Global gene expression analysis on the target genes of PQS and HHQ in J774A.1 monocyte/macrophage cells.

We have previously shown that PQS and HHQ, two quorum sensing molecules, can down-regulate host the innate immune responses and that this is mediated through the NF-kappaB pathway. In this study, to search for a comprehensive set of genes regulated by these quorum sensing molecules, we performed a global gene expression analysis using DNA microarray in J774A.1 monocyte/macrophage cells line. The expression of these genes was confirmed by RT-PCR. We found that PQS and HHQ down-regulated the expression of genes involved in immune responses and transcription as well as other functions, some of which are downstream of NF-kappaB pathway consistent with our previous results. PQS and HHQ inhibited LPS-induced morphological change and nitric oxide production, suggesting that they inhibit macrophage activation. However, PQS and HHQ did not affect apoptosis, suggesting that their effects on immune system are not from general alteration of cell function. This study provides insight how the quorum sensing molecules influence host cells.