Exploring the bi-directional relationship between periodontitis and dyslipidemia: a comprehensive systematic review and meta-analysis.

AIM: As periodontitis and dyslipidemia are diseases that occur with high incidence, the relationship between them has attracted much attention. Previous studies on these diseases have tended to focus on lipid parameters and periodontitis, we aimed to investigate the relationship between dyslipidemia and periodontitis. MATERIALS AND METHODS: A comprehensive search to identify the studies investigating the relationship between dyslipidemia and periodontitis was performed on PubMed, Web of Science and Cochrane Library before the date of August, 2023. Studies were considered eligible if they contained data on abnormal blood lipid parameters and periodontitis. Studies that reported mean differences and 95% confidence intervals or odds ratios were used. RESULTS: A total of 73 publications were included in the meta-analysis. Hyper total cholesterol (TC), triglycerides (TGs), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL) and lower high-density lipoprotein (HDL) levels are risk factors for periodontitis. Periodontal disease is a risk factor for high TG and low HDL levels. Three months after periodontal treatment, the levels of TC, TG and HDL were significantly improved, and statin treatment only improved gingival index (GI) levels compared to that of the dietary control. CONCLUSIONS: The findings reported here suggest that the mutual promotion of periodontitis and dyslipidemia can be confirmed. Non-surgical periodontal therapy may improve lipid abnormalities. It can't be demonstrated whether systematic application of statins have a better effect on the improvement in periodontal status in patients with dyslipidemia compared to that of the control.

The niche-specialist and age-related oral microbial ecosystem: crosstalk with host immune cells in homeostasis.

Although characterization of the baseline oral microbiota has been discussed, the current literature seems insufficient to draw a definitive conclusion on the interactions between the microbes themselves or with the host. This study focuses on the spatial and temporal characteristics of the oral microbial ecosystem in a mouse model and its crosstalk with host immune cells in homeostasis. The V3V4 regions of the 16S rRNA gene of 20 samples from four niches (tongue, buccal mucosa, keratinized gingiva and hard palate) and 10 samples from two life stages (adult and old) were analysed. Flow cytometry (FCM) was used to investigate the resident immune cells. The niche-specialist and age-related communities, characterized based on the microbiota structure, interspecies communications, microbial functions and interactions with immune cells, were addressed. The phylum Firmicutes was the major component in the oral community. The microbial community profiles at the genus level showed that the relative abundances of the genera Bacteroides, Lactobacillus and Porphyromonas were enriched in the gingiva. The abundance of the genera Streptococcus, Faecalibaculum and Veillonella was increased in palatal samples, while the abundance of Neisseria and Bradyrhizobium was enriched in buccal samples. The genera Corynebacterium, Stenotrophomonas, Streptococcus and Fusobacterium were proportionally enriched in old samples, while Prevotella and Lacobacillus were enriched in adult samples. Network analysis showed that the genus Lactobacillus performed as a central node in the buccal module, while in the gingiva module, the central nodes were Nesterenkonia and Hydrogenophilus. FCM showed that the proportion of Th1 cells in the tongue samples (38.18 % [27.03-49.34 %]) (mean [range]) was the highest. The proportion of γδT cells in the buccal mucosa (25.82 % [22.1-29.54 %]) and gingiva (20.42 % [18.31-22.53 %]) samples was higher (P<0.01) than those in the palate (14.18 % [11.69-16.67 %]) and tongue (9.38 % [5.38-13.37 %] samples. The proportion of Th2 (31.3 % [16.16-46.44 %]), Th17 (27.06 % [15.76-38.36 %]) and Treg (29.74 % [15.71-43.77 %]) cells in the old samples was higher than that in the adult samples (P<0.01). Further analysis of the interplays between the microbiomes and immune cells indicated that Th1 cells in the adult group, nd Th2, Th17 and Treg cells in the old group were the main immune factors strongly associated with the oral microbiota. For example, Th2, Th17 and Treg cells showed a significantly positive correlation with age-related microorganisms such as Sphingomonas, Streptococcus and Acinetobacter, while Th1 cells showed a negative correlation. Another positive correlation occurred between Th1 cells and several commensal microbiomes such as Lactobacillus, Jeotgalicoccus and Sporosarcina. Th2, Th17 and Treg cells showed the opposite trend. Together, our findings identify the niche-specialist and age-related characteristics of the oral microbial ecosystem and the potential associations between the microbiomes and the mucosal immune cells, providing critical insights into mucosal microbiology.

[Research Updates: The Role of Interaction between Oral Microbiota, Immune Cells, and Epithelial Barrier in Oral Mucosal Homeostasis and Pathogenesis].

