Inflamm-Aging-Related Cytokines of IL-17 and IFN-γ Accelerate Osteoclastogenesis and Periodontal Destruction

A new direction in periodontitis treatment: biomaterial-mediated macrophage immunotherapy

Periodontitis is a chronic inflammation caused by a bacterial infection and is intimately associated with an overactive immune response. Biomaterials are being utilized more frequently in periodontal therapy due to their designability and unique drug delivery system. However, local and systemic immune response reactions driven by the implantation of biomaterials could result in inflammation, tissue damage, and fibrosis, which could end up with the failure of the implantation. Therefore, immunological adjustment of biomaterials through precise design can reduce the host reaction while eliminating the periodontal tissue's long-term chronic inflammation response. It is important to note that macrophages are an active immune system component that can participate in the progression of periodontal disease through intricate polarization mechanisms. And modulating macrophage polarization by designing biomaterials has emerged as a new periodontal therapy technique. In this review, we discuss the role of macrophages in periodontitis and typical strategies for polarizing macrophages with biomaterials. Subsequently, we discuss the challenges and potential opportunities of using biomaterials to manipulate periodontal macrophages to facilitate periodontal regeneration.

Everolimus alleviates CD4+ T cell inflammation by regulating autophagy and cellular redox homeostasis

Aging is associated with the onset and progression of multiple diseases, which limit health span. Chronic low-grade inflammation in the absence of overt infection is considered the simmering source that triggers age-associated diseases. Failure of many cellular processes during aging is mechanistically linked to inflammation; however, the overall decline in the cellular homeostasis mechanism of autophagy has emerged as one of the top and significant inducers of inflammation during aging, frequently known as inflammaging. Thus, physiological or pharmacological interventions aimed at improving autophagy are considered geroprotective. Rapamycin analogs (rapalogs) are known for their ability to inhibit mTOR and thus regulate autophagy. This study assessed the efficacy of everolimus, a rapalog, in regulating inflammatory cytokine production in T cells from older adults. CD4+ T cells from older adults were treated with a physiological dose of everolimus (0.01 µM), and indices of autophagy and inflammation were assessed to gain a mechanistic understanding of the effect of everolimus on inflammation. Everolimus (Ever) upregulated autophagy and broadly alleviated inflammatory cytokines produced by multiple T cell subsets. Everolimus's ability to alleviate the cytokines produced by Th17 subsets of T cells, such as IL-17A and IL-17F, was dependent on autophagy and antioxidant signaling pathways. Repurposing the antineoplastic drug everolimus for curbing inflammaging is promising, given the drug's ability to restore multiple cellular homeostasis mechanisms.

Osteoporosis: interferon-gamma-mediated bone remodeling in osteoimmunology

As the world population ages, osteoporosis, the most common disease of bone metabolism, affects more than 200 million people worldwide. The etiology is an imbalance in bone remodeling process resulting in more significant bone resorption than bone remodeling. With the advent of the osteoimmunology field, the immune system's role in skeletal pathologies is gradually being discovered. The cytokine interferon-gamma (IFN-γ), a member of the interferon family, is an important factor in the etiology and treatment of osteoporosis because it mediates bone remodeling. This review starts with bone remodeling process and includes the cellular and key signaling pathways of bone remodeling. The effects of IFN-γ on osteoblasts, osteoclasts, and bone mass are discussed separately, while the overall effects of IFN-γ on primary and secondary osteoporosis are summarized. The net effect of IFN-γ on bone appears to be highly dependent on the environment, dose, concentration, and stage of cellular differentiation. This review focuses on the mechanisms of bone remodeling and bone immunology, with a comprehensive discussion of the relationship between IFN-γ and osteoporosis. Finding the paradoxical balance of IFN-γ in bone immunology and exploring the potential of its clinical application provide new ideas for the clinical treatment of osteoporosis and drug development.

Global trends in research on aging associated with periodontitis from 2002 to 2023: a bibliometric analysis

Background

Aging has been implicated in many chronic inflammatory diseases, including periodontitis. Periodontitis is an inflammatory disease caused by long-term irritation of the periodontal tissues by the plaque biofilm on the surface of the teeth. However, only a few bibliometric analyses have systematically studied this field to date. This work sought to visualize research hot spots and trends in aging associated with periodontitis from 2002 to 2023 through bibliometric approaches.

