An evidence-based, peer-reviewed journal for practicing clinicians in the field of dermatology
Issue link: http://jcadonline.epubxp.com/i/665695
S6 SUPPLEMENT TO THE JOURNAL OF CLINICAL AND AESTHETIC DERMATOLOGY [APRIL 2016 • VOLUME 9 • NUMBER 4 • SUPPLEMENT 1] • The major structural and physiochemical differences in African American skin when compared to Caucasian skin in the SC and parameters that assess EB function are 1) increased number of cell layers and resistance to tape stripping despite equal thickness, 2) increased SC lipid content with a decrease in ceramides, 3) increased electrical resistance, 4) increased desquamation, and 5) more rapid barrier recovering after SC tape stripping. 33,37 • Using an imaging technique for skin capacitance, xerosis was greater on sun-exposed forearm sites from women with lighter skin tones (Chinese, Caucasian) than on primarily sun-protected sites; no differences are seen among sites from women with darker skin (African American, Mexican). Xerosis did not change as a function of ethnicity for the younger group regardless of forearm sites tested. With increasing age, xerosis was higher for African American and Caucasian women than for Chinese and Mexican women, with a higher percentage increase in Caucasian women. 34 • In healthy Asian (n=25), African (n=18), and Caucasian skin (n=28), ceramide∕cholesterol ratios were statistically significantly different between groups. Asians had the highest ratio as compared with both white and African skin (P<0.001); African skin exhibited the lowest ratio values. No statistically significant differences were noted between any of the ceramide subgroups. 35 • In a study evaluating SC pH, permeability barrier homeostasis, and SC integrity in three geographically disparate populations comparing outcomes with Fitzpatrick Skin Type (FST) I–II versus FST IV–V skin, FST I V–V subjects showed 1) lower surface pH, 2) enhanced SC integrity (based on TEWL changes with sequential tape strippings), and 3) more rapid barrier recovery than FST I–II subjects. Enhanced barrier function could be ascribed to increased epidermal lipid content, increased lamellar body production, and reduced acidity, leading to enhanced lipid processing. Compromised SC integrity in FST I–II subjects could be ascribed to increased serine protease activity leading to greater corneo-desmosome degradation. Adjust- ment of SC pH in FST I–II SC to levels seen with FST IV–V SC improved EB function. These outcomes support marked pigment- type differences in epidermal structure and function that are pH driven. 38 • SC impairment in Caucasian skin initially appeared to be more severely affected by SLS-induced epidermal damage than African American skin. However, after 24 hours, the TEWL level of Caucasian skin did recover to levels comparable with those of African American skin. A limitation of this study noted by the authors is small sample size. 39 More data are needed on differences in SC/EB structure and function among individuals of different races, ethnicities, and different magnitudes of skin pigmentation (FST). A summary of findings gleaned to date depicts relative differences based on an overall consensus from available literature. 31 Racial variability in physiological properties of the SC and EB can directly impact SC water content and sensitivity to exogenously applied agents. Given the large number of moisturizers presently available in the marketplace, several different moisturizer/barrier repair formulations with individual ingredients may be employed to promote skin hydration. More data are needed to determine if certain moisturizers/barrier repair formulations may be more or less effective than others to maintain SC/EB structure and function and to manage xerotic skin disorders. 31 Is the Use of Moisturizer/Barrier Repair Formulations Relevant in Clinical Practice? There is a body of evidence to show that optimal management of many skin diseases, including eczematous dermatitis, acne vulgaris, rosacea, psoriasis, and xerosis, includes appropriate skin care. 3,23–30 Incorporation of a gentle (nonirritating) skin cleanser and a well-designed Figure 4. Stepwise progression from damage to permeability barrier xerosis eczematous dermatitis. Reprinted with permission from: Del Rosso JQ, Levin J. J Clin Aesthet Dermatol. 2011;4(9): 22–42. © 2011 Matrix Medical Communications.