In a healthy state, the interaction between the oral microorganisms, mucosal immune cells and epithelial barrier can maintain the oral microecological stability. However, the oral microecology is disrupted under a diseased state and various pathogenic bacteria and their virulence factors and metabolites irritate the immune system, which causes direct or indirect damage to the epithelial barrier, promotes the pathogenesis and progression of oral mucosal diseases, and triggers immune inflammatory response or the irreversible transformation from inflammation into cancer. We herein reviewed the interaction between oral microorganisms, immune cells and epithelial barrier from two perspectives, the maintenance of the oral homeostasis and the pathogenesis of oral mucosal diseases. We intended to gain further understanding of the oral mucosal homeostasis and the mechanism of action of the pathogenesis and progression of oral mucosal diseases, and to provide thereby ideas and scientific and theoretical basis for developing new strategies for the diagnosis and treatment of oral mucosal diseases through re-establishing mucosal homeostasis.

Crosstalk between the oral microbiota, mucosal immunity, and the epithelial barrier regulates oral mucosal disease pathogenesis.

Oral mucosal disease (OMD), which is also called soft tissue oral disease, is described as a series of disorders or conditions affecting the mucosa and soft tissue in the oral cavity. Its etiology is unclear, but emerging evidence has implicated the influence of the composition of the oral mucosa and saliva-resident microbiota. In turn, this dysbiosis effects the immune response balance and epithelial barrier function, followed by the occurrence and progression of OMD. In addition, oral microbial dysbiosis is diverse in different types of diseases and different disease progressions, suggesting that key causal pathogens may exist in various oral pathologies. This narrative literature review primarily discusses the most recent findings focusing on how microbial dysbiosis communicates with mucosal adaptive immune cells and the epithelial barrier in the context of five representative OMDs, including oral candidiasis (OC), oral lichen planus (OLP), recurrent aphthous ulcer (RAU), oral leukoplakia (OLK), and oral squamous cell carcinoma (OSCC), to provide new insight into the pathogenetic mechanisms of OMDs.

High Abundance of Intratumoral γδ T Cells Favors a Better Prognosis in Head and Neck Squamous Cell Carcinoma: A Bioinformatic Analysis.

γδ T cells are a small subset of unconventional T cells that are enriched in the mucosal areas, and are responsible for pathogen clearance and maintaining integrity. However, the role of γδ T cells in head and neck squamous cell carcinoma (HNSCC) is largely unknown. Here, by using RNA-seq data from The Cancer Genome Atlas (TCGA), we discovered that HNSCC patients with higher levels of γδ T cells were positively associated with lower clinical stages and better overall survival, and high abundance of γδ T cells was positively correlated with CD8+/CD4+ T cell infiltration. Gene ontology and pathway analyses showed that genes associated with T cell activation, proliferation, effector functions, cytotoxicity, and chemokine production were enriched in the group with a higher γδ T cell abundance. Furthermore, we found that the abundance of γδ T cells was positively associated with the expression of the butyrophilin (BTN) family proteins BTN3A1/BTN3A2/BTN3A3 and BTN2A1, but only MICB, one of the ligands of NKG2D, was involved in the activation of γδ T cells, indicating that the BTN family proteins might be involved in the activation and proliferation of γδ T cells in the tumor microenvironment of HNSCC. Our results indicated that γδ T cells, along with their ligands, are promising targets in HNSCC with great prognostic values and treatment potentials.

CaSR as a Therapeutic Target and Tool in Human Dental Pulp: A Concise Review and Novel Hypothesis.

PURPOSE: To review the essential characteristics of calcium sensing receptor (CaSR) and explore the hypothesis that elevated extracellular calcium ions (Ca2+) may affect the odontogenic/osteogenic differentiation and mineralisation of human dental pulp cells (hDPCs) through the CaSR signal. MATERIALS AND METHODS: Based on a literature search of databases using different combinations of the key words and our previous researches, we gleaned the following important viewpoints. RESULTS: The Ca2+ released from pulp capping materials plays an essential role in maintaining the viability and function of human dental pulp, and elevated extracellular Ca2+ concentrations can promote the odontogenic/osteogenic differentiation and mineralisation of hDPCs. Ca2+ is the primary physiological ligand of the CaSR, which has been reported to be widely expressed in a broad range of cells, including various osteoblast-like cell lines, osteoprogenitor cells, and mature osteoblasts. hDPCs consist of different subpopulations and have been shown to share phenotypical features with osteoblasts. Thus, we speculated that hDPCs also express CaSR and respond to extracellular Ca2+ via this receptor. Calcimimetics are indirect allosteric regulators of CaSR function and can increase the receptor's sensitivity to ambient Ca2+. CONCLUSION: The local use of calcimimetics and calcium-based pulp capping materials could create an option for promoting the Ca2+ influx of hDPCs from the extracellular space via the CaSR. Such elevated Ca2+ concentrations could enhance the odontogenic/osteogenic differentiation and mineralisation of hDPCs and eventually improve the success rate of direct pulp capping treatments in patients suffering from accidental dental pulp exposure.

