Can the Imbalance Between Neurotrophic and Apoptotic Proteins be the "Beware the Ides of March" for Unaffected Relatives of Schizophrenia Patients?

Abstract

Schizophrenia (SZ) is a mental disorder with a strong genetic basis as well as epigenetic aspects. Siblings of patients with SZ can share certain endophenotypes with the patients, suggesting that the siblings may be important for distinguishing between trait and state markers. In the current study, we aimed to characterize the balance between pro-BDNF/mature BDNF and its receptors p75NTR/TrkB, which is tpa-BDNF pathways proteins and thought to play a role in synaptic pruning as a possible endophenotype of schizophrenia. Forty drug-naïve patients with first-episode psychosis (FEP) matched for age, gender and level of education, 40 unaffected siblings (UAS) of patients with FEP and 67 healthy controls (HC) were included in the study. Blood samples were collected from all participants to determine BDNF, pro-BDNF, TrkB and p75NTR, PAI1, tPA, ACTH and cortisol levels. We showed that levels of proteins of the tPA-BDNF pathway, pro-BDNF/m-BDNF and p75NTR/TrkB ratios could successfully differentiateFEP and their siblings from the HCs by using ROC analysis. Plasma levels of m-BDNF were found to be the lowest in the healthy siblings and highest in the healthy control group with statistically significant differences between all 3 groups. The plasma levels of pro-BDNF in the healthy control group were similar to the FEP patients, the same in the healthy siblings of the FEP patients. Our data Support the hypothesis that imbalance between neurotrophic and apoptotic proteins might occur in SZ, and this imbalance could be an endophenotype of the disease.