Polarized M2 macrophages induced by glycosylated nano-hydroxyapatites activate bone regeneration in periodontitis therapy.

AIM: To investigate the association between periodontal macrophage polarization states and the alveolar bone levels, and to assess whether glycosylated nano-hydroxyapatites (GHANPs) could improve bone regeneration in periodontitis by inducing macrophage M2 polarization. MATERIALS AND METHODS: The change of macrophage polarization state in inflammatory periodontal tissues (with bone loss) was examined using clinical gingival samples. The relationship between macrophage phenotype and bone level in periodontal bone loss and repair was evaluated using a mouse periodontitis model. The effect of GHANPs on macrophage polarization was assessed by the in vitro model of lipopolysaccharide (LPS)-stimulated inflammation. The polarization-related markers were detected by immunofluorescence staining, real-time polymerase chain reaction and enzyme-linked immunosorbent assay analysis. The therapeutic effect of GHANPs on alveolar bone loss was explored in experimental periodontitis by histological staining and micro-CT analysis. RESULTS: A lower macrophage M2/M1 ratio was observed in periodontitis-affected human gingival tissues. The results of animal experiments demonstrated a positive correlation between a lower Arg-1/iNOS ratio and accelerated alveolar bone loss; also, the proportion of Arg-1-positive macrophages increased during bone repair and regeneration. The administration of GHANPs partially restored M2 macrophage polarization after LPS stimulation. GHANPs increased alveolar bone repair and regeneration in experimental periodontitis induced by ligation, potentially related to their macrophage M2 transition regulation. CONCLUSIONS: The findings of this study indicate that the induction of macrophage M2 polarization can be considered a viable approach for enhancing inflammatory bone repair. Additionally, GHANPs show potential in the clinical treatment of periodontitis.

Nanochemistry of gold: from surface engineering to dental healthcare applications.

Advancements in nanochemistry have led to the development of engineered gold nanostructures (GNSs) with remarkable potential for a variety of dental healthcare applications. These innovative nanomaterials offer unique properties and functionalities that can significantly improve dental diagnostics, treatment, and overall oral healthcare applications. This review provides an overview of the latest advancements in the design, synthesis, and application of GNSs for dental healthcare applications. Engineered GNSs have emerged as versatile tools, demonstrating immense potential across different aspects of dentistry, including enhanced imaging and diagnosis, prevention, bioactive coatings, and targeted treatment of oral diseases. Key highlights encompass the precise control over GNSs' size, crystal structure, shape, and surface functionalization, enabling their integration into sensing, imaging diagnostics, drug delivery systems, and regenerative therapies. GNSs, with their exceptional biocompatibility and antimicrobial properties, have demonstrated efficacy in combating dental caries, periodontitis, peri-implantitis, and oral mucosal diseases. Additionally, they show great promise in the development of advanced sensing techniques for early diagnosis, such as nanobiosensor technology, while their role in targeted drug delivery, photothermal therapy, and immunomodulatory approaches has opened new avenues for oral cancer therapy. Challenges including long-term toxicity, biosafety, immune recognition, and personalized treatment are under rigorous investigation. As research at the intersection of nanotechnology and dentistry continues to thrive, this review highlights the transformative potential of engineered GNSs in revolutionizing dental healthcare, offering accurate, personalized, and minimally invasive solutions to address the oral health challenges of the modern era.

Detection and treatment of biofilm-induced periodontitis by histidine-doped FeSN nanozyme with ultra-high peroxidase-like activity.

Pathogenic biofilm induced oral diseases have posed a significant treat to human health, such as periodontitis resulting from the formation of bacterial biofilm on teeth and gums. The traditional treatment methods such as mechanical debridement and antibiotic therapy encounter the poor therapeutic effect. Recently, numerous nanozymes with excellent antibacterial effect have been widely used in the treatment of oral diseases. In this study, a novel iron-based nanozyme (FeSN) generated by histidine-doped FeS2 with high peroxidase-like (POD-like) activity was designed for the oral biofilm removal and treatment of periodontitis. FeSN exhibited an extremely high POD-like activity, and enzymatic reaction kinetics and theoretical calculations had demonstrated its catalytic efficiency to be approximately 30 times than that of FeS2. The antibacterial experiments showed that FeSN had robust antibacterial activity against Fusobacterium nucleatum in the presence of H2O2, causing a reduction in the levels of glutathione reductase and ATP in bacterial cells, while increasing the level of oxidase coenzyme. The ultrahigh POD-like activity of FeSN allowed for easy detection of pathogenic biofilms and promoted the breakdown of biofilm structure. Furthermore, FeSN demonstrated excellent biocompatibility and low cytotoxicity to human fibroblast cells. In a rat model of periodontitis, FeSN exhibited significant therapeutic effects by reducing the extent of biofilm formation, inflammation, and alveolar bone loss. Taken together, our results suggested that FeSN, generated by self-assembly of two amino acids, represented a promising approach for biofilm removal and periodontitis treatment. This method has the potential to overcome the limitations of current treatments and provide an effective alternative for periodontitis treatment.

