Intraarticular glucocorticoid treatment reduces inflammation in synovial cell infiltrations more efficiently than in synovial blood vessels

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Abstract
Objective To investigate whether intraarticular (IA) glucocorticoid (GC) therapy diminishes synovial cell infiltration, vascularity, expression of proinflammatory cytokines, and adhesion molecule levels in patients with chronic arthritides. Methods Thirty‐one patients with chronic arthritides received a single IA injection of triamcinolone hexacetonide to treat active large‐joint inflammation. Synovial biopsy specimens were obtained with arthroscopic guidance before and 9–15 days after injection. The presence of T lymphocytes, macrophages, intercellular adhesion molecule 1 (ICAM‐1), vascular endothelial growth factor (VEGF), the pan‐endothelial marker CD31, and the proinflammatory cytokines interleukin‐1α (IL‐1α), IL‐1β, tumor necrosis factor (TNF), and high mobility group box chromosomal protein 1 (HMGB‐1) was studied by immunohistochemistry and real‐time reverse transcriptase–polymerase chain reaction. Results IA GC treatment resulted in good clinical response in 29 of 31 joints. After therapeutic intervention, the number of synovial T lymphocytes declined, whereas the number of macrophages remained unchanged. Overall synovial protein expression of TNF, IL‐1β, extranuclear HMGB‐1, VEGF, and ICAM‐1 was reduced at followup tissue sampling, while no significant effects were observed regarding vascularity. In contrast, expression of IL‐1α, VEGF, and cytoplasmic HMGB‐1 protein in vascular endothelial cells was not affected. GC therapy down‐regulated levels of messenger RNA encoding IL‐1α and IL‐1β, but not TNF or HMGB‐1. Conclusion Synovial cell infiltration and proinflammatory cytokine expression were affected in a multifaceted manner by IA GC treatment. Marked reduction of synovial T lymphocytes, TNF, IL‐1β, extranuclear HMGB‐1, ICAM‐1, and VEGF occurred in association with beneficial clinical effects. Unexpectedly, macrophage infiltration and proinflammatory endothelial cytokine expression remained unchanged. These findings may reflect mechanisms controlling the transiency of clinical improvement frequently observed after IA GC injection.