Methods

Graphpad prism v8.0.2 was used to analyse and plot annual papers, national publication trends and national publication heat maps. In addition, CtieSpace (6.1.6R (64-bit) Advanced Edition) and VOSviewer (version 1.6.18) were used to analyse these data and visualize the scientific knowledge graph.

Results

The number of documents related to aging associated with periodontitis has steadily increased over 21 years. With six of the top ten institutions in terms of publications coming from the US, the US is a major driver of research in this area. journal of periodontology is the most published journal in the field. Tonetti MS is the most prolific authors and co-cited authors in the field. Journal of Periodontology and Journal of Clinical Periodontology are the most popular journals in the field with the largest literature. Periodontitis, Alzheimer's disease, and peri-implantitis are current hot topics and trends in the field. Inflammation, biomarkers, oxidative stress cytokines are current research hotspots in this field.

Conclusion

Our research found that global publications regarding research on aging associated with periodontitis increased dramatically and were expected to continue increasing. Inflammation and aging, and the relationship between periodontitis and systemic diseases, are topics worthy of attention.

Interleukin-38: A crucial player in periodontitis

BACKGROUND

The objective of this study was to compare the levels of gingival crevicular fluid (GCF), salivary, and serum matrix metalloproteinase-9, interleukin (IL)-17, IL-36γ, and IL-38 in individuals with healthy periodontium, gingivitis, and periodontitis and to evaluate their correlations with clinical periodontal parameters.

MATERIALS AND METHODS

Ninety systemically healthy and nonsmoking volunteers divided into a healthy (H) group (n = 30), a gingivitis (G) group (n = 30), and a periodontitis (P) group (n = 30) were included in this study. Clinical periodontal parameters of volunteers were recorded, and GCF, unstimulated saliva, and serum samples were collected. Data analysis was done with enzyme-linked immunosorbent assays. The Kruskal-Wallis test and Bonferroni correction were used for multiple comparisons and post hoc statistical analyses.

RESULTS

The group H had significantly lower clinical parameters than the group P (p < 0.001). GCF and salivary IL-36γ and IL-38 levels were significantly higher in the group P than in the H and G groups (p < 0.05). Positive correlations between biochemical findings and clinical periodontal parameters were observed.

CONCLUSIONS

IL-36γ and IL-38 levels in GCF, saliva, and serum correlate with clinical periodontal parameters and may play a role in determining the activity of periodontitis.

Role of microbiota-gut-brain axis in natural aging-related alterations in behavior

Introduction

Aging is a complex, time-dependent biological process that involves a decline of overall function. Over the past decade, the field of intestinal microbiota associated with aging has received considerable attention. However, there is limited information surrounding microbiota-gut-brain axis (MGBA) to further reveal the mechanism of aging.

Methods

In this study, locomotory function and sensory function were evaluated through a series of behavioral tests.Metabolic profiling were determined by using indirect calorimetry.16s rRNA sequence and targeted metabolomics analyses were performed to investigate alterations in the gut microbiota and fecal short-chain fatty acids (SCFAs). The serum cytokines were detected by a multiplex cytokine assay.The expression of proinflammatory factors were detected by western blotting.

Results

Decreased locomotor activity, decreased pain sensitivity, and reduced respiratory metabolic profiling were observed in aged mice. High-throughput sequencing revealed that the levels of genus Lactobacillus and Dubosiella were reduced, and the levels of genus Alistipes and Bacteroides were increased in aged mice. Certain bacterial genus were directly associated with the decline of physiological behaviors in aged mice. Furthermore, the amount of fecal SCFAs in aged mice was decreased, accompanied by an upregulation in the circulating pro-inflammatory cytokines and increased expression of inflammatory factors in the brain.

Discussion

Aging-induced microbial dysbiosis was closely related with the overall decline in behavior, which may attribute to the changes in metabolic products, e.g., SCFAs, caused by an alteration in the gut microbiota, leading to inflammaging and contributing to neurological deficits. Investigating the MGBA might provide a novel viewpoint to exploring the pathogenesis of aging and expanding appropriate therapeutic targets.

Dental radiographic changes in individuals with COVID-19: a controlled retrospective study

OBJECTIVE

The aim of this study is to compare the pre-COVID-19 and post-COVID-19 dental radiological findings of individuals with positive rRT-PCR test results and with healthy controls using the apical periodontitis grade scale (APGS), radiographic-based periodontal bone loss (R-PBL), and radiographic DMFT indices, and to investigate the relatively long-term dental effects of COVID-19.

