Role of ferroptosis-related genes in periodontitis based on integrated bioinformatics analysis

Helium cold atmospheric pressure plasma reduces erastin induced inflammation and ferroptosis in human gingival fibroblasts

Oral soft tissue damage can lead to hard tissue damage in the oral cavity, such as periodontal lesions, periapical disorders, cysts, and oral tumors. Cold plasma is known to alleviate inflammation and oxidative stress and promote tissue regeneration, yet the effects of helium plasma on human gingival cells remain poorly understood. In this study, we examined whether helium (He) cold atmospheric pressure plasma (CAP) can induce anti-inflammatory and anti-ferroptotic effects in oral soft tissues by ionizing He gas. Erastin treatment followed by He CAP exposure in human gingival fibroblast-1 (HGF-1) cells reduced the mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), tumor necrosis factor-α (TNFα), and interleukin-6 (IL-6), which are linked to inflammatory responses. Additionally, He CAP exposure decreased nuclear receptor coactivator 4 (NCOA4) expression and increased glutathione peroxidase 4 (GPX4) expression. Furthermore, mitochondrial membrane potential was restored by increased voltage-dependent anion channel 1 (VDAC1) expression, and reactive oxygen species (ROS) levels in mitochondria and cytoplasm were reduced. These results suggest that He CAP exposure may be associated with modulation of mitochondrial ROS production and reduction of inflammation and ferroptosis, but whether mitochondrial repair contributes to these effects requires further investigation.

Programmed Cell Death Tunes Periodontitis

OBJECTIVE

To review current knowledge of the various processes of programmed cell death and their roles in immunoregulation in periodontitis.

METHODS

Relevant literature in the PubMed, Medline, and Scopus databases was searched, and a narrative review was performed. Programmed cell death and the regulation of its various pathways implicated in periodontal infection were reviewed.

RESULTS

Multicellular organisms dispose of unnecessary or damaged cells via programmed cell death. Programmed cell death lies at the core of the balance of cell death and survival in pathological progress and infection. Periodontitis is a complex infectious disease involving virulence factors of periodontal pathogens and tightly regulated immune responses of the host. Different types of programmed cell death can play opposite roles in periodontitis or exert their action combinatorially.

CONCLUSION

The coordinated system of various programmed cell death pathways and the extensive crosstalk among them play a fundamental role in the pathophysiology of periodontitis. Illuminating the precise roles and mechanisms of programmed cell death in periodontitis could open up novel therapeutic approaches.

Identification of JNK-JUN-NCOA axis as a therapeutic target for macrophage ferroptosis in chronic apical periodontitis

Objectives: This study aimed to investigate the involvement of macrophage ferroptosis in chronic apical periodontitis (CAP) and determine if blocking JNK/JUN/NCOA4 axis could alleviate CAP by regulating macrophage ferroptosis. Materials and Methods: Firstly, the in vitro models of apical periodontitis (AP) and in vivo models of CAP, including clinical specimens and rats' periapical lesions, were utilized to investigate the role of macrophage ferroptosis in CAP by detecting the ferroptosis related factors. The activation of the JNK/JUN/NCOA4 axis was observed in CAP in vivo models. Pearson's correlation and linear tendency tests were employed to analyze the correlation between the JNK/JUN/NCOA4 axis and macrophage ferroptosis during CAP progression. Subsequently, the JNK/JUN/NCOA4 axis was blocked by SP600125, and the alterations in ferroptosis associated variables and inflammation levels in macrophages were evaluated. Results: The in vitro AP model demonstrated that macrophage ferroptosis mainly occurred during the late phase of inflammatory conditions, with the reduction of GPX4, SLC7A11 and the increase of TFR1 in macrophages. Additionally, a higher accumulation of iron was observed in the periapical lesions derived from clinic samples and animal model. Furthermore, we found that differences in macrophage ferroptosis levels within periapical lesions corresponded altered activation of JNK/JUN/NCOA4 axis. Significantly, the inhibition of JNK/JUN/NCOA4 axis reduced the aforementioned changes and inflammation levels induced by E. coli LPS in macrophages. Conclusions: The occurrence of ferroptosis in macrophages contributes to the development of CAP. Targeting the JNK/JUN/NCOA4 axis is an effective therapeutic strategy to rescue the periapical lesions from inflammation due to its anti-macrophage ferroptosis function. Consequently, the current study provides support for further investigation on the JNK/JUN/NCOA4 axis as a targeted signaling pathway for CAP treatment.

