Key Immunologic Mechanism in Regulation of the Intestinal Flora Discovered



Immunoglobulin M (IgM) secreted by the human intestine interacts with the intestinal microbiota and plays an active role in maintaining its diversity.

The microbiota or intestinal flora is currently one of the most promising areas of research, as there are some 100 billion bacteria living in our bodies that are essential for our health and play a fundamental role in many of the processes that take place in our bodies.

The immune system is key to controlling the microbiota, eliminating organisms that may be harmful and tolerating others that are beneficial. One of the most widely studied and understood immunologic factors to date in the regulation of the intestinal microbiota is immunoglobulin A (IgA). This molecule is secreted in the intestinal mucosa and prevents harmful bacteria from penetrating our bodies.

Researchers of the IMIM B-Cell Research Group have discovered that, as well as IgA, immunoglobulin M (IgM) secreted by the human intestine, interacts with the intestinal microbiota and plays an active role in maintaining its diversity. They have also shown that this immunoglobulin forms part of an immunological memory system by means of which our bodies are able to recognize and adapt to their microbial environment.


Immunoglobulins are proteins that act as antibodies and protect the body from the different micro-organisms and foreign bodies that invade it. But not all micro-organisms are harmful: it has been calculated that our intestines are home to millions of micro-organisms that provide numerous benefits to our health. These micro-organisms include bacteria, viruses and fungi, and are also known as the intestinal flora or microbiota. A healthy and balanced intestinal microbiota is essential to maintaining intestinal health and nutrient absorption, and its dysfunction may contribute to the appearance of different diseases.

Another conclusion of this study is that IgM not only acts as an agent for excluding and eliminating micro-organisms but also plays an active role in including and maintaining micro-organisms that are beneficial for our health. This provides key information for the subsequent study of the factors involved in the development and evolution of all diseases associated with abnormalities in the microbiota.

In recent years, it has been shown that an imbalance in the microbiota may play a role in the development and evolution of different diseases, such as Crohn and ulcerative colitis, and in metabolic diseases such as obesity and diabetes, allergies and auto-immune diseases, and even some types of cancer.


Reference article

Magri G, Comerma L, Pybus M, Sintes J, Lligé D, Segura D, Bascones S, Yeste A, Grasset EK, Gutzeit C, Uzzan M, Ramanujam M, van Zelm MC, Albero R, Vazquez I, Iglesias M, Serrano S, Marquez L, Mercade E, Mehandru S, Cerutti A. Human Secretory IgM Emerges from Plasma Cells Clonally Related to Gut Memory B Cells and Targets Highly Diverse Commensals. Immunity 2017; 47: 118-134.



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