METHODS

This study included people who had two panoramic radiographs taken between 2018 and 2022. There are 52 patients with positive rRT-PCR tests in the study group. The control group included 50 individuals. Study and control groups were compared using the apical periodontitis grade scale (APGS), radiographic-based periodontal bone loss (R-PBL), and radiographic DMFT indices.

RESULTS

Although results showed a significant difference in percentage R-PBL value and R-PBL types in the study group, there was no significant difference in percentage R-PBL value and R-PBL types in the control group. Also, both groups showed a significant difference in the DMFT index.

CONCLUSIONS

According to the results of this study, it can be said that COVID-19 increases the incidence of periodontitis, and it can be interpreted that the pandemic may adversely affect the general oral health of all people.

Interaction between immuno-stem dual lineages in jaw bone formation and injury repair

The jawbone, a unique structure in the human body, undergoes faster remodeling than other bones due to the presence of stem cells and its distinct immune microenvironment. Long-term exposure of jawbones to an oral environment rich in microbes results in a complex immune balance, as shown by the higher proportion of activated macrophage in the jaw. Stem cells derived from the jawbone have a higher propensity to differentiate into osteoblasts than those derived from other bones. The unique immune microenvironment of the jaw also promotes osteogenic differentiation of jaw stem cells. Here, we summarize the various types of stem cells and immune cells involved in jawbone reconstruction. We describe the mechanism relationship between immune cells and stem cells, including through the production of inflammatory bodies, secretion of cytokines, activation of signaling pathways, etc. In addition, we also comb out cellular interaction of immune cells and stem cells within the jaw under jaw development, homeostasis maintenance and pathological conditions. This review aims to eclucidate the uniqueness of jawbone in the context of stem cell within immune microenvironment, hopefully advancing clinical regeneration of the jawbone.

The Genetic Aspects of Periodontitis Pathogenesis and the Regenerative Properties of Stem Cells

Periodontitis (PD) is a prevalent and chronic inflammatory disease with a complex pathogenesis, and it is associated with the presence of specific pathogens, such as Porphyromonas gingivalis. Dysbiosis and dysregulated immune responses ultimately lead to chronic inflammation as well as tooth and alveolar bone loss. Multiple studies have demonstrated that genetic polymorphisms may increase the susceptibility to PD. Furthermore, gene expression is modulated by various epigenetic mechanisms, such as DNA methylation, histone modifications, or the activity of non-coding RNA. These processes can also be induced by PD-associated pathogens. In this review, we try to summarize the genetic processes that are implicated in the pathogenesis of PD. Furthermore, we discuss the use of these mechanisms in diagnosis and therapeutic purposes. Importantly, novel treatment methods that could promote tissue regeneration are greatly needed in PD. In this paper, we also demonstrate current evidence on the potential use of stem cells and extracellular vesicles to stimulate tissue regeneration and suppress inflammation. The understanding of the molecular mechanisms involved in the pathogenesis of PD, as well as the impact of PD-associated bacteria and stem cells in these processes, may enhance future research and ultimately improve long-term treatment outcomes.

Single-cell RNA landscape of osteoimmune microenvironment in osteoporotic vertebral compression fracture and Kümmell's disease

