By Dr. Peter Lio
The most recent issue of the Journal of Allergy and Clinical Immunology (JACI) featured on its cover “Atopic Dermatitis: Peeling Away the Layers” emblazoned across a magnified photograph of peeling skin. Among the articles within were several that should be intensely interesting to anyone with a family history of allergic disease, particularly those with very young children and those who are planning to have more. We turned to Dr. Peter Lio of Chicago who has contributed to this website in the past to answer questions raised by these articles.
AAC.com: Two of these articles studied the protective effects of emollients, moisturizers, on infants who have a “first-degree relative” (parent or sibling) with a history of Atopic Dermatitis (AD). Can you explain what these medications do and why these particular children are at risk?
Dr. Lio: In the past several years, the underlying story of the cause of eczema has been rapidly developing. Historically, the “root cause” for eczema has been explained by everything from evil spirits, imbalanced humors, and neurotic/psychological causes to toxins and pollutants. For the past several decades, the predominant theory has really centered around the immune system as being the primary culprit, with the poor skin stuck in its warpath. However, as we are learning more about certain gene mutations that fundamentally disrupt the skin barrier, we can see that perhaps the skin was not so innocent after all! Indeed, for some patients at least, this “leaky skin” may well be the fundamental issue, with all of the associated problems (immune issues, infections, allergies, asthma, etc.) arising from this. If this is the case (and it actually does seem to be the case for some–a larger question remains about the other patients where this does not seem to be a primary issue), then it follows that by supporting the skin with a simple moisturizer, one can actually prevent the development of all the other problems. It’s incredibly exciting because it really would be a safe, totally drug-free, non-immune-suppressing solution to a terrible disease. By picking patients who are at high risk of developing eczema and allergies (i.e., having a first-degree relative with AD), the researchers are able to show that the number of patients who actually develop eczema is much lower than would be expected without treatment.
AAC.com: AD is evidence of a deficient barrier. The skin is the largest organ in the body and a primary defense against infection and allergens. Can you tell us the characteristics of a healthy barrier?
Dr. Lio: The skin does a number of things for us, but one of its most important tasks is to act as a barrier: to keep water in, and keep bacteria, allergens, and irritants OUT. A healthy barrier does this naturally and without drama. A testament to how powerful our skin barrier is can be seen every day when people use harsh cleansers to scrub countertops or do dishes: these are often very irritating chemicals, but most people can use them without gloves as the barrier is strong and healthy. Healthy skin is generally soft and supple, in part due to the water held in place by natural moisturizing factor. When the barrier is damaged, not only does the skin often feel rough and dry, but can actually become cracked and fissured, and in severe cases, be totally open and oozing, much like a burn. In such cases, the barrier is damaged and the entire body is–in a manner of speaking–in peril since that part of the barrier is down.
AAC.com: In an earlier article for this website, you described a number of interventions being investigated that were complicated and expensive. The use of an emollient looks too easy. Why is it that in 2014 it becomes a cover story in a distinguished journal?
Dr. Lio: This is a provocative question! The good news is that I’d like to think we’ve been recommending aggressive moisturizing from the earliest beginnings of modern medicine. We recently did a review of several different guidelines for managing AD and, unanimously, all stressed the importance of moisturizing as an absolutely key part of treating eczema. I think there are two reasons it’s exciting: first, we now are actually understanding why it works, rather than simply knowing it does from experience, and that is always a powerful helper when trying to get patients to follow a plan. It turns out that when studied, many patients are not great about sticking with moisturizing several times per day, even though we know that it does help. Sometimes, having a reason why it works can really make this chore more manageable. Second, there has been such a different focus on the “why” of AD for the past few decades, that this represents a real return to dermatology: the skin itself! So many people have suggested it is environmental toxins, all food-related, or purely an immune problem, that the focus on the skin has been lost. I want to stress that this does not mean that those other things do not play an important role for some or even all patients: clearly, other things are behind this epidemic than simply a gene mutation, because we know eczema has increased tremendously, and it is very unlikely that the genes have changed this much in just a few generations. It is with excitement that we learn new things, but this is a complicated and very humbling disease. Anyone who claims a simple answer for it all is almost certainly deluded; this is almost certainly more than just one disease, so even if there is an “easy” answer for one subtype, it would likely not apply to the others. An analogy to this might be to imagine a number of houses near a river. Most houses are well sealed and never get water in the basement. A few houses get water in the basement frequently and have damaged carpets, furniture, and perhaps now even have mold growing in the house–it’s a disaster! It seems so obvious that the answer is to figure out why the water is getting in and to stop it. Maybe for some houses, there are cracks in the foundation; for others, the drainage system is broken. It would be folly to yell at the water or blame the river, but, in a way, that is exactly what has been happening for several decades.
