Hyperglycaemia aggravates periodontal inflamm‐aging by promoting SETDB1‐mediated LINE‐1 de‐repression in macrophages

Abstract Aim To explore whether hyperglycaemia plays a role in periodontal inflamm‐aging by inducing phenotypical transformation of macrophages, as well as the potential mechanism via SET domain‐bifurcated histone lysine methyltransferase 1 (SETDB1). Materials and Methods A hyperglycaemic mouse model was established using streptozotocin injection. The alveolar bone was analysed using micro‐computed tomography. Periodontal inflamm‐aging was detected using western blotting, quantitative real‐time PCR and immunohistochemical analysis. In vitro, RAW 264.7 macrophages were incubated with various doses of glucose. siRNA or overexpression plasmids were used to determine the regulatory mechanism of SETDB1 in macrophage senescence and inflamm‐aging under hyperglycaemic conditions. Expression and distribution of SETDB1 and long interspersed element 1 (LINE‐1) in gingival tissues of patients with or without diabetes were detected using immunofluorescent staining. Results SETDB1 expression in the periodontal tissues of patients and mice with diabetes was down‐regulated compared with that in non‐diabetic controls. SETDB1 deficiency induced senescence‐like phenotypical changes in macrophages, which aggravated periodontal inflamm‐aging in diabetic mice. Furthermore, metformin treatment rejuvenated SETDB1 activity and alleviated the hyperglycaemia‐induced periodontal inflamm‐aging. Conclusions The findings of this study show that SETDB1 regulates senescence‐like phenotypical switching of macrophages and is a potential candidate for the treatment of diabetes‐induced periodontal inflamm‐aging.