#Skin barrier damage after exposure to para-phenylenediamine

p-Phenylenediamine (#PPD) is a strong contact allergen used in hair dye known to cause allergic contact dermatitis (ACD). Both private and occupational exposure to PPD is frequent, but the effect of PPD exposure in non-allergic occupational exposed individuals is unknown..

..RNA-sequencing demonstrated down-regulation of tight junction (TJ) and stratum corneum (SC) proteins in skin of severe ACD patients after PPD exposure. Claudin-1 (CLDN1), claudin-8 (CLDN8), claudin-11 (CLDN11), CLMP, occludin, MAGI1, and MAGI2 expression were downregulated in severe ACD patients. CLDN1 and CLMP expression were downregulated in non-responding hairdressers and mild ACD patients. Filaggrin-1(FLG1), filaggrin-2 (FLG2) and loricrin expression were downregulated in ACD individuals. Confocal microscopy images showed down regulation of claudin-1 and filaggrin 1 and 2. In contrast, 3D skin cultures showed up-regulation of filaggrin-1 in response to PPD but down-regulation of filaggrin-2.

Conclusion
PPD-exposed skin is associated with extensive transcriptomic changes including down-regulation of TJ and SC proteins even in the absence of clinical symptoms.

Mechanisms of skin barrier defects in para-phenylenediamine allergic contact dermatitis patients and healthy hairdressers after exposure demonstrate significant downregulation of tight junction and stratum corneum proteins

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