Dexamethasone normalizes aberrant elastic fiber production and collagen 1 secretion by Loeys–Dietz syndrome fibroblasts: a possible treatment?

Abstract

Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder characterized by facial dysmorphism, cleft palate, dilation of the aortic arch, blood vessel tortuosity and a high risk of aortic dissection. It is caused by mutations in the transforming growth factor b-receptor 1 and 2 (TGFb-R1 and TGFb-R2) genes. Fibroblasts derived from 12 Loeys-Dietz syndrome patients, six with TGFB-R1 mutations and six with TGFB-R2 mutations, were analyzed using RT-PCR, biochemical assays, immunohistochemistry and electron microscopy for production of elastin, fibrillin 1, fibulin 1 and fibulin 4 and deposition of collagen type I. All LDS fibroblasts with TGFb-R1 mutations demonstrated decreased expression of elastin and fibulin 1 genes and impaired deposition of elastic fibers. In contrast, fibroblasts with TGFb-R2 mutations consistently demonstrated intracellular accumulation of collagen type I in the presence of otherwise normal elastic fiber production. Treatment of the cell cultures with dexamethasone induced remarkable upregulation in the expression of tropoelastin, fibulin 1-and fibulin 4-encoding mRNAs, leading to normalization of elastic fiber production in fibroblasts with TGFb-R1 mutations. Treatment with dexamethasone also corrected the abnormal secretion of collagen type I from fibroblasts with TGFb-R2 gene mutations. As the organogenesis-relevant elastic fiber production occurs exclusively in late fetal and early neonatal life, these findings may have implications for treatment in early life. Further studies are required to determine if dexamethasone treatment of fetuses prenatally diagnosed with LDS would prevent or alleviate the connective tissue and vascular defects seen in this syndrome.

Effects of postnatal dexamethasone treatment on mRNA expression profiles of genes related to alveolar development in an emphysema model in mice

“…5). These results were different from the results of in vivo studies demonstrating the induction by Dex of Tropo in fibroblasts of rat lung and Fbn1 in human skin fibroblasts (Nakamura et al, 2000;Barnett et al, 2011). Considering these facts, expression of Tropo, Fbn1 and Fbln5 was thought to be regulated by com- plicated mechanisms in vivo.…”

Retinoblastoma Protein Modulates the Inverse Relationship between Cellular Proliferation and Elastogenesis

“…One-step RT-PCR Analysis-Human dermal fibroblasts were cultured in 60-mm dishes in 10% FBS DMEM and treated as indicated in the figure legend for 18 h. Total RNA was extracted using the RNeasy Mini kit according to the manufacturer's instructions, 0.5 g of total RNA was added to each one-step RT-PCR (Qiagen One-Step RT-PCR kit), and reactions were set up according to the manufacturer's instructions in a total volume of 25 l. The reverse transcription step, the elastin, and GAPDH PCR reactions were performed as previously described (55). Samples of the elastin and GAPDH PCR products from each reaction were run on agarose gels stained with ethidium bromide.…”

Aortic Aneurysm in Children and Adolescents

“…Treatment of the cell cultures with dexamethasone induced remarkable up-regulation in the expression of tropoelastin, fibulin 1 and fibulin 4 encoding mRNAs, leading to normalization of elastic fiber production in fibroblasts with TGFβ-R1 mutations [78].…”

“…With the increasing availability of whole body imaging, the role of magnetic resonance imaging and multidetector computed tomography are increasing diagnostic modalities in patients with aortic aneurysm/dissection [75,76,77,78]. …”