AAC.com: We featured an article about a pediatric allergist not long ago who said that while dermatologists and allergists work together towards the same goals, they do have some differences. For example, allergists seem to recommend more frequent bathing than dermatologists. Are there any other areas where you see such differences?
Dr. Lio: Another provocative question! I think that it is very difficult to generalize about these things since there is so much variability between each individual doctor. I do think that allergists are trained to focus on triggers and allergies, while dermatologists generally do not have as much emphasis on these during training. I also think that we probably actually get different subpopulations of patients with eczema; those with more allergies tend to see allergists, perhaps, while those with more “pure” skin disease probably are more prominently represented at the dermatology office. We recently wrote a fun piece comparing the Allergy guidelines for AD treatment with those from Dermatology; there are some differences as you suggest, but largely, I am happy to report that they are very similar. Interested readers can find a version of that paper here.
AAC.com: It would seem that use of an emollient is a pretty harmless intervention that parents could undertake even if their child’s pediatrician doesn’t raise the issue about a family history of AD. Are there any precautions they should take about which ones to use?
Dr. Lio: Agreed, which is part of why we are so excited about this. I think we generally want a cream or ointment rather than a lotion, and we don’t want any fragrances. Ideally, something without preservatives and with minimal other “stuff” would be ideal. I’m a big fan of sunflower seed oil, and that has been shown in a number of studies to be really helpful for skin barrier in babies; moisturizers that have this in them are particularly desirable.
AAC.com: Finally, still another article is entitled “Peanut allergy: Effect of environmental peanut exposure in children with filaggrin loss-of-function mutations.” This article is surely going to induce some hand-wringing among parents who have occasionally eaten peanuts on a couch or used an emollient with peanut oil. Could you explain these mutations to our readers? Could you tell us who gets them? Should infants be tested for these mutations or should those at risk, say first-degree relatives, just take the precautions described above?
Dr. Lio: This is tough and important, and I am also the father of a daughter with severe peanut and tree-nut allergy. The truth is that it probably has less to do with the actual household than this study suggests; there are a lot of allergens in the world, and just entering a candy shop or grocery store probably bombards the skin with all sorts of allergens in the air. Moreover, there is a very strange and somewhat contradictory set of studies that suggest early oral introduction of certain allergens may actually be protective of developing allergies. The fact that there is a peanut-based Israeli snack called Bamba that is popular with kids there and the fact that peanut allergy is very low in Israel is often cited as an example of this effect; clearly, those households that are feeding the allergen to the children will also have higher environmental levels of the allergen, so this is probably not quite as simple as it may seem. Importantly, there has also been discussion that in those who have low-level allergies to an allergen, if they go to very strict avoidance, there may actually be a higher chance of actually becoming more allergic when re-exposed in the future. This suggests that perhaps a low-level in the environment might also be somehow protective of developing the most severe allergies (anaphylaxis). For now, I think that most of this needs to be taken as the beginning of understanding a really complicated disease, and not yet at the level to make too many hard-and-fast recommendations. Science is a slow, self-correcting process of testing ideas, refining, and often replacing them. It’s ugly but it does work, even if it seems very slow at times. So, I’d say no hand-wringing yet. Besides, hand-wringing is no good for the skin barrier, and we don’t want to damage that, right?
Peter A. Lio, MD is an Assistant Professor of Clinical Dermatology & Pediatrics at the Northwestern University Feinberg School of Medicine, and a Diplomate of the American Board of Dermatology. Dr. Lio received his medical degree from Harvard Medical School, completed his internship at Boston Children’s Hospital and his dermatology training at Harvard. He served as a full-time faculty at Harvard (Beth Israel & Children’s Hospital Boston) from 2005-2008 before returning home to his native Chicago to join Northwestern and Children’s Memorial Hospital. He is also a trained acupuncturist and a leader in the Chicago integrative health care community. For more of Dr. Lio’s writing on related subjects, click here. Illustration by dermatologyupdate.com.au