Research ArticleSepsis

A Central Role for Free Heme in the Pathogenesis of Severe Sepsis

Science Translational Medicine  29 Sep 2010:
Vol. 2, Issue 51, pp. 51ra71
DOI: 10.1126/scitranslmed.3001118

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Low-grade polymicrobial infection induced by cecal ligation and puncture is lethal in heme oxygenase-1–deficient mice (Hmox1−/−), but not in wild-type (Hmox1+/+) mice. Here we demonstrate that the protective effect of this heme-catabolizing enzyme relies on its ability to prevent tissue damage caused by the circulating free heme released from hemoglobin during infection. Heme administration after low-grade infection in mice promoted tissue damage and severe sepsis. Free heme contributed to the pathogenesis of severe sepsis irrespective of pathogen load, revealing that it compromised host tolerance to infection. Development of lethal forms of severe sepsis after high-grade infection was associated with reduced serum concentrations of the heme sequestering protein hemopexin (HPX), whereas HPX administration after high-grade infection prevented tissue damage and lethality. Finally, the lethal outcome of septic shock in patients was also associated with reduced HPX serum concentrations. We propose that targeting free heme by HPX might be used therapeutically to treat severe sepsis.


  • * Present address: Universidade Federal do Rio de Janeiro Campus Macaé–Instituto Macaé de Metrologia e Tecnologia, Macaé, Rio de Janeiro 27930-560, Brazil.

  • Citation: R. Larsen, R. Gozzelino, V. Jeney, L. Tokaji, F. A. Bozza, A. M. Japiassú, D. Bonaparte, M. M. Cavalcante, Â. Chora, A. Ferreira, I. Marguti, S. Cardoso, N. Sepúlveda, A. Smith, M. P. Soares, A central role for free heme in the pathogenesis of severe sepsis. Sci. Transl. Med. 2, 51ra71 (2010).

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