Y Zhou

Inside every cell there are waste-recycling stations: lysosomes. To digest the trash, they need an acidic environment, and the acid is pumped in by a molecular pump called V-ATPase. With age this pump works more and more weakly, and lysosomes stop keeping up. But the bacteria living in the gut have their own building material, peptidoglycan, and as it turns out, it can serve as a key that restarts the pump.

An old house stands because a repair crew lives in it. Spot a crack in the wall, patch it, paint it over, and the building takes a hit again. In the eye, that crew is a set of immune cells that gather around the drainage channel and keep pressure from climbing. As we age, the channel that drains fluid from the eye narrows, like an aging pipe.