Influence of promoter polymorphisms of the TNF-α (-308G/A) and IL-6 (-174G/C) genes on therapeutic response to etanercept in rheumatoid arthritis

Uvod: Genetički faktori su značajni za predviđanje ishoda lečenja bolesnika sa reumatoidnim artritisom (RA). Cilj studije bio je da se ispita uticaj-308G/A TNF-α (rs 1800629) i -174G/C IL-6 (rs1800795) promotorskih polimorfizama na terapijski odgovor na etanercept. Metode: U studiju su bila uključena 73 pacijenta sa aktivnim RA. Terapijski odgovor je procenjivan posle 6 i 12 meseci terapije po kriterijumima Evropske lige protiv reumatizma. Genotipizacija pacijenata za polimorfizme -308G/A TNF-α i -174G/C IL-6 urađena je PCR-RFLP metodom i procenjivan je uticaj genotipova na odgovor na etanercept. Rezultati: Nije bilo razlike u procentu respondera (pacijenti kod kojih se DAS28 popravio gt 1,2) između pacijenata sa TNF-α -308GG, GA i AA genotipom ni posle 6 ni posle 12 meseci tretmana. Posle 12 meseci lečenja procenat respondera je bio značajno veći kod pacijenata sa IL-6 -174GG u odnosu na pacijente sa GC ili CC genotipom (p= 0,006, x2 test). Poređenje pacijenata prema kombinovanim IL-6/TNF-α genotipovima pokazalo je da je IL-6 -174GG / TNF-α -308GG genotip učestaliji kod respondera u odnosu na druge kombinovane genotipove (p= 0.022, x2 test). Tačnije, svi pacijenti sa kombinovanim IL-6 -174GG / TNF-α -308GG genotipom bili su responderi posle 12 meseci terapije etanerceptom. Zaključak: Studija pokazuje da bolesnici sa genotipovima koji se povezuju sa manjom produkcijom TNF-α i IL-6 najbolje odgovaraju na terapiju etanerceptom.Background: The study was undertaken to assess the influence of functional -308G /A TNF-α (rs 1800629) and -174G/C IL-6 (rs1800795) promoter polymorphisms on the therapeutic response to etanercept, a TNF-α blocker, in patients with rheumatoid arthritis (RA). Methods: Seventy-three patients suffering from active RA were studied, at baseline and 6 and 12 months after therapy. The therapeutic response was estimated according to the European League Against Rheumatism response criteria. Patients were genotyped for -308G /A TNF-α and -174G/C IL-6 polymorphisms by the PCR-RFLP method, and the influence of genotype on etanercept response was assessed. Results: No difference in the percentage of responders (patients who had DAS28 improvement gt 1.2) between patients with the TNF-α -308GG and GA and AA genotype was detected after 6 and 12 months of treatment. After 12 months of treatment the percentage of responders was significantly increased in patients with the IL-6 -174GG genotype compared with those with the GC or CC genotype (p=0.006 by Chi-square test). Evaluation of the patients according to their combined IL-6/TNF-α genotypes showed that patients with the IL-6 -174GG / TNF-α -308GG genotype were more frequent among the responders compared to those with other combined genotypes (p=0.022 by Chisquare test). More precisely, all patients with the combined IL-6 -174GG / TNF-α -308GG genotype were responders after 12 months of etanercept treatment. Conclusions: The study suggests that patients who are genetically low TNF-α and IL-6 producers are the best responders to etanercept therapy

Exploring the Link between Hydrodynamic Size and Immunoglobulins of Circulating Immune Complexes in Rheumatoid Arthritis Patients

The function of immune complexes in rheumatoid arthritis (RA) is related to their composition and size. Using dynamic light scattering (DLS), we investigated the link between the RA circulating immune complex (CIC) particles’ size and the CIC immunoglobulin level. In this study, 30 RA patients and 30 healthy individuals were included. IgA, IgG, and IgM were found in all analyzed CICs, but more IgA and IgG were found in RA than in control CICs. In both control and RA CICs, DLS detected 50 particles that differed in size and clustered around two size groups: with a 7.5–164 nm radius and with a 342–1718 nm radius. An increased level of IgA in RA CICs, compared to control ones, was associated with more than 50% of CIC particles. In RA, compared to the control, a higher number of CICs with 28.2 nm, 531 nm, 712 nm, and 1718 nm particles and a lower number of CICs with 78.8 nm particles were detected. This particle distribution pattern did not reflect the changes in the CIC immunoglobulin level. Thus, RA elevated CIC IgA was linked with all these particles (except the 1718 nm particle), the IgM increase was linked with 43.8 nm and 712 nm particles, and the IgG increase was linked with the 712 nm particle only. This study provides the very first data on the association between CIC particles’ size, CIC immunoglobulin level, and RA. It opens the possibility that the size of CICs determined by DLS can be used as a criterion in RA diagnosis or monitoring after a large-scale study confirmation

Dynamic light scattering analysis of immune complexes in sera of rheumatoid arthritis patients

The size of circulating immune complexes (CICs) in rheumatoid arthritis (RA) could be an emerging criterion in disease diagnosis. This study analyzed size and electrokinetic potential of CICs from RA patients, healthy young adults, and RA patients age-matched controls aiming to establish their unique CIC features. Pooled CIC of 30 RA patients, 30 young adults, and 30 RA group's age-matched controls (middle-aged and oldеr healthy adults), and in vitro IgG aggregates from pooled sera of 300 healthy volunteers were tested using dynamic light scattering (DLS). Size distribution of CIC in healthy young adults exhibited high polydispersity. RA CIC patients and their age-matched control showed distinctly narrower size distributions compared with young adults. In these groups, particles clustered around two well-defined peaks. Particles of peak 1 were 36.1 ± 6.8 nm in RA age-matched control, and 30.8 ± 4.2 nm in RA patients. Particles of peak 2 of the RA age-matched control's CIC was 251.7 ± 41.2 nm, while RA CIC contained larger particles (359.9 ± 50.5 nm). The lower zeta potential of RA CIC, compared to control, indicated a disease-related decrease in colloidal stability. DLS identified RA-specific, but also age-specific distribution of CIC size and opened possibility of becoming a method for CIC size analysis in IC-mediated diseases