Journal of dental research最新文献

Although annexin A1 (ANXA1) is known to mediate inflammatory responses through N-formyl peptide receptor 2 (FPR2), the role of the ANXA1-FPR2 signaling pathway in periodontal disease remains unclear. This study investigated the contribution of this pathway to the pathophysiology of periodontal disease. Using a ligature-induced mouse model, we performed histologic analyses to examine ANXA1 and FPR2 expression. We observed upregulation of ANXA1 and FPR2 within the gingiva and periodontal ligament. In vitro analysis of human periodontal ligament cells revealed that interleukin 1β (IL-1β)-induced secretion of IL-8 and granulocyte-macrophage colony-stimulating factor was significantly increased in the presence of WRW4, an FPR2 antagonist. Furthermore, IL-1β-mediated upregulation of IL-8 was significantly enhanced in human periodontal ligament cells by silencing ANXA1 and FPR2 expression via small interfering RNAs. The effect of the ANXA1-FPR2 signaling pathway on periodontal tissue destruction was also examined in murine periodontitis under daily administration of WRW4 or an ANXA1 N-terminal mimetic peptide, Ac2-26, with micro-computed tomography and histologic analyses. WRW4 administration significantly intensified alveolar bone resorption, increased the number of osteoclasts on the alveolar bone surface, and dilated blood vessels in the periodontal ligament. Conversely, Ac2-26 administration significantly mitigated alveolar bone resorption. Collectively, these findings suggest a role for the ANXA1-FPR2 signaling pathway in attenuating the pathogenesis of periodontal disease by regulating localized inflammatory responses within periodontal tissues.

Remineralization is an essential interventional strategy for intercepting enamel white spot lesions (WSLs). Given the limitations of both natural and/or fluoride-mediated repair processes, there is a need to develop novel strategies for repairing enamel WSLs via a minimally invasive approach while restoring the unique ultrastructural integrity and functional properties. Inspired by the unique capability of high-intensity focused ultrasound (HIFU) in facilitating the crystallization process, we propose a novel strategy of employing HIFU for in vitro repair of WSLs through synergizing the crystallization process required for hydroxyapatite (HAP) formation from its precursor (calcium phosphate ion clusters; CPICs). Following CPIC formulation and characterization including the resultant amorphous calcium phosphate (ACP), the effect of HIFU on the ACP-to-HAP transition on the amorphous substrate was investigated using transmission electron microscopy and high-resolution transmission electron microscopy, selected area electron diffraction, and X-ray diffraction (XRD). The results showed profound amorphous-to-crystalline phase transition, within 5- to 30-min HIFU exposure, whereas the long axis of the resultant HAP corresponded with the (002) plane, and a lattice spacing of 0.34 nm indicated a preferred c-axis growth direction consistent with the orientation of natural enamel crystallites. For enamel repair, artificial WSLs were created on enamel specimens and then subjected to CPICs, followed by HIFU exposure for 2.5, 5, or 10 min. Scanning electron and atomic force microscopies revealed the decreased surface roughness and the gradual obliteration in the WSL porous structure with continuous linear coaxial arrangement of HAP crystallites filling the prismatic/interprismatic gaps closely resembling sound enamel specifically with 5-min HIFU exposure. Enamel WSL ultrastructural repair was further confirmed from XRD and Raman spectral analyses with the associated regaining of mineral density and nanomechanical properties as reflected from micro-computed tomography (CT) and nanoindentation results, respectively. Micro-CT further validated the subsurface remineralization of WSLs with HIFU exposure. Within the same exposure parameters, HIFU exhibited a potent antibiofilm effect against Streptococcus mutans. This study introduced a new approach for remineralizing enamel WSLs through the potent synergy between HIFU and CPICs.

