Correlation between increased hyaluronan localized in arthritic synovium and the presence of proliferating cells. A role for macrophage-derived factors

Abstract

Objective: To determine whether the increased levels of circulating hyaluronan seen in patients with arthritis also occur locally.

Methods: Biopsy specimens of normal synovium and synovium from patients with various arthropathies were studied using histochemical and immunohistochemical staining procedures, to determine the tissue distribution of hyaluronan and infiltrating cells.

Results: Hyaluronan was found in increased concentrations in inflamed tissues, and was co-localized in sites containing Ki-67+ cells. In vitro analyses showed that macrophage-released factors increased hyaluronan production by fibroblasts. Hydrocortisone inhibited this in vitro production of hyaluronan.

Conclusion: Edema and swelling seen in inflamed joints may be due to the presence of large amounts of hyaluronan. One possible mechanism of action of corticosteroids in the alleviation of acute joint inflammation may occur via the inhibition of hyaluronan production.