Morphological and laboratory cytokine indices in osteoarthritis patients demonstrated in the presence of human herpesvirus 7 infection

Osteoarthritis (OA) has long been suggested as a degenerative disease affecting joints. More recent studies demonstrate the contribution of inflammation to the development and progression of the disease. Furthermore, the inflammatory affection of the synovium is considered a powerful driver of the disease. Among arthritogenic viruses manifesting with synovial damage human herpesvirus 7 (HHV-7) remains very little studied. Therefore, we proposed several objectives when assessing synovitis in OA patients, determining the occurrence and distribution of the HHV-7 antigen within the synovial membrane of OA-affected subjects, and correlating plasma and tissue levels of common proinflammatory cytokines. Forty-eight OA patients presented with synovial materials obtained during joint replacement surgery were stratified into two groups: nineteen HHV-7 polymerase chain reaction (PCR)+ subjects (39.6%) and 29 HHV-7 PCR− subjects (60.4%). Synovitis was assessed by applying the Krenn scoring system. Synovial HHV-7, CD4, CD68, and TNF antigens were detected immunohistochemically, the plasma levels of TNF and IL6 measured by an enzyme-linked immunosorbent assay. Persistent HHV-7 infection was confirmed in 81.5% but reactivation in 20.5%; virus-specific DNA was found in 35.2% of synovial membrane tissue samples. No significant difference in the plasma levels for TNF or IL-6 was determined by comparison of the HHV-7 PCR+ and HHV-7 PCR− groups. Histopathologically, both study groups presented with low-grade synovitis. The number of synovial CD4- positive cells in the HHV-7 PCR+ group was significantly higher than that in the HHV-7 PCR‒ group. The number of TNF+ and HHV-7+ lymphocytes, as well as HHV-7+ vascular endothelial cells, was strongly correlated. The balance between virus latency and reactivation is a long-term relationship between the host and infectious agent, and the immune system appears to be involved in displaying overreaction when a shift in the established equilibrium develops.