Neutrophil extracellular traps and extracellular histones potentiate IL-17 inflammation in periodontitis

The Relationship Between Alkaline Phosphatase and Periodontitis: The Mediating Role of Cranial Bone Mineral Density

BACKGROUND

Periodontitis is a common chronic disease characterized by the destruction of periodontal tissues and the resorption of alveolar bone, which severely impacts the quality of life of patients. Alkaline phosphatase (ALP), as a crucial marker of bone metabolism, is involved in the bone formation process. However, the mechanisms linking ALP to periodontitis remain unclear. Bone mineral density (BMD) of the skull is an important indicator reflecting bone mineral content and bone strength, yet its mediating role in the relationship between ALP and periodontitis has not been thoroughly investigated.

OBJECTIVE

This study aimed to explore the association between serum ALP and the risk of periodontitis and to evaluate the potential mediating role of cranial BMD in this relationship, with the goal of providing new insights into the etiology of periodontitis and informing treatment strategies.

METHODS

Data from periodontitis patients from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014 were utilized with ALP as the independent variable, periodontitis as the dependent variable, and cranial BMD as the mediating variable. A logistic regression model was used to analyse the relationship between ALP and periodontitis, and subgroup analyses were conducted to explore the association between ALP and periodontitis in different subgroups. Restricted cubic splines (RCS) were used to explore the nonlinear relationship between the two. Additionally, mediation analysis was employed to study the potential mediating role of cranial BMD on the association between ALP and periodontitis.

RESULTS

After adjusting for confounding variables, ALP showed a significant positive association with periodontitis (OR: 1.006, 95% CI: 1.002-1.011, P < .05). Subgroup analyses showed that this association was particularly pronounced in males, drinkers, and individuals lacking physical activities. RCS analysis revealed a nonlinear relationship between ALP and periodontitis (P-non-linear = 0.0006), with a threshold level of 68 U/L. The mediation analysis revealed that cranial BMD played a mediating role of 2.71% in the relationship between ALP and periodontitis (P = .006). Furthermore, ALP was significantly negatively correlated with cranial BMD (β = -0.0016, 95% CI: -0.0024 to -0.0007, P < .001).

CONCLUSION

Elevated serum ALP levels were positively associated with an increased risk of periodontitis, and cranial BMD partially mediated this association. Monitoring ALP levels may contribute to the early diagnosis and intervention of periodontitis, while targeting bone metabolism regulation could offer a novel direction for the treatment of periodontitis.

Single-cell atlas of human gingiva unveils a NETs-related neutrophil subpopulation regulating periodontal immunity

INTRODUCTION

Exaggerated neutrophil recruitment and activation are the major features of pathological alterations in periodontitis, in which neutrophil extracellular traps (NETs) are considered to be responsible for inflammatory periodontal lesions. Despite the critical role of NETs in the development and progression of periodontitis, their specific functions and mechanisms remain unclear.

OBJECTIVES

To demonstrate the important functions and specific mechanisms of NETs involved in periodontal immunopathology.

METHODS

We performed single-cell RNA sequencing on gingival tissues from both healthy individuals and patients diagnosed with periodontitis. High-dimensional weighted gene co-expression network analysis and pseudotime analysis were then applied to characterize the heterogeneity of neutrophils. Animal models of periodontitis were treated with NETs inhibitors to investigate the effects of NETs in severe periodontitis. Additionally, we established a periodontitis prediction model based on NETs-related genes using six types of machine learning methods. Cell-cell communication analysis was used to identify ligand-receptor pairs among the major cell groups within the immune microenvironment.

RESULTS

We constructed a single-cell atlas of the periodontal microenvironment and obtained nine major cell populations. We further identified a NETs-related subgroup (NrNeu) in neutrophils. An in vivo inhibition experiment confirmed the involvement of NETs in gingival inflammatory infiltration and alveolar bone absorption in severe periodontitis. We further screened three key NETs-related genes (PTGS2, MME and SLC2A3) and verified that they have the potential to predict periodontitis. Moreover, our findings revealed that gingival fibroblasts had the most interactions with NrNeu and that they might facilitate the production of NETs through the MIF-CD74/CXCR4 axis in periodontitis.

CONCLUSION

This study highlights the pathogenic role of NETs in periodontal immunity and elucidates the specific regulatory relationship by which gingival fibroblasts activate NETs, which provides new insights into the clinical diagnosis and treatment of periodontitis.

Mechanisms and immune crosstalk of neutrophil extracellular traps in response to infection

Neutrophil extrusion of neutrophil extracellular traps (NETs) in a process called NETosis provides immune defense against extracellular bacteria. It has been observed that bacteria are capable of activating neutrophils to release NETs that subsequently kill them or at least prevent their local spread within host tissue. However, existing studies have mainly focused on the isolated function of NETs, with less attention given to their anti-bacterial mechanisms through interactions with other immune cell populations. The net effect of these complex intercellular interactions, which may act additively, synergistically, or antagonistically, is a critical determinant in the outcomes of host-pathogen interactions. This review summarizes the mechanisms underlying classic NET formation and their crosstalk with the immune system, offering novel insights aimed at balancing the anti-microbial function with their potential inflammatory risks.

Pt-Induced Sublattice Distortion Facilitates Enzyme Cascade Reactions for Eradicating Intracellularly Methicillin-Resistant Staphylococcus aureus and Enhancing Diabetic Wound Healing

Metal oxide nanozymes hold significant potential in combating bacterial infections; however, their ordered crystal structures limit the enhancement of catalytic activity, posing challenges in addressing clinical needs for eliminating intracellularly colonized bacteria. Here, we report the development of an integrated diagnostic-therapeutic microneedle patch incorporates the Res@PtZ-Z nanozyme hybrid. Res@PtZ-Z consists of a ZIF shell loaded with the natural compound resveratrol (Res), encapsulating a Pt-doped zinc oxide (ZnO) nanozyme core (PtZ). The Res component modulates charge distribution on the ZIF shell and attenuates bacterial virulence, thereby promoting the uptake of Res@PtZ-Z by host cells. The PtZ core, doped with Pt4+ to induce sublattice distortion in ZnO, exhibits oxidase-like, peroxidase-like, and catalase-like activities. Under intracellular hypoxic conditions, the cascade of these enzyme-like activities ensures a sustained generation of reactive oxygen species (ROS), enabling robust antibacterial effects. Additionally, Res@PtZ-Z enables real-time infection monitoring by oxidizing the 3,3',5,5'-tetramethylbenzidine (TMB) substrate to produce a distinct colorimetric response. This approach addresses both methicillin-resistant Staphylococcus aureus (MRSA) invasion and intracellular persistence, contributing to improved infection management and promoting wound healing.

Interleukin-35 inhibits NETs to ameliorate Th17/Treg immune imbalance during the exacerbation of cigarette smoke exposed-asthma via gp130/STAT3/ferroptosis axis

Cigarette smoke (CS) exposure amplifies neutrophil accumulation. IL-35, a novel cytokine with anti-inflammatory properties, is involved in protection against asthma. However, the biological roles of neutrophils and the precise molecular mechanisms of IL-35 in CS exposed-asthma remain unclear. We showed that the exacerbation of CS exposed-asthma leads to dramatically increased neutrophil counts and an imbalance in DC-Th17/Treg immune responses. RNA sequencing revealed that NETs, part of a key biological process in neutrophils, were significantly upregulated in the context of CS exposed-asthma exacerbation and that IL-35 treatment downregulated NET-associated gene expression. Targeted degradation of NETs, rather than neutrophil depletion, alleviated the CS exposed-asthma. Mechanistically, STAT3 phosphorylation promoted ferroptosis, exacerbating NET release, which in turn enhanced dendritic cell (DC) antigen presentation, activated T cells, and specifically promoted Th17 cell differentiation while inhibiting Treg cells. IL-35 acting on the gp130 receptor alleviated STAT3-mediated ferroptosis-associated NET formation. In summary, our study revealed a novel mechanism by which IL-35 inhibited NET formation, subsequently alleviating neutrophilic inflammation and restoring the DC-Th17/Treg imbalance in CS exposed-asthma, highlighting the potential of IL-35 as a targeted therapeutic strategy.

