Atopic dermatitis is a morbidity that definitely needs more attention. In the last year, new associations between AD and illnesses like depression and autism spectrum disorder were discovered. Why is it called atopic? Because it cannot be completely described in its clinical features by a common cause. Generally, it is associated with an overreaction to allergens or exogenous irritants mainly due to genetic factors. [1]
AD can significantly affect the quality of life of infants and adults, due to itchiness and skin irritation driven by eczematous lesions and desquamation. Children can develop sleep issues leading them to stress and attention deficit disorders that can affect their social life and school learning. [1]
Due to immunological mechanisms, skin appears very dry and does not perform its correct protecting function, which is the reason why AD patients can easily develop infections. Basically, skin normally acts as a barrier from the external environment, aggressive pathogens, and UV radiations as well as contaminants. The most exposed layer of the skin is the stratum corneum (SC) which can be seen as a brick wall. The corneocytes, the cells present in the epidermis, form the bricks, while the lipids and the water are the mortar. Proteins (keratin, filaggrin, collagen) help with the formation and development of the corneocytes that stratify and assemble properly in the SC. [2]
That’s why skin is a semi-permeable barrier that allows the passage of certain molecules! In atopic dermatitis, this structure is defeated, and the ratio of lipids is unbalanced. This is true for many more skin disorders like acne and psoriasis and some age or environment-related skin dryness and redness. The skin lipids are called ceramides and are the main constituent (fun fact: they consist of 8 different types and derive from sphingolipids) of the stratum corneum together with cholesterol and free fatty acids. Let me show you what they look like:
Figure 1: Ceramide-1 phosphate
Cer1 and Cer3 levels are reduced in AD; studies related this lack to the dry and flaky skin appearance and the incorrect build-up of the other ceramides. For this reason, most of the moisturizing creams suggested by dermatologists and pediatricians must contain the right ratio of ceramides to restore the balance of defected skin. It can happen that applying creams with the wrong content of ceramides can even exacerbate the disorder, so generally, cosmetic formulations contain ceramides, cholesterol, and free fatty acids 3:1:1.
But before deepening the cosmetic options, let’s revise together what’s a moisturizer. [3]
Figure 2: types of moisturizing agents
Occlusive moisturizers don’t address the pathogenic morbidities recognized in the progression of AD, while some emollient creams containing sunflower, safflower, borage, and corn oil, rich in essential fatty acids like d-linoleic acid, can reduce the inflammation and act as nutrients. Botanical ingredients have become very popular, like apigenin present in chamomile which can improve AD symptoms. Also, some creams are enriched in prebiotics that address the cutaneous microbiota of the skin, helping to restore the good commensal microorganisms that act as a defense against aggressive pathogens such as Staphylococcus Aureus.
Currently, the most used medical skincare applications name ceramides as the first ingredients for moisturizers formulations for AD or other skin disorders. These creams have a pH < 5 to contrast the high pH of inflamed skin and contain skin-identical or synthetic ceramides that are absorbed in deeper skin layers at the level of cells. They stimulate the synthesis of new lipids that are delivered into the extracellular spaces, promoting barrier restoration, and reducing TEWL. So, compared to petrolatum they also have an anti-inflammatory action because they dampen the immune response present during the disease.
In conclusion, for prevention, recent studies found benefits in treating infants with this kind of emollients, as well as adult patients with mild to moderate AD with these creams to alleviate the symptoms, reduce the risks of relapses, and diminish the topical use of corticosteroids and related skin dystrophies. Ceramides, according to guidelines, can ameliorate the immunological and physiological symptoms of the disorder and must always be present at every treatment stage. [3,4]
If you are dealing with AD or want to find out more about this topic click here: https://www.jaad.org/article/S0190-9622(13)01095-5/fulltext (section 1)
If you want to deepen even more, here's a super updated paper on associated comorbidities and AD:
Davis DMR et al. AAD Guidelines: awareness of comorbidities associated with atopic dermatitis in adults. J Am Acad Dermatol. 2022 Jan 24; S0190-9622(22)00080-9. DOI: 10.1016/j.jaad.2022.01.009
References
1. Nutten S. (2015). Atopic dermatitis: global epidemiology and risk factors. Annals of nutrition & metabolism, 66 Suppl 1, 8–16.
2. de Lucas, R., García-Millán, C., Pérez-Davó, A., Moreno, E., & Redondo, P. (2019). New Cosmetic Formulation for the Treatment of Mild to Moderate Infantile Atopic Dermatitis. Children (Basel, Switzerland), 6(2), 17. https://pubmed.ncbi.nlm.nih.gov/30700045/
3. Coderch, L., López, O., de la Maza, A. et al. (2003) Ceramides and Skin Function. Am J Clin Dermatol 4, 107–129. https://pubmed.ncbi.nlm.nih.gov/12553851/
4. Elena Galli, Nunzia Maiello, Giampaolo Ricci, Elisa Anastasio, Giuseppe Baviera, Lucia Caminiti, Elena Carboni, Rossella Carello, Francesca Cipriani, Iria Neri (2018), Il perché dello “skincare” nella dermatite atopica, Rivista di Immunologia e Allergologia Pediatrica, 22-30, Fascicolo 3.
Credits:
cover photo: pexels.com
figure 2 was made on canva.com