Linking Power Doppler Ultrasound to the Presence of Th17 Cells in the Rheumatoid Arthritis Joint

Abstract

BackgroundPower Doppler ultrasound (PDUS) is increasingly used to assess synovitis in Rheumatoid Arthritis (RA). Prior studies have shown correlations between PDUS scores and vessel counts, but relationships with T cell immunopathology have not been described.Methodology/Principal FindingsPBMC were isolated from healthy controls (HC) or RA patients and stimulated ex vivo with PMA and ionomycin for 3 hours in the presence of Golgistop. Paired synovial fluid (SF) or synovial tissue (ST) were analysed where available. Intracellular expression of IL-17, IFNγ, and TNFα by CD4+ T cells was determined by flow cytometry. Synovial blood flow was evaluated by PDUS signal at the knees, wrists and metacarpophalangeal joints of RA patients. Serum, SF and fibroblast culture supernatant levels of vascular endothelial growth factor-A (VEGF-A) were measured by ELISA. The frequency of IL17+IFNγ-CD4+ T cells (Th17 cells) was significantly elevated in peripheral blood (PB) from RA patients vs. HC (median (IQR) 0.5 (0.28–1.59)% vs. 0.32 (0.21–0.54)%, p = 0.005). Th17 cells were further enriched (mean 6.6-fold increase) in RA SF relative to RA PB. Patients with active disease had a higher percentage of IL-17+ T cells in ST than patients in remission, suggesting a possible role for Th17 cells in active synovitis in RA. Indeed, the percentage of Th17 cells, but not Th1, in SF positively correlated with CRP (r = 0.51, p = 0.04) and local PDUS-defined synovitis (r = 0.61, p = 0.002). Furthermore, patients with high levels of IL-17+CD4+ T cells in SF had increased levels of the angiogenic factor VEGF-A in SF. Finally, IL-17, but not IFNγ, increased VEGF-A production by RA synovial fibroblasts in vitro.Conclusions/SignificanceOur data demonstrate a link between the presence of pro-inflammatory Th17 cells in SF and local PDUS scores, and offer a novel immunological explanation for the observation that rapid joint damage progression occurs in patients with persistent positive PDUS signal.

Enhanced and persistent levels of interleukin (IL)-17+CD4+ T cells and serum IL-17 in patients with early inflammatory arthritis

“…+ T cells in peripheral blood, we were unable to demonstrate relationships between active disease (joint counts, ESR, global assessments, CRP or DAS28), in agreement with our previous work [14]. This is in contrast with Leipe et al, who reported a positive correlation between Th17 cells in peripheral blood and CRP in patients with early RA and psoriatic arthritis [3], all of whom were also treatment-naive, but had shorter symptom duration than our cohort.…”

“…This study shows that the levels of peripheral IL-17 peripheral blood compared with healthy controls [3,14,[18][19][20][21]. However, conflicting data exist [22,23], including a recent study which showed that patients with early RA within a cohort of EIA had lower levels of Th17 cells [24].…”

“…Indeed, we have previously demonstrated increased levels of IL-17 Additionally, power Doppler ultrasound signal, used increasingly as a marker of active synovitis, was associated with increased levels of T helper type 17 (Th17) cells in RA SF, and IL-17 + T cells were higher in synovial tissue of patients with active disease compared to patients in remission [14].…”

Psoriasis

“…On the other hand, differences in the genetic background of the two conditions do exist and unique genetic determinants have been identified, although not at genome-wide significance (Liu et al 2008). Nevertheless, PsA shares several key cellular and molecular mediators with psoriasis, such as lymphocytes infiltrating the inflamed skin or joint (Pitzalis et al 1996;Shen et al 2006) and critical cytokines such as tumor necrosis factor (TNF), IL-23, and IL-17 (Gullick et al 2010). Genetic association with class I HLA molecules and clinical evidence supports an important role of CD8 T cells in PsA, with the presence of oligoclonally expanded CD8 T cells in the joint fluids of individuals with active PsA (Costello et al 2001).…”

Anti-tumour necrosis factor treatment increases circulating T helper type 17 cells similarly in different types of inflammatory arthritis

“…Increased frequencies of Th17 cells have been observed in the peripheral blood of patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA) compared to healthy controls [2,3] and have been shown to be further enriched in synovial fluid from these patients, as well as in synovial tissue from RA and PsA patients, where their levels correlate with systemic inflammation [4][5][6].…”