P-21 THE ROLE SP-INDUCED MAST CELL ACTIVATION IN LIVER FIBROSIS

No A high density of liver mast cell is associated to liver damage progression in chronic liver diseases. Emerging evidence have suggested that MC degranulation play a crucial role in liver fibrosis induced by hepatic stellate cells (HSCs) activation. However, the contribution of neuroimmune activation of MC by stress related neuropeptide Substance P(SP)remains unexplored. Objective: To evaluate the impact of SP-dependent MC activation in HSCs transdifferentiation. In vitro studies were performed by using Human mast cell line (HMC-1), stimulated with SP (30min), and HSCs cell line (LX-2), subsequently stimulated by 24h with supernatants of SP-MC activated. Supernatants of unstimulated (ns) MC and MC stimulated with 48/80 compound, as well as a direct LX-2 SP (dSP) stimulation were considered as experimental control. Western blotting was performed to measure alfa-smooth muscle actine (α-SMA) expression level, a HSCs transdifferentiation marker, and GADPH, as loading control. A direct stimulation of HSCs by tryptase for 24h and subsequent α-SMA immunostaining by indirect immunofluorescent was performed for qualitative assessment of HSC morphology. Statistical analyses: ANOVA test in experimental replicates (N=3), by using GraphPad Prisma. Significance was set at p<0.05. Despite not statistically differences were observed infold change α-SMA/GADPH level expression among SP stimulated MC and other experimental groups (ns MC, 0.394 ± 0.08; 48/80 MC, 0.256 ± 0.130; SP MC, 0. 274 ± 0.120; dSP, 0.621 ± 0.524) p=0.544, morphological changes of HSCs associated to cell transdifferentiation were observed after 24h of tryptase stimulation. Our results shown that MC tryptase can induce HSCs transdifferentiaton. Short-term effect of SP-MC activation fail to achieve in HSCs activation, suggesting long term MC stimulation need to be explored to evaluate SP-MC impact in HSCs transdifferentiaton. Funding OAIC n°13022.