Nutritional factors can have profound influence on immune defense, but the mechanisms linking dietary nutrition to immunity are poorly understood. Work performed under the proposed project will establish the relationship between nutrition and defense from physiological and genetic perspectives, and will ultimately identify genes contributing to individual-specific alteration in immunity due to diet. The project will make use of the model insect Drosophila melanogaster, which has metabolic and immune systems that are highly conserved with homologous systems in vertebrates.
In Aim 1 of the project, D. melanogaster provided with diets of varying nutritional composition will be evaluated for resistance to bacterial infection (measured as immune system activity and suppression of bacterial proliferation) and tolerance of infection (measured as the ability to sustain health while infected). The experimental diets to be evaluated will vary in protein, sugar and fat levels.
Aim 2 of the project will test the hypothesis that specific immune and metabolic signaling pathways are linked during infection, such that activation of the immune system causes altered metabolism and energetic utilization. The IMD (immune system), JNK (stress response), and insulin-like (metabolism) signaling pathways will be genetically disrupted to test for cross-communication between processes during the early stages of an infection.
Aim 3 of the project will conceptually link the first two Aims in a study of naturally occurring variation. It is known that individuals in natural populations are genetically variable for both immune-related and metabolic traits. Experiments to be performed under Aim 3 will determine the degree to which resistance and tolerance phenotypes are determined by genotype-specific effects of diet (termed genotype-by-environment interaction). These interactions form the conceptual basis of personalized medicine, and understanding them will be crucial for advanced clinical therapeutics. Analysis of known polymorphisms and unbiased genome-wide association mapping will be employed to identify genes responsible for genotype-specific immunological alteration with diet. The data collected under all three Aims will provide novel and broadly comprehensive understanding of dietary effects on defense quality, with critical implications for clinical and evolutionary biology.

Public Health Relevance

It is intuitively appreciated that dietary nutrition can influence resistance to infection, but the mechanisms connecting nutrition to defense are poorly understood. The proposed study will evaluate the impact of dietary nutrients on immune defense, will determine the genetic mechanisms linking nutrition and defense, and will identify genes contributing to individual-specific alterations in immunity attributable to diet. The work will contribute to understanding disease resistance and susceptibility in evolutionary and clinically relevant contexts.

National Institute of Health (NIH)
Research Project (R01)
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Genetic Variation and Evolution Study Section (GVE)
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Leitner, Wolfgang W
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Cornell University
Earth Sciences/Resources
United States
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Howick, Virginia M; Lazzaro, Brian P (2014) Genotype and diet shape resistance and tolerance across distinct phases of bacterial infection. BMC Evol Biol 14:56
Chambers, Moria C; Jacobson, Eliana; Khalil, Sarah et al. (2014) Thorax injury lowers resistance to infection in Drosophila melanogaster. Infect Immun 82:4380-9
Short, Sarah M; Lazzaro, Brian P (2013) Reproductive status alters transcriptomic response to infection in female Drosophila melanogaster. G3 (Bethesda) 3:827-40
Del Campo, Marta L; Halitschke, Rayko; Short, Sarah M et al. (2013) Dietary plant phenolic improves survival of bacterial infection in Manduca sexta caterpillars. Entomol Exp Appl 146:321-331
Galac, Madeline R; Lazzaro, Brian P (2011) Comparative pathology of bacteria in the genus Providencia to a natural host, Drosophila melanogaster. Microbes Infect 13:673-83
Short, Sarah M; Lazzaro, Brian P (2010) Female and male genetic contributions to post-mating immune defence in female Drosophila melanogaster. Proc Biol Sci 277:3649-57
Fellous, Simon; Lazzaro, Brian P (2010) Larval food quality affects adult (but not larval) immune gene expression independent of effects on general condition. Mol Ecol 19:1462-8