Scientists Are Poised to Pounce on Cat Allergies

By Gina Wynn

Cat and dog allergies affect as many as three in ten people in the U.S. And twice as many people have allergic reactions to cats than they do dogs, according to the Asthma and Allergy Foundation of America. Even though cats may make us sneeze and our eyes itch, some of us still can’t resist having a feline furry friend in our lives. Sympathetic scientists and those who want to tap into a large market of suffering cat enthusiasts are investigating potential solutions.

Immunologists are working to improve allergy shots so they could provide patient relief in one dose. Some researchers are trying to develop vaccinations for cats instead of people that reduce their production of allergens. Other labs are experimenting with allergy-inhibiting cat food. The ultimate goal is to use gene editing to breed cats that don’t produce allergic reactions at all.

Why Do Cats Trigger Allergies?

All of these strategies for providing relief from teary eyes and runny noses focus on one protein — Fel d 1 — made in cats’ salivary and sebaceous glands. When cats lick themselves, it gets spread to their hair and skin. When the hair and flakes of dead skin, called dander, fall off the cat and spread around the house, there is no escaping the allergy trigger.

To make matters worse, dander is light, so it readily enters the air. It also sticks to people’s hair and clothes, so it easily gets transported to different locations. And it takes weeks or months to break down.

Allergy Proof Cat Breeds

Even though all cats produce Fel d 1, they have it in varying levels. That’s why some cats that produce less of the protein — like the Balinese, Oriental Shorthair, and Javanese breeds — are commonly thought of as hypoallergenic.

According to “The many efforts to lick cat allergies” by Erika Engelhaupt published on Science News for Students, Indoor Biotechnologies in Charlottesville, Virginia, tested hundreds of cats and found levels ranging from five to 2,000 micrograms of Fel d 1 per gram of fur. Scientists have identified variations in two different genes that can account for the range. But they have yet to figure out which gene versions result in low-allergen cats.

They also don’t know whether or not Fel d 1 serves a purpose for cats and if it plays a role in keeping cats healthy. Because a 1990 study published in the Journal of Allergy and Clinical Immunology found that big cats — including jaguars, pumas, Siberian tigers, snow leopards, and lions — produce a version of the protein, scientists believe it must have some value for cats to have retained it through evolution. 

What Are Traditional Treatments?

Traditionally, people have controlled their allergic reactions by taking antihistamines and other medications. These drugs only treat symptoms, however, and they don’t get rid of the allergy.

People can also treat cat allergies by getting a series of desensitizing injections. These work by introducing bits of the allergen into a person’s immune system so the body will make antibodies that block part of the allergic response.

“Desensitization therapy has been the only therapy for decades,” said Gerald Nepom, director of the Immune Tolerance Network in Seattle, Washington, as reported in Engelhaupt’s article. He added that it generally doesn’t eliminate all symptoms and the effects aren’t always permanent.

Another drawback to this type of immunotherapy is that it requires a major time commitment. It can involve as many as 100 vaccinations over the course of three to five years.

What New Methods Are Being Developed?

New approaches to taming cat allergies are turning to Fel d 1. Anyone who succeeds at manipulating the protein stands to make a big profit from allergic cat lovers the world over. Scientists are exploring these different avenues for developing an effective approach.

Improved Immunotherapy — Immunotherapy currently works by blocking your body’s production of histamines after an allergen has been discovered. A new study dubbed CATNIP funded by the Immune Tolerance Network involves an allergen-plus approach. Instead of allowing the histamine producing allergic response to be triggered, scientists are trying to stop the response from happening in the first place. They do this by combining small amounts of Fel d1 with an antibody that blocks a protein important to triggering the allergic response. If this method were to work, it would help patients develop a long-term tolerance from a year-long series of allergy shots.

Through another study published in 2018 by Nature Communications, researchers are hoping to perfect an immunization that will provide in one treatment results that would take years to achieve through traditional immunotherapy. Immunologists at Regeneron Pharmaceuticals in Tarrytown, New York, designed antibodies specific to Fel d 1 that bind to and lock up allergens before the immune system can react. A shortcoming to this method is that it doesn’t teach your body a new behavior; you would require boosters every few months to maintain the efficacy.

Allergy Shots for Cats — Or you could just vaccinate the cat against its own Fel d 1. A research team at HypoPet AG in Zurich, Switzerland, is taking this approach. The group published its findings in the Journal of Allergy and Clinical Immunology. They intersperse an inactive virus fragment with dozens of Fel d 1 molecules and inject it into a cat so the animal’s immune system will see the protein as an invader and produce antibodies against it.

“If you make the allergen look like a virus, the immune system thinks it is a virus,” said Martin Bachmann, chief scientific officer of HypoPet and Immunologist at the University of Bern in Switzerland, as reported in the Engelhaupt article.

The cat antibodies bound to the Fel d 1 would serve as a disguise that should make it unrecognizable to human immune cells. In a test of more than 50 cats, their secretion of the protein was reduced by more than half and the cats went unharmed.

Allergy-Inhibiting Cat Food — Nestlé Purina researchers at the Purina Institute in St. Louis, Missouri, are also working on an allergy-inhibiting strategy that acts on feline saliva without putting cats in danger. They are testing a cat food that contains an antibody that binds to the Fel d 1 in a cat’s saliva as it eats. Human immune systems aren’t able to recognize the altered protein when it ends up on a cat’s coat, so they produce less of an allergic reaction. So far, tests show that the amount of active allergen gets reduced by about half. This will be beneficial to people with mild to moderate allergies, but it won’t work for people with severe allergies.

Truly Hypoallergenic Cats — The best option for people with severe allergies is to own a cat that does not produce Fel d 1: a truly hypoallergenic cat. But breeders have not been consistently successful at crossing two cats low in Fel d 1 to bear kittens low in the protein. Researchers at Indoor Biotechnologies are turning to CRISPR/Cas9 gene editing techniques as a more reliable solution. Their method involves deleting two genes from cat cells called Ch1 and Ch2 that typically instruct cells on how to make Fel d 1. They then test to make sure the Fel d 1 is not being made. So far, the approach has worked in lab cell-culture dishes.

Eventually, the team hopes to be able to genetically engineer adult cats by employing a strategy currently used to edit the genes of people with sickle-cell disease. In their adaptation, the researchers would use a harmless virus to deliver gene-editing tools into a cat’s salivary glands or sebaceous glands in the skin. They will continue to experiment before this approach can become a reality, however, to ensure that the absence of Fel d 1 wouldn’t negatively affect the cats.

What the Future Holds for Allergy Sufferers

For cat lovers with cat allergies, these studies should provide more than a glimmer of hope. Now that Fel d 1 is accepted as the root of cat people’s misery, it’s only a matter of time before an allergy-eradicating discovery is made. And you’ll be able to lead the sneeze-free life with your cuddly companion that you’ve always dreamed of.