Background: Single-cell RNA sequencing (scRNA-seq) enables specific analysis of cell populations at single-cell resolution; however, there is still a lack of single-cell-level studies to characterize the dynamic and complex interactions between osteoporotic vertebral compression fractures (OVCFs) and Kümmell's disease (KD) in the osteoimmune microenvironment. In this study, we used scRNA-seq analysis to investigate the osteoimmune microenvironment and cellular composition in OVCFs and KD. Methods: ScRNA-seq was used to perform analysis of fractured vertebral bone tissues from one OVCF and one KD patients, and a total of 8,741 single cells were captured for single-cell transcriptomic analysis. The cellularity of human vertebral bone tissue was further analyzed using uniform manifold approximation and projection. Pseudo-time analysis and gene enrichment analysis revealed the biological function of cell fate and its counterparts. CellphoneDB was used to identify the interactions between bone cells and immune cells in the osteoimmune microenvironment of human vertebral bone tissue and their potential functions. Results: A cellular profile of the osteoimmune microenvironment of human vertebral bone tissue was established, including mesenchymal stem cells (MSCs), pericytes, myofibroblasts, fibroblasts, chondrocytes, endothelial cells (ECs), granulocytes, monocytes, T cells, B cells, plasma cells, mast cells, and early erythrocytes. MSCs play an immunoregulatory function and mediate osteogenic differentiation and cell proliferation. The differentiation trajectory of osteoclasts in human vertebral bone tissue was also revealed. In addition, ECs actively participate in inflammatory infiltration and coupling with bone cells. T and B cells actively participate in regulating bone homeostasis. Finally, by identifying the interaction of ligand-receptor pairs, we found that immune cells and osteoclasts have bidirectional regulatory characteristics, have the effects of regulating bone resorption by osteoclasts and promoting bone formation, and are essential for bone homeostasis. It is also highlighted that CD8-TEM cells and osteoclasts might crosstalk via CD160-TNFRSF14 ligand-receptor interaction. Conclusion: Our analysis reveals a differential landscape of molecular pathways, population composition, and cell-cell interactions during OVCF development into KD. OVCFs exhibit a higher osteogenic differentiation capacity, owing to abundant immune cells. Conversely, KD results in greater bone resorption than bone formation due to depletion of MSCs and a relatively suppressed immune system, and this immune imbalance eventually leads to vertebral avascular necrosis. The site of action between immune cells and osteoclasts is expected to be a new therapeutic target, and these results may accelerate mechanistic and functional studies of osteoimmune cell types and specific gene action in vertebral avascular necrosis and pathological bone loss diseases, paving the way for drug discovery.

Cornus officinalis: a potential herb for treatment of osteoporosis

Osteoporosis (OP) is a systemic metabolic skeletal disorder characterized by a decline in bone mass, bone mineral density, and deterioration of bone microstructure. It is prevalent among the elderly, particularly postmenopausal women, and poses a substantial burden to patients and society due to the high incidence of fragility fractures. Kidney-tonifying Traditional Chinese medicine (TCM) has long been utilized for OP prevention and treatment. In contrast to conventional approaches such as hormone replacement therapy, TCM offers distinct advantages such as minimal side effects, low toxicity, excellent tolerability, and suitability for long-term administration. Extensive experimental evidence supports the efficacy of kidney-tonifying TCM, exemplified by formulations based on the renowned herb Cornus officinalis and its bioactive constituents, including morroniside, sweroside, flavonol kaempferol, Cornuside I, in OP treatment. In this review, we provide a comprehensive elucidation of the underlying pathological principles governing OP, with particular emphasis on bone marrow mesenchymal stem cells, the homeostasis of osteogenic and osteoclastic, and the regulation of vascular and immune systems, all of which critically influence bone homeostasis. Furthermore, the therapeutic mechanisms of Cornus officinalis-based TCM formulations and Cornus officinalis-derived active constituents are discussed. In conclusion, this review aims to enhance understanding of the pharmacological mechanisms responsible for the anti-OP effects of kidney-tonifying TCM, specifically focusing on Cornus officinalis, and seeks to explore more efficacious and safer treatment strategies for OP.

IFNγ Transcribed by IRF1 in CD4+ Effector Memory T Cells Promotes Senescence-Associated Pulmonary Fibrosis

Physiologically aged lungs are prone to senescence-associated pulmonary diseases (SAPD). This study aimed to determine the mechanism and subtype of aged T cells affecting alveolar type II epithelial (AT2) cells, which promote the pathogenesis of senescence-associated pulmonary fibrosis (SAPF). Cell proportions, the relationship between SAPD and T cells, and the aging- and senescence-associated secretory phenotype (SASP) of T cells between young and aged mice were analyzed using lung single-cell transcriptomics. SAPD was monitored by markers of AT2 cells and found to be induced by T cells. Furthermore, IFNγ signaling pathways were activated and cell senescence, SASP, and T cell activation were shown in aged lungs. Physiological aging led to pulmonary dysfunction and TGF-β1/IL-11/MEK/ERK (TIME) signaling-mediated SAPF, which was induced by senescence and SASP of aged T cells. Especially, IFNγ was produced by the accumulated CD4+ effector memory T (TEM) cells in the aged lung. This study also found that physiological aging increased pulmonary CD4+ TEM cells, IFNγ was produced mainly by CD4+ TEM cells, and pulmonary cells had increased responsiveness to IFNγ signaling. Specific regulon activity was increased in T cell subclusters. IFNγ transcriptionally regulated by IRF1 in CD4+ TEM cells promoted the epithelial-to-mesenchymal transition by activating TIME signaling and cell senescence of AT2 cells with aging. Accumulated IRF1+CD4+ TEM produced IFNγ in lung with aging and anti-IRF1 primary antibody treatment inhibited the expression of IFNγ. Aging might drive T cell differentiation toward helper T cells with developmental trajectories and enhance cell interactions of pulmonary T cells with other surrounding cells. Thus, IFNγ transcribed by IRF1 in CD4+ effector memory T cells promotes SAPF. IFNγ produced by CD4+ TEM cells in physiologically aged lungs could be a therapeutic target for preventing SAPF.