Sodium propionate protects against bronchopulmonary dysplasia by inhibiting IL-17-mediated apoptosis of alveolar epithelial cells

Sodium propionate (SP) has been shown to enhance alveolar growth retardation in Bronchopulmonary Dysplasia (BPD), but the mechanism remains unclear. The aim of this study is to explore the potential mechanism of SP in the treatment of BPD by utilizing animal and cell models along with bioinformation analysis. Neonatal mice were exposed to either air (21% O2) or hyperoxia (85% O2) from the first day after birth to establish the BPD model. The neonatal mice were intraperitoneally injected with normal saline (control group) or SP (500 mg/kg, SP group) from day 8 to day 14. SP significantly reduced the inflammatory condition of alveolar septal thickening, and decreased the alveolar fusion and mitigated weight loss in BPD mice. ELISA results demonstrated that SP significantly inhibited the secretion of IL-17, IL-6 and TNFα. Transcriptome analysis confirmed that IL-17 signaling pathway is closely related to the therapeutic effects of SP on BPD. In addition, MX2, MMP10, IL-11, ZMAT4 and SEC1 genes were identified as key and potential targets involved in the mechanism of SP treating BPD. Meanwhile, in mouse alveolar epithelial cells, apoptosis was induced by hyperoxia, but it was reduced following SP intervention. The expression of IL-17 pathway related genes: IL-17A, IL-6, TNFα and cox2 was decreased in hyperoxia treated cells after SP intervention. In conclusion, through transcriptome analysis, animal and cell experiments, we explored the role of sodium propionate in attenuating apoptosis in a BPD model through IL-17 pathway.

The dual role of IL-17 in periodontitis regulating immunity and bone homeostasis

Periodontitis is a common dysbiotic bacteria-induced inflammatory disease characterized by alveolar bone resorption, leading to tooth loss. Interleukin-17 (IL-17) is a critical cytokine with dual roles in periodontium, which exerts the function of host defense, including neutrophil recruitment, phagocytosis, and mucosal immunity. However, excessive expression of IL-17 causes persistent chronic inflammation, local tissue breakdown, and bone loss. This review highlights the protective and pathological functions of IL-17 on immunity and bone homeostasis in inflammatory bone-related diseases. We also provide the latest findings with IL-17 knockout mice in periodontitis and highlight complex immune responses under various experimental models. This may provide a critical perception of inflammatory bone-related disease management using an immune-modulating strategy.

Inflammation-triggered Gli1+ stem cells engage with extracellular vesicles to prime aberrant neutrophils to exacerbate periodontal immunopathology

Periodontitis is a prevalent and progressive detrimental disease characterized by chronic inflammation, and the immunopathological mechanisms are not yet fully understood. Mesenchymal stem cells (MSCs) play crucial roles as immunoregulators and maintain tissue homeostasis and regeneration, but their in vivo function in immunopathology and periodontal tissue deterioration is still unclear. Here, we utilized multiple transgenic mouse models to specifically mark, ablate and modulate Gli1+ cells, a critical and representative subset of MSCs in the periodontium, to explore their specific role in periodontal immunopathology. We revealed that Gli1+ cells, upon challenge with an inflammatory microenvironment, significantly induce rapid trafficking and aberrant activation of neutrophils, thus exacerbating alveolar bone destruction. Mechanistically, extracellular vesicles (EVs) released by Gli1+ cells act as crucial immune regulators in periodontal tissue, mediating the recruitment and activation of neutrophils through increased neutrophil generation of reactive oxygen species and stimulation of nuclear factor kappa-B signaling. Furthermore, we discovered that CXC motif chemokine ligand 1 (CXCL1) is exposed on the surface of EVs derived from inflammation-challenged Gli1+ cells to prime aberrant neutrophils via the CXCL1-CXC motif chemokine receptor 2 (CXCR2) axis. Importantly, specific inhibition of EV release from Gli1+ cells or pharmacological therapy with GANT61 ameliorates periodontal inflammation and alveolar bone loss. Collectively, our findings identify previously unrecognized roles of Gli1+ cells in orchestrating infiltration and promoting aberrant activation of neutrophils under inflammation, which provides pathological insights and potential therapeutic targets for periodontitis.

Eosinophil extracellular traps drive T follicular helper cell differentiation via VIRMA-dependent MAF stabilization in bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by the presence of pathogenic autoantibodies and a substantial influx of immune cells into skin lesions. However, the role of eosinophils in BP remains inadequately elucidated.

OBJECTIVE

We sought to determine the pathologic involvement of eosinophils and eosinophil extracellular traps (EETs) in BP.

METHODS

Human samples collected from BP patients and healthy controls were utilized to explore the potential role of eosinophils and their EETs in BP patients through serologic detection, flow cytometry, and immunofluorescence. Naive CD4+ T cells isolated from healthy donors were stimulated and subjected to further analysis via RNA sequencing. We additionally evaluated the potential of targeting EETs in BP180-immunized BP-like mice and in in vitro settings.

RESULTS

We found that elevated levels of eosinophils and EETs in BP patients correlated with disease severity. The DNA components within EETs played a crucial role in driving the differentiation of naive CD4+ T cells into follicular helper T (Tfh) cells by activating coil domains containing 25 (CCDC25). Treatment with DNase I, which disrupts the structural integrity of EETs, or neutralizing antibody against CCDC25 reduced the expansion of Tfh cells and suppressed the production of autoantibodies in BP180-immunized BP-like mouse models. Additionally, we discovered that EETs induced the N6-methyladenosine methylation of the transcription factor musculoaponeurotic fibrosarcoma (MAF) via the DNA-CCDC25-VIRMA pathway, thereby enhancing its mRNA stability and promoting Tfh cell differentiation.

CONCLUSION

Our study revealed a previously unrecognized mechanism by which EETs trigger abnormal Tfh cell differentiation through CCDC25, followed by Vir-like m6A methyltransferase-associated protein (VIRMA)-mediated N6-methyladenosine modification of MAF. These insights provide promising avenues for the development of targeted therapeutic interventions in the field of BP and potentially other autoimmune diseases.

Saturated fatty acid-induced neutrophil extracellular traps contribute to exacerbation and biologic therapy resistance in obesity-related psoriasis

Psoriasis patients who are obese tend to have serious clinical manifestations and poor responses to various biological agents in most cases. However, the mechanisms by which obesity exacerbates psoriasis remain enigmatic. In this study, we found that the abundance of systemic and localized cutaneous neutrophil extracellular traps (NETs) associated with the obesity-induced aggravation of psoriasis was positively correlated with disease severity and that the inhibition of NETs alleviated psoriatic dermatitis in obese mice. Mechanistically, we found that changes in fatty acid composition in obese subjects resulted in the deposition of saturated fatty acids (SFAs), which promoted the release of NETs via the TLR4-MD2/ROS signaling pathway. We further revealed that NETs potentiate IL-17 inflammation, especially γδT17-mediated immune responses, in obesity-exacerbated psoriasis patients. Moreover, SFAs induced a decreased response to anti-IL17A treatment in psoriasis-like mice, whereas the inhibition of NETs improved the beneficial effects of anti-IL17A in psoriasis-like mice with lipid metabolism disorders. Our findings collectively suggest that SFA-induced NETs play a critical role in the exacerbation of obesity-related psoriasis and provide potential new strategies for the clinical treatment of refractory psoriasis patients with lipid metabolism disorders.

Neutrophil Extracellular Traps in Oral Diseases

OBJECTIVE

To summarize the current knowledge of the neutrophil extracellular traps (NETs) and its critical role in various oral diseases.

METHODS

We reviewed the recent research on NETs through PubMed and Web of Science. An analysis of recent research results was summarized from three aspects: NETs induction and formation, functions of NETs, and NETs in oral diseases.

RESULTS

The relationship between neutrophils and NETs is critical to the body's defense against microbial invasion. NETs can effectively combat pathogens with an anti-inflammatory effect and meanwhile it can contribute to inflammation. Moreover, it can synergize with other immune cells to respond to stimuli, such as pathogens, host-derived mediators, and drugs. It was revealed that NETs play different roles to influence various oral diseases like periodontitis, endodontic infection, oral mucosal diseases, maxillofacial tumors, and many other oral diseases.

CONCLUSION

The balance between the protective and potentially harmful effects of NETs is a key factor in determining the outcome of infections and inflammatory responses. The role of NETs in oral diseases needs to be further studied to enable better understanding of its role in the different oral diseases.

Multifunctional Boron-based 2D Nanoplatforms Ameliorate Severe Respiratory Inflammation by Targeting Multiple Inflammatory Mediators

Effective management of serious respiratory diseases, such as asthma and recalcitrant rhinitis, remains a global challenge. Here, it is shown that induced sputum supernatants (ISS) from patients with asthma contain higher levels of cell-free DNA (cfDNA) compared to that of healthy volunteers. Although cfDNA scavenging strategies have been developed for inflammation modulation in previous studies, this fall short in clinical settings due to the excessive neutrophil extracellular trap (NET) formation, reactive oxygen and nitrogen species (RONS) and bacterial infections in injured airway tissues. Based on this, a multifunctional boron-based 2D nanoplatform B-PM is designed by coating boron nanosheets (B-NS) with polyamidoamine generation 1 (PG1) dendrimer, which can simultaneously target cfDNA, NETs, RONS, and bacteria. The effects of B-PM in promoting mucosal repair, reducing airway inflammation, and mucus production have been demonstrated in model mice, and the therapeutic effect is superior to dexamethasone. Furthermore, flow cytometry with clustering analysis and transcriptome analysis with RNA-sequencing are adopted to comprehensively evaluate the in vivo anti-inflammation therapeutic effects. These findings emphasize the significance of a multi-targeting strategy to modulate dysregulated inflammation and highlight multifunctional boron-based 2D nanoplatforms for the amelioration of respiratory inflammatory diseases.

