Is There a Link between Human Herpesvirus Infection and Toll-like Receptors in the Pathogenesis of Pityriasis Rosea? A Case-control Study.

Human herpesvirus (HHV) 6 and 7 are involved in the pathogenesis of pityriasis rosea (PR). Our aim was to evaluate the role of the innate immune response in PR through the detection of Toll-like receptors (TLR) 2, 3, 4, 7, 8, and 9 expression in the skin of affected patients and to detect the possibility of being induced by HHV-6 and/or HHV-7 viral coexistence in these patients. Twenty-four patients with PR and 24 healthy controls were included in this case-control study. Biopsy was obtained from the PR lesion and from the healthy skin of controls for detection of HHV-6 and 7 as well as TLRs 2, 3, 4, 7, 8, and 9 gene expression using real-time polymerase chain reaction (PCR). Significantly elevated expression of all studied TLRs and significantly higher viral load of HHV-6 and 7 in PR cases were detected. A significant higher expression of TLR2 and 4 in HHV-7 positive cases and a significant positive correlation between TLR9 and HHV-7 viral load were documented. HHV6 and 7 may also be involved in the pathogenesis of PR via TLR pathways.