Clinical Significance of Serum Cytokine Levels in Patients Hospitalized for Active Inflammatory Bowel Diseases

Abstract

Introduction: Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory bowel diseases (IBD) of unknown cause. We aimed to investigate the clinical significance of serum cytokine levels in patients hospitalized for active CD or UC. Methods: Serum cytokine levels were measured in 13 CD patients and 19 UC patients before and after corticosteroids or anti TNF-α therapy during hospitalization. Thirty-two subjects were enrolled as a healthy control (HC) for comparison. Pre-treatment blood samples were collected on the day of hospitalization before the initiation of corticosteroids or anti TNF-α therapy. Post-treatment blood samples were collected on the 7th day after beginning corticosteroids or anti TNF-α therapy. Serum cytokine levels were compared between IBD patients and HC. Comparison was also performed between pre- and post-treatment phase. Results: Relapse of IBD within 1 year was observed in 27.3% of CD and 31.6% of UC patients. Interleukin-6 (IL-6) and TNF-α levels were significantly elevated in CD patients during pre-treatment active (P< 0.001, both) and post-treatment phase (P< 0.001, P=0.001) compared with HC. Similar results were observed in UC patients during pre-treatment active (P< 0.001, both) and post-treatment phase (P< 0.001, both) compared with HC. IL-6 and TNF-α levels significantly decreased in post-treatment CD patients compared with pre-treatment active phase (P=0.001, P=0.009). Similar results were found in post-treatment UC patients compared with pre-treatment active phase (P=0.001, P=0.022). Among preand post-treatment serum cytokine levels, only post-treatment serum IL-6 level was significantly associated with relapse of UC within 1 year (P=0.012). Conclusion: Elevated post-treatment serum IL-6 level was significantly associated with relapse of UC within 1 year. IL-6 and TNF-α levels were significantly elevated in pre- and post-treatment IBD patients compared with HC. Post-treatment IL-6 and TNF-α levels significantly decreased compared with pretreatment levels. IL-6 and TNF-α may act as a potential biomarker of diagnosing active disease, assessing therapeutic response, and predicting relapse in IBD patients.