Editors' ChoiceImmunology

Bad Cholesterol: Bad for Bacteria, Too?

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Science Signaling  12 Aug 2014:
Vol. 7, Issue 338, pp. ec213
DOI: 10.1126/scisignal.2005777

Why do viral infections, such as the common cold, leave people more susceptible to bacterial pneumonia? One reason is that type I interferons, secreted proteins that initiate antiviral immune responses, suppress other inflammatory molecules that protect against bacterial infection. Reboldi et al. investigated how this suppression occurs on a molecular level in mice. Interferons stimulated expression of a particular enzyme that catalyzes the production of the oxysterol 25-hydroxycholesterol (25-HC). 25-HC inhibits the function of the transcription factor SREBP, which normally drives expression of the gene that encodes interleukin-1, a secreted inflammatory protein with wide-ranging antibacterial functions.

A. Reboldi, E. V. Dang, J. G. McDonald, G. Liang, D. W. Russell, J. G. Cyster, 25-Hydroxycholesterol suppresses interleukin-1–driven inflammation downstream of type I interferon. Science 345, 679–684 (2014). [Abstract] [Full Text]