Atopic dermatitis (AD) is one of the most common chronic diseases in childhood. It usually affects 20% of children.
In recent years, much research is being done on the role that the gut microbiota may play in the onset and progression of AD, with the aim of improving the control of the disease.
The impact of environmental changes on the gut microbiota
It is well known that the microorganisms that inhabit the gut are key in immune development and regulation. Some research has found an imbalance in the composition of the gut microbiota that could be implicated in the onset of allergic diseases in genetically predisposed individuals.
Environmental and dietary changes in industrialized countries have improved many aspects of life, but they have an impact on the balance of the gut microbiota.
Dutch researchers found that the transmission of microorganisms from mother to child is influenced by maternal nutrition, the intake of broad-spectrum antibiotics and her health status. It can also be affected by cesarean birth, use of artificial breastfeeding and reduced skin-to-skin contact. Also, birth order had a great impact on the composition of the microbiota, so that the greater the number of older siblings, the higher the colonization rates of lactobacilli and bacteroides, while the rate of clostridia decreased.
The profile of the intestinal microbiota was studied in school-aged children living in a Metropolitan Region of Brazil. They included children with AD and controls. They found a higher presence of clostridium difficile, bifidobacterium spp and a decrease of lactobacillus spp in school-aged children with AD. In addition, children with AD had lower total eubacterial counts.
The skin-gut relationship
Some researchers speak of the skin-gut axis, referring to the mutual influence of changes in the composition and function of the microbiota in both the gut and the skin. This may be related to variations in immunity leading to inflammatory skin diseases such as atopic dermatitis. Some studies showed that participants who developed AD had a less diverse gut microbiome than healthy individuals. Some research pointed to a positive effect of probiotics on the severity of AD, although other studies have not confirmed this effect.
Currently, multiple research projects are underway that will allow us to better understand the healthy intestinal microbiota and its alterations in AD. Much remains to be known about the mechanisms that affect the immune system, but little by little these advances can be incorporated to improve patient treatment. The current evidence on the usefulness of probiotics to prevent or treat AD is small, although promising results are expected in the coming years.