Salivary Signal Molecules Relevant for Neural and Vascular Homeostasis in Patients With Type 2 Diabetes Mellitus

Various signal molecules are detected in blood and tissues of patients with T2DM, that are important for the function of neural tissue in diabetic setting. Among them, specifically important are neuroprotective and neurotrophic growth factors such as nerve growth factor (NGF), glial cells - derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF). Furthermore, several other signal molecules are discovered to affect vascular tissues homeostasis in T2DM, including soluble alpha-klotho (s-Klotho), vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6). Most of these molecules are also detected in saliva in various states and diseases of orofacial system, but data about their levels in saliva of T2DM patients are lacking, although neural and vascular diabetic complications are present in orofacial tissues and organs. Also, there is no data about presence and levels of s-Klotho in saliva of healthy or T2DM patients, although it was reported that this molecule exerts protective effect on the salivary glands tissue. Salivary opiorphin is recently discovered pentapeptide, primarily isolated from saliva. It acts as an inhibitor of the enzymes that perform degradation of endogenous antinociceptive molecules enkephalins, affecting nociceptive signal transduction. This may be of special importance since some intraoral complications of T2DM (e.g. burning mouth) may have underlying peripheral neural changes as a pathophysiological mechanism. Against this background, the aim of the study is to detect the presence and levels of mentioned signal molecules in saliva of patients with and without T2DM.