In this issue of Science Translational Medicine, a report by Loeys et al. on mutations in the fibrillin-1 gene in patients with skin fibrosis (stiff skin) adds a new piece of information on a connective tissue disorder that resembles systemic sclerosis, an autoimmune disease characterized by skin fibrosis and visceral organ involvement.
In contrast with data from Choctaw and Japanese patients, no association was detected between the polymorphic markers of FBN1 and SSc in 2 European Caucasian populations.
To better understand the molecular basis of dermal fibrosis in SSc, we analyzed microarray gene expression in skin of the Tight-skin (Tsk) mouse, an animal model where skin fibrosis is caused by an in-frame duplication in fibrillin-1 (Fbn-1).
These data indicate that anti-fibrillin-1 autoantibodies can induce the activation of normal dermal fibroblasts into a profibrotic phenotype resembling that of SSc by potentially causing the release of sequestered TGF-beta1 from fibrillin-1-containing microfibrils in the ECM.
Subsequently, studies of FBN1 single nucleotide polymorphisms (SNPs) demonstrated that certain FBN1 haplotypes were associated with SSc in both Native American and Japanese patients with limited scleroderma.
The majority of Choctaw American Indians, Japanese, and African Americans with SSc produced IgM and/or IgG autoantibodies to one or more recombinant fibrillin 1 proteins, while <50% of Caucasians with SSc showed seroreactivity.
Increased alpha 1(I) procollagen gene expression in tight skin (TSK) mice myocardial fibroblasts is due to a reduced interaction of a negative regulatory sequence with AP-1 transcription factor.