Osteoclasts in Osteosarcoma: Mechanisms, Interactions, and Therapeutic Prospects

Osteosarcoma is an extremely malignant tumor, and its pathogenesis is complex and remains incompletely understood. Most cases of osteosarcoma are accompanied by symptoms of bone loss or result in pathological fractures due to weakened bones. Enhancing the survival rate of osteosarcoma patients has proven to be a long-standing challenge. Numerous studies mentioned in this paper, including in-vitro, in-vivo, and in-situ studies have consistently indicated a close association between the symptoms of bone loss associated with osteosarcoma and the presence of osteoclasts. As the sole cells capable of bone resorption, osteoclasts participate in a malignant cycle within the osteosarcoma microenvironment. These cells interact with osteoblasts and osteosarcoma cells, secreting various factors that further influence these cells, disrupting bone homeostasis, and shifting the balance toward bone resorption, thereby promoting the onset and progression of osteosarcoma. Moreover, the interaction between osteoclasts and various other cells types, such as tumor-associated macrophages, myeloid-derived suppressor cells, DCs cells, T cells, and tumor-associated fibroblasts in the osteosarcoma microenvironment plays a crucial role in disease progression. Consequently, understanding the role of osteoclasts in osteosarcoma has sparked significant interest. This review primarily examines the physiological characteristics and functional mechanisms of osteoclasts in osteosarcoma, and briefly discusses potential therapies targeting osteoclasts for osteosarcoma treatment. These studies provide fresh ideas and directions for future research on the treatment of osteosarcoma.

Effect of Hyperbaric Oxygen and Inflammation on Human Gingival Mesenchymal Stem/Progenitor Cells

The present study explores for the first time the effect of hyperbaric oxygen (HBO) on gingival mesenchymal stem cells' (G-MSCs) gene expression profile, intracellular pathway activation, pluripotency, and differentiation potential under an experimental inflammatory setup. G-MSCs were isolated from five healthy individuals (n = 5) and characterized. Single (24 h) or double (72 h) HBO stimulation (100% O2, 3 bar, 90 min) was performed under experimental inflammatory [IL-1β (1 ng/mL)/TNF-α (10 ng/mL)/IFN-γ (100 ng/mL)] and non-inflammatory micro-environment. Next Generation Sequencing and KEGG pathway enrichment analysis, G-MSCs' pluripotency gene expression, Wnt-/β-catenin pathway activation, proliferation, colony formation, and differentiation were investigated. G-MSCs demonstrated all mesenchymal stem/progenitor cells' characteristics. The beneficial effect of a single HBO stimulation was evident, with anti-inflammatory effects and induction of differentiation (TLL1, ID3, BHLHE40), proliferation/cell survival (BMF, ID3, TXNIP, PDK4, ABL2), migration (ABL2) and osteogenic differentiation (p < 0.05). A second HBO stimulation at 72 h had a detrimental effect, significantly increasing the inflammation-induced cellular stress and ROS accumulation through HMOX1, BHLHE40, and ARL4C amplification and pathway enrichment (p < 0.05). Results outline a positive short-term single HBO anti-inflammatory, regenerative, and differentiation stimulatory effect on G-MSCs. A second (72 h) stimulation is detrimental to the same properties. The current results could open new perspectives in the clinical application of short-termed HBO induction in G-MSCs-mediated periodontal reparative/regenerative mechanisms.

Impact of an Okinawa/Nordic based diet on endocrinological and periodontal conditions in individuals with type 2 diabetes. A randomized case-control study

OBJECTIVES

To assess if the results following intake of a diet using an Okinawan-based Nordic diet (OBND) over one month differs in endocrinological, periodontal clinical outcome, and serum cytokine levels compared to a standard hospital care diet in individuals with diabetes type 2 (T2D) (control group).

