High-tech tissue study reveals cells that cause painful food allergy

CINCINNATI – An eight-year-old hunt for cells at the origin of eosinophilic esophagitis (EoE), an extreme food allergy in children, has helped identify a new way to treat disease while by raising questions about a dietary supplement often taken to reduce intestinal inflammation.

The study, led by experts from the Cincinnati Children's Hospital Medical Center, is available online in the Journal of Clinical Investigation and will be released in May. The work was led by first author Ting Wen, MD, PhD, and by lead author, Marc Rothenberg, MD, PhD, director of the Division of Allergy and Immunology.

The reported cases of EoE have risen sharply over the last two decades, now affecting up to one in 2,000 people. This permanent allergic disease occurs when too many eosinophils (a type of white blood cell) cause inflammation making swallowing and feeding painful. The EoE can be so serious that some people depend on special liquid formulas for food.

Rothenberg's work over the years has helped make EoE its own disorder, while Cincinnati Children's has become the leading center for treatment and study of the disease in the country. Clinical teams here help patients achieve better levels of remission, while lab teams explore the genetic and molecular pathways that can eventually lead to even better drugs.

In this study, Wen and Rothenberg developed and perfected a 10 to 12-hour process that isolates and badyzes individual living cells from human tissue samples the size of three sesame seeds.

"It is actually a substantial advance for the field," Rothenberg said. "Previous work has focused on blood cells, but not memory-specific immune cells in tissues that respond directly to food allergens, and we have discovered the unknown properties of these cells."

Their main conclusions:

• Eight types of T cells of the immune system have been found in the esophageal tissue. It's more than previously planned.
• Two types of cells (T7 and T8) appear in greater numbers in the diseased tissue. The study shows that one of these two types of cells reacts to allergens by producing huge amounts of type 2 cytokines responsible for inflammation.
• One of these types of cells (T8) is almost non-existent in healthy tissue, making it a particularly interesting goal for treatment. "These cells are bad actors that should not be in this type of tissue.Inhibiting these cells is now a central focus of our research," Wen said.
• So how did these bad players get here? The study of this issue led the coauthors to a surprising discovery. One of the hyperactive genes that helps trigger the inflammatory response – a gene called FFAR3 – also encodes a receptor for a dietary supplement called butyrate.

Good for the lower digestive tract, not so much for the upper tract

Butyrate is a short chain fatty acid sold online and at many health food stores, without a prescription. In the colon, this fatty acid helps the body to produce energy from dietary fiber. It also appears to prevent or reduce inflammation in the lower digestive system, making the supplement popular among people with inflammatory bowel disease.

But in the esophagus, at the upper end of the digestive system, this otherwise beneficial fatty acid can cause or worsen the EoE by activating the newly identified population of cytokine-producing T cells, explain the co-authors.

Other studies are needed to answer such questions as: Do patients with EoE worsen their own conditions while taking butyrate? Does butyrate intake for a problem in the lower digestive tract increase the risk of developing a rash? Do butyrate supplements need warning labels?

"It is far too soon to say under what conditions butyrate could be harmful," says Rothenberg. "But this initial discovery deserves further exploration."

A race to the results

A growing number of scientists are using single-cell RNA technology to study various diseases. This is the first study to use single-cell RNA sequencing to collect data from cells hiding in EoE-affected tissues.

As part of this project, study participants were expected to arrive early in the morning to allow doctors to remove a flake of tissue the size of three sesame seeds. These samples were sent to the laboratory where Wen minutely isolated more than 1,000 targeted cells, each suspended in its own microchamber on a special plastic chip. Then, the team used RNA sequencing to profile the entire genome, cell by cell.

Each donor patient launched a one-day marathon on cell therapy in which 19 professionals participated. "There were days when people literally sent samples from the clinic to our lab, and people often agreed to work late into the evening to complete the process," says Wen. "It was really a team science in action."

The method can also help to study asthma and other ailments

Beyond the EoE, the process used in this study could be applied to other more common conditions to find small populations of cell culprits hiding in the tissues. The co-authors of the study claim that this process could be useful in the study of asthma, atopic dermatitis, allergic rhinitis and other diseases badociated with cytokines. type 2.

"I've already been contacted by other labs interested in using this platform to study tissue-resident cells," Wen said.

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This study was funded by the National Institutes of Health (P30 DK078392, U19 AI070235, R01 AI124355, R37 A1045898); the HOPE Research Grant (APFED); the Sunshine Charitable Foundation, and its supporters Denise and David Bunning; and the long-term support of the CURED Foundation.

A patent application relating to the discoveries of FFAR3 and T8 cells has been filed. Rothenberg and Wen are also listed as inventors of other patents owned by Cincinnati Children & # 39; s. Rothenberg's advisory and fairness roles are also described in the JCI article.