While Lactiplantibacillus plantarum has shown promise against cariogenic pathogens, its in vivo effects on caries prevention remain unexplored. This study used a rat model to investigate the effect of L. plantarum early-life oral inoculation on oral and gut microbiomes, host immune responses, and serum metabolites. Forty 14-day Sprague-Dawley rat pups were randomly allocated into 5 groups: (1) blank control, (2) L. plantarum colonization alone, (3) Streptococcus mutans and Candida albicans co-colonization, (4) L. plantarum precolonization before S. mutans and C. albicans exposure, and (5) 2-wk treatment of L. plantarum after S. mutans and C. albicans exposure. Dynamic colonization of L. plantarum, S. mutans, and C. albicans in saliva and plaque was assessed using a culture-dependent method. Saliva, plaque, and fecal microbiomes were assessed using 16S ribosomal RNA gene sequencing. Caries scoring was performed using Keyes' scoring system and microcomputed tomography. Serum metabolite and immune markers were assessed through liquid chromatography tandem mass spectrometry untargeted metabolomics and multiplex immune profiling. We found that 3-d L. plantarum inoculation established stable L. plantarum colonization in the oral cavity of young rats. Inoculation timing of L. plantarum was critical for caries prevention. L. plantarum precolonization significantly reduced caries lesions compared with the S. mutans and C. albicans group, whereas 2 wk of postexposure treatment did not demonstrate a protective effect. L. plantarum precolonization led to distinct microbial shifts in saliva, plaque, and gut microbiomes, with an increased abundance of beneficial bacteria, such as Streptococcus azizii, Bifidobacterium animalis, Faecalibaculum rodentium, and Allobaculum stercoricanis, and a decrease in S. mutans. L. plantarum preinoculation also influenced metabolic profiles, with 1 metabolite upregulated and 24 downregulated, although immune marker differences were minimal. In conclusion, L. plantarum oral colonization before host exposure to oral cariogenic pathogens effectively reduced caries and modulated the profile of oral and gut microbiomes and serum metabolic profile.

Triggering receptor expressed on myeloid cells 2 (TREM2) is an immune receptor that plays a vital role in innate immune responses. This study aims to investigate the effect of TREM2 on synovial barrier homeostasis and synovitis during temporomandibular joint osteoarthritis (TMJOA). The expression level of TREM2 is decreased in the synovium of both patients with TMJOA and a mouse model of TMJOA, accompanied by synovial barrier breakdown. TREM2 overexpression inhibits the macrophage inflammatory response ex vivo and relieves synovial inflammation, cartilage degeneration, and synovial barrier destruction in monosodium iodoacetate-induced TMJOA mice. RNA-seq analysis reveals that Siglec1 serves as a downstream signal that is downregulated after TREM2 activation. Further in vivo and in vitro experiments demonstrate that rhSiglec1 treatment promotes the synthesis and release of inflammatory cytokines, such as interleukin-6 and RANTES, in macrophages and reverses the alleviation effect of TREM2 activation on TMJOA synovial barrier disorders, synovial inflammation, cartilage degradation, and bone destruction. Overall, this study verifies that TREM2 activation alleviates TMJOA pathology by maintaining synovial barrier homeostasis and inhibiting synovial inflammation. These findings provide new insight into the mechanism of TREM2 in the pathogenesis of TMJOA.

Palmitoylation is recognized as a prevalent posttranslational modification of proteins, which is highlighted in recent studies as a key player in regulating protein stability, subcellular localization, membrane transport, and other cellular biological processes. However, its role in peri-implant osteogenesis under type 2 diabetes mellitus (T2DM) remains unclear. During this study, the in vitro high-glucose model based on MC3T3-E1 cells demonstrated that a high-glucose environment in vitro markedly inhibited osteoblasts proliferation and osteogenesis; meanwhile, ZDHHC9 emerged as a significantly upregulated protein. Then, Zdhhc9 knockdown improved the dysfunction of osteoblasts and peri-implant osteogenesis of T2DM mice. In addition, co-immunoprecipitation and fluorescence co-localization analysis revealed an interaction between ZDHHC9 and cyclic guanosine monophosphate (GMP)-dependent protein kinase G 1 (PKG1), and silencing of Prkg1 prevented the improvement in osteoblasts with Zdhhc9 knockdown. Furthermore, we verified that Zdhhc9 knockdown and Prkg1 silencing altered the distance between the endoplasmic reticulum and mitochondria and the expression of mitochondria-associated endoplasmic reticulum membranes (MAMs)-related proteins in osteoblasts. Collectively, our data show that ZDHHC9 could regulate MAMs through palmitoylation of PKG1 to induce osteoblast dysfunction in T2DM. ZDHHC9 might become a novel therapeutic target for peri-implant osteogenesis in diabetes patients.

