By Anne Crawford+61 3 9903 0026
June 18, 2022

A Monash University collaboration found that eosinophils, a type of white blood cell commonly associated with asthma and allergies, play an important role in maintaining a healthy gut.

Professor Nicola Harrisfrom the Central Clinical School at Monash, made the startling discovery while working with study co-lead, Professor Kathy McCoy from the University of Calgary and scientists from Switzerland. Their paper was posted in Immunity June 16.

“The study showed an essential role for eosinophils in facilitating mutualistic interactions between the host and the microbiota, the millions of bacteria in the gut,” Professor Harris said. “This upends our view of eosinophil function and will undoubtedly stimulate much more research into these relatively rare cells,” she said.

Eosinophils make up about 1-2% of circulating white blood cells in healthy people in developed countries, but are present in increased numbers in people with severe allergies. “They play a tissue-destroying pathological role in these allergies, they’re the bad guys,” Professor Harris said.

About 10-15 years ago, scientists realized that eosinophils made up 10-30% of white blood cells in the gastrointestinal tract and asked why. The answer has remained a mystery, Professor Harris said. “We sought to understand why these supposed tissue-destroying cells were in the gut.”

Scientists investigated the possible role of eosinophils in key functions of the small intestine using germ-free animal models and advanced 3D microscopy. They discovered that eosinophils coordinated the gut’s response to bacteria.

“They limited overt inflammation and in doing so limited tissue damage,” Professor Harris said. “The most important factor in this damage is the length of the villi, the finger-like projections that come up from the wall of the intestine, which absorb nutrients.

“We found that eosinophils kept these villi intact and without them the villi became much shorter and lipid absorption was reduced.

“So they were helping to maintain that absorption zone that allowed the extraction of nutrients from the diet at an appropriate level.”

The study also revealed that intestinal motility was dysregulated in the absence of eosinophils and that they could impact tissue structure.

“These cells are much more complicated than previously thought – we have to think about it in an entirely different way,” said Professor Harris. “They do a lot of things that are completely unexplored.”

Professor Harris said the results had many implications for those who study cells in the fields of clinical and basic research.

The co-first authors of the paper were Dr. Aline Ignacio from the University of Calgary and Dr. Kathleen Shah from the Global Health Institute, Swiss Federal Institute of Technology, Lausanne, Switzerland.

Reference

Aline Ignacio, Kathleen Shah, Jeremiah Bernier-Latmani, …, Nicola L. Harris, Kathy D. McCoy. Resident eosinophils of the small intestine maintain intestinal homeostasis after microbial colonization. Immunity, June 15, 2022. DOI: https://doi.org/10.1016/j.immuni.2022.05.014

About Monash University

Monash University is Australia’s largest university with over 80,000 students. In the 60 years since its founding, it has established a reputation as a world leader in high-impact research, quality teaching and inspiring innovation.

With four campuses in Australia and a presence in Malaysia, China, India, Indonesia and Italy, it is one of Australia’s most internationalized universities.

As a leading international medical research university with Australia’s largest medical school and integrated with Australia’s leading teaching hospitals, we consistently rank among the world’s top 50 universities for clinical, preclinical and health.

For more news, visit Medicine, Nursing and Health Sciences Where Monash University.

MEDIA INQUIRIES

Email: [email protected]