Immune-cell study traces a failure between engulfing bacteria and killing them
A peer-reviewed laboratory study links the movement and fusion of internal compartments to bacterial killing by neutrophils, an early-response immune cell. Experiments with mouse cells lacking the WASH protein found that engulfing microbes could continue while later processing failed. A second protein, syntaxin 19, helped connect this internal transport machinery to compartment fusion.
Science··Midday
Engulfed bacteria survived more readily
A peer-reviewed laboratory study in Nature Communications examines neutrophils, immune cells that respond early to infection. In experiments using mouse cells lacking WASH, a protein that helps organise the cell’s internal scaffolding, the cells still engulfed bacteria. Their ability to kill bacteria once inside was impaired. The difference appeared with two bacterial species, locating the problem beyond the initial capture of a microbe. The experiments concern cellular mechanisms rather than treatment tested in people.[1]
Internal compartments failed to join
After capture, bacteria sit within a membrane compartment called a phagosome. This normally joins lysosomes, the cell’s compartments containing breakdown machinery. Imaging showed that loss of WASH reduced movement of these internal compartments and disrupted their fusion. The bacteria-containing space also became less acidic. Restoring movement alone did not restore later processing, pointing the researchers towards another part of the fusion machinery.[1]
A second protein connects transport and fusion
The team identified syntaxin 19, a membrane-fusion protein that interacts with WASH. It was missing from isolated bacteria-containing compartments in cells without WASH. Interfering with syntaxin 19 also disrupted compartment maturation without preventing particle uptake. These findings describe separate steps in the immune cell’s response: bringing a microbe inside and supplying the internal machinery needed to break it down.[1]
