Stratum Corneum Hydration As a Potential Marker of Response to Dupilumab in Atopic Dermatitis®: A Prospective Observational Study

Skin Barrier Function and Microtopography in Patients with Atopic Dermatitis

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease whose incidence is increasing. Skin barrier dysfunction plays an important role in this disease. It has been observed that AD patients have higher transepidermal water loss (TEWL) and lower stratum corneum hydration (SCH); however, there is little information about skin microtopography in this pathology. The objective of this study is to evaluate skin barrier dysfunction and structural changes in patients with AD. Methods: A cross-sectional study was conducted including patients with AD. Parameters of skin barrier function were measured (TEWL, temperature, erythema, pH, skin hydration, elasticity) and also other topographical parameters (scaliness, wrinkles, smoothness, surface, contrast, variance) in both healthy skin and flexural eczematous lesions. Results: A total of 32 patients with AD were included in the study. Flexural eczematous lesions had higher erythema (369.12 arbitrary unit (AU) vs. 223.89 AU, p < 0.001), higher TEWL (27.24 g/h/m2 vs. 13.51 g/h/m2, p < 0.001), lower SCH (20.3 AU vs. 31.88 AU, p < 0.001) and lower elasticity (0.56% vs. 0.65%, p = 0.05). Regarding topographic parameters, flexural eczematous lesions presented greater scaliness (5.57 SEsc vs. 0.29 SEsc, p = 0.02), greater smoothness (316.98 SEsm vs. 220.95 SEsm p < 0.001), more wrinkles (73.33 SEw vs. 62.15 SEw p = 0.03), greater surface area (836.14% vs. 696.31%. p < 0.001), greater contrast (2.02 AU vs. 1.31 AU p = 0.01), greater variance (6.22 AU vs. 4.96 AU p < 0.001) and a lower number of cells (105.5 vs. 132.5 p < 0.001) compared to unaffected healthy skin, reflecting a decrease in skin quality in AD patients. Conclusions: Both skin barrier function and skin topography are damaged in patients with AD, with differences between healthy skin and flexural eczema.

Intraday Variations in Skin Water Parameters

INTRODUCTION

Three interrelated skin water assessments include stratum corneum hydration (SCH) via electrical measurements, skin water using tissue dielectric constant (TDC) measurements, and transepidermal water loss (TEWL). These are differentially used for skin physiology research, clinical assessments of dermatological conditions and to assess skin water in diabetes and lymphedema. Often volar forearm skin is used for assessments done at various times of day (TOD). The present goal was to assess the extent of intraday variability in SCH, TDC, and TEWL.

METHODS

Twelve medical students self-measured SCH, TDC, and TEWL on their forearm every 2 h from 08:00 to 24:00 h on 2 consecutive days. All participants were well trained and pre-certified in all procedures. Tests for parameter differences among TOD were via the nonparametric Friedman test.

RESULTS

No significant differences in SCH or TEWL were found among TOD over the 16-h interval for either day or combined. Contrastingly, TDC decreased slightly but significantly from morning through evening. There was no evidence of a diurnal pattern. Interestingly, a significant nonlinear relationship between TEWL and SCH was detected.

CONCLUSION

Findings indicate only minor intraday variations with TOD trend except for TDC which decreases slightly from morning through evening. The clinical relevance relates to the confidence now gained associated with the parameter estimates when measured at different TOD during normal clinic hours or beyond. This should help in estimating the potential importance of small differences if measured at a different TOD. From a physiological viewpoint, the findings uncover and describe an interesting nonlinear relationship between TEWL and SCH which may serve to propel further investigations that might better characterize this process.

Restoration of Skin Barrier Abnormalities with IL4/13 Inhibitors and Jak Inhibitors in Atopic Dermatitis: A Systematic Review

Background and Objectives: Atopic dermatitis is a chronic inflammatory skin disorder with a significant burden on patients' quality of life. This systematic review aims to evaluate the restoration of skin barrier abnormalities with interleukin-4/interleukin-13 (IL-4/IL-13) inhibitors and Janus kinase (JAK) inhibitors in atopic dermatitis. Materials and Methods: A comprehensive review of the literature was conducted, focusing on studies that assess the use of IL-4/IL-13 inhibitors and JAK inhibitors for atopic dermatitis. We identified eligible studies by searching Medline via PubMed with a special focus on their effect on the restoration of the epidermal barrier. Included studies evaluated the transepidermal water loss (TEWL), the reduction in epidermal thickness (ET), the improvement in ceramide synthesis, and the increase in stratum corneum hydration (SCH) with IL-4/IL-13 inhibitors and JAK inhibitors. The quality of included studies was assessed using the ROBINS-I and the RoB 2.0 tool for assessing the risk of bias. Results: Ten of the included studies concern dupilumab, while two concern JAK inhibitors. Ten were observational studies and two were randomized controlled trials (RCTs). The total number of included participants was 378 concerning dupilumab and 38 concerning JAK inhibitors. Five studies did not include any comparison group, three included healthy volunteers, two were conducted versus placebo, and two compared dupilumab with other treatments. The follow-up period ranged between 29 days and 32 weeks. The results demonstrated a significant decrease in transepidermal water loss (TEWL) and an increase in SCH on eczematous lesions for patients with sustained response to dupilumab treatment and observed improvements in ET and filaggrin (FLG) staining, which further support the efficacy of JAK inhibitors in enhancing skin barrier function. Conclusions: This review underscores the efficacy of IL-4/IL-13 inhibitors in improving skin barrier function. However, the limited number of studies focusing on JAK inhibitors and the overall lack of RCTs highlight the need for further research to establish the definitive role of IL-4/IL-13 inhibitors and JAK inhibitors in the restoration of the skin barrier.

Transepidermal Water Loss and T-helper 2 (Th2)-Associated Inflammatory Markers in Two Pediatric Patients During the First Four Weeks of Treatment With the Oral Janus Kinase Inhibitor Upadacitinib

Few studies have evaluated the effects of upadacitinib on skin barrier function and T-helper 2 (Th2)-associated inflammatory biomarkers in severe atopic dermatitis (AD). In this study, we followed two pediatric patients with AD who had previously failed to respond to conventional treatment and measured their serum Th2-associated chemokine thymus and activation-regulated chemokine (TARC) and serine protease inhibitor squamous cell carcinoma antigen (SCCA) 2 levels and transepidermal water loss (TEWL) during the first four weeks of upadacitinib treatment. Both patients showed marked clinical improvement and decreased TEWL, blood eosinophil counts, and serum TARC and SCCA2 levels after four weeks of upadacitinib treatment. These findings suggest that upadacitinib attenuates Th2-associated inflammatory markers and promotes skin barrier integrity.