Characterization of CD30/CD30L(+) Cells in Peripheral Blood and Synovial Fluid of Patients with Rheumatoid Arthritis

Abstract

The CD30/CD30L signalling system has been implicated in the pathogenesis of several autoimmune and inflammatory conditions. In rheumatoid arthritis (RA), soluble CD30 (sCD30) levels reflect the recruitment of CD30(+) T cells into the inflamed joints and correlate with a positive response to immunosuppressive therapy. The aim of our report was to clarify the role of CD30/CD30L signalling system in the pathogenesis of RA. Our analysis of the CD30L(+) T cell subsets in peripheral blood (PB) and synovial fluid (SF) of RA patients and of the related cytokine profiles suggests the involvement of CD30/CD30L signalling in polarization of T cells towards a Th17 phenotype with proinflammatory features. Moreover, in RA SF nearly 50% of Treg cells express CD30, probably as an attempt to downmodulate the ongoing inflammation. We also show here that the engagement of CD30L on neutrophils stimulated with CD30/Fc chimera may play a crucial role in RA inflammation since activated neutrophils release IL-8, thus potentially amplifying the local inflammatory damage. In conclusion, the results obtained suggest that the complex CD30/CD30L signalling pathway is implicated in the pathogenesis and progression of RA synovitis through a concerted action on several immune effector cells.

Figure 1

Surface CD30L expression upon cell activation. Percentage of CD30L⁺ T cells rapidly increases in the first 15 hours reaching the maximum value (52.4%) after 24 hours from activation with CD3/CD28 beads.

Figure 2

Surface CD30 expression upon cell activation. Percentage of CD30⁺ T cells increases until it reaches the maximum value (87.6%) after 48 hours from activation with CD3/CD28 beads.

Figure 3

Modulation of expression of genes encoding for cytokines in activated SFMCs following incubation with CD30/Fc chimera in controls and patients with RA.

Figure 4

Levels of IL-17 released in the medium by activated SFMCs in presence or absence of CD30/Fc chimera in control subjects and in patients with RA. CD30/Fc chimera stimulus induces the production of IL-17 at 48 hours. ^∗ indicates a P value < 0.05.

Figure 5

FACS analysis of IL-17 producing cells among SFMCs from RA patients, stimulated with CD30/Fc chimera. After 3 hours of CD30/Fc chimera stimulation, the percentage of IL-17 producing T cell is 2.749%, while it is 1.115% in the unstimulated cells.

Figure 6

Neutrophils express CD30L. (a) Gel electrophoresis of RT-PCR products obtained from CD30L transcripts in neutrophils (lane 4) and DG75, used as positive control (lane 5) and negative controls (lanes 2 and 3, resp.). (b) CD30L surface expression obtained with FACS analysis.

Figure 7

Levels of IL-8 released in the medium by healthy donor's neutrophils in presence or absence of CD30/Fc chimera and activated or not with LPS. Neutrophils incubated with LPS and with CD30/Fc chimera displayed a statistical significant increase in IL-8 production. ^∗ indicates a P value < 0.05.