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On the Hook

A way that harmless and harmful bacteria in the gut are distinguished by our immune system

09 May 2019

On the Hook

Our gut plays host to a whole community of microbes, including many harmless commensals, that may even be beneficial. To avoid destruction by our immune system, they need to communicate with their host’s cells, and recent research may have uncovered a way for some bacteria to do this. Segmented filamentous bacteria closely associate with the intestinal epithelial cells lining the gut, latching onto them with a hook-like protrusion (pictured, as a computer reconstruction, overlaid onto a microscopy image). Electron microscopy revealed that membrane spheres, known as vesicles, are formed where bacterium and host meet, and carry antigens, protein markers of bacterial identity, back into the host cell. Antigens are typically used by the immune system to recognise and target foreign cells, but delivering them this way may alter the immune system’s reaction, protecting the bacteria. Nicknamed MATE, this ingenious process is revealing previously-unknown mechanisms for determining friend from foe.

Written by Emmanuelle Briolat

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BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

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