The TGF-β1 Signaling Pathway as an Attractive Target in the Fibrosis Pathogenesis of Sjögren’s Syndrome

Figure 5

TGF-β1 induces transcription of the SMAD complex and EMT-related molecular markers in healthy SGEC. SMAD 2, 3, and 4, SNAIL, E-cadherin, vimentin, and collagen type I gene expression were quantified by semiquantitative RT-PCR (a, b) and real-time PCR (c) in healthy SGEC treated with TGF-β1 for 24 h, untreated control cells, and pSS SGEC. The images show that TGF-β1 treatment determined increased levels of SMAD 2, 3, and 4 and Snail gene expression comparable to those observed in pSS SGEC. The increasing gene expression of mesenchymal marker vimentin and collagen type I and the decreased gene expression of epithelial marker E-cadherin were also revealed. Band intensities were analyzed by densitometric analysis performed by gel image software, normalized against that of GAPDH, and expressed in arbitrary units (b). In the real-time PCR (c), β2-Microglobulin-normalized relative expression levels of SMAD 2, 3, and 4, SNAIL, E-cadherin, vimentin, and collagen type I mRNA are shown. Gene expression changes observed in real-time PCR analysis are in agreement with the results monitored by semiquantitative RT-PCR; SMAD 2, 3, and 4, Snail, vimentin, and collagen type I gene expression was increased upon treatment of healthy SGEC with TGF-β1, while E-cadherin resulted decreased (data represent ; ). Asterisks indicate statistical significance, . M = marker; Vim = vimentin; E-cadh = E-cadherin.

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