INTERLEUKIN-19 (IL-19) may contribute to atopic dermatitis (AD) by impairing epidermal barrier function and amplifying type 2 inflammation, according to findings integrating patient samples, clinical transcriptomic data, animal models, and cellular experiments.
The study investigated the role of IL-19 across several experimental settings. Serum samples from patients with AD were analysed alongside transcriptomic data from clinical AD lesions. Researchers also used an AD-like mouse model with either exogenous IL-19 supplementation or IL-19 gene knockout, as well as in vitro cellular models.
Serum IL-19 levels correlated with disease severity after adjustment for clinical covariates and type 2 cytokines in the study cohort, supporting an association between IL-19 activity and AD severity.
In an MC903-induced AD-like mouse model, supplementation with IL-19 exacerbated the dermatitis phenotype, whereas IL-19 gene knockout alleviated disease manifestations.
Mechanistic experiments identified keratinocytes as the primary source of IL-19 within AD lesions. Exposure to house dust mites increased IL-19 expression in keratinocytes in vitro, suggesting that these cells may contribute to local IL-19 activity within affected skin.
IL-19 acted through the STAT6/STAT3 signalling pathway to suppress expression of loricrin and keratin-10. These changes may impair epidermal barrier function, providing a potential mechanism through which IL-19 contributes to AD pathology.
Alongside its effects on epidermal barrier components, IL-19 increased expression of thymic stromal lymphopoietin and IL-33. These changes may facilitate the type 2 inflammatory cascade associated with AD.
The experiments also indicated that IL-19 may additively exacerbate inflammatory responses in the presence of IL-13 and IL-4, suggesting that its activity could interact with established type 2 inflammatory pathways.
Together, the findings support IL-19 as a pro-inflammatory mediator with potential roles in both epidermal barrier dysfunction and type 2 immune dysregulation. The results suggest that IL-19 could represent a potential therapeutic target for addressing these interconnected mechanisms in AD, although the findings are based on integrated clinical, animal, and cellular models.
Reference
Mu T et al. IL-19 exacerbates atopic dermatitis by disrupting epidermal barrier function and amplifying type 2 inflammation. Inflammation. 2026; DOI: 10.1007/s10753-026-02587-3.
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