Effects of Extended-Release Polyhexanide on Inflammatory Cytokine Expression and Disease Severity Following Staphylococcus Aureus Exposure in a Murine Dermatitis Model

Background: The skin functions as an active immunologic interface in which microbial exposure triggers epithelial stress responses and downstream inflammatory signaling. Staphylococcus aureus is a potent inducer of cutaneous inflammation and has been shown to stimulate expression of IL-36 cytokines, which function as upstream amplifiers of immune activation. The extent to which modulation of the cutaneous microenvironment influences these signaling pathways remains incompletely understood. Objective: To evaluate the effects of cutaneous microenvironment modulation using extended-release polyhexanide formulation GX-03 on a murine model of Staphylococcus aureus-induced dermatitis. Specifically, we evaluated whether pretreatment with GX-03 was associated with changes in IL-36-mediated epithelial stress signaling, selective downstream cytokine expression, and clinical disease severity following standardized epicutaneous Staphylococcus aureus exposure. Methods: Forty female C57BL/6 mice underwent epicutaneous Staphylococcus aureus challenge following either no pretreatment or four days of topical GX-03 pretreatment. Animals were randomized equally into two treatment groups. Following exclusion of four animals because of premature loss of the occlusive dressing, analyses were performed on 18 animals per group. Disease severity was assessed using a validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD) scoring system. Skin tissue cytokine expression was quantified by Western blot analysis. Results: GX-03 pretreatment significantly reduced disease severity compared with untreated controls (mean vIGA-AD 0.83 vs. 2.44, p < 0.001). Significant reductions were observed in IL-36α (49.9%), IL-36γ (50.9%), IL-31 (67.7%), and IL-4 (16.7%). IL-13 expression was unchanged (p = 0.988). Conclusions: Pretreatment with extended-release polyhexanide (GX-03) reduced disease severity and was associated with decreased expression of IL-36α, IL-36γ, IL-31, and IL-4 following epicutaneous Staphylococcus aureus exposure, while IL-13 expression remained unchanged. These findings suggest that modulation of the cutaneous microenvironment is associated with selective alterations in inflammatory cytokine expression following microbial challenge. Additional studies incorporating microbiologic, histologic, and mechanistic endpoints are needed to further define the biological mechanisms responsible for these observations.