BACKGROUND

Scientific evidence suggests that the use of diet for individuals with T2D may be beneficial.

METHODS

Participating individuals with T2D were randomly assigned to a test (OBND) (n = 14), or control group (n = 16). Anthropometric data, blood glucose levels, HbA1c levels, lipids, serum inflammation markers (CRP, and a routine panel of 24 cytokines), blood pressure, gingival bleeding on probing (BOP), probing pocket depths (PPD), and clinical attachment levels (CAL) were studied.

RESULTS

Statistical analyses of baseline study data failed to demonstrate study group differences. The mean weight reduction was greater in the OBND group (4.1 kg) versus the control group (1.3 kg) (p < 0.01). The reduction in BMI was 1.4 kg/m2 in OBND (p < 0.001) and 0.5 kg/m2 in the control group, respectively (p < 0.01). Diastolic and systolic blood pressure reductions were greater in the OBND group than in the control group (p < 0.01). Periodontal study parameters (BOP % scores) and (PPD values) decreased (p < 0.001) overall with no between group differences. The OBND resulted in reduction of serum levels of IFNγ, Eotaxin IL-9, IP10,IL17a, MCP-1,m and PDFBB compared to the control diet.

CONCLUSIONS

A strict T2D- diet provides an association between reduction in serum HbA1c and BOP scores. Serum levels decreases in IFNγ, Eotaxin IL-9, IP-10, IL17a. MCP-1, and PDFBB were only found in the test group.

The Presence of Periodontitis Exacerbates Non-Alcoholic Fatty Liver Disease via Sphingolipid Metabolism-Associated Insulin Resistance and Hepatic Inflammation in Mice with Metabolic Syndrome

Clinical studies have shown that periodontitis is associated with non-alcoholic fatty liver disease (NAFLD). However, it remains unclear if periodontitis contributes to the progression of NAFLD. In this study, we generated a mouse model with high-fat diet (HFD)-induced metabolic syndrome (MetS) and NAFLD and oral P. gingivalis inoculation-induced periodontitis. Results showed that the presence of periodontitis increased insulin resistance and hepatic inflammation and exacerbated the progression of NAFLD. To determine the role of sphingolipid metabolism in the association between NAFLD and periodontitis, we also treated mice with imipramine, an inhibitor of acid sphingomyelinase (ASMase), and demonstrated that imipramine treatment significantly alleviated insulin resistance and hepatic inflammation, and improved NAFLD. Studies performed in vitro showed that lipopolysaccharide (LPS) and palmitic acid (PA), a major saturated fatty acid associated with MetS and NAFLD, synergistically increased the production of ceramide, a bioactive sphingolipid involved in NAFLD progression in macrophages but imipramine effectively reversed the ceramide production stimulated by LPS and PA. Taken together, this study showed for the first time that the presence of periodontitis contributed to the progression of NAFLD, likely due to alterations in sphingolipid metabolism that led to exacerbated insulin resistance and hepatic inflammation. This study also showed that targeting ASMase with imipramine improves NAFLD by reducing insulin resistance and hepatic inflammation.

CYP27A1 deficiency promoted osteoclast differentiation

Background

The elevating osteoclast differentiation can lead to an imbalance in bone homeostasis, which was responsible for bone loss and bone diseases, such as osteoporosis. Multiple pathways and molecules have been involved in osteoclast formation, but the role of CYP27A1 in osteoclast differentiation has never been explored.

Methods

CYP27A1 deficient mice were constructed using CRISPR-Cas9 system. Osteoclast differentiation was detected by TRAP staining. Differentially expressed genes (DEGs) were identified using RNA-seq analysis and were confirmed by qRT-PCR and Western blot.

Results

The results showed that CYP27A1 knockout (KO) promoted osteoclast differentiation and bone loss. The transcriptomic analysis revealed that CYP27A1 KO led to differential expression of multiple genes, including ELANE, LY6C2, S100A9, GM20708, BGN, SPARC, and COL1A2, which were confirmed by qRT-PCR and Western blot. Enrichment analysis indicated that these differential genes were significantly associated with osteogenesis-related pathways, such as PPAR signaling, IL-17 signaling, and PI3K/AKT signaling, which were confirmed by qRT-PCR and Western blot.

Conclusions

These results suggested that CYP27A1 was involved in osteoclast differentiation, providing a novel therapeutic target for osteoclast-related diseases.

