Hemopexin: anti-inflammatory, pro-inflammatory, or both? W. W. Bakker 1 , B. N. Melgert and M. M. Faas Department of Pathology and Medical Biology, University Medical Center of Groningen, Groningen, The Netherlands 1. Correspondence: Department of Pathology and Medical Biology, University Medical Center of Groningen, Groningen, The Netherlands. E-mail: w.w.bakker@path.umcg.nl acute-phase reactants inflammation protease Dear Editor, The interesting article of Liang et al. [ 1 ] describes an anti-inflammatory property of Hx, showing down-regulation of LPS-induced secretion of TNF-α and IL-6 from murine bone marrow-derived or peritoneal macrophages in vitro. Commercially obtained human rHx appeared to exhibit the same activity [ 1 ] . In the Editorial of the same issue of this journal, by Mitchell P. Fink [ 2 ] , Hx is called: “…newest member of the anti-inflammatory club.” Indeed, the data of Liang et al. [ 1 ] provide convincing evidence for a novel property of Hx, as in text books or literature reviews up until now, Hx is known exclusively for its heme-scavenging properties, preventing heme-induced oxidant stress [ 3 , 4 ] . However, we have shown previously that purified plasma Hx as well as human rHx have protease activity that can be inhibited
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