HIF-2α in resting macrophages tempers mitochondrial reactive oxygen species to selectively repress MARCO-dependent phagocytosis

Shirley Dehn, Matthew De Berge, Xin Yi Yeap, Laurent Yvan-Charvet, Deyu Fang, Holger K. Eltzschig, Stephen D. Miller, Edward B. Thorp*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Hypoxia-inducible factor (HIF)-α isoforms regulate key macrophage (MΦ) functions during ischemic inflammation. HIF-2α drives proinflammatory cytokine production; however, the requirements for HIF-2a during other key MF functions, including phagocytosis, are unknown. In contrast to HIF-1α, HIF-2α was not required for hypoxic phagocytic uptake. Surprisingly, basal HIF-2α levels under nonhypoxic conditions were necessary and sufficient to suppress phagocytosis. Screening approaches revealed selective induction of the scavenger receptor MARCO, which was required for enhanced engulfment. Chromatin immunopre-cipitation identified the antioxidant NRF2 as being directly responsible for inducing Marco. Concordantly, Hif-2α-/- MFs exhibited reduced antioxidant gene expression, and inhibition of mitochondrial reactive oxygen species suppressed Marco expression and phagocytic uptake. Ex vivo findings were recapitulated in vivo; the enhanced engulfment phenotype resulted in increased bacterial clearance and cytokine suppression. Importantly, natural induction of Hif-2α by IL-4 also suppressed MARCO-dependent phagocytosis. Thus, unlike most characterized prophagocytic regulators, HIF-2α can act as a phagocytic repressor. Interestingly, this occurs in resting MΦs through tempering of steady-state mitochondrial reactive oxygen species. In turn, HIF-2α promotes MΦ quiescence by blocking a MARCO bacterial-response pathway. IL-4 also drives HIF-2α suppression of MARCO, leading to compromised bacterial immunosurveillance in vivo.

Original languageEnglish (US)
Pages (from-to)3639-3649
Number of pages11
JournalJournal of Immunology
Volume197
Issue number9
DOIs
StatePublished - Nov 1 2016

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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