Unique skin abnormality in patients with peanut allergy but no atopic dermatitis

Background: The nonlesional skin of children with atopic dermatitis (AD) with peanut allergy (PA) is associated with increased transepidermal water loss; low urocanic acid (UCA) and pyrrolidone carboxylic acid (PCA), both of which are filaggrin breakdown products; anda reduced ratio of esterified co-hydroxy fatty acid sphingosine ceramides (EOS-CERs) to nonhydroxy fatty acid sphingosine ceramides (NS-CERs) in the skin. The skin barrier of subjects with PA without AD (AD(-)PA(+)) has not been studied. Objective: Our aim was to explore whether AD-PA+ is associated with skin barrier abnormalities. Methods: A total of 33 participants were enrolled, including 13 AD-PA(+), 9 AD(+)PA(+), and 11 nonatopic (NA) participants. Results: The PCA content in the stratum corneum of AD(-)PA(+) subjects was significantly reduced versus that in NA subjects (median level, 67 vs 97 mu g/mg protein [P = .028]). The ratio between cisand trans-UCA decreased significantly from being highest in the NA group (1.62) to lowest in AD(+)PA(+) group (0.07 [P <.001 vs in the NA group; P = .006 vs in the AD(-)PA(+) group]), with the AD-PA(+) group having an intermediate cis/trans-UCA ratio (1.17 [P = .024 vs in the NA group]). The TEWL in AD(-)PA(+) subjects did not differ from that in the group with NA skin. Interestingly, AD-PA(+) subjects had an increased EOS/NS-CER ratio versus that in the group of subjects with NA skin (1.9 vs 1.3 [P = .008]), whereas the AD(+)PA(+) group had a decreased proportion of EOS-CERs (0.8 [P = .001] vs in the AD-PA(+) group). Conclusion: Our data demonstrate that irrespective of AD, PA is associated with decreased skin cis-UCA and PCA content. An increase in skin EOS-CER/NS-CER ratio separates the AD-PA(+) group from the AD(+)PA(+) and NA groups.