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J Immunol. 2018 Feb 15;200(4):1443-1456. doi: 10.4049/jimmunol.1700782. Epub 2018 Jan 10.

IFN Regulatory Factor 3 Balances Th1 and T Follicular Helper Immunity during Nonlethal Blood-Stage Plasmodium Infection.

Author information

1
Malaria Immunology Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia.
2
Ph.D. Program, School of Medicine, University of Queensland, Herston, Queensland 4006, Australia.
3
Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria 8008, Australia.
4
Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4072, Australia.
5
Australian Infectious Diseases Research Centre, University of Queensland, St. Lucia, Queensland 4072, Australia.
6
Inflammation Biology Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia.
7
Gordon and Jesse Gilmour Leukaemia Research Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia.
8
Bone Marrow Transplantation Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia; and.
9
Immunology and Infection Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia.
10
Malaria Immunology Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia; Ashraful.haque@qimrberghofer.edu.au.

Abstract

Differentiation of CD4+ Th cells is critical for immunity to malaria. Several innate immune signaling pathways have been implicated in the detection of blood-stage Plasmodium parasites, yet their influence over Th cell immunity remains unclear. In this study, we used Plasmodium-reactive TCR transgenic CD4+ T cells, termed PbTII cells, during nonlethal P. chabaudi chabaudi AS and P. yoelii 17XNL infection in mice, to examine Th cell development in vivo. We found no role for caspase1/11, stimulator of IFN genes, or mitochondrial antiviral-signaling protein, and only modest roles for MyD88 and TRIF-dependent signaling in controlling PbTII cell expansion. In contrast, IFN regulatory factor 3 (IRF3) was important for supporting PbTII expansion, promoting Th1 over T follicular helper (Tfh) differentiation, and controlling parasites during the first week of infection. IRF3 was not required for early priming by conventional dendritic cells, but was essential for promoting CXCL9 and MHC class II expression by inflammatory monocytes that supported PbTII responses in the spleen. Thereafter, IRF3-deficiency boosted Tfh responses, germinal center B cell and memory B cell development, parasite-specific Ab production, and resolution of infection. We also noted a B cell-intrinsic role for IRF3 in regulating humoral immune responses. Thus, we revealed roles for IRF3 in balancing Th1- and Tfh-dependent immunity during nonlethal infection with blood-stage Plasmodium parasites.

PMID:
29321276
DOI:
10.4049/jimmunol.1700782

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