Ferritin functions as a proinflammatory cytokine via iron-independent protein kinase C zeta/nuclear factor kappaB - Regulated signaling in rat hepatic stellate cells

Circulating ferritin levels reflect body iron stores and are elevated with inflammation in chronic liver injury. H-ferritin exhibits a number of extrahepatic immunomodulatory properties, although its role in hepatic inflammation and fibrogenesis is unknown. Hepatic stellate cells respond to liver injury through production of proinflammatory mediators that drive fibrogenesis. A specific receptor for ferritin has been demonstrated on activated hepatic stellate cells, although its identity and its role in stellate cell activation is unclear. We propose that ferritin acts as a cytokine regulating proinflammatory function via nuclear factor kappaB (NF-?B)-regulated signaling in hepatic stellate cell biology. Hepatic stellate cells were treated with tissue ferritin and iron-free apoferritin, recombinant H-ferritins and L-ferritins, to assess the role of ferritin versus ferritin-bound iron in the production of proinflammatory mediators of fibrogenesis, and to determine whether signaling pathways act via a proposed H-ferritin endocytosis receptor, T cell immunoglobulin-domain and mucin-domain 2 (Tim-2).