Psoriasis (PSO) and Atopic dermatitis (AD) are common inflammatory skin diseases that affect people of all ages globally. They negatively impact the quality of life (QoL) of patients in health-related aspects such as physical, psychological and mental functioning. Here, we conducted a review of studies relating to candidate biomarkers and indicators associated with QoL impairment in PSO and AD. Data research was performed using PUBMED and SCOPUS databases from inception to September 2022. Most of the included studies reported genomic or proteomic biomarkers associated with disease activity and QoL outcomes. Sociodemographic, clinical and therapeutic factors have also been implicated in deterioration of life quality in these patients. The inclusion of clinical characteristics, QoL impairment and co-diagnosis should be considered in drug development programs, since processing biomarkers based on an increased number of features in addition to drug class and disease will intensify the value of the biomarker itself, thereby maximizing the future clinical utility as a stratification tool.

Background: Skin barrier disruption can be induced through experimental models, yet standardised comparisons are scarce. Transepidermal water loss (TEWL) and corneometry (CM) are established methods to quantify barrier impairment. Electrical impedance spectroscopy (EIS) is a novel approach, which may provide complementary information. Objectives: To compare EIS against TEWL and CM and to assess different barrier disruption models in humans in vivo. Methods: 15 healthy adults (7 female, 8 male; median age 27 years) were recruited. Experiment I compared 3 adhesive tapes for tape stripping (TS). Experiment II evaluated TS, 0.5% sodium lauryl sulphate (SLS), SLS + TS, and gluten using TEWL, EIS, and CM. Results: D‐Squame tape caused stronger barrier impairment than Scotch and Tesa (TEWL p < 0.01, EIS p < 0.05). SLS + TS induced the most (8 h: TEWL p < 0.001; EIS p < 0.05; CM p < 0.05) and persistent disruption (24 h: TEWL p < 0.05, EIS p < 0.05), followed by TS (8 h: TEWL p < 0.01; EIS p < 0.05). SLS and aqua caused minor, non‐significant effects; gluten had no measurable impact. EIS correlated strongly with TEWL ( ρ = −0.62, p < 0.0001) and CM ( ρ = −0.61, p < 0.0001). Conclusions: This first human study of EIS after experimental barrier disruption demonstrated strong concordance with TEWL and CM. Combined mechanical and chemical stress best reflects real‐life barrier insults and represents a potent model.

Sensitisation leading to food allergy may occur through the skin. Quantitative data on epidermal allergen penetration as a prerequisite for this remain limited. This study quantifies epidermal penetration of gluten and hydrolysed wheat protein (HWP) in 18 patients with challenge-confirmed WALDA (wheat allergy dependent on augmentation factors) and 12 healthy controls (HC). After 1 h of epicutaneous wheat application, 20 consecutive tape strips (TS) were collected, and wheat protein concentration was quantified by gliadin-specific ELISA. Skin barrier status was assessed by electrical impedance spectroscopy (EIS). Serum gliadin levels were measured before and 90 min after wheat application. Gliadin was detected across all TS layers for gluten and HWP. Penetration levels did not differ between patients and controls. Skin barrier status assessed by EIS did not differ significantly between individuals with and without a history of atopic dermatitis (p = 0.27). No correlation was observed between EIS-assessed skin barrier status and gliadin penetration. Serum gliadin was not increased after epicutaneous wheat application. This study using TS demonstrates for the first time that wheat allergens penetrated into the epidermis but could not be detected in the serum. Neither wheat allergy nor skin barrier status was associated with increased stratum corneum penetration. These findings suggest that epidermal uptake alone may not be sufficient to explain sensitisation.