Article

The Role of Anorexia in Resistance and Tolerance to Infections in Drosophila

Department of Microbiology and Immunology, Stanford University, Stanford, California, USA.
PLoS Biology (Impact Factor: 11.77). 08/2009; 7(7):e1000150. DOI: 10.1371/journal.pbio.1000150
Source: PubMed

ABSTRACT Author Summary
Two routes to decreasing susceptibility to infection are resistance (the ability to clear pathogens) and tolerance (the ability to limit damage in response to pathogens). Anorexia induced by sickness puts animals into a diet-restricted state, a state that is generally believed to extend lifespan. We asked whether anorexia induced by sickness would alter the immune response. We measured the effects of diet restriction on both resistance and tolerance to two different infections in the fruit fly, Drosophila melanogaster. In one case we found that infection induced anorexia and the resulting diet restriction increased tolerance to this infection, thereby increasing survival of flies infected with this pathogen; however, this is not a universal effect. In a second case we found another pathogen that induced anorexia but here diet restriction lead to a reduction in resistance that collapsed the immune response and caused the fly to die faster. The relationship between diet restriction and immunity is complicated and must be evaluated on a pathogen-by-pathogen basis.

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    • "Although the response of GA cockroaches is driven by gustatory deterrence and is therefore not directly toxin - induced , the feeding response to glucose - contain - ing diets by GA cockroaches is highly comparable to the feeding response observed in animals that are infected with a toxin - producing pathogen . Infected ani - mals typically reduce consumption rate ( Exton , 1997 ; Ayres & Schneider , 2009 ; Adamo et al . , 2010 ) . "
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    • "This phenomenon is phylogenetically conserved, which perhaps points to a fundamental function, and a variety of adaptive benefits has been proposed (Exton 1997). Experiments in insects suggest anorexia can enhance survival during pathogen attack (Ayres & Schneider 2009) and may function to mediate conflicts between processing food and immune activity (Adamo et al. 2010). One mechanistic factor shaping these immune-induced metabolic shifts is that some immune system molecular pathways have pleiotropic roles in other physiological processes . "
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