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Clinical Insights About the Role of Skin pH in Inflammatory Dermatological Conditions Introduction

December 2019 | Volume 18 | Issue 12 | Supplement Individual Articles | 212 | Copyright © December 2019


Leon H. Kircik

Icahn School of Medicine at Mount Sinai, New York, NY; Indiana Medical Center, Indianapolis, IN; Physicians Skin Care, PLLC, Louisville, KY; DermResearch, PLLC, Louisville, KY

Abstract
There was a time in the not so distant past that when we were asked about skin care, we would advise any patient to “use a moisturizer.” This meant going to the local drug store and purchasing one of just a few hand or body lotions then on the market. Many of these were heavily scented and featured ingredients that we now know could actually damage the skin barrier and paradoxically dry the skin.
There was a time in the not so distant past that when we were asked about skin care, we would advise any patient to “use a moisturizer.” This meant going to the local drug store and purchasing one of just a few hand or body lotions then on the market. Many of these were heavily scented and featured ingredients that we now know could actually damage the skin barrier and paradoxically dry the skin.

Thankfully, over the last few decades, the skin care market has evolved significantly; as has our understanding of the structure and function of the stratum corneum and, of course, its dysfunction. Today, we are lucky to have so many options. We even have disease-specific emollients and cleansers for several inflammatory conditions such as psoriasis, atopic dermatitis (AD), acne vulgaris (AV), and rosacea. The key is to use a skin care regimen either to support medical therapy or to maintain clearance and reduce flares by selecting products to meet the unique needs of individualized skin care in a cost-effective manner.

Several aspects of the stratum corneum must be optimized for healthy skin function: stratum corneum pH, filaggrin, pH-dependent lipid processing, serine proteases, and the skin microbiome. These factors are interrelated, and a deficit in one can have deleterious effects on the others.1-3 For example, in acne, disrupted barrier function leads to alterations in functional and ultrastructural properties of the skin. Coupled with inflammation and treatments such as topical retinoids, this imbalance may contribute to the risk of dry, irritated skin.4

Recently, attention has re-focused on the notion of the “acid mantle,” first described nine decades ago, and the critical importance of an appropriate skin pH. Imbalance in the skin pH can inhibit lipid processing and the function of filaggrin and can eventually lead to dysbiosis. Dysfunction of the skin microbiome, known as dysbiosis, is now recognized as an associated factor to AD flares and has been implicated in other dermatoses.5 In AV, pH imbalance is thought to directly influence impaired barrier function.4 As discussed in the pages ahead, there is now tantalizing evidence to suggest that supporting an appropriate skin pH vis-a-vis the use of appropriate topical cleansers and moisturizers may be an easy—and cost effective—but nonetheless fundamental component of the management of inflammatory skin diseases.

As detailed in this supplement, consensus panels of experts in AD and in AV agree that cleansers and moisturizers close to physiologic skin surface pH (4.0–6.0) may support skin barrier repair, decreased inflammation, accelerated pH recovery, and increased antimicrobial defense. In acne, use of such products may not only improve skin barrier function but also enhance treatment tolerability. Despite the importance of Leon H. Kircik MDmaintaining a healthy skin pH, many mass-market cleansers and lotions have a high pH (which is not disclosed on the label) and may further damage the fragile skin barrier in diseased skin. This may be true even for more expensive formulations and for some of those marketed specifically to patients with atopic dermatitis and acne vulgaris. We should now think about the pH of products when making recommendations to our patients. Consider the unique formulation of CeraVe® Hydrating Facial cleanser, which has the closest pH (5.5) to acid mantle of all the cleansers in the market.

We also need to consider that ingredients such as ceramides, widely available and advertised in several formulations, actually do penetrate the stratum corneum and get where they need to get in the skin to make a difference. This is where CeraVe‘s unique Multi Vesicular Emulsion (MVE) technology, which has a multilamellar series of concentric spheres of oil and water phases, makes a huge difference compared to traditional emulsions. MVE traps ingredients into layers and dissolves slowly layer by layer into the skin over a sustained period of time, and can carry large molecules such as ceramides and hyaluronic acid. MVE enables CeraVe® moisturizing cream to deliver moisture to the skin continuously over 24 hours.

Recognizing the critical importance of appropriate skin care, dermatology providers are reminded of the need to educate AD and AV patients on the selection and use of cleansers and moisturizers that may enhance tolerability of treatment and support optimum barrier function. We should be prepared to direct our patients to products in the crowded drug store aisles that are formulated at the proper pH with beneficial ingredients that actually penetrate the stratum corneum appropriately, and that lack concerning ingredients like fragrances and preservatives.

As products have grown more sophisticated, with significant potential benefits for patients, then so must our product recommendations go beyond the simple advice to “use a moisturizer.”

DISCLOSURE
Dr Kircik has received compensation from JDD for his editorial services. Dr Kircik has served either as an investigator, consultant, or speaker for L’Oreal. Dr Kircik is President of the International Dermatology Education Foundation.

REFERENCES
  1. Bandier J, Johansen JD, Petersen LJ, Carlsen BC. Skin pH, atopic dermatitis, and filaggrin mutations. Dermatitis. 2014;25(3):127-9.
  2. Garidel P, Folting B, Schaller I, Kerth A. The microstructure of the stratum corneum lipid barrier: mid-infrared spectroscopic studies of hydrated ceramide:palmitic acid:cholesterol model systems. Biophys Chem. 2010;150(1-3):144-56.
  3. Miajlovic H, Fallon PG, Irvine AD, Foster TJ. Effect of filaggrin breakdown products on growth of and protein expression by Staphylococcus aureus. J Allergy Clin Immunol Pract. 2010;126(6):1184-90.e3.
  4. Thiboutot D, Del Rosso JQ. Acne Vulgaris and the epidermal barrier: Is acne vulgaris associated with inherent epidermal abnormalities that cause impairment of barrier functions? Do any topical acne therapies alter the structural and/or functional integrity of the epidermal barrier? J Clin Aesthet Dermatol. 2013;6(2):18-24.
  5. Kong HH, Oh J, Deming C, Conlan S, Grice EA, Beatson MA, et al. Temporal shifts in the skin microbiome associated with disease flares and treatment in children with atopic dermatitis. Genome Res. 2012;22(5):850-9.