Identification of a Calcium-sensing Receptor in Human Dental Pulp Cells That Regulates Mineral Trioxide Aggregate-induced Mineralization.

INTRODUCTION: The purpose of this study was to verify the expression of the calcium-sensing receptor (CaSR) and its role in mineral trioxide aggregate (MTA)-induced odontoblastic differentiation and mineralization in human dental pulp cells (hDPCs). METHODS: The expression of CaSR in human dental pulp tissue and hDPCs was detected using immunohistochemical and immunofluorescent assays. Then, hDPCs were cultured in specific medium supplemented with defined concentrations of MTA dilute alone or in combination with calcimimetic R-568 (a positive allosteric modulator of CaSR [Tocris Bioscience, Bristol, UK]), and cell viability was monitored by Cell Counting Kit-8 (Dojindo Molecular Technologies, Kumamoto, Japan) analysis. Alkaline phosphatase activity, alizarin red S staining, quantitative real-time polymerase chain reaction, and Western blot were used to investigate the gene/protein expression of odontoblastic-associated markers and CaSR in medium supplemented with different combinations of diluted MTA, R-568, and calcilytic Calhex 231 (a negative allosteric modulator of CaSR [Sigma-Aldrich, St Louis, MO]). RESULTS: CaSR was slightly expressed in the central pulp tissue, whereas it was strongly expressed in the odontoblast layer, plasma membrane, and cytoplasm of hDPCs. Cell Counting Kit-8 assay indicated maximum cell viability in cultures treated with 1:8 diluted MTA additives. Compared with undifferentiated controls, the cells at the early stage of odontoblastic differentiation exhibited lower CaSR protein expression. The combination of 1:8 diluted MTA with 0.1 and 1.0 µmol/L R-568 led to significantly increased cell vitality but decreased alkaline phosphatase activity and mineralized deposit formation, and this negative effect could be attenuated by 1.0 µmol/L Calhex 231 supplementation. Quantitative polymerase chain reaction results showed a significant up-regulation of RUNX2, DSPP, DMP-1, and OCN gene expression in the 1 µmol/L R-568-treated hDPCs. Western blot analysis indicated that the treatment by MTA and R-568 alone or their combination gave no clear trend on the protein levels of CaSR and dentin sialophosphoprotein, whereas Calhex 231 can increase their expressions. In addition, the up-regulation of Akt phosphorylation was observed in R-568- and Calhex 231-treated hDPCs. CONCLUSIONS: Our data indicated that CaSR is expressed in human dental pulp and hDPCs and that it can negatively or positively regulate MTA-induced mineralization of hDPCs via the phosphoinositide 3-kinase/Akt pathway in a ligand-dependent manner, suggesting a therapeutic target for modulating reparative dentin formation.

Enterococcus faecalis lipoteichoic acid regulates macrophages autophagy via PI3K/Akt/mTOR pathway.

Enterococcus faecalis (E. faecalis) infection is considered an important etiological factor for the development of persistent apical periodontitis (PAP), but the exact mechanisms of autophagy between E. faecalis and immune cells remain unknown. In this study, we elucidated how E. faecalis lipoteichoic acid (LTA) is associated with macrophages autophagy. We found that E. faecalis LTA apparently activated macrophage autophagy with significant increase of autophagosomes and autophagy relative protein. Meanwhile, we noticed significantly decreasing expression of p-Akt and p-mTOR. However, these effect were absent in macrophages knockdown of Beclin1. In summary, these findings suggested E. faecalis LTA may increased macrophages autophagy via inhibiting PI3K/Akt/mTOR pathway and this process was Beclin1 dependent.

Overexpression of Tim-3 reduces Helicobacter pylori-associated inflammation through TLR4/NFκB signaling in vitro.

