Research Article For reprint orders, please contact: reprints@future-science.com Assessing a multiplex-targeted proteomics approach for the clinical diagnosis of periodontitis using saliva samples Brenda Mertens ‡ ,1 , Val´ erie Orti ‡ ,1 , J´ er ˆ ome Vialaret 2 , Philippe Gibert 1 , Aroa Rela ˜ no-Gin ´ es 2 , Sylvain Lehmann 2 , Dominique Deville de P ´ eri ` ere 2 & Christophe Hirtz *,2 1 U.F.R. d’Odontologie, D´ epartement de Parodontologie, 545, avenue du Professeur Jean-Louis Viala, 34 193 Montpellier, Cedex 5 2 University of Montpellier, LBPC - IRMB, CHU de Montpellier, 80 rue Augustin Fliche, 34 295 Montpellier, France * Author for correspondence: Tel.: +33 4 67 33 04 20; Fax: +33 4 67 33 69 21; christophe.hirtz@umontpellier.fr ‡ Authors contributed equally Aim: The present study focused on the research of new biomarkers based on the liquid chromatography- multiple-reaction monitoring (MRM) proteomic profle in whole saliva of patients with periodontitis compared with periodontal healthy patients. Methods: A 30-min multiplexed liquid chromatography- MRM method was used for absolute quantifcation of 35 plasma biomarkers in saliva from control pa- tients and patients with periodontitis. Results: Three proteins namely hemopexin, plasminogen and α- fbrinogen were shown to be clearly related to the presence of periodontitis compared with healthy pa- tients. Apolipoprotein H was found to discriminate for the frst time chronic and aggressive periodontitis. Conclusion: Our results indicate that this innovative MRM method could be used to screen for periodon- titis in clinical environment. Furthermore, apolipoprotein H was found to be a discriminant biomarker of aggressive periodontitis. First draft submitted: 30 September 2017; Accepted for publication: 7 November 2017; Published online: 15 December 2017 Keywords: clinical chemistry • mass spectrometry • oral pathology • periodontitis • proteomics • saliva biochemistry Proteomics methods are used increasingly in molecular medicine studies. Oral fluids based on whole-mouth saliva have been increasingly studied as an alternative to blood samples in proteomics over the last 10 years [1]. Noninvasive saliva collection procedures cause less patient anxiety than blood sampling while nevertheless providing a complex biological matrix containing thousands of proteins and peptides of endogenous (salivary glands) or exogeneous (plasma and bacteria) origins [2]. For example, this technology has already been successfully used to detect several disease-associated proteins or peptides in Sj¨ ogren’s syndrome [3] and for the diagnosis of systemic diseases [4] or cancer [5]. The strength of this technology is that it allows both quantitative and qualitative study of several proteomes in a range of conditions. Recently, a multiple-reaction monitoring (MRM) mass spectrometry (MS)- based quantitative proteomic workflow was developed to screen for plasma biomarkers in saliva based on 35 stable isotope-labeled standards (SIS) peptides [6]. Moreover, the technology was shown to be entirely compatible with clinical practice, in some cases replacing/supplementing clinical antibody-based assays. In this context, we applied this innovative approach to a common oral pathology for which clinical biomarkers are needed: periodontitis. Periodontitis, also known as gum disease or pyorrhea, is a bacteria-induced multifactorial inflammatory disease of the periodontium characterized by a complex host–microbial interaction [7]. Periodontitis involves progressive loss of the alveolar bone surrounding the teeth, and if left untreated can lead to loosening or loss of the teeth. Currently, periodontitis is diagnosed based on the results of a clinical and radiological examination interpreted according to the American Academy of Periodontology criteria [8]. The high prevalence of this disease and its impact on general health make it a real public health issue. Indeed, periodontal diseases have been linked to the increased prevalence and incidence of systemic diseases such as diabetes, cardiovascular diseases, stroke and rheumatoid arthritis [9–16]. Previous studies have shown that plasma biomarkers can be quantified in saliva from patients with periodontitis. For example, serum ceruloplasmin levels were shown to be increased in patients with periodontitis compared with Bioanalysis (Epub ahead of print) ISSN 1757-6180 10.4155/bio-2017-0218 C  2018 Future Science Ltd