Abstract
Anti-histone and anti-chromatin antibody responses play a central role in the autoimmune response of systemic lupus erythematosus (SLE). Furthermore, anti-histone H1 antibodies are essential for the formation of the lupus erythematosus cell (LEC) phenomenon. In this study, the binding properties of LEC+ and LEC- SLE sera to chromatin-associated nuclear antigens (histones H1, H2A, H2B, H3, H4; complexes of H2A-H2B, [H2A-H2B]-DNA, H1-DNA; total and H1-stripped chromatin; native and denatured DNA) were investigated. In addition, sera from patients with drug-induced lupus (by procainamide, hydralazine, or quinidine), as well as from patients with rheumatoid arthritis and osteoarthritis, were assessed. Enzyme-linked immunosorbent assay was used to detect specific antibody binding. Mirroring the important role of histone H1 in the formation of LE cells, anti-histone H1 reactivity was 8-fold higher in LEC+ sera than in LEC- sera. In addition, reactivities to most of the other antigens tested, i.e., other histones and histone-DNA complexes as well as chromatin and DNA, were significantly higher in LEC+ sera than in LEC- sera. All but 1 serum sample from the patients with drug-induced lupus were negative for LE cell formation as well as for anti-histone H1 reactivity, but displayed high antibody reactivities to histone-DNA complexes, including chromatin. Sera from patients with rheumatoid arthritis and osteoarthritis did not show significant binding to these antigens. When comparing the clinical features of LEC+ and LEC-SLE patients, severe organ involvement, including nephritis and central nervous system involvement, was common in the LEC+ group, but rare in the LEC- group. A positive LE cell phenomenon not only correlated with the presence of high anti-histone H1 antibody levels in SLE, but also indicated serologically and clinically active disease with major organ involvement.
Highlights
The presence of autoantibodies directed to citrullinated antigens in serum is highly specific for rheumatoid arthritis (RA)
We discuss the presence of anti-keratin antibodies (AKA) of the IgG class in patients with defined juvenile idiopathic arthritis (JIA)
Our study revealed that AKA was present overall in 18/29 patients (62%) with severe JIA and in 12/26 patients (46,2 %) with non-severe disease, this did not reach statistical significance (P = 0,18)
Summary
The presence of autoantibodies directed to citrullinated antigens in serum is highly specific for RA. Anti-CCP concentrations (expressed in Units per mg total IgG) were on average 1.34 times higher in SF compared to serum (n = 20, P < 0.05) or 1.37 when only positive samples were included (n = 11, P < 0.05) Conclusion: Citrullinated antigens are present in the synovia of both RA and control patients with similar prevalence. At higher concentrations (>1ng/μl) of RNA-oligonucleotides unspecific hybridization-signals prevailed in tissues of all diseases (even in normal controls) The combination of both methods (in situ-hybridization and immunohistochemistry) identifies the single cells inside the synovial lining layer which contains the highly expressed RAB3 “Kreisler” (maf B) gene. Conclusions: These data demonstrates for the first time that statins (and fluvastatin) are able to inhibit an endothelial proadhesive and pro-inflammatory phenotype induced by different stimuli including anti-β2GPI antibodies or pro-inflammatory cytokines These findings suggest a potential usefulness for statins in the prevention of the APS pro-atherothrombotic state
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