The present study aimed to investigate the interaction between T-cell immunoglobulin and mucin-domain-containing molecule-3 (Tim-3) and Toll-like receptor 4 (TLR4)/nuclear factor κB (NF­κB) signaling in Helicobacter pylori-infected RAW264.7 macrophage cells. RAW264.7 cells were co­cultured with H. pylori SS1 at different bacteria/cell ratios, and subsequently the mRNA expression of Tim­3, TLR4, and myeloid differentiation factor 88 (MyD88) was measured by reverse transcription-quantitative polymerase chain reaction (RT­qPCR). Furthermore, the effect of Tim­3 overexpression was examined by transfection of RAW264.7 with pLVX-IRES-ZsGreen-Tim-3 and co­culturing with H. pylori. mRNA and protein expression levels were then analyzed for Tim­3, TLR4, MyD88, and phosphorylated (p­) NF­κB by RT­qPCR and western blot analysis respectively. The concentrations of pro­inflammatory cytokines [tumor necrosis factor­α (TNF­α), interleukin 6 (IL-6), interferon­Î³ (IFN­Î³) and interleukin 10 (IL­10)] released in the culture supernatants were measured by ELISA. H. pylori stimulation resulted in a significant increase of Tim­3, TLR4, and MyD88 mRNA expression in RAW264.7 cells. H. pylori stimulation upregulated Tim­3 expression even in the Tim­3­overexpressing RAW264.7 cells compared with unstimulated cells. TLR4, MyD88, and pNF­κB protein expression and pro­inflammatory cytokines (TNF­α, IL­6, and IFN­Î³) release levels were increased in the control RAW264.7 cells following H. pylori infection, but not in the Tim-3-overexpressing RAW264.7 cells. By contrast, IL­10 levels were decreased following H. pylori infection in both control and Tim­3­overexpressing RAW264.7 cells. Overexpression of Tim-3 reduced H. pylori-associated inflammation in RAW264.7 macrophages, by downregulating expression of proteins in the TLR4 pathway and release of pro­inflammatory cytokines. These findings suggest that Tim­3 serves a crucial role in the negative regulation of H. pylori-associated inflammation and may be a novel therapeutic target for H. pylori infection.

The Starvation Resistance and Biofilm Formation of Enterococcus faecalis in Coexistence with Candida albicans, Streptococcus gordonii, Actinomyces viscosus, or Lactobacillus acidophilus.

INTRODUCTION: Enterococcus faecalis is the most frequently detected species in root canal-treated teeth, and it is able to survive under starvation conditions. However, persistent periapical disease is often caused by multispecies. The aim of this study was to explore the survival of E. faecalis in starvation conditions and biofilm formation with the 4 common pathogenic species. METHODS: A dual-species model of Candida albicans, Streptococcus gordonii, Actinomyces viscosus, or Lactobacillus acidophilus in combination with E. faecalis was established and allowed to grow in phosphate-buffered saline for the examination of starvation survival. Cefuroxime sodium and vancomycin at a concentration of 100 mg/L were added into brain-heart infusion plate agar to count the 2 bacteria separately in the dual species. Scanning electron microscopy was used to observe the dual species and multiple species on the root canal dentin of bovine teeth for 48 hours. A confocal laser scanning microscope was used to show the 4 groups of dual-species biofilms on substrates with glass bottoms for 48 hours. RESULTS: E. faecalis was more resistant to starvation in coexistence with C. albicans, S. gordonii, A. viscosus, or L. acidophilus, and S. gordonii was completely inhibited in coexistence with E. faecalis. The dual-species biofilm showed that E. faecalis formed thicker and denser biofilms on the root canal dentin and glass slides in coexistence with S. gordonii and A. viscosus than C. albicans and L. acidophilus. CONCLUSIONS: The multispecies community is conducive to the resistance to starvation of E. faecalis and biofilm formation in root canals.

Overexpression of HMGB1 A-box reduced lipopolysaccharide-induced intestinal inflammation via HMGB1/TLR4 signaling in vitro.

AIM: To investigate the inhibitory effects and mechanism of high mobility group box (HMGB)1 A-box in lipopolysaccharide (LPS)-induced intestinal inflammation. METHODS: Overexpression of HMGB1 A-box in human intestinal epithelial cell lines (SW480 cells) was achieved using the plasmid pEGFP-N1. HMGB1 A-box-overexpressing SW480 cells were stimulated with LPS and co-culturing with human monocyte-like cell lines (THP-1 cells) using a Transwell system, compared with another HMGB1 inhibitor ethyl pyruvate (EP). The mRNA and protein levels of HMGB1/toll-like receptor (TLR) 4 signaling pathways [including HMGB1, TLR4, myeloid differentiation factor88 (MYD88), Phosphorylated Nuclear Factor κB (pNF-κB) p65] in the stimulated cells were determined by real-time polymerase chain reaction and Western blotting. The levels of the proinflammatory mediators [including HMGB1, interleukin (IL)-1ß, IL-6 and tumor necrosis factor (TNF)-α] in the supernatants of the stimulated cells were determined by ELISA. RESULTS: EP downregulated the mRNA and protein levels of HMGB1, inhibited the TLR4 signaling pathways (TLR4, MYD88 and pNF-κB p65) and reduced the secretion of proinflammatory mediators (HMGB1, IL-1ß, IL-6 and TNF-α) in the SW480 and THP-1 cells activated by LPS but not in the unstimulated cells. Activated by LPS, the overexpression of HMGB1 A-box in the SW480 cells also inhibited the HMGB1/TLR4 signaling pathways and reduced the secretion of these proinflammatory mediators in the THP-1 cells but not in the transfected and unstimulated cells. CONCLUSION: HMGB1 A-box, not only EP, can reduce LPS-induced intestinal inflammation through inhibition of the HMGB1/TLR4 signaling pathways.