Heparinoid Cream Restores Epidermal Barrier Homeostasis and Attenuates Type 2 Inflammation in MC903-Induced Dermatitis

Epidermal barrier dysfunction and cutaneous inflammation are closely interconnected in inflammatory skin diseases. However, the molecular effects of heparinoid cream on inflamed skin remain incompletely understood. In this study, we investigated the effects of heparinoid cream on epidermal barrier homeostasis and cutaneous inflammation using an MC903-induced dermatitis model. Eight-week-old female BALB/c mice were treated topically with MC903 for 7 consecutive days, with or without concomitant application of heparinoid cream. Skin barrier function, histological changes, inflammatory markers, and gene expression were evaluated by transepidermal water loss measurements, histology, immunohistochemistry, quantitative PCR, and RNA sequencing. Therapeutic effects were also assessed by applying heparinoid cream after dermatitis had been established. RNA sequencing identified 816 differentially expressed genes following heparinoid cream treatment, including 146 upregulated and 670 downregulated genes. Upregulated genes were enriched in epidermal differentiation- and barrier-related pathways, whereas downregulated genes were enriched in immune and inflammatory pathways. Heparinoid cream significantly reduced transepidermal water loss and epidermal thickness, suppressed Il13 and Tslp expression, and reduced epidermal KLK5 and TSLP expression. In parallel, expression of multiple epidermal differentiation- and barrier-associated genes, including members of the Lce family, Flg, and Flg2, was restored. Therapeutic application of heparinoid cream after establishment of dermatitis was also associated with improved barrier function, increased Flg expression, reduced Tslp mRNA expression, and decreased epidermal KLK5 and TSLP immunohistochemical staining. Secondary reanalysis of a previously published human keratinocyte RNA-seq dataset revealed changes in selected barrier- and innate immunity-associated genes following MPS treatment under non-inflammatory monolayer culture conditions. These findings demonstrate that heparinoid cream treatment is associated with concurrent improvements in epidermal barrier-related parameters and attenuation of type 2 inflammatory responses in MC903-induced dermatitis. These findings provide molecular insights into the changes associated with topical application of a heparinoid-containing formulation in inflamed skin, although the specific contribution of MPS remains to be established.