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Periodontitis is characterized by the loss of the supporting tissues of the teeth in an inflammatory-infectious context. The diagnosis relies on clinical and X-ray examination. Unfortunately, clinical signs of tissue destruction occur late in the disease progression. Therefore, it is mandatory to identify reliable biomarkers to facilitate a better and earlier management of this disease. To this end, saliva represents a promising fluid for identification of biomarkers as metabolomic fingerprints. The present study used high-resolution 1H-nuclear magnetic resonance (NMR) spectroscopy coupled with multivariate statistical analysis to identify the metabolic signature of active periodontitis. The metabolome of stimulated saliva of 26 patients with generalized periodontitis (18 chronic and 8 aggressive) was compared to that of 25 healthy controls. Principal Components Analysis (PCA), performed with clinical variables, indicated that the patient population was homogeneous, demonstrating a strong correlation between the clinical and the radiological variables used to assess the loss of periodontal tissues and criteria of active disease. Orthogonal Projection to Latent Structure (OPLS) analysis showed that patients with periodontitis can be discriminated from controls on the basis of metabolite concentrations in saliva with satisfactory explained variance (R2X = 0.81 and R2Y = 0.61) and predictability (Q2Y = 0.49, CV-AUROC = 0.94). Interestingly, this discrimination was irrespective of the type of generalized periodontitis, i.e. chronic or aggressive. Among the main discriminating metabolites were short chain fatty acids as butyrate, observed in higher concentrations, and lactate, γ-amino-butyrate, methanol, and threonine observed in lower concentrations in periodontitis. The association of lactate, GABA, and butyrate to generate an aggregated variable reached the best positive predictive value for diagnosis of periodontitis. In conclusion, this pilot study showed that 1H-NMR spectroscopy analysis of saliva could differentiate patients with periodontitis from controls. Therefore, this simple, robust, non-invasive method, may offer a significant help for early diagnosis and follow-up of periodontitis.

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Short-term studies have shown that histamine is involved, via its H 2 receptors (H 2 R), in the mediator network regulating trabecular bone loss in long bones of ovariectomized (OVX) rats. It is not known whether this effect of histamine persists over time or involves other skeletal sites. In this study, rats were maintained for 6 months postOVX and treated daily with saline or famotidine (10 mg kg −1 ), an H 2 R antagonist. At the end of the experimental period, femur trabecular bone mass was markedly decreased in OVX rats, whether or not they were treated with famotidine. In contrast, in the fourth lumbar vertebra, where bone loss starts later than in the femur, famotidine treatment attenuated the decline in trabecular bone volume, protected the trabecular architecture, maintained the thickness of the cortices and reduced the numbers of osteoclasts and tartrate-resistant acid phosphatase-positive preosteoclasts, whereas it had no influence on bone formation parameters. In vertebral bone marrow of OVX rats, the numbers of mast cells (MCs) and non-MC histamine-producing cells increased, while famotidine treatment significantly diminished both cell populations. These data show that H 2 R antagonism does not protect trabecular bone mass in the long term, and that short-term protection involves all bones. Histamine is involved during the early phase of strong osteoclastic resorption but not during the late phase of slower resorption, suggesting that different mediator networks control the two phases of destruction. Histamine would be part of the network mediating the early phase.