Individuals with schizophrenia were shown to have altered antibody plasma concentrations against protein fragments of schizophrenia-correlated genes, and increased plasma concentrations of anti-TRANK1 immunoglobin G (IgG) may serve as a biomarker for the disease, according to a recent study published in Schizophrenia Bulletin.
Archived plasma samples from patients with schizophrenia (n=169) were used to evaluate circulating antibodies targeting the peptides of schizophrenia-correlated genes. Antigen levels were evaluated using an enzyme-linked immunosorbent assay and compared with control samples from patients without schizophrenia (n=187).
Among the 18 antigens tested in samples from patients with schizophrenia, 6 antigens showed increased plasma levels (DPYD, MAD1L1, ZNF804A, DRD2, TRANK1, and MMP16), and 3 showed decreased plasma levels (TSNARE1, TCF4, and VRK2) when compared with those from controls. Furthermore, anti-TRANK1 antigens showed a sensitivity of 20.7% and a specificity of 95.2%, suggesting the potential for future use as a biomarker of the condition for some populations. When the effects of antipsychotic treatments were evaluated, risperidone was shown to reduce overall antibody levels in the plasma, but it did not have an effect on anti-TRANK1 IgG.
The study investigators wrote, “Patients with schizophrenia had significant changes in circulating levels of IgG antibodies against peptide antigens encoded by schizophrenia-associated genes.” They also noted the importance risperidone being the only antipsychotic drug affecting antibody levels in plasma, suggesting, “that its antipsychotic effect may partially depend on a regulatory process of the immune system”.
Whelan R, St Clair D, Mustard C, Hallford P, Wei J. Study of novel autoantibodies in schizophrenia [published online January 24, 2018]. Schizophr Bull. doi:10.1093/schbul/sbx175