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From "Saran Wrap" to Current Understanding of the Cutaneous Barrier
( Peter M. Elias ),( Joan S. Wakefield ) 한국피부장벽학회 2011 한국피부장벽학회지 Vol.13 No.1
This short article reviews key milestones and insights that led to our current concept of the permeability barrier. In the 1960`s, the stratum corneum (SC) was considered an inconsequential layer of desquamating cells. Then came the realization that the SC is highly resilient, followed by the appreciation of its unique twocompartment organization, with lipids segregated within intracellular domains. Now, we view the SC as a metabolically-active tissue that self-regulates desquamation, and as a biosensor that signals metabolic responses in the underlying epidermis in response to environmental alterations. However, the permeability barrier is but one of a set of co-regulated and interdependent defensive functions that is mediated by this unique, protective tissue. Finally, genetic mutations and acquired insults that lead to pathophysiologic processes provoke not only ichthyosis, but also downstream inflammation, the so-called ``outside-to-inside`` view of the pathogenesis of inflammatory dermatoses. Accordingly, next-generation therapy for these disorders should be directed at correcting the primary barrier abnormality, rather than interdicting downstream inflammation, which should result in a large improvement in specificity, efficacy and safety.
Therapeutic Implications of a Barrier-based Pathogenesis of Atopic Dermatitis
( Peter M. Elias ) 대한피부과학회 2010 Annals of Dermatology Vol.22 No.3
In this review, I first provide relevant background information about normal epidermal barrier structure and function. I then update recent information about how inherited defects in either filaggrin and/or in the serine protease inhibitor, lymphoepithelial Kazal-type inhibitor 1, converge to stimulate the development of atopic dermatitis (AD). Next I explain the multiple mechanisms whereby a primary barrier abnormality in AD can lead to inflammation. Furthermore, I explore how certain acquired stressors, such as a reduced external humidity, high pH soaps/surfactants, psychological stress, as well as secondary Staphylococcus aureus infections initiate or further aggravate AD. Finally, and most importantly, I compare various therapeutic paradigms for AD, highlighting the risks and benefits of glucocorticoids and immunomodulators vs. corrective, lipid replacement therapy. (Ann Dermatol 22(3) 245∼254, 2010)
( Peter M Elias ) 한국피부장벽학회 2013 한국피부장벽학회지 Vol.15 No.2
Humans with darkly-pigmented skin (DS) (Fitzpatrick Type IV/V) display superior permeability barrier function and stratum corneum (SC) integrity/cohesion in comparison to humans with lightly-pigmented (Type I/II) skin (LS), independent of race, and barrier function is inferior in involved vs. uninvolved vitiligo skin. The reduced pH of the SC of DS skin (. ½ pH unit) could contribute to enhanced function, because reducing the pH of SC in LS individuals resets barrier function to DS levels. We evaluated here how pigmentation enhances epidermal barrier function in Skh1 (hairless albino) mice, which contain residual (non-melanized) melanocytes that lack pigment, and Skh2 (hairless pigmented) mice, where melanocytes generate abundant melanin restricted to the interfollicular epidermis. Barrier function was enhanced in Skh2 vs. Skh1 mice, which correlated with a more acidic pH that localized to the lower SC. The lower pH correlated further with persistence and extrusion of melanin granules into the extracellular spaces in the outer epidermis. Archived samples of DS human epidermis also showed melanin extrusion at and above the stratum granulosum (SG)-SC interface. Both acute barrier disruption and topical basic pH challenges accelerated melanin extrusion in Skh2, but not Skh1 mice, which correlated with a further decline in pH, enhanced activity of two acidic pH-dependent, ceramide-generating enzymes, b-glucocerebrosidase and acidic sphingomyelinase, and accelerated maturation of SC extracellular lamellar bilayers. Yet, pigmented melanocytes also could enhance barrier function by paracrine mechanisms, because Skh2 epidermis displays enhanced mRNA and/or protein levels for: a) epidermal differentiation proteins; b) lipid synthetic proteins; c) lipid transporters; and d) lipid-processing enzymes, changes that likely cannot be attributed to reduced acidity alone. Together, these studies demonstrate that superior barrier function in pigmented epidermis can be attributed to both pH-lowering juxtacrine and as-yet-undefined paracrine mechanisms.
( Shunpeng Song ),( Peter M Elias ),( Theodora M Mauro ),( Mao Qiang Man ) 한국피부장벽학회 2013 한국피부장벽학회지 Vol.15 No.2
Aged skin is featured by compromised epidermal permeability barrier homeostasis. Improvement of epidermal permeability barrier in aged skin is quite a challenge. Previous study demonstrated that topical hesperidin improves epidermal permeability barrier homeostasis in young mice. However, whether topical applications of hesperidin benefit epidermal permeability barrier function is not known yet. In the present study, we assessed the influence of topical applications of hesperidin on epidermal permeability barrier function and its underlying mechanisms in aged murine model. 12-15 month old hairless mice were topically treated with either 2% hesperidin or 70% ethanol alone twice daily for 25 days. At the end of study, stratum corneum function was assessed with an MPA5 physiology monitor. And barrier recovery rates were determined at 2 and 4 hours after barrier disruption by repeated tape-stripping. Our results show that topical applications of hesperidin lowered basal skin surface pH and increased basal transepidermal water loss. However, barrier recovery was significantly accelerated by hesperidin. The improved barrier function correlated with up-regulation of barrier-related protein, lipid synthetic enzyme and their mRNA expression. Moreover, topical hesperidin also significantly increased expression of epidermal mRNAs for mBD3, NHE1 and sPLA2g2f. These results suggest that topical application of hesperidin could be useful for preventing skin aging and treating aged skin.