Male FVB mice (6 to 8 weeks old) purchased from Charles River Laboratories were fed ad libitum Laboratory Rodent Diet 20–5058 (Lab Diet, Purina Mills). Animal experimental procedures were approved by the Standing Committee on Animals of Harvard Medical School (protocol no. 02570) and complied with institutional and US National Institutes of Health (NIH) guidelines. Mice were given vehicle together with live E. coli (serotype O6:K2:H1; 107 CFU) or saline injections (mock infection) i.p. After 12 h, mice were euthanized and the peritoneal exudate was collected, see reference 29 (link) for details. The local eicosanoid levels and identification PTAD-products were assessed by targeted lipid mediator metabololipidomics as described below.