title: Comparative Analysis of Conventional Natural Killer Cell Responses to Acute Infection withToxoplasma gondiiStrains of Different Virulence.
abstract: Conventional natural killer (cNK) cells, members of group 1 innate lymphoid cells, are a diverse cell subpopulation based on surface receptor expression, maturation, and functional potential. cNK cells are critical for early immunity toToxoplasma gondii viaIFNγ production. Acute cNK cell responses to infection with different strains ofT. gondiihave not yet been characterized in detail. Here, we comprehensively performed this analysis with Type I virulent RH, Type II avirulent ME49, and fully attenuated Type Icps1-1strains. In response to these three parasite strains, murine cNK cells produce IFNγ and become cytotoxic and polyfunctional (IFNγ+CD107a+) at the site of infection. In contrast to virulent RH and avirulent ME49T. gondiistrains, attenuatedcps1-1induced only local cNK cell responses. Infections with RH and ME49 parasites significantly decreased cNK cell frequency and numbers in spleen 5 days post infection compared withcps1-1parasites. cNK cell subsets expressing activating receptors Ly49H, Ly49D, and NKG2D and inhibitory receptors Ly49I and CD94/NKG2A were similar when compared between the strains and at 5 days post infection. cNK cells were not proliferating (Ki67-) 5 days post infection with any of the strains. cNK cell maturation as measured by CD27, CD11b, and KLRG1 was affected after infection with different parasite strains. RH and ME49 infection significantly reduced mature cNK cell frequency and increased immature cNK cell populations compared withcps1-1infection. Interestingly, KLRG1 was highly expressed on immature cNK cells after RH infection. After RH and ME49 infections, CD69+ cNK cells in spleen were present at higher frequency than aftercps1-1infection, which may correlate with loss of the mature cNK cell population. Cytokine multiplex analysis indicated cNK cell responses correlated with peritoneal exudate cell, spleen, and serum proinflammatory cytokine levels, including IL-12. qPCR analysis of parasite-specific B1 gene revealed that parasite burdens may affect cNK cell responses. This study demonstrates infection with RH and ME49 parasites impacts cNK cell maturation during acuteT. gondiiinfection. Different cNK cell responses could impact early immunity and susceptibility to these strains.
authors.affiliation: Department of Molecular Biology, University of Wyoming , Laramie, WY , USA.
authors.forename: Daria L
authors.initials: DL
authors.lastname: Ivanova
authors.affiliation: Department of Molecular Biology, University of Wyoming , Laramie, WY , USA.
authors.forename: Rida
authors.initials: R
authors.lastname: Fatima
authors.affiliation: Department of Molecular Biology, University of Wyoming , Laramie, WY , USA.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Gigley
keywords: Toxoplasma gondii; cytokines; natural killer cells; toxoplasmosis; virulence