Bio-inspired glycosylated nano-hydroxyapatites enhance endogenous bone regeneration by modulating macrophage M2 polarization.

A macrophage-associated immune response is vital in bone regeneration. Mannose receptor (MR), a macrophage pattern-recognition receptor, is crucial for the maintenance of immune homeostasis. Here, we designed MR-targeted glycosylated nano-hydroxyapatites (GHANPs) to reprogram macrophages into polarized M2s, promoting bone regeneration by improving the osteoimmune microenvironment. The prepared GHANPs induced macrophage M2 polarization, which then promoted osteoblastic differentiation of stem cells. Further, the mechanistic study showed that GHANPs might influence macrophage polarization by modulating cell metabolism, including enhancing mitochondrial oxidative phosphorylation and activating autophagy. Finally, a rat cranial defect model was used to verify the effect of GHANPs on endogenous bone regeneration in vivo, revealing that GHANPs promoted bone regeneration within the defect and increased the ratio of M2/M1 macrophages in early bone repair. Our results indicate that the MR-targeted macrophage M2 polarization strategy is promising in endogenous bone regeneration. STATEMENT OF SIGNIFICANCE: Macrophage is a pivotal immunity component for bone regeneration. A switch to M2 macrophage has been considered to contribute to osteogenesis. For inducing macrophage M2 polarization, an effective strategy to overcome off-target effects and insufficient specificity is a critical challenge. The mannose receptor on the surface of macrophages has been involved in regulating macrophage directional polarization. The glucomannan presented on the nano-hydroxyapatite rods acts as ligands targeting macrophage mannose receptors to promote their M2 polarization, improving the immunomicroenvironment and achieving bone regeneration. This approach has the advantage of easy preparation, specific regulation, and safety.

Periodontitis salivary microbiota exacerbates nonalcoholic fatty liver disease in high-fat diet-induced obese mice.

Periodontitis may aggravate the development of nonalcoholic fatty liver disease (NAFLD); however, the precise mechanism is unknown. In this study, salivary microbiota collected from patients with periodontitis was transferred intragastrically to obese mice induced by high-fat diet. Microbiomics and metabolomics analysis were performed to assess the influence of periodontitis salivary microbiota on gut microbiome and liver metabolism. Periodontitis salivary microbiota altered gut microbiota composition and exacerbated intestinal barrier dysfunction in obese mice. Subsequently, the bacterial lipopolysaccharide transported to liver may activate the toll-like receptor 4 signaling and cause the release of pro-inflammatory factors. Moreover, the tryptophan-kynurenine-AhR signal axis was upregulated in liver, which may be related to aggravated hepatic steatosis and glucolipid metabolism dysregulation during NAFLD development. This study indicated that in the context of obesity, periodontitis salivary microbiota may aggravate the pathological progression of NAFLD, in which the tryptophan-AhR pathway may play a key role.

Rapid capture and killing of bacteria by lyophilized nFeS-Hydrogel for improved healing of infected wounds.

