Acsl1-Mediated Fatty Acid Synthesis Impairs Osseointegration in Type 1 Diabetes

Abstract

Diabetes mellitus is considered a relative contraindication to oral implant therapy, as hyperglycemia frequently precipitates vascular and osseous pathologies. Although clinicians routinely prioritize glycemic control before initiating implant-related treatment plans, diabetic patients often exhibit impaired osseointegration. However, the specific mechanisms remain to be elucidated. Emerging evidence suggests that this refractory bone loss is mediated by trained immunity, a process in which innate immune cells retain an epigenetic memory of prior inflammatory stimuli and mount an exaggerated response upon secondary challenge such as the invasive implantation process or inflammatory insult. Here, integrating RNA-seq, metabolomics, and transposase-accessible chromatin using sequencing analyses, we demonstrate that stringent glycemic control in type 1 diabetes fails to normalize the fatty acid biosynthetic process, which remains persistently activated and potentiates macrophage-mediated inflammation and osteoclastogenesis when experiencing the secondary stimuli. Mechanistically, prior hyperglycemic exposure enhances chromatin accessibility while sustaining Acsl1 transcription by H3K4me1 epigenetic modification at the Acsl1 locus in macrophages. This epigenetic imprint augments fatty acid anabolism, amplifies proinflammatory cytokine production, and accelerates osteoclastic differentiation, ultimately compromising osseous repair. Collectively, our findings reveal that diabetes-induced H3K4me1 modification at Acsl1 drives metabolic reprogramming underpinning trained immunity and consequent bone damage. Targeting H3K4me1 or Acsl1 therefore represents a promising therapeutic strategy to improve implant osseointegration and skeletal regeneration in diabetic patients.