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; and a reduced ratio of esterified ω-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 (ADPA) has not been studied.

Objective: Our aim was to explore whether ADPA is associated with skin barrier abnormalities.

Methods: A total of 33 participants were enrolled, including 13 ADPA, 9 ADPA, and 11 nonatopic (NA) participants.

Results: The PCA content in the stratum corneum of ADPA subjects was significantly reduced versus that in NA subjects (median level, 67 vs 97 μg/mg protein [P = .028]). The ratio between cis- and trans-UCA decreased significantly from being highest in the NA group (1.62) to lowest in ADPA group (0.07 [P < .001 vs in the NA group; P = .006 vs in the ADPA group]), with the ADPA group having an intermediate cis/trans-UCA ratio (1.17 [P = .024 vs in the NA group]). The TEWL in ADPA subjects did not differ from that in the group with NA skin. Interestingly, ADPA 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 ADPA group had a decreased proportion of EOS-CERs (0.8 [P = .001] vs in the ADPA 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 ADPA group from the ADPA and NA groups.