This blog post is provided by Fleur Ponton, Senior Lecturer in Insect Biology at  Macquarie University in Sydney, Australia. Fleur and her team are investigating the relationship between nutrition, immunology and gut microbiota, primarily using flies as model species, this blog discusses her recent paper in the journal.

Infection and nutrition are intimately linked. Nutrients in the diet play a fundamental role in sustaining an optimal immune response, such that both deficient and excessive intakes can have negative consequences on the immune status and susceptibility to a variety of pathogens. In humans, malnutrition affects immunity and infections, with under-nutrition being the primary cause of immunodeficiency worldwide, and over-nutrition and its associated metabolic disorders impairing the immune function and increasing susceptibility to infectious disease. The interactions involving nutrition and immunity and how the host deals with infectious agents are, therefore, critical aspects of human and animal health. Despite the importance of these interactions, the challenge remains to capture the complexity of the relationship between nutrition and immunity.

Here we performed a detailed investigation of the dietary modulation of innate immunity and resistance to bacterial infection in an age-dependent manner. The effects of nutrition were measured through a geometric manipulation of the dietary protein and carbohydrate balance using Drosophila melanogaster as a system model. Our observations unveiled nutritional regulations of innate immunity expression and resistance to bacterial infections, furthermore it shows that animals can self-medicate by shifting their diet choice. Our work reinforces the idea that self-medication can happen through modulating macronutrient (carbohydrates and protein) selection to stimulate the immune response and potentially compensate for the negative effects of the infection.

This work establishes new avenues for research on human and animal health. The percentage of obesity has been constantly increasing worldwide. Obesity increases the risk of diseases and health problems. This research helps to understand how both excessive and deficient intakes of nutrients affect the immune status and susceptibility to pathogens, but also the capability of animals to self-select a diet that will promote their survival after infection. The interactions involving nutrition and immunity, and how the host deals with infectious agents are critical aspects of animal health.

The research was through a collaboration between the University of Sydney (Charles Perkins Centre) and Macquarie University.

Read the full paper

Ponton, F. , Morimoto, J. , Robinson, K. , Kumar, S. S., Cotter, S. , Wilson, K. and Simpson, S. J. (2019), Macronutrients modulate survival to infection and immunity in Drosophila. J Anim Ecol. https://doi.org/10.1111/1365-2656.13126