Protection Against Periodontitis by Improving Mitochondrial Function in Diabetes

Diabetes is a major risk factor for severe periodontitis. This is partly due to impaired wound healing associated with concomitant failure to resolve inflammation and chronic infection. Studies from the Joslin Medalist Cohort, people with >50 years of type 1 diabetes, have reported that protective factors exist to delay the onset of severe retinopathy, nephropathy, and periodontitis, even with persistent hyperglycemia. Proteomic analysis of healthy gingival tissues from individuals with hyperglycemia versus those with periodontitis and good glycemic control showed substantial upregulation of oxidative phosphorylation, particularly mitochondrial complex I and II, as validated by immunoblot analysis. Diabetes reduced mitochondrial enzyme expression and function, measured by oxygen consumption rate in the gingiva, compared with nondiabetic mice, in parallel, with exacerbation of ligature-induced periodontal bone loss, elevation of inflammatory cytokines (Il-1b, Il-6, and Il-17a) and activation of osteoclasts. However, activation of pyruvate kinase M2 reversed diabetes and ligature-induced mitochondrial dysfunction, reduced levels of inflammatory cytokines, and mitigated periodontal bone loss, without affecting glycolytic function. These results suggested that enhancing mitochondrial protein expression and function can decrease periodontal inflammation and osteoclast activation in diabetes, thereby protecting against the onset of periodontitis and bone loss, suggesting a potential therapy for chronic wounds, even with persistent hyperglycemia.

Characterization of protective factors against periodontal inflammation with long durations of diabetes. Proteomic analysis of gingival tissue from people with type 1 diabetes >50 years and poor glycemic control without periodontitis showed elevated mitochondrial enzymes and functions. These mitochondrial dysfunctions, as well as inflammatory and osteoclast activation, were validated in diabetic mouse models of periodontitis. Elevation of mitochondrial functions by pyruvate kinase 2 activation reversed diabetes-induced gingival inflammation, osteoclast activation, and periodontitis, even in the presence of hyperglycemia. Mitochondrial activation could be a potential therapy for periodontitis and, perhaps, chronic wound healing in diabetes.