Moisturizer may be harmful to people with defects in barrier
Recent work in the "sensitivity skin" animal model reveals the possible defects that most moisturizers on the market today. These moisturizers appear harmless when applied to normal skin showing a strong barrier, but these products can be toxic when applied to individuals with self-reported "sensitive" skin, or individuals with a history of AD.
In fact, these situations are rare because usually these "risk" people will be especially excluded in product testing. While sometimes these products can achieve short-term relief from the skin barrier, because they further damage the skin barrier, it triggers a vicious cycle that requires repeated use of these products. The barrier pathogenesis of
AD and the effect of moisturizer on AD
Atopic dermatitis (AD) Barrier pathogenesis
AD is associated with mutations in a variety of structural and enzyme proteins, which interfere with the loading or delivery of lipids and enzyme contents of plate bodies into the extracellular space (Figure 1).
In normal skin, the secreted lipids form a layered bilayer, filling the extracellular space, accounting for about 10% of the skin mass. The inability to provide complete lipid supplementation to SCs results in a decrease in the amount of extracellular lipids in AD, creating a leaking "brick and mortar" barrier that allows the skin to lose moisture unhindered (Figure 1). One direct consequence of the defective delivery mechanism of
is the decrease in the lipid content forming the outer layered bilayer, which is necessary for the permeability barrier. Furthermore, since both permeability and antibacterial barriers are closely related and interdependent functions, barrier defects not only lead to loss of body fluids, but also to unimpeded penetration of microbial pathogens and allergens. Further consequences of a defective barrier linking barrier defects to characteristic immunophenotypes.
Moisturizer does it work for AD's skin barrier repair?
As mentioned above, barrier abnormalities in AD are caused by mutations that disrupt the synthesis, loading, or secretion of the contents of the platelet (Figure 1). The effects of these abnormal mechanisms are the reduction of all three key barrier lipids, and further decreases in ceramide content and fatty acid chain length.
Moisturizers can relieve symptoms by replenishing moisture, but they have not been proven to provide treatment for AD. Whether they can prevent the initial development of AD, as some studies have shown, is also controversial.
