Project

Using the L. amazonensis in vitro experimental infection model proposed in this PTR496 (October 2014 to October 2017), we have previously performed a comparative study of the transcriptomes of non-infected and infected macrophages harboring replicating amastigotes (24 hours post-infection). We already documented that intramacrophagic amastigotes were able to subvert their host cells by promoting the transcription of various macrophage genes beneficial for their intraphagosomal growth, such as those involved in sterol biosynthesis, phagosome acidification, and polyamine synthesis. Moreover, of particular interest for the present proposal, we also documented that L. amazonensis amastigotes were able to favor a counter-inflammatory environment by modulating the expression of pro- and anti-inflammatory genes, some of which are related to the inflammasome. Preliminary data are in favor of an absence of stimulation, even a down-regulation of the inflammasome in macrophages harboring replicating amastigotes at the gene and protein expression levels. This modulatory effect of intramacrophagic amastigotes is much stronger after 3 days of infection than after 1 day (initial Affymetrix study) as assessed by the qPCR analysis of key players involved in inflammasome activation. Thus, in the present proposal we will determine the gene expression profile of primary macrophages after 3 days of infection using RNAseq technology enabling a better understanding on how the amastigotes of L. amazonensis set up an anti-inflammatory niche within their host cells.