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 the Journal of Human Evolution, we provided many reasons why this hypothesis is flawed and suggested instead that pigment dilution developed as a form of ‘metabolic conservation’. While abundant pigment was needed to protect our skin from the intense ultraviolet light of equatorial Africa, it was no longer needed in the weaker light of the higher latitudes. Hence, mutations arising in the genes for pigment-producing proteins that reduced pigmentation were retained, because they allowed skin to divert energy towards other, more urgent requirements. [Read more…]

What Allows Our Skin Cells to Shed?

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Layers of the Epidermis. Illustration by Jessica C. Kraft

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 scales, such as what commonly occurs as previously sunburned skin peels away or… [Read more…]

Thoughts on the Rational Treatment of Atopic Dermatitis

This is the 4th in our series of updates on atopic dermatitis. In the preceding articles we considered why so many more children nowadays are developing eczema, what we know about the genetic underpinings of the disease, and how defects in the skin barrier and loss of the acidic pH on the skin surface are key to understanding how the dermatitis develops. In this post we consider how this information provides the basis for new, rational paradigms for treatment.


Migration back to life on the farm is probably not an option for many, but there are steps that people with atopic dermatitis can take to address their skin’s vulnerability.  For a start, they can practice ‘gentle skin care’ and avoid extracting the natural oils from their skin that are essential for its barrier function by modifying their bathing routines. [Read more…]

Atopic Dermatitis: Is It All About pH?

lemons crop

In two earlier posts we discussed why atopic dermatitis is becoming more prevalent and what is known about the genetic underpinings of this common disorder. In this installment, we look at how the most common gene associated with atopic dermatitis acts to produce the skin condition.

It has known for decades that the skin has a “sour surface”. The pH of the skin surface is acidic (~5), while our cells and blood have a nearly neutral (~7.4) pH. This low surface pH is assumed to be critical to discourage the growth of bacteria and other microorganisms. Indeed, the microbes that normally inhabit our skin (our so-called ‘normal skin flora’) thrive in an acidic environment, while the pathogens that cause serious infections,  such as Staphylococcus aureus and the streptococci, do not. [Read more…]

Featured in Allure May 2013 Issue

Allure-Kindle-Cover-May-2013Our work on antihistamines and the skin also featured in the May 2013 issue of Allure magazine.  This work demonstrates that these commonly used drugs are applied directly to the skin they can improve the function of the skin barrier and also have potent anti-inflammatory effects.  This work holds promise for the development of new treatments for common skin disorders like atopic dermatitis and psoriasis.

Our Research on Antihistimines and the Skin Barrier Featured on Allure.com

A new treatment for common skin diseases like psoriasis and eczema (or atopic dermatitis), or other skin conditions with a defective skin barrier, is the hope raised by recent work from the Elias laboratory and featured in Allure this month.  These studies demonstrate that when antihistamines are applied topically to the skin, they improve the skin barrier.  This suggests that creams or ointments containing anithistamines of the type that do not cause sedation as a side effect could provide a safe and effective way to treat inflammatory skin disorders caused in part by a defective skin barrier, like eczema and psoriasis.