healthy individuals. Numerous studies postulate that, beside single indicators, the establishment of salivary hormone profiles may assist clinicians and researchers in detecting tumors and other pathologies of the oral cavity, including adjacent tissues, with high sensitivity and specificity.