Studio dei meccanismi biomoleculari della fibrosi cutanea utilizzando un modello sperimentale in vitro e valutazione dell'efficacia di un ceppo selezionato di probiotico nel contrastare il fenotipo fibrotico.

The protracted inflammatory phase in skin wound healing may lead to dermal fibrosis, and existing therapeutic methods have shown limited efficacy. Exploring alternative approaches, such as those involving specific probiotic strains, could offer potential therapeutic avenues. This study aims to assess the potential of Strephtococuss thermophilus lysate in counteracting the fibrogenic impact of TGF-β1 in normal human dermal fibroblasts (NHDF). NHDF underwent exposure to TGF-β1 to induce a fibrotic phenotype. The assessment included measuring proliferation rates and cell numbers through the IncuCyte® Live Cell Imager system and the trypan blue dye exclusion test. Western blot and immunofluorescence techniques were employed to analyse phenoconversion markers (α-SMA and fibronectin) and collagen I levels. RT-PCR was used to evaluate TGF-β1 mRNA levels. Western blot was also utilized to assess Smad2/3 phosphorylation, β-catenin, and PPARγ expression. Collagen gel retraction and scratch wound healing assays were conducted to study cell contractility function and migration of NHDF. The impact of S. thermophilus lysate, either alone or in combination with TGF-β, was examined across all the aforementioned parameters and markers linked to the TGF-β-induced fibrotic phenotype. The application of S. thermophilus lysate demonstrated a substantial reduction in key mediators and events associated with the abnormal activation of myofibroblasts induced by TGF-β1 in the fibrotic profile. The treatment with S. thermophilus significantly lowered cell proliferation, migration, and myo-differentiation. Furthermore, the probiotic lysate treatment resulted in decreased expression levels of α-SMA, fibronectin, and collagen-I, impacting the collagen contraction ability of activated dermal fibroblasts. Additionally, the probiotic intervention targeted TGF-β1 signaling by reducing Smad2/3 activation, TGF-β1 mRNA levels, and β-catenin expression through the upregulation of PPARγ. This is the first report showing that S. thermophilus lysate had a remarkable anti-fibrotic effect in TGF-β1-activated NHDF by inhibiting Smad signaling. Notably, the probiotic was able to reduce -catenin and increase PPARγ levels. The findings support our point that S. thermophilus may help prevent or treat hypertrophic scarring and keloids.