High glucose condition aggravates inflammatory response induced by Porphyromonas gingivalis in THP-1 macrophages via autophagy inhibition

Abstract Background Porphyromonase gingivalis (P. gingivalis) is a type of the bacteria that cause periodontitis, which is highly correlated with systemic diseases such as diabetes. However, the impact of hyperglycaemia on periodontitis is unclear. In the present study, we investigated the effects of high glucose levels on the response to P. gingivalis infection.Results The expression of P. gingivalis-induced interleukin-1β (IL-1β) and inflammasomes increased with increasing glucose concentration. High glucose conditions suppressed P. gingivalis–induced autophagy in human acute monocytic leukaemia cell line (THP-1) macrophages. Zingerone increased autophagy and alleviated P. gingivalis-induced inflammatory response in THP-1 macrophages under high glucose conditions. In addition, alveolar bone loss due to P. gingivalis infection was significantly higher in diabetic mice than in wild-type mice. P. gingivalis-induced inflammation in bone marrow-derived macrophages of diabetic mice was increased; however, it was decreased by zingerone treatment.Conclusions High-glucose conditions aggravated the inflammatory response to P. gingivalis infection through the suppression of autophagy, suggesting that autophagy induction could potentially be used to treat periodontitis in diabetes.