A supplemental appendix to this article is published electronically only at http://jdr.sagepub.com/supplemental. AbstrActTo gain insights into the in vivo function of miRNAs in the context of periodontitis, we examined the occurrence of miRNAs in healthy and diseased gingival tissues and validated their in silico-predicted targets through mRNA profiling using whole-genome microarrays in the same specimens. Eighty-six individuals with periodontitis contributed 198 gingival papillae: 158 'diseased' (bleeding-on-probing, PD > 4 mm, and AL ≥ 3 mm) and 40 'healthy' (no bleeding, PD ≤ 4 mm, and AL ≤ 2 mm). Expression of 1,205 miRNAs was assessed by microarrays, followed by selected confirmation by quantitative RT-PCR. Predicted miRNA targets were identified and tested for enrichment by Gene Set Enrichment Analysis (GSEA). Enriched gene sets were grouped in functional categories by DAVID and Ingenuity Pathway Analysis. One hundred fifty-nine miRNAs were significantly differentially expressed between healthy and diseased gingiva. Four miRNAs (hsa-miR-451, hsa-miR-223, hsamiR-486-5p, hsa-miR-3917) were significantly overexpressed, and 7 (hsa-miR-1246, hsa-miR-1260, hsa-miR-141, hsa-miR-1260b, hsa-miR-203, hsa-miR-210, hsa-miR-205*) were underexpressed by > 2-fold in diseased vs. healthy gingiva. GSEA and additional filtering identified 60 enriched miRNA gene sets with target genes involved in immune/inflammatory responses and tissue homeostasis. This is the first study that concurrently examined miRNA and mRNA expression in gingival tissues and will inform mechanistic experimentation to dissect the role of miRNAs in periodontal tissue homeostasis and pathology.

Gingival tissue transcriptomes provide a valuable scientific tool for further hypothesis-driven studies of the pathobiology of periodontitis.

BackgroundPeriodontitis and Alzheimer disease (AD) are associated with systemic inflammation. This research studied serum IgG to periodontal microbiota as possible predictors of incident AD.MethodsUsing a case-cohort study design, 219 subjects (110 incident AD cases and 109 controls without incident cognitive impairment at last follow-up), matched on race-ethnicity, were drawn from the Washington Heights-Inwood Columbia Aging Project (WHICAP), a cohort of longitudinally followed northern Manhattan residents aged >65 years. Mean follow-up was five years (SD 2.6). In baseline sera, serum IgG levels were determined for bacteria known to be positively or negatively associated with periodontitis (Porphyromonas gingivalis, Tannerella forsythia, Actinobacillus actinomycetemcomitans Y4, Treponema denticola, Campylobacter rectus, Eubacterium nodatum, and Actinomyces naeslundii genospecies-2). In all analyses, we used antibody threshold levels shown to correlate with presence of moderate-severe periodontitis.ResultsMean age was 72 years (SD 6.9) for controls, and 79 years (SD 4.6) for cases (p<0.001). Non-Hispanic Whites comprised 26%, non-Hispanic Blacks 27%, and Hispanics 48% of the sample. In a model adjusting for baseline age, sex, education, diabetes mellitus, hypertension, smoking, prior history of stroke, and apolipoprotein E genotype, high anti-A. naeslundii titer (>640 ng/ml, present in 10% of subjects) was associated with increased risk of AD (HR = 2.0, 95%CI: 1.1–3.8). This association was stronger after adjusting for other significant titers (HR = 3.1, 95%CI: 1.5–6.4). In this model, high anti-E. nodatum IgG (>1755 ng/ml; 19% of subjects) was associated with lower risk of AD (HR = 0.5, 95%CI: 0.2–0.9).ConclusionsSerum IgG levels to common periodontal microbiota are associated with risk for developing incident AD.

These data suggest that PAG(+) patients may demonstrate phenotypic differences as indicated by elevated levels of IL-1beta in GCF.