Human goblet cell. Image courtesy of the University of Edinburgh, Wellcome Images
Raise a glass to the goblet cell
In a paper published last week in Virology Journal, Pascal Gagneux and colleagues at UC San Diego School of Medicine describe how influenza A viruses snip through the protective mucus net to both infect respiratory cells – and then later cut their way out infect other cells.
Mucus is usually deemed a disgusting annoyance, but really it’s not. (Sorry, couldn’t resist.) It is oil in the human engine, lubricating the passages of the mouth, nose, sinuses, throat, lungs and gastrointestinal tract, preventing underlying epithelial tissues from drying out. It’s also a sort of sticky flypaper, trapping unwanted substances like bacteria and dust before they can too deeply penetrate the fairly pristine and sterile inner body.
Each day, a healthy person churns out about 4 to 6 cups of mucus. Most of it trickles down your throat unnoticed. The little factories that make mucus are called goblet cells. It’s an apt moniker because goblet cells are little more than vessels filled to the brim with globules of mucin. That’s a globule cell in the image above; the mucin globules colored blue.
Mucins are glycosylated proteins, but you can think of them more simply as dehydrated bits of mucus packed inside a globule cell. Once released into the water-rich environment of your airways, however, they expand rapidly, absorbing water to reach full, gooey size within 20 milliseconds. That’s one-thousandth of a second. That’s fast. A single flap of a hummingbird’s wing takes 5 to 80 milliseconds.
The rapid release allows goblet cells to respond almost instantly to many different stimuli, from inhaled microbes to a mouthful of eye-watering wasabi.