Identification and validation of a classifier based on hub aging-related genes and aging subtypes correlation with immune microenvironment for periodontitis

BACKGROUND

Periodontitis (PD), an age-related disease, is characterized by inflammatory periodontal tissue loss, and with the general aging of the global population, the burden of PD is becoming a major health concern. Nevertheless, the mechanism underlying this phenomenon remains indistinct. We aimed to develop a classification model for PD and explore the relationship between aging subtypes and the immune microenvironment for PD based on bioinformatics analysis.

MATERIALS AND METHODS

The PD-related datasets were acquired from the Gene Expression Omnibus (GEO) database, and aging-related genes (ARGs) were obtained from the Human Aging Genomic Resources (HAGR). Four machine learning algorithms were applied to screen out the hub ARGs. Then, an artificial neural network (ANN) model was constructed and the accuracy of the model was validated by receiver operating characteristic (ROC) curve analysis. The clinical effect of the model was evaluated by decision curve analysis (DCA). Consensus clustering was employed to determine the aging expression subtypes. A series of bioinformatics analyses were performed to explore the PD immune microenvironment and its subtypes. The hub aging-related modules were defined using weighted correlation network analysis (WGCNA).

RESULTS

Twenty-seven differentially expressed ARGs were dysregulated and a classifier based on four hub ARGs (BLM, FOS, IGFBP3, and PDGFRB) was constructed to diagnose PD with excellent accuracy. Subsequently, the mRNA levels of the hub ARGs were validated by quantitative real-time PCR (qRT-PCR). Based on differentially expressed ARGs, two aging-related subtypes were identified. Distinct biological functions and immune characteristics including infiltrating immunocytes, immunological reaction gene sets, the human leukocyte antigen (HLA) gene, and immune checkpoints were revealed between the subtypes. Additionally, the black module correlated with subtype-1 was manifested as the hub aging-related module and its latent functions were identified.

CONCLUSION

Our findings highlight the critical implications of aging-related genes in modulating the immune microenvironment. Four hub ARGs (BLM, FOS, IGFBP3, and PDGFRB) formed a classification model, and accompanied findings revealed the essential role of aging in the immune microenvironment for PD, providing fresh inspiration for PD etiopathogenesis and potential immunotherapy.

Patients with periodontitis are at a higher risk of stroke: A Taiwanese cohort study

BACKGROUND

This study aimed to investigate the risk of stroke incidence in patients with periodontitis.

METHODS

Data on patients diagnosed with periodontitis were collected from Taiwan's National Health Insurance Research Database and were matched (1:1) with patients without periodontitis between 2001 and 2010. A multivariable Cox survival model was used to predict stroke between patients with and without periodontitis, and the possibility of confounders. Hazard ratios (HRs) with 95% confidence intervals (CIs) were used to explore the risk of stroke in the case and control groups. Diseases found during the follow-up period were analyzed to determine possible effects on the study. A total of 282 560 periodontitis and nonperiodontitis patients were enrolled, with most subjects aged 40 to 59 years.

RESULTS

The overall cumulative incidence of stroke was 2.14 times higher in periodontitis than in nonperiodontitis, and the highest HR was in the more than 80 years age group (HR = 9.30; 95% CI, 7.06-12.26). The multivariate Cox model indicated that the adjusted HR (aHR) between the case and control was 2.03 (95% CI, 1.99-2.08), and a higher aHR was associated with hypertension. Atherosclerosis, atrial fibrillation, obesity, kidney disease, anxiety, and gout discovered during follow-up also showed a potential risk of stroke in patients with periodontitis.

CONCLUSION

Therefore, this study suggests a high risk of stroke in patients with periodontitis.

Wheel-Running Exercise Protects Ovariectomized Mice from Bone Loss via IFN-γ-Mediated Suppression of the NF-κB and MAPK Pathways