Due to their antibacterial activity, sulfur-containing nanomaterials are increasingly being developed into nanodrugs against bacterial infection. Nano iron sulfide (nFeS) is a new nanomaterial that can convert organic sulfur into inorganic sulfur, which has excellent antibacterial activity. However, the inorganic sulfur produced by nFeS can easily change its form or volatilize in aqueous solution, which may affect the efficacy of nFeS. We propose a new strategy to encapsulate nFeS in a hydrogel to preserve inorganic sulfides, and the macroporous structure of the hydrogel can capture bacteria to increase their interaction with nFeS. The in-depth characterization conducted in this study demonstrate that the water swelling characteristics of the lyophilized nFeS-Hydrogel and the ability to effectively maintain the antibacterial active ingredients in nFeS results in more effective killing of harmful bacteria than pure nFeS, while also prolonging the shelf life of antibacterial activity. We discovered that bacteria exhibit a unique mode of cell death when nFeS contained in hydrogels interacts with the cells by producing hydrogen polysulfanes, which increased intracellular ROS levels and reduced GSH levels. Furthermore, the nFeS-Hydrogel was found to reduce inflammation and exhibited excellent biocompatibility. Accordingly, the nFeS-Hydrogel has great application prospects as a fast excipient for clearing infection, reducing inflammation, and accelerating wound healing.

Antibiofilm activity of ultra-small gold nanoclusters against Fusobacterium nucleatum in dental plaque biofilms.

Pathogenic dental plaque biofilms are universal and harmful, which can result in oral infections and systemic diseases. Many conventional therapeutic methods have proven insufficient or ineffective against plaque biofilms. Therefore, new strategies are urgently needed. Fusobacterium nucleatum (F. nucleatum), a periodontal pathogen associated with a variety of oral and systemic diseases, is thought to be central to the development and structure of dental plaques. Here, ultra-small gold nanoclusters (AuNCs) were prepared. They exhibited potent antibacterial activity against F. nucleatum through enhanced destruction of bacterial membranes and generation of reactive oxygen species. Furthermore, due to their excellent penetration, the AuNCs could inhibit biofilm formation and destroy mature biofilms in vitro. Their antibiofilm efficacy was further confirmed in a mouse model, where they reduced biofilm accumulation and ameliorated inflammation. Meanwhile, the disruption of oral and gut microbiota caused by colonization of oral F. nucleatum could be partially restored through AuNCs treatment. Therefore, AuNCs could be considered as promising antibiofilm agents and have great potential in the clinical treatment of dental plaque.

Multifunctional fluorescent gold nanoclusters with enhanced aggregation-induced emissions (AIEs) and excellent antibacterial effect for bacterial imaging and wound healing.

To explore new alternatives to combat increasing risk of bacterial infection, in this work, a cationic antimicrobial peptide (HHC10) and glutathione (GSH) co-ligand protected ultra-small gold nanoclusters (Au NCs) was constructed by a simple one-pot method. The intrinsic luminescent property of GSH-protected Au NCs (AuxGSH) endowed enhanced aggregation-induced emissions (AIEs) of co-ligand-protected Au NCs (AuxGSH-HHC10), which exhibited a very strong orange luminescence. Based on the AIE effect, for one thing, AuxGSH could be applied to rapidly and selectively detect Gram-positive bacteria. For another, AuxGSH-HHC10 exhibited potential for multicolor imaging of both Gram-negative and Gram-positive bacteria. Besides, as-synthesized AuxGSH-HHC10 could act as potent nanoantibiotics against both Gram-negative and Gram-positive bacteria, which could not only avoid drug tolerance but also be effective toward drug-resistance bacteria. The antibacterial mechanism indicated that the synergetic effect of the generation of reactive oxygen species (ROS), binding with DNA, and broad-spectrum antibacterial activity of HHC10 led to the membrane damage, depolarization, and interference of biological function, thus enhancing the antibacterial effect. More importantly, such an Au NCs could realize excellent therapeutic outcomes for wound healing in vivo, and showed good biocompatibility and biosafety toward health tissues. The results will provide a great potential for the application of Au NCs for imaging-guided antibacterial platform.

Sustainable lignin and lignin-derived compounds as potential therapeutic agents for degenerative orthopaedic diseases: A systemic review.

