Supplementary Material for: Topical Applications of a Heparinoid-Containing Product Attenuate Glucocorticoid-Induced Alterations in Epidermal Permeability Barrier in Mice

<b><i>Introduction:</i></b> Either systemic or topical glucocorticoids (GCs) can cause significant adverse effects on cutaneous structure and function. Although some products and ingredients can improve GC-induced abnormalities in epidermal permeability barrier, the efficacy is moderate. Prior studies in normal mice showed that topical applications of a heparinoid-containing product, Hirudoid® cream, improve epidermal barrier function by upregulation of epidermal proliferation, expression of mRNA for epidermal differentiation, and lipid production. <b><i>Objective:</i></b> The objective of this study was to assess whether topical applications of this product could prevent GC-induced changes in epidermal function in murine skin. <b><i>Materials and Methods:</i></b> One group of C57BL/6J mice was treated topically with 0.05% clobetasol propionate twice daily for 6 days, while another group was treated topically with Hirudoid® cream 30 min after each application of clobetasol propionate. Untreated mice served as normal controls. Transepidermal water loss (TEWL) rates, stratum corneum hydration, and skin surface pH were measured using respective probes connected to an MPA5 physiology monitor. qPCR was used to measure the expression levels of mRNA for keratinocyte differentiation-related proteins and lipid synthetic enzymes. <b><i>Results:</i></b> Co-applications of Hirudoid® cream with GC minimally, but significantly, increased skin thickness in comparison to GC treatment alone (<i>p</i> &lt; 0.05), in parallel with increased expression levels of mRNA for PCNA in both the dermis and the epidermis. Moreover, Hirudoid® cream largely prevented GC-induced elevation in basal TEWL (<i>p</i> &lt; 0.001) and delay in barrier recovery (<i>p</i> &lt; 0.05), accompanied by upregulation in the expression levels of mRNA for epidermal involucrin, HMGCoA, and SPT1. However, both stratum corneum hydration and skin surface pH were comparable in the skin treated with GC alone versus GC + Hirudoid® cream. <b><i>Conclusion:</i></b> Topical heparinoid-containing product can partially prevent GC-induced alterations in some epidermal functions.