Conductive Hydrogel Inspires Neutrophil Extracellular Traps to Combat Bacterial Infections in Wounds

Thetreatment of infected wounds is currently a major challenge in clinical medicine, and enhancing antimicrobial and angiogenic capacity is one of the most common strategies. However, the current treatment makes it difficult to balance the antimicrobial effect in the early stage and the angiogenic effect in the later stages of wound healing, leading to an increased rate of poor prognosis. Here, we present a nanoconductive hydrogel EF@S-HGM, consisting of HGM with ECGS, FMLP, and SWCNT. The host-guest supramolecular macromolecule (HGM) hydrogel is biocompatible and can be injected in situ in the wound. The endothelial cell growth factor (ECGS) accelerates vascular remodeling and repairs wounds by promoting the proliferation of endothelial cells. N-Formyl-Met-Leu-Phe (FMLP) recruits neutrophils and increases the antimicrobial capacity. Single-walled carbon nanotubes (SWCNT) make the hydrogel conductive, enabling the hydrogel to utilize the endogenous electric field in the wound to recruit multiple kinds of cells. In addition, we found that the EF@S-HGM hydrogel activates the glucocorticoid receptor senescence pathway and promotes the formation of NET, which enhances the antimicrobial effect. As tissue-engineered skin, the conductive hydrogel EF@S-HGM is a promising material for regenerative medicine that may provide a potential option for the treatment and care of infected wounds and significantly improve patient outcomes and prognosis.

Fibrin aggravates periodontitis through inducing NETs formation from mitochondrial DNA

OBJECTIVES

This study investigated the role of fibrin on neutrophil extracellular traps (NETs) formation from neutrophils and to elucidate the involvement of mitochondria in NETs formation during periodontitis.

MATERIALS AND METHODS

Plasminogen-deficient (Plg-/-) mice were employed to evaluate the effects of fibrin deposition on inflammation, bone resorption, and neutrophil infiltration in periodontal tissues. In addition, in vitro tests evaluated fibrin's impact on neutrophil-driven inflammation. Mitochondrial reactive oxygen species (mtROS) levels within neutrophils were quantified utilizing flow cytometry and immunofluorescence in vitro. Furthermore, the anti-inflammatory properties of the mtROS scavenger, Mito-TEMPO, were confirmed to regulate the NET formation in vitro and in vivo.

RESULTS

Plasminogen deficiency resulted in increased fibrin deposition, neutrophil infiltration, inflammatory factors concentration, and alveolar bone resorption in periodontal tissues. After neutrophils were treated by fibrin in vitro, the expression of inflammatory factors, the formation of mtROS, and NETs enriched in mitochondrial DNA (mtDNA) were upregulated, which were reversed by Mito-TEMPO in vitro. Moreover, Mito-TEMPO alleviated inflammation in Plg-/- mice.

CONCLUSIONS

This study showed that fibrin deposition in gingiva induced the NET formation in Plg-/- mice, in which the DNA in NETs was from mitochondria depending on increasing mtROS.

The impact of aging on neutrophil functions and the contribution to periodontitis

The increasing aging population and aging-associated diseases have become a global issue for decades. People over 65 show an increased prevalence and greater severity of periodontitis, which poses threats to overall health. Studies have demonstrated a significant association between aging and the dysfunction of neutrophils, critical cells in the early stages of periodontitis, and their crosstalk with macrophages and T and B lymphocytes to establish the periodontal lesion. Neutrophils differentiate and mature in the bone marrow before entering the circulation; during an infection, they are recruited to infected tissues guided by the signal from chemokines and cytokines to eliminate invading pathogens. Neutrophils are crucial in maintaining a balanced response between host and microbes to prevent periodontal diseases in periodontal tissues. The impacts of aging on neutrophils' chemotaxis, anti-microbial function, cell activation, and lifespan result in impaired neutrophil functions and excessive neutrophil activation, which could influence periodontitis course. We summarize the roles of neutrophils in periodontal diseases and the aging-related impacts on neutrophil functional responses. We also explore the underlying mechanisms that can contribute to periodontitis manifestation in aging. This review could help us better understand the pathogenesis of periodontitis, which could offer novel therapeutic targets for periodontitis.

Causal relationship between 14 micronutrients and chronic periodontitis: a Mendelian randomization study

BACKGROUND

Chronic periodontitis is one of the most common inflammatory diseases worldwide. Micronutrients play a significant impact on health and periodontal disease progression. However, there is still a lack of conclusive studies confirming the causal association of micronutrients with chronic periodontitis.

MATERIALS AND METHODS

Genome-wide association study pooled data on chronic periodontitis were collected from the FinnGen consortium, and 14 micronutrients (calcium, copper, zinc, potassium, magnesium, selenium, iron, carotenoids, vitamin B6, B12, C, D, E and folate) were obtained from the OpenGWAS and UK Biobank Study. Instrumental variables were screened by strict criteria. Five Mendelian randomization (MR) methods were used. Finally, the robustness of the findings was verified by sensitivity analyses.

RESULTS

We found that vitamin D reduced the risk of chronic periodontitis (OR: 0.605, 95%CI: 0.398-0.921, P = 0.019). However, we had no evidence of a significant association between other micronutrients and chronic periodontitis. Multiple sensitivity analyses confirmed the robustness of the findings. A variety of sensitivity analysis methods confirmed the reliability of the results.

CONCLUSION

In this study, we found a potential causal relationship between vitamin D and chronic periodontitis by MR analysis, whereas we did not find an association between 13 other micronutrients and chronic periodontitis. This result might provide new ideas for the prevention and treatment of chronic periodontitis to some extent. However, despite the rigorous analytical methods used in this study, this finding needs to be interpreted with caution. Further randomized controlled studies might provide more in-depth references to the findings of this study.

Application of Nanomaterials Targeting Immune Cells in the Treatment of Chronic Inflammation

Chronic inflammation is a common characteristic of all kinds of diseases, including autoimmune diseases, metabolic diseases, and tumors. It is distinguished by the presence of low concentrations of inflammatory factors stimulating the body for an extended period, resulting in a persistent state of infection. This condition is manifested by the aggregation and infiltration of mononuclear cells, lymphocytes, and other immune cells, leading to tissue hyperplasia and lesions. Although various anti-inflammatory medications, including glucocorticoids and non-steroidal anti-inflammatory drugs (NSAIDs), have shown strong therapeutic effects, they lack specificity and targeting ability, and require high dosages, which can lead to severe adverse reactions. Nanoparticle drug delivery mechanisms possess the capacity to minimize the effect on healthy cells or tissues due to their targeting capabilities and sustained drug release properties. However, most nanosystems can only target the inflammatory sites rather than specific types of immune cells, leaving room for further improvement in the therapeutic effects of nanomaterials. This article reviews the current research progress on the role of diverse immune cells in inflammation, focusing on the functions of neutrophils and macrophages during inflammation. It provides an overview of the domestic and international applications of nanomaterials in targeted therapy for inflammation, aiming to establish a conceptual foundation for the utilization of nanomaterials targeting immune cells in the treatment of chronic inflammation and offer new perspectives for the avoidance and management of inflammation.

Dynamic Covalent Prodrug Nanonetworks via Reaction-Induced Self-Assembly for Periodontitis Treatment

Periodontitis is characterized by dysbiotic biofilms, gingival inflammation, and bone resorption, highlighting the urgent need for a comprehensive approach to drug combination therapy. In this study, we introduce dynamic covalent nanonetworks (dcNNWs) synthesized through a one-pot, four-component reaction-induced self-assembly method using polyamines, 2-formylphenylboronic acid, epigallocatechin gallate, and alendronate. The formation of iminoboronate bonds drives the creation of dcNNWs, allowing controlled release in the periodontitis microenvironment. The inclusion of catechol and bisphosphonate imparts exceptional bioadhesive properties to the dcNNWs, enhancing their efficacy in preventing pathogenic bacterial biofilm formation and eliminating mature biofilms. Moreover, the dcNNWs efficiently absorb pathogen-associated molecular patterns and scavenge excess reactive oxygen species, regulating the local immune response and demonstrating anti-inflammatory effects. Additionally, the released polyphenol and alendronate from the dcNNWs alleviated inflammation and enhanced osteogenesis significantly. The detailed synergistic effects of dcNNWs in biofilm eradication, anti-inflammation, and bone remodeling, with minimal impact on healthy tissues, are confirmed in a rat model of periodontitis. With a facile synthesis process, excellent synergistic effects in periodontitis treatment, and biocompatibility, our dcNNWs present a promising and translational solution for the effective management of periodontitis.

