Giving cats a special food may one day help people with cat allergies | Science News for Students

Giving cats a special food may one day help people with cat allergies

Pet-food maker Purina is studying how adding an antibody to cat chow curbs allergic reactions
Aug 14, 2019 — 6:45 am EST
a photo of one cat licking another cat

Most cat allergies are triggered by a protein called Fel d1. It’s carried in cats’ saliva. New research aims to disable the protein at its source.

SunRay BRI Cattery RU/iStock/Getty Images Plus

Cat lovers who sneeze and sniffle around their feline friends might one day find at least partial relief in a can of cat food. This won’t be ordinary cat food, though. It will contain an antibody to the major allergy-causing protein in cats. This protein is called Fel d1. New research suggests that feeding its antibody to cats changes the protein so that the human immune system can’t recognize it. That reduces the allergic response.

Researchers fed the antibody to 105 cats for 10 weeks. After that, the amount of active Fel d1 protein on the cats’ hair dropped by 47 percent on average. Researchers from pet food–maker Nestlé Purina conducted the research. They reported their results in the June Immunity, Inflammation and Disease.

Nestlé Purina researchers also conducted a small pilot study with 11 people allergic to cats. These people were exposed in a test chamber to hair from cats fed the antibody diet. They were also exposed to hair from cats fed a normal, control diet. The people had reduced nasal symptoms and less itchy, scratchy eyes with the hair from cats fed the special diet. These preliminary findings were released in June. The researchers presented them in Lisbon, Portugal. They were at a scientific meeting called the European Academy of Allergy and Clinical Immunology Congress.

Lick, lick, lick

The Fel d1 protein is produced in cats’ salivary and sebaceous glands. Cats transfer the protein to their hair when they groom by licking themselves. They also excrete it in their urine. Humans are then exposed to the protein on cat hair and dander — dead skin — or in the litter box. Cat allergies plague up to 20 percent of people. Fel d1 is responsible for an estimated 95 percent of allergic reactions to cats.

Doctors can’t have humans consume these antibodies. That’s because the molecules are broken down in the gut. They would never reach their targets in the body, says Michael Blaiss. He is executive medical director of the American College of Allergy, Asthma and Immunology. He’s also an allergist and immunologist at the Medical College of Georgia in Augusta. Purina’s approach to the cat allergy problem is interesting and unusual, he says.

The antibody to Fel d1 is derived from eggs. It’s then added to cat food. In cats, it works in the mouth. There, it neutralizes the protein in saliva, says Ebenezer Satyaraj. He is director of molecular nutrition at Purina. He’s leading the cat allergen research. With this approach, the antibody disables Fel d1 “after its production by the cat, but before it spreads to the cat’s hair and dander — and before a response occurs in an individual sensitized to cat allergens,” says Satyaraj.

This approach doesn’t interfere with the normal production of Fel d1 by the cat, Satyaraj says. This is good because scientists aren’t sure how cats use Fel d1 in their bodies. Stopping its production could have unknown side effects. But so far, he adds, safety tests have found no harm to cats fed the antibody.

Blaiss expects that the new treatment may help people with mild cat allergies. But those with severe symptoms may be out of luck. They are unlikely to find relief from cutting the amount of active allergen only in half. Some people can’t tolerate any amount of the protein without symptoms, he says. What’s more, different cats can produce very different amounts of Fel d1 naturally. “So it just depends on the [Fel d1] levels of the cat and the symptomology of the patient,” he says.

In addition, Fel d1 is known to be a “sticky” protein, Blaiss says. It tends to stick around and accumulate in the home over time. So even if a person feeds their cat the antibody-laced food, “it could just take more time to build to a level that triggers an allergic reaction.”

Purina is not yet offering products containing the antibody, Satyaraj says. However, the company plans further research to determine how well it might work for reducing cat allergens in the home.

