398 Differential UV-induced cytokine expression in dependence to skin microbiome in Polymorphic Light Eruption

Polymorphic light eruption (PLE) is a chronic intermittent skin disease that develops episodes after sun exposure, most often in spring or early summer. Although the pathogenesis not fully understood, evidence indicates microbiome may play crucial role. Preclinical data have shown can regulate UV-induced cytokine expression and modulate subsequent immune response. We therefore hypothesized of PLE patients might exposure. To test this hypothesis, we conducted randomized, placebo-controlled, double-blind study (6 patients, 15 healthy volunteers, CTRL). analyzed levels blister fluid obtained from UV-exposed unexposed, disinfected non-disinfected skin. found overall production was impaired (in exposed unexposed skin). Of 71 cytokines measured, 8 (MCP4, SIRT2, IL18, TRAIL, IL33, STAMBP, X4EBP1, CSF1) had significantly lower than CTRL, when comparing both once (MED 1.64 - 1.75 mW/cm2). Disinfection rescued particularly evident repeated mild UV exposures, where level 45 including IL18R1, CCL11, CXCL6, among others upregulated (at vs. sites, to 4 times at consecutive days). Multiple inflammatory pathways such as regulation response, T-helper 1 cell production, NKT proliferation showed strong enrichment. Taken together, these results demonstrated disinfection normalized which UV-driven directed by microbiome.