Regulation and Signal Transduction of Toll-Like Receptors in Human Chorioncarcinoma Cell Lines

Problem: Toll‐like receptors (TLRs) are expressed on placental cells. The aim of this study is to analyze signaling components activated in placenta cells after TLR ligand engagement. Methods of study: In chorioncarcimoma cell lines the regulation of TLRs was determined by real time polymerase chain reaction as well as by fluorescence‐activated cell sorter analysis. Activation of NF‐κB was determined in a reporter assay system and the activation of the mitogen‐activated protein kinase signaling pathways by immunoblot analysis. Results: Both lipopolysaccharide (LPS) and DNA oligonucleotides containing unmethylated CpG motifs (CpG) induced the enhanced expression of TLR2 mRNA as well as a TLR2 surface protein expression. Functionally, incubation of JAR cells with microbial stimuli such as LPS activated NF‐κB, as well as the phosphorylation of ERK1/2 and p38 MAP kinases and secretion of interleukin‐8. Conclusion: The functional expression of TLRs on placental cells may play an important role in the initiation of an immune response in the developing fetus.