The translational potential of inflammation-induced skin blister human models in exploring the pathogenesis of periodontitis and its systemic health implications

Periodontitis is a highly prevalent chronic disease. Despite decades of extensive research on the topic, a complete understanding of its immunopathogenesis, especially when linked to other inflammatory comorbidities, is lacking. Ex vivo human and in vivo animal experiments have shown the host inflammatory response's crucial role in both the disease's onset and its systemic implications. These approaches, however, remain questionable when translating these findings into real-world scenarios linked to periodontitis. A clear need for new in vivo human models is discussed, especially within the context of understanding the host response to key pathogens linked to periodontitis, such as Porphyromonas gingivalis (P. gingivalis). Therefore, a skin blister model was employed to describe the stages of the host immune response in humans after challenges by microbial and/or sterile insults. A novel human challenge model using UV-killed P. gingivalis holds promise in producing new evidence and bridging the gap of the host response to periodontitis and its links with other common chronic diseases.

Optimizing collagen-based biomaterials for periodontal regeneration: clinical opportunities and challenges

Periodontal disease (PD) is a chronic inflammatory condition that affects the teeth and their supporting tissues, ultimately culminating in tooth loss. Currently, treatment modalities, such as systemic and local administration of antibiotics, serve to mitigate the progression of inflammation yet fall short in restoring the original anatomical structure and physiological function of periodontal tissues. Biocompatible material-based tissue engineering seems to be a promising therapeutic strategy for treating PD. Collagen, a component of the extracellular matrix commonly used for tissue engineering, has been regarded as a promising biogenic material for tissue regeneration owing to its high cell-activating and biocompatible properties. The structural and chemical similarities between collagen and components of the oral tissue extracellular matrix render it a promising candidate for dental regeneration. This review explored the properties of collagen and its current applications in periodontal regeneration. We also discussed the recent progression in collagen therapies and preparation techniques. The review also scrutinizes the pros and cons associated with the application of collagen-based biomaterials in PD treatment, aiming to pave the way for future applications of collagen-based biomaterials in the management of PD.

Neutrophils drive sexual dimorphism in experimental periodontitis

The motivating premise of this study is to improve the treatment of periodontal disease by elucidating sex-specific mechanisms of periodontal disease progression. Men and women experience inflammation in fundamentally different ways and understanding the sex-specific biology leading to inflammation and bone loss in the periodontium will inevitably improve patient outcomes. We therefore examined clinical and immunological differences in the progression of periodontal disease using the ligature-induced periodontitis model. Periodontitis was induced in male and female C57BL/6j mice by tying a 5-0 silk suture around the left maxillary second molar. The ligature was left on for 7 or 21 days at which point maxillae were characterized for bone loss by μCT or immune infiltrate by flow cytometry. Neutrophil depletion was accomplished through systemic administration of a Ly6G antibody. Conditions were compared using two-way ANOVA with Tukey's multiple comparison correction from n≥5 animals. Ligature-induced periodontitis led to alveolar bone loss at both 7 and 21 days in both female and male mice. Males and females had approximately the same amount of linear bone loss 7 days post-ligature placement, while male mice had significantly more linear bone loss by day 21. Male mice had significantly more immune cells in their maxillae 7 days post ligature placement compared to female mice. Both male and female mice showed a shift in immune populations towards neutrophils, with no significant difference between males and females. Neutrophil counts were significantly elevated in male mice on day 7 but not day 21, while female mice did not have any statistically significant changes in neutrophil counts. Neutrophil depletion using a Ly6G antibody limited bone loss in male but not female mice relative to isotype antibody-treated controls. Analysis of single-cell sequencing data from human patients with periodontitis showed differences in neutrophil phenotypes that were also observed in a mouse model of periodontitis. Together, these data suggest a mechanistic role for neutrophil inflammation in sexual dimorphism in periodontitis.

Hyperglycemia-Enhanced Neutrophil Extracellular Traps Drive Mucosal Immunopathology at the Oral Barrier

Type 2 diabetes (T2D) is a risk factor for mucosal homeostasis and enhances the susceptibility to inflammation, in which neutrophils have been increasingly appreciated for their role. Here, barrier disruption and inflammation are observed at oral mucosa (gingiva) of T2D patients and mice. It is demonstrated that neutrophils infiltrate the gingival mucosa of T2D mice and expel obvious neutrophil extracellular traps (NETs), while removal of NETs alleviates the disruption of mucosal barrier. Mechanistically, gingival neutrophils released NETs are dependent of their metabolic reprogramming. Under hyperglycemic condition, neutrophils elevate both glucose incorporation and glycolysis via increased expression of GLUT1. Moreover, significantly increased levels of NETs are observed in local gingival lesions of patients, which are associated with clinical disease severity. This work elucidates a causative link between hyperglycemia and oral mucosal immunopathology, mediated by the altered immuno-metabolic axis in neutrophil, thereby suggesting a potential therapeutic strategy.

Cellular senescence: A new perspective on the suppression of periodontitis (Review)

Cellular senescence, characterized by cell cycle arrest, can result in tissue dysfunction when senescent cells persist and accumulate. Periodontitis, a chronic inflammatory condition caused by the interaction between bacteria and the immune system of the host, primarily manifests as damage to periodontal tissues. Aging and inflammation are interlinked processes that exacerbate each other. The progression of localized chronic periodontal inflammation is often accelerated in conjunction with tissue and organ aging. The presence of senescent cells and release of inflammatory cytokines, immune modulators, growth factors and proteases that are associated with the senescence‑associated secretory phenotype contribute to the deterioration of periodontal tissues. The present review aimed to elucidate the mechanisms of cellular senescence and its potential impact on periodontitis, offering novel insights for modulating the inflammatory microenvironment of periodontal tissues.

The role of neutrophils in ANCA-associated vasculitis

Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a group of rare systemic autoimmune diseases characterised by necrotising inflammation of small blood vessels and usually associated with circulating ANCA. The pathophysiology of AAV is complex, involving many aspects of the innate and adaptive immune system. Neutrophils are central to the pathogenesis of AAV as they are both the target of the autoantibody and effector cells mediating vascular injury. We describe mechanisms for ANCA induced activation of neutrophils, the pathogenic mechanisms by which this leads to endothelial cell injury, and how neutrophil crosstalk modulates other aspects of the immune system in AAV.

ICAM1+ gingival fibroblasts modulate periodontal inflammation to mitigate bone loss

Tissue-resident fibroblasts are heterogeneous and provide an endogenous source of cytokines that regulate immunologic events in many osteolytic diseases. Identifying distinct inflammatory fibroblast subsets and conducting mechanistic in vivo studies are critical for understanding disease pathogenesis and precision therapeutics, which is poorly explored in periodontitis. Here, we surveyed published single-cell datasets for fibroblast-specific analysis and show that Intercellular Adhesion Molecule-1 (ICAM1) expression selectively defines a fibroblast subset that exhibits an inflammatory transcriptional profile associated with nuclear factor-κB (NF-κB) pathway. ICAM1+ fibroblasts expand in both human periodontitis and murine ligature-induced periodontitis model, which have upregulated expression of CCL2 and CXCL1 compared to other fibroblast populations. Using a mouse model to selectively target gingival stromal cells, we further show that disruption of an inflammatory pathway by inhibiting transcriptional activity of NF-κB in these cells accelerated periodontal bone loss. Mechanistically, this was linked to a reduction of CCL2 expression by the ICAM1+ fibroblasts, leading to impaired macrophage recruitment and efferocytosis that was associated with persistent neutrophilic inflammation. These results may have a significant therapeutic implication as ICAM1+ gingival fibroblasts exert a protective response by regulating innate immune responses that are needed for the controlled inflammatory events in early stages of periodontitis.

D-mannose alleviates chronic periodontitis in rats by regulating the functions of neutrophils

BACKGROUND

Periodontitis is a chronic inflammatory disease characterized by the destruction of the components of the periodontium. It significantly impacts oral health and has been linked to systemic conditions like cardiovascular disease and diabetes. The critical role of neutrophils in the occurrence and development of chronic periodontitis has been paid increasing attention. The study aimed to explore the protective effects of D-mannose on chronic periodontitis and determine whether its underlying mechanisms is related to neutrophils.

