TGFβ Isoforms and Decorin Gene Expression are Modified in Fibroblasts Obtained from Non-syndromic Cleft Lip and Palate Subjects

Abstract

Interaction between extracellular matrix (ECM) and cytokines is thought to be crucial for palatal development. The localization of transforming growth factors (TGFa and TGFβ isoforms) in craniofacial tissues suggests that they carry out multiple functions during development. In the present report, we studied TGFa, TGFβ₁, and TGFβ₃ expressions and their effects on ECM macromolecule production of normal and cleft palatal fibroblasts in vitro, to investigate the mechanisms by which the phenotypic modulation of fibroblasts occurs during the cleft palate process. The results indicated that, while TGFa mRNA was not evidenced in CLP or normal fibroblasts, a reduced TGFβ₁ hybridization signal was detected in CLP fibroblasts. In addition, these secreted more active TGFβ₃ than TGFβ ₁, as evaluated in a biological assay. The CLP phenotype, which differed from the normal one because of its higher PG decorin expression and greater production of GAG and collagen, was further modified by the addition of growth factors. In fact, in CLP fibroblasts, TGFa and TGFβ₁ down-regulated PG decorin transcript, TGFβ₁ increased collagen and GAG in both cellular and extracellular compartments, and TGFβ₃ promoted secretory processes of cells. In conclusion, the data represent the first report in a human model in vitro that TGFβ₁ and β ₃ are differently expressed and are correlated to the CLP phenotype. Thus, strength is given to the hypothesis that TGFβ₃ isoforms are the potential inducers of phenotypic expression in palatal fibroblasts during development and that an autocrine growth factor production mechanism may be responsible for the phenotypic modifications.