Inflammatory Cytokine-Producing Cells and Inflammation Markers in the Synovium of Osteoarthritis Patients Evidenced in Human Herpesvirus 7 Infection.

Valerija Groma,Modra Murovska,Sofija Semenistaja,Simons Svirskis,Sandra Skuja,Mihails Tarasovs,Zaiga Nora-Krukle

doi:10.3390/ijms21176004

Valerija Groma, Modra Murovska + Show 5 more

Open Access

https://doi.org/10.3390/ijms21176004

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Abstract

A direct association between joint inflammation and the progression of osteoarthritis (OA) has been proposed, and synovitis is considered a powerful driver of the disease. Among infections implicated in the development of joint disease, human herpesvirus 7 (HHV-7) infection remains poorly characterized. Therefore, we assessed synovitis in OA patients; determined the occurrence and distribution of the HHV-7 antigen within the synovial membrane of OA-affected subjects; and correlated plasma levels of the pro-inflammatory cytokines tumor necrosis factor (TNF), interleukin-6 (IL-6), and TNF expressed locally within lesioned synovial tissues with HHV-7 observations, suggesting differences in persistent latent and active infection. Synovial HHV-7, CD4, CD68, and TNF antigens were detected immunohistochemically. The plasma levels of TNF and IL-6 were measured by an enzyme-linked immunosorbent assay. Our findings confirm the presence of persistent HHV-7 infection in 81.5% and reactivation in 20.5% of patients. In 35.2% of patients, virus-specific DNA was extracted from synovial membrane tissue samples. We evidenced the absence of histopathologically detectable synovitis and low-grade changes in the majority of OA patients enrolled in the study, in both HHV-7 PCR+ and HHV-7 PCR‒ groups. The number of synovial CD4-positive cells in the HHV-7 polymerase chain reaction (PCR)+ group was significantly higher than that in the HHV-7 PCR‒ group. CD4- and CD68-positive cells were differently distributed in both HHV-7 PCR+ and HHV-7 PCR‒ groups, as well as in latent and active HHV-7 infection. The number of TNF+ and HHV-7+ lymphocytes, as well as HHV-7+ vascular endothelial cells, was strongly correlated. Vascular endothelial cells, especially in the case of infection reactivation, appeared vulnerable. 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.

Highlights

Joint diseases are recognized as common, widespread disabling pathologies all over the globe [1]
Qualitative nested polymerase chain reaction (PCR) testing was performed on 54 patients
The action of an inflamed synovium as a trigger of the OA process has been suggested and points at cells recruited in intra-articular changes [36]

Summary

Introduction

Joint diseases are recognized as common, widespread disabling pathologies all over the globe [1]. Among chronic rheumatic diseases having a substantial impact on population health, osteoarthritis (OA) is the one destined to increase and become the most prevalent [2]. Previous studies have accentuated the role of OA as the major cause of hip and knee replacement surgeries [4]. Osteoarthritis has long been viewed as a degenerative disease of cartilage, but accumulating evidence indicates that inflammation has a crucial role in its pathogenesis [5,6]. A direct association between joint inflammation and the progression of OA has been proposed [7,8], and synovitis has been considered a powerful driver of the OA process [9]

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