Adding an asthma therapy to allergy shots may help tame cat allergies. A new combination treatment reduced allergy symptoms. And its relief lasted for a year after people stopped getting the shots.
Allergies rile up the immune system. That creates irritating symptoms: itchy eyes, sneezing, runny nose, congestion and more. For more than a century, allergy shots — also called immunotherapy — have been used to reduce such symptoms. The shots contain tiny amounts of the things people are allergic to, called allergens. People get shots weekly to monthly for three to five years. This gradually builds a tolerance to the allergen. The treatment can essentially cure some people of their allergies. But others never see an end to needing the shots.
Scientists still don’t know exactly how allergy shots work, says Lisa Wheatley. She’s an allergist at the National Institute of Allergy and Infectious Diseases. It’s in Bethesda, Md. Allergy symptoms will get better after a year of receiving shots. But stop after that year and those benefits disappear, she says.
Wheatley is part of a team that wanted to improve allergy therapy. They hoped to reduce the amount of time shots were needed while also giving patients long-lasting relief. The team also hoped to better understand how immunotherapy works.
Immune system alarm bells
When allergies strike, some immune cells produce alarm chemicals. They trigger symptoms including inflammation. It’s one of the body’s distress responses. Too much inflammation can be dangerous. It can cause swelling and make breathing difficult. “If we could dampen the signaling that says ‘danger,’ we could maybe improve immunotherapy,” Wheatley says.
She and colleagues turned to antibodies. Those proteins are part of the immune system’s response to things it sees as dangerous. The team used a lab-made antibody called tezepelumab (Teh-zeh-PEL-ooh-mab). It blocked one of those alarm chemicals. This antibody has already been used to treat asthma. So Wheatley’s team knew it is generally safe.
They tested the antibody on 121 people with cat allergy. Dander — a protein in cats’ saliva or dead skin cells — causes them beastly symptoms. The team gave participants either standard allergy shots alone, the antibody alone, both of those or a placebo. (A placebo doesn’t contain any medicine.)
A year later, the team tested participants’ allergic response. They squirted cat dander up the noses of these people. On its own, tezepelumab was no better than a placebo, the researchers found. But people who got the combo had reduced symptoms compared with those who got standard shots.
The researchers shared these findings October 9 in the Journal of Allergy and Clinical Immunology.
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Quieting allergy triggers
The combination treatment dropped levels of allergy-triggering proteins. These proteins are known as IgE. And they kept falling even a year after treatment ended. But in people who got only the standard shots, Wheatley notes, IgE levels started to claw their way back up once the treatment stopped.
The team swabbed participants’ noses for clues to why the combo therapy may work. It alters how active some genes in immune cells are, they found. Those genes were related to inflammation. In people who got the combo therapy, those immune cells made less tryptase. That’s one of the major chemicals released in an allergic reaction.
The results are encouraging, says Edward Zoratti. But he says it’s not clear that this antibody would work as well for other allergies. He wasn’t part of this work, but he does study allergies and the immune system at Henry Ford Hospital in Detroit, Mich. He wonders: “Did they just get lucky and choose the right allergen?”
Cat allergies develop against a single sticky antigen. It’s a protein known as Fel d1. It’s found in cats’ saliva and dander. Cockroach allergies, in contrast, can be produced by a variety of proteins. So the combo therapy might not work as well for those allergies.
Also, Zoratti says, the type of antibodies that the new study used (monoclonal antibodies) are pricey. That’s another possible drawback.
Much more research is needed before this therapy is added to allergy shots in a doctor’s office, he says. But the study is important for understanding how allergy therapies work. And, he adds, “It’s one step in a long chain that will probably lead us to a really useful therapy in the future.”