Comparative analysis of autoantibodies targeting peptidylarginine deiminase type 4, mutated citrullinated vimentin and cyclic citrullinated peptides in rheumatoid arthritis: associations with cytokine profiles, clinical and genetic features.

Antibodies against cyclic citrullinated peptides (anti-CCP) are widely used for diagnosis of rheumatoid arthritis (RA). We performed a comparative analysis of antibodies targeting the citrullinating enzyme peptidylarginine deiminase type 4 (anti-PAD4) and mutated citrullinated vimentin (anti-MCV) with anti-CCP autoantibodies in RA patients and examined their relationships with clinical parameters, cytokine profiles and the PADI4 gene. Autoantibodies were examined by enzyme-linked immunosorbent assay (ELISA) in sera of 170 RA patients and 103 controls. Cytokine profiles were measured using a multiplex system. PADI4 polymorphisms (89 G > A, 90 T > C and 92 G > C) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Anti-PAD4, anti-MCV and anti-CCP autoantibodies were detected in 24, 61 and 74% of RA patients, respectively. Positive correlations were observed between anti-PAD4 and disease duration; anti-CCP and erythrocyte sedimentation rate (ESR); anti-MCV and ESR and C-reactive protein. Anti-MCV antibodies were associated with high disease activity score 28 (DAS-28) in early RA. Concentrations of T helper type 1 (Th1) [tumour necrosis factor (TNF)-α, interleukin (IL)-12, IL-2, IL-1ß], Th2 (IL-4, IL-6, IL-10, IL-13) and Th17 (IL-17) cytokines were higher in RA than in controls. Th2 and, to a lesser extent, Th1-related cytokines, showed positive correlations with anti-MCV and anti-CCP. The GTG haplotype in PADI4 was associated with anti-CCP and anti-MCV, but not anti-PAD4 antibodies. In conclusion, anti-PAD4 antibodies are detected mainly in established RA, which is in contrast to the early detection of antibodies against citrullinated peptide/proteins (ACPAs). Among autoantibodies, anti-MCV appear to perform better as markers of disease activity. Furthermore, anti-CCP and anti-MCV are associated genetically with the citrullinating enzyme PAD4 and are related strongly to Th1 and Th2 cytokines, suggesting a feed-forward loop between cytokines and ACPA production.

Macrophage migration inhibitory factor (MIF): genetic evidence for participation in early onset and early stage rheumatoid arthritis.

Macrophage migration inhibitory factor (MIF) is an upstream pro-inflammatory cytokine that is associated with the pathogenesis of autoimmune inflammatory diseases including rheumatoid arthritis (RA). Two polymorphisms in the upstream region exist in the MIF gene and are associated with RA susceptibility or severity in different populations. In this case-control study, we investigated whether MIF polymorphisms are associated with RA susceptibility or activity in a western Mexican population .The relationship of MIF levels with clinical features of disease also was assessed. Genotyping of the -794 CATT5-8 (rs5844572) and the -173 G>C (rs755622) polymorphisms was performed by PCR and PCR-RFLP respectively on 226 RA patients and 210 healthy subjects. Serum MIF levels were determined by ELISA. We found a significant association between the -794 CATT5-8 6,7 MIF genotype with RA. Moreover, we detected an association between the -794 CATT7 allele with early onset RA. The -794 CATT7 and -173(*)C alleles, which are in linkage disequilibrium, were associated with high disease activity on RA patients. A positive correlation between circulating MIF levels and C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, anti-citrullinated protein/peptides antibodies and TNFα was detected. MIF levels appear to be associated with disease progression rather than disease activity, which is distinct from the established relationship between disease activity and TNFα levels. In conclusion, the MIF gene and protein are associated with RA in a western Mexican population, with a main contribution onto early onset and early stages of disease.

PRL -1149T allele (rs1341239) is associated with decreased risk of rheumatoid arthritis in population from southern Mexico: analysis of mRNA expression and PRL serum levels.

INTRODUCTION: Prolactin (PRL) is a sex hormone with immunomodulatory properties, and it is associated with the clinical activity of rheumatoid arthritis (RA). The -1149G>T polymorphism at the prolactin (PRL) gene has been associated with autoimmune diseases, but its functional effect is unclear. OBJECTIVE: To analyze the association of the PRL -1149G>T polymorphism with disease susceptibility, mRNA, and protein expression of PRL in RA patients from Southern Mexico. METHODS: We included 300 RA patients and 300 control subjects (CS). Genotypes were identified by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique, the PRL mRNA expression was determined by real-time PCR, and PRL serum levels were measured by enzyme-linked immunosorbent assay. RESULTS: Applying genetic models of inheritance (dominant, recessive, and additive), we found an association between the T allele and decreased RA susceptibility (OR = 0.55, 95% CI 0.35-0.87, p = 0.009; OR = 0.09, 95% CI 0.012-0.76, p = 0.011; OR = 0.49, 95% CI 0.32-0.76, p = 0.001, respectively). RA patients had higher mRNA expression and soluble levels of PRL than CS (p < 0.05). The PRL serum levels were similar in RA and CS according to genotypes. However, in CS, carriers of GT and TT genotypes showed lower PRL mRNA expression than GG genotype carriers (7.1-fold and 20-fold respectively, p = 0.006). CONCLUSIONS: This study demonstrated that the PRL -1149T allele is a genetic marker of decrease risk to RA in population from Southern Mexico, and it is associated with low PRL mRNA. KEY POINTS: • PRL -1149T allele is a marker of decreased RA susceptibility in population from southern Mexico. • PRL -1149TT genotype is associated with low PRL mRNA expression. • RA patients have higher mRNA expression and soluble levels of PRL than healthy subjects. • PRL serum levels are higher in those RA patients with < 2 years of disease evolution.