METHODS

To explore the protective effects of D-mannose on chronic periodontitis, the eight-week-old Sprague Dawley rat model of lipopolysaccharide (LPS)-induced periodontitis was established, followed by D-mannose treatment by oral gavage. To evaluate the protective effects of D-mannose against periodontal bone loss, methylene blue staining, hematoxylin and eosin (H&E) staining, and micro-CT scanning were utilized. Then, immunofluorescence (IF), Western Blot, and RT-PCR were applied to assess the expression levels of pro-inflammatory cytokines (IL-1β, IL-6, and IL-17), anti-inflammatory cytokine (IL-10), tumor necrosis factor-alpha (TNF-α), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), ten-eleven translocation 2 (TET2), and key glycolytic enzymes (HK1, HK2, PFKFB3), and to examine D-mannose's impact on the recruitment and activation of neutrophils in the gingiva. Additionally, neutrophils isolated from the peripheral blood of healthy rats were treated with LPS and D-mannose, and changes in the expression levels of myeloperoxidase (MPO), IL-1β, IL-6, IL-17, IL-10, and TET2 were observed via IF.

RESULTS

In vivo, D-mannose inhibited LPS-induced alveolar bone resorption in rats. After D-mannose treatment, the expression levels of IL-17 (p<0.01) and TET2 (p<0.01) were suppressed by IF, and the expression levels of IL-1β (p<0.05), IL-17 (p<0.05) and TET2 (p<0.01) were downregulated by WB. The results of qPCR showed that D-mannose reduced the expression levels of IL-1β (p<0.05), IL-6 (p<0.01), IL-17 (p<0.01), TNF-α (p<0.01), G-CSF (p<0.01), GM-CSF (p<0.01), TET2 (p<0.01), HK1 (p<0.01), HK2 (p<0.01), and PFKFB3 (p<0.01). D-mannose also inhibited the recruitment and activation of neutrophils in LPS-treated rat gingival tissues. In vitro, the results of IF showed that D-mannose inhibited the activation of neutrophils stimulated by LPS, downregulated the expression of IL-1β (p < 0.05), IL-6, IL-17 (p < 0.01), and TET2 (p < 0.01), and upregulated the expression of IL-10 (p < 0.01).

CONCLUSIONS

D-mannose can alleviate chronic periodontitis in rats by regulating the functions of neutrophils, potentially associated with the expression of TET2 and glycolysis, providing new insights into the potential application of D-mannose to chronic periodontitis.

Expression of neutrophil extracellular trap-related proteins and its correlation with IL-17 and TNF-α in patients with oral lichen planus

Background

Neutrophil extracellular traps (NETs) are produced by polymorphonuclear neutrophils (PMNs) stimulated by interleukin-17 (IL-17) and tumor necrosis factor α (TNF-α). However, the level and role of NETs in oral lichen planus (OLP) remain poorly understood.

Objective

This study aimed to investigate the expression of NETs in OLP and explore the correlation between NETs and the levels of IL-17 and TNF-α.

Methods

The expression and distribution of NET-related proteins in tissue samples from each group were assessed using hematoxylin-eosin (HE) staining and immunofluorescence (IF). Additionally, the expression of NET-related proteins in peripheral blood samples from each group was evaluated using cell IF technique and fluorescence spectrophotometry. The relative formation level of NETs in each group was determined by fluorescence spectrophotometry via plasma co-culture. Furthermore, the levels of inflammatory cytokines IL-17 and TNF-α in plasma and culture supernatant were measured using enzyme-linked immunosorbent assay (ELISA).

Results

NET-related proteins were located in the subepithelial and lamina propria layers of OLP lesions. OLP had significantly higher expression of NET-related proteins in lesion tissues and peripheral blood compared to the healthy control (HC) group (p < 0.05). The rate of NETs formation in the erosive-stage OLP (EOLP) group was significantly higher than that in the HC group (p < 0.05), in contrast, no significant increase was observed in the non-erosive OLP (NEOLP) group (p > 0.05). Furthermore, the levels of IL-17 and TNF-α in the EOLP group were significantly elevated compared to those in the NEOLP group and HC group (p < 0.05), while the levels in the NEOLP group did not significantly differ from those in the HC group (p > 0.05). The rate of NETs formation showed a positive correlation with the levels of IL-17 and TNF-α in plasma.

Conclusion

The expression of NET-related proteins was upregulated in OLP lesion tissues and peripheral blood. Elevated levels of IL-17 and TNF-α in peripheral blood plasma positively correlated with the rate of NETs formation, suggesting that IL-17 and TNF-α mediate the formation of NETs in OLP patients, and may thereby contribute to the development of OLP.

Kinetics of neutrophil extracellular traps and cytokines in oral mucositis and Candida infection

OBJECTIVE

This study investigated the concentrations of neutrophil extracellular traps (NET) and salivary cytokines (IL-1β, IL-6, IL-8/CXCL8, TNF, and TGF-β1) in patients undergoing chemotherapy and their associations with oral mucositis (OM) and Candida infection.

MATERIALS AND METHODS

This prospective longitudinal study performed at a Brazilian service included 60 adults diagnosed with hematolymphoid diseases. Saliva samples were collected on days D0, D3, D10, and D15. Cytokines were analyzed by ELISA and NET formation by identification of the myeloperoxidase-DNA complex. Oral Candida spp. was cultured.

RESULTS

OM occurred in 43.3% of patients and oral candidiasis in 20%. However, 66% of individuals had positive cultures for C. albicans. Higher concentrations of IL-6, IL-8/CXCL8, and TNF and lower concentrations of TGF-β1 were observed in patients with OM. C. albicans infection contributed to the increase in IL-8/CXCL8, TGF-β1, and TNF. Individuals with OM or with oral candidiasis had significant reductions in NET formation. In contrast, individuals with C. albicans and with concomitant C. albicans and OM exhibited higher NET formation.

CONCLUSION

The kinetics of cytokine levels and NET formation in chemotherapy-induced OM appears to be altered by Candida infection, even in the absence of clinical signs of oral candidiasis.

Pyroptosis: A major trigger of excessive immune response in the gingiva

OBJECTIVES

The gingival mucosal barrier, an important oral cavity barrier, plays a significant role in preventing pathogenic microorganism invasion and maintaining periodontal tissue health. Pathogenic microorganism invasion of the gingival mucosa produces a large number of cytokines. Among them, pyroptosis is an important player in exacerbating immune-inflammatory responses, leading to tissue destruction. However, the mechanism of pyroptosis and the immune response it triggers have not been fully elucidated. We provide an overview of recent advances in understanding gingival physical barrier pyroptosis and inflammation-induced hyperimmunity.

METHODS

PubMed, Web of Science databases were searched for articles, reviews, and clinical studies published until March 2024.

RESULTS

We summarised the importance of the gingival barrier in terms of the functions of different cells, described the progress in research on gingival epithelial cell and gingival fibroblast pyroptosis and the immune-inflammatory response it induces, and discussed the relationship between pyroptosis and systemic diseases, association of multiple cell death systems. Finally, we propose future directions for pyroptosis research.

CONCLUSIONS

Pyroptosis often triggers a range of inflammatory immune responses that lead to associated diseases. Therefore, further study of the molecular mechanisms of pyroptosis and the immune responses is warranted.

Bite-sized immunology; damage and microbes educating immunity at the gingiva

Immune cells residing at the gingiva experience diverse and unique signals, tailoring their functions to enable them to appropriately respond to immunological challenges and maintain tissue integrity. The gingiva, defined as the mucosal barrier that surrounds and supports the teeth, is the only barrier site completely transected by a hard structure, the tooth. The tissue is damaged in early life during tooth eruption and chronically throughout life by the process of mastication. This occurs alongside challenges typical of barrier sites, including exposure to invading pathogens, the local commensal microbial community and environmental antigens. This review will focus on the immune network safeguarding gingival integrity, which is far less understood than that resident at other barrier sites. A detailed understanding of the gingiva-resident immune network is vital as it is the site of the inflammatory disease periodontitis, the most common chronic inflammatory condition in humans which has well-known detrimental systemic effects. Furthering our understanding of how the immune populations within the gingiva develop, are tailored in health, and how this is dysregulated in disease would further the development of effective therapies for periodontitis.

Association between high-density lipoprotein-related inflammation index and periodontitis: insights from NHANES 2009-2014

BACKGROUND

Periodontitis, a persistent inflammatory condition, significantly impairs individuals' overall quality of life. Lymphocyte-to-high-density lipoprotein cholesterol ratio (LHR), monocyte-to-high-density lipoprotein cholesterol ratio (MHR), neutrophil-to-high-density lipoprotein cholesterol ratio (NHR), and platelet-to-high-density lipoprotein cholesterol ratio (PHR) are new convenient and economical biomarkers. However, whether the above high-density lipoprotein-related inflammatory biomarkers are associated with periodontitis has rarely been investigated. Therefore, the research endeavor focused on uncovering potential relationships.

