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It's All About the Barrier
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Feb 9, 2009
Dear Friends,
A belated happy new year! I hope that 2009 will be a good year for everyone! I'm keeping my
fingers crossed that Austin will somehow escape the worst of the economic troubles we're
facing. Some of you know that macroeconomics is a hobby of mine, and I could go on for
awhile on this subject, but instead, I'll get down to business.
One of the most common questions I get from patients is, "What should I do with my skin?"
This always gives me pause. It's a perfectly reasonable thing to ask a dermatologist. But it
makes me think of a scenario in which one might ask an accountant at a party, "What should I do
with my taxes?" There is an answer, of course, but it's a little more complicated than just a few
quick pronouncements. I love to talk about skin, but to get it right for an individual person could
take some time. Everyone has different skin issues; some are dry, some are oily, some are
sensitive, some aren't. Then there's age, hormonal status, heredity, and environmental influences to consider. Skin of color has its own set of issues. On top of all this, medications, some of which are prescribed by us dermatologists, also influence the way our skin functions. So when I decided to write a newsletter about skin care, I must have been insane to think I could cover the whole topic in one page! What was I thinking?? Therefore, in order to preserve my sanity, and not bore you to tears, I will divide and conquer. I will attempt to write a series of letters covering the most important categories of skin care: moisturizing, photoaging, cosmeceuticals, sensitive skin, and skin of color. This may take all year!
First, let's look at what the skin does and the importance of barrier function. As you may know,
the skin is the largest organ in the body (dermatologists are proud of that fact and will tell anyone
who will listen). The skin has numerous functions: 1. it has a social and reproductive function;
i.e. it advertises our general health and youth to others; this is important in social and work
situations and in finding potential mates. 2. It mediates the sense of touch, one of the five
senses. 3. It maintains our body temperature, through the mechanisms of sweating and
vasodilation/vasoconstriction. 4. It pads our bones and muscles with a layer of subcutaneous fat, which functions as a shock absorber (and also contributes to temperature homeostasis). 5. It has its own immune system, which protects us from bacteria, viruses, and parasites. 6. It protects us from ultraviolet radiation. 7. Finally, (and perhaps the most important of all), it provides a barrier between us and the outside world. Obviously, without our skin, water would seep out of our bodies and we would quickly die. (By the way, one of the reasons I went into dermatology was that after a month's rotation at the Shrine Burn hospital, I realized just how important the skin is). So, an intact skin barrier is necessary for our survival. It keeps good stuff in (i.e. water) and bad stuff out. But on a more microscopic scale, skin barrier function is important to maintain the function and appearance of the skin itself.
What do I mean by that? Well, skin requires a certain level of moisture to do its job. The outer
layer of skin usually contains 20-35% water. The "skin barrier", also known as the stratum
corneum, is comprised of a dead flattened layer of cells called corneocytes, forming the "bricks",
and the intervening layer of lipids , forming "the mortar" This bricks and mortar structure
prevents water loss through the skin. The living epidermis residing just below the stratum
corneum is in a constant state of activity and is responsible for repairing the stratum corneum and making new lipids for the barrier. When our barrier is disrupted by trauma, changes in humidity, ultraviolet exposure, harsh cleansers, or any number of environmental insults, it sends "distress signals" to the epidermis to initiate the repair process. However, sometimes, the repair
mechanisms can get overwhelmed by disease states, such as psoriasis, eczema, severe dryness, etc. Now, the skin barrier is broken and the skin cannot function well. Without adequate hydration, the processes that normally cause dead skin cells to shed is disrupted and the skin becomes flaky, rough, dull, and inelastic, leading to cracks and fissures. The "distress signals", also known as cytokines, activate the inflammatory cascade, leading to further barrier disruption. Thus, skin disease leads to barrier dysfunction, but it also goes the other way: barrier dysfunction can lead to skin disease. This is why moisturizing is such an important part of treating skin diseases such as eczema and psoriasis. "It's half the battle" as I tend to say.
But there's more. We now know that inflammation is the final common pathway for multiple
illnesses, from arthritis to heart disease to certain cancers to autoimmune diseases, to aging itself.
With respect to the skin, we know that the inflammatory cytokines produced by distressed skin
lead to upregulation of a group of proteins called matrix metalloproteinases, which chew up
collagen and leave us with wrinkles. So, in order to prevent skin aging, we need to prevent skin
inflammation. How do we do that? By treating our skin well, protecting it from ultraviolet
radiation with sunscreens and sun avoidance, avoiding harsh cleansers, using topical antioxidants (more about this in future letters) and maintaining a healthy barrier with adequate moisturization. When I was a resident, it was considered a myth that moisturizers prevented wrinkles. Sure, they made the skin look smoother, but that was it. Well, it turns out that the "myth" might actually have some truth to it!
Should everyone moisturize? Probably, unless you're naturally oily, in which case you
obviously wouldn't need to. If you suffer from psoriasis, eczema, or seborrheic dermatitis (facial
dandruff), absolutely! Even acne sufferers can benefit from a lightweight moisturizer, as it has
been shown that improving barrier function improves acne. (Also, many acne treatments leave
the skin dry). Rosacea patients tend to have dry skin and an inherent barrier dysfunction, so
moisturizing is essential in this condition.
There probably aren't any bad moisturizers, but some may be better than others. Research in
skin physiology has shown that there are 3 main lipids in the skin barrier: ceramides,
cholesterol, and fatty acids. We are now starting to see the advent of new "physiologic"
moisturizers on the market that do more than just provide an occlusive water barrier; they
actually help the skin rebuild the lipid barrier. We frequently recommend the "CeraVe" products
to our patients with dry skin. This is a ceramide dominant moisturizer that is particularly
effective for eczema. Other recommendations include the Dove ProAge line (face and body) and
Vaseline Intensive Rescue Clinical Therapy (body). There are now several prescription
physiologic moisturizers, such as EpiCeram. Don't ask me why they are prescription only; I'm
sure it has to do with $$.
We just started carrying a facial cream called "Barrier Replenish Cream" which contains a
barrier repair complex consisting of the 3 lipids mentioned above. I have been using it and it is
awesome! I am also trying the eye cream and facial lotion made by the same company and like
those very much also. I will probably start stocking the eye cream and possibly the lotion soon.
So, for those of you who have asked about an eye cream, this may be the best I've found. I'll let
you know when we get it in.
Sorry for the commercial plug there; I really prefer these letters to be educational. But the cream
is $35.00 for 2 oz., if you're interested. :) OK, I'll stop now.
Have a great week and thanks for reading,
Kathy Farady
Balcones Dermatology
PS I'll be in South Beach, FL for a cosmetic meeting later this week. I hope to learn lots of
good stuff!
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Katherine Farady, M.D.
phone: 459-4869
David: ext 19
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