Abstract:

In order to investigate whether changes in glucose concentration can up-regulate the RAGE-TLR4-MyD88-NF-κB signaling pathway of bovine alveolar macrophages (BAMs) and cause BAMs to release proinflammatory cytokines IL-1β, IL-6 and TNF-α.Groups Ⅰ, Ⅱ, Ⅲ and Ⅳ were treated with 5.5, 15.5, 25.5 mmol·L^-1 glucose and glucose (5.5 mmol·L^-1)+mannitol (20 mmol·L^-1) for 12 h to collect the cultured cells and supernatants; and 25.5 mmol·L^-1 glucose and BAMs were used for 0, 3, 6, 12, 24 h to collect the cultured cells and supernatants at each time point.RAGE, TLR4, MyD88 and NF-κB p65 mRNA levels and IL-1β, IL-6 and TNF-α concentrations in the supernatant were detected.The results showed that the levels of RAGE, TLR4, MyD88 and NF-κB p65 mRNA and the concentrations of IL-1β, IL-6 and TNF-α in group Ⅲ were significantly (P<0.01)higher than those in group Ⅰ, the concentrations of IL-1β and TNF-α in group Ⅱ were significantly(P<0.01) higher than those in group Ⅰ, the levels of MyD88, TLR4 and NF-κB p65 mRNA were significantly (P<0.05)higher than those in group Ⅰ at 3 h, and RAGE was significantly (P<0.05)higher than that at 6 h.The four gene indices all reached the peak at 12 h, which was significantly (P<0.01)higher than other time points.Only RAGE and NF-κB p65 at 24 h were significantly(P<0.01) higher than 0 h. The concentrations of IL-1β, IL-6 and TNF-α were significantly (P<0.05)higher after 3 h than 0 h, and showed a time-dependent peak at 24 h. In conclusion, 25.5 mmol·L^-1 glucose can up-regulate the gene expression in the BAMs RAGE-TLR4-MyD88-NF-κB signaling pathway and promote the release of proinflammatory cytokines IL-1β, IL-6 and TNF-α.

Key words: high glucose, bovine alveolar macrophages, inflammatory signaling pathways