Susceptibility epitope on HLA-DR beta chain for rheumatoid arthritis and the effect of the positivity on the clinical features

Association of complement factor B allotypes and serum biomarkers in rheumatoid arthritis patients and their relatives

The aim of the study was to investigate the allotypic variability of complement factor B (BF) in patients and relatives with rheumatoid arthritis (RA) and its association with serological biomarkers and clinical features of the disease. BF allotypes were determined by high-voltage agarose gel electrophoresis in serum samples of 180 patients with RA, 198 relatives and 98 controls from Southern Brazil. Anticyclic citrullinated peptide (anti-CCP), antimutated citrullinated vimentin (anti-MCV) and IgA-rheumatoid factor (RF) were determined by ELISA and IgM-RF by latex agglutination in all samples. No significant differences were found in the allotypic variants of BF between patients with RA, relatives and controls, nor associations with gender and age of RA onset. BF*S07 allotype was significantly associated with extra-articular manifestations (EAMs; Secondary Sjögren Syndrome, pneumonitis, rheumatoid nodules) in patients with RA (P = 0.02; OR = 6.62). Patients with phenotype BF F had lower positivity for anti-MCV biomarker (P = 0.02; OR = 0.22) and those with allotype BF*S had higher prevalence of this autoantibody (P = 0.02; OR = 3.77). An increased frequency of RF-IgA was detected in relatives of patients with RA with BF FS07 phenotype (P = 0.02; OR = 7.78). Complement BF variability did not influence the development of RA in the studied patients, but BF variants may act as markers of disease prognosis, such as development of EAMs, corroborating with the role of the alternative pathway in the pathogenesis of RA.

Genetic studies, clinical heterogeneity, and disease outcome studies in rheumatoid arthritis

HLA haplotypes influence various clinical RA features considered to reflect severity in case-control and cohort studies. Of particular note is the fact that HLA generally influences the development of erosive and sometimes seropositive and nodular disease; in prospective studies, it noticeably affects joint surgical intervention. These are valuable clues indicating that HLA influences RA severity and chronicity. Nevertheless, HLA influences are generally weak enough so as to require large study subject numbers for detection. As a result, HLA genotyping has restricted usefulness for prediction of clinical severity in individual patients.

Amidolytic and peptidolytic activities of immunoglobulin G present in sera from patients with rheumatoid arthritis, Sjogren's syndrome and systemic lupus erythematosus

Polyclonal immunoglobulin G (IgG) from healthy subjects was found to be capable of hydrolyzing carbobenzoxy-Val-Gly-Arg-p-nitroanilide (a synthetic chromogenic substrate for trypsin) and D-Pro-Phe-Arg-p-nitroanilide (a substrate for plasma kallikrein). Statistically significant elevation of activity against the former substrate was found in patients with rheumatoid arthritis (RA), but not in patients with Sjogren's syndrome (SjS) or systemic lupus erythematosus (SLE). On the other hand, IgG samples from the patients with these three autoimmune diseases showed reduced activity against d-Pro-Phe-Arg methylcoumarinamide, although the differences were not statistically significant. Preliminary studies have shown that two out of three IgG samples from RA patients exhibited the activity of cleaving a pentapeptide, Gln-Arg-Arg-Ala-Ala, whereas virtually no cleavage of the same peptide was observed with IgG from healthy controls or from patients with SjS or SLE.

An association between the natural course of shoulder joint destruction in rheumatoid arthritis and HLA-DRB1*0405 in Japanese patients

To assess the association between HLA-DRB1 alleles and shoulder destruction due to rheumatoid arthritis (RA) in Japanese, we typed for HLA-DRB1 alleles in 100 Japanese RA patients who could be classified into 5 groups: non-progressive (N) with normal radiographs; erosive (E) showing marginal erosion but no collapse; collapse (C) showing subchondral cysts followed by collapse; arthrosis-like (A) showing osteoarthrotic features; and the mutilating (M) showing mutilating bone destruction. The HLA-DRB1*0405 antigen frequency in N, E, C, A, and M types was 55%, 61%, 33%, 71%, 100%, respectively. That in the M type (100%) was significantly higher than that in the others (the N, E, C, and A types; 57%). These findings suggest that the most severe shoulder joint destruction pattern in RA, the M type, is associated with HLA-DRB1*0405.

Polymorphism of TAP1 and TAP2 in Japanese patients with rheumatoid arthritis

Contribution of polymorphism of transporter associated with antigen processing 1 and 2 (TAP1 and 2) alleles to pathogenesis of Japanese rheumatoid arthritis (RA) was studied in 92 RA patients by PCR-RFLP. The allele frequency of TAP2A was slightly low (38.0%) and the frequencies of TAP2B and TAP2C were slightly high (39.7% and 17.9%) in RA, but these differences were not significant. These increases and decrease were due to the positive or negative associations with HLA-DRB1*0405. It was very likely that slight differences in TAP2A, TAP2B and TA2C in RA were secondary phenomenon reflecting an increase in HLA-DRB1*0405. The prevalence of TAP2E allele was low (3.3%, P < 0.01, Pc = not significant) and not correlated with HLA-DRB1*0405.