Effect of imiquimod on cytokine induction in first trimester trophoblasts

Imiquimod (IQ) is used clinically for the topical treatment of external genital warts. IQ is an immune response modifier and induces the expression of interferon-alpha and other cytokines in human Peripheral Blood Monocytes (PBMC). Trophoblasts have been previously shown to express inflammatory cytokines upon lipopolysaccharide (LPS) stimulation. The objective of this study was to evaluate the ability of IQ to induce transcription of cytokines in trophoblasts.

A transformed human first trimester trophoblast cell line, HTR-8/SVneo, was cultured in DMEM containing IQ at concentrations of 0 to 5.0 microg/ml. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) viability assays were conducted to control for any drug-induced cell death. Total RNA was isolated from trophoblasts at 0, 8 and 24 hours of culture and Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was conducted using specific amplimers for the inflammatory cytokines interleukin (IL)-1alpha, IL-1beta, IL-6 and IL-8. RT-PCR of beta-actin was performed to control for equal RNA loading.

RT-PCR was unable detect an increase in either IL-1alpha, IL-1beta, IL-6 or IL-8 mRNA in first trimester trophoblasts cultured in the presence of 0 to 5.0 microg/mL of IQ for up to 24 hours. RT-PCR confirmed equal RNA loading and MTT viability assays did not show loss of cell viability at concentrations of IQ up to 5.0 microg/ml.

IQ, at the concentrations tested, did not induce the transcriptional expression of inflammatory cytokines in human first trimester trophoblasts. These data suggest that IQ would not induce the expression of inflammatory cytokines in placental trophoblasts.