CYSTATIN SN AS AN INNOVATIVE SALIVARY BIOMARKER FOR PERIODONTITIS: A CONTROLLED PILOT STUDY

Introduction: Periodontitis constitutes a significant health burden, impacting over one billion individuals worldwide. Unfortunately, this condition is characterized by irreversible damages to the tooth-supporting tissues, even from its initial manifestations. Consequently the necessity for early diagnosis, preceding the appearance of initial symptoms, becomes crucial. In this context, there is a growing recognition of saliva as a valuable tool for liquid biopsy, as it provides a non-invasive means to detect and monitor oral health conditions through the identification of biomarkers. In this regard, the present study aims at the identification of an innovative salivary biomarker whose expression correlates with the oral tissues’ health status in the context of periodontitis. Materials and Methods: In this study, a total of forty-five systemically healthy, non-smoker participants were consecutively recruited. The participants were categorized into three groups based on their oral health status: periodontally healthy conditions (H), severe periodontitis (P), and individuals with a reduction in periodontal tissue subsequent to periodontal treatment (T). Each group consisted of 15 participants. We applied twodimensional gel electrophoresis followed by MALDI-TOF-MS to compare the salivary proteome of healthy individuals to that of patients with untreated and treated periodontitis. Subsequently, the obtained data were validated by Western Blot analysis. Results: The salivary proteome of patients with untreated periodontitis showed a marked downregulation in the expression of Cystatin SN compared to the healthy ones; interestingly salivary expression of Cystatin SN is restored in patients who underwent the periodontal treatment. Western blot analysis confirmed the distinctive pattern of Cystatin SN expression observed through the proteomic approach. Discussion: Cystatin SN is considered one of the most important salivary protease inhibitors therefore its reduction might trigger a higher protease activity in oral tissues leading to the canonical symptoms of the disease. Although our study is preliminary, we can speculate that Cystatin SN might be used as a potential biomarker of periodontitis. The discovery of an innovative salivary biomarker capable of monitoring the periodontal health status can address the unmet clinical needs associated with early diagnosis and therapy management of periodontitis, ultimately leading to improved patient outcomes. Consequently, further investigations should be conducted in order to clarify the molecular process that drives the changes in the salivary expression of Cystatin SN within periodontal diseases.