Exploring salivary and gingival metabolomes for periodontitis biomarkers using nuclear magnetic resonance spectroscopy: A pilot study

Objectives: To investigate and correlate salivary and gingival tissue metabolomic profiles in periodontitis patients and healthy controls using proton nuclear magnetic resonance (¹H NMR) spectroscopy. Methods: Forty participants were enrolled, including 20 Stage II/III Grade B periodontitis patients and 20 healthy controls. Saliva and 2×2 mm gingival tissue samples were collected and analyzed using 700 MHz NMR spectroscopy. Data were processed using univariate ROC analysis, partial least squares discriminant analysis (PLS-DA), and variable importance in projection (VIP) scores through MetaboAnalyst 6.0. Results: Salivary samples from periodontitis patients showed elevated alanine, lactate, butyrate, pyruvate, glycine, valine, proline, acetate, taurine, GABA, succinate, and trimethylamine. Gingival tissue samples exhibited increased glycine, proline, glutamate, glutamine, valine, pyruvate, glycerophosphocholine, and taurine. Glycine, proline, valine, and taurine were consistently altered in both sample types. Metabolic pathway analysis indicated involvement of amino acid metabolism, microbial fermentation, and energy metabolism. Conclusions: NMR-based metabolomics effectively identifies site-specific and systemic metabolic alterations in periodontitis. Glycine, proline, valine, and taurine demonstrate potential as diagnostic biomarkers for periodontal disease.