Differential response to lipopolysaccharide by JEG-3 and BeWo human choriocarcinoma cell lines

Objective: To determine the effect of lipopolysaccharide (LPS) on NF-κB gene expression and proinflammatory cytokine release from trophoblast cell models, JEG-3 and BeWo human choriocarcinoma cells.

Study design: Serum-starved JEG-3 and BeWo cells were treated with LPS (from Escherichia coli serotype 0111:B4) for 24 or 48h. Cell culture medium was collected and assayed for interleukin (IL)-1β, IL-6, IL-8, and transforming necrosis factor (TNF)-α cytokine release using enzyme-linked immunosorbent assays. RNA was extracted from the cells and real-time PCR was performed to measure NF-κB mRNA expression. All results were analyzed by one-way analysis of variance tests followed by Sidak's post hoc analysis. p<0.05 was considered statistically significant.

Results: LPS triggered an inflammatory response in JEG-3 cells by inducing a 1.5-fold increase in NF-κB mRNA expression and TNF-α release (0μg/mL: 15.13±2.14, 1μg/mL: 14.94±0.75, 10μg/mL: 23.05±4.50, p<0.05) and a 2-fold elevation in IL-6 secretion (0μg/mL: 12.54±5.44, 1μg/mL: 25.54±0.91, 10μg/mL: 24.28±4.43, p<0.05). In contrast, BeWo cells were not as sensitive to LPS exposure; NF-κB mRNA expression was unchanged between LPS-treated and control cells, whereas a small but significant 1.3-fold increase in TNF-α release was found (TNF-α: 15.45±1.53pg/mL, control: 12.24±1.00pg/mL, p<0.05). The inflammatory pathways in BeWo cells were found to be active given that treatment of these cells with IL-1β and TNF-α induced IL-6 secretion. Interestingly, 1μg/mL LPS appeared to decrease IL-6 and TNF-α release from BeWo cells. IL-1β and IL-8 secretion were not detected from either cell lines.

Conclusion: LPS activates the NF-κB pathway in JEG-3 but not BeWo human choriocarcinoma cells and this may be the reason for their differential inflammatory response to LPS exposure.