Protease nexin-1 messenger RNA levels are not affected by serum or interferon beta in cultured systemic sclerosis fibroblasts.

The aim of the present study was to analyze the effect of serum and human recombinant beta interferon (rIFNbeta) treatment on PN-1 mRNA levels in cultured dermal fibroblasts obtained from the skin of healthy donors and from lesional skin of systemic sclerosis (SSc) patients with the limited (CREST syndrome) or the diffuse form of SSc. Total RNA was isolated from fibroblasts derived from the skin of healthy individuals and from lesional skin of patients with CREST syndrome and the diffuse form of SSc cultured under different conditions (1% or 10% serum-supplemented medium) and treated with 500 IU/ml of rIFNbeta. PN-1 gene expression was assessed by Northern blot analysis. We detected variable PN-1 mRNA levels in normal control fibroblasts as well as in SSc fibroblasts under the different culture conditions (1% or 10% serum-supplemented medium). Accumulated PN-1 mRNA levels found in normal cultured fibroblasts were similar to or even higher than in SSc fibroblasts. PN-1 messenger levels were not significantly altered by IFNbeta treatment in normal or SSc cultured fibroblasts despite the presence of an IFN-stimulated responsive element (ISRE) in the promoter of the PN-1 gene. Our findings suggest that PN-1 expression in SSc fibroblasts at the mRNA level requires further investigation in a large number of SSc patients to better characterize the role of this serpin in the pathogenesis of SSc. We conclude that the transcriptional regulation of PN-1 is not associated with IFNbeta, an antifibrotic cytokine naturally produced by fibroblasts.