Activation of the Immune-Inflammatory Response System and the Compensatory Immune-Regulatory Reflex System in Antipsychotic Naive First Episode Psychosis

Background: First episode psychosis (FEP), schizophrenia and affective disorders are accompanied by activation of the immune inflammatory response system (IRS). The compensatory immune-regulatory reflex system (CIRS) is a regulatory immune response that is induced by the IRS but exerts negative feedback through, for example, increased levels of anti-inflammatory cytokines such as IL-4, IL-13 and IL-10. Different phenotypes of schizophrenia may exhibit distinct IRS and CIRS immune profiles.Aims: This study aims to examine the IRS and CIRS components, including macrophagic M1, T-helper (Th)-1, Th-2, Th-17 and T-regulatory (Treg) phenotypes, in antipsychotic-naïve FEP patients before and after risperidone treatment.Methods: We included 31 antipsychotic-naïve FEP patients who had measurements of IRS and CIRS biomarkers before and after treatment with risperidone for 10 weeks, and 22 healthy controls.Results: Antipsychotic-naive FEP patients showed interrelated increments in M1, Th-1, Th-2, Th-17 and Treg phenotypes and a relatively greater IRS response (especially granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-6 and IL-12) as compared with the CIRS response (IL-4, IL-13, IL-5 and IL-10). Inflammatory markers, especially IL-6 and IL-8, were significantly correlated with negative, psychotic, affective and excitation symptom dimensions. Treatment with risperidone significantly suppressed the IRS and CIRS. Baseline levels of CIRS biomarkers, especially higher soluble tumor necrosis factor receptor-1 and IL-10 predicted clinical improvement during treatment.Discussion: Our findings indicate that FEP is characterized by robust IRS (M1 + Th-1 + Th-17) and CIRS responses, suggesting that monocytes, macrophages, Th-1, Th-2, Th-17 and Treg cells are activated. The findings indicate that a) FEP patients are prone to the detrimental effects of M1, Th-1, Th-17 and Th-2 cells, which may contribute to long-lasting abnormalities in brain circuitry; and b) in FEP, the CIRS may contribute to recovery from the acute phase of illness. Enhancing the CIRS is a new drug target to treat FEP.