Background Rheumatoid arthritis (RA) is an immune-mediated inflammatory disease of unknown aetiology. Recent work has shown that systemic autoimmunity precedes inflammation of the synovium in RA patients. We developed a method to study the cellular composition of lymph nodes in the earliest phases of RA.
Objective Cross-sectional analysis of the phenotype and functional characteristics of T cells from lymph nodes of individuals in different phases of rheumatoid arthritis.
Materials and Methods Seven individuals with arthralgia but without any evidence of arthritis upon physical examination who were/but positive for IgM rheumatoid factor (IgM-RF) and/or anti-citrullinated protein antibodies (ACPA; RA risk group) and 7 DMARD and biological naïve RA patients were included in the study. All study subjects underwent ultrasound-guided inguinal lymph node biopsy. T cell subsets T-helper (Th)1, cytotoxic T cell (Tc)1, Th2, Tc2, Th17, Tc17, regulatory T cells (Treg) and follicular T cells (Tfh) were analysed by multi-colour flow cytometry. Cytokine profiles were determined after stimulation with Phorbol Myristate Acetate (PMA) and Ionomycin in the presence of Brefeldin A and Golgi Stop. We used directly labelled antibodies for CD45, CD3, CD4, CD8, IFN-y (Th1/Tc1), IL-4 (Th2/Tc2), IL-17A (Th17/Tc17) foxp3, and IL-10 (Treg).
Results Different T-helper cell subsets could be distinguished in the RA risk and arthritis group. An increase of CD4+IL-17A T cells (Th17; p = 0.04) and of CD4+IL-10 producing T cells (p = 0.014) could be observed in the early arthritis group compared to the RA risk group. Interestingly, a significant correlation between CD4+IL-10 producing T cells and ACPA titers (r = 0.78; p = 0.0016) and between CD4+IL-17A producing T cells and IgM-RF levels (r = 0.57; p = 0.04) was found when combining both study groups. In addition, within the RA risk group the levels of CD4+ IL-10 producing T cells correlated significantly with the TOTTJC28 (r = 0.8097; p = 0.03). Within the early arthritis group no significant correlations between T cell subsets and disease activity were found.
Conclusions Flow cytometry analysis of cells collected using ultrasound-guided inguinal lymph node biopsy suggests an increase in activated T cells producing IL-17A and IL-10 in patients with early RA. Moreover, the number of these T cells correlates with autoantibody levels suggesting an important role of these T cells in the humoral autoimmune response. These data indicate that inflammatory changes in lymph nodes are present during the earliest phases of RA which may provide new insights in early immuno-logical changes associated with RA pathogenesis.