RNA-seq Analysis of Peri-Implant Tissue Shows Differences in Immune, Notch, Wnt, and Angiogenesis Pathways in Aged Versus Young Mice

JAG1/Notch Pathway Inhibition Induces Ferroptosis and Promotes Cataractogenesis

Cataracts remain the leading cause of visual impairment worldwide, yet the underlying molecular mechanisms, particularly in age-related cataracts (ARCs), are not fully understood. The Notch signaling pathway, known for its critical role in various degenerative diseases, may also contribute to ARC pathogenesis, although its specific involvement is unclear. This study investigates the role of Notch signaling in regulating ferroptosis in lens epithelial cells (LECs) and its impact on ARC progression. RNA sequencing of anterior lens capsule samples from ARC patients revealed a significant downregulation of Notch signaling, coupled with an upregulation of ferroptosis-related genes. Notch1 expression decreased, while ferroptosis markers increased in an age-dependent manner. In vitro, upregulation of Notch signaling alleviated ferroptosis by decreasing ferritin heavy chain 1 (FTH1) and p53 levels while enhancing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPX4), and solute carrier family 7 member 11 (SLC7A11). Conversely, inhibition of Notch signaling exacerbated ferroptosis, as evidenced by reduced Nrf2, GPX4, and SLC7A11 expression. These findings suggest that downregulation of Notch signaling promotes ferroptosis in LECs by impairing the Nrf2/GPX4 antioxidant pathway, thereby contributing to ARC development. This study offers new insights into ARC pathogenesis and highlights the Notch signaling pathway as a potential therapeutic target for preventing or mitigating ARC progression.

USP7 Inhibition Promotes Early Osseointegration in Senile Osteoporotic Mice

Although elderly osteoporotic patients have similar implant survival rates compared with those of normal individuals, they require longer healing periods to achieve proper osseointegration. This may be related to chronic inflammatory responses and impaired stem cell repair functions in the osteoporotic bone microenvironment. Recently, the deubiquitinating enzyme, ubiquitin-specific peptidase 7 (USP7), was found to regulate the macrophage immune response and modulate stem cell osteogenic differentiation. The selective inhibitor of USP7, P5091, has also been found to promote bone repair and homeostasis in osteoporotic conditions. However, the roles of USP7 and P5091 in osteoimmunology and dental implant osseointegration under senile osteoporotic conditions remain unclear. In this study, USP7 depletion and P5091 were shown to inhibit inflammation in senescent bone marrow-derived macrophages (BMDMs) and promote osteogenic differentiation in aged bone marrow mesenchymal stromal cells (BMSCs). Furthermore, mRNA-Seq revealed that USP7 depletion could enhance efferocytosis in senescent BMDMs through the EPSIN1/low-density lipoprotein receptor-related protein 1 (LRP1) pathway and selectively induce apoptosis (senolysis) in aged BMSCs. In senile osteoporotic mice, we found that the osseointegration period was prolonged compared with young mice, and P5091 promoted the early stage of osseointegration, which may be related to macrophage efferocytosis around the implant. Collectively, this study suggests that USP7 inhibition may accelerate the osseointegration process in senile osteoporotic conditions by promoting macrophage efferocytosis and aged BMSCs apoptosis. This has implications for understanding the cellular interactions and signaling mechanisms in the peri-implant bone microenvironment under osteoporotic conditions. It may also provide clinical significance in developing new therapies to enhance osseointegration quality and shorten the edentulous period in elderly osteoporotic patients.

Effects of antiseptic irrigation solutions on osseointegration in a cementless tibial implantation mouse model

