Gene profiling of scleroderma skin reveals robust signatures of disease that are imperfectly reflected in the transcript profiles of explanted fibroblasts

Abstract

Objective. To determine whether biopsy specimens obtained from systemic sclerosis (SSc) lesions show a distinctive gene profile, whether that gene profile is maintained in fibroblasts cultured from SSc skin biopsy specimens, and whether results from tissue obtained from multiple clinical centers can be combined to yield useful observations in this rare disease.Methods. Biopsy samples and passaged fibroblasts were stored in RNAlater solution prior to processing for RNA. RNA from SSc and control skin biopsy specimens, as well as SSc and control explanted passage 4 fibroblasts, from 9 patients and 9 controls was hybridized to Affymetrix HG-U133A arrays. Data were analyzed using the BRB ArrayTools system. When appropriate, findings were followed up with immunohistochemical analysis or TaqMan studies.Results. Biopsy samples obtained from patients with SSc had a robust and distinctive gene profile, with ϳ1,800 qualifiers distinguishing normal skin from SSc skin at a significant level. The SSc phenotype was the major driver of sample clusters, independent of origin. Alterations in transforming growth factor ␤ and Wnt pathways, extracellular matrix proteins, and the CCN family were prominent. Explanted fibroblasts from SSc biopsy samples showed a far smaller subset of changes that were relatively variable between samples, suggesting that either nonfibroblast cell types or other aspects of the dermal milieu are required for full expression of the SSc phenotype.Conclusion. SSc has a distinct gene profile that is not confounded by geographic location, indicating that extended multicenter studies may be worthwhile to identify distinct subsets of disease by transcript profiling. Explanted SSc fibroblasts show an incomplete reflection of the SSc phenotype.

Systemic sclerosis: a prototypic multisystem fibrotic disorder

“…This seminal observation focused attention on the pivotal role of the fibroblast in the pathogenesis of fibrosis and spawned extensive research into the underlying mechanisms (105). Persistent fibroblast activation in the absence of the fibrotic tissue milieu, confirmed more recently by DNA microarray studies (52,106,107), indicates autonomous, signal-independent alterations in cell function. The SSc phenotype is characterized by enhanced ECM synthesis, constitutive secretion of cytokines and chemokines, and increased expression of cell surface receptors for fibrogenic signaling mediators (60).…”

Enhanced fibrillin-2 expression is a general feature of wound healing and sclerosis: potential alteration of cell attachment and storage of TGF-β

“…Our data are in line with results obtained with other fibrotic tissue: (i) Gene array analyses of scleroderma and lung fibrosis tissue showed increased fibrillin-2 gene expression levels. 39,40 (ii) In pressure-induced kidney fibrosis, an increase of fibrillin-2 expression was shown by immunohistochemistry and western blotting. 41 (iii) In a wound-healing study, using an antibody against both fibrillin isoforms, fibrillin was identified in the wound tissue.…”

Transforming Growth Factor-β Receptor Type I-dependent Fibrogenic Gene Program Is Mediated via Activation of Smad1 and ERK1/2 Pathways

“…Based on the observation that SSc fibroblasts exhibit an elevated ratio of TGF-␤ type I to type II receptors we have established an experimental model that mimicked this condition in control dermal fibroblasts by carefully titrating the dose of adenoviral vector expressing TGF-␤RI (14). We found considerable overlap between the genes elevated in this experimental model and those previously reported to be overexpressed by lesional SSc fibroblasts and in scleroderma biopsies in vivo (21,22). Among such genes were collagens type I, III, and V, fibronectin, proline 4-hydroxylase, CTGF, SPARC, IGFBP-3, and other matrix protein-related genes.…”