Effect of high glucose on the secretion of cytokines induced by Porphyromonas gingivalis lipopolysaccharide

Abstract

To investigate the influence of high glucose on Porphyromonasgingivalis (Pg) lipopolysaccharide (LPS) stimulating human gingival fibroblasts (HGF) to secret the cytokines. HGF were obtained from the primary culture of the tissue explants. Cells were divided into four groups, low glucose (5.5 mmol/L) + 1 mg/L Pg LPS (group A);low glucose + 10 mg/L Pg LPS (group B); high glucose (25 mmol/L) +1 mg/L Pg LPS(group C); high glucose+10 mg/L Pg LPS (group D). The levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in cell supernatants were detected by enzyme- linked immunosorbent assay at 6 h and 12 h. The expressions of toll-like receptor 2, 4 (TLR-2, 4) were examined by real-time polymerase chain reaction. After pretreatment with anti-TLR2 and anti-TLR4 monoclonal antibody in HGF, TNF-α and L-1β levels were detected. TNF-α concentration increased obviously in high glucose 6 h and 12 h after Pg LPS stimulation (P < 0.01). IL-1β secretion increased (P < 0.01). Meanwhile, TLR2, 4 mRNA expression increased, especially in high glucose+10 mg/L Pg LPS (P < 0.01). After inhibition of the TLR2, 4 in high glucose + 10 mg/L Pg LPS respectively, TNF-α level [(297.16±11.49), (390.01±12.81) ng/L] decreased (F = 166.02, P < 0.01), and IL-1β level [(49.90±4.08), (99.35±5.01) ng/L] also decreased (F = 153.51, P < 0.01). High glucose may promote Pg LPS to stimulate the secretion of TNF-α and IL-1β through regulating TLR2, 4 expression, which suggests that the elevating blood glucose precipitate in aggravating the process of periodontal disease.