Topical antibiotics limit depigmentation in a mouse model of vitiligo

Oral neomycin administration impacts the gut microbiome and delays vitiligo development in mice, and topical antibiotics may likewise allow the microbiome to preserve skin health and delay depigmentation. Here, we examined the effects of 6‐week topical antibiotic treatment on vitiligo‐prone pmel‐1 mice. Bacitracin, Neosporin, or Vaseline were applied to one denuded flank, while the contralateral flank was treated with Vaseline in all mice. Ventral depigmentation was quantified weekly. We found that topical Neosporin treatment significantly reduced depigmentation and exhibited effects beyond the treated area, while Bacitracin ointment had no effect. Stool samples collected from four representative mice/group during treatment revealed that Neosporin treatment aligned with reduced abundance of the Alistipes genus in the gut, while relevant changes to the skin microbiome at end point were less apparent. Either antibiotic treatment led to reduced expression of MR1, potentially limiting mucosal‐associated invariant T‐cell activation, while Neosporin‐treated skin selectively revealed significantly reduced CD8+ T‐cell abundance. The latter finding aligned with reduced expression of multiple inflammatory markers and markedly increased regulatory T‐cell density. Our studies on favorable skin and oral antibiotic treatment share the neomycin compound, and in either case, microbial changes were most apparent in stool samples. Taken together, neomycin‐containing antibiotic applications can mediate skin Treg infiltration to limit vitiligo development. Our study highlights the therapeutic potential of short‐term antibiotic applications to limit depigmentation vitiligo. Antibiotic ointments were topically applied to vitiligo‐prone, pmel‐1 mice, evaluating the consequences of short‐term antibiotic treatment on the kinetics of depigmentation, microbial composition, infiltrating T‐cell subsets, and inflammatory responses in the skin. Resulting findings can serve to guide the development of standalone or adjunct therapies to limit depigmentation in vitiligo patients.