Atopic dermatitis (AD)

Atopic dermatitis (AD), more commonly known as Eczema, is a chronic inflammatory skin condition. It often begins in infancy in about 20% of children, and 10-20% of those will continue to suffer from AD into adulthood. The development of AD is multifactorial, involving genetic factors, environmental influences, and the immune system. Our microbiome, which refers to all of the microbes that live on and inside our bodies play a crucial role in our immune system. In skin diseases like AD, we see that there are changes in the composition of the microbiome, which can cause dysfunctional immune responses and can lead to their development.

The skin and the microbiome that resides on it plays a critical role in maintaining a physical barrier between the inside and outside world. In those with AD we see an altered skin microbiome, characterized by a decrease in diversity and over abundances of certain species. Essentially, altered ratios of the “good” and “bad” bacteria. Imbalances as such are known as dysbiosis. The consequences of the skin dysbiosis results in a breaking down of the skin barrier, which increases susceptibility to allergens, and promotes inflammation and immune responses. This results in the classic symptoms of AD such as dryness, redness, and itching.

We are seeing more and more in the research that the microbiome of our gastrointestinal tract impacts our skin microbiome – this is known as the gut-skin axis. Dysbiosis of the gut microbiome can lead to inflammation, and systemic immune dysfunction, which has been shown to alter the skin microbiome. 

When we are born our gastrointestinal tract is sterile, and bacteria and other microbes begin to colonize throughout the first few years of life, until the microbiome stabilizes around three years. This is a vulnerable period of time while the microbiome establishes itself as well as the immune system, which shapes an individuals risk of AD. These changes can continue into adulthood, and contribute to the chronicity of the condition. Research has shown that women who take probiotics during pregnancy and breastfeeding can alter the microbiome in infants and change their susceptibility to skin conditions such as AD. Probiotic supplementation of specific strains in infants have shown to develop milder forms of AD, through alteration of the gut microbiome and immune processes. 

The gut microbiome can be influenced by many environmental factors as well, such as stress, diet, and antibiotic use. Diets higher in sugar have shown to allow the “bad” microbes to flourish, while diets higher in fruits and vegetables promote growth of the “good” ones. Over-prescription of antibiotics, especially at a young age can dramatically reduce microbial diversity, and lead to dysbiosis. 

Promoting microbial diversity of the skin and gut from an early age appears to be crucial and therapies aimed at improving diversity continue to be explored to alter disease development and progression. As we continue to understand the intricate relationship between the microbiome and AD it opens up new avenues for prevention and care for the millions that are affected. 

Resources

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