Despite the success of standard antiseptic irrigation solutions in reducing periprosthetic joint infection (PJI) rates, there is still a need for more effective solutions. Synergistic use of povidone-iodine (PI) and hydrogen peroxide (H2O2) has shown promising results; however, the optimal solution concentration balancing bactericidal activity and osseointegration remains unknown. This study aims to evaluate the impact of these antiseptic irrigation solutions on osseointegration and the bone-implant interface strength in vivo. Forty C57BL/6 mice underwent bilateral tibial implantation surgery and were randomly allocated into three groups receiving 0.3% PI, 10% PI mixed with 3% H2O2, or saline as irrigation solutions intraoperatively. Assessments were performed on postoperative Days 1 and 28, including plain radiographs, microcomputed tomography (microCT) evaluation, histological analysis, immunohistochemistry, and biomechanical pull-out testing. No wound complications were observed. MicroCT scans revealed no differences in peri-implant trabecular bone parameters. Biomechanical pull-out testing showed no differences in the bone-implant interface strength across groups. Histological analysis indicated no differences in bone and bone marrow percentage areas among treatment groups. Immunohistochemical analysis demonstrated no differences among groups in peri-implant osteocalcin, osterix, or endomucin-positive cells. In conclusion, using either antiseptic irrigation solution showed no differences in osseointegration parameters compared to the control group, demonstrating safety and the absence of toxicity. CLINICAL RELEVANCE: Dilute 0.3% povidone-iodine and a 1:1 combination of 10% povidone-iodine mixed with 3% hydrogen peroxide can be safely used during primary and revision total joint arthroplasty without compromising osseointegration or causing wound complications.

USP26 Combats Age-Related Declines in Self-Renewal and Multipotent Differentiation of BMSC by Maintaining Mitochondrial Homeostasis

Age-related declines in self-renewal and multipotency of bone marrow mesenchymal stem cells (BMSCs) limit their applications in tissue engineering and clinical therapy. Thus, understanding the mechanisms behind BMSC senescence is crucial for maintaining the rejuvenation and multipotent differentiation capabilities of BMSCs. This study reveals that impaired USP26 expression in BMSCs leads to mitochondrial dysfunction, ultimately resulting in aging and age-related declines in the self-renewal and multipotency of BMSCs. Specifically, decreased USP26 expression results in decreased protein levels of Sirtuin 2 due to its ubiquitination degradation, which leads to mitochondrial dysfunction in BMSCs and ultimately resulting in aging and age-related declines in self-renewal and multilineage differentiation potentials. Additionally, decreased USP26 expression in aging BMSCs is a result of dampened hypoxia-inducible factor 1α (HIF-1α) expression. HIF-1α facilitates USP26 transcriptional expression by increasing USP26 promoter activity through binding to the -191 - -198 bp and -262 - -269 bp regions on the USP26 promoter. Therefore, the identification of USP26 as being correlated with aging and age-related declines in self-renewal and multipotency of BMSCs, along with understanding its expression and action mechanisms, suggests that USP26 represents a novel therapeutic target for combating aging and age-related declines in the self-renewal and multipotent differentiation of BMSCs.

A translational murine model of aseptic loosening with osseointegration failure

An in vivo animal model of a weight-bearing intra-articular implant is crucial to the study of implant osseointegration and aseptic loosening caused by osseointegration failure. Osseointegration, defined as a direct structural and functional attachment between living bone tissue and the surface of a load-carrying implant, is essential for implant stability and considered a prerequisite for the long-term clinical success of implants in total joint arthroplasty. Compared to large animal models, murine models offer extensive genetic tools for tracing cell differentiation and proliferation. The 18- to 22-week-old C57BL/6J background mice underwent either press-fitted or loose implantation of a titanium implant, achieving osseointegration or fibrous integration. A protocol was developed for both versions of the procedure, including a description of the relevant anatomy. Samples were subjected to microcomputed tomography and underwent biomechanical testing to access osseointegration. Lastly, samples were fixed and embedded for histological evaluation. The absence of mineralized tissue and weakened maximum pull-out force in loose implantation samples indicated that these implants were less mechanically stable compared to the control at 4 weeks postoperation. Histological analysis demonstrated extensive fibrotic tissue in the peri-implant area of loose implantation samples and excellent implant osseointegration in press-fitted samples at 4 weeks. Both mechanically stable and unstable hemiarthroplasty models with either osseous ingrowth or a robust periprosthetic fibrosis were achieved in mice. We hope that this model can help address current limitations for in vivo study of aseptic loosening and lead to necessary translational benefits.

