Insect Models of Immunosenescence

Abstract

For the past few decades invertebrates have been used extensively as models for understanding the general process of senescence (see reviews by Partridge and Gems 2002 ; Grotewiel et al. 2005 ; Keller and Jemielity 2006 ; Houthoofd and Vanfleteren 2007 ) and since the 1920’s as models for understanding the genes, signaling pathways and cellular processes involved in innate immunity (Brey 1998 ). These two fields of study have begun to merge as invertebrate models, chiefly terrestrial insects, are increasingly being used to understand both the causes and consequences of age-related changes in immunocompetence. Invertebrates are ideally suited for such studies as they generally have short generation times, short life spans and can be raised in large numbers which improves statistical power for detecting the effects of genetic and environmental influences on functional measures of the immune response. In addition, recently completed genome sequences of invertebrates (e.g., Caenorhabditis elegans : C. elegans Sequencing Consortium 1998 ; Drosophila melanogaster : Adams et al. 2000 ; Anopheles gambiae : Holt et al. 2002 : Bombyx mori : Xia et al. 2004 ) reveal that many of the genes regulating the innate immune response have homologous genes in vertebrates. Molecular genetic studies have also revealed extensive homology between invertebrates and vertebrates in the signaling pathways that are activated to fight infection (Hoffmann and Reichhart 2002 ). Thus, the use of invertebrate models is likely to contribute a great deal to our understanding of the genetic influences on immunosenescence in a wide range of organisms, including humans.