Some people can fend off influenza infection; others have a severe, sometimes fatal, inflammatory reaction. Researchers in La Jolla, California, have pinpointed a cellular mechanism that prompts this 'cytokine storm'.

Inflammation is triggered by immune-signalling proteins called cytokines. Michael Oldstone and Hugh Rosen at the Scripps Research Institute and their teams had previously shown that stimulating cell receptors for a lipid signalling molecule called S1P dampens the cytokine storm. The current study reports that, in mice, this is mediated by a specific receptor, S1P1, that is expressed in the cells lining the blood vessels of the lungs. Treating flu-infected mice with an S1P1-stimulating molecule decreased both their cytokine production and the number of inflammatory cells migrating into their lungs, and improved their survival.

The findings could be relevant to other viral infections, as well as to autoimmune diseases.

Cell 146, 980–991 (2011)