IL-33, sST2, and CRP in Panic Disorder

Investigation of IL-33, sST2, and C-Reactive Protein in Panic Disorder: A Cross-Sectional Case-Control Study

Panic disorder (PD) is characterized by recurrent and unexpected panic attacks and is associated with significant functional impairment. Increasing evidence suggests involvement of immune-inflammatory mechanisms in PD. Elevated levels of inflammatory markers such as C-reactive protein (CRP) have been reported in PD; however, interleukin-33 (IL-33) and soluble suppressor tumorogenicity-2 (sST2), components of the IL-33/sST2 signaling axis, have not previously been investigated in PD. This cross-sectional case-control study aims to compare peripheral serum IL-33, sST2, and CRP levels between drug-naïve subjects diagnosed with PD and healthy controls (HCs). The findings may contribute to understanding the inflammatory mechanisms underlying PD.

This is an observational, cross-sectional, case-control study conducted at the psychiatry outpatient clinic of Elazığ Mental Health and Diseases Hospital. It was planned to include 40 participants in the panic disorder (PD) and healthy controls (HCs) groups. All participants will complete a sociodemographic data form and the DSM-5 Panic Disorder Severity Scale (Adult Form). Venous blood samples (5 mL) will be collected between 08:30-10:00 a.m. after 12-hour fasting. Serum interleukin-33 (IL-33), soluble suppressor tumorogenicity-2 (sST2), and C-reactive protein (CRP) levels will be measured using commercially available ELISA kits. Statistical analyses will include independent samples t-test or Mann-Whitney U test, chi-square test, correlation, regression, and ROC analysis. A p value < 0.05 will be considered statistically significant.

1. For Panic Disorder (PD) Group:

   *Inclusion Criteria:

   • Being between 18-65 years of age
   • Having a diagnosis of panic disorder (PD) according to DSM-5-TR and having presented to the hospital with panic attack symptoms of the disorder
   • Not having previously used any medication for psychiatric purposes (drug-naive)
   • Not having any additional active psychiatric disorders besides PD at the current presentation
   • Absence of hypertension, diabetes mellitus, renal failure, hepatic failure, neurological disease with cognitive impairment, acute infection, pregnancy, autoimmune disease, or cancer
   • Not having taken any medication or supplements in the last month
   • Completing sociodemographic and scale data fully
   • Volunteering to participate in the study

   For PD Group:

   *Exclusion Criteria:

   • Being outside the 18-65 age range

   • Not meeting the diagnostic criteria for PD according to DSM-5-TR or being in good health

   • Having a history of psychiatric medication use

   • Having an additional psychiatric disorder besides PD at the current application

   • Presence of hypertension, diabetes mellitus, renal failure, hepatic failure, neurological disease with cognitive impairment, acute infection, pregnancy, autoimmune disease, cancer

   • Patients with a body mass index (BMI) <18.5 kg/m² and >29.9 kg/m²

   • Taking any medication or supplement in the last month
   • Incomplete completion of sociodemographic and scale data
   • Not volunteering to participate in the study

2. For Healthy Control Group:

   • Inclusion Criteria:

     • Being between 18-65 years of age
     • Not having any active psychiatric disorder
     • Not having previously used any medication for psychiatric purposes (drug-naive)
     • Not having hypertension, diabetes mellitus, kidney failure, liver failure, neurological disease with cognitive impairment, acute infection, pregnancy, autoimmune disease, or cancer
     • Not having taken any medication or supplement in the last month
     • Completing sociodemographic and scale data fully
     • Volunteering to participate in the study

For Healthy Control Group:

*Exclusion Criteria:

• Being outside the 18-65 age range
• Having any active psychiatric disorder
• Having a history of using psychiatric medication
• Having hypertension, diabetes mellitus, renal failure, hepatic failure, neurological disease with cognitive impairment, acute infection, pregnancy, autoimmune disease, or cancer
• Patients with a body mass index (BMI) < 18.5 kg/m² and > 29.9 kg/m²
• Taking any medication or supplement in the last month
• Incomplete completion of sociodemographic and scale data
• Not volunteering to participate in the study