Uncover the primary causes of atopic eczema, its frequent trigger factors, and the risk factors associated with this common skin condition.
Summary
The causes of atopic eczema, also frequently referred to as atopic dermatitis, are multifaceted; genetics play a significant role by interacting with environmental factors.
Eczema, particularly atopic eczema, has a significant genetic and hereditary component. Several genes, including the filaggrin gene, are involved in its development.
Therefore, atopic dermatitis tends to affect children within the same family. Children whose parents suffer from eczema or other allergic diseases such as asthma and hay fever have a 50 to 70% risk¹ of developing atopic dermatitis. If both parents are affected, this risk increases to 80³.
Over the past 40 years, atopic dermatitis has become increasingly common in the general population, but genetic causes of eczema alone cannot explain the rapidity of this evolution.
This increase is due to changes in the environment:
Common mutations of the "FLG" gene lead to a deficiency in filaggrin, a protein essential for skin cell development, the integrity of the skin barrier, and skin hydration. Filaggrin breaks down into NMF, a key component of skin hydration. Besides the "FLG" gene, genes that maintain the epidermal barrier or immune response are associated with eczema. For example, mutations in genes coding for inflammatory molecules (cytokines) are involved in atopic dermatitis causes.
Atopic dermatitis is an inflammatory disease associated with abnormal activation of specific immune system cells. These cells promote the production of a type of antibody linked to allergic diseases. They also involve types of pro-allergy cytokines that reduce the expression of the filaggrin gene, even in people without a mutation of this gene.
These cytokines also reduce essential proteins for immune defenses, making the skin more vulnerable to infections, especially by the bacterium Staphylococcus aureus.
Thus, specific treatments for atopic dermatitis, such as monoclonal antibodies, are effective in severe eczemas by targeting cytokines activating the inflammatory response.
In individuals without eczema, the stratum corneum, the outermost protective layer of the skin, is composed of corneocytes, which are well-organized, flat, and sturdy cells. Natural moisturizing factors (NMF) in these corneocytes retain water, maintaining skin hydration.
However, filaggrin gene mutations associated with atopic eczema lead to:
Stress is an aggravating factor for atopic dermatitis as it disrupts the immune system and the skin barrier.
Stress directs the immune system towards an allergic-type response, known as Th2, thus increasing the proportion of cells (eosinophils, mast cells) and antibodies (immunoglobulins IgE) associated with allergy in atopic dermatitis. Mast cells release pro-inflammatory compounds like histamine, creating the itching associated with eczema.
Stress disrupts skin health; it affects the epidermis's ability to regenerate correctly, promoting the shedding of corneocytes and thus disrupting the cohesion of the stratum corneum, the protective layer of the skin. It, therefore, increases the permeability of the skin barrier.
Environmental trigger factors for atopic dermatitis vary from person to person; a particular allergen may trigger eczema symptoms in one person but not another.
Environmental allergens, including dust mites, pollens, pet dander, and some molds, can trigger eczema in predisposed individuals. Similarly, exposure to pollution, urban or industrial, as well as tobacco smoke, can trigger eczema flare-ups.
Common irritants, such as soaps, detergents, solvents, and even cosmetics, can aggravate eczema or trigger a flare-up.
The climate can impact eczema. Cold and dry weather can dry the skin, while heat and humidity can increase sweating and irritation, aggravating atopic dermatitis. During seasonal changes, some people experience a worsening of eczema symptoms.
Baths or showers that are too hot or too frequent and harsh cleaning products can make the skin dry, especially on the face and hands, and trigger a flare-up.
In some atopic individuals, particularly children and infants, consuming foods to which they are allergic can trigger an eczema flare-up or worsen existing symptoms. The most common food allergens include eggs, milk, peanuts, soy, wheat, seafood, and nuts (walnuts, almonds, etc.).
Moreover, various foods can aggravate eczema without triggering an allergic reaction; acidic foods like tomatoes, pineapple, or citrus fruits, spices, and preservatives can cause skin inflammation and exacerbate eczema symptoms.
Identifying the trigger factors of atopic dermatitis is fundamental.
Common environmental allergens include dust mites, pollens, pet dander, and some foods.
Common skin irritants include strong soaps, detergents, harsh cleaning products, and synthetic fabrics or wool. They can cause mechanical or chemical irritation to already sensitive skin. It is recommended to opt for gentle, hypoallergenic products and prefer clothes made from natural fabrics, like cotton, which are less likely to irritate the skin.
Moreover, climatic variations, such as extreme cold or heat, can also exacerbate eczema symptoms by affecting skin hydration.
Finally, fine particles in polluted air can penetrate the weakened skin barrier and trigger or exacerbate inflammatory reactions. Similarly, tobacco smoke, whether through direct or passive exposure, can irritate the skin and contribute to the frequency and severity of eczema flare-ups. Therefore, avoiding polluted environments and abstaining from or limiting exposure to tobacco smoke is advisable to help keep the skin in the best possible condition.
Regularly using emollients is central to maintaining skin hydration and restoring its barrier function. These products help trap moisture, reduce dryness and itching, and prevent eczema flare-ups. Applying emollients after bathing or showering when the skin is still slightly damp is recommended to maximize their effectiveness.
Proper skin care based on daily skin hydration with an emollient is essential for eczema. Doctors also recommend avoiding soaps in favor of gentle, fragrance-free products, such as DEXERYL washing oils and creams, taking short, lukewarm showers, and patting the skin dry rather than rubbing. Additionally, wearing clothes made of cotton or linen rather than synthetic fibers or wool can reduce skin irritation.
Relaxation techniques such as meditation, yoga, or breathing exercises can help reduce stress, a psychological symptom and trigger for eczema.
Doctors recommend not changing the diet unless a food allergen is identified. An allergist can assist in identifying and eliminating food allergens causing eczema.
Atopic dermatitis is not contagious. Eczema or atopic dermatitis is the result of immunological dysfunction and damage to the skin barrier. There is a hereditary component. Between 50% and 70% of people with atopic dermatitis have a parent in the first degree who is also affected. This risk rises to 80% when both parents are affected. Other common triggers such as stress, irritating products and clothing, and changes in temperature can also explain the onset of atopic dermatitis.
Triggers can vary, but often include genetic factors, allergic reactions, environmental irritants and climate change. It is advisable to: avoid baths that are too hot and too long, and opt for soft cotton clothing that does not rub or irritate the skin.
It has not been proven that certain foods can aggravate Atopic Dermatitis. If in doubt, talk to your doctor, who may prescribe a check-up by an allergist if necessary.
To manage atopic dermatitis, it is important to identify and minimise potential triggers. These can include household allergens such as dust mites, skin irritants such as cleaning products, household products or perfume, the washing products used and climate change. Avoid harsh washing products and use emollient creams to protect your skin.
References
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