Scleroderma -- news to tell

Attenuation of expression of extracellular matrix genes with siRNAs to Sparc and Ctgf in skin fibroblasts of CTGF transgenic mice

Transgenic mice that over-express connective tissue growth factor (CTGF) in fibroblasts under the control of an enhancer/promoter element of the Col1a2 gene (Col1a2-CTGF) recapitulate multiorgan fibrosis similar to fibrosis observed in Scleroderma (SSc). In this study we investigate the regulation of secreted protein acidic and rich in cysteine (Sparc) and Ctgf siRNAs on the expression of several extracellular matrix components in the fibroblasts derived from Col1a2-CTGF transgenic mice. Three fibroblast lines were obtained from each of wide type C57BL/6 and CTGF transgenic C57BL/6, and were transfected with Sparc siRNA or Ctgf siRNA. Real-time quantitative RT-PCR and Western blotting were used to examine the transcription and protein levels of type I collagen, CTGF and SPARC. Student's t-tests were used to determine the significance of the results. Our results showed that Col1a2 and Ctgf increased expression at both transcriptional and translational levels in the fibroblasts from the Col1a2-CTGF transgenic mice compared with those in the fibroblasts from their normal wild-type littermate. The treatment with Sparc siRNA or Ctgf siRNA attenuated the mRNA and/or protein expression of the Col1a2, Ctgf and Sparc in these fibroblasts. Sparc and Ctgf siRNAs also showed a reciprocal inhibition at transcript levels. Therefore, our results indicated that both SPARC and CTGF appeared to be involved in the same biological pathway, and they have the potential to serve as a therapeutic target for fibrotic diseases such as SSc.

The pathogenesis of systemic sclerosis

Systemic sclerosis (SSc), also known as scleroderma, is a rare connective tissue disease characterized by vascular and immune dysfunction, leading to fibrosis that can damage multiple organs. Its pathogenesis is complex and poorly understood. Two major clinical subtypes are the limited and diffuse forms. Research into SSc has been hampered by its rarity, its clinical heterogeneity, and the lack of mouse models that accurately recapitulate the disease. Clinical and basic studies have yielded some mechanistic clues regarding pathogenesis. Recent insights gained through the use of microarrays have revealed distinctive subsets of SSc within and beyond the limited and diffuse subsets. In this review, we discuss potential mechanisms underlying the vascular, autoimmune, and fibrotic points of dysregulation. Proper categorization of SSc patients for research studies by use of microarrays or other biomarkers is critical, as disease heterogeneity may explain some of the inconsistencies of prior studies.

[The situation of rare skin diseases in Germany]

In Germany a disease is considered to be "rare" when its prevalence is less than 5:10,000. However, as far as genetic skin diseases are concerned, they are often much more uncommon with a prevalence in the range of 1:100,000. Currently considerable deficits prevail in both diagnosis and treatment of rare skin diseases. Driven by scientific research on rare skin diseases and benefiting from start-up grants of the Federal Ministry for Education and Research (BMBF), the following networks for rare skin diseases were formed: a) epidermolysis bullosa, b) ichthyosis and related keratinisation disorders, c) systemic scleroderma. From a scientific point of view these networks are very successful, they publish in high impact journals and at the same time developed into national centres of reference for the respective disease groups, although formally this status does not exist in Germany. Thus, the 5 year start-up grants considerably improved the clinical care for these three skin disease groups. However, now we are confronted with the threat that the newly formed structures will be difficult to maintain, due to lack of adequate financing. In contrast to France, Germany does not have a "national plan for rare diseases"--probably because the federal structure in Germany is difficult to reconcile with "national plans". In France the situation of clinical care for rare diseases is permanently restructured by the establishment of official national reference centres and by allocation of additional financial means to fulfill these national tasks. In our view, a similar approach is also necessary in Germany.

[Pathogenesis of systemic sclerosis]

Systemic sclerosis is a complex multi-systemic disease with a mostly unresolved pathogenesis. Following an inflammatory reaction, overproduction of collagen and other extra-cellular matrix components leads to a characteristic fibrosis. It remains unclear why this overproduction by fibroblasts and myofibroblasts occurs. Micro-vascular disturbances and endothelial cells, as well as immunomodulation and inflammation are central factors. Besides intrinsic influences, such as genetic polymorphisms, multiple mediators with fibrotic effects such as Platelet Derived Growth Factor, Transforming Growth Factor-beta and Connective Tissue Growth Factor have been characterized. These have become targets for innovative therapeutic strategies that might lead to specific treatments for systemic sclerosis.