Tag: eczema

Categories : Allergies DermatologyTags : Leave a comment

Can Early Exposure to Dogs Lessen Genetic Susceptibility to Eczema?

On By ModernMedia
Photo by Pauline Loroy on Unsplash

New research published in Allergy indicates that certain environmental exposures may affect a child’s risk of developing atopic eczema, a condition characterised by dry, itchy, and inflamed skin. In other words, although some people may be genetically predisposed to eczema, certain environmental factors may increase or decrease that risk.

For the study, investigators analysed data from 16 European studies to test for interactions between the 24 most significant eczema-associated genetic variants and 18 early-life environmental factors. They applied their findings to an additional 10 studies and used lab modelling tests to assess their results.

The first analysis (including 25 339 individuals) showed suggestive evidence for interaction between 7 environmental factors (antibiotic use, cat ownership, dog ownership, breastfeeding, elder sibling, smoking, and washing practices) and at least one established genetic variant for eczema, with 14 interactions in total.

In the additional analysis (254 532 individuals), dog exposure interacted with a particular genetic risk variant on chromosome 5, near the gene that codes for the interleukin-7 receptor, a protein involved in immune cell function. Lab modelling tests showed that this variant affects expression of interleukin-7 receptor in human skin cells and that dog exposure modifies the genetic effect of this variant on the development of eczema, essentially providing a protective effect by suppressing skin inflammation.

Additional studies are needed to explore these lab findings and the other potential interactions identified in the first analysis.

“Our research aims to answer some of the most difficult questions that I am asked in clinic: ‘Why does my child have eczema?’ and ‘What can I do to help protect my baby?’ We know that genetic make-up affects a child’s risk of developing eczema and previous studies have shown that owning a pet dog may be protective, but this is the first study to show how this may occur at a molecular level,” said corresponding author Sara J. Brown, MD, PhD, FRCPE, of the University of Edinburgh. “More work is needed, but our findings mean we have a chance to intervene in the rise of allergic disease, to protect future generations.”

Source: Wiley

Categories : Allergies T-cellsTags :

Itching in Severe Eczema Uses a Different Pathway

On By ModernMedia

A study shows that there are two molecular pathways for conveying sensations of itching, with the itching of severe eczema following an unexpected route.

In normal eczema, cells in the skin convey the itching sensation, releasing histamines. This can be blocked with antihistamines.

“Years ago, we used to think that itch and pain were carried along the same subway lines in the nerves to the brain, but it turned out they weren’t, and these new findings show there’s another pathway entirely that’s causing these episodes of acute itching in eczema patients,” said principal investigator Brian S Kim, MD, Washington University School of Medicine. “The itch can be maddening. Patients may rate their chronic itch at around a 5 on a scale of 10, but that goes up to 10 during acute itch flares. Now that we know those acute flares are being transmitted in an entirely different way, we can target that pathway, and maybe we can help those patients.”

With severe itching in eczema, different cells in the blood are activated, transmitting great quantities of non-histamine molecules which also convey the itching sensation. This renders antihistamines usesles in trying to control the itch. The discovery of this new pathway offers new possibilities for treating other conditions as well. Recent studies have tried to block Immunoglobulin E (IgE) in response to allergies.

“We’ve connected acute itching in eczema to allergic reactions transmitted by an entirely different population of cells,” explained Kim. “In patients who experience episodes of acute itching, their bodies react in the same way as in people with acute allergy. If we can block this pathway with drugs, it might represent a strategy for treating not only itch but other problems, including perhaps hay fever and asthma.”

The team found that when mice with eczema made IgE in response to environmental allergens, they began to itch. However, instead of activating mast cells which produced histamine, the IgE activated basophils (a kind of white blood cell), activating a different nerve pathway to normal itching.

The discovery that eczema is exacerbated by allergens may help people avoid severe itching episodes, as well has helping the development of new targets for treatment.

Source: News-Medical.Net

Journal information: Wang, F., et al, A basophil-neuronal axis promotes itch. Cell, 2021 doi.org/10.1016/j.cell.2020.12.033.