Bacillus subtilis-derived-exopolysaccharide halts depigmentation and autoimmunity in vitiligo

Vitiligo has a complex multifactorial etiology involving a T-cell mediated autoimmune response to cutaneous melanocytes. Microbial dysbiosis has been assigned a contributing role in vitiligo etiology. Treating vitiligo can be a challenging task and finding novel treatment approaches is crucial. Here, we tested exopolysaccharides (EPS) isolated from B.subtilis as a microbiome-based therapy. Vitiligo-prone h3TA2 mice were treated by weekly intraperitoneal EPS injection for 18 weeks. Depigmentation was measured over time, measuring immune responses at end point. EPS treatment significantly limited the rate of depigmentation. The abundance of cutaneous T cells, specifically CD8+ cytotoxic T cells was reduced while regulatory T cells were more abundant in the skin of treated mice compared to untreated mice. Moreover, EPS treatment was associated with increased numbers of splenic M2 macrophages, elevated splenic IDO expression and a systemic cytokine shift towards a type 2 pattern of cytokines. Importantly, splenocytes retrieved from EPS-treated mice were less responsive to cognate tyrosinase peptide as demonstrated by limited release of IFN- g and other inflammatory cytokines. In summary, EPS isolated from B. subtilis interfered with T-cell mediated depigmentation in the h3TA2 mouse model of vitiligo suggesting that B. subtilis EPS could serve as a novel treatment entity for vitiligo.