MicroRNA expression in inflamed and noninflamed gingival tissues from Japanese patients.

Periodontitis is a chronic inflammatory disease caused by specific bacteria and viruses. Local, systemic, and environmental factors affect the rate of disease progression. Immune responses to bacterial products, and the subsequent production of inflammatory cytokines, are crucial in the destruc- tion of periodontal tissue. MicroRNAs (miRNAs) are a class of small RNAs that control various cell processes by negatively regulating protein-coding genes. In this study, we compared miRNA expression in inflamed and noninflamed gingival tissues from Japanese dental patients. Total RNAs were isolated from inflamed and noninflamed gingival tissues. miRNA expression profiles were examined by an miRNA microarray, and the data were analyzed by GeneSpring GX, Ingenuity Pathways Analysis, and the TargetScan databases. Observed miRNA expres- sion levels in inflamed gingiva were confirmed by real-time PCR. The three most overexpressed (by >2.72-fold) miRNAs were hsa-miR-150, hsa-miR-223, and hsa-miR-200b, and the three most underex- pressed (by <0.39-fold) miRNAs were hsa-miR-379, hsa-miR-199a-5p, and hsa-miR-214. In IPA analysis, hsa-miR-150, hsa-miR-223, and hsa-miR-200b were associated with inflammatory disease, organismal injury, abnormalities, urological disease, and cancer.