The high-glucose conditions caused by diabetes mellitus (DM) exert several effects on cells, including inflammation. miR-146a, a kind of miRNA, is involved in inflammation and may be regulated mutually with reactive oxygen species (ROS), which are produced under high-glucose conditions. In the present study, we used human periodontal ligament cells (hPDLCs) to determine the effects of the high-glucose conditions of miR-146a and their involvement in the regulation of oxidative stress and inflammatory cytokines using Western blotting, PCR, ELISA and other methods. When hPDLCs were subjected to high glucose (24 mM), cell proliferation was not affected; inflammatory cytokine expression, ROS induction, interleukin-1 receptor-associated kinase 1 (IRAK1) and TNF receptor-associated factor 6 (TRAF6) expression increased, but miR-146a expression decreased. Inhibition of ROS induction with the antioxidant N-acetyl-L-cysteine restored miR-146a expression and decreased inflammatory cytokine expression compared to those under high-glucose conditions. In addition, overexpression of miR-146a significantly suppressed the expression of the inflammatory cytokines IRAK1 and TRAF6, regardless of the glucose condition. Our findings suggest that oxidative stress and miR-146a expression are mutually regulated in hPDLCs under high-glucose conditions.

Periodontitis is an inflammatory lesion in the periodontal tissue. The behavior of human periodontal ligament stem cells (hPDLSCs), which play an important role in periodontal tissue regeneration, is restricted by the influence of inflammatory mediators. Photobiomodulation therapy exerts anti-inflammatory effects. The purpose of this study was to investigate the effects of light-emitting diode (LED) irradiation on the inflammatory responses of hPDLSCs. The light source was a red LED (peak wavelength: 650 nm), and the total absolute irradiance was 400 mW/cm². The inflammatory response in hPDLSCs is induced by tumor necrosis factor (TNF)-α. Adenosine triphosphate (ATP) levels and pro-inflammatory cytokine (interleukin [IL]-6 and IL-8) production were measured 24 h after LED irradiation, and the effects of potassium cyanide (KCN) were investigated. LED irradiation at 6 J/cm² significantly increased the ATP levels and reduced TNF-α-induced IL-6 and IL-8 production. Furthermore, the inhibitory effect of LED irradiation on the production of pro-inflammatory cytokines was inhibited by KCN treatment. The results of this study showed that high-intensity red LED irradiation suppressed the TNF-α-stimulated pro-inflammatory cytokine production in hPDLSCs by promoting ATP synthesis. These results suggest that high-intensity red LED is a useful tool for periodontal tissue regeneration in chronically inflamed tissues.

Shikonin is a naturally occurring compound known for its anti-inflammatory properties and wound-healing effects. The increased production of reactive oxygen species (ROS) causes oxidative stress and influences the progression of periodontal disease. MiR-146a, a type of microRNA, is reported to be involved in the control of inflammation. This research seeks to examine the anti-inflammatory and antioxidant properties of shikonin on human gingival fibroblasts (hGFs) under inflammation induced by Interleukin (IL)-1β, which is associated with the progression of periodontitis and to further investigate the effect of shikonin on miR-146a expression. Cell proliferation, scratching, and toxicity tests were performed, and the shikonin concentration was set at 0.1 µM. The levels of ROS, miR-146a, and inflammatory cytokines were measured to examine the effects of shikonin on inflammation. The addition of shikonin reduced IL-6 by approximately 20% and reduced IL-8 by approximately 30% compared to IL-6 and IL-8 production and expression induced by IL-1β. MiR-146a expression increased 3.38-fold under IL-1β-induced inflammation but showed a decreasing trend with the addition of shikonin. These results suggest that IL-1β-induced inflammation and oxidative stress are regulated by shikonin in hGFs and are associated with the expression of miR-146a.

歯肉退縮に対する根面被覆術には様々な方法があり，現在ゴールドスタンダードである結合組織移植術（connective tissue graft：CTG）にも様々な受容床形成法が存在する。そして歯肉退縮の分類にどの術式を選択し良好な予後を収めるかは術前の診断が重要になってくる。本症例報告患者は24歳女性で，下顎中切歯2歯の歯肉退縮に続く歯の喪失について不安になり来院した。31，41部ともMaynardの分類Type4であり，歯肉退縮はMillerの歯肉退縮の分類ClassIIIおよびCairoの分類Recession Type（RT）2であった。術前コーンビームCT（CBCT）にて31，41間唇側に軽度の骨吸収がみられたが，舌側には骨吸収は認められなかった。また41根が遠心に傾いていたため，歯槽骨頂付近の歯根間距離が41，42間は狭く，31，41間は広かった。CTGを行う際，露出根面上には血液供給がなく，周囲組織の血液供給を確保できるかが重要になってくる。その血液供給には歯間乳頭が重要な役割を果たす。今回Millerの分類ClassIIIおよびCairoの分類RT2の下顎中切歯2歯に及ぶ歯肉退縮に対し，CBCTにより歯槽骨状態の把握および歯根間距離の計測を行うことで歯間乳頭の大きさを考慮し，CTGの術式として歯間乳頭への切開を行わないトンネル形成術を選択し良好な結果を得られたので報告する。