Blockade of interleukin-13 signalling improves skin barrier function and biology in patients with moderate-to-severe atopic dermatitis.

BACKGROUND: Interleukin (IL)-13 is a key driver of inflammation and barrier dysfunction in atopic dermatitis (AD). While there is robust evidence that tralokinumab - a monoclonal antibody that neutralizes IL-13 - reduces inflammation and clinical disease activity, less is known about its effects on barrier function. OBJECTIVES: To characterize the effects of tralokinumab treatment on skin barrier function. METHODS: Transepidermal water loss (TEWL), stratum corneum hydration (SCH), natural moisturizing factor content, histopathological characteristics, biomarker expression and microbiome composition were evaluated in lesional, nonlesional and sodium lauryl sulfate-irritated skin of 16 patients with AD over the course of 16 weeks of tralokinumab treatment. RESULTS: All clinical severity scores decreased significantly over time. At week 16, mean TEWL in target lesions decreased by 33% (P = 0.01) and SCH increased by 58% (P = 0.004), along with a histological reduction in spongiosis (P = 0.003), keratin 16 expression and epidermal thickness (P = 0.001). In parallel, there was a significant decrease in several barrier dysfunction-associated and proinflammatory proteins such as fibronectin (P = 0.006), CCL17/TARC (P = 0.03) and IL-8 (P = 0.01), with significant changes seen as early as week 8. Total bacterial load and Staphylococcus aureus abundance were significantly reduced from week 2. CONCLUSIONS: Tralokinumab treatment improved skin physiology, epidermal pathology and dysbiosis, further highlighting the pleiotropic role of IL-13 in AD pathogenesis.

Atopic dermatitis (AD) is a common chronic inflammatory skin disease characterized by a marked skin barrier impairment. The skin barrier deficiency is characterized by an imbalance of organisms naturally found on the skin, including a reduction in the diversity of organisms and an increased amount of bacteria called Staphylococcus aureus. Further, there are reduced structural proteins, problems with 'tight junctions' (which maintain skin integrity) and abnormalities in the make-up/organization of skin lipids. As a result, the skin cannot keep itself hydrated or moisturized, and there is an increased likelihood of 'irritant contact dermatitis' (for example, rashes, dry skin and itching). 'Interleukin (IL)-13' is a signalling protein found in the immune system that is increased in AD and causes inflammation. Tralokinumab is a drug that neutralizes IL-13 and reduces inflammation and the severity of AD; however, less is known about its effect on the skin barrier. This study aimed to investigate the effects of tralokinumab on skin barrier function by looking at levels of water loss, hydration, natural moisturizing factor content, histopathological characteristics (how it looks under a microscope), the expression of biomarkers (indicators of a particular condition) and composition of the microbiome (organisms living together) in the upper skin layer of 16 people with AD who were treated with tralokinumab for 16 weeks. We found that blocking IL-13 leads to a better skin barrier with less water loss and better hydration, as well as the normalization of skin bacteria. The skin was also less irritable, and its microscopic appearance was similar to normal skin after 16 weeks of treatment. Finally, the drug appeared to be effective and safe. Overall, our findings suggest that by neutralizing IL-13, tralokinumab could help to restore the skin barrier function of people with AD.

Stratum corneum and microbial biomarkers precede and characterize childhood atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is the most common paediatric inflammatory skin disease. There are currently no robust biomarkers that could reliably predict its manifestation, and on the molecular level, it is less well characterized than adult AD. OBJECTIVES: This study aimed to extend previous findings and provide evidence for distinct changes of the epidermal proteome and microbiome preceding the onset of AD as well as characterizing early AD. METHODS: We longitudinally analysed epidermal biomarker levels and microbial profiles in a cohort of 50 neonates at high risk for AD, who had participated in a randomized controlled trial on early emollient use for AD prevention. RESULTS: About 26% of the infants developed AD until month 24 with an average age of 10 month at disease onset. In children with later AD, IL-1Ra, TNFß, IL-8, IL-18, IL-22, CCL2, TARC, TSLP and VEGFa showed increased levels prior to disease manifestation with levels of IL-1Ra, TNFß and VEGFa already increased shortly after birth. Further, children with later AD displayed a delayed maturation and differentially composed skin microbiome prior to AD onset. At manifestation, levels of multiple Th2, Th17/22 and Th1-associated biomarkers as well as innate immunity markers were elevated, and abundances of commensal Streptococcus species were reduced in favour of Staphylococcus epidermidis. CONCLUSIONS: Our results indicate that elevations of proinflammatory stratum corneum biomarkers and alterations of the skin microbiome precede paediatric AD and characterize the disease at onset.