The impact of antimicrobial photodynamic therapy on pain and oral health-related quality of life: A literature review

Antimicrobial photodynamic therapy (aPDT) is a non-invasive approach used for microbial decontamination, and it can also be beneficial as an adjunctive strategy for oral infections. The success of treatment in the long term is increasingly recognized to be influenced by patient's perception of the disease and its improvement. Recently, aPDT has been suggested as a dual approach to tissue repair, pain relief, and enhancement of oral health-related quality of life (OHRQoL). The first pathway involves the antimicrobial and anti-inflammatory effects of aPDT. It not only eliminates microorganisms but also helps regulate the immune response and reduce inflammation, leading to a faster and more effective healing process. This, in turn, provides relief from pain and associated symptoms, aiding in the management of treatment complications. The second pathway involves aPDT's ability to modulate nociception and alleviate pain. aPDT induces analgesia by releasing neurotransmitters such as β-endorphin, serotonin, and acetylcholinesterase. It also interacts with mitochondria through photoreceptors, initiating intracellular processes that alleviate pain. Furthermore, the therapy inhibits nerve fibers, reducing nerve impulse conduction and altering the pain threshold. Considering that the impact on patients' pain and OHRQoL is an important aspect of the decision-making process, this study aimed to review patient-based outcome measures during aPDT and assess its effects on pain and OHRQoL in patients. Understanding these factors will contribute to a better assessment of the overall benefits and effectiveness of aPDT as a treatment option for oral infections.

Application of photosensitive dental materials as a novel antimicrobial option in dentistry: A literature review

The formation of dental plaque is well-known for its role in causing various oral infections, such as tooth decay, inflammation of the dental pulp, gum disease, and infections of the oral mucosa like peri-implantitis and denture stomatitis. These infections primarily affect the local area of the mouth, but if not treated, they can potentially lead to life-threatening conditions. Traditional methods of mechanical and chemical antimicrobial treatment have limitations in fully eliminating microorganisms and preventing the formation of biofilms. Additionally, these methods can contribute to the development of drug-resistant microorganisms and disrupt the natural balance of oral bacteria. Antimicrobial photodynamic therapy (aPDT) is a technique that utilizes low-power lasers with specific wavelengths in combination with a photosensitizing agent called photosensitizer to kill microorganisms. By inducing damage through reactive oxygen species (ROS), aPDT offers a new approach to addressing dental plaque and associated microbial biofilms, aiming to improve oral health outcomes. Recently, photosensitizers have been incorporated into dental materials to create photosensitive dental materials. This article aimed to review the use of photosensitive dental materials for aPDT as an innovative antimicrobial option in dentistry, with the goal of enhancing oral health.

Antimicrobial photodynamic therapy for managing the peri-implant mucositis and peri-implantitis: A systematic review of randomized clinical trials

BACKGROUND

The presence of peri‑implant inflammation including peri‑implant mucositis and peri‑implantitis, is a crucial factor that impacts the long-term stability and success of dental implants. This review aimed to evaluate the safety and effectiveness of antimicrobial photodynamic therapy (aPDT) as an adjuvant therapy option for managing peri‑implant mucositis and peri‑implantitis.

METHODS

We systematically searched the PubMed/MEDLINE, Cochrane Library, Scopus, and Google Scholar databases (no time limitation). The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the quality of the studies was assessed using the Cochrane Collaboration tool.

RESULTS

Of 322 eligible articles, 14 studies were included in this review. The heterogeneity and poor quality of the articles reviewed prevented a meta-analysis. The reviewed articles used a light source (60 s, 1 session) with a wavelength of 635 to 810 nm for optimal tissue penetration. These studies showed improved clinical parameters such as probing depth, bleeding on probing (BOP), and plaque index after aPDT treatment. However, in smokers, BOP increased after aPDT. Compared to conventional therapy, aPDT had a longer-term antimicrobial effect and reduced periopathogens like Porphyromonas gingivalis, as well as inflammatory factors such as Interleukin (IL)-1β, IL-6, and Tumor necrosis factor alpha (TNF-α). No undesired side effects were reported in the studies.

CONCLUSION

Although the reviewed articles had limitations, aPDT showed effectiveness in improving peri‑implant mucositis and peri‑implantitis. It is recommended as an adjunctive strategy for managing peri‑implant diseases, but further high-quality research is needed for efficacy and long-term outcomes.

