FTO modulates the transition from pro-inflammation towards recovery by regulating Socs1 m6A methylation under mechanical microenvironments

Abstract

Periodontitis is a pathological infection that destroys tooth-supporting tissues, eventually leading to tooth loss. Inappropriate orthodontic intervention can exacerbate disease progression. Hence, orthodontic treatment in periodontally compromised patients is advised only after the complete resolution of the underlying periodontal inflammation. Macrophage activation, which is intricately regulated by multiple genes, signalling pathways and epigenetic modifications, is a significant variable that impacts the pathogenesis of periodontitis. Recent studies have revealed that inflammatory response can be modulated through N6-methyladenosine (m6A) mRNA modification, opening up a new research avenue. The oral cavity is a dynamic environment subject to various mechanical cues, including chewing and jaw movements and orthodontic treatments. However, the role of m6A methylation in regulating macrophage inflammation under mechanical conditions remains unclear. The present study aims to explore the functions of m6A methylation in macrophage activation and its effects on macrophage inflammation in periodontitis, particularly focusing on the fat mass and obesity-associated (FTO) gene (m6A eraser) and its interactions with the suppressor of cytokine signalling 1 (Socs1) mRNA, a critical gene involved in inflammation modulation. This study has been organised into three different sections, and each section is aimed at exploring a specific aspect of the function and expression of FTO and SOCS1. The first section investigates the role and expression patterns of FTO and SOCS1 under mechanical stimulation. The second section focuses on the impact of FTO on the initiation and progression of inflammation through the action of SOCS1 in response to alterations in stiffness. Finally, the third section examines the function of FTO in inflammation caused by macrophages through the regulation of SOCS1 owing to cyclic stretch-induced alterations in the regulation of inflammation. We performed various experiments, including data mining from the Gene Expression Omnibus (GEO) database, CRISPR/Cas9 analysis, methylated (m6A) RNA immunoprecipitation (MeRIP), chromatin immunoprecipitation (ChIP), RNA immunoprecipitation (RIP), immunofluorescence assay, real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting, to investigate the underlying intrinsic mechanisms at the molecular and protein levels in this study. Our results showed that the inflammatory response of macrophages and the overall m6A level were positively correlated with stiffness and negatively correlated with the cyclic stretch. FTO regulation was essential for the inflammatory response of macrophages under mechanical stimulation and for m6A modification of Socs1. The deletion of FTO showcased its importance under mechanical conditions and determined to operate the negative feedback control by altering the m6A modification of Socs1 mRNA upon mechanical stimulation. The study findings provide a better understanding of the molecular mechanisms underlying mechanically associated inflammation and the establishment of revolutionary therapeutic approaches to treat disorders triggered by mechanical stimulation. The study findings may also provide revolutionary strategies for the safe and efficient orthodontic treatment of periodontally compromised patients by understanding the intricate interplay between FTO, SOCS1 and mechanical stimulation in controlling inflammation.