Physical exercise is recommended as a preventative approach for osteoporosis; however, the effect of physical exercise on bone mass remains controversial. Additionally, the immune regulation of physical exercise on bone mass remains unclear. To determine whether wheel-running (WR) exercise contributes to improving bone mineral density (BMD) and investigate the involved immune mechanism, ovariectomized (OVX) and sham-operated mice were treated with 8 weeks of WR exercise. The distal femurs of the mice were sequentially scanned, reconstructed, and analyzed using microcomputed tomography and related software to assess BMD and bone microarchitecture. Flow cytometry assays were applied to investigate alterations in immune cells and inflammatory cytokines. In vitro, osteoclast differentiation was conducted to determine the effect of IFN-γ on osteoclastogenesis and the underlying mechanism. As a result, trabecular parameters were decreased in the OVX mice compared with the sham group. However, WR exercise significantly improved the deterioration in the bone microarchitecture of the OVX mice with an increase of 60.00% in BMD, 55.18% in bone volume, 66.67% in trabecular number, 32.52% in trabecular thickness, and a decrease of 19.44% in trabecular separation. Similarly, WR exercise increased the proportion of CD8⁺ T cells from 7.26 ± 1.71% to 10.23 ± 1.35% in the spleen and from 1.62 ± 0.54% to 2.38 ± 0.43% in the bone marrow of the OVX mice (P < 0.05). The expression of IFN-γ was also increased in the OVX + WR mice compared with the OVX mice (1.65 ± 0.45% vs. 2.26 ± 0.34%, P < 0.05). In vitro studies demonstrated an inhibitory effect of IFN-γ on osteoclastogenesis in a dose- and time-dependent manner. Meanwhile, the classical NF-κB and MAPK pathways were found to be critical in IFN-γ-mediated inhibition of osteoclast differentiation. In conclusion, our study discovered that WR exercise rescued bone loss in the OVX mice in an IFN-γ-mediated immunomodulatory manner. After WR exercise, IFN-γ expression was restored by activated CD8⁺ T cells, consequently leading to the inhibition of osteoclastogenesis and the recovery from bone loss through the NF-κB and MAPK pathways.

mTOR Signaling in the Regulation of CD4+ T Cell Subsets in Periodontal Diseases

Periodontal disease results from the inflammatory infiltration by the microbial community which is marked through tooth mobility and alveolar bone resorption. The inflammation in periodontal disease is mediated by CD4⁺ T cells through cytokine secretion and osteoclastogenetic activity. Historically, the inflammatory model in periodontal disease is described through disruption of the balance between two subsets of T helper cells which are T-helper type 1 (Th1) and T-helper type 2 (Th2). However, more and more studies have found that apart from subsets of helper T cells, regulatory T-cells and Th17 cells are also involved in the pathogenesis of periodontal diseases. Growing evidence proves that helper T cells differentiation, activation, and subset determination are under the strong impact of mTOR signaling. mTOR signaling could promote Th1 and Th17 cell differentiation and inhibit Treg commitment through different mTOR complexes, therefore we anticipate a regulation effect of mTOR signaling on periodontal diseases by regulating CD4⁺ T cell subsets. This review aims to integrate the topical researches about the role of different types of Th cells in the pathogenesis of periodontal diseases, as well as the regulation of mTOR signaling in the specification and selection of Th cell commitment.

Molecular Basis of Accelerated Aging with Immune Dysfunction-Mediated Inflammation (Inflamm-Aging) in Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is a chronic connective tissue disorder characterized by immune dysregulation, chronic inflammation, vascular endothelial cell dysfunction, and progressive tissue fibrosis of the skin and internal organs. Moreover, increased cancer incidence and accelerated aging are also found. The increased cancer incidence is believed to be a result of chromosome instability. Accelerated cellular senescence has been confirmed by the shortening of telomere length due to increased DNA breakage, abnormal DNA repair response, and telomerase deficiency mediated by enhanced oxidative/nitrative stresses. The immune dysfunctions of SSc patients are manifested by excessive production of proinflammatory cytokines IL-1, IL-6, IL-17, IFN-α, and TNF-α, which can elicit potent tissue inflammation followed by tissue fibrosis. Furthermore, a number of autoantibodies including anti-topoisomerase 1 (anti-TOPO-1), anti-centromere (ACA or anti-CENP-B), anti-RNA polymerase enzyme (anti-RNAP III), anti-ribonuclear proteins (anti-U1, U2, and U11/U12 RNP), anti-nucleolar antigens (anti-Th/T0, anti-NOR90, anti-Ku, anti-RuvBL1/2, and anti-PM/Scl), and anti-telomere-associated proteins were also found. Based on these data, inflamm-aging caused by immune dysfunction-mediated inflammation exists in patients with SSc. Hence, increased cellular senescence is elicited by the interactions among excessive oxidative stress, pro-inflammatory cytokines, and autoantibodies. In the present review, we will discuss in detail the molecular basis of chromosome instability, increased oxidative stress, and functional adaptation by deranged immunome, which are related to inflamm-aging in patients with SSc.