Influence of Scaffold Microarchitecture on Angiogenesis and Regulation of Cell Differentiation during the Early Phase of Bone Healing: A Transcriptomics and Histological Analysis

The early phase of bone healing is a complex and poorly understood process. With additive manufacturing, we can generate a specific and customizable library of bone substitutes to explore this phase. In this study, we produced tricalcium phosphate-based scaffolds with microarchitectures composed of filaments of 0.50 mm in diameter, named Fil050G, and 1.25 mm named Fil125G, respectively. The implants were removed after only 10 days in vivo followed by RNA sequencing (RNAseq) and histological analysis. RNAseq results revealed upregulation of adaptive immune response, regulation of cell adhesion, and cell migration-related genes in both of our two constructs. However, significant overexpression of genes linked to angiogenesis, regulation of cell differentiation, ossification, and bone development was observed solely in Fil050G scaffolds. Moreover, quantitative immunohistochemistry of structures positive for laminin revealed a significantly higher number of blood vessels in Fil050G samples. Furthermore, µCT detected a higher amount of mineralized tissue in Fil050G samples suggesting a superior osteoconductive potential. Hence, different filament diameters and distances in bone substitutes significantly influence angiogenesis and regulation of cell differentiation involved in the early phase of bone regeneration, which precedes osteoconductivity and bony bridging seen in later phases and as consequence, impacts the overall clinical outcome.

Anti-biofilm and bystander effects of antimicrobial photo-sonodynamic therapy against polymicrobial periopathogenic biofilms formed on coated orthodontic mini-screws with zinc oxide nanoparticles

BACKGROUND

The present study evaluated the anti-biofilm and bystander effects of antimicrobial photo-sonodynamic therapy (aPSDT) on the polymicrobial periopathogenic biofilms formed on mini-screws coated with zinc oxide nanoparticles (ZnONPs).

MATERIALS AND METHODS

Thirty orthodontic identical mini-screws were divided into 6 groups (n = 5) as follows: 1. negative control: uncoated mini-screw + phosphate-buffered saline (PBS), 2. positive control: uncoated mini-screw + 0.2% CHX, 3. coating control: coated mini-screw + PBS, 4. antimicrobial photodynamic therapy (aPDT): coated mini-screw+light emitting diode (LED), 5. Antimicrobial sonodynamic therapy (aSDT): coated mini-screw+ultrasound waves, and 6. aPSDT: coated mini-screw+LED+ultrasound waves. Electrostatic spray-assisted vapor deposition was employed to coat ZnONPs on titanium mini-screws. The biofilm inhibition test was used to assess the anti-biofilm efficacy against polymicrobial periopathogenic biofilms including Porphyromonas gingivitis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans, and the results were shown as the percent reduction of Log₁₀ colony-forming unit (CFU)/mL. Following each treatment, the gene expression levels of TNF-α, IL-1β, and IL-6 were evaluated on human gingival fibroblast (HGF) cells via quantitative real-time polymerase chain reaction (qRT-PCR) to reveal the bystander effects of aPSDT on HGF cells.

RESULTS

A significant reduction in log₁₀ CFU/mL of periopathogens was observed in groups treated with aPDT, aSDT, aPSDT, and 0.2% CHX up to 6.81, 6.63, 5.02, and 4.83 log, respectively, when compared with control groups (P<0.05). 0.2% CHX and aPSDT groups demonstrated significantly higher capacity in eliminating the periopathogen biofilm compared with other groups (P<0.05). The qRT-PCR showed that the expression level of inflammatory cytokines was significantly down regulated in aPDT, aSDT, and aPSDT groups (P<0.05).

CONCLUSION

It was found that the ZnONPs-mediated aPSDT could significantly reduce periopathogen biofilm as well as the expression level of inflammatory cytokines.

Topography-mediated immunomodulation in osseointegration; Ally or Enemy

Osteoimmunology is at full display during endosseous implant osseointegration. Bone formation, maintenance and resorption at the implant surface is a result of bidirectional and dynamic reciprocal communication between the bone and immune cells that extends beyond the well-defined osteoblast-osteoclast signaling. Implant surface topography informs adherent progenitor and immune cell function and their cross-talk to modulate the process of bone accrual. Integrating titanium surface engineering with the principles of immunology is utilized to harness the power of immune system to improve osseointegration in healthy and diseased microenvironments. This review summarizes current information regarding immune cell-titanium implant surface interactions and places these events in the context of surface-mediated immunomodulation and bone regeneration. A mechanistic approach is directed in demonstrating the central role of osteoimmunology in the process of osseointegration and exploring how regulation of immune cell function at the implant-bone interface may be used in future control of clinical therapies. The process of peri-implant bone loss is also informed by immunomodulation at the implant surface. How surface topography is exploited to prevent osteoclastogenesis is considered herein with respect to peri-implant inflammation, osteoclastic precursor-surface interactions, and the upstream/downstream effects of surface topography on immune and progenitor cell function.