Autophagy and its significance in periodontal disease

A Novel Therapeutic Calcium Peroxide Loaded Injectable Bio-adhesive Hydrogel Against Periodontitis

OBJECTIVES

Periodontitis is a prevalent oral disease that can significantly impact patients' life quality and systemic health. However, non-surgical subgingival scaling is largely compromised due to poor patient compliance, leading to a high recurrence rate of periodontitis. Therefore, this research aims to explore new approaches to enhance the effectiveness of existing local drug administration therapies.

MATERIALS AND METHODS

Gelatin-oxidized dextran hydrogel loaded with calcium peroxide and penicillin (CP-P hydrogel) was synthesized and characterized using Universal mechanical testing machine, Fourier transform infrared spectroscopy, swelling test, and dissolved oxygen meter. Furthermore, the cytotoxicity, osteogenic ability, antibacterial behavior, and alveolar bone regenerating capability of CP-P hydrogel were conducted both in vitro and in vivo.

RESULTS

The CP-P hydrogel demonstrated excellent mechanical properties, minimal swelling, and ideal biocompatibility. It created more favorable environments in the periodontal pocket by reversing anaerobic environment, eliminating drug-resistant bacteria and enhancing the therapeutic potency of drugs. By continuously releasing drugs in the periodontal pocket, the CP-P hydrogel effectively inhibited bacteria and reduce local inflammation response. In addition to bacteriostatic effects, the CP-P hydrogel also promoted the expression of osteogenic genes and enhanced osteogenic differentiation of PDLSCs in vitro.

CONCLUSIONS

CP-P hydrogel can be developed as a new therapeutic platform to enhance the effectiveness of local drug administration strategy against periodontitis.

The Role of Macrophage Death in Periodontitis: A Review

Periodontitis, an infectious inflammatory disease influenced by various factors, disrupts the delicate balance between the host microbiota and immunity. The resulting excessive immune response exacerbates the progressive destruction of the supporting periodontal tissue. Macrophages are essential elements of the host innate immune system. They are pivotal components in the periodontal immune microenvironment and actively participate in both physiological and pathological processes of periodontal tissue. When confronted with periodontitis-related irritant factors, macrophages may differentiate to pro- or anti-inflammatory subtypes that affect tissue homeostasis. Additionally, macrophages may die in response to bacterial infections, potentially affecting the severity of periodontitis. This article reviews the typical mechanisms underlying macrophage death and its effects on periodontitis. We describe five forms of macrophage death in periodontitis: apoptosis, pyroptosis, necroptosis, ferroptosis, and ETosis. Our review of macrophage death in the pathophysiology of periodontitis enhances comprehension of the pathogenesis of periodontitis that will be useful for clinical practice. Although our review elucidates the complex mechanisms by which macrophage death and inflammatory pathways perpetuate periodontitis, unresolved issues remain, necessitating further research.

Expression dynamics of microRNA-223/Ras-associated binding protein 12 axis in Stage III/Grade B periodontal disease: A case-control analysis

Background

The intricate interplay between periodontal polymicrobial flora and an altered immune response is the central cause of periodontal disease. Multiple cell death methods and their interactions, along with the associated signaling pathways, significantly impact the initiation and advancement of periodontitis. Our speculation revolves around the role of the miR-223/Ras-associated binding protein (RAB12) signaling axis in regulating autophagy-induced pyroptosis, contributing to the pathophysiology of periodontitis. Thus, this study aimed to investigate miR-223 and RAB12 expression patterns in Stage III/Grade B periodontal disease.

Materials and Methods

The study included 50 healthy individuals and 50 patients diagnosed with Stage III/Grade B periodontal disease. Clinical parameters were cataloged for each participant. miRNA-223 underwent an in silico analysis to identify its potential target genes. Gingival crevicular fluid (GCF) samples were collected from the subjects for real-time polymerase chain reaction to evaluate the expression of both miR-223 and the RAB12 gene.

Results

The miRTargetLink2.0 analysis highlighted the RAB12 gene as a prime target for miR-223. In periodontal disease patients, miR-223 and RAB12 gene expressions significantly increased (15.21 and 34.70-fold changes, respectively; P < 0.05). Receiver operating characteristic analysis suggested that miR-223 is a potential biomarker for periodontal disease, with 76% diagnostic accuracy and an area under the curve of 0.777 (P < 0.01).

