INTRODUCTION
Psoriasis, a chronic inflammatory disease characterized by erythematous and scaly skin, is caused by hyperproliferation and differentiation of keratinocytes, which results in dysregulation of the skin barrier.1,2 Typically, a healthy stratum corneum consists of corneocytes and a lipid-rich extracellular matrix organized in a brick-and-mortar arrangement.3 Ceramides, cholesterol, and free fatty acids predominantly populate the extracellular matrix and contribute to maintenance of barrier homeostasis and hydration.4,5 However, in patients with psoriasis, the stratum corneum becomes depleted of lipids, including ceramides, resulting in disrupted skin barrier function, elevated levels of transepidermal water loss (TEWL), and reduced stratum corneum hydration.2,5,6 Notably, depletion of stratum corneum lipids in psoriasis is thought to be limited to lesional epidermis and may potentiate inflammation associated with psoriasis.5,7
As such, direct restoration of the skin barrier is crucial for patients with psoriasis and may be facilitated by using moisturizers. Some moisturizers (eg, emollients) promote retention of hydration in the stratum corneum, reduce TEWL, and normalize hyperproliferation and differentiation of keratinocytes, thereby supporting skin barrier function in patients with psoriasis.8 Furthermore, moisturizers that contain lipids such as ceramides may further assist in skin barrier repair by supplementing the aforementioned "mortar" of the stratum corneum and increasing total skin ceramide content.5,9 Indeed, the American Academy of Dermatology and National Psoriasis Foundation joint guidelines recommend the use of moisturizers (ie, creams, ointments, lotions, and gels) as adjuvant therapy for topical corticosteroids to help reduce itch and desquamation.8 Despite the widespread use of moisturizers in psoriasis regimens, there is still a need to evaluate the order of application with moisturizers and prescription therapies regardless of the therapeutic agent selected.10-13
As such, direct restoration of the skin barrier is crucial for patients with psoriasis and may be facilitated by using moisturizers. Some moisturizers (eg, emollients) promote retention of hydration in the stratum corneum, reduce TEWL, and normalize hyperproliferation and differentiation of keratinocytes, thereby supporting skin barrier function in patients with psoriasis.8 Furthermore, moisturizers that contain lipids such as ceramides may further assist in skin barrier repair by supplementing the aforementioned "mortar" of the stratum corneum and increasing total skin ceramide content.5,9 Indeed, the American Academy of Dermatology and National Psoriasis Foundation joint guidelines recommend the use of moisturizers (ie, creams, ointments, lotions, and gels) as adjuvant therapy for topical corticosteroids to help reduce itch and desquamation.8 Despite the widespread use of moisturizers in psoriasis regimens, there is still a need to evaluate the order of application with moisturizers and prescription therapies regardless of the therapeutic agent selected.10-13
