Weak cation exchange magnetic beads coupled with MALDI-TOF-MS in screening serum markers in perimenopausal women with osteopenia

The present study aimed at investigating the weak cation magnetic separation technology and matrixassisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) in screening serum protein markers of osteopenia from 10 perimenopausal women with normal bone mass and 10 perimenopausal women without osteopenia as control group, to find a new method for screening biomarkers and establishing a diagnostic model for primary type I osteoporosis. Serum samples were collected from perimenopausal women with osteopenia and perimenopausal women with normal bone mass. Protein was extracted from serum samples with the sample preparation tool of weak cation exchange magnetic beads (MB-WCX) technology, and mass spectra acquisition was done by MALDI-TOF-MS. The visualization and comparison of large data sets, statistical peak evaluation, model recognition, and discovery of biomarker candidates were handled by the proteinchip data analysis system software (ZJU-PDAS). The diagnostic models were established using genetic arithmetic (GA) based support vector machine (SVM). The SVM result with the highest Youden Index was selected as the model. Combinatorial Peaks having the highest accuracy in distinguishing different samples was selected as potential biomarker. From the two group serum samples, a total of 134 differential protein peaks were selected. 10 protein peaks with significant intensity differences were screened. In the pair-wise comparisons, processing of MALDI-TOF spectra resulted in the identification of 10 differential protein peaks between perimenopausal women with osteopenia and perimenopausal women with normal bone mass. The difference of protein peaks by Youden index showed that the highest protein peaks had a mass to charge ratio of 8162 and 5921 Da. A diagnosis model was established with these two peaks as the candidate marker, and the model specificity of the model is 100%, the sensitivity was 100% by leave-one-out cross validation test. The two groups of specimens in support vector machine results on the scatterplot could be clearly distinguished. The four peaks in the SVM model were identified as Proteinkish-B and C-X-C motif chemokine 6 by TagIdent tool. This study is novel as it provides a new serological method for discovering serum protein markers to screen and diagnose osteopenia. This will help the clinicians preventing and treating primary type I osteoporosis.