Lignin, the most abundant natural and sustainable phenolic compound in biomass, has exhibited medicinal values due to its biological activities decided by physicochemical properties. Recently, the lignin and its derivatives (such as lignosulfonates and lignosulfonate) have been proven efficient in regulating cellular process and the extracellular microenvironment, which has been regarded as the key factor in disease progression. In orthopaedic diseases, especially the degenerative diseases represented by osteoarthritis and osteoporosis, excessive activated inflammation has been proven as a key stage in the pathological process. Due to the excellent biocompatibility, antibacterial and antioxidative activities of lignin and its derivatives, they have been applied to stimulate cells and restore the uncoupling bone remodeling in the degenerative orthopaedic diseases. However, there is a lack of a systemic review to state the current research actuality of lignin and lignin-derived compounds in treating degenerative orthopaedic diseases. Herein, we summarized the current application of lignin and lignin-derived compounds in orthopaedic diseases and proposed their possible therapeutic mechanism in treating degenerative orthopaedic diseases. It is hoped this work could guide the future preparation of lignin/lignin-derived drugs and implants as available therapeutic strategies for clinically degenerative orthopaedic diseases.

Periodontitis may induce gut microbiota dysbiosis via salivary microbiota.

The aim of this study was to identify whether periodontitis induces gut microbiota dysbiosis via invasion by salivary microbes. First, faecal and salivary samples were collected from periodontally healthy participants (PH group, n = 16) and patients with severe periodontitis (SP group, n = 21) and analysed by 16S ribosomal RNA sequencing. Significant differences were observed in both the faecal and salivary microbiota between the PH and SP groups. Notably, more saliva-sourced microbes were observed in the faecal samples of the SP group. Then, the remaining salivary microbes were transplanted into C57BL6/J mice (the C-PH group and the C-SP group), and it was found that the composition of the gut microbiota of the C-SP group was significantly different from that of the C-PH group, with Porphyromonadaceae and Fusobacterium being significantly enriched in the C-SP group. In the colon, the C-SP group showed significantly reduced crypt depth and zonula occludens-1 expression. The mRNA expression levels of pro-inflammatory cytokines, chemokines and tight junction proteins were significantly higher in the C-SP group. To further investigate whether salivary bacteria could persist in the intestine, the salivary microbiota was stained with carboxyfluorescein diacetate succinimidyl ester and transplanted into mice. We found that salivary microbes from both the PH group and the SP group could persist in the gut for at least 24 h. Thus, our data demonstrate that periodontitis may induce gut microbiota dysbiosis through the influx of salivary microbes.

Accelerated alveolar bone loss in a mouse model of inflammatory bowel disease and its relationship with intestinal inflammation.

BACKGROUND: Bone loss is a common complication of inflammatory bowel disease (IBD); however, few studies have focused on alveolar bone loss (ABL) in IBD. Herein, we systematically observed ABL in an interleukin (IL)-10 knockout (IL-10-/- ) mouse model of IBD and explored the possible mechanisms. METHODS: IL-10-/- and age-matched wild-type (WT) male mice were sacrificed every 2 weeks from 12 to 24 weeks of age. ABL was determined by microcomputed tomography. Periodontal and intestinal inflammation were evaluated using histological grading and inflammatory factor expression levels. Intestinal barrier integrity and cytokine levels in serum were examined by immunofluorescence and enzyme-linked immunosorbent assays, respectively. The expression of macrophage phenotype markers, including inducible nitric oxide synthase (iNOS), arginase-1 (Arg-1), and bone metabolic markers, including osteoprotegerin, receptor activator of nuclear factor-κB ligand (RANKL), were measured by immunohistochemistry. The macrophage phenotype in the periodontium was also examined by real-time quantitative polymerase chain reaction. RESULTS: Compared with WT mice, IL-10-/- mice exhibited significant ABL from 18 weeks of age. However, no significant differences were observed in the periodontium between the two groups in either histopathological scores or inflammatory factor levels. In the colon and ileum, these measurements significantly increased in IL-10-/- mice from 12 and 14 weeks, respectively. Correlation analysis also revealed that ABL in IL-10-/- mice was positively correlated with intestinal inflammation. Furthermore, IL-10-/- mice showed a destroyed intestinal barrier and higher serum levels of inflammatory factors. In both the intestine and periodontium, higher iNOS and lower Arg-1 levels, along with an increase in RANKL expression in the periodontium, were examined in IL-10-/- mice. CONCLUSIONS: An accelerated ABL spontaneously occurred in IL-10-/- mice and was correlated more with inflammation of the intestine than periodontium. Immunopathological changes may be the potential cause of abnormal alveolar bone metabolism.

Characteristics of a Bacteriophage, vB_Kox_ZX8, Isolated From Clinical Klebsiella oxytoca and Its Therapeutic Effect on Mice Bacteremia.

