ABSTRACT
OBJECTIVE: To examine whether human endogenous retrovirus K10 is associated with autoimmune rheumatic disease. DESIGN: A novel multiplex reverse transcription polymerase chain reaction (RT-PCR) system was developed to investigate HERV-K10 mRNA expression in patients with rheumatoid arthritis. METHODS: 40 patients with rheumatoid arthritis, 17 with osteoarthritis, and 27 healthy individuals were recruited and total RNA was extracted from peripheral blood mononuclear cells (PBMCs) and analysed using multiplex RT-PCR for the level of HERV-K10 gag mRNA expression. Southern blot and DNA sequencing confirmed the authenticity of the PCR products. RESULTS: Using the histidyl tRNA synthetase (HtRNAS) gene as a housekeeping gene in the optimised multiplex RT-PCR, a significantly higher level of HERV-K10 gag mRNA expression was found in rheumatoid arthritis than in osteoarthritis (p = 0.01) or in the healthy controls (p = 0.02). CONCLUSION: There is enhanced mRNA expression of the HERV-K10 gag region in rheumatoid arthritis compared with osteoarthritis or healthy controls. This could contribute to the pathogenesis of rheumatoid arthritis.
Subject(s)
Arthritis, Rheumatoid/virology , Autoimmune Diseases/virology , Gene Products, gag/biosynthesis , Retroviridae Infections/virology , Adult , Aged , Aged, 80 and over , Blotting, Southern , DNA, Viral/genetics , Endogenous Retroviruses/genetics , Gene Expression , Gene Products, gag/genetics , Humans , Middle Aged , Osteoarthritis/virology , RNA, Messenger/genetics , RNA, Viral/genetics , Reverse Transcriptase Polymerase Chain Reaction/methods , Sequence Analysis, DNA , Viral ProteinsABSTRACT
Polymerase chain reaction using specific primers, failed to detect HTLV-I amplicons in patients with rheumatic diseases previously shown to possess antibodies to retroviral products. However, by employing broad spectrum oligonucleotide primers, 135 bp amplicons were generated from peripheral blood mononuclear cells and synovial fluid cells. Subsequent cloning and DNA sequencing revealed homology to a number of exogenous and human endogenous retroviruses (HERVs). Furthermore, in combining the presence of type B and C related endogenous retroviruses, a significant association (p=0.014) was apparent for chronic autoimmune rheumatic diseases as compared to controls. Reverse transcription polymerase chain reaction of RNA derived from patients, healthy controls and cell lines (U937, BJAB, human endothelial lung fibroblasts) demonstrated ubiquitous expression of HERV-K10 and RTVL-H2. Furthermore messenger RNA expression of HERV-K10 was enhanced in fibroblasts infected with human cytomegalovirus. It is plausible that subsequent production of HERV peptides could explain the presence of anti-retroviral antibodies in cohorts of patients with autoimmune rheumatic diseases.
