Transcriptional signatures of BALB/c mouse macrophages housing multiplying Leishmania amazonensis amastigotes

In mammals, resident dermal macrophages (Ms) are subverted by Leishmania (L.) amazonensis amastigotes as host cells permissive for parasite multiplication. These Leishmania are living within a communal parasitophorous vacuole (PV) and are expected to trigger unique M transcriptional signatures. We performed a transcription profiling of mouse Ms harboring amastigotes to get insights into their reprogramming as host cells for parasite multiplication. BALB/c mouse bone marrow-derived Ms were either loaded or not with four amastigotes on average. Twenty four hours later, when amastigotes multiply, total RNA from M cultures was prepared, amplified and hybridized onto Affymetrix Mouse430_2 GeneChips. The outcome recorded a total of 1,248 probe-sets showing significant differential expression. Comparable fold-change values for a handful of genes were obtained between Affymetrix technology and the more sensitive RTqPCR method. Ingenuity Pathway Analysis software pinpointed the up-regulation of the sterol biosynthesis pathway (P-value = 1.31e-02) involving several genes (1.95 to 4.30 fold-change values), and the modulation of various genes involved in polyamine synthesis and in pro/counter-inflammatory signaling. Our findings suggest that amastigotes exploit the M lipid and polyamine pathways to multiply efficiently, and induce a counter-inflammatory environment to expand their dermis niche.

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