Browsing by Subject "Disease resistance"

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    IL-12 Mediates T-bet–Expressing Myeloid Cell–Dependent Host Resistance against Toxoplasma gondii
    (American Association of Immunologists, 2024) Schanz, Madison L.; Bitters, Abigail M.; Zadeii, Kamryn E.; Joulani, Dana; Chamberlain, Angela K.; López-Yglesias, Américo H.; Microbiology and Immunology, School of Medicine
    To defend against intracellular pathogens such as Toxoplasma gondii, the host generates a robust type 1 immune response. Specifically, host defense against T. gondii is defined by an IL-12-dependent IFN-γ response that is critical for host resistance. Previously, we demonstrated that host resistance is mediated by T-bet-dependent ILC-derived IFN-γ by maintaining IRF8+ conventional type 1 dendritic cells during parasitic infection. Therefore, we hypothesized that innate lymphoid cells are indispensable for host survival. Surprisingly, we observed that T-bet-deficient mice succumb to infection quicker than do mice lacking lymphocytes, suggesting an unknown T-bet-dependent-mediated host defense pathway. Analysis of parasite-mediated inflammatory myeloid cells revealed a novel subpopulation of T-bet+ myeloid cells (TMCs). Our results reveal that TMCs have the largest intracellular parasite burden compared with other professional phagocytes, suggesting they are associated with active killing of T. gondii. Mechanistically, we established that IL-12 is necessary for the induction of inflammatory TMCs during infection and these cells are linked to a role in host survival.
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    Systemic Acquired Resistance in Moss: Further Evidence for Conserved Defense Mechanisms in Plants
    (Public Library of Science, 2014-07-07) Winter, Peter S.; Bowman, Collin E.; Villani, Philip J.; Dolan, Thomas E.; Hauck, Nathanael R.; Medicine, School of Medicine
    Vascular plants possess multiple mechanisms for defending themselves against pathogens. One well-characterized defense mechanism is systemic acquired resistance (SAR). In SAR, a plant detects the presence of a pathogen and transmits a signal throughout the plant, inducing changes in the expression of various pathogenesis-related (PR) genes. Once SAR is established, the plant is capable of mounting rapid responses to subsequent pathogen attacks. SAR has been characterized in numerous angiosperm and gymnosperm species; however, despite several pieces of evidence suggesting SAR may also exist in non-vascular plants6-8, its presence in non-vascular plants has not been conclusively demonstrated, in part due to the lack of an appropriate culture system. Here, we describe and use a novel culture system to demonstrate that the moss species Amblystegium serpens does initiate a SAR-like reaction upon inoculation with Pythium irregulare, a common soil-borne oomycete. Infection of A. serpens gametophores by P. irregulare is characterized by localized cytoplasmic shrinkage within 34 h and chlorosis and necrosis within 7 d of inoculation. Within 24 h of a primary inoculation (induction), moss gametophores grown in culture became highly resistant to infection following subsequent inoculation (challenge) by the same pathogen. This increased resistance was a response to the pathogen itself and not to physical wounding. Treatment with β-1,3 glucan, a structural component of oomycete cell walls, was equally effective at triggering SAR. Our results demonstrate, for the first time, that this important defense mechanism exists in a non-vascular plant, and, together with previous studies, suggest that SAR arose prior to the divergence of vascular and non-vascular plants. In addition, this novel moss - pathogen culture system will be valuable for future characterization of the mechanism of SAR in moss, which is necessary for a better understanding of the evolutionary history of SAR in plants.