Klebsiella oxytoca is an important nosocomial and community-acquired opportunistic pathogenic Klebsiella and has become the second most prevalent strain in the clinic after K. pneumoniae. However, there have been few reports of bacteriophages used for treating K. oxytoca. In this study, a novel bacteriophage, vB_Kox_ZX8, which specifically infects K. oxytoca AD3, was isolated for the first time from human fecal samples. The biological characteristics of vB_Kox_ZX8 showed an incubation period of 10 min, a burst size of 74 PFU/cell, and a stable pH range of 3-11. Genomic bioinformatics studies of vB_Kox_ZX8 showed that it belongs to the genus Przondovirus, subfamily Studiervirinae, family Autographiviridae. The genome of vB_Kox_ZX8 is 39,398 bp in length and contains 46 putative open reading frames encoding functional proteins, such as DNA degradation, packaging, structural, lysin-holin, and hypothetical proteins. We further investigated the efficacy of vB_Kox_ZX8 phage in the treatment of mice with bacteremia caused by K. oxytoca infection. The results showed that vB_Kox_ZX8 (5 × 109 PFU/mouse) injected intraperitoneally alone was metabolized rapidly in BALB/c mice, and no significant side effects were observed in the control and treatment groups. Importantly, intraperitoneal injection with a single dose of phage vB_Kox_ZX8 (5 × 107 PFU/mouse) for 1 h post-infection saved 100% of BALB/c mice from bacteremia induced by intraperitoneal challenge with a minimum lethal dose of K. oxytoca AD3. However, all negative control mice injected with PBS alone died. Owing to its good safety, narrow host infectivity, high lysis efficiency in vitro, and good in vivo therapeutic effect, phage vB_Kox_ZX8 has the potential to be an excellent antibacterial agent for clinical K. oxytoca-caused infections.

Antibacterial mechanism and transcriptome analysis of ultra-small gold nanoclusters as an alternative of harmful antibiotics against Gram-negative bacteria.

In this work, a well-known Au25 NCs with high purity was prepared by simple one-pot reducing method. The as-synthesized Au25 NCs exhibited excellent antibacterial efficiency toward Gram-negative bacteria in a dose- and time-dependent manner, which could be used as nanoantibiotics to replace harmful antibiotics. The antibacterial assays showed that almost 100% bacteria were killed at lower concentration (100-150 µM) within a short time (30-60 min), providing a rapid and effective killing outcome for Gram-negative bacteria. After that, antibacterial mechanism was mainly investigated at cellular level via destruction of membrane integrity, disruption of antioxidant defense system, metabolic inactivation, DNA damage, as well as at molecular level via transcriptome analysis (RNA sequencing) for the first time. RNA sequencing results showed that differentially expressed genes (DEGs) related to biosynthesis of cell wall and membrane, glycolysis and TCA cycle, oxidative phosphorylation and DNA replication and repair were significantly affected. It was concluded that synergetic effect of membrane damage, oxidative stress, DNA damage and energy metabolism eventually led to the Gram-negative bacteria growth inhibition and death.

Au Nanoclusters Ameliorate Shigella Infectious Colitis by Inducing Oxidative Stress.

BACKGROUND: Shigella infection has always been a global burden, and it particularly threatens children between the ages of 1 and 5 years. Economically underdeveloped countries are dominated by Shigella flexneri infection. The most effective method to treat Shigella is antibiotics, but with the abuse of antibiotics and the prevalence of multidrug resistance, we urgently need a relatively safe non-antibiotic treatment to replace it. Ultrasmall Au nanoclusters (NCs) have special physical and chemical properties and can better interact with and be internalized by bacteria to disrupt the metabolic balance. The purpose of this study was to explore whether Au NCs may be a substitute for antibiotics to treat Shigella infections. METHODS: Au NCs and Shigella Sf301, R2448, and RII-1 were cocultured in vitro to evaluate the bactericidal ability of Au NCs. The degree of damage and mode of action of Au NCs in Shigella were clearly observed in images of scanning electron microscopy (SEM). In vivo experiments were conducted to observe the changes in body weight, clinical disease activity index (DAI) and colon (including length and histopathological sections) of mice treated with Au NCs. The effect of Au NCs was analysed by measuring the content of lipocalin-2 (LCN2) and Shigella in faeces. Next, the changes in Shigella biofilm activity, the release of reactive oxygen species (ROS), the changes in metabolism-related and membrane-related genes, and the effect of Au NCs on the body weight of mice were determined to further analyse the mechanism of action and effect. RESULTS: Au NCs (100 µM) interfered with oxidative metabolism genes, induced a substantial increase in ROS levels, interacted with the cell membrane to destroy it, significantly killed Shigella, and effectively alleviated the intestinal damage caused by Shigella in mice. The activity of the biofilm formed by Shigella was reduced. CONCLUSION: The effective antibacterial effect and good safety suggest that Au NCs represent a good potential alternative to antibiotics to treat Shigella infections.