METHODS

The research encompassed a diverse and extensive sample, comprising 9,470 participants, selected from the National Health and Nutrition Examination Survey spanning the years 2009 to 2014. The association between high-density lipoprotein-related inflammatory biomarkers and periodontitis was explored utilizing a multivariable logistic regression model with weighted analysis. Additionally, the study employed smoothed curve fitting to explore potential nonlinear relationships. Further stratified analyses and interaction tests were performed.

RESULTS

This study indicated no apparent association between MHR and PHR with periodontitis, whereas LHR and NHR demonstrated a statistically significant positive relationship with the prevalence of periodontitis. In the fully adjusted model, participants belonging to the highest tertile of both LHR and NHR showed a notably higher likelihood of having periodontitis compared to those in the lowest tertile (LHR: OR = 1.22, 95% CI: 1.06, 1.39; NHR: OR = 1.27, 95% CI: 1.09, 1.49). Furthermore, smooth curve fitting was employed to investigate the potential nonlinear relationship between LHR, NHR, and periodontitis. The results indicated that there was a significant increase in the occurrence of periodontitis when Log2 (LHR) exceeded 1.01 and Log2(NHR) surpassed 2.16 (Log2(LHR): OR = 1.42; 95% CI: 1.19, 1.69; Log2(NHR): OR = 1.40; 95% CI: 1.15, 1.71). The subgroup analysis revealed that the associations between periodontitis and either LHR or NHR, separately, were more pronounced among individuals under the age of 50 and those without hypertension.

CONCLUSIONS

This cross-sectional study revealed a positive relationship between LHR、NHR and periodontitis, particularly when these indicators exceeded their thresholds. LHR and NHR may serve as potential inflammatory markers for identifying periodontitis, thereby facilitating early warning for both patients and dentists, and enabling early intervention in the oral environment. Besides, extensive prospective cohort investigations are essential to confirm and solidify this observation.

Roles of Toll-like Receptor Signaling in Inflammatory Bone Resorption

Toll-like receptors (TLRs) are pattern recognition receptors expressed in immune cells, including neutrophils, macrophages, and dendritic cells. Microbe-associated molecular patterns, including bacterial components, membranes, nucleic acids, and flagella are recognized by TLRs in inflammatory immune responses. Periodontal disease is an inflammatory disease known to cause local infections associated with gingival inflammation, subsequently leading to alveolar bone resorption. Prostaglandin E2 (PGE2) is a key mediator of TLR-induced inflammatory bone resorption. We previously reported that membrane-bound PGE synthase (mPGES-1)-deficient mice failed to induce bone resorption by lipopolysaccharide (LPS), a major pathogenic factor involved in periodontal bone resorption. Further experiments exploring specific pathogen-promoting osteoclast differentiation revealed that various TLR ligands induced osteoclast differentiation in a co-culture model. The ligands for TLR2/1, TLR2/6, TLR3, and TLR5, as well as TLR4, induce osteoclast differentiation associated with the production of PGE2 and the receptor activator of nuclear factor-kappa B ligand (RANKL), an inevitable inducer of osteoclast differentiation in osteoblasts. In vivo, local injection of TLR ligands, including TLR2/1, TLR2/6, and TLR3, resulted in severe alveolar bone resorption. This review summarizes the latest findings on TLR-mediated osteoclast differentiation and bone resorption in inflammatory diseases, such as periodontal diseases.

Cytokines in gingivitis and periodontitis: from pathogenesis to therapeutic targets

Chronic inflammatory processes in the oral mucosa and periodontitis are common disorders caused by microflora and microbial biofilms. These factors activate both the innate and adaptive immune systems, leading to the production of pro-inflammatory cytokines. Cytokines are known to play a crucial role in the pathogenesis of gingivitis and periodontitis and have been proposed as biomarkers for diagnosis and follow-up of these diseases. They can activate immune and stromal cells, leading to local inflammation and tissue damage. This damage can include destruction of the periodontal ligaments, gingiva, and alveolar bone. Studies have reported increased local levels of pro-inflammatory cytokines, such as interleukin-1beta (IL-1beta), tumor necrosis factor (TNF), IL-6, IL-17, and IL-23, in patients with periodontitis. In experimental models of periodontitis, TNF and the IL-23/IL-17 axis play a pivotal role in disease pathogenesis. Inactivation of these pro-inflammatory pathways through neutralizing antibodies, genetic engineering or IL-10 function has been demonstrated to reduce disease activity. This review discusses the role of cytokines in gingivitis and periodontitis, with particular emphasis on their role in mediating inflammation and tissue destruction. It also explores new therapeutic interventions that offer potential for research and clinical therapy in these chronic inflammatory diseases.

Emerging therapeutic strategies targeting extracellular histones for critical and inflammatory diseases: an updated narrative review

Extracellular histones are crucial damage-associated molecular patterns involved in the development and progression of multiple critical and inflammatory diseases, such as sepsis, pancreatitis, trauma, acute liver failure, acute respiratory distress syndrome, vasculitis and arthritis. During the past decade, the physiopathologic mechanisms of histone-mediated hyperinflammation, endothelial dysfunction, coagulation activation, neuroimmune injury and organ dysfunction in diseases have been systematically elucidated. Emerging preclinical evidence further shows that anti-histone strategies with either their neutralizers (heparin, heparinoids, nature plasma proteins, small anion molecules and nanomedicines, etc.) or extracorporeal blood purification techniques can significantly alleviate histone-induced deleterious effects, and thus improve the outcomes of histone-related critical and inflammatory animal models. However, a systemic evaluation of the efficacy and safety of these histone-targeting therapeutic strategies is currently lacking. In this review, we first update our latest understanding of the underlying molecular mechanisms of histone-induced hyperinflammation, endothelial dysfunction, coagulopathy, and organ dysfunction. Then, we summarize the latest advances in histone-targeting therapy strategies with heparin, anti-histone antibodies, histone-binding proteins or molecules, and histone-affinity hemoadsorption in pre-clinical studies. Finally, challenges and future perspectives for improving the clinical translation of histone-targeting therapeutic strategies are also discussed to promote better management of patients with histone-related diseases.

The emerging role of neutrophil extracellular traps in ulcerative colitis

Ulcerative colitis (UC) is characterized by chronic non-recessive inflammation of the intestinal mucosa involving both innate and adaptive immune responses. Currently, new targeted therapies are urgently needed for UC, and neutrophil extracellular traps (NETs) are new therapeutic options. NETs are DNA-based networks released from neutrophils into the extracellular space after stimulation, in which a variety of granule proteins, proteolytic enzymes, antibacterial peptides, histones, and other network structures are embedded. With the deepening of the studies on NETs, their regulatory role in the development of autoimmune and autoinflammatory diseases has received extensive attention in recent years. Increasing evidence indicates that excess NETs exacerbate the inflammatory response in UC, disrupting the structure and function of the intestinal mucosal barrier and increasing the risk of thrombosis. Although NETs are usually assigned a deleterious role in promoting the pathological process of UC, they also appear to have a protective role in some models. Despite such progress, comprehensive reviews describing the therapeutic promise of NETs in UC remain limited. In this review, we discuss the latest evidence for the formation and degradation of NETs, focusing on their double-edged role in UC. Finally, the potential implications of NETs as therapeutic targets for UC will be discussed. This review aims to provide novel insights into the pathogenesis and therapeutic options for UC.

CXCR4-mediated neutrophil dynamics in periodontitis

BACKGROUND AND OBJECTIVE

Periodontitis is a common oral disease closely related to immune response and this study is aimed to identify the key immune-related pathogenic genes and analyze the infiltration and function of immune cells in the disease using bioinformatics methods.

METHODS

Transcriptome datasets and single-cell RNA sequencing (scRNA-seq) datasets were downloaded from the GEO database. We utilized weighted correlation network analysis and least absolute selection and shrinkage operator, protein-protein interaction network construction to screen out key pathogenic genes as well as conducted the cell-type identification by estimating relative subsets of RNA transcripts algorithm to analyze and characterize immune cell types in periodontal tissues. In addition to bioinformatics validations, clinical and cell samples were collected and mouse periodontitis models were constructed to validate the important role of key genes in periodontitis.

RESULTS

Bioinformatics analysis pointed out the positive correlation between CXCR4 expression and periodontitis, and revealed the increased infiltration of neutrophils in periodontal inflammatory. Similar results were obtained from clinical samples and animal models. In addition, the clustering and functional enrichment results based on CXCR4 expression levels included activation of immune response and cell migration, implying the possible function of CXCR4 on regulating neutrophil dynamics, which might contribute to periodontitis. Subsequent validation experiments confirmed that the increased expression of CXCR4 in neutrophils under periodontitis, where cell migration-related pathways also were activated.

