Supplement Article |
PP19. NO MODIFICATION OF SIL-6R AND GP130 SERUM LEVELS IN ACTIVE AND TREATED PMR PATIENTS
Modulo di Reumatologia Istituti Ortopedici Rizzoli, Bologna, Italy
Background: PMR patients have high systemic levels of IL-6 which correlate with prognosis. IL-6 mediates its activity through two membrane proteins: IL-6R and gp 130 (signal transducing element). Soluble complexes of IL-6R and IL-6, are able to associate to membrane-bound gp130 and thus they mediate intracellular signalling in IL-6R negative cells. Biological activity of sIL-6R/IL-6 complexes can be blocked by soluble gp130. We investigated the modulation of systemic levels of sIL-6R and gp130 in patients both in active disease and during corticosteroid treatment and the ability of peripheral blood mononuclear cells (PBMC) to contribute to circulating levels of these molecules.
Methods: We analyzed sIL-6R and gp 130 serum levels in 44 PMR patients at disease onset and after 1, 3, 6, 12, 24 months of follow-up and in 46 age-matched normal controls (NC). Furthermore we analyzed the ability of PBMC isolated from 13 untreated PMR patients and 13 healthy subjects to release sIL-6R and gp130 in basal condition and upon stimulation with lipopolysaccharide (LPS) and anti-CD3. Serum and supernatant levels were determined by ELISA.
Results: No difference in sIL-6R and gp 130 serum levels were noted between PMR and NC cases, either at disease onset or during follow-up. On the contrary, sIL-6R and gp130 production by PBMC obtained from untreated PMR patients was significantly higher compared to NC either in basal condition or after stimulation with LPS and anti-CD3.
Conclusions: At variance with other inflammatory diseases, we showed neither increase of sIL-6R serum levels nor decrease gp130 levels. Increased production by PMR PBMC does not modify normal serum levels.