Conclusion

MicroRNA-223 and its target gene RAB12 exhibit high expression levels in GCF samples from individuals with periodontal disease. This suggests modulation of autophagy and the signaling mechanism for pyroptotic cell death in periodontal tissues during pathogenesis. Consequently, the miR-223/RAB12 axis might represent a plausible link for periodontal disease.

Proanthocyanidin enhances the endogenous regeneration of alveolar bone by elevating the autophagy of PDLSCs

OBJECTIVE

This study aimed to investigate the effect of proanthocyanidin (PA) on osteogenesis mediated by periodontal ligament stem cells (PDLSCs) and endogenous alveolar bone regeneration.

BACKGROUND

Leveraging the osteogenic potential of resident stem cells is a promising strategy for alveolar bone regeneration. PA has been reported to be effective in osteogenesis. However, the effect and mechanism of PA on the osteogenic differentiation of PDLSCs remain elusive.

METHODS

Human PDLSCs were treated with various doses of PA to assess the cell proliferation using Cell Counting Kit-8. The osteogenic differentiation ability was detected by qRT-PCR analysis, western blot analysis, Alizarin red S staining, and Alkaline Phosphatase staining. The level of autophagy was evaluated by confocal laser scanning microscopy, transmission electron microscopy, and western blot analysis. RNA sequencing was utilized to screen the potential signaling pathway. The alveolar bone defect model of rats was created to observe endogenous bone regeneration.

RESULTS

PA activated intracellular autophagy in PDLSCs, resulting in enhanced osteogenic differentiation. Moreover, this effect could be abolished by the autophagy inhibitor 3-Methyladenine. Mechanistically, the PI3K/Akt/mTOR pathway was negatively correlated with PA-mediated autophagy activation. Lastly, PA promoted the alveolar bone regeneration in vivo, and this effect was reversed when the autophagy process was blocked.

CONCLUSION

PA may activate autophagy by inhibiting PI3K/Akt/mTOR signaling pathway to promote the osteogenesis of PDLSCs and enhance endogenous alveolar bone regeneration.

CKIP-1 Promotes P. gingivalis-Induced Inflammation of Periodontal Soft Tissues by Inhibiting Autophagy

As a chronic inflammatory disease, periodontitis involves many biological processes including autophagy. At the same time, casein kinase 2 interacting protein-1 (CKIP-1) was reported to play a role in regulation of inflammation. But whether CKIP-1 and autophagy interact in periodontitis remains unclear. In this paper, our research team verified the levels of CKIP-1 expression and autophagy increase in the periodontal tissues of a ligature-induced periodontitis mouse model. And this result was also confirmed in Porphyromonas gingivalis (Pg)-induced human gingival fibroblasts (HGF) and human periodontal ligament cells (PDLC). We also showed the autophagy level in periodontal tissues is higher in Ckip-1 knockout (KO) mice than wild type (WT). At the same time, CKIP-1 knockdown lentivirus was used in PDLC and HGF, and it was found that silencing CKIP-1 significantly activated autophagy. Unfortunately, the regulatory role of autophagy in periodontitis is still unclear. Then, the autophagy agonist Rapamycin and inhibitor 3-MA were used in a periodontitis mouse model to investigate periodontal tissue destruction. We found the inflammation in periodontal tissue was reduced when autophagy activated. All these conclusions have been verified both in vivo and in vitro experiments. Finally, our research proved that silencing CKIP-1 reduces the expression of inflammatory cytokines in Pg-induced PDLC and HGF by regulating autophagy. Overall, a new role for CKIP-1 in regulating periodontal tissue inflammation was demonstrated in our study, and it is possible to treat periodontitis by targeting the CKIP-1 gene.

Aging Aggravates Periodontal Inflammatory Responses and Alveolar Bone Resorption by Porphyromonas gingivalis Infection

Periodontitis is a chronic inflammatory disease driven by periodontal pathogens such as Porphyromonas gingivalis (P. gingivalis), and its prevalence increases with age. However, little is known about the effect of immunosenescence on inflammatory response to P. gingivalis infection. In the present study, 16S rDNA sequencing analysis showed the relative abundance of P. gingivalis was significantly higher in periodontitis patients than healthy group, but there was no difference between the young (20 to 40 years old) and old (65 to 86 years old) periodontitis groups. Furthermore, the cytotoxic effect of P. gingivalis was greater on old THP-1 macrophages and on bone mar-row-derived cells (BMDMs) from old mice, and levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-12 were higher in old than in young THP-1 macrophages. Furthermore, the activations of inflammasome components for IL-1β production by P. gingivalis infection were greater in old THP-1 macrophages. Finally, bone loss was significantly greater in P. gingivalis-infected aged mice than in young mice. These findings indicate that aging aggravates P. gingivalis-induced inflammatory cytokine secretion and inflammasome activation. The study enhances understanding of the relationship between periodontal immunosenescence and inflammatory response in the elderly.

