Ectopic activation of the immune response in the larval airway epithelium

The unsurpassed simplicity of the fruitfly’s airway epithelium, that is made of homogenous epithelial cells only, favours its use as a model to study general features and response characteristics of airway epithelia in general. All epithelial cells are able to launch an immune response as characterized by the expression of antimicrobial peptide genes. Infection induces a complex change in the expression profile of these epithelial cells. Outstanding are a priming of the immune system and the launch of a survival program, presumably to counteract infection induced apoptotic signals, which comprises the concurrent expression of known longevity genes such as dFoxo, and dThor. In regions of the airway epithelium with strong immune reactions, a complex remodelling of the airways can be observed, which is characterized by metaplasia and presumably also by hyperplasia of the affected epithelial cells. At the transcriptional level, this reorganization of the airway epithelium is mirrored by a recapitulation of genetic programs that are characteristic for early phases of airway development. Taken together, the response characteristics of the fly’s airway epithelium towards infections discloses features that are known from inflammatory diseases of the human lung, thus opening the opportunity to study fundamental aspects of these diseases in the fly. Keywords: Ectopic activation of IMD, larval airways, third instar larvae, Gal4/UAS-system, two-colour microarrays Ectopic activiation of the Immune deficiency pathway in the larval airway epithelium using the Gal4/UAS-system of Brand and Perrimon. The activation was induced by the overexpression of the pattern recognition receptor PGRP-LE using a driver line which was specific for the tracheal system of the larvae. In general four replicates were performed including dye-swaps in two-colour arrays. A table of significantly-regulated genes from the SAM-output and GeneTraffic-output has been linked as a supplementary file at the foot of this record.