Nrf2, a PPARγ alternative pathway to promote CD36 expression on inflammatory macrophages: implication for malaria

PLoS Pathog. 2011 Sep;7(9):e1002254. doi: 10.1371/journal.ppat.1002254. Epub 2011 Sep 15.

Abstract

CD36 is the major receptor mediating nonopsonic phagocytosis of Plasmodium falciparum-parasitized erythrocytes by macrophages. Its expression on macrophages is mainly controlled by the nuclear receptor PPARγ. Here, we demonstrate that inflammatory processes negatively regulate CD36 expression on human and murine macrophages, and hence decrease Plasmodium clearance directly favoring the worsening of malaria infection. This CD36 downregulation in inflammatory conditions is associated with a failure in the expression and activation of PPARγ. Interestingly, using siRNA mediating knock down of Nrf2 in macrophages or Nrf2- and PPARγ-deficient macrophages, we establish that in inflammatory conditions, the Nrf2 transcription factor controls CD36 expression independently of PPARγ. In these conditions, Nrf2 activators, but not PPARγ ligands, enhance CD36 expression and CD36-mediated Plasmodium phagocytosis. These results were confirmed in human macrophages and in vivo where only Nrf2 activators improve the outcome of severe malaria. Collectively, this report highlights that the Nrf2 transcription factor could be an alternative target to PPARγ in the control of severe malaria through parasite clearance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD36 Antigens / biosynthesis*
  • Down-Regulation
  • Erythrocytes / parasitology
  • Female
  • Humans
  • Macrophages / immunology*
  • Macrophages / metabolism
  • Macrophages / parasitology
  • Malaria, Falciparum / immunology*
  • Malaria, Falciparum / parasitology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • NF-E2-Related Factor 2 / genetics
  • NF-E2-Related Factor 2 / metabolism*
  • PPAR gamma / genetics
  • PPAR gamma / metabolism
  • Phagocytosis*
  • Plasmodium falciparum / immunology*
  • Plasmodium falciparum / metabolism

Substances

  • CD36 Antigens
  • NF-E2-Related Factor 2
  • NFE2L2 protein, human
  • Nfe2l2 protein, mouse
  • PPAR gamma