Topical exposure to di(2-ethylhexyl) phthalate aggravates atopic dermatitis: an integrated network toxicology,...

Di(2-ethylhexyl) phthalate (DEHP) is one of the most widely used plasticizers; however, whether cutaneous DEHP exposure affects atopic dermatitis (AD) remains unclear. We combined network toxicology, transcriptomic analysis, machine learning, in vivo and in vitro experimental validation, and molecular docking to investigate whether cutaneous DEHP exposure exacerbates AD. ADMETlab 3.0 profiling of DEHP and its major metabolites predicted skin sensitization as one of the higher-probability toxicity endpoints among the evaluated computational outputs. We subsequently intersected DEHP-related targets with AD-associated genes and identified 62 shared targets. The shared targets were enriched in biological processes related to T-cell proliferation, cell adhesion and leukocyte extravasation, as well as inflammatory pathways including JAK-STAT, MAPK and PI3K-Akt signaling. Using STRING and Cytoscape, we constructed a "DEHP-shared targets-pathways-AD" network and prioritized eight hub genes for further investigation. Bulk transcriptomic analysis, together with feature-prioritization results from five machine-learning models, supported the relevance of most candidate genes, six of which were significantly upregulated in AD lesions. Importantly, in vivo experiments demonstrated that topical DEHP exposure exacerbated MC903-induced AD-like dermatitis in BALB/c mice. This exacerbation was accompanied by increased expression of vascular and immune-related genes, including SELE, SELP, CXCR1, and ITGAL. Immunohistochemical staining further supported this vascular-immune activation pattern, revealing increased SELE and SELP expression in ear skin lesions in the MC903 + DEHP group, compared with the MC903 + vehicle group. In vitro experiments also showed that DEHP stimulation upregulated SELE and SELP expression in endothelial cells. Collectively, these findings implicate endothelial adhesion, leukocyte migration, and immune-cell activation in DEHP-associated exacerbation of AD-like inflammation. Finally, molecular docking suggested potential binding modes between DEHP and these proteins, providing structural hypotheses for their possible involvement in this process. Together, our findings indicate that cutaneous DEHP exposure may exacerbate AD by promoting endothelial adhesion and immune-cell infiltration, thereby intensifying skin inflammation.