Human herpesvirus 6 and cytomegalovirus in ileocolonic mucosa in inflammatory bowel disease

Abstract

Objectives: Reactivation of a latent cytomegalovirus (CMV) may occur in inflammatory bowel disease (IBD). Data of human herpesvirus 6 (HHV-6)--a close relative to CMV--in active IBD are scarce. The aim of this study was to detect HHV-6 and CMV antigens in the mucosa of active and inactive IBD.

Material and methods: 79 IBD patients (47 ulcerative colitis (UC) and 32 Crohn's disease (CD)) were recruited and endoscopic and histological disease activity was scored. Control group consisted of 15 non-IBD patients with normal colonoscopy. Immunohistochemical stainings for HHV-6B and CMV antigens were performed on biopsy specimens from the ileum and colorectum. The intensity of HHV-6B and CMV expression was graded as negative, mild, moderate, or intense.

Results: HHV-6B antigen was positive in 35 (44%) and CMV in 64 (81%). Of controls, 6 (40%) were mildly positive for HHV-6 and 6 (40%) for CMV. In IBD, both CMV and HHV-6B intensity correlated with endoscopic disease severity (CMV p = 0.010 and HHV-6 p = 0.048). Simultaneous HHV-6B and CMV antigen expression occurred in 29 (37%) and associated with endoscopic activity (p = 0.006) and to a number of immunosuppressives (p = 0.033). A significant difference in HHV-6B positivity was found between endoscopically active and inactive UC (p = 0.040). Both CMV and HHV-6B intensity correlated with histological severity in the rectal biopsy specimens (for CMV p = 0.040 and for HHV-6B p = 0.027).

Conclusions: Both viruses occurred ubiquitously in the IBD mucosa. Coexistence of viruses was common and associated with disease activity and use of immunosuppressives. HHV-6B intensity correlated with endoscopic severity in UC.