Analysis of human endogenous retrovirus K and W expression and gait parameters in patients with rheumatoid arthritis

Background Human Endogenous Retroviruses (HERVs) compose about 8% of the genome. Although mostly silenced, they can be activated and may contribute to autoimmune diseases such as rheumatoid arthritis (RA). However, it is unclear whether HERV expression influences gait patterns in RA.Objective To assess HERV-W and HERV-K expression levels and their relationship with gait parameters in RA patients.Methods Cross-sectional case-control study with 32 participants (22 RA patients, 10 controls). Blood samples were analyzed for HERV-W and HERV-K expression using RT-PCR (−2-ΔΔCt). Gait analysis was conducted on a pressure platform during a 20-m walk at a self-selected pace.Results HERV-W expression was four times higher in RA patients (p < 0.01), while HERV-K expression was twice as high (p < 0.01). RA patients showed impaired gait, including reduced forefoot contact area (p < 0.01) and lower peak pressure across all foot regions. No correlation was found between HERV expression and gait parameters.Conclusion RA patients exhibit elevated HERV-W and HERV-K expression, with greater increase in HERV-W. Despite clear gait impairments, HERV levels did not correlate with gait patterns in remission status of the disease and the clinical control. Further studies are needed to clarify the clinical role of HERVs in RA.