Research from the Elias Lab

For nearly forty years, this University of California San Francisco-based research laboratory has focused on elucidating the structural and metabolic basis for the barrier function of the skin, including work aimed at understanding the cause and treatment of skin diseases.

How is pigmented skin more acidic?

 How is Pigmented Skin More Acidic?   As we discussed in an earlier post, darkly pigmented skin is superior to lightly pigmented skin. It functions better in holding in body water. It does a better job of preventing skin infections. And it is better at resisting mechanical trauma.  We then discussed work from the Elias laboratory demonstrating that this superiority is due to the lower pH of the skin surface.  In other words, darkly pigmented skin is more acidic. Yet darkly pigmented … [Read more...]

Our Sour Skin Surface

Did you know that the surface of our skin is acidic? That we have a sour skin surface, like vinegar or lemon juice?  Scientists have long known that we are covered by an acid mantle. But how the epidermis - the outer layers of skin - achieves this feat, conferring a pH of 5.0 or less to our skin surface, when the cells of our body and the blood and fluids bathing those cells have a more neutral pH of ~7.4, has until recently been something of a mystery.   To our surprise, as we were … [Read more...]

Highlights from the 2013 IID. Part 7: Is Acne a Disorder of the Skin Barrier?

It has been known for decades that the formation of keratinous plugs in the outlet of the sebaceous follicles is the first step in the process of acne vulgaris.  These 'comedones', (called 'open comedones' (blackheads) if the opening of the pore is wide and the plug is visible; and 'closed comedones' (whiteheads) if it is tiny and the plug buried under the surface), precede the development of inflammatory lesions (what we call pimples). It has also been known for a long time that individuals who … [Read more...]

Highlights of the 2013 IID. Part 6: Does barrier repair therapy improve skin defense against infection?

Prior work from our group has shown that the permeability and antimicrobial barriers in normal skin share many common features, and are co-regulated, such that perturbations in one function inevitably impact the other. We also showed that a variety of conditions that compromise the permeability barrier, including neonatal and aging skin, are also accompanied by a reduction in the production of the cathelicidin antimicrobial peptide, LL-37, a key defender against S. Aureus and Streptococcal … [Read more...]

HIghlights of the IID 2013. Part 4: The Good Side of Psychological Stress

It is widely held that the stress of our modern lives is bad for our health. And it is certainly true that stress (or, more precisely, 'psychological stress') can be harmful to the function of our skin. It delays wound healing. It can reduce our immune defenses against infection.  And, as we demonstrated several years ago, it can compromise the skin’s permeability barrier. It is also accepted by many that stress exacerbates chronic inflammatory diseases, like rheumatic disorders and inflammatory … [Read more...]

HIghlights of the IID. Part 3: How Melanin Is Good For The Skin Barrier

In previous work, we demonstrated that the skin of darkly-pigmented people possesses a tighter, more competent barrier to water leakage than does the skin of lightly-pigmented individuals.  Although we could attribute this to the much more acidic (lower pH) skin surface in individuals with dark pigmentation, just how either melanin or its parent cell, the melanocyte, confers these benefits was unknown. For the studies reported here, we took advantage of two closely related strains of hairless … [Read more...]

Highlights from the 2013 International Investigative Dermatology (IID) Meeting in Edinburgh: Introduction

Every 4 years, the Eurorpean, North American and Japanese dermatologic research societies host a joint meeting. Last week the 2013 International Investigative Dermatology meeting took place in Edinburgh, Scotland. Over the next several days we will summarize some of the highlights of research on the skin barrier that was presented there, alternating posts of research from the Elias group with work coming from other laboratories around the world. … [Read more...]

Highlights of the IID 2013. Part 1: Evolution and filaggrin mutations vs. vitamin D production

Did latitude-dependent differences in prevalence of filaggrin mutations evolve to support cutaneous vitamin D production? JP Thyssen and PM Elias. Skin became more lightly pigmented when modern humans migrated northward out of Africa into Europe and Asia. Evolutionary biologists increasingly accept the hypothesis that pigmentation lightened in order to allow more ultraviolet light to enter the skin, where it can then stimulate the formation of additional vitamin D. In a recent article in … [Read more...]

What Allows Our Skin Cells to Shed?

The epidermis is a self-renewing system. Old cells (or ‘squames’) are shed from the skin surface as new cells (‘keratinocytes’) are produced in the underlying epidermis and pushed outward into the stratum corneum to become 'corneocytes'. In normal skin, the process of desquamation is invisible and imperceptible.  But in some skin diseases, the production of cells may increase and/or the mechanism of shedding may be faulty, resulting in the visible build-up and eventual shedding of unsightly … [Read more...]

Why Early Humans Needed Dark Skin

The skin under the dark fur of most mammals  is pale or non-pigmented. Polar bears are an interesting exception to this rule – they have reversed the dark hair/light skin paradigm: their white hairs provide camouflage against the snow and ice, while their pigmented skin can absorb what little warmth the Arctic sun provides.  Ancestors of modern human, like other primates, also had pale skin under their dense coats of pigmented hair.  … [Read more...]

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