Zingerone-Induced Autophagy Suppresses IL-1β Production by Increasing the Intracellular Killing of Aggregatibacter actinomycetemcomitans in THP-1 Macrophages

Periodontitis is caused by the inflammation of tooth-supporting tissue by pathogens such as Aggregatibacter actinomycetemcomitans. Interleukin-1β (IL-1β), a pro-inflammatory cytokine, triggers a series of inflammatory reactions and promotes bone resorption. The aim of this study was to examine the molecular mechanism and anti-inflammatory function of zingerone, a dietary phenolic found in Zingiber officinale, on periodontal inflammation induced by A. actinomycetemcomitans. Zingerone attenuated A. actinomycetemcomitans-induced nitric oxide (NO) production by inhibiting the expression of inducible nitric oxide synthase (iNOS) in THP-1 macrophages. Zingerone also inhibited the expression of tumor necrosis factor (TNF)-α, IL-1β, and their signal pathway molecules including the toll-like receptor (TLR)/mitogen-activated protein kinase (MAPKase). In particular, zingerone suppressed the expression of absent in melanoma 2 (AIM2) inflammasome components on IL-1β production. Moreover, zingerone enhanced autophagosome formation and the expressions of autophagy-associated molecules. Interestingly, zingerone reduced the intracellular survival of A. actinomycetemcomitans. This was blocked by an autophagy inhibitor, which reversed the decrease in IL-1β production by zingerone. Finally, zingerone alleviated alveolar bone absorption in an A. actnomycetemcomitans-induced periodontitis mice model. Our data suggested that zingerone has potential use as a treatment for periodontal inflammation induced by A. actinomycetemcomitans.

Macrophages induce gingival destruction via Piezo1-mediated MMPs-degrading collagens in periodontitis

Macrophages are an integral part of the innate immune response in periodontal tissue and play a crucial role in the progression of periodontitis. Here we reported that macrophages also provoke periodontitis-induced gingival destruction through Piezol-mediated collagen degradation. We discovered that the PIEZO1 expression was markedly elevated in patients with periodontitis through transcriptomic profiling. Moreover, Piezo1 promoted macrophage polarization toward the M1 type in response to lipopolysaccharide (LPS) and induced production of proinflammatory cytokines, which in turn stimulated production of matrix metalloproteinases (MMPs) leading to collagen degradation. Our study suggests that Piezol might be a potential therapeutic target for treating periodontitis-induced gingival destruction.

Low concentrations of tumor necrosis factor-alpha promote human periodontal ligament stem cells osteogenic differentiation by activation of autophagy via inhibition of AKT/mTOR pathway

BACKGROUND

Tumor necrosis factor-alpha (TNF-α) is one of the crucial inflammatory factors in alveolar bone metabolism during the process of periodontitis. Autophagy is indispensable for proper osteoblast function. However, the effects of autophagy on osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) in inflammatory microenvironment and the underlying mechanisms remain to be clarified. The aim of the present study was to investigate whether autophagy participates in hPDLSCs differentiation after treated with TNF-α and explore the underlying mechanisms.

METHODS AND RESULTS

Characterizations of hPDLSCs were evaluated by Alizarin-red S staining, Oil red staining and flow cytometry. hPDLSCs were treated with various concentrations of TNF-α. Rapamycin or 3MA was used to achieve or inhibit autophagy activation. AKT signaling was inhibited using ARQ092. Cell proliferation was evaluated using Cell Counting Kit-8 (CCK8) assay. Real-time reverse transcriptase-polymerase chain reaction assay (RT-PCR), western blot, alkaline phosphatase (ALP) staining and Alizarin Red S staining were applied to evaluate levels of osteogenic differentiation and autophagy. CCK8 showed that low concentrations of TNF-α had no influence on cell proliferation, while high concentrations of TNF-α inhibited proliferation. Low concentrations of TNF-α promoted osteogenic differentiation and autophagy, while high concentrations of TNF-α inhibited osteogenic differentiation and autophagy in hPDLSCs. The levels of osteogenic differentiation in hPDLSCs were partly effected after co-incubation with 0.1 ng/mL TNF-α with 3MA or Rapamycin. ARQ092 enhanced 0.1 ng/mL TNF-α-induced ALP expression and mineral nodule formation.

