Deficient Serum Levels of IL-10 and IL-37 in Treatment-Naïve Ulcerative Colitis: Diagnostic and Severity Biomarkers

Author(s): Ali Nazar Hamid1, Israa Abdulwahid Dheeb2
Date: 08/10/2026
doi: https://doi.org/10.5281/zenodo.8425890

Abstract

Background: Ulcerative colitis (UC) is a chronic inflammatory disease characterized by abnormal 
immune responses in colonic tissues. Anti-inflammatory cytokines, such as IL-10 and IL-37, are critical 
regulators of intestinal immune homeostasis. However, their expression levels and their value as 
diagnostic markers in treatment-naive UC patients are still poorly understood, with limited data available 
from Middle Eastern countries. The study aims to evaluate IL-10 and IL-37 levels in sera as non-invasive 
biomarkers for UC diagnosis and disease severity.  
Methods: This prospective case-control study recruited 40 treatment-naive UC patients and 40 healthy 
controls from Al-Diwaniyah Teaching Hospital, Iraq, from October 2025 to April 2026. Sera from UC 
patients and healthy controls were examined for IL-10 and IL-37 levels using enzyme-linked 
immunosorbent assay (ELISA). For assessing the severity of the disease, Endoscopic Mayo Sub-score 
was used. For assessing the diagnostic performance, Receiver Operating Characteristic curve analysis was 
used, and correlation analysis was used to see the relationship between cytokines and disease parameters.                                                                          
Results: Significantly lower serum levels of interleukin-10 (IL-10) were found in patients with UC 
compared with healthy controls (8.33 ± 1.14 pg/mL vs. 12.31 ± 1.08 pg/mL; P = 0.001), representing a 
32% decrease. Similarly, interleukin-37 (IL-37) levels were also found to be lower in patients with UC 
(24.79 ± 5.23 pg/mL) than healthy controls (40.90 ± 5.07 pg/mL; P = 0.001), representing a 39% decrease. 
ROC curve analysis for IL-10 showed an area under the curve (AUC) of 0.996 (95% CI, 0.988 to 1.000) 
with 95.0% sensitivity and 97.5% specificity for a cutoff < 10.47 pg/mL, while ROC curve analysis for 
IL-37 showed an area under the curve (AUC) of 0.973 (95% CI, 0.945 to 1.000) with 92.5% sensitivity 
and 95.0% specificity for a cutoff < 34.71 pg/mL. IL-10 levels were inversely correlated with endoscopic 
severity of disease (mild, 10.23 ± 1.4; moderate, 8.21 ± 1.3; severe, 7.69 ± 1.1 pg/mL; P < 0.001), but 
there was no correlation with severity (P = 0.668) for IL-37. 

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