Search for viral nucleic sequences in rheumatoid cells

Retroviral sequences in rheumatoid arthritis synovium

There are several relationships between retroviruses and cellular transformation, as well as retroviruses being involved in the development of autoimmune diseases. Retroviruses have been discussed as etiologic agents modulating or triggering certain pathways in the pathogenesis of rheumatoid arthritis (RA). However, none of the currently known retroviruses has been identified as specific for RA. Due to the unique properties of retroviruses, distinct experimental approaches can be used to detect retroviral activity in cells and tissues. Current research in RA using state-of-the-art molecular biology techniques includes both the search for exogenous and endogenous retroviral gene sequences in synovium of patients with RA.

Retroviruses and chronic arthritis. Possible significance of some recent observations

Retroviruses have been proposed as etiologic agents for the development of chronic arthritis in humans. The arthritis seen in goats infected by caprine arthritis encephalitis virus and the spontaneous arthritis of inbred MRL/l mice illustrate how retroviruses may cause the development of a disorder closely resembling human rheumatoid arthritis. Several investigators have searched for evidence of retrovirus infection in patients with chronic arthritis, but in most cases the results have been disappointing. However, in 1983, Iversen isolated a virus-like particle from a patient with psoriasis. The particle had a buoyant density in sucrose and a protein composition that closely resembled murine and primate retroviruses. Particle proteins participate in immune complex formation in psoriasis, in psoriatic arthritis, and in ankylosing spondylitis. Particle proteins are also present in deposits in psoriatic lesions and in affected synovial tissue resembling immune complex deposits. The possible role for retrovirus-like antigens in the inflammatory process in psoriasis and seronegative arthritis is discussed.

Etiology of rheumatoid arthritis

Definite genetic associations with immunological cooperative HLA-D(R) antigens have been demonstrated for rheumatoid arthritis (RA). Microbial etiology has not been proven, but some hope for the supporters of this view is still given by small viruses, plasmids of enteric bacteria or perhaps oncogen-like DNA-sequences. Yet, electrophoretical analysis of membrane proteins or surface glycoproteins of RA synovial cells does not show any differences compared to reference cells. Autoimmunity to several tissue elements has been demonstrated, but most of it is of secondary nature. Antigenicities of type II and III collagens are probably only contributory factors for HLA-DR4 positive individuals. Proteoglycans or minor cartilage collagens have not been extensively studied, so far. Endocrine, dietary or psychological influences might be triggering events for otherwise 'preloaded' individuals.

Plasma membrane glycoproteins of cultured rheumatoid synovial fibroblasts

Fibroblast cultures were started from synovial tissue samples of 12 rheumatoid arthritic, 9 non-rheumatoid synovitic and 6 control patients. External galactose units of plasma membrane glycoproteins of confluent cells were labelled using the galactose oxidase-tritiated borohydride method. These surface-labelled cells were analyzed for possible differences in their glycoproteins by electrophoresis in SDS-containing polyacrylamide gradient gels. Total cell lysates were separated into 50-60 polypeptide bands. Fluorography of the gels revealed about 20 labelled plasma membrane glycoproteins. Some strain-specific differences were detected between the samples in all the groups, but no correlation with rheumatoid arthritis could be demonstrated.