CONCLUSION

Low concentrations of TNF-α promote hPDLSCs osteogenic differentiation by activation of autophagy via inhibition of AKT/mTOR signaling.

Autophagy as a potential mechanism underlying the biological effect of 1,25-Dihydroxyvitamin D3 on periodontitis: a narrative review

The major active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25D3), is known for its wide bioactivity in periodontal tissues. Although the exact mechanisms underlying its protective action against periodontitis remain unclear, recent studies have shown that 1,25D3 regulates autophagy. Autophagy is vital for intracellular pathogen invasion control, inflammation regulation, and bone metabolic balance in periodontal tissue homeostasis, and its regulation could be an interesting pathway for future periodontal studies. Since vitamin D deficiency is a worldwide health problem, its role as a potential regulator of autophagy provides new insights into periodontal diseases. Based on this premise, this narrative literature review aimed to investigate the possible connection between 1,25D3 and autophagy in periodontitis. A comprehensive literature search was conducted on PubMed using the following keywords (e.g., vitamin D, autophagy, periodontitis, pathogens, epithelial cells, immunity, inflammation, and bone loss). In this review, the latest studies on the protective action of 1,25D3 against periodontitis and the regulation of autophagy by 1,25D3 are summarized, and the potential role of 1,25D3-activated autophagy in the pathogenesis of periodontitis is analyzed. 1,25D3 can exert a protective effect against periodontitis through different signaling pathways in the pathogenesis of periodontitis, and at least part of this regulatory effect is achieved through the activation of the autophagic response. This review will help clarify the relationship between 1,25D3 and autophagy in the homeostasis of periodontal tissues and provide perspectives for researchers to optimize prevention and treatment strategies in the future.

Impaired autophagy flux by lncRNA NEAT1 is critical for inflammation factors production in human periodontal ligament stem cells with nicotine treatment

BACKGROUND AND OBJECTIVES

Periodontitis is the top reason for tooth loss, and smoking significantly increases severe periodontitis risk. Defective autophagy has been reported to play a vital role in periodontitis. This study aimed to elucidate the relationship between autophagy and inflammation factors production in nicotine-treated periodontal ligament stem cells (PDLSCs) and the underlying mechanism.

METHODS

In this study, transmission electron microscopy, immunofluorescence, and the mCherry-GFP-LC3 plasmid were used to study autophagy flux. The gene levels of inflammation factors and long noncoding RNA nuclear paraspeckle assembly transcript 1 (lncRNA NEAT1) were detected by quantitative real-time PCR (qRT-PCR). Western blot was performed to assess the protein levels of autophagic markers and α7 nicotinic acetylcholine receptor (α7nAChR).

RESULTS

We found that nicotine impaired autophagosome-lysosome fusion and lysosome functions to block autophagy flux, contributing to inflammatory factors production in nicotine-treated PDLSCs. Moreover, nicotine upregulated NEAT1 by activating α7nAChR. NEAT1 decreased autophagy flux by downregulating syntaxin 17 (STX17).

CONCLUSION

Our data indicate that NEAT1-decreased autophagy flux is pivotal for inflammation factors production in nicotine-treated PDLSCs.

Genome- and Transcriptome-Wide Association Studies Identify Susceptibility Genes and Pathways for Periodontitis

Several genes associated with periodontitis have been identified through genome-wide association studies (GWAS); however, known genes only explain a minority of the estimated heritability. We aimed to explore more susceptibility genes and the underlying mechanisms of periodontitis. Firstly, a genome-wide meta-analysis of 38,532 patients and 316,185 healthy controls was performed. Then, cross- and single-tissue transcriptome-wide association studies (TWAS) were conducted based on GWAS summary statistics and the Genotype-Tissue Expression (GTEx) project. Risk genes were evaluated to determine if they were differentially expressed in periodontitis sites compared with unaffected sites using public datasets. Finally, gene co-expression network analysis was conducted to identify the functional biology of the susceptible genes. A total of eight single nucleotide polymorphisms (SNPs) within the introns of lncRNA LINC02141 approached genome-wide significance after meta-analysis. EZH1 was identified as a novel susceptibility gene for periodontitis by TWAS and was significantly upregulated in periodontitis-affected gingival tissues. EZH1 co-expression genes were greatly enriched in the cell-substrate junction, focal adhesion and other important pathways. Our findings may offer a fundamental clue for comprehending the genetic mechanisms of periodontitis.

