Effects of

Background/purpose: Oral submucous fibrosis (OSF), characterized by excessive collagen deposition by myofibroblasts, is often linked to Areca nuts consumption. Probiotics consumption has shown protective effects against fibrotic diseases, and recently, their metabolic byproducts, known as postbiotics, have demonstrated superior advantages over probiotics. However, studies on the therapeutic impact of postbiotics on OSF have been scarce. Therefore, this study aims to examine the effect of PostBio GK4, a postbiotic derived from Materials and methods: The cytotoxicity of GK4 in normal buccal mucosal fibroblasts (BMFs) and fibrotic BMFs (fBMFs) were assessed. Following this, we evaluated the effects of GK4 on collagen contraction, migratory, and wound healing capacities in arecoline-induced fibrotic BMFs. Next, Western blotting and ELISA were employed to assess GK4's impact on fibrosis-related proteins such as COL1A1, and α-SMA, as well as on TGF-β and Smad2/3 signaling pathway. Results: Arecoline was shown to stimulate cell migratory, contractile and wound healing abilities as well as the expression of α-SMA and COL1A1 in BMFs. Treatment with GK4 reduced all arecoline-induced phenomena in BMFs. Moreover, GK4 diminished the increased expression of TGF-β and Smad2/3. Conclusion: Our findings proposed that GK4 may exert a suppressive effect on arecoline-induced myofibroblast activities via the inhibition of TGF-β and Smad2/3 signaling pathway. Therefore, GK4 holds promise as an adjunct therapeutic approach for intervening in OSF. Further in-vivo and clinical studies are warranted to validate these observations.