Genome-wide transcriptional and functional analysis of human T lymphocytes treated with benzo[a]pyrene

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 analyzed the gene expression profile of primary human T lymphocytes treated with the prototypical PAH, B[a]P using a microarray-based transcriptome analysis. After a 48-h 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 such as genes encoding the gap junction beta-2 (GJB2) and beta-6 (GJB6) proteins. Functional enrichment analysis revealed that those candidates were significantly associated with the aryl hydrocarbon (AhR) and interferon (IFN) signalling pathways; it also revealed a clear alteration in essential biological functions, mainly those related to T lymphocyte recruitment. These data were confirmed by RT-qPCR assays for some selected genes such as the chemokine (C-C motif) ligand CCL3, and the cell adhesion protein like selectin L (SELL). 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 and transendothelial migration of T lymphocytes. 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. Independent T lymphocyte cultures isolated from 16 blood donors, each available in CTR (dimethylsulfoxide) and B[a]P-treated conditions were performed. Equal amounts of RNAs were pooled from these cultures to constitute four equimolar pools with four different blood donors per pool. Each pool was hybridized to Human Clariom™ S GeneChip.