Scleroderma fibroblasts constitutively express the long pentraxin PTX3.

Objective. PTX3 is a secreted molecule which consists of a C-terminal domain similar to classical pentraxins (e.g. Creactive protein) and of an unrelated Nterminal domain. Unlike the classical pentraxins, PTX3 is expressed in re - sponse to IL-1 and TNF- but not to IL-6. The present study was designed to investigate the expression of PTX3 in normal and scleroderma fibroblasts. Methods. Normal and SSc fibroblasts were cultured in the presence and ab - sence of inflammatory cytokines. PTX3 m R N A e x p ression in fibroblasts was evaluated by Northern analysis. PTX3 protein levels in fibroblast culture me - dium were estimated by ELISA. R e s u l t s. Normal fibroblasts were in - duced to express high levels of PTX3 mRNA by IL-1 and TNF- but not by other cytokines or growth factors. Scle - roderma fibroblasts, unlike normal fi - broblasts, constitutively expressed high levels of PTX3 in the absence of delibe - rate stimulation. The constitutive ex - pression of PTX3 in SSc fibroblasts was not modified by anti-TNF- antibodies or IL-1 receptor antagonist. In con - trast, IFN- and TGF- inhibited the constitutive but not the stimulated ex - pression of PTX3 in SSc fibroblasts. Conclusions. PTX3 is a main feature of activated scleroderma fibroblasts.