Type I interferons promote fatal immunopathology by regulating inflammatory monocytes and neutrophils during Candida infections

PLoS Pathog. 2012;8(7):e1002811. doi: 10.1371/journal.ppat.1002811. Epub 2012 Jul 26.

Abstract

Invasive fungal infections by Candida albicans (Ca) are a frequent cause of lethal sepsis in intensive care unit patients. While a contribution of type I interferons (IFNs-I) in fungal sepsis remains unknown, these immunostimulatory cytokines mediate the lethal effects of endotoxemia and bacterial sepsis. Using a mouse model lacking a functional IFN-I receptor (Ifnar1⁻/⁻), we demonstrate a remarkable protection against invasive Ca infections. We discover a mechanism whereby IFN-I signaling controls the recruitment of inflammatory myeloid cells, including Ly6C(hi) monocytes and neutrophils, to infected kidneys by driving expression of the chemokines CCL2 and KC. Within kidneys, monocytes differentiate into inflammatory DCs but fail to functionally mature in Ifnar1⁻/⁻ mice, as demonstrated by the impaired upregulation of the key activation markers PDCA1 and iNOS. The increased activity of inflammatory monocytes and neutrophils results in hyper-inflammation and lethal kidney pathology. Pharmacological diminution of monocytes and neutrophils by treating mice with pioglitazone, a synthetic agonist of the nuclear receptor peroxisome proliferator-activated receptor-γ (PPAR-γ), strongly reduces renal immunopathology during Ca infection and improves mouse survival. Taken together, our data connect for the first time the sepsis-promoting functions of IFNs-I to the CCL2-mediated recruitment and the activation of inflammatory monocytes/DCs with high host-destructing potency. Moreover, our data demonstrate a therapeutic relevance of PPAR-γ agonists for microbial infectious diseases where inflammatory myeloid cells may contribute to fatal tissue damage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD / biosynthesis
  • Antigens, Ly / biosynthesis
  • Candida albicans / immunology*
  • Candidemia / mortality
  • Candidiasis / immunology*
  • Candidiasis / pathology
  • Chemokine CCL2 / biosynthesis
  • Chemokine CXCL1 / biosynthesis
  • Dendritic Cells / immunology
  • Inflammation / drug therapy
  • Inflammation / immunology
  • Interferon Type I / metabolism*
  • Kidney / immunology
  • Kidney / microbiology
  • Male
  • Membrane Glycoproteins / biosynthesis
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Monocytes / drug effects
  • Monocytes / immunology*
  • Neutrophils / drug effects
  • Neutrophils / immunology*
  • Nitric Oxide Synthase Type II / biosynthesis
  • PPAR gamma / agonists
  • Pioglitazone
  • Receptors, Interferon / deficiency
  • Receptors, Interferon / genetics
  • Signal Transduction / genetics
  • Thiazolidinediones / pharmacology
  • Thiazolidinediones / therapeutic use

Substances

  • Antigens, CD
  • Antigens, Ly
  • BST2 protein, mouse
  • Ccl2 protein, mouse
  • Chemokine CCL2
  • Chemokine CXCL1
  • Cxcl1 protein, mouse
  • Interferon Type I
  • Ly-6C antigen, mouse
  • Membrane Glycoproteins
  • PPAR gamma
  • Receptors, Interferon
  • Thiazolidinediones
  • Nitric Oxide Synthase Type II
  • Pioglitazone