Kwok, S. | Search bioRxiv

bioRxiv2020

ILC1-derived IFN-gamma mediates cDC1-dependent host resistance against Toxoplasma gondii

Host resistance against intracellular pathogens requires a rapid IFN-{gamma} mediated immune response. We reveal that T-bet-dependent production of IFN-{gamma} is essential for the maintenance of inflammatory DCs at the site of infection with a common protozoan parasite, Toxoplasma gondii. A detailed analysis of the cellular sources for T-bet-dependent IFN-{gamma} identified that ILC1s, but not NK or TH1 cells, were involved in the regulation of inflammatory DCs via IFN-{gamma}. Mechanistically, we established that T-bet dependent ILC1-derived IFN-{gamma} is critical for the induction of IRF8, an essential transcription factor for cDC1s. Failure to upregulate IRF8 in DCs resulted in acute susceptibility to T. gondii infection. Our data identifies that ILC1-derived IFN-{gamma} is indispensable for host resistance against intracellular infection via maintaining IRF8+ inflammatory DCs at the site of infection. Author SummaryMounting a robust type I innate immune response is essential for resistance against numerous intracellular pathogens. The type I immune response is characterized by the production of IFN-{gamma}, a central cytokine required for multiple non-redundant effector functions against bacterial, viral, and parasitic pathogens. Previous work has shown that group 1 innate lymphocyte cells (ILC1s) together with NK and CD4+ T cells play an indispensable IFN-{gamma} mediated protective role against Toxoplasma gondii infection; yet, the pathway of how IFN-{gamma} produced by ILC1s defend against T. gondii remains unknown. In this work we identified that early production of IFN-{gamma} by ILC1 is essential for maintaining dendritic cells (DCs) during infection. Mechanistically, we reveal that ILC1-derived IFN-{gamma} is indispensable for inducing the transcription factor IRF8 that is critical for sustaining inflammatory DCs. Finally, we demonstrate that IRF8+ DCs are critical for parasite elimination.

immunology↗

bioRxiv2019

Investigating mechanisms of polarized light sensitivity in the small white butterfly Pieris rapae

There is an ever increasing number of arthropod taxa shown to have polarization sensitivity throughout their compound eyes. However, the mechanisms underlying arthropod perception of polarized reflections from objects such as plants are not well understood. The small white butterfly, Pieris rapae, has been demonstrated to exploit foliar polarized reflections, specifically the degree of linear polarization (DoLP), to recognize host plants. The well-described visual system of P. rapae includes several photoreceptor types (red, green, blue) that are sensitive to polarized light. Yet, the mechanism underlying the behavioral responses of P. rapae to stimuli with different DoLPs remains unknown. To investigate potential mechanisms, we designed several two-choice behavioral bioassays, displaying plant images on paired LCD monitors which allowed for independent control of polarization, color and intensity. We found that shifts in image intensity had a similar effect on P. rapae preferences for stimuli dissimilar in DoLP and dissimilar in color, suggesting DoLP differences are perceived as color. When a DoLP choice was offered between plant images manipulated in a manner to minimizing the response of blue, red, or blue and red photoreceptors, P. rapae shifted its preference for DoLP, suggesting a role for red, green and blue polarization-sensitive photoreceptors. Modeling of P. rapae photoreceptor responses to test stimuli suggests that differential DoLP is not perceived solely as a color difference. Our combined results suggest that P. rapae females process and interpret polarization reflections in a way different from that described for other polarization-sensitive taxa.

animal behavior and cognition↗