Impact of bat hibernation on metabolism and immunity to infection - PROJECT SUMMARY/ABSTRACT We propose to study the link between bat hibernation, metabolism and immunity in the setting of infection. Bats are uniquely vulnerable to Pseudogymnoascus destructans (Pd), a fungal invader that infects bat skin during hibernation. The fungal epidemic of white nose syndrome has killed millions of North American hibernating bats, highlighting the need to understand how temperature impacts immunometabolism and resistance to infection. Mechanistic links that underpin this relationship in bat innate immune cells in skin represent a knowledge gap. Keratinocytes sense skin infection and secrete cytokines to recruit other immune cells. Neutrophils detect the signals and migrate into the tissue, releasing reactive oxygen species and extracellular traps to phagocytose and kill invaders. Keratinocyte and neutrophil functions demand energy and metabolic rewiring to sustain energy demand. In preliminary data, we found that hibernation alters pathways regulated by PI3K/mTOR, HIF-1a, “temperature-sensing” TRPV3 and EGFR associated with metabolic rewiring. We hypothesize that hibernation temperatures impact the metabolism and function of bat keratinocytes and neutrophils, and that mTOR, HIF-1α, TRPV3 and EGFR underpin the interconnection between temperature, metabolism and immunity. We will test this hypothesis in a novel bat hibernation model and 3D organotypic platform in the setting of infection with Pd. Aim 1 defines how temperature affects keratinocyte metabolism & function. We will use our hibernation model to test how temperature changes affect keratinocytes: barrier integrity; redox potential: mitochondrial fitness; glycolysis and oxidative phosphorylation. We will also test how temperature changes affect keratinocyte immune functions such as alarmin response to pathogen associated molecular patterns (PAMP), particle uptake, and production of antimicrobial effectors e.g. ROS. We will use RNA silencing and pharmacological inhibitors to establish mechanistic links between metabolic regulators noted above and keratinocyte immune function. Aim 2 defines how temperature affects keratinocyte & neutrophil metabolism & response to Pd infection. We will use a 3-D organotypic model combined with non-destructive and real-time imaging to define how temperature change affects metabolism and response to Pd. We will test keratinocyte function as outlined above together with neutrophil function including migration, extravasation, phagocytosis of Pd, NETosis, and Pd killing. We will use RNA silencing and pharmacological inhibitors/agonists targeting metabolic pathways in keratinocytes to test how they affect, or rescue, keratinocyte and neutrophil immune response to Pd and clearance of infection. Our work will offer new insight on how temperatures during hibernation uniquely affects bat immunity to infection.
