A study outlines why antihistamine drugs often do not work to control true itch

In addition to skin broth, many people who suffer from eczema also get a chronic itch, but sometimes itching can be fertile. Worse, antihistamines – the usual treatment for itching and allergies – often do not help.

A new study from the University of Washington School of Medicine in St. Louis points out that allergens in the environment are to blame for the occurrence of itchy hunger in eczema patients, and that the itch often does not respond to antihistamines because the itch signals are transported to the brain in an unknown route previously conventional drugs are not targeted.

The new findings, published on January 14 in the journal Cell, identify a target and a possible new strategy to help eczema patients deal with those times of severe itch.

Years ago, we used to think that itch and pain were carried along the same underground lines in the nerves to the brain, but it turned out that they were not, and the co These new findings show that there is a completely different pathway that causes these times of severe itching. in eczema patients. The itch can be horrible. Patients may rate the itch as harmful at around 5 on a scale of 10, but that goes up to 10 during foot flares. Now that we know that these grim flames are delivered in a completely different way, we can focus on that path, and perhaps we can help these patients.. “

Brian S. Kim, MD, Principal Investigator and Dermatologist and Associate Professor of Medicine, University of Washington School of Medicine

The usual route for itching in eczema patients involves activating skin cells and then releasing histamine, which can be blocked by drugs antihistamine. But with this severe itch, a different type of cell in the bloodstream sends itch signals to the nerves. These cells make too much of another non-histamine substance that stimulates itch; therefore, antihistamines will not work in response to these symptoms.

“We have linked acute itching in eczema to allergic reactions transmitted by a completely different population of cells,” said Kim, who is also co-director of the Center for the Study of Itch & Sensory Disorders. “In patients who experience chronic illnesses, their bodies react in the same way as people with allergies. If we can block this pathway with drugs, it may be ‘represents a strategy for treating not only itch but other problems, possibly including hay fever and asthma. “

In recent years, several clinical studies have demonstrated a strategy that includes inhibition of Immunoglobulin E (IgE), a substance produced by the immune system in response to allergens. Patients with allergies produce IgE, causing an allergic reaction, but its role in itch is unclear.

Examining data from clinical studies of drugs aimed at treating chronic itching, Kim found a pattern in which patients reported incidents of acute itching, often after exposure to environmental allergens. He also found that eczema patients who produce IgE in response to allergens in the environment were more likely to experience those moments of severe itch.

“Environmental allergens trigger this type of itch,” he explained. “Say a patient with eczema goes to Grandma’s house, where there is a cat, and that person’s itching is just crazy. Cat dander appears to activate IgE, and IgE activates itch. “

Kim’s team took these ideas to the lab, where her team made a mouse model of eczema. Examining the animals, they found that when the mice produced IgE, they began to thatch. But unlike normal itch symptoms, in which cells in the skin called mast cells release histamine, the IgE in mice with eczema activated a type of white blood cell called basophil. These cells then implanted a completely different set of zero cells than the cells carrying itch signals that respond to antihistamines.

Finding out that itchy hunger in eczema is linked to exposure to allergens can help avoid things that cause itch severely, including animals, dust, mold or special food. At the same time, it also offers drug companies new targets for treating itch in eczema patients, including proteins and molecules that Kim’s team has identified on the neuro pathway. this newly identified protective.