Salivary kallikrein-8 as a favorable biomarker for stress response

Abstract

Background/Aim. Kallikreins (KLKs) are a group of serine protease enzymes capable of cleaving protein peptide bonds. Besides, they are proteolytic enzymes that mediate the conversion of kininogen (alpha 2-globulin) to brady-kinin or kallidin. The aim of the study was to examine whether KLK8 might serve as a novel stress biomarker. Methods. Twenty-four students (17 female and 7 male) were included in the study. The general and dental health of the students were evaluated in the appropriate anamnesis format. Unstimulated samples were collected by Sarstedt? saliva collection tubes as recommended: 08.00?09.00 am, 12.00, and 2.00?3.00 pm on the exam day. KLK levels were measured by a KLK8 Human ELISA kit. Results. The salivary KLK8 levels in the morning (1.25 ? 0.26 pg/mL) were statistically significantly lower than the KLK8 levels pre-exam [at 12.00 (2.89 ? 0.85 pg/mL)] (p = 0.0006). There was also a significant difference in salivary KLK8 levels between pre- and post-exam (1.69 ? 0.39) time points (p = 0.0005). Conclusion. These results show that the differences in salivary KLK8 levels might be related to the degree of stress, indicating that KLK8 may serve as a novel stress biomarker.