Studies show a link between breast milk, gut bacteria, and the development of the immune system

Many illnesses caused by dysregulation of the immune system, such as allergies, asthma, and autoimmunity, can be traced back to the first few months after birth. To date, the mechanisms behind the development of the immune system are not fully understood. Researchers at the Karolinska Institute in Sweden are now showing a link between breast milk, beneficial gut bacteria, and the development of the immune system.The study is published at cell.

A possible application of our results is a preventative measure to reduce the risk of allergies, asthma, and autoimmune diseases in later years by helping the immune system establish its regulatory mechanisms. We also believe that the specific mechanisms identified in this study may not only lead to prevention, but ultimately to the treatment of other types of such diseases. “

Peter Brodin, Study Last creator, PKarolinska Institute, Pediatrician, and Researcher in Women’s and Children’s Health

The incidence of autoimmune diseases such as asthma, type 1 diabetes, and Crohn’s disease is increasing in some children and adolescents worldwide. Although these diseases are debilitating, they are less common in low-income countries than in Europe and the United States.

It has long been known that the risk of developing these illnesses is largely determined by early life events. For example, there is a correlation between early use of antibiotics and an increased risk of asthma. Breastfeeding is also known to prevent most of these disorders.

There is a link between certain protective bacteria in the skin, respiratory tract, and intestines and a reduced risk of immune disorders. However, there is still much to learn about how these bacteria form the immune system.

Researchers at the Karolinska Institutet, Evolve Biosystems, Inc, University of California, Davis, University of Nebraska, Lincoln, and University of Nevada, Reno have found that the neonatal immune system adapts to many bacteria, viruses, nutrients, and other environments. I studied whether it is formed. Factors that expose babies in the first few months of life.

Previous studies have shown that bifidobacteria are common in breast-fed babies in countries with low rates of autoimmune disease.

Breast milk is rich in HMO (human milk oligosaccharides), so babies cannot metabolize it on their own. Instead, the production of these complex sugars is associated with the evolutionary benefit of nourishing certain gut bacteria that play important roles in the immune system. Bifidobacterium is one such bacterial class.

“We found that babies whose intestinal flora can destroy HMOs have less blood and intestinal inflammation,” says Professor Brodin. “This is probably due to the unique ability of bifidobacteria to break down HMOs, spread to lactating babies, and have beneficial effects on the development of the immune system early in life.”

Infants breastfed and treated with additional bifidobacteria had higher intestinal levels of ILA and galectin-1 molecules. ILA (indole-3-lactic acid) is required to convert HMO molecules into nutrients. Galectin-1 is central to the activation of the immune response to threats and attacks.

According to researchers, galectin-1 is an important newly discovered mechanism for preserving bacteria with beneficial anti-inflammatory properties in the gut flora.

The results are based on 208 breast-fed babies born at Karolinska University Hospital between 2014 and 2019. Researchers have also used a new method to analyze the immune system, even from small blood samples. In addition, in a second cohort developed by the University of California, babies were completely breastfed and half breastfed. B. Infantis Supplement Intestinal inflammation was analyzed.

One limitation of the study was that researchers could not study the immune system directly in the intestine and had to rely on blood samples. Not all aspects of the intestinal immune system are found in the blood, but performing an intestinal biopsy from a healthy newborn is ethically undefendable.

Researchers now want to keep track of participating babies longer to see which babies have atopic eczema, asthma, and allergies.

“We are planning a new experiment using bacterial substitutions to see if every baby can help start a healthier immunological life.” Professor Brodin says. “We are working with other researchers to compare the development of the immune system of Swedish babies and babies raised in sub-Saharan rural areas, where the incidence of allergies is much lower.”

This study was funded by the European Research Council, the Knut and Alice Warenberg Foundation, the Karolinska Institute, and the Swedish Research Council.

Petter Brodin, Axel Olin, Jaromir Mikes and Tadepally Lakshmikanth are the founders of Cytodelics AB in Sweden. Petter Brodin is an advisor to Scailyte AG in Switzerland. Ryan D. Mitchell, Stephanie Chew, Johann Prambs, Heather K. Brown, Steven A. Frese and Bethany M. Henrick have been featured in Evolve BioSystems. Jennifer T. Smithitz received a grant for the IMPRINT experiment, and Amy M. Ehrlich received funding to assist in writing the manuscript. Bruce J. German is a co-founder of Evolve BioSystems. Steven A. Frese is Bethany M. I’m Henrick and I belong to the Faculty of Food Science and Technology at the University of Nebraska-Lincoln, USA.