NK-, NKT- and CD8-Derived IFNγ Drives Myeloid Cell Activation and Erythrophagocytosis, Resulting in Trypanosomosis-Associated Acute Anemia.

TitleNK-, NKT- and CD8-Derived IFNγ Drives Myeloid Cell Activation and Erythrophagocytosis, Resulting in Trypanosomosis-Associated Acute Anemia.
Publication TypeJournal Article
Year of Publication2015
AuthorsCnops, J., De Trez C., Stijlemans B., Keirsse J., Kauffmann F., Barkhuizen M., Keeton R., Boon L., Brombacher F., and Magez S.
JournalPLoS Pathog
Volume11
Issue6
Paginatione1004964
Date Published2015 Jun
ISSN1553-7374
KeywordsAdoptive Transfer, Anemia, Animals, CD8-Positive T-Lymphocytes, Cell Separation, Disease Models, Animal, Erythrocytes, Female, Flow Cytometry, Interferon-gamma, Killer Cells, Natural, Mice, Mice, Inbred C57BL, Mice, Knockout, Myeloid Cells, Natural Killer T-Cells, Phagocytosis, Trypanosomiasis, African
Abstract

African trypanosomes are the causative agents of Human African Trypanosomosis (HAT/Sleeping Sickness) and Animal African Trypanosomosis (AAT/Nagana). A common hallmark of African trypanosome infections is inflammation. In murine trypanosomosis, the onset of inflammation occurs rapidly after infection and is manifested by an influx of myeloid cells in both liver and spleen, accompanied by a burst of serum pro-inflammatory cytokines. Within 48 hours after reaching peak parasitemia, acute anemia develops and the percentage of red blood cells drops by 50%. Using a newly developed in vivo erythrophagocytosis assay, we recently demonstrated that activated cells of the myeloid phagocytic system display enhanced erythrophagocytosis causing acute anemia. Here, we aimed to elucidate the mechanism and immune pathway behind this phenomenon in a murine model for trypanosomosis. Results indicate that IFNγ plays a crucial role in the recruitment and activation of erythrophagocytic myeloid cells, as mice lacking the IFNγ receptor were partially protected against trypanosomosis-associated inflammation and acute anemia. NK and NKT cells were the earliest source of IFNγ during T. b. brucei infection. Later in infection, CD8+ and to a lesser extent CD4+ T cells become the main IFNγ producers. Cell depletion and transfer experiments indicated that during infection the absence of NK, NKT and CD8+ T cells, but not CD4+ T cells, resulted in a reduced anemic phenotype similar to trypanosome infected IFNγR-/- mice. Collectively, this study shows that NK, NKT and CD8+ T cell-derived IFNγ is a critical mediator in trypanosomosis-associated pathology, driving enhanced erythrophagocytosis by myeloid phagocytic cells and the induction of acute inflammation-associated anemia.

DOI10.1371/journal.ppat.1004964
Alternate JournalPLoS Pathog.
PubMed ID26070118
PubMed Central IDPMC4466398
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