The regulatory processes in developmental biology research are significantly influenced by long non-coding RNAs (lncRNAs). However, the dynamics of lncRNA expression during human tooth development remain poorly understood. In this research, we examined the lncRNAs present in the dental epithelium (DE) and dental mesenchyme (DM) at the late bud, cap, and early bell stages of human fetal tooth development through bulk RNA sequencing. Developmental regulators co-expressed with neighboring lncRNAs were significantly enriched in odontogenesis. Specific lncRNAs expressed in the DE and DM, such as PANCR, MIR205HG, DLX6-AS1, and DNM3OS, were identified through a combination of bulk RNA sequencing and single-cell analysis. Further subcluster analysis revealed lncRNAs specifically expressed in important regions of the tooth germ, such as the inner enamel epithelium and coronal dental papilla (CDP). Functionally, we demonstrated that CDP-specific DLX6-AS1 enhanced odontoblastic differentiation in human tooth germ mesenchymal cells and dental pulp stem cells. These findings suggest that lncRNAs could serve as valuable cell markers for tooth development and potential therapeutic targets for tooth regeneration.
Humans ; RNA, Long Noncoding/metabolism* ; Odontogenesis/genetics* ; Tooth Germ/embryology* ; Cell Differentiation ; Gene Expression Regulation, Developmental ; Mesoderm/metabolism* ; Tooth/embryology* ; Gene Expression Profiling ; Sequence Analysis, RNA ; Dental Pulp/cytology*

Smoking is a well-established risk factor for periodontitis, yet the precise mechanisms by which smoking contributes to periodontal disease remain poorly understood. Recent advances in spatial transcriptomics have enabled a deeper exploration of the periodontal tissue microenvironment at single-cell resolution, offering new opportunities to investigate these mechanisms. In this study, we utilized Visium HD single-cell spatial transcriptomics to profile gingival tissues from 12 individuals, including those with periodontitis, those with smoking-associated periodontitis, and healthy controls. Our analysis revealed that smoking disrupts the epithelial barrier integrity, induces fibroblast alterations, and dysregulates fibroblast-epithelial cell communication, thereby exacerbating periodontitis. The spatial analysis showed that endothelial cells and macrophages are in close proximity and interact, which further promotes the progression of smoking-induced periodontal disease. Importantly, we found that targeting the endothelial CXCL12 signalling pathway in smoking-associated periodontitis reduced the proinflammatory macrophage phenotype, alleviated epithelial inflammation, and reduced alveolar bone resorption. These findings provide novel insights into the pathogenesis of smoking-associated periodontitis and highlight the potential of targeting the endothelial-macrophage interaction as a therapeutic strategy. Furthermore, this study establishes an essential information resource for investigating the effects of smoking on periodontitis, providing a foundation for future research and therapeutic development for this prevalent and debilitating disease.
Humans ; Gingiva/cytology* ; Smoking/adverse effects* ; Male ; Periodontitis/pathology* ; Single-Cell Analysis ; Female ; Adult ; Middle Aged ; Macrophages ; Fibroblasts ; Endothelial Cells ; Case-Control Studies ; Chemokine CXCL12/metabolism*

Understanding the pattern and molecular mechanisms of tooth, maxilla and mandible development is the prerequisite for studying their regeneration. Tooth development can be divided into three stages: bud-bell stage, tooth crown development stage and tooth root development stage. During these processes, key genes show spatial and temporal expression pattern. Tooth development is a complex process involving interactions between dental epithelium and mesenchyme, precise regulations of enamel knots in cusp patterning, as well as successful eruption into the oral cavity under proper biomechanical stress and signaling transductions. The development of tooth, maxilla and mandible, all of which originate from the first branchial arch, is independent and regulates each other to form a whole during development. Any developmental defects of them will ultimately cause defects to the others. In this paper, we briefly reviewed the development of tooth, maxilla and mandible, proposed that the homeostasis of microenvironment is critical for their development. Moreover, we reviewed the role of Meckel’s cartilage, a special structure and signaling mechanism during mandible development. At last, we proposed an integrated development model of tooth, maxilla and mandible. We also hope that the regeneration of fully functional tooth, maxilla and mandible in human can be achieved based on fundamental knowledge we have gained so far.

Although mesenchymal stem cell-derived exosomes (MSC-exos) have been shown to have therapeutic effects in experimental periodontitis, their drawbacks, such as low yield and limited efficacy, have hampered their clinical application. These drawbacks can be largely reduced by replacing the traditional 2D culture system with a 3D system. However, the potential function of MSC-exos produced by 3D culture (3D-exos) in periodontitis remains elusive. This study showed that compared with MSC-exos generated via 2D culture (2D-exos), 3D-exos showed enhanced anti-inflammatory effects in a ligature-induced model of periodontitis by restoring the reactive T helper 17 (Th17) cell/Treg balance in inflamed periodontal tissues. Mechanistically, 3D-exos exhibited greater enrichment of miR-1246, which can suppress the expression of Nfat5, a key factor that mediates Th17 cell polarization in a sequence-dependent manner. Furthermore, we found that recovery of the Th17 cell/Treg balance in the inflamed periodontium by the local injection of 3D-exos attenuated experimental colitis. Our study not only showed that by restoring the Th17 cell/Treg balance through the miR-1246/Nfat5 axis, the 3D culture system improved the function of MSC-exos in the treatment of periodontitis, but also it provided a basis for treating inflammatory bowel disease (IBD) by restoring immune responses in the inflamed periodontium.
Colitis ; Exosomes ; Humans ; Periodontitis/therapy* ; Periodontium ; T-Lymphocytes, Regulatory ; Th17 Cells