Acta Dermato-Venereologica 99-13CompleteContent | Page 7

1201 REVIEW ARTICLE Skin Barrier Damage and Itch: Review of Mechanisms, Topical Management and Future Directions Gil YOSIPOVITCH 1 , Laurent MISERY 2 , Ehrhardt PROKSCH 3 , Martin METZ 4 , Sonja STÄNDER 5 and Martin SCHMELZ 6 1 Dr. Phillip Frost Department of Dermatology and Itch Center, University of Miami, Miami, FL, USA, 2 Department of Dermatology and French Expert Center on Itch, University of West Brittany, Brest, France, 3 Department of Dermatology, University of Kiel, Kiel, 4 Department of Dermatology and Allergy, Charité-Universitätsmedizin Berlin, Berlin, 5 Department of Dermatology, Centre for Chronic Pruritus, University of Münster, Münster, and 6 Department of Experimental Pain Research, University of Heidelberg, Mannheim, Germany Barrier damage, dry skin and itch are intricately linked and form the basis of many common skin diseases. Da­ mage from environmental insults, or genetic or inflam­ matory causes, can impair the skin barrier, resulting in an increase in transepidermal water loss and activa­ tion of itch-associated nerve fibres. The itch–scratch cycle can perpetuate skin barrier damage and itch. To­ pical therapeutic strategies are utilised to overcome dry skin and itch, primarily in the form of emollients. Recent advances in our understanding of the mecha­ nisms underlying itch have enabled the development of new topical therapies, which may be incorporated into existing treatment regimes. Ultimately, treatment of dry skin and itch must be highly tailored to the indi­ vidual according to their needs. Key words: pruritus; dry skin; skin barrier; emollients. Accepted Aug 22, 2019; E-published Aug 22, 2019 Acta Derm Venereol 2019; 99: 1201–1209. Corr: Gil Yosipovitch MD, Dr. Phillip Frost Department of Dermatology, Miller School of Medicine University of Miami, 1600 NW 10th Ave RMSB 2067B Miami FL 33136, USA. E-mail: [email protected] M any chronic skin disorders, such as atopic der- matitis (AD) and psoriasis, are associated with impaired skin barrier function (1–3). The skin barrier prevents the entry of harmful agents, such as antigens and infectious microorganisms, and prevents moisture loss (2–4). Impaired barrier function has been linked to dry, itchy skin characterised by redness, flakes, cracks and a rough texture (“outside-in”), but epidermal inflam- mation can also weaken the barrier (“inside-out”) (5, 6). Pruritus, an important feature of many dermatoses with impaired skin barrier function, is a sensation that drives the urge to scratch and can severely affect quality of life (QoL) and psychosocial wellbeing (7–9). Itch in- tensity has been associated with stress and negative life events, and can place a burden on patients’ day-to-day activities (10). The underlying dermatoses associated with dry skin (xerosis) and itch can differ between patient populations (11, 12). Structural and physiological changes in the skin barrier occur with age and, when combined with comorbidities and polypharmacy, lead to an increased SIGNIFICANCE Itch is a common symptom of many skin barrier-related dermatoses and can severely impact quality of life. How­ ever, there are a limited number of effective anti-itch topi- cal therapies currently available and several unmet needs not addressed by current itch management strategies. As our knowledge of the mechanisms underlying itch has im- proved, several novel therapies have recently emerged that can be incorporated into existing regimens to enhance itch therapy and management. Here, we summarise research and current opinion on available topical therapies and give recommendations for the optimal management of itch. incidence of barrier abnormalities among the elderly (11, 12). Xerosis is the most common cause of skin barrier- related pruritus in this population and has been reported in 69% of elderly chronic itch patients (13, 14). However, in children and adults, one of the most common causes of pruritus is AD (15), a chronic inflammatory disorder in which patients experience itch with high intensity (16). Itch can place a heavy burden on QoL, with AD having a profoundly negative impact on those afflicted and their families (17). Topical therapy is the backbone of treatment for skin barrier-related pruritus and includes emollients, corticosteroids, immunomodulators, capsaicin, local anaesthetics and antihistamines (18). As our knowledge of the mechanisms underlying the sensation of itch have improved, several novel antipruritic therapies have emer- ged. This review aims to summarise the advantages and disadvantages of current and emerging topical therapies to treat dry skin and itch and highlight considerations to be made when choosing an appropriate therapy. Finally, we will discuss unmet needs in itch therapy. For this review article, a PubMed search was perfor- med using various search terms, with studies selected based on their scientific rigor and the strength of their results. Selected studies were compared and summarised according to existing theories and mechanistic models, in addition to the experience of the authors, who are key opinion leaders in the fields of itch and skin barrier function. Conclusions were made on a qualitative, rather than quantitative, basis. This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica. doi: 10.2340/00015555-3296 Acta Derm Venereol 2019; 99: 1201–1209