Helicobacter pylori infection is correlated with the incidence of erosive oral lichen planus and the alteration of the oral microbiome composition.

BACKGROUND: Oral lichen planus (OLP), a common clinical oral disease, is associated with an increased risk of malignant transformation. The mechanism underlying the pathogenesis of OLP is unknown. Oral dysbacteriosis is reported to be one of the aetiological factors of OLP. Although Helicobacter pylori infection is associated with various oral diseases, the correlation between H. pylori infection and OLP is unclear. This study aimed to investigate the effect of H. pylori infection on OLP pathogenesis and oral microbiome composition in the Chinese population, which has a high incidence of H. pylori infection. RESULT: In this study, saliva samples of 30 patients with OLP (OLP group) and 21 negative controls (NC group) were collected. H. pylori infection was detected using the carbon-13-labeled urea breath test (UBT). The saliva samples were divided into the following four groups based on the H. pylori status: H. pylori-positive OLP (OLP+), H. pylori-positive NC (NC+), H. pylori-negative OLP (OLP-), and H. pylori-negative NC (NC-). Oral microbiome compositions were significantly different between the OLP and NC groups and between the OLP- and OLP+ groups. Compared with those in the OLP- group, those in the OLP+ group had a higher incidence of erosive OLP and higher levels of salivary cytokines. In contrast, the oral microbiome composition and cytokine levels were not significantly different between the NC- and NC+ groups. CONCLUSIONS: This is the first report to demonstrate that H. pylori infection is significantly correlated with the pathogenesis of erosive OLP.

The Association between Periodontitis and Inflammatory Bowel Disease: A Systematic Review and Meta-analysis.

BACKGROUND: It has been reported that patients with inflammatory bowel disease (IBD) are more susceptible to periodontitis. However, data regarding the risk of periodontitis in IBD patients are scarce, and results from individual studies remain controversial. The aim of this study is to investigate the risk of periodontitis in IBD patients. METHODS: Web of Science, PubMed, and Embase were searched for studies investigating the risk of periodontitis in the IBD patient population from Jan. 2000 to Nov. 2020. Articles were included if they contained the number of people with IBD diagnosed with periodontitis (or periodontal disease parameters) compared with a control group. Case reports, reviews, animal studies, and articles without available abstracts were excluded. A pooled odds ratio (OR) and 95% confidence interval (CI) were calculated to assess the association between periodontitis and IBD. RESULTS: Six studies were included in the meta-analysis. The overall risk of periodontitis was significantly higher in IBD patients than controls (OR: 2.10, 95% CI: 1.60-2.74; I 2 = 27%). In particular, Crohn's disease (CD) and ulcerative colitis (UC) were both linked to an increased risk of periodontitis (OR: 1.72, 95% CI: 1.36-2.19; I 2 = 0% for CD vs. OR:2.39, 95% CI: 1.19-4.80; I 2 = 85% for UC). CONCLUSIONS: IBD patients are at higher risk of periodontitis than controls. After subgroup analysis, the elevated risk remained significant when analyzing CD or UC alone. UC patients were at higher risk of developing periodontitis than CD patients.

l-cysteine-modified chiral gold nanoparticles promote periodontal tissue regeneration.