CONCLUSION

CXCR4 could be the key pathogenic gene of periodontitis and CXCR4/CXCL12 signal axial might contribute to the development of periodontitis by mediating neutrophil dynamics, suggesting that CXCR4 could be a potential target to help identify novel strategies for the clinical diagnosis and treatment of periodontitis.

The bidirectional effect of neutrophils on periodontitis model in mice: A systematic review

OBJECTIVE

To evaluate the regulatory role of neutrophils as the first line of host immune defense in the periodontal microenvironment of mice.

METHODS

A systematic search was performed using PubMed, Web of Science, and ScienceDirect databases for articles published between 2012 and 2023. In this review, articles investigating the effect of neutrophils on alveolar bone resorption in a mouse model of periodontitis were selected and evaluated according to eligibility criteria. Important variables that may influence outcomes were analyzed.

RESULTS

Eleven articles were included in this systematic review. The results showed that because of their immune defense functions, the functional homeostasis of local neutrophils is critical for periodontal health. Neutrophil deficiency aggravates alveolar bone loss. However, several studies have shown that excessive neutrophil infiltration is positively correlated with alveolar bone resorption caused by periodontitis in mice. Therefore, the homeostasis of neutrophil function needs to be considered in the treatment of periodontitis.

CONCLUSIONS

Pooled analysis suggests that neutrophils play a bidirectional role in periodontal tissue remodeling in mouse periodontitis models. Therefore, targeted regulation of local neutrophil function provides a novel strategy for the treatment of periodontitis.

Targeting extranuclear histones to alleviate acute and chronic inflammation

Extracellular histones instigate an inflammatory triad - centered on cytotoxicity, immune cell stimulation, and coagulation - ultimately shaping the dynamics and outcome of various inflammatory pathologies. Given the virtual absence of beneficial functions of histones in the extracellular space, in recent years a number of interference strategies have emerged. In this review we summarize pathogenic functions of extracellular histones and highlight current developments of therapeutic interference. Finally, we elaborate on the current status of preclinical attempts to interfere with extracellular histones in the context of a focus on sepsis and cardiovascular diseases, both of which are leading causes of mortality worldwide.

The peculiar features, diversity and impact of citrulline-reactive autoantibodies

Since entering the stage 25 years ago as a highly specific serological biomarker for rheumatoid arthritis, anti-citrullinated protein antibodies (ACPAs) have been a topic of extensive research. This hallmark B cell response arises years before disease onset, displays interpatient autoantigen variability, and is associated with poor clinical outcomes. Technological and scientific advances have revealed broad clonal diversity and intriguing features including high levels of somatic hypermutation, variable-domain N-linked glycosylation, hapten-like peptide interactions, and clone-specific multireactivity to citrullinated, carbamylated and acetylated epitopes. ACPAs have been found in different isotypes and subclasses, in both circulation and tissue, and are secreted by both plasmablasts and long-lived plasma cells. Notably, although some disease-promoting features have been reported, results now demonstrate that certain monoclonal ACPAs therapeutically block arthritis and inflammation in mouse models. A wealth of functional studies using patient-derived polyclonal and monoclonal antibodies have provided evidence for pathogenic and protective effects of ACPAs in the context of arthritis. To understand the roles of ACPAs, one needs to consider their immunological properties by incorporating different facets such as rheumatoid arthritis B cell biology, environmental triggers and chronic antigen exposure. The emerging picture points to a complex role of citrulline-reactive autoantibodies, in which the diversity and dynamics of antibody clones could determine clinical progression and manifestations.

Advances in Hydrogels for Periodontitis Treatment

Periodontitis is a common condition characterized by a bacterial infection and the disruption of the body's immune-inflammatory response, which causes damage to the teeth and supporting tissues and eventually results in tooth loss. Current therapy involves the systemic and local administration of antibiotics. However, the existing treatments cannot exert effective, sustained release and maintain an effective therapeutic concentration of the drug at the lesion site. Hydrogels are used to treat periodontitis due to their low cytotoxicity, exceptional water retention capability, and controlled drug release profile. Hydrogels can imitate the extracellular matrix of periodontal cells while offering suitable sites to load antibiotics. This article reviews the utilization of hydrogels for periodontitis therapy based on the pathogenesis and clinical manifestations of the disease. Additionally, the latest therapeutic strategies for smart hydrogels and the main techniques for hydrogel preparation have been discussed. The information will aid in designing and preparing future hydrogels for periodontitis treatment.

Neutrophils and neutrophil extracellular traps in oral health and disease

Neutrophils perform essential functions in antimicrobial defense and tissue maintenance at mucosal barriers. However, a dysregulated neutrophil response and, in particular, the excessive release of neutrophil extracellular traps (NETs) are implicated in the pathology of various diseases. In this review, we provide an overview of the basic concepts related to neutrophil functions, including NET formation, and discuss the mechanisms associated with NET activation and function in the context of the prevalent oral disease periodontitis.

C-TYPE LECTIN-2D RECEPTOR CONTRIBUTES TO HISTONE-INDUCED VASCULAR BARRIER DYSFUNCTION DURING BURN INJURY

ABSTRACT

Severe burns are associated with massive tissue destruction and cell death where nucleus histones and other damage-associated molecular patterns are released into the circulation and contribute to the pathogenesis of multiple-organ dysfunction. Currently, there is limited information regarding the pathophysiology of extracellular histones after burns, and the mechanisms underlying histone-induced vascular injury are not fully understood. In this study, by comparing the blood samples from healthy donors and burn patients, we confirmed that burn injury promoted the release of extracellular histones into the circulation, evidenced by increased plasma levels of histones correlating with injury severity. The direct effects of extracellular histones on human endothelial monolayers were examined, and the results showed that histones caused cell-cell adherens junction discontinuity and barrier dysfunction in a dose-related manner. Like burn patients, mice subjected to a scald burn covering 25% total body surface area also displayed significantly increased plasma histones. Intravital microscopic analysis of mouse mesenteric microcirculation indicated that treatment with a histone antibody greatly attenuated burn-induced plasma leakage in postcapillary venules, supporting the pathogenic role of extracellular histones in the development of microvascular barrier dysfunction during burns. At the molecular level, intrigued by the recent discovery of C-type lectin domain family 2 member D (Clec2d) as a novel receptor of histones, we tested its potential involvement in the histone interaction with endothelial cells. Indeed, we identified abundant expression of Clec2d in vascular endothelial cells. Further proximity ligation assay demonstrated a close association between extracellular histones and endothelial expressing Clec2d. Functionally, in vivo administration of an anti-Clec2d antibody attenuated burn-induced plasma leakage across mesenteric microvessels. Consistently, Clec2d knockdown in endothelial cells partially inhibited histone-induced endothelial barrier dysfunction. Together, our data suggest that burn injury-induced increases in circulating histones contribute to microvascular leakage and endothelial barrier dysfunction via a mechanism involving the endothelial Clec2d receptor.

IL-36 Regulates Neutrophil Chemotaxis and Bone Loss at the Oral Barrier

Tissue-specific mechanisms regulate neutrophil immunity at the oral barrier, which plays a key role in periodontitis. Although it has been proposed that fibroblasts emit a powerful neutrophil chemotactic signal, how this chemotactic signal is driven has not been clear. The objective of this study was to investigate the site-specific regulatory mechanisms by which fibroblasts drive powerful neutrophil chemotactic signals within the oral barrier, with particular emphasis on the role of the IL-36 family. The present study found that IL-36γ, agonist of IL-36R, could promote neutrophil chemotaxis via fibroblast. Single-cell RNA sequencing data disclosed that IL36G is primarily expressed in human and mouse gingival epithelial cells and mouse neutrophils. Notably, there was a substantial increase in IL-36γ levels during periodontitis. In vitro experiments demonstrated that IL-36γ specifically activates gingival fibroblasts, leading to chemotaxis of neutrophils. In vivo experiments revealed that IL-36Ra inhibited the infiltration of neutrophils and bone resorption, while IL-36γ promoted their progression in the ligature-induced periodontitis mouse model. In summary, these data elucidate the function of the site-enriched IL-36γ in regulating neutrophil immunity and bone resorption at the oral barrier. These findings provide new insights into the tissue-specific pathophysiology of periodontitis and offer a promising avenue for prevention and treatment through targeted intervention of the IL-36 family.

Neutrophils in Inflammatory Bone Diseases

PURPOSE OF REVIEW

In this review, we summarize the current evidence that suggests that neutrophils play a key role in facilitating damage to local bone structures.