Argpyrimidine bonded to RAGE regulates autophagy and cell cycle to cause periodontal destruction

Argpyrimidine (APMD), a methylglyoxal-arginine-derived product, is one of the main products of diabetes mellitus. We aimed to systematically investigate the role of APMD in regulating autophagy activity, with a specific focus on the finding of APDM binding molecule, matching amino acid residues, autophagy flux and proteins, cell cycle arrest, cell skeleton and migration, PI3K/AKT/mTOR pathways, inflammatory signals, alveolar bone destruction, and inhibition verification. In this study, binding to 59/94/121 amino acid residues of advanced glycosylation end product receptor (RAGE), APMD suppressed PI3K/AKT/mTOR pathway to attenuate cell survival of periodontal ligament cells (PDLCs). Simultaneously, autophagy proteins ATG5, Beclin1, and LC3-II/I expression ratio were upregulated while P62/SQSTM was downregulated. Cell cycle arrested at G0/G1 with enhancing Cyclin D1/CDK4 and decreasing Cyclin A/CDK2 expression. Inhibition of autophagy abrogated APMD-induced cell cycle arrest. Furthermore, the inflammation regulation network of matrix metalloproteinase (MMP)-2, MMP-9, MAPKs and NF-κB pathways were activated by APMD. Rat periodontal models confirmed that APMD induced alveolar bone resorption, increased inflammatory infiltrates, and degraded collagen fibers through RAGE and PI3K. APMD-induced autophagy, G0/G1 arrest, pro-inflammatory signals activating and periodontal destruction were reversed by RAGE knockdown while aggravated by PI3K inhibitor. This study provides the first evidence that APMD bind to RAGE to regulate autophagy and cell cycle of PDLCs through the PI3K/AKT/mTOR pathway, thereby promoting periodontal destruction.

Erythropoietin Activates Autophagy to Regulate Apoptosis and Angiogenesis of Periodontal Ligament Stem Cells via the Akt/ERK1/2/BAD Signaling Pathway under Inflammatory Microenvironment

Background. Angiogenic tissue engineering is a vital problem waiting to be settled for periodontal regeneration. Erythropoietin, a multieffect cytokine, has been reported as a protective factor for cell fate. According to our previous study, erythropoietin has a significantly angiogenic effect on periodontal ligament stem cells. To further explore its potential effects and mechanism, we studied biological behaviors of periodontal ligament stem cells under inflammatory microenvironment induced by different concentrations (0, 10, 20, 50, and 100 ng/mL) of tumor necrosis factor-α (TNF-α) and examined how different concentrations (0, 5, 10, 20, and 50 IU/mL) of erythropoietin changed biological behaviors of periodontal ligament stem cells. Materials and Methods. Cell Counting Kit-8 was used for cell proliferation assay. Annexin V-PI-FITC was used for cell apoptosis through flow cytometry. Matrigel plug was adopted to measure the angiogenic capacity in vitro. RNA sequencing was used to detect the downstream signaling pathway. Quantitative real-time polymerase chain reaction was conducted to examine mRNA expression level. Western blot and immunofluorescence were applied to testify the protein expression level. Results. Periodontal ligament stem cells upregulated apoptosis and suppressed autophagy and angiogenesis under inflammatory microenvironment. Erythropoietin could activate autophagy to rescue apoptosis and angiogenesis levels of periodontal ligament stem cells through the Akt/Erk1/2/BAD signaling pathway under inflammatory microenvironment. Conclusions. Erythropoietin could protect periodontal ligament stem cells from inflammatory microenvironment, which provided a novel theory for periodontal regeneration.

Lactate inhibits osteogenic differentiation of human periodontal ligament stem cells via autophagy through the MCT1-mTOR signaling pathway

BACKGROUND

Periodontal ligament stem cells (PDLSCs) play a crucial role in periodontal bone regeneration. Lactate used to be considered a waste product of glucose metabolism. In recent years, a few pieces of evidence revealed its roles in regulating the osteogenic differentiation of stem cells, but the standpoints were controversial. This study aims to investigate the effects and the mechanisms of lactate on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs).