Gold nanoparticles (AuNPs) with surface-anchored molecules present tremendous potential in tissue regeneration. However, little is known about chiral-modified AuNPs. In this study, we successfully prepared L/D-cysteine-anchored AuNPs (L/D-Cys-AuNPs) and studied the effects of chiral-modified AuNPs on osteogenic differentiation and autophagy of human periodontal ligament cells (hPDLCs) and periodontal tissue regeneration. In vitro, more L-Cys-AuNPs than D-Cys-AuNPs tend to internalize in hPDLCs. L-Cys-AuNPs also significantly increased the expression of alkaline phosphatase, collagen type 1, osteocalcin, runt-related transcription factor 2, and microtubule-associated protein light chain 3 II and decreased the expression of sequestosome 1 in hPDLCs compared to the expression levels in the hPDLCs treated by D-Cys-AuNPs. In vivo tests in a rat periodontal-defect model showed that L-Cys-AuNPs had the greatest effect on periodontal-tissue regeneration. The activation of autophagy in L-Cys-AuNP-treated hPDLCs may be responsible for the cell differentiation and tissue regeneration. Therefore, compared to D-Cys-AuNPs, L-Cys-AuNPs show a better performance in cellular internalization, regulation of autophagy, cell osteogenic differentiation, and periodontal tissue regeneration. This demonstrates the immense potential of L-Cys-AuNPs for periodontal regeneration and provides a new insight into chirally modified bioactive nanomaterials.

Gold Nanoparticles Combined Human ß-Defensin 3 Gene-Modified Human Periodontal Ligament Cells Alleviate Periodontal Destruction via the p38 MAPK Pathway.

Periodontitis is a chronic inflammatory disease with plaques as the initiating factor, which will induce the destruction of periodontal tissues. Numerous studies focused on how to obtain periodontal tissue regeneration in inflammatory environments. Previous studies have reported adenovirus-mediated human ß-defensin 3 (hBD3) gene transfer could potentially enhance the osteogenic differentiation of human periodontal ligament cells (hPDLCs) and bone repair in periodontitis. Gold nanoparticles (AuNPs), the ideal inorganic nanomaterials in biomedicine applications, were proved to have synergetic effects with gene transfection. To further observe the potential promoting effects, AuNPs were added to the transfected cells. The results showed the positive effects of osteogenic differentiation while applying AuNPs into hPDLCs transfected by adenovirus encoding hBD3 gene. In vivo, after rat periodontal ligament cell (rPDLC) transplantation into SD rats with periodontitis, AuNPs combined hBD3 gene modification could also promote periodontal regeneration. The p38 mitogen-activated protein kinase (MAPK) pathway was demonstrated to potentially regulate both the in vitro and in vivo processes. In conclusion, AuNPs can promote the osteogenic differentiation of hBD3 gene-modified hPDLCs and periodontal regeneration via the p38 MAPK pathway.

Gold Nanoparticles Promote the Bone Regeneration of Periodontal Ligament Stem Cell Sheets Through Activation of Autophagy.

OBJECTIVE: Cell sheet technology (CST) is advantageous for repairing alveolar bone defects in clinical situations, and osteogenic induction before implantation may result in enhanced bone regeneration. Herein, we observed the effect of gold nanoparticles (AuNPs) on osteogenic differentiation of periodontal ligament stem cell (PDLSC) sheets and explored their potential mechanism of action. METHODS: PDLSCs were cultured in cell sheet induction medium to obtain cell sheets. PDLSC sheets were treated with or without AuNPs. Alkaline phosphatase, alizarin red S, von Kossa, and immunofluorescence staining were used to observe the effects of AuNPs on the osteogenic differentiation of PDLSC sheets. Western blotting was performed to evaluate the osteogenic effects and autophagy activity. The cell sheets were transplanted into the dorsa of nude mice, and bone regeneration was analyzed by micro-CT and histological staining. RESULTS: AuNPs could promote the osteogenic differentiation of PDLSC sheets by upregulating bone-related protein expression and mineralization. The 45-nm AuNPs were more effective than 13-nm AuNPs. Additional analysis demonstrated that their ability to promote differentiation could depend on activation of the autophagy pathway through upregulation of microtubule-associated protein light chain 3 and downregulation of sequestosome 1/p62. Furthermore, AuNPs significantly promoted the bone regeneration of PDLSC sheets in ectopic models. CONCLUSION: AuNPs enhance the osteogenesis of PDLSC sheets by activating autophagy, and 45-nm AuNPs were more effective than 13-nm AuNPs. This study may provide an AuNP-based pretreatment strategy for improving the application of CST in bone repair and regeneration.