STAT3 signaling within hepatocytes is required for anemia of inflammation in vivo.

Background: Anemia of inflammation, commonly observed in patients with chronic diseases, is associated with decreased serum iron. Hepcidin, mainly produced by hepatocytes in a STAT3- and/or SMAD-dependent manner, is involved in iron homeostasis. What remains to be established is whether or not the hepatic IL-6/STAT3 signal has a role in anemia of inflammation in vivo.

Methods: Turpentine oil was subcutaneously injected into wild-type mice or hepatocyte-specific STAT3-deficient mice (L-STAT3KO) to induce inflammation.

Results: Turpentine injection increased serum IL-6 levels. It activated liver STAT3 in wild-type mice, but not in L-STAT3KO mice. In chronic inflammation, wild-type mice showed decreased serum iron levels and anemia with up-regulation of hepcidin levels in the liver. In contrast, L-STAT3KO mice showed no increase in hepatic hepcidin levels or anemia.

Conclusions: Liver STAT3 is critically involved in the development of anemia of inflammation via the expression of hepcidin. The liver regulates anemia of inflammation through STAT3 signaling.