METHODS

The hPDLSCs were treated with different concentrations of lactic acid and lactate to differentiate the effects of the acidic PH and ion lactate. Proliferation and cytotoxicity were measured by Cell Counting Kit-8 (CCK8) assay and Live/Dead assay. The osteogenic differentiation of hPDLSCs was analyzed by alizarin red staining, alkaline phosphatase (ALP) staining, and then osteogenic proteins and genes were measured by western blot and reverse transcription-quantitative PCR (qRT-PCR). To investigate the potential signaling pathways, MCT1 inhibitor, G-protein inhibitors, and rapamycin were used, and then autophagy-related proteins and osteogenic proteins were measured by western blot.

RESULTS

The inhibition of lactic acid on the osteogenic differentiation of hPDLSCs was more significant than lactate at the same concentration. Lactate inhibited the expression of ALP which can be rescued by Gα inhibitor. Alizarin red staining, the protein expression levels of osteocalcin (OCN), osteoprotegerin (OPN), osterix (OSX), and beclin1, LC3-II/LC3-I were decreased by lactate and partly rescued by MCT1 inhibitor. Rapamycin restored the protein expression levels of beclin1, LC3-II/LC3-I and OCN, OPN, OSX under the high lactate conditions.

CONCLUSIONS

Lactate inhibits the expression of ALP via Gα subunit signaling, and inhibits mineralized nodules formation and the expression of osteogenic-related proteins via reducing autophagy through the MCT1-mTOR signaling pathway.

Metabolomics Research in Periodontal Disease by Mass Spectrometry

Periodontology is a newer field relative to other areas of dentistry. Remarkable progress has been made in recent years in periodontology in terms of both research and clinical applications, with researchers worldwide now focusing on periodontology. With recent advances in mass spectrometry technology, metabolomics research is now widely conducted in various research fields. Metabolomics, which is also termed metabolomic analysis, is a technology that enables the comprehensive analysis of small-molecule metabolites in living organisms. With the development of metabolite analysis, methods using gas chromatography–mass spectrometry, liquid chromatography–mass spectrometry, capillary electrophoresis–mass spectrometry, etc. have progressed, making it possible to analyze a wider range of metabolites and to detect metabolites at lower concentrations. Metabolomics is widely used for research in the food, plant, microbial, and medical fields. This paper provides an introduction to metabolomic analysis and a review of the increasing applications of metabolomic analysis in periodontal disease research using mass spectrometry technology.

Autophagy-Related Genes Predict the Progression of Periodontitis Through the ceRNA Network

Purpose

The goal of this study was to identify the crucial autophagy-related genes (ARGs) in periodontitis and construct mRNA-miRNA-lncRNA networks to further understand the pathogenesis of periodontitis.

Methods

We used the Gene Expression Omnibus (GEO) database and Human Autophagy Database (HADb) to identify differentially expressed mRNAs, miRNAs, and ARGs. These ARGs were subjected to Gene Ontology (GO), KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway, and PPI (protein–protein interaction) network analysis. Two databases (miRDB and StarBase v2.0) were used to reverse-predict miRNAs while the miRNA-lncRNA interaction was predicted using the StarBase v2.0 and LncBase Predicted v.2 databases. After excluding the lncRNAs only present in the nucleus, a competing endogenous RNA (ceRNA) network was built. Finally, we used quantitative real-time PCR (qRT-PCR) to confirm the levels of mRNA expression in the ceRNA network.

Results

The differential expression analysis revealed 10 upregulated and 10 downregulated differentially expressed ARGs. After intersecting the reverse-predicted miRNAs with the differentially expressed miRNAs, a ceRNA network consisting of 4 mRNAs (LAMP2, NFE2L2, NCKAP1, and EGFR), 3 miRNAs (hsa-miR-140-3p, hsa-miR-142-5p, and hsa-miR-671-5p), and 30 lncRNAs was constructed. In addition, qRT-PCR results revealed that EGFR expression was downregulated in diseased gingival tissue of periodontitis patients.

Conclusion

Four autophagy-related genes, especially EGFR, may play a key role in periodontitis progression. The novel ceRNA network may aid in elucidating the role and the mechanism of autophagy in periodontitis, which could be important in developing new therapeutic options.

