Longitudinal Changes in Serum Interleukin-33 Levels During Acute Psychotic Relapse and Clinical Improvement in Schizophrenia: An Admission-Discharge Study.

Background/

Objectives

Schizophrenia pathophysiology has been linked to immune dysregulation, but the role of interleukin-33 (IL-33) during acute psychotic relapse remains insufficiently investigated. This exploratory admission-discharge study aimed to evaluate serum IL-33 levels in inpatients with paranoid schizophrenia and in healthy controls.

Methods

Serum IL-33 was measured at midday (12:00 h) and midnight (24:00 h) in 21 inpatients with paranoid schizophrenia and 21 age- and sex-matched healthy controls (HC). Patients were sampled at admission and discharge. HC underwent one sampling day, with blood collected at both 12:00 h and 24:00 h, during the interval between the patients' admission and discharge assessments. Psychopathology was assessed using the Positive and Negative Syndrome Scale (PANSS).

Results

PANSS positive and general psychopathology scores decreased from admission to discharge (p < 0.001 and p = 0.008, respectively). Serum IL-33 concentrations were descriptively higher in patients than in HC, but between-group differences were not statistically significant. Midnight serum IL-33 increased from admission to discharge (214.9 ± 358.0 vs. 241.2 ± 379.4 pg/mL; p = 0.028), whereas the midday change was nonsignificant. Age was inversely correlated with IL-33 in patients; associations with antipsychotic dosage and sex were not statistically significant.

Conclusions

The midnight increase in IL-33 accompanied clinical improvement, but medication, hospitalization, age, and smoking remain potential confounders. These exploratory findings warrant replication and do not establish IL-33 as a diagnostic or state biomarker.