Yamamoto Tadahiro, Yuan Hang, Suzuki Shigeki, Nemoto Eiji, Saito Masahiro, Yamada Satoru
Department of Periodontology and Endodontology, Tohoku University Graduate School of Dentistry, Sendai, Japan.
Department of Restorative Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan.
J Dent Sci. 2024 Jul;19(3):1801-1810. doi: 10.1016/j.jds.2023.09.027. Epub 2023 Oct 6.
BACKGROUND/PURPOSE: Periodontal breakdown in periodontitis is exacerbated by pro-inflammatory responses of periodontal stromal cells such as periodontal ligament fibroblasts (PDLFs). Procyanidin B2 (PB2) is a ligand of the peroxisome proliferator-activated receptor (PPARγ). Herein, we investigated the expression of PPARγ isoforms in PDLFs and periodontal tissue, and examined the effects of PB2 on PPARγ isoform-dependent antiinflammatory responses.
PPARγ isoforms were examined by PCR. PPARγ isoform-dependent inflammatory functions and anti-inflammatory effects of PB2 in PDLFs were evaluated based on IL-6 expression. Co-immunoprecipitation analysis of fixed chromatin-tethered protein (CoIPfctp) was conducted to investigate the association of each PPARγ isoform with the NF-κB-transcriptional complex. The effects of PB2 on periodontitis progression were evaluated using a ligature-induced murine periodontitis model.
Three isoforms of PPARγ were expressed in PDLFs and periodontal tissues, consisting of the main full-length isoform (PPARγ) and two dominant negative isoforms that lack the ligand binding domain, namely the ubiquitously-expressed isoform (PPARγ-UBI) and unknown isoform (PPARγ-PDL). PPARγ and PPARγ-UBI were predominantly expressed. CoIP-fctp revealed that PPARγ-UBI was selectively associated with NF-κB p65, a key transcriptional factor of IL-6 expression. PB2 suppressed LPS-induced-IL-6 expression exacerbated by the over-expression of PPARγ-UBI. In the murine periodontitis model, topical application of PB2 significantly mitigated alveolar bone loss.
These results suggest that the anti-inflammatory effects of PB2 in periodontal tissues/cells are distinct, and these effects arise from the inhibition of PPARγ-UBI; hence, the application of PB2 and modification of the splicing event in three PPARγ isoforms have therapeutic potential for preventing periodontitis.
背景/目的：牙周炎中牙周组织破坏会因牙周基质细胞（如牙周膜成纤维细胞，PDLFs）的促炎反应而加剧。原花青素B2（PB2）是过氧化物酶体增殖物激活受体（PPARγ）的配体。在此，我们研究了PPARγ亚型在PDLFs和牙周组织中的表达，并检测了PB2对PPARγ亚型依赖性抗炎反应的影响。
通过PCR检测PPARγ亚型。基于白细胞介素-6（IL-6）的表达评估PPARγ亚型依赖性炎症功能以及PB2在PDLFs中的抗炎作用。进行固定染色质 tethered 蛋白的免疫共沉淀分析（CoIPfctp），以研究每种PPARγ亚型与核因子κB转录复合物的关联。使用结扎诱导的小鼠牙周炎模型评估PB2对牙周炎进展的影响。
PPARγ的三种亚型在PDLFs和牙周组织中表达，包括主要的全长亚型（PPARγ）和两种缺乏配体结合域的显性负性亚型，即普遍表达的亚型（PPARγ-UBI）和未知亚型（PPARγ-PDL）。PPARγ和PPARγ-UBI表达占主导。CoIP-fctp显示PPARγ-UBI与IL-6表达的关键转录因子核因子κB p65选择性相关。PB2抑制了由PPARγ-UBI过表达加剧的脂多糖诱导的IL-6表达。在小鼠牙周炎模型中，局部应用PB2显著减轻了牙槽骨丧失。
这些结果表明PB2在牙周组织/细胞中的抗炎作用是独特的，且这些作用源于对PPARγ-UBI的抑制；因此，应用PB2以及对三种PPARγ亚型剪接事件的修饰具有预防牙周炎的治疗潜力。
