Arthritis in systemic lupus erythematosus is characterized by local
IL-17A and IL-6 expression
Abstract
Arthritis is a common clinical feature of systemic lupus erythematosus
(SLE) and is usually non-erosive as opposed to rheumatoid arthritis
(RA). While RA synovial pathology has been extensively studied, little
is known about the pathophysiology of lupus arthritis. Here, we aimed to
explore the cytokine and cellular compartments in synovial fluids of SLE
patients with arthritic manifestations. Acellular synovial fluid and
paired serum samples from SLE patients (n=17) were analyzed with
cytokine bead array for T helper associated cytokines. From two SLE
patients, synovial fluid mononuclear cells (SFMC) were analyzed by
multiparameter flow cytometry to dissect T cell, B cell, monocyte and
dendritic cell phenotypes. SLE-derived SFMC were further stimulated in
vitro to measure their capacity for producing IFN and IL-17A. All
patients fulfilled the ACR 1982 classification criteria for SLE.
Clinical records were reviewed to exclude the presence of comorbidities
such as osteoarthritis or overlap with RA. IL-17A and IL-6 levels were
high in SLE synovial fluid. A clear subset of the synovial CD4+ T cells
expressed CCR6+, a marker associated with Th17 cells. IL-17-production
was validated amongst CD4+CCR6+ T cells following in vitro stimulation.
Furthermore, a strong IFN production was observed in both CD4+ and CD8+
cells. Our study shows high IL-17A and IL-6 levels in synovial fluids of
patients with lupus arthritis. The Th17 pathway have been implicated in
several aspects of SLE disease pathogenesis and our data points to Th17
involvement also for lupus arthritis.