INTRODUCTION
Acne is associated with inherent abnormalities in epidermal barrier, which may contribute to the process of comedogenesis and inflammation. Such dysfunctions occur in both the surface and follicular stratum corneum, and many current therapies used to treat acne vulgaris (AV) can cause further barrier dysfunction. Further, patient activities may worsen their stratum corneum (SC) impairment.1
Stratum Corneum Abnormalities
Acne vulgaris (AV) is associated with impaired water barrier function. In a cross sectional study comprising 36 patients with AV and 29 controls, Yamamoto et al. sought to identify the mechanism behind AV comedogenesis and its relationship with atypical follicular keratinization. The study determined an interrelationship between sebum secretion rate, lipid barrier function, and water barrier function of the stratum corneum (SC). It found that patients with moderate acne experienced sebum secretion and transepidermal water loss (TEWL) at increased rates when compared to the control population. Additionally, moderate acne patients had less hydration than the control group, and both moderate and mild acne patients had significantly less ceramides and percent free sphingosine than the control group. The study concluded that SC barrier dysfunction in AV is accompanied by hyperkeratosis of the follicular epithelium, and impaired skin barrier function in patients with facial acne is marked by a reduction of ceramides, which may be responsible for comedone formation.2The weather also has an impact on AV SC abnormalities. In a yearlong longitudinal study including adolescent male patients ages 13-18 in central New Jersey (7 with acne and 10 controls). Meyer et al. investigated potential seasonal differences in facial skin of acne patients.3 Average temperatures during this year were 18° F in January and 85° F in July.4 They looked at monthly evaluations of patients’ sebum production, TEWL, skin moisture, and bacterial population. Sebum production was increased in acne patients compared to controls (P<0.019) and displayed a seasonal variation with lowest production in winter. TEWL was higher in acne patients than in controls across the board and also showed a seasonal variation with an increase in colder weather (P=0.001). Skin moisture was higher in both groups in warmer weather (P≤0.016). Patients with acne had a higher recovery of both anaerobic and aerobic bacteria (P≤0.015), and fluorescence studies suggest P. acnes was increased in patients with acne. The study substantiated the differences in barrier function between patients with and without acne and displayed evidence for seasonality of this dysfunction.3
Role of Acne Therapy on Barrier Dysfunction
Topical acne therapies can have a negative impact on the skin barrier with the potential to increase dysfunction. Increased TEWL has been reported with benzoyl peroxide, tretinoin, and tazarotene. Appropriate vehicle choice and Improvements in vehicle technology have mitigated some of these problems. For example, creams versus gels, aqueous gels, microsphere formulations, micronization of actives, and the addition of humectants and emollients.5,6,7Benzoyl peroxide (BP) is a concentration-dependent irritant and is mildly keratolytic in nature. However, there is a paucity of data identifying the specific epidermal effects caused by BP. It is shown to increase TEWL by 1.8-fold and deplete stratum
