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.

Key Words::

• Crohn's disease
• CMV
• HHV-6
• IBD
• ulcerative colitis

Acknowledgements

We thank laboratory technician Marjatta Palovaara and research nurse Pirkko Tuukkala for technical assistance. This study was supported by grants from the Mary and Georg C Ehrnrooth Foundation and the Helsinki University Central Hospital Research Fund (EVO grant).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.