Table 3.
Effect of synovial microparticles on the release of inflammatory mediators by fibroblast-like synoviocytes from arthritic patients (n = 11)
| Mediator | Control | P* | MP-free synovial fluid | MP (1×) | Nx/Nt | P† | MP (3×) | Nx/Nt | P‡ | |
| Unstimulated | IL-1β | |||||||||
| MCP-1 (pg/ml) | 456 | 4,754 | 0.001 | 469 | 488 | 6/11 | 0.010 | 900 | 4/6 | 0.156 |
| (355–1,292) | (2,492–6,081) | (293–1,241) | (338–1,481) | higher | (346–2,326) | higher | ||||
| sICAM-1 (ng/ml) | 0.09 | 0.40 | 0.007 | 1.04 | 2.00 | 8/11 | 0.010 | 6.07 | 6/6 | 0.031 |
| (0–0.3) | (0–0.76) | (0.34–1.84) | (0.35–4.07) | higher | (0.91–11.75) | higher | ||||
| IL-8 (pg/ml) | 0 | 8,642 | 0.001 | 26 | 301 | 5/11 | 0.008 | 790 | 6/6 | 0.031 |
| (0–564) | (2,954–18,330) | (0–528) | (0–707) | higher | (0–2,100) | higher | ||||
| IL-6 (pg/ml) | 74 | 4949 | 0.001 | 110 | 136 | 7/11 | 0.042 | 436 | 6/6 | 0.031 |
| (24–1,710) | (1,870–22,797) | (30–1,176) | (34–1,937) | higher | (44–3,766) | higher | ||||
| VEGF (pg/ml) | 48 | 79 | 0.014 | 34 | 74 | 10/11 | 0.001 | 111 | 6/6 | 0.078 |
| (11–102) | (7–141) | (1–97) | (28–138) | higher | (27–161) | higher | ||||
| GM-CSF (pg/ml) | 32 | 53 | 0.004 | 31 | 22 | 10/11 | 0.002 | 18 | 6/6 | 0.016 |
| (28–40) | (40–72) | (26–70) | (14–43) | lower | (14–25) | lower | ||||
| RANTES (pg/ml) | 0 | 138 | 0.001 | 0 | 0.2 | 4/11 | 0.031 | 4.2 | 5/6 | 0.062 |
| (0–74) | (46–277) | (0–58) | (0–86) | higher | (0–32) | higher | ||||
Results are medians, with ranges in parentheses. Concentrations of mediators were determined in the culture supernatant of the fibroblast-like synoviocytes (FLS) by ELISA as described in the Materials and methods section. FLS were incubated for 24 hours with 1 ml of culture medium containing 1% FCS (negative control), 975 μl of culture medium supplemented with either (1) 25 μl of interleukin (IL)-1β (final concentration 125 pg/ml; positive control), (2) 25 μl (onefold (1×) or threefold (3×) concentrated) microparticles (MP), or (3) MP-free synovial fluid. P*, positive versus negative control; P†, MP (1×) versus MP-free synovial fluid; P‡, MP (3×) versus MP (1×). Nx/Nt, number of individual culture supernatants that contained elevated or decreased concentrations of mediators after incubation for 24 hours with isolated MP compared with MP-free synovial fluid, divided by the number of patients studied. GM-CSF, granulocyte/macrophage colony-stimulating factor; sICAM-1, soluble intracellular adhesion molecule-1; MCP-1, monocyte chemoattractant protein-1; VEGF, vascular endothelial growth factor.