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Publications of the Week

Commensal Bacteria Modulate Immunoglobulin A Binding in Response to Host Nutrition

By April 23, 2020No Comments

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This week we profile a recent publication in Cell Host & Microbe from Kelsey Huus
in the laboratory of Dr. Brett Finlay at the Michael Smith Laboratories at UBC.

Can you provide a brief overview of your lab’s current research focus?

The Finlay lab focuses on understanding how intestinal microbes cause health and disease. We’ve traditionally studied diarrheal pathogens like Salmonella and E. coli, but an emerging research interest of the lab is how the complex microbial community (or ‘microbiota’) of the gut contributes to intestinal health. We’re studying how this microbiota impacts not only diarrheal diseases but also child malnutrition, allergy and asthma, and even neurological diseases like Parkinson’s. The work recently published focused on intestinal bacteria in early life malnutrition.

What is the significance of the findings in this publication?

This study found differences in how healthy intestinal bacteria interact with the immune system in malnutrition. Child malnutrition is a huge global health issue that is linked not only to poor diet, but also to poor sanitation and the intestinal microbiota. We know that interactions between the immune system and the intestinal microbiota early in life are really important for long-term health, so we’ve been studying how the main antibody in the gut, IgA, recognizes gut bacteria. We found that in malnourished mice, the probiotic bacterium Lactobacillus went into ‘starvation mode’ and stopped interacting with host antibody. This is important because there is a lot of interest right now in using Lactobacillus to treat malnourished kids, and if this bacterium stops interacting with the immune system during malnutrition, it might affect its ability to be a successful probiotic.

What are the next steps for this research?

We’ve shown that Lactobacillus changes its interaction with the immune system, but so far we don’t really understand how this impacts host health. So although we can speculate, one of the most important questions remaining is how this loss of interaction between Lactobacillus and antibody actually affects malnutrition or disease outcomes: this will be key to address going forward. Another important unknown is whether these findings in mice are applicable to human populations or not. A study from another group has suggested that malnourished children tend to have less IgA recognition of beneficial bacteria, so it could be quite relevant. We’ve got some work of our own underway looking at bacterial-immune interactions in a human population (via the ‘Afribiota’ project which is run by the Pasteur Institute), but these results aren’t out yet.

This work was funded by:

This work was funded by grants from the Canadian Institute for Health Research and the Bill and Melinda Gates Foundation. The lead author, Kelsey, was also funded by a Vanier Graduate Scholarship and by a Killam Graduate Scholarship.

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