Nuclear factor-κB mediated lipopolysaccharide-induced mRNA expression of hepcidin in human peripheral blood leukocytes

Abstract

Hepcidin is a known key modulator of iron homeostasis and an innate immune molecule secreted by the liver. The transcriptional mechanism of hepcidin in hepatocytes during inflammation is mediated via the IL-6/STAT3 pathway. Recently, hepcidin demonstrated an anti-inflammatory function in endotoxic mice, and a TLR4-dependent inducible expression of hepcidin was detected in myeloid cells. In this study, we explored the expression and signaling mechanism regulating hepcidin mRNA expression in peripheral blood leukocytes. The mRNA levels of hepcidin in peripheral blood leukocytes from patients with severe sepsis (n = 14) was significantly higher than those in healthy controls (n = 16;0.286 ± 0.065 vs 0.068 ± 0.025; P < 0.05). Ex vivo studies found hepcidin mRNA can be highly induced by challenge of 100 ng/ml LPS or 20 ng/ml TNF-α in peripheral blood leukocytes rather than IL-6, IL-1 and IFN-γ. Anti-TNF-α antibody significantly decreased the levels of hepcidin mRNA induced by LPS. Inhibitor of nuclear factor (NF)-κB rather than that of STAT3 completely abolished the inducibility of hepcidin mRNA in PBMCs and neutrophils. These results indicate that hepcidin mRNA expression in peripheral blood leukocytes induced by LPS depends on NF-κB, and TNF-α may be a key mediator in this procedure.