Background and Aims

Incidence of autoimmune thyroiditis (AIT) dramatically arises with time worldwide. Some studies bring evidences of human herpesvirus-6 (HHV-6) involvement in AIT development. HHV- 6 has two genes (U12 and U51) that encode putative homologs of cellular G-protein-coupled receptors (GPCR). It was shown in vitro that these viral GPCRs could interact with cytokine signalling pathways down-regulating RANTES.

Aim of this study was to investigate HHV-6 involvement in AIT development through interactions with RANTES signaling pathways.

Methods

Blood samples were collected from 110 patients (8 males and 102 females) with autoimmune thyroiditis following thyroidectomy. The control group included 30 healthy blood donors (25 females and 5 males). Commercial kits for suspension multiplex immunological assays were used to detect RANTES, INF-γ, IL-6 and TNFα levels in blood plasma.

Results

Data from previous studies showed that 98% of AIT patients’ samples are positive for HHV-6 genome sequence. RANTES median level was found to be significantly lower in AIT patients than in control group's plasma samples (150.3 [IQR: 71.6-418.2] vs 1359 [IQR: 844.2-2596.0] pg/ml; p<0.0001). However, INF-γ and TNFα median levels were found to be significantly higher in patients' samples.

Conclusions

Significant difference of RANTES and two pro-inflammatory cytokine levels in AIT patients’ samples may point to the role of RANTES levels in AIT development. In addition, data from prior studies showed that 43% of AIT patients with low RANTES levels were positive on HHV-6 U12/U51 mRNA in thyroid gland tissue samples, which brings evidences of possible HHV-6 GPCR involvement in RANTES signaling pathway modulation.