A group from Finland’s Helsinki University Hospital has published preliminary evidence to suggest HHV-6B may be involved in the development of adenomatous gastrointestinal polyps. In a series of immunocompetent patients with adenomas, polyp HHV-6B antigen expression from mucosal biopsies was more intense than in biopsies taken from patients receiving immunosuppressive drugs because of kidney transplantation or inflammatory bowel disease. In the study, HHV-6B and cytomegalovirus (CMV) antigen expression was determined from mucosal biopsy samples, and HHV-6-DNA content was investigated in adenomatous polyps (seven tubular adenomas and one tubulovillous adenoma) taken from eight immunocompetent patients and in three mucosal biopsy samples taken from immunocompetent patients without adenomas.
HHV-6B antigen expression (determined via immunohistochemistry) on mucosal biopsies was found to be strongly positive in five of eight patients with adenomas and negative in all patients without adenoma. In addition, HHV-6 DNA was detected (via in-situ hybridization) in seven of the eight adenomatous polyps, most intensely in the tubulovillous adenoma, and negative in all three mucosal biopsies of patients without adenoma. CMV antigen expression on mucosal biopsies was faintly positive in three of the adenoma patients.
It is known that HHV-6B antigens are commonly found in the intestinal mucosa of patients with immunosuppression, and a study published earlier this year reported that the activation of HHV-6B and HHV-7 in patients with gastrointestinal cancer may lead to a marked decrease in lymphocytes and worsening of immunosuppression (Sultanova 2013). The current study suggests further that HHV-6B may be significantly involved in GI pathogenesis, and the authors suggest that additional studies on involvement of HHV-6 in the development of gastrointestinal polyps are warranted.
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