Mixed-Up Microflora

Science Signaling  12 Feb 2008:
Vol. 1, Issue 6, pp. ec58
DOI: 10.1126/stke.16ec58

The relationship between an animal host and the complex mixture of microbes it carries in its gut is a delicate one, and the exact role the host immune system plays in maintaining commensal homeostasis remains unclear. Ryu et al. (see the Perspective by Silverman and Paquette) examined the expression of antimicrobial proteins in the gut of the fruit fly, Drosophila melanogaster. Although the key immune transcriptional regulator nuclear factor κB (NF-κB) was chronically activated in the flies by indigenous gut microflora, only a subset of NF-κB-regulated antimicrobial genes was actually expressed because of transcriptional repression exerted by the intestinal homeobox gene Caudal. Disruption of Caudal expression resulted in the expression of a different subset of antimicrobial peptides, as well as a dramatic change in the composition of the intestinal microflora that led to the apoptosis of intestinal epithelial cells and loss of host viability.

J.-H. Ryu, S.-H. Kim, H.-Y. Lee, J. Y. Bai, Y.-D. Nam, J.-W. Bae, D. G. Lee, S. C. Shin, E.-M. Ha, W.-J. Lee, Innate immune homeostasis by the homeobox gene Caudal and commensal-gut mutualism in Drosophila. Science 319, 777-782 (2008). [Abstract] [Full Text]

N. Silverman, N. Paquette, The right resident bugs. Science 319, 734-735 (2008). [Abstract] [Full Text]