Diet-Induced Obesity and Its Differential Impact on Periodontal Bone Loss

• Published in: Journal of dental research Vol. 95; no. 2; pp. 223 - 229
• Main Authors: Muluke, M., Gold, T., Kiefhaber, K., Al-Sahli, A., Celenti, R., Jiang, H., Cremers, S., Van Dyke, T., Schulze-Späte, U.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01-02-2016; SAGE PUBLICATIONS, INC
• Subjects: Alveolar bone; Alveolar Bone Loss - etiology; Alveolar Bone Loss - immunology; Alveolar Bone Loss - microbiology; Animals; Body Weight; Body weight gain; Bone loss; Bone remodeling; Bone Remodeling - physiology; Bone turnover; Calories; Cells, Cultured; Collagen; Collagen Type I - blood; Cross-linking; Dentistry; Diet, High-Fat - adverse effects; High fat diet; Homeostasis; Inflammation; Inoculation; Interleukin-6 - blood; Lipid metabolism; Male; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Nutrition research; Obesity; Obesity - complications; Obesity - immunology; Obesity - microbiology; Oleic acid; Oleic Acid - blood; Oleic Acid - pharmacology; Osteoblasts; Osteoblasts - immunology; Osteoblasts - microbiology; Osteocalcin; Osteocalcin - blood; Osteoclasts; Osteoclasts - immunology; Osteoclasts - microbiology; Palmitic acid; Palmitic Acid - blood; Palmitic Acid - pharmacology; Peptide Fragments - blood; Peptides - blood; Periodontal diseases; Placebos; Porphyromonas gingivalis; Porphyromonas gingivalis - physiology; Procollagen; Procollagen - blood; Random Allocation; Research Reports; Studies; Toll-Like Receptor 2 - analysis; Toll-Like Receptor 4 - analysis; Tumor Necrosis Factor-alpha - blood; Tumor necrosis factor-TNF; Tumor necrosis factor-α; United States > US; bone metabolism; osteoclast; inflammation; palmitic acid; oleic acid; high-fat diet
• ISSN: 0022-0345; 1544-0591
• DOI: 10.1177/0022034515609882

Obesity is associated with abnormal lipid metabolism and impaired bone homeostasis. The aim of our study was to investigate the impact of specific elevated fatty acid (FA) levels on alveolar bone loss in a Porphyromonas gingivalis–induced model of periodontal disease and to analyze underlying cellular mechanisms in bone-resorbing osteoclasts and bone-forming osteoblasts in mice. Four-week-old male C57BL/6 mice were randomly divided in groups and subjected to a palmitic acid (PA)– or oleic acid (OA)–enriched high-fat diet (HFD) (20% of calories from FA) or a normal caloric diet (C group) (10% of calories from FA) for 16 wk. Starting at week 10, mice were infected orally with P. gingivalis (W50) or placebo to induce alveolar bone loss. Animals were sacrificed, and percentage fat, serum inflammation (tumor necrosis factor [TNF]-α), and bone metabolism (osteocalcin [OC], carboxy-terminal collagen crosslinks [CTX], and N-terminal propeptides of type I procollagen [P1NP]) markers were measured. Osteoblasts and osteoclasts were cultured in the presence of elevated PA or OA levels and exposed to P. gingivalis. Animals on FA-enriched diets weighed significantly more compared with animals on a normal caloric diet (P < 0.05). Both obese groups had similar percentages of fat (P = nonsignificant); however, alveolar bone loss was significantly greater in animals that were on the PA-enriched HFD (P < 0.05). TNF-α levels were highest in the PA group (P < 0.001) and increased in all groups in response to P. gingivalis inoculation (P < 0.01), whereas bone remodeling markers OC, CTX, and P1NP were lowest in the PA group (P < 0.001) and highest in the C group. Bacterial challenge decreased bone metabolism markers in all groups (P < 0.01). Further, osteoclasts showed an augmented inflammatory response to P. gingivalis in the presence of hyperlipidemic PA levels as opposed to OA cultures, which responded similarly to controls. These findings indicate that the specific FA profile of diet rather than weight gain and obesity alone modulates bone metabolism and can therefore influence alveolar bone loss.