The relationship between oxidative stress and psychotic disorders in 22q11.2 deletion syndrome

Background: 22q11.2 Deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans. This condition is associated with a wide range of symptoms including immune and neuropsychiatric disorders. Notably, psychotic disorders including schizophrenia have a prevalence of similar to 30%. A growing body of evidence indicates that neuroinflammation and oxidative stress (OS) play a role in the pathophysiology of schizophrenia. In this study, we aim to assess the interaction between 22q11.2DS, OS and schizophrenia. Methods: Blood samples were collected from 125 participants (including individuals with 22q11.2DS [n = 73] and healthy controls [n = 52]) from two sites: Sheba Medical Center in Israel, and University Hospital Gasthuisberg in Belgium. Baseline OS levels were evaluated by measuring Myeloperoxidase (MPO) activity. A subsample of the Israeli sample (n = 50) was further analyzed to examine survival of Peripheral Blood Mononuclear Cells (PBMCs) following induction of OS using vitamin K3. Results: The levels of MPO were significantly higher in all individuals with 22q11.2DS, compared to healthy controls (0.346 +/- 0.256 vs. 0.252 +/- 0.238, p =.004). In addition, when comparing to healthy controls, the PBMCs of individuals with 22q11.2DS were less resilient to induced OS, specifically the group diagnosed with psychotic disorder (0.233 +/- 0.206 for the 22q11.2DS individuals with psychotic disorders, 0.678 +/- 1.162 for the 22q11.2DS individuals without psychotic disorders, and 1.428 +/- 1.359 for the healthy controls, p =.003, eta(2) = 0.207). Conclusions: Our results suggest that dysregulation of OS mechanisms may play a role in the pathophysiology of the 22q11.2DS phenotype. The 22q11.2DS individuals with psychotic disorders were more sensitive to induction of OS, but did not present significantly different levels of OS at baseline. These results may be due to the effect of antipsychotic treatment administered to this sup-group. By elucidating novel molecular pathways, early identification of biochemical risk markers for 22q11.2DS and psychotic disorders can be detected. This can ultimately pave the way to the design of early and more precise interventions of individuals with 22q11.2DS.