Nicotine regulates autophagy of human periodontal ligament cells through α7 nAchR that promotes secretion of inflammatory factors IL-1β and IL-8

Background

Nicotine is an important risk factor and the main toxic component associated with periodontitis. However, the mechanism of nicotine induced periodontitis is not clear. To investigated the mechanism through which nicotine regulates autophagy of human periodontal ligament cells (hPDLCs) through the alpha7 nicotinic acetylcholine receptor (α7 nAChR) and how autophagy further regulates the release of IL-1β and IL-8 secretion in hPDLCs.

Methods

HPDLCs were obtained from root of extracted teeth and pre-incubated in alpha-bungarotoxin (α-BTX) or 3-Methyladenine (3-MA), followed by culturing in nicotine. We used a variety of experimental detection techniques including western blotting, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), transmission electron microscopy (TEM) and RT-qPCR to assess the expression of the LC3 protein, autolysosome, and release of IL-1β and IL-8 from hPDLCs.

Results

Western blots, immunofluorescence and TEM results found that the nicotine significantly increased the autophagy expression in hPDLCs that was time and concentration dependent and reversed by α-BTX treatment (p < 0.05). RT-qPCR and ELISA results revealed a noticeable rise in the release of inflammatory factors IL-1β and IL-8 from hPDLCs in response to nicotine. RT-qPCR and ELISA results showed that nicotine can significantly up-regulate the release of inflammatory factors IL-1β and IL-8 in hPDLCs, and this effect can be inhibited by 3-MA (p < 0.05).

Conclusions

Nicotine regulated autophagy of hPDLCs through α7 nAChR and in turn the regulation of the release of inflammatory factors 1L-1β and 1L-8 by hPDLCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01894-5.

Effect of endoplasmic reticulum stress-induced apoptosis in the role of periodontitis on vascular calcification in a rat model

The present study aimed to investigate the mechanism(s) through which endoplasmic reticulum stress (ERS)-induced apoptosis, in the role of periodontitis, affects vascular calcification. Rat models of periodontitis, vascular calcification, periodontitis-vascular calcification, and a normal group were established. Cardiovascular tissues were obtained, and hematoxylin-eosin staining was applied to demonstrate the morphological changes in vascular tissues. Immunohistochemical staining was applied to analyze apoptosis in cardiovascular tissues. The expression levels of apoptotic factor cysteinyl aspartate specific proteinase 3 (Caspase-3), ERS-induced apoptotic factors glucose-regulated protein 78 (GRP78), 94 (GRP94), and ERS-induced apoptosis pathways Caspase-12, C/EBP homologous protein (CHOP), and c-Jun N-terminal kinase (JNK) were analyzed and compared. Hematoxylin-eosin staining revealed that the arterial layers in the normal group were structurally intact. The structural damage to the aortic wall gradually aggravated from the periodontitis group to the vascular calcification group to the combined group. The immunohistochemistry results showed Caspase-3, GRP78, GRP94, and ERS-induced apoptosis pathways in the cardiovascular tissues cells in the periodontitis group, vascular calcification group, and combined group. The Caspase-3, GRP78, GRP94, and CHOP expression levels in the combined group were significantly higher than that in the normal group (P < 0.05); however, the Capase-12 and JNK expression levels in the four groups exhibited no significant differences (P > 0.05). Apoptosis induced by ERS is involved in the effect of periodontitis on vascular calcification and might be mainly achieved through the activation of the CHOP transcription pathway.

Autophagy in Gastric Mucosa: The Dual Role and Potential Therapeutic Target

The incidence of stomach diseases is very high, which has a significant impact on human health. Damaged gastric mucosa is more vulnerable to injury, leading to bleeding and perforation, which eventually aggravates the primary disease. Therefore, the protection of gastric mucosa is crucial. However, existing drugs that protect gastric mucosa can cause nonnegligible side effects, such as hepatic inflammation, nephritis, hypoacidity, impotence, osteoporotic bone fracture, and hypergastrinemia. Autophagy, as a major intracellular lysosome-dependent degradation process, plays a key role in maintaining intracellular homeostasis and resisting environmental pressure, which may be a potential therapeutic target for protecting gastric mucosa. Recent studies have demonstrated that autophagy played a dual role when gastric mucosa exposed to biological and chemical factors. More indepth studies are needed on the protective effect of autophagy in gastric mucosa. In this review, we focus on the mechanisms and the dual role of various biological and chemical factors regulating autophagy, such as Helicobacter pylori, virus, and nonsteroidal anti-inflammatory drugs. And we summarize the pathophysiological properties and pharmacological strategies for the protection of gastric mucosa through autophagy.