Background: Inflammation might link microbial exposures to insulin resistance. We investigated the cross-sectional association between periodontal microbiota, inflammation and insulin resistance. Methods: The Oral Infections, Glucose Intolerance and Insulin Resistance Study (ORIGINS) enrolled 152 diabetes-free adults (77% female) aged 20–55 years (mean = 34 ± 10). Three hundred and four subgingival plaque samples were analysed using the Human Oral Microbe Identification Microarray to measure the relative abundances of 379 taxa. C-reactive protein, interleukin-6, tumour necrosis factor-α and adiponectin were assessed from venous blood and their z-scores were summed to create an inflammatory score (IS). Insulin resistance was defined via the HOMA-IR. Associations between the microbiota and both inflammation and HOMA-IR were explored using multivariable linear regressions; mediation analyses assessed the proportion of the association explained by inflammation. Results: The IS was inversely associated with Actinobacteria and Proteobacteria and positively associated with Firmicutes and TM7 (p-values < 0.05). Proteobacteria levels were associated with insulin resistance (p < 0.05). Inflammation explained 30–98% of the observed associations between levels of Actinobacteria, Proteobacteria or Firmicutes and insulin resistance (p-values < 0.05). Eighteen individual taxa were associated with inflammation (p < 0.05) and 22 with insulin resistance (p < 0.05). No findings for individual taxa met Bonferroni-adjusted statistical significance. Conclusion: Bacterial measures were related to inflammation and insulin resistance among diabetes-free adults.
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Conflict of interest and source of funding statement The authors have stated explicitly that there are no conflicts of interest in connection with this article. This research was supported by NIH grants R00 DE018739, R21 DE022422 and R01 DK 102932 to Dr. Demmer. Dr. Demmer also received funding from a Calderone Research Award, Mailman School of Public Health, and a Pilot & Feasibility Award from the Diabetes and Endocrinology Research Center, College of Physicians and Surgeons (DK-63608 to Dr. Leibel). This publication was also supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant Number UL1 TR000040, formerly the National Center for Research Resources, Grant Number UL1 RR024156. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. We thank the following individuals for their invaluable contributions to this research: the 1199 SEIU, HS-3/SSA Area leadership including Ms. Consuelo Mclaughin, Mr. Bennett Batista, Mr. Victor Rivera; Ms. Romanita Celenti for her efforts in performing phlebotomy and processing and analysing plaque samples; Drs. Nidhi Arora, Ashwata Pokherel, Publio Silfa and Thomas Spinell for their skilled examinations and essential participant engagement. We are also profoundly grateful to the ORIGINS participants, for their participation in this research.
© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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- C-reactive protein
- insulin resistance
- tumour necrosis factor-α