Inflammatory cytokine secretion by THP-1 cells exposed to Porphyromonas gingivalis


Nejat Düzgüneş: 0000-0001-6159-1391


Biomedical Sciences

Document Type

Conference Presentation

Conference Title

12th Annual Bay Area Microbial Pathogenesis Symposium (BAMPS XII)


Mission Bay Campus of UCSF, San Francisco, CA

Conference Dates

March 28, 2009

Date of Presentation



Objectives: Interleukin-18 (IL-18) is a pro-inflammatory cytokine that plays an essential role in the T-cell response and is elevated in inflammatory diseases such as periodontal disease. Porphyromonas gingivalis (Pg) is one of the most important bacterial pathogens that contribute to pathogenesis of chronic periodontitis. Here we examined the IL-18 levels expressed by differentiated macrophage-like THP-1 cells after exposure to live and heat-killed Pg and to E.coli LPS. Methods: THP-1 cells were differentiated with phorbol 12-myristate 13-acetate (PMA) for 5 days at 37°C. Pg grown in chopped meat medium under anaerobic conditions, was added to differentiated THP-1 cells, at ratios of 2-100 bacteria/cell, and incubated at 37°C for 24 h. IL-18 was determined by ELISA. The Multi-Analyte Profiler ELISArray kit was used to profile other pro-inflammatory cytokines and chemokines. Values were compared to that obtained with differentiated THP-1 cells treated with medium alone. Results: Exposure to Pg at ratios of 20, 50, and 100 bacteria/cell induced significant expression of IL-18 after 24 h. For example, treatment with live and heat-killed Pg at 100 Pg/cell produced 174.3 ± 41.3 and 118.0 ± 17.3 pg IL-18/ml, respectively. THP-1 cells treated with heated and regular conditioned Pg medium produced the same level of IL-18 (~124.5 pg/ml). Treatment with E. coli LPS at 50 and 100 ng/ml resulted in the production of 61.1 ± 3.6 pg/ml IL-18. Analysis by the Multi-Analyte Profiler ELISA indicated the stimulation of IL-1β, IL-12 and TNF-α. Conclusions: P. gingivalis significantly increased IL-18 secretion by differentiated THP-1 macrophage-like cells. Our results suggest that Pg factors other than LPS also contribute to the activation of THP-1 cells and production of IL-18. Supported by Research Pilot Project Award 03-Activity 064 from the University of the Pacific, Arthur A. Dugoni School of Dentistry (A. Kim).

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