Development of dentition is a commonly studied process as a representative of the development of ectodermal derivates. A key step is the formation of a signaling center called the enamel knot (EK), which organizes tooth crown formation. In the mouse lower jaw, the anterior part of the tooth-forming region undergoes a series of complex events before the first molar primary EK can form more posteriorly and the tooth can progress through the cap stage. Although much is known about the molecular factors involved in tooth development, disentangling their specific roles is difficult. In this study, we circumvented this problem by isolating the posterior part of the tooth-forming region at embryonic day 13.5 and cultivating it in vitro. By treating them with molecules activating or inhibiting Sonic hedgehog (Shh) and fibroblast growth factor (Fgf) pathways, we demonstrate that Shh plays the role of an inhibitor of EK formation, and we suggest that the FGF pathways may have both positive and negative roles, as seen in hair. By RNA-sequencing of the cultivated isolates after 0, 16, or 24 h in vitro, respectively, we screened for genes whose expression varies with EK and cap formation and pointed to Cdkn2b and Sema3b as 2 promising candidates in this process.

Orthodontic root resorption (ORR) is a common yet significant complication of orthodontic treatment, largely driven by interactions between periodontal ligament cells (PDLCs) and M1 macrophages. Despite the clinical relevance of ORR, the role of mechanosensitive ion channels in PDLC-mediated ORR and the underlying mechanisms regulating inflammatory cell recruitment remain poorly understood. Here, we identified PIEZO1 as a critical mechanosensitive ion channel that modulates monocyte recruitment and ORR. Using in vivo models treated with the PIEZO1 activator Yoda1 and inhibitor AAV-shPiezo1, we demonstrated that PIEZO1 activation promoted the recruitment of Ly6C^hi inflammatory monocytes and exacerbated ORR. In contrast, PIEZO1 inhibition attenuated ORR and the accumulation of M1 macrophages. Mechanistically, PIEZO1 positively regulated the C-X-C motif chemokine 12 (CXCL12) and its receptor, C-X-C chemokine receptor type 4 (CXCR4). Blocking the CXCL12/CXCR4 axis using the CXCR4 antagonist AMD3100 significantly alleviated ORR, reversed M1 macrophage accumulation, and mitigated the recruitment of CD11b⁺Ly6C^hi monocytes. Transwell migration assays with application of the PIEZO1 activator Yoda1 and PIEZO1 inhibitor GsMTX4 consistently confirmed the PIEZO1/CXCL12/CXCR4 axis as a key driver of PDLC-monocyte interactions. Notably, PIEZO1 overactivation was linked to excessive IL-6 production, and IL-6 deficiency inhibited the activation of PIEZO1 induced by Yoda1, leading to attenuation of ORR, M1 macrophage accumulation, and CXCL12/CXCR4 axis activation. Collectively, these findings reveal PIEZO1 in PDLCs as a pivotal modulator of inflammatory monocyte recruitment via the CXCL12/CXCR4 axis in ORR, with IL-6 playing an essential role in PIEZO1 activation. This study provides new insights into the molecular crosstalk between PDLCs and macrophages, offering potential therapeutic targets for mitigating ORR in orthodontic patients.

