Notch signaling pathway in keloid disease: enhanced fibroblast activity in a Jagged-1 peptide-dependent manner in lesional vs. extralesional fibroblasts.

Keloid disease (KD) is a fibroproliferative disorder of unknown etiopathogenesis with ill-defined treatment. There is increasing evidence to suggest that aberrant Notch signaling may contribute directly to skin pathogenesis and altered expression of Notch receptors identified in KD. Therefore, the aim of this study was to investigate the Notch signaling pathway in KD compared to normal skin (NS). In this study, we employed in vitro primary cell culture models to elucidate the role of Notch signaling in 44 tissue samples from patients with KD split into keloid and extralesional (EL) samples (internal control) from the same patients, and six NS tissue samples (external control). We show the presence of a significant (p < 0.05) up-regulation of Notch receptors and ligand Jagged-1 (JAG-1) in KD compared to EL and NS tissue samples. Cell spreading, attachment, and proliferation were significantly (p < 0.05) reduced in JAG-1 antisense-treated primary dermal fibroblasts isolated from KD and treated with γ-secretase inhibitor (blocks proteolytic cleavage and activation of Notch), evaluated by real-time cell analyzer (RTCA) on a microelectronic sensory array. In contrast, extralesional skin fibroblasts (ELF) treated with recombinant human JAG-1 (rh-JAG-1) peptide showed significant (p < 0.05) enhancement of cell spreading, attachment, and proliferation in RTCA. Activation/inhibition of JAG-1 and Notch signaling significantly (p < 0.05) altered the behavior of primary keloid fibroblasts and ELF, in cell migration (using a scratch wound assay), invasion (using a 3D invasion assay), and angiogenesis (in vitro coculture tube formation assay). In conclusion, this is the first study to demonstrate a potential role for the Notch signaling pathway in KD progression and that targeting this pathway may provide a novel strategy for treatment of KD.