The Drosophila Immune Deficiency Pathway Modulates Enteroendocrine Function and Host Metabolism

Publication date: Available online 21 June 2018
Source:Cell Metabolism
Author(s): Layla Kamareddine, William P. Robins, Cristin D. Berkey, John J. Mekalanos, Paula I. Watnick
Enteroendocrine cells (EEs) are interspersed between enterocytes and stem cells in the Drosophila intestinal epithelium. Like enterocytes, EEs express components of the immune deficiency (IMD) innate immune pathway, which activates transcription of genes encoding antimicrobial peptides. The discovery of large lipid droplets in intestines of IMD pathway mutants prompted us to investigate the role of the IMD pathway in the host metabolic response to its intestinal microbiota. Here we provide evidence that the short-chain fatty acid acetate is a microbial metabolic signal that activates signaling through the enteroendocrine IMD pathway in a PGRP-LC-dependent manner. This, in turn, increases transcription of the gene encoding the endocrine peptide Tachykinin (Tk), which is essential for timely larval development and optimal lipid metabolism and insulin signaling. Our findings suggest innate immune pathways not only provide the first line of defense against infection but also afford the intestinal microbiota control over host development and metabolism.

Graphical abstract

Teaser

Here Kamareddine et al. show that an innate immune pathway in enteroendocrine cells of the Drosophila melanogaster intestine is activated by the intestinal microbiota and the microbial metabolite acetate. Activation of this pathway increases expression of the endocrine peptide tachykinin to promote host metabolic homeostasis.


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