It is common to encounter discrepancies between in vitro and in vivo studies, particularly when assessing the antibiofilm efficacy of dental materials. Typically, dental materials are tested in a closed system where fresh nutrients are not replenished, the test conditions are static, and the same planktonic bacteria persist. However, real environments are characterized by the continuous supply of fresh nutrients, dynamic saliva flow, and the periodic removal of planktonic bacteria through swallowing. To address these differences, we used an open system approach using microfluidic chips that simulate the nutrient and fluid flow conditions of the mouth. This setup enables the spatiotemporal development of biofilms, facilitates real-time observation, and provides deeper insights into the biofilm formation and removal processes. Photocatalytic dental materials are particularly suitable for use with microfluidic chips, as these devices allow real-time tracking of biofilm dynamics, both with and without light exposure. Nitrogen-doped titanium dioxide effectively produces reactive oxygen species (ROS) under visible light conditions, even when embedded in a resin matrix. These ROS have been shown to inhibit Enterococcus faecalis biofilms. The evaluation of the photocatalytic effects of dental materials using microfluidic chips showed that both new and established biofilms were disrupted by ROS production. ROS weakens the interface between the biofilm and dental material, allowing the biofilm mass to be removed by fluid flow. Furthermore, the open system provided by microfluidic chips demonstrated higher accuracy in evaluating antibiofilm efficiency than the conventional system did. Thus, the developed microfluidic chip is a novel and promising tool for assessing antibiofilm properties, with potential applications in various fields.

Pulpitis is characterized by inflammation within dental pulp tissue, primarily triggered by bacterial infection. Hypoxia-inducible factor-1α (HIF-1α), a key transcriptional regulator, is stabilized under the hypoxic conditions associated with pulpitis. This review examines the roles and molecular mechanisms of HIF-1α in the pathogenesis and progression of pulpitis. Hypoxia in pulpitis prevents the degradation of HIF-1α, leading to its elevated expression. Furthermore, lipopolysaccharide from invading bacteria upregulates HIF-1α transcription through nuclear factor kappa B and mitogen-activated protein kinase pathways. HIF-1α regulates immunity and pulp remodeling in a stage-dependent manner by controlling various cytokines. During the inflammation stage, HIF-1α promotes recruitment of neutrophils and enhances their bactericidal effects by facilitating neutrophil extracellular trap release and M1 macrophage polarization. Concurrently, HIF-1α contributes to programmed cell death by increasing mitophagy. In the proliferation stage, HIF-1α stimulates immune responses involving T cells and dendritic cells. In the remodeling stage, HIF-1α supports angiogenesis and pulp-dentin regeneration. However, excessive pulpitis-induced hypoxia may disrupt vascular dynamics within the pulp chamber. This disruption highlights a critical threshold for HIF-1α, beyond which its effects might accelerate pulp necrosis. Overall, HIF-1α plays a central role in regulating immunity and tissue remodeling during pulpitis. A comprehensive understanding of the physiological and pathological roles of HIF-1α is essential for the advancement of effective strategies to manage irreversible pulpitis.

Extracellular vesicles (EVs) are lipid-enclosed particles released from cells, containing lipids, DNA, RNA, metabolites, and cytosolic and cell surface proteins. EVs support intercellular communication and orchestrate organogenesis by transferring bioactive molecules in between cells. Mesenchymal stem cells are known to produce EVs, which exhibit immunomodulatory and regenerative capabilities in many target organs, including the salivary glands (SGs). Since cell-based therapies still pose challenges (e.g., donor variability, limited hemocompatibility, and safety), specific EVs may constitute a therapeutic alternative for SG diseases. New EV guidelines (MISEV2023) have recently been updated and reported by our consortium to consolidate the principles of EV biology and expand the boundaries toward innovative therapies. These guidelines provide valuable guidance for researchers to consistently assess the effectiveness of mesenchymal stem cell-derived EV cargo cues, such as microRNA, proteins, and other molecules, to target SG diseases. This review provides a narrative synthesis of preclinical studies on EVs by highlighting EV mechanisms and their potential therapeutic applications for SG diseases, such as radiotherapy-induced SG hypofunction and Sjögren's syndrome, as well as inflammatory and aging-related SG conditions. Additionally, we highlight key areas of the MISEV2023 guidelines that will support future EV-based therapies in SG research. This review adhered to PRESS guidelines (Peer Review of Electronic Search Strategies) and utilized established databases, including Medline/PubMed, Embase, Web of Science, and Scopus, alongside machine learning tools for sorting the most impactful EV studies for SG diseases.