Dupilumab significantly improves skin barrier function in patients with moderate-to-severe atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is characterized by abnormal skin lipids that are largely driven by hyperactivated type 2 immune responses. The antibody to the α-subunit of interleukin (IL)-4 receptor, dupilumab, was recently approved to treat AD and demonstrated strong efficacy. However, the role of dupilumab therapy in the regulation of skin barrier structure and function has not been fully explored. METHODS: We have evaluated the content of lipids and transepidermal water loss (TEWL) in lesional and non-lesional skin of adults and adolescents with moderate-to-severe AD over the course of 16-week treatment with dupilumab and compared those values with that of matched healthy volunteers. RESULTS: Dupilumab treatment provided a significant decrease in TEWL in AD lesions, lowering it almost to the levels seen in the skin of healthy subjects. Blocking IL-4/IL-13 signaling with dupilumab normalized lipid composition (decreased levels of ceramides with non-hydroxy fatty acids and C18-sphingosine and increased the level of esterified omega-hydroxy fatty acid-containing ceramides) and increased ceramide chain length in lesional as well as non-lesional stratum corneum of AD patients. Partial changes for these parameters were already observed after 2 weeks, with a full response achieved after 8 weeks of dupilumab treatment. CONCLUSIONS: Inhibition of IL-4/IL-13 signaling by dupilumab allows restoration of skin lipid composition and barrier function in patients with moderate-to-severe AD.

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 (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 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 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.

Dupilumab Inhibits Vascular Leakage of Blood Proteins Into Atopic Dermatitis Skin.

BACKGROUND: Atopic dermatitis (AD) skin lesions are associated with oozing, bleeding, and erythema. This suggests that AD is associated with vascular changes. Dupilumab is an antibody to the alpha subunit of IL-4 receptor that demonstrates strong efficacy in the treatment of AD. IL-4 is known to reduce the permeability barrier function of vascular endothelium. OBJECTIVE: To examine the effects of dupilumab on vascular barrier function in AD skin. METHODS: Using proteomic analysis, we evaluated the plasma protein composition in skin tapes of lesional and nonlesional skin of adults and adolescents with moderate to severe AD over the course of a 16-week treatment with dupilumab and compared those with matched healthy subjects. RESULTS: At baseline, 115 plasma proteins were detected in AD skin and globally increased (1.5-fold or greater) compared with healthy skin. Functionally, these proteins included immunoglobulins, proteins involved in the coagulation process, enzymes, protease inhibitors, transport proteins, acute-phase proteins, complement proteins, and other pleiotropic proteins. Noteworthy, fibrinogens, fibronectin, and heme-binding proteins haptoglobin and hemopexin were among the top proteins originating from plasma and were increased in AD lesional versus healthy skin at baseline (P < .0001). Dupilumab treatment resulted in significantly reduced levels of plasma proteins in AD skin (P < .0001), with most dropping to levels seen in healthy skin or no longer detectable at week 16. CONCLUSIONS: Inhibition of IL-4/IL-13 action by dupilumab significantly reduces the efflux of plasma proteins into AD skin. Several of these proteins, such as fibrinogens and fibronectin, are known to enhance Staphylococcus aureus colonization and are associated with AD skin severity.

Development of a human skin commensal microbe for bacteriotherapy of atopic dermatitis and use in a phase 1 randomized clinical trial.

Staphylococcus aureus colonizes patients with atopic dermatitis (AD) and exacerbates disease by promoting inflammation. The present study investigated the safety and mechanisms of action of Staphylococcus hominis A9 (ShA9), a bacterium isolated from healthy human skin, as a topical therapy for AD. ShA9 killed S. aureus on the skin of mice and inhibited expression of a toxin from S. aureus (psmα) that promotes inflammation. A first-in-human, phase 1, double-blinded, randomized 1-week trial of topical ShA9 or vehicle on the forearm skin of 54 adults with S. aureus-positive AD (NCT03151148) met its primary endpoint of safety, and participants receiving ShA9 had fewer adverse events associated with AD. Eczema severity was not significantly different when evaluated in all participants treated with ShA9 but a significant decrease in S. aureus and increased ShA9 DNA were seen and met secondary endpoints. Some S. aureus strains on participants were not directly killed by ShA9, but expression of mRNA for psmα was inhibited in all strains. Improvement in local eczema severity was suggested by post-hoc analysis of participants with S. aureus directly killed by ShA9. These observations demonstrate the safety and potential benefits of bacteriotherapy for AD.

The nonlesional skin surface distinguishes atopic dermatitis with food allergy as a unique endotype.

Skin barrier dysfunction has been reported in both atopic dermatitis (AD) and food allergy (FA). However, only one-third of patients with AD have FA. The purpose of this study was to use a minimally invasive skin tape strip sampling method and a multiomics approach to determine whether children with AD and FA (AD FA+) have stratum corneum (SC) abnormalities that distinguish them from AD without FA (AD FA-) and nonatopic (NA) controls. Transepidermal water loss was found to be increased in AD FA+. Filaggrin and the proportion of ω-hydroxy fatty acid sphingosine ceramide content in nonlesional skin of children with AD FA+ were substantially lower than in AD FA- and NA skin. These abnormalities correlated with morphologic changes in epidermal lamellar bilayer architecture responsible for barrier homeostasis. Shotgun metagenomic studies revealed that the nonlesional skin of AD FA+ had increased abundance of Staphylococcus aureus compared to NA. Increased expression of keratins 5, 14, and 16 indicative of hyperproliferative keratinocytes was observed in the SC of AD FA+. The skin transcriptome of AD FA+ had increased gene expression for dendritic cells and type 2 immune pathways. A network analysis revealed keratins 5, 14, and 16 were positively correlated with AD FA+, whereas filaggrin breakdown products were negatively correlated with AD FA+. These data suggest that the most superficial compartment of nonlesional skin in AD FA+ has unique properties associated with an immature skin barrier and type 2 immune activation.