Detection of Salivary Biomarkers in Morbid Obesity by Proteomic Analysis

Backgroud: Morbid obesity (body mass index [BMI] ≥ 40 kg/m²) is a risk factor for several chronic health conditions as well as being associated with increased mortality. Interest in saliva as a diagnostic tool for monitoring general health and for early diagnosis of disease has increased in the last few years. Surface-enhanced laser desorption/ionization time-of-flight-mass spectrometry (SELDI-TOF-MS) is a novel high throughput and extremely sensitive proteomic approach that allows protein expression profiling of large sets of complex biological samples. Objectives: In this study, the salivary protein profile of morbid obese patients was compared with control subjects. The aims were (a) to identify salivary biomarkers of morbid obesity, (b) to establish the inflammatory profile of the obese patients. Methods: Stimulated saliva were collected in two groups of subjects, one of 42 obese patients scheduled for gastric bypass surgery (BMI = 46.2 ± 13.1) and the other of 26 non-obeses control subjects (BMI = 21.5 ± 2.1). The saliva samples were centrifugated at 10 000 g for 15 min at 4°C and then stored at – 80°C. Peptid and protein expression profiles for each sample were generated by SELDI-TOF-MS using four chip surface types with different chemical properties: Q10, CM10, H50 and IMAC-Cu. Mean peak intensities of obese patients and non-obese subjects were compared by univariate analyses. Results: SELDI-TOF-MS of 1-100 kDa peaks revealed peaks with changes in the obese group that differed from the control group at p < 0.05. In particular, peak of 3374 m/z was increased, while 5378 m/z and 15550 m/z peaks were decreased in morbid obese samples. Conclusions: The saliva proteomic profile of morbid obesity is a mixture of increased and decreased proteins when compared with normal BMI subjects. The work continues by electrophoresis procedures to identify which proteins are modified in morbid obese patients.