Fig 2: Different barrier functions and gene expression profiles of permeability barrier components characterize healthy GP, AGR, and SGR skin regions. (a) Transepidermal water loss levels in healthy GP, AGR, and SGR skin areas. Measurements were carried out with Tewameter TM300 (Courage and Khazaka, Cologne, Germany) on the flexural forearm, axilla, and forehead of healthy individuals (n = 30). Gene expression of the components of (b) cornified envelope formation, (c) corneocyte desquamation, (d) intercellular lipid lamellae, (e) desmosome organization, and (f) tight junction formation in healthy GP, AGR, and SGR skin regions were examined by qRT-PCR. The graphs show the mean ± 95% confidence interval of measured mRNA transcript levels (* p < 0.05, ** p < 0.01, *** p < 0.001, determined by one-way ANOVA followed by Sidac post hoc test). Abbreviations: ABCA12, ABC transporter 12B; AGR, apocrine gland-rich; CDH, cadherin; CDSN, corneodesmosin; CLDN, claudin; DSC, desmocollin; DSG, desmoglein; GP, gland-poor; KLK, kallikrein-related peptidase; KRT, keratin; LCE, late cornified envelope; OCLN, occludin; PKP, plakophilin; SGR, sebaceous gland-rich; SPRR, small proline-rich protein; TEWL, transepidermal water loss; TGM, transglutaminase.