Relationship between human herpesvirus 6 infection and inflammatory bowel disease using novel biomarker

OBJECTIVE: Inflammatory bowel disease (IBD) is closely related to stress and fatigue. Human herpesvirus 6B (HHV‐6B) is reactivated by stress and fatigue and is associated with IBD. This study aimed to clarify the relationship between IBD and HHV‐6B. METHODS: Antibody titers to SITH‐1, a protein specific to HHV‐6B latent infection, were measured in 163 patients with IBD (107 with ulcerative colitis [UC] and 56 with Crohn's disease [CD]); clinical and endoscopic scores and depression scores of UC and CD were analyzed to examine the relationship between SITH‐1 and IBD. The SITH‐1 cut‐off value was set as 1.96, according to known reports. RESULTS: In patients with UC, C‐reactive protein (CRP) level was significantly higher (1.5 vs 0.6 mg/L, P = 0.006) and disease exacerbation within 6 months after entry was significantly more common in the SITH‐1 (+) group (20% vs 0%, P < 0.001). In the subanalysis comparing with and without UC exacerbation, the optimal cut‐off value for SITH‐1 to detect UC exacerbation was 3.44 (area under the curve: 0.81; 95% confidence interval: 0.72–0.90). CRP levels, SITH‐1 levels, and disease activity scores by the clinical or endoscopic index were significantly higher in the exacerbation group than in the non‐exacerbation group (2.6 vs 0.9 mg/L, P = 0.03; 4.90 vs 1.71, P < 0.001; 4 vs 3, P = 0.03; 5 vs 3, P = 0.02; respectively). CONCLUSION: Patients with UC with high titers of SITH‐1 have high disease activity and frequent disease exacerbation. SITH‐1 can be associated with UC disease activity.