Direct In Vivo Manipulation and Imaging of Calcium Transients in Neutrophils Identify a Critical Role for Leading-Edge Calcium Flux.
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2015-12-15
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Calcium signaling has long been associated with key events of immunity, including chemotaxis, phagocytosis, and activation. However, imaging and manipulation of calcium flux in motile immune cells in live animals remain challenging. Using light-sheet microscopy for in vivo calcium imaging in zebrafish, we observe characteristic patterns of calcium flux triggered by distinct events, including phagocytosis of pathogenic bacteria and migration of neutrophils toward inflammatory stimuli. In contrast to findings from ex vivo studies, we observe enriched calcium influx at the leading edge of migrating neutrophils. To directly manipulate calcium dynamics in vivo, we have developed transgenic lines with cell-specific expression of the mammalian TRPV1 channel, enabling ligand-gated, reversible, and spatiotemporal control of calcium influx. We find that controlled calcium influx can function to help define the neutrophil's leading edge. Cell-specific TRPV1 expression may have broad utility for precise control of calcium dynamics in other immune cell types and organisms.
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Tobin, DM (2015). Direct In Vivo Manipulation and Imaging of Calcium Transients in Neutrophils Identify a Critical Role for Leading-Edge Calcium Flux. Cell Rep, 13(10). pp. 2107–2117. 10.1016/j.celrep.2015.11.010 Retrieved from https://hdl.handle.net/10161/12637.
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Scholars@Duke
David M. Tobin
Tuberculosis: Mycobacterial Pathogenesis and Host Susceptibility
Tuberculosis kills 1.5 million people annually. Our laboratory aims to understand the intricate interplay between mycobacteria and their hosts using a combination of model organism genetics, human genetics, pharmacology and high-resolution microscopy. By identifying key pathways utilized by the infecting bacteria and the host innate immune system, we hope to discover new therapeutic targets and interventions to combat this enduringly destructive disease.
Using a Mycobacterium/zebrafish model, we have identified new host susceptibility loci for tuberculosis. Zebrafish are natural hosts to Mycobacterium marinum, the closest relative of the Mycobacterium tuberculosis complex. Because zebrafish embryos and larvae are optically transparent, we are able to visualize the complex details of mycobacterial pathogenesis in whole, live animals. The facile genetics of the zebrafish allow us to map and positionally clone affected host susceptibility genes. In addition, zebrafish larvae are remarkably permeable to small molecules, providing a platform for whole-animal pharmacological manipulation of specific host immune responses.
We have identified novel pathways that modulate susceptibility to tuberculosis. We have shown that genes identified in the zebrafish model are also important in human tuberculosis. We find robust associations of human variants in a specific eicosanoid pathway with susceptibility to both tuberculosis and leprosy.
We have active collaborations in both Vietnam and Guatemala. In Guatemala, we are working with the Clínica Familiar Luis Angel García and the Asociación de Salud Integral to support projects involving HIV-infected patients and to understand the dynamics of TB transmission in Central America.
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