UCP2 and listeriosis: This is supported by studies showing that UCP2/3 overexpressing mice have reduced inflammatory responses after endotoxin challenges and decreased IL-6 and IL-4 levels after lipopolysaccharide challenge [24] and that UCP2 homozygous knockout (UCP2−/−) mice have increased expression of IL-6 after listeria infection compared with wild-type controls [30].