METTL3-mediated m6A modifications of NLRP3 accelerate alveolar bone resorption through enhancing macrophage pyroptosis

Abstract Patients with diabetes are twice as likely to suffer from periodontitis (PD) than those without diabetes, and diabetes-associated PD is distinguished by increased inflammation and aggravated tissue damage. However, the underlying mechanisms remain largely unknown, leading to undetermined effective treatment for diabetes-associated PD. One of the most significant epigenetic alterations, N6-methyladenosine (m6A) modifications are implicated in a number of developmental and pathological processes. Here, we found that Methyltransferase-like 3 (METTL3) expression was upregulated in diabetes-associated PD mice and macrophages under Porphyromonas gingivalis and high glucose stimulation. Functionally, m6A RNA hypermethylation and pyroptosis were eliminated by METTL3 knockdown, but more significant alterations were brought about by METTL3 overexpression. Moreover, using methylation RNA immunoprecipitation, nod-like receptor family pyrin domain-containing 3 (NLRP3) was found to be a target of METTL3. Mechanistically, METTL3 increased m6A methylation level of NLRP3 and further affects macrophage pyroptosis. Binding of insulin-like growth factor 2 binding protein 3 (IGF2BP3) to the m6A-modified domains of NLRP3 was necessary for its stability. Lastly, the silencing of METTL3 mediated by adeno-associated virus 9 (AAV9) ameliorated periodental inflammation and alveolar bone loss in diabetes-associated PD mice. Collectively, we have shown that METTL3 induced m6A alterations of NLRP3 and enhanced its stability through pathways depended on IGF2BP3, thereby inducing macrophage pyroptosis in diabetes-associated PD progression, providing evidence that the METTL3/NLRP3 axis is a new and promising target for treating diabetes-associated PD.