Palmitate-Triggered COX2/PGE2-Related Hyperinflammation in Dual-Stressed PdL Fibroblasts Is Mediated by Repressive H3K27 Trimethylation

Abstract

The interrelationships between periodontal disease, obesity-related hyperlipidemia and mechanical forces and their modulating effects on the epigenetic profile of periodontal ligament (PdL) cells are assumed to be remarkably complex. The PdL serves as a connective tissue between teeth and alveolar bone and is involved in pathogen defense and the inflammatory responses to mechanical stimuli occurring during tooth movement. Altered inflammatory signaling could promote root resorption and tooth loss. Hyperinflammatory COX2/PGE2 signaling was reported for human PdL fibroblasts (HPdLFs) concomitantly stressed with Porphyromonas gingivalis lipopolysaccharides and compressive force after exposure to palmitic acid (PA). The aim of this study was to investigate the extent to which this was modulated by global and gene-specific changes in histone modifications. The expression of key epigenetic players and global H3Kac and H3K27me3 levels were quantitatively evaluated in dual-stressed HPdLFs exposed to PA, revealing a minor force-related reduction in repressive H3K27me3. UNC1999-induced H3K27me3 inhibition reversed the hyperinflammatory responses of dual-stressed PA cultures characterized by increased COX2 expression, PGE2 secretion and THP1 adhesion. The reduced expression of the gene encoding the anti-inflammatory cytokine IL-10 and the increased presence of H3K27me3 at its promoter-associated sites were reversed by inhibitor treatment. Thus, the data highlight an important epigenetic interplay between the different stimuli to which the PdL is exposed.

GDF15 Promotes the Osteogenic Cell Fate of Periodontal Ligament Fibroblasts, thus Affecting Their Mechanobiological Response

“…For analyzing gene expression, cells were isolated with TRIzol reagent (Thermo Fisher Scientific, Carlsbad, CA, USA). RNA isolation, cDNA synthesis, and quantitative PCR were performed as previously described [ 33 , 34 , 80 ]. Briefly, 1-bromo-3-chloro-propane (Sigma-Aldrich, St. Louis, MO, USA) and centrifugation were used for the separation of RNA.…”

“…Quantitative PCR was performed with Luminaris Color HiGreen qPCR Master Mix (Thermo Fisher Scientific, Carlsbad, CA, USA) according to the manufacturer’s protocol and analyzed with qTOWER3 (Analytik Jena, Jena, Germany). Primer design was performed as previously described [ 33 , 34 , 80 ]. The quality and specificity of the primers were analyzed using melting curves and agarose gel electrophoresis.…”

Oleic acid-related anti-inflammatory effects in force-stressed PdL fibroblasts are mediated by H3 lysine acetylation associated with altered IL10 expression

“…However, in this way, an OA-related increase in H3K acetylation was simulated, but without a variety of other changes due to fatty acid treatment. The pro-inflammatory response of HPdLF to several stimuli can be limited by anti-inflammatory cytokines including interleukin 10 (IL-10) [ 39 ]. Quantitative expression analysis revealed a significant increase of IL10 transcription levels in HPdLFs exposed to FK228 ( Figure 2g ) indicating an important role of H3K acetylation in regulating IL10 gene activity.…”

“…In addition to direct binding and post-translational modifications of transcription factors, fatty acids can regulate gene expression by altering epigenetic modification such as histone marks [ 42 , 43 ]. As recently shown, FA-related changes in the epigenetic code may thereby condition hyperinflammatory responses of HPdLFs to combined mechanical and peripathogenic stimuli [ 39 ]. In the context of the MUFA oleic acid, this has been specifically shown in glucose-starved C2C12 mouse myoblast cells, which showed up-regulated H3K23 acetylation when supplemented with 200 µM OA [ 44 ].…”

GDF15 Modulates the Zoledronic-Acid-Induced Hyperinflammatory Mechanoresponse of Periodontal Ligament Fibroblasts

“…Immunofluorescent staining was performed as previously described [49][50][51]. Briefly, following 10 min fixation with paraformaldehyde (PFA, 4%), three washing steps in 1× PBS/0.1% Triton X (Triton X ® 100, Carl Roth GmbH + Co. KG, Karlsruhe, Germany) were applied.…”