Periodontitis Risk Variants at SIGLEC5 Impair ERG and MAFB Binding

A genome-wide association study meta-analysis in a European sample of stage III/IV grade C periodontitis patients ≤35 years of age identifies new risk loci

AIM

Few genome-wide association studies (GWAS) have been conducted for severe forms of periodontitis (stage III/IV grade C), and the number of known risk genes is scarce. To identify further genetic risk variants to improve the understanding of the disease aetiology, a GWAS meta-analysis in cases with a diagnosis at ≤35 years of age was performed.

MATERIALS AND METHODS

Genotypes from German, Dutch and Spanish GWAS studies of III/IV-C periodontitis diagnosed at age ≤35 years were imputed using TopMed. After quality control, a meta-analysis was conducted on 8,666,460 variants in 1306 cases and 7817 controls with METAL. Variants were prioritized using FUMA for gene-based tests, functional annotation and a transcriptome-wide association study integrating eQTL data.

RESULTS

The study identified a novel genome-wide significant association in the FCER1G gene (p = 1.0 × 10-9 ), which was previously suggestively associated with III/IV-C periodontitis. Six additional genes showed suggestive association with p < 10-5 , including the known risk gene SIGLEC5. HMCN2 showed the second strongest association in this study (p = 6.1 × 10-8 ).

CONCLUSIONS

This study expands the set of known genetic loci for severe periodontitis with an age of onset ≤35 years. The putative functions ascribed to the associated genes highlight the significance of oral barrier tissue stability, wound healing and tissue regeneration in the aetiology of these periodontitis forms and suggest the importance of tissue regeneration in maintaining oral health.

miRNAs from Inflamed Gingiva Link Gene Signaling to Increased MET Expression

Several array-based microRNA (miRNA) expression studies independently showed increased expression of miRNAs hsa-miR-130a-3p, -142-3p, -144-3p, -144-5p, -223-3p, -17-5p, and -30e-5p in gingiva affected by periodontal inflammation. We aimed to determine direct target genes and signaling pathways regulated by these miRNAs to identify processes relevant to gingival inflammatory responses and tissue homeostasis. We transfected miRNA mimics (mirVana) for each of the 7 miRNAs separately into human primary gingival fibroblasts cultured from 3 different donors. Following RNA sequencing, differential gene expression and second-generation gene set enrichment analyses were performed. miRNA inhibition and upregulation was validated at the transcript and protein levels using quantitative reverse transcriptase polymerase chain reaction, Western blotting, and reporter gene assays. All 7 miRNAs significantly increased expression of the gene MET proto-oncogene, receptor tyrosine kinase (MET). Expression of known periodontitis risk genes CPEB1, ABCA1, and ATP6V1C1 was significantly repressed by hsa-miR-130a-3p, -144-3p, and -144-5p, respectively. The genes WASL, ENPP5, ARL6IP1, and IDH1 showed the most significant and strongest downregulation after hsa-miR-142-3p, -17-5p, -223-3p, and -30e-5p transfection, respectively. The most significantly regulated gene set of each miRNA related to cell cycle (hsa-miRNA-144-3p and -5p [Padj = 4 × 10-40 and Padj = 4 × 10-6], -miR-17-5p [Padj = 9.5 × 10-23], -miR-30e-5p [Padj = 8.2 × 10-18], -miR-130a-3p [Padj = 5 × 10-15]), integrin cell surface interaction (-miR-223-3p [Padj = 2.4 × 10-7]), and interferon signaling (-miR-142-3p [Padj = 5 × 10-11]). At the end of acute inflammation, gingival miRNAs bring together complex regulatory networks that lead to increased expression of the gene MET. This underscores the importance of mesenchymal cell migration and invasion during gingival tissue remodeling and proliferation in restoring periodontal tissue homeostasis after active inflammation. MET, a receptor of the mitogenic hepatocyte growth factor fibroblast secreted, is a core gene of this process.

Circulating miRNAs as Epigenetic Mediators of Periodontitis and Preeclampsia Association

Objective

Periodontal disease has been associated with pregnancy complications including preeclampsia. This bioinformatic study is aimed at investigating the possible role of circulating microRNAs (miRNAs) as mediators of the association between maternal periodontal disease and preeclampsia.

Methods

Peripheral blood miRNA profiles of periodontitis and controls were sought from Gene Expression Omnibus (GEO), and differential expression analysis was performed. Experimentally validated circulating miRNAs associated with preeclampsia were determined from the Human MicroRNA Disease Database (HMDD v3.0). Venn diagrams were drawn to identify shared circulating differential miRNAs (DEmiRNAs). Significantly enriched target genes, KEGG pathways, and Gene Ontology (GO) terms for the set of shared DEmiRNA were predicted using miRNA enrichment analysis and annotation tool (miEAA v 2.0). Additionally, the shared DEmiRNA-enriched target genes were analyzed for enriched WikiPathways, BioCarta metabolic pathways, and tissue proteins in the human proteome map.

Results

Among 183 circulating DEmiRNA in periodontitis and 60 experimentally validated miRNA in preeclampsia, 9 shared DEmiRNA were identified. The top among 32 overrepresented target genes included MAFB, PSAP, and CDK5RAP2, top among 14 enriched KEGG pathways were renin-angiotensin system and graft-versus-host disease, and that among enriched 44 GO profiles included “positive regulation of epidermal growth factor-activated receptor activity” and “sequestering of calcium ion.” In the overrepresented target gene set, among 10 enriched WikiPathways, the top included “NAD metabolism, sirtuins, and aging” and “regulation of Wnt/B-catenin signaling by small molecule compounds” and PPAR-related mechanisms was top among 13 enriched BioCarta metabolic pathways.

Conclusion

A circulating 9-DEmiRNA set was significantly linked to both periodontitis and preeclampsia. Enrichment analysis identified specific genes, pathways, and functional mechanisms, which may be epigenetically altered and thereby mediate the biological association of periodontitis and preeclampsia.