Childhood Eczema and Germs in the Gut

-From 2016, articles commented in the Journal and Focus will be posted here (selection by Prof. JH Saurat M.D.)

Childhood Eczema and Germs in the Gut

Postby CFH » Thu Oct 27, 2016 6:08 pm

Neonatal gut microbiota associates with childhood multisensitized atopy and T cell differentiation.
Fujimura KE, Sitarik AR, Havstad S, Lin DL, Levan S, Fadrosh D, Panzer AR, LaMere B, Rackaityte E, Lukacs NW, Wegienka G, Boushey HA, Ownby DR, Zoratti EM, Levin AM, Johnson CC, Lynch SV.
Nat Med. 2016 Oct;22(10):1187-1191. doi: 10.1038/nm.4176.

Why read this article ?
-The following article published in Nature shows how organisms living in the gut (Microbiome) can influence skin properties such as in atopic dermatitis (AD).

What do changes in the Microbiome contained the Gut do to the Body ?

Effects concern many systems and here are some of them:
-In the lung microbiota influence gene expression which play a role in allergic asthma
-In the adipose tissue, microbial metabolites can have an influence on Obesity and Insulin resistance.
-In the pancreas, insulin secretion can be impaired and lead to type 2 diabetes.
-In the Brain, stress response can be influenced as there is an effect on serotonin metabolism

This article goes one step further by highlighting the known influences on the skin, more precisely on Atopic Dermatitis (AD).

How was the influence of the Microbiome on AD evaluated ? What did it show ?
-3 Neonatal Gut Microbiomes were determined (NGM) and relative risks to develop AD were calculated in each of them. The group with the highest risk of developing AD (NGM3) showed the following:

"lower relative abundance of certain bacteria (for example, Bifidobacterium, Akkermansia and Faecalibacterium), higher relative abundance of particular fungi (Candida and Rhodotorula) and a distinct fecal metabolome enriched for pro-inflammatory metabolites."

-NGM3 showed and increased proportion of T lymphocytes of the CD4+ type - These produce *Interleukin 4 (Il-4). (fecal water culture)

Conclusion: CD4+ T cell dysregulation is a characteristic of AD which could be the result of Microbiome changes.

Comment: Stool analysis is a straightforward process and the revelation of a distinct Microbiome at birth might be helpful in determining the future risk of developing AD. This has preventive and therapeutical implications.

Germs in the Gut, a short introduction
-Trillions of bacteria produce metabolites that in turn sense signals to the rest of the body thus altering immune and hormonal systems.

-Bacteria are of several species and the specific composition is influenced by genetic and hormonal factors. There is a tendency for each individual to have a specific composition called an enterotype. There are theoreticaly 3 enterotypes, not a lot but it makes sense when considering that bacteria have and interdependency among them. (metabolically connected)

*Il-4 is the target of the new biologic dupilumab.

Bibliography: Signals from the gut microbiota to distant organs in physiology and disease.
Schroeder BO, Bäckhed F.
Nat Med. 2016 Oct 6;22(10):1079-1089. doi: 10.1038/nm.4185. Review.
Microbiome Changes and Effects on the Body .jpg
Gut Microbiome influences on the Human Body
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