Contact eczema, or contact dermatitis, is a common skin inflammation. This skin disease is due to repeated exposure to a particular substance of domestic or professional origin. Recent discoveries have shed light on the role of the microbiota in contact eczema. Discover the origin and evolution of this dermatitis and how to avoid recurrences of contact eczema.
Eczema plays an important role in dermatoses , i.e. in skin diseases. 15 to 30% of children and up to 10% of adults are affected. In just 30 years, 2 to 3 times more people have developed this characteristic skin inflammation!
However, this term is very generic since it includes many pathologies :atopic eczema (or atopic dermatitis), varicose eczema, nummular eczema, bullous eczema, contact eczema… It designates the clinical translation of multiple causes.
The inflammatory plaques eczema are characterized by redness topped with small blisters that eventually rupture and ooze. There are also scales (small strips of skin that come off) and crusts. The patches of eczema are itchy and the affected person scratches. This behavior can lead to scratching lesions that are susceptible to infection.
Contact eczema (or contact dermatitis) is triggered by exposure of the skin to an allergen particular (clothing, cosmetics, medicine, etc.). Contact dermatitis can appear in both children and adults. Some types of eczema develop more in people with an allergic background (suffering from allergic rhinitis, asthma, food allergies, etc.). This is not the case for contact eczema.
The stages of contact eczema :
Several phases characterize the appearance and then the development of contact eczema:
The awareness phase:
Initially, the person is subjected to the presence of the offending allergen without developing symptoms. It is said to be sensitized by skin exposures. The allergen penetrates the skin whose barrier has been altered (by irritation for example), and activates the immune system responsible for defending us against external attacks. Despite the absence of symptoms, specific immune cells (lymphocytes) retain the characteristics of the allergen in memory .
The revelation phase:
During a new contact with the allergen, the immune system recognizes it thanks to the lymphocytes which have been stimulated by the allergen and have kept it in memory. An inflammatory mechanism defense is implemented and causes the symptoms of eczema within 24 to 48 hours. These symptoms first appear at the point of contact with the allergen before spreading over exposure throughout the body.
The remission phase:
Contact eczema disappears within a maximum of 15 days after exposure to the allergen if it has disappeared. However, if the exposure is permanent, the person may suffer from chronic contact dermatitis marked by skin thickening.
The triggering factors contact eczema are multiple and vary from person to person. Exposure to the allergen can be of occupational or domestic origin.
Occupational origins of contact eczema
Professions particularly at risk are those requiring manipulation:
Humidity and stress are also factors favoring contact eczema.
Domestic origins of contact eczema
Among the domestic substances incriminated, we find allergens of origin:
Certain substances, called photo-allergens , trigger eczema only after sun exposure. The molecules of the offending substance are transformed by the energy of ultra-violet rays (UV) from the sun, and then become allergenic. Eczema begins and will be more marked on areas of skin exposed to light.
Recent research studies have uncovered the role of the microbiota in several forms of eczema, including contact eczema.
The gut microbiota brings together all the microorganisms that live in our intestines.
Studies in mice show that the intestinal microbiota, modified by a genetic deficiency, may play a role in contact dermatitis . The researchers transferred the intestinal microbiota of mice affected by a form of contact eczema very similar to ours to mice that did not develop this skin disease. The discovery is amazing:they in turn developed the same contact dermatitis.
This phenomenon could be explained by a migration of bacteria from the intestine to the organs of immunity. They would then be able to modulate the responses of our immune system , and therefore our defense capabilities!
The set of microorganisms that live on our skin is called “cutaneous microbiota .
The relationship between skin microbiota and contact eczema is not yet clearly elucidated.
However research studies show cutaneous dysbiosis , i.e. an imbalance of the skin microbiota in several forms of eczema (such as atopic eczema for example). The return to balance of the skin flora seems essential for eczema to regress. A balanced microbiota notably maintains the physiological pH of the skin, i.e. an appropriate acidity, and fights against inappropriate inflammatory reactions.
In addition, subjects with atopic dermatitis (or atopic eczema) have a higher risk of developing contact eczema. The skin, already weakened by atopic dermatitis, allows allergens to penetrate more easily, which leads to contact sensitization. The role of the skin microbiota in atopic dermatitis, meanwhile, has been demonstrated more precisely.
Once sensitized to an allergen, the most effective prevention to avoid recurrences of contact eczema lies in the eviction of the allergen incriminated. Unfortunately, it is sometimes impossible to permanently avoid certain substances that are very present in everyday life, at home and at work.
If it is not possible to avoid the allergen, you can protect yourself with:
To fight against the penetration of allergens into the skin, you can adopt good habits to strengthen your skin barrier and promote the balance of the microbiota:
In order to promote the balance of the skin microbiota, certain cleansing products contain probiotics , that is, good bacteria for the skin. Others contain prebiotics which are sugars that feed the good bacteria of the skin microbiota.