Power Words

(more about Power Words)

allergen     A substance that causes an allergic reaction.

allergy     The inappropriate reaction by the body’s immune system to a normally harmless substance. Untreated, a particularly severe reaction can lead to death.

antibody     Any of a large number of proteins that the body produces from B cells and releases into the blood supply as part of its immune response. The production of antibodies is triggered when the body encounters an antigen, some foreign material. Antibodies then lock onto antigens as a first step in disabling the germs or other foreign substances that were the source of those antigens. 

asthma     A disease affecting the body’s airways, which are the tubes through which animals breathe. Asthma obstructs these airways through swelling, the production of too much mucus or a tightening of the tubes. As a result, the body can expand to breathe in air, but loses the ability to exhale appropriately. The most common cause of asthma is an allergy. Asthma is a leading cause of hospitalization and the top chronic disease responsible for kids missing school.

average     (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

clinical     (in medicine) A term that refers to diagnoses, treatments or experiments involving people.

control     A part of an experiment where there is no change from normal conditions. The control is essential to scientific experiments. It shows that any new effect is likely due only to the part of the test that a researcher has altered. For example, if scientists were testing different types of fertilizer in a garden, they would want one section of it to remain unfertilized, as the control. Its area would show how plants in this garden grow under normal conditions. And that gives scientists something against which they can compare their experimental data.

dander     Flakes of skin in an animal’s fur or hair.

diet     The foods and liquids ingested by an animal to provide the nutrition it needs to grow and maintain health. (verb) To adopt a specific food-intake plan for the purpose of controlling body weight.

excrete     To remove waste products from the body, such as in the urine.

feline     Adjective for something having to do with cats (wild or domestic) or their behaviors.

gland     A cell, a group of cells or an organ that produces and discharges a substance (or “secretion”) for use elsewhere in the body or in a body cavity, or for elimination from the body.

gut     An informal term for the gastrointestinal tract, especially the intestines.

immune system     The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.

immunity     The ability of an organism to resist a particular infection or poison by providing cells to remove, kill or disarm the dangerous substance or infectious germ. Or, when used colloquially, it means the ability to avoid some other type of adverse impact (such as firing from a job or being bullied).

immunology     The field of biomedicine that deals with the immune system. A doctor or scientist who works in that field is known as an immunologist.

inflammation     (adj. inflammatory) The body’s response to cellular injury and obesity; it often involves swelling, redness, heat and pain. It also is an underlying feature responsible for the development and aggravation of many diseases, especially heart disease and diabetes.

molecule     An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

nasal     Having to do with the nose.

nutrition     (adj. nutritious) The healthful components (nutrients) in the diet — such as proteins, fats, vitamins and minerals — that the body uses to grow and to fuel its processes. A scientist who works in this field is known as a nutritionist.

physiology     The branch of biology that deals with the everyday functions of living organisms and how their parts function. Scientists who work in this field are known as physiologists.

plague     (verb) A common term for being beset by unpleasant conditions, events or circumstances — ones that cause serious impacts.  

preliminary     An early step or stage that precedes something more important.

protein     A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.

sebaceous glands     Structures in the skin that secrete oil. That oil can waterproof the skin and keep it from drying out.

side effects     Unintended problems or harm caused by a procedure or treatment.

symptom     A physical or mental indicator generally regarded to be characteristic of a disease. Sometimes a single symptom — especially a general one, such as fever or pain — can be a sign of any of many different types of injury or disease.

Citation

Meeting:​​ E. Satyaraj and H.J. Wedner. A novel approach to the reduction of cat allergen Fel d1 through inclusion of an egg product ingredient containing anti-Fel d1 IgY antibodies in the feline diet. European Academy of Allergy and Clinical Immunology Congress, Lisbon, Portugal, June 2019.

Journal:​ E. Satyaraj et al. Reduction of active Fel d1 from cats using an antiFel d1 egg IgY antibody. Immunity, Inflammation and Disease. Vol. 7, June 2019, p. 68.

Journal:​ E. Satyaraj et al. Anti-Fel d1 immunoglobulin Y antibody-containing egg ingredient lowers allergen levels in cat saliva. Journal of Feline Medicine and Surgery. Published online July 16, 2019.