[Optimization and evaluation of an inflammatory cell model in LPS-stimulated PMA-differentiated THP-1 cells]

Objective To develop an optimal inflammatory cell model from lipopolysaccharide (LPS)-stimulated phorbol ester (PMA)-differentiated THP-1 cells, and investigate its response to anti-inflammatory agent phosphodiesterase inhibitor rolipram. Methods THP-1 cells were differentiated by PMA and stimulated by LPS to release inflammatory factors in cell supernatants, like tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), which were detected by ELISA. The doses and durations of both PMA and LPS treatment were optimized to develop the inflammatory cell model. Rolipram was added along with LPS after PMA differentiation to assess the response of cells to the anti-inflammatory agent. Results THP-1 cells showed no significant differences in cell morphology between PMA treatment for 24 hours and for 48 hours, but significantly high levels of TNF-α and IL-6 were released under LPS treatment. TNF-α level increased significantly after the differentiation by PMA at 100 ng/mL in comparison with that at 50 ng/mL, and it increased in a LPS dose-depended manner untill a plateau at 0.2 μg/mL LPS; the secretion level of IL-6 increased remarkably when THP-1 cells were induced by PMA at 100 ng/mL and stimulated by LPS≥1 μg/mL. The inflammatory cell model made using PMA at 100 ng/mL and LPS at 0.5 μg/mL was more sensitive to the anti-inflammatory agent rolipram, compared with that by 0.1 μg/mL LPS. Conclusion PMA at 100 ng/mL was selected for the differentiation of THP-1 cells with the enhanced responsiveness to LPS stimulation; THP-1 cells by the induction of PMA at 100 ng/mL coupled with the stimulation of LPS at no less than 0.2 μg/mL was an optimal inflammatory cell model for significant secretion of TNF-α and IL-6, which was sensitive to the action of anti-inflammatory agents.