Endothelial cells are the major source of sICAM-1 in rheumatoid synovial tissue

Abstract

The objective of this research was to investigate the cellular source of soluble ICAM-1 (siCAM-1) from rheumatoid synovial tissue (RS) and its relation to sICAM-1 in synovial fluid (SF) and serum, and to study the expression of ICAM-1 in isolated cells of RS. sICAM-1 was determined by using the enzyme-linked immunosorbent assay (ELISA) and Western blot analysis in supernatants from RS cultured for short periods (n = 19), in SF (n = 7) and in serum (n = 19). ICAM-1 expression, vascularization and inflammatory infiltration (CD3, CD68, CD22) were characterized immunohistochemically in cytospin preparations (n = 18), cryosections (n = 18) and in conventionally stained paraffin sections (n = 19) of RS. The degree of RS vascularization was analysed morphometrically in immunohistochemically stained cryosections (factor VIII related antigen). We found 90-kD sICAM-1 in supernatants of cultured cells, in SF and in sera. sICAM-1 in cellular supernatant correlated significantly (P < 0.01) with SF sICAM-1. The amount of sICAM in cellular supernatants showed no correlation to the score of inflammatory infiltration, but correlated significantly (P < 0.001) with the vascularization index of RS. The percentage of ICAM-1-expressing cells correlated significantly (P < 0.001) with the percentage of CD68-positive macrophages, but not with CD3- and CD22-positive lymphocytes. Macrophages, multinucleated giant cells and endothelial cells exhibited a higher expression of ICAM-1 as compared to lymphocytes and fibroblasts. The differential expression of ICAM-1 on infiltrating leucocytes and resident cells of RS indicates a functional role of ICAM-1 in the local inflammatory process. SF sICAM-1 originated in RS, but serum sICAM-1 did not. Shedding of sICAM-1 by RS was independent of inflammatory infiltration, but depended on the degree of vascularization, indicating that endothelial cells are the major source of sICAM-1 in RS.

Secretion of immunoregulatory cytokines by mesenchymal stem cells

“…Elevated amounts of a biologically active form of sI-CAM is detected in serum, cerebrospinal fluid, synovial fluid, urine and sputum in pathologies with an underlying inflammatory status, like autoimmune and degenerative diseases [213][214][215] and tumor pathogenesis [216,217] . Different reports point to various cell sources of sICAM in health and pathologies, including endothelial cells [218] , peripheral blood mononuclear cells, keratinocytes, epidermoid carcinoma cell lines, melanoma cells [219] and tumors [216,217,220] . sICAM can be secreted spontaneously or after specific inductions [220] .…”

Mig, GROα and RANTES messenger RNA expression in lining layer, infiltrates and different leucocyte populations of synovial tissue from patients with rheumatoid arthritis, psoriatic arthritis and osteoarthritis

“…In cytocentrifuge preparations five classes of cells were distinguished morphologically, as described previously [19]: multinucleated giant cells, monocytic cells with a large round to oval cytoplasm and a marginally located oval nucleus, lymphocytic cells with a small round cytoplasm and a large round nucleus, fibroblast-like cells with a dendritic or spindle shape and tube-like fragments of blood vessels. Cytological analysis was carried out by one observer, who was unaware of the clinical diagnosis (V.K.).…”

“…The paraffin-embedded slides (Giemsa and haematoxylin/eosin staining) of tissue from all patients were used for standard histopathological evaluation and for scoring of the inflammatory infiltration on a semiquantitative scale of 1-5 [19]. As criteria the degree of enlargement of the synovial lining layer, the density and pattern of mononuclear infiltration and the extent of subsynovial fibrosis were used.…”

Inflammatory infiltrate and interleukin-8 expression in the synovium of psoriatic arthritis - an immunohistochemical and mRNA analysis

“…The paraffin-embedded slides (Giemsa and haematoxylin/eosin staining) of all patients were used for standard histopathological evaluation and for scoring of the inflammatory infiltration on a semiquantitative scale of 1 -5 [19], using the degree of enlargement of the synovial intima, the degree and pattern of lymphocytic infiltration and the extent of subsynovial fibrosis as criteria.…”

“…Tissue for cytospin preparation was prepared, with small modifications, as described previously [19]. Immediately after synovectomy the tissue was minced and dissociated by treatment with 0.5 mg/ml of collagenase type 2 (Sigma, St. Louis, Mo., USA) in RPMI 1640 culture medium for 90 -240 min at 37.5°C, followed by three filtrations through metal mesh (pore size 400 µm).…”