TSP758 - Genome-wide transcriptional and functional analysis of human T lymphocytes exposed to benzo[a]pyrene Public

Polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (B[a]P), are widely distributed carcinogenic and immunotoxic environmental contaminants, known to affect T lymphocytes. Despite extensive studies conducted, the molecular targets and pathways involved in their immunotoxic effects in human T lymphocytes remain unknown. Here, we analysed the gene expression profile of primary human T lymphocytes treated by the prototypical PAH, B[a]P using a microarray-based transcriptome analysis. After a-48h exposure to B[a]P, we identified 158 genes differentially expressed in T lymphocytes including not only genes well-known to be affected by PAHs such as the cytochromes P450 (CYP) 1A1 and 1B1, and the proto-oncogene c-KIT but also other ones not previously shown to be targeted by B[a]P. We further confirmed by RT-qPCR the altered expression levels of some of these genes encoding the gap junction beta-2 (GJB2) and beta-6 (GJB6) proteins, or the interferon-induced proteins 44 (IFI44), 44L (IFI44L), p78 (MX1), with helicase C domain (IFIH1), and with tetratricopeptide repeats 2 (IFIT2) and 3 (IFIT3). Functional enrichment analysis revealed that those candidates were significantly associated with the aryl hydrocarbon and interferon signalling pathways; it also revealed a clear alteration in essential biological functions, mainly those related to “cellular movement” especially linked to T lymphocyte recruitment. These data were confirmed by RT-qPCR assays for some selected genes such as the chemokines (C-C motif) ligands CCL3, CCL3L3, as well as the cell adhesion protein like selectin L (SELL) or the surface membrane G-protein coupled receptor 15 (GPR15). Using functional tests in transwell migration experiments, B[a]P was shown to significantly decrease the chemokine (C-X-C motif) ligand 12 (CXCL12)-induced chemotaxis of T lymphocytes, as well as their transendothelial migration. Overall, the present study opens the way to unsuspected responsive pathway of interest, i.e., T lymphocyte migration, providing a broader understanding of the molecular basis of the immunotoxicity of PAHs.