Human placenta promotes IL-8 expression through activation of JNK/SAPK and transcription factors NF-κB and AP-1 in PMA-differentiated THP-1 cells

Human placenta is a rich reservoir of diverse bioactive molecules with therapeutic potential against certain diseases such as immune disorders. In the present study, we investigated the ability of human placenta extract (HPE) to induce expression of a CXC chemokine, interleukin-8 (IL-8), in a human monocytic cell line, THP-1, differentiated into macrophages with phorbol 12-myristate 13-acetate (PMA). HPE significantly induced IL-8 mRNA and protein expressions in a dose-dependent manner. HPE-induced IL-8 expression was inhibited by a selective inhibitor of JNK/SAPK, but not by inhibitors of p38 kinase or ERK. Since IL-8 transcription is known to be regulated by nuclear factor (NF)-κB, activating protein (AP)-1 and NF for IL-6 (NF-IL6), an electrophoretic mobility shift assay was performed to examine the DNA-binding activities of these transcription factors. The DNA-binding activities of NF-κB and AP-1 increased in cells treated with HPE in a dose-dependent manner, while no change was observed in NF-IL6 binding activity under the same conditions. Taken together, these results suggest that HPE-induced IL-8 secretion occurs via activation of JNK/SAPK and transcription factors NF-κB and AP-1 in PMA-differentiated THP-1 cells.