Gingival tissue transcriptomes in experimental gingivitis

Abstract

We investigated the sequential gene expression in the gingiva during the induction and resolution of experimental gingivitis. Twenty periodontally and systemically healthy non-smoking volunteers participated in a 3-week experimental gingivitis protocol, followed by debridement and 2-week regular plaque control. We recorded clinical indices and harvested gingival tissue samples from four interproximal palatal sites in half of the participants at baseline, Day 7, Day 14 and Day 21 (the "induction phase"), and at Day 21, Day 25, Day 30 and Day 35 in the other half (the "resolution phase"). RNA was extracted, amplified, reversed transcribed, amplified, labelled and hybridized using Affymetrix Human Genome U133Plus2.0 microarrays. Paired t-tests compared gene expression changes between consecutive time points. Gene ontology analyses summarized the expression patterns into biologically relevant categories. The median gingival index was 0 at baseline, 2 at Day 21 and 1 at Day 35. Differential gene regulation peaked during the third week of induction and the first 4 days of resolution. Leucocyte transmigration, cell adhesion and antigen processing/presentation were the top differentially regulated pathways. Transcriptomic studies enhance our understanding of the pathobiology of the reversible inflammatory gingival lesion and provide a detailed account of the dynamic tissue responses during the induction and resolution of experimental gingivitis.