Collaboration Unveils Bacteria Protecting Against Cow’s Milk Allergy

Understanding Food Allergies

Food allergies represent an adverse reaction occurring when the immune system mistakenly identifies certain food components as threats. This response can lead to various health issues. Research suggests a rising prevalence of food allergies, particularly over the last two to three decades, with cow’s milk allergy being the most common among infants.

Prevalence in Industrialized Countries

Food allergies are notably more common in industrialized nations and tend to affect children more than adults. Despite global dietary diversity, severe allergies primarily arise from a limited selection of food items, including peanuts, tree nuts, fish, shellfish, eggs, milk, wheat, soy, and seeds.

Factors Influencing Food Allergies

The emergence of food allergies, like other chronic diseases, is influenced by a combination of genetic and environmental factors. While aspects such as sex, ethnicity, and genetics are beyond our control, we can focus on modifiable risk factors. Adjustments in hygiene practices, dietary choices, and addressing vitamin D deficiency may help reduce allergy risks.

The Role of Gut Microbiota in Food Allergy

Intestinal Microbiota Composition

The human intestinal microbiota, consisting of various microbes, plays a crucial role in processing food and generating beneficial nutrients, including vitamins. Studies indicate that the microbiota’s composition may significantly affect the occurrence and resolution of food allergies.

Research on Cow’s Milk Allergy

A study examining cow’s milk allergy revealed distinct differences in the bacterial species present in the feces of allergic infants compared to their healthy peers. Collaborative research between the University of Naples Federico II and the University of Chicago sought to explore the protective effects of specific bacteria against cow’s milk allergy, with findings recently published in Nature Medicine.

Microbial Transplantation in Allergy Research

Experimental Design

Researchers isolated intestinal microbes from eight infants, half with cow’s milk allergy and half healthy. These microbes were transplanted into germ-free mice, which were raised in a sterile environment lacking their own microbiota. The mice were fed a formula similar to what the infants consumed, alongside standard mouse food.

Results of the Experiment

The allergy levels were tested in both groups of mice. Those receiving microbes from allergic infants exhibited severe reactions to cow’s milk, while mice receiving microbes from healthy infants did not show any allergic responses. A control group of germ-free mice also reacted severely, underscoring the protective effect of gut microbes from healthy infants.

Identifying Protective Bacteria

Further analyses aimed to discern differences in gene expression between the two groups of microbes, leading to the identification of the bacteria Anaerostipes caccae as a key species that protects against cow’s milk allergy. Subsequent experiments demonstrated that mice colonized solely with A. caccae did not experience severe allergic reactions, affirming its protective role.

Implications for Preventing Food Allergies

Future Strategies for Modulating Gut Microbiota

This study reinforces the hypothesis that gut microbiota significantly influences food allergies. The findings highlight that microbes from healthy children can confer protection against cow’s milk allergy when transplanted into mice. The isolated A. caccae is notable for producing butyrate, a substance that nourishes colon cells and supports a healthy intestinal microbiome. These insights pave the way for future strategies aimed at modifying gut microbiota composition to prevent food allergies.

References

Feehley, T., Plunkett, C. H., Bao, R., Hong, S. M. C., Culleen, E., Belda-Ferre, P., Campbell, E., Aitoro, R., Nocerino, R., Paparo, L., Andrade, J., Antonopoulos, D. A., Berni Canani, R., & Nagler, C. R. (2019). Healthy infants harbor intestinal bacteria that protect against food allergy. Nature Medicine.
Blázquez, A. B., & Berin, M. C. (2017). Microbiome and food allergy. Translational Research. NIH Public Access. 179, 199-203.
Sicherer, S. H., & Sampson, H. A. (2018). Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management. Journal of Allergy and Clinical Immunology, 141(1), 41–58.