A distinct serum protein pattern in patients with paranoid schizophrenia

Introduction: Schizophrenia is a chronic mental illness, whose aetiology is still unclear; therefore, information about differences in serum protein patterns may improve the understanding of the pathophysiology of schizophrenia. The goal of this study was to use the proteomic approach to identify altered protein levels in the serum samples from patients with schizophrenia. Methods: Blood was collected from 10 patients with paranoid schizophrenia and 10 healthy volunteers matched by sex and age. Serum proteins were isolated by 2D gel electrophoresis. Proteins with altered levels were identified by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry. Results: We uncovered major changes in the expression of such proteins as apolipoproteins of classes A4 and C3, transthyretin (TTR) and serum amyloid A1. An increase in expression was found only for apolipoprotein A4, whereas the expression of apolipoprotein C3, TTR and serum amyloid A1 was decreased. The observed differences in the expression of serum proteins (TTR and serum amyloid) are in good agreement with the results obtained by other research groups during analyses of cerebrospinal fluid or post-mortem brain tissues by other methods. Conclusion: Such alterations of the expression of these proteins may indicate problems with regulation, for example, in the synthesis. On the other hand, the altered protein expression may simply reflect the pathophysiological status of patients, where these proteins could be candidates for biomarkers. Further research is needed to confirm the significance of the altered levels of these proteins in the pathogenesis of schizophrenia and to determine their suitability as biomarkers of schizophrenia.