An internal clock regulates inflammation in mouse lungs.
Symptoms of some human lung diseases, including asthma, tend to vary in severity according to the time of day. Andrew Loudon and David Ray at the University of Manchester, UK, and their colleagues found that immune responses to a bacterial toxin are regulated by a circadian clock in mouse lungs. The recruitment of immune cells called neutrophils and the expression of several immune-related proteins responded rhythmically to the toxin, with neutrophil recruitment peaking at dawn.
Deleting a key 'clock gene' weakened responses to bacterial infection and reduced the effect of glucocorticoid steroids, which normally suppress inflammation. Chronic lung inflammation could be partly caused by circadian disruption, the authors say.
Nature Med. http://dx.doi.org/10.1038/nm.3599 (2014)