RECENT FINDINGS

Neutrophil infiltration is a hallmark of inflammatory bone diseases such as rheumatoid arthritis (RA) and periodontitis disease (PD). Both of these human diseases are marked by an imbalance in bone homeostasis, favoring the degradation of local bone which ultimately leads to erosions. Osteoclasts, a multinucleated resident bone cell, are responsible for facilitating the turnover of bone and the bone damage observed in these diseases. The involvement of neutrophils and neutrophil extracellular trap formation have recently been implicated in exacerbating osteoclast function through direct and indirect mechanisms. We highlight a recent finding that NET proteins such as histones and elastase can generate non-canonical, inflammatory osteoclasts, and this process is mediated by post-translational modifications such as citrullination and carbamylation, both of which act as autoantigens in RA. It appears that NETs, autoantibodies, modified proteins, cytokines, and osteoclasts all ultimately contribute to local and permanent bone damage in RA and PD. However, more studies are needed to fully understand the role of neutrophils in inflammatory bone diseases.

Salicin alleviates periodontitis via Tas2r143/gustducin signaling in fibroblasts

Introduction

Cells expressing taste signaling elements in non-gustatory tissues have been described as solitary chemosensory cells (SCCs) or tuft cells. These "taste-like" cells play a critical role in the maintenance of tissue homeostasis. Although the expression of SCC markers and taste signaling constituents has been identified in mouse gingivae, their role in periodontal homeostasis is still unclear.

Methods

Public RNA sequencing datasets were re-analyzed and further validated with RT-PCR/qRT-PCR and immunofluorescent staining to explore the expression of TAS2Rs and downstream signaling constituents in mouse gingival fibroblasts (MGFs). The specific action of salicin on MGFs via Tas2r143 was validated with RNA silence, heterologous expression of taste receptor/Gα-gustducin and calcium imaging. The anti-inflammatory effects of salicin against LPS-induced MGFs were investigated in cell cultures, and were further validated with a ligature-induced periodontitis mouse model using Ga-gustducin-null (Gnat3-/-) mice.

Results

The expression of Tas2r143, Gnat3, Plcb2, and TrpM5 was detected in MGFs. Moreover, salicin could activate Tas2r143, elicited taste signaling and thus inhibited LPS-induced chemokines expression (CXCL1, CXCL2, and CXCL5) in MGFs. Consistently, salicin-treatment inhibited periodontal bone loss, inflammatory/chemotactic factors expression, and neutrophil infiltration in periodontitis mice, while these effects were abolished in Gnat3-/- mice.

Discussion

Gingival fibroblasts play a critical role in the maintenance of periodontal homeostasis via "SCC-like" activity. Salicin can activate Tas2r143-mediated bitter taste signaling and thus alleviate periodontitis in mouse, indicating a promising approach to the resolution of periodontal inflammation via stimulating the "SCC-like" function of gingival fibroblasts.

The neutrophil-osteogenic cell axis promotes bone destruction in periodontitis

The immune-stromal cell interactions play a key role in health and diseases. In periodontitis, the most prevalent infectious disease in humans, immune cells accumulate in the oral mucosa and promote bone destruction by inducing receptor activator of nuclear factor-κB ligand (RANKL) expression in osteogenic cells such as osteoblasts and periodontal ligament cells. However, the detailed mechanism underlying immune-bone cell interactions in periodontitis is not fully understood. Here, we performed single-cell RNA-sequencing analysis on mouse periodontal lesions and showed that neutrophil-osteogenic cell crosstalk is involved in periodontitis-induced bone loss. The periodontal lesions displayed marked infiltration of neutrophils, and in silico analyses suggested that the neutrophils interacted with osteogenic cells through cytokine production. Among the cytokines expressed in the periodontal neutrophils, oncostatin M (OSM) potently induced RANKL expression in the primary osteoblasts, and deletion of the OSM receptor in osteogenic cells significantly ameliorated periodontitis-induced bone loss. Epigenomic data analyses identified the OSM-regulated RANKL enhancer region in osteogenic cells, and mice lacking this enhancer showed decreased periodontal bone loss while maintaining physiological bone metabolism. These findings shed light on the role of neutrophils in bone regulation during bacterial infection, highlighting the novel mechanism underlying osteoimmune crosstalk.

Pre-Analytical Factors Affecting Extracellular DNA in Saliva

Salivary DNA is widely used for genetic analyses because of its easy collection. However, its extracellular fraction in particular, similar to the extracellular DNA (ecDNA) in plasma, could be a promising biomarker for oral or systemic diseases. In contrast to genetics, the quantity of salivary ecDNA is of importance and can be affected by the pre-analytical processing of samples, but the details are not known. The aim of our study was to analyze the effects of centrifugation and freezing of saliva on the concentration of ecDNA in saliva. Fifteen healthy volunteers, free of any known systemic or oral diseases, were asked to collect unstimulated saliva samples. Aliquots were centrifuged at 1600× g and frozen or directly processed. The fresh or thawed cell-free saliva samples underwent subsequent centrifugation at 16,000× g. The supernatants were used for DNA isolation and quantification using fluorometry and real-time PCR. While freezing had minimal effects on the salivary ecDNA concentration, another centrifugation step decreased ecDNA considerably in both fresh and frozen samples (by 97.8% and 98.4%, respectively). This was mirrored in the quantitative PCR targeting a nuclear (decrease by 93.5%) and mitochondrial (decrease by 97.7%) ecDNA sequence. In conclusion, in this first study focusing on the technical aspects of salivary ecDNA quantitation, we show that, regardless of its subcellular origin, the concentration of ecDNA in saliva is mainly affected by additional centrifugation and not by the freezing of centrifuged cell-free saliva samples. This suggests that most salivary ecDNA likely is associated with cell debris and apoptotic bodies. Which fraction is affected by a particular disease should be the focus of further targeted studies.

Extracellular DNA and Markers of Neutrophil Extracellular Traps in Saliva from Patients with Periodontitis-A Case-Control Study

Periodontitis is a chronic inflammatory disease. We have previously shown that salivary DNA is higher in patients with periodontitis. Neutrophil extracellular traps (NETs) are involved in the pathogenesis of chronic inflammatory diseases. The objective of this case-control study was to compare patients with periodontitis and healthy controls regarding the salivary concentrations of extracellular DNA and NET components. Unstimulated saliva samples were collected from 49 patients with periodontitis and 71 controls before an oral examination. Salivary extracellular DNA was isolated and quantified fluorometrically and using PCR. NET-associated markers were assessed using ELISA. We have found significantly higher concentrations of salivary extracellular DNA in samples from periodontitis patients (five-times higher for supernatant and three times for pellet). Our results show that patients also have three-times-higher salivary nucleosomes and NET-associated enzymes-myeloperoxidase and neutrophil elastase (both two-times higher). Neutrophil elastase and salivary DNA in the pellet correlated positively with the pocket depth/clinical attachment level in periodontitis patients (r = 0.31-weak correlation; p = 0.03 and r = 0.41-moderate correlation, p = 0.004). Correlations between salivary extracellular DNA and NET enzymes were positive and significant. Based on our results, the higher salivary extracellular DNA in periodontitis seems to be related to components of NETs, albeit with weak to moderate correlations indicating that NETs are produced in periodontitis and can play a role in its pathogenesis similarly to other inflammatory diseases. Further studies should prove this assumption with potential diagnostic and therapeutic consequences.

Neutrophils' Contribution to Periodontitis and Periodontitis-Associated Cardiovascular Diseases

Neutrophils represent the primary defense against microbial threats playing a pivotal role in maintaining tissue homeostasis. This review examines the multifaceted involvement of neutrophils in periodontitis, a chronic inflammatory condition affecting the supporting structures of teeth summarizing the contribution of neutrophil dysfunction in periodontitis and periodontal-related comorbidities. Periodontitis, a pathological condition promoted by dysbiosis of the oral microbiota, is characterized by the chronic inflammation of the gingiva and subsequent tissue destruction. Neutrophils are among the first immune cells recruited to the site of infection, releasing antimicrobial peptides, enzymes, and reactive oxygen species to eliminate pathogens. The persistent inflammatory state in periodontitis can lead to aberrant neutrophil activation and a sustained release of proinflammatory mediators, finally resulting in tissue damage, bone resorption, and disease progression. Growing evidence now points to the correlation between periodontitis and systemic comorbidities. Indeed, the release of inflammatory mediators, immune complexes, and oxidative stress by neutrophils, bridge the gap between local and systemic immunity, thus highlighting neutrophils as key players in linking periodontal inflammation to chronic conditions, including cardiovascular diseases, diabetes mellitus, and rheumatoid arthritis. This review underscores the crucial role of neutrophils in the pathogenesis of periodontitis and the complex link between neutrophil dysfunction, local inflammation, and systemic comorbidities. A comprehensive understanding of neutrophil contribution to periodontitis development and their impact on periodontal comorbidities holds significant implications for the management of oral health. Furthermore, it highlights the need for the development of novel approaches aimed at limiting the persistent recruitment and activation of neutrophils, also reducing the impact of periodontal inflammation on broader health contexts, offering promising avenues for improved disease management and patient care.