Constrained and Restrained

Some macrophages [a type of immune cell] circulate in the blood like patrolling soldiers on the lookout for invaders. But others are more akin to stationed sentinels, residing long-term within tissues, inactive but ever-ready. Unlike their circulating counterparts, these tissue-dwelling cells are not easily rallied by inflammatory signals, remaining inactive until the fight (tissue damage) comes to their door. While, this inactivity has benefits, ensuring tissues don’t become unnecessarily inflamed, how it’s controlled was unclear. Now scientists have found that the spatial constraints of the tissue keep the cells in check. This electron microscope image (false coloured) shows a macrophage sequestered in an artificial pore, which reduces the cell’s ability to spread out – an intrinsic part of activation. The discovery not only explains why tissue-resident macrophages remain dormant, but may also inform the design of medical implants, which if given porous surfaces might reduce inflammatory reactions.

Written by Ruth Williams

Ruth Williams

Writer

Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

Website

• Image by Nikhil Jain and Isabel Gerber, ETH Zurich
• Laboratory of Applied Mechanobiology, Institute of Translational Medicine, Department of Health Sciences and Technology, ETH Zurich, Switzerland
• Image copyright held by the original authors
• Research published in Nature Materials, October 2018