Up-regulation of TLR۲ and TLR۴ in high mobility group Box۱-stimulated macrophages in pulpitis patients

Objective(s): High Mobility Group Box۱ (HMGB۱) is a nonhistone, DNA-binding protein that serves a crucial role in regulating gene transcription and is involved in a variety of proinflammatory, extracellular activities. The aim of this study was to explore whether HMGB۱ stimulation can up-regulate the expression of Toll-like Receptor ۲ (TLR۲) and Toll-like Receptor ۴ (TLR۴) on macrophages from pulpitis and to clarify the subsequent events involving Th۱۷ cells and Th۱۷ cell-associated cytokine changes. Materials and Methods: Having prepared dental pulp tissues of pulpitis and healthy controls, macrophage were isolated and cultured. Macrophages were thereafter stimulated by HMGB۱ time course. RT-QPCR, flowcytometer, immunofluorescence, Western blotting, and ELISA techniques were used in the present research. Results: Our results showed that the expression of TLR۲ and TLR۴ on macrophages stimulated with HMGB۱ increased in pulpitis compared with controls (macrophages without HMGB۱ stimulation) with a statistical significance (P<۰.۰۰۱). In addition, the levels of IL-۱۷, IL-۲۳, and IL-۶ in supernatants from cultured macrophages stimulated with HMGB۱ from pulpitis increased, and NF-kB, the downstream target of TLR۲ and TLR۴, also showed a marked elevation after macrophages’ stimulation by HMGB۱. Conclusion: The evidence from the present study suggests that the enhanced TLR۲ and TLR۴ pathways and Th۱۷ cell polarization may be due to HMGB۱ stimulation in pulpitis.

Keywords:

HMGB۱ , Pulpitis , TLR۲ , TLR۴