The Potential Regulatory Role of Ferroptosis in Orthodontically Induced Inflammatory Root Resorption

People, in increasing numbers, are seeking orthodontic treatment to correct malocclusion, while some of them are suffering from orthodontically induced inflammatory root resorption (OIIRR). Recent evidence suggests that the immune-inflammatory response occurring during bone remodeling may be responsible for OIIRR. Ferroptosis, a new type of programmed cell death (PCD), has been found to have a close interrelation with inflammation during disease progression. While ferroptosis has been extensively studied in bone-related diseases, its role in OIIRR is poorly understood. Considering that the tooth root shares a lot of similar characteristics with bone, it is reasonable to hypothesize that ferroptosis contributes to the development of OIIRR. Nevertheless, direct evidence supporting this theory is currently lacking. In this review, we introduced ferroptosis and elucidated the mechanisms underlying orthodontic tooth movement (OTM) and OIIRR, with a special focus on the pivotal role inflammation plays in these processes. Additionally, we covered recent research exploring the connections between inflammation and ferroptosis. Lastly, we emphasized the important regulatory function of ferroptosis in bone homeostasis. Further investigations are required to clarify the modulation mechanisms of ferroptosis in OIIRR and to develop novel and potential therapeutic strategies for the management of OIIRR.

ALDH2 alleviates inflammation and facilitates osteogenic differentiation of periodontal ligament stem cells in periodontitis by blocking ferroptosis via activating Nrf2

This paper elucidated the effects and mechanisms of aldehyde dehydrogenase 2 (ALDH2) on periodontitis. Rat model of periodontitis and periodontal ligament stem cell (PDLSC) model of periodontitis were constructed. PDLSC were transfected by ALDH2 overexpression vectors, and then treated by ML385 (Nrf2 inhibitor), ferrostatin-1 (ferroptosis inhibitor) and FIN56 (ferroptosis inducer), respectively. ALDH2, nuclear factor erythroid 2-related factor 2 (Nrf2) and glutathione peroxidase 4 (GPX4) proteins was evaluated by immunohistochemistry and Western blot. Ferroptosis-related factors, including Fe2+ and glutathione (GSH), were assessed by commercial kits. Pro-inflammatory factors (interleukin-6 [IL-6] and tumor necrosis factor-α [TNF-α]) and osteogenic differentiation-related proteins (osteocalcin [OCN] and runt-related transcription factor 2 [RUNX2]) were scrutinized by commercial kits and Western blot. In both periodontal tissues of periodontitis rats and PDLSC model of periodontitis, down-regulated ALDH2, Nrf2, GPX4 and GSH, but elevated Fe2+ level was discovered. ALDH2 overexpression in PDLSC resulted in an increase in Nrf2 expression. In PDLSC model of periodontitis, ALDH2 increased GPX4 and GSH levels, decreased Fe2+, IL-6 and TNF-α levels, and elevated OCN and RUNX2 expression. However, these effects of ALDH2 were counteracted by ML385. Additionally, the suppression of ALDH2 on IL-6 and TNF-α levels and promotion of it on OCN and RUNX2 expression in PDLSC model of periodontitis was further intensified by ferrostatin-1, but reversed by FIN56. ALDH2 may alleviate inflammation and facilitate osteogenic differentiation of PDLSC in periodontitis by hindering ferroptosis via activating Nrf2, suggesting it to be a promising candidate for treating periodontitis.

Lipotoxicity: The missing link between diabetes and periodontitis?

Lipotoxicity refers to the accumulation of lipids in tissues other than adipose tissue (body fat). It is one of the major pathophysiological mechanisms responsible for the progression of diabetes complications such as non-alcoholic fatty liver disease and diabetic nephropathy. Accumulating evidence indicates that lipotoxicity also contributes significantly to the toxic effects of diabetes on periodontitis. Therefore, we reviewed the current in vivo, in vitro, and clinical evidence of the detrimental effects of lipotoxicity on periodontitis, focusing on its molecular mechanisms, especially oxidative and endoplasmic reticulum stress, inflammation, ceramides, adipokines, and programmed cell death pathways. By elucidating potential therapeutic strategies targeting lipotoxicity and describing their associated mechanisms and clinical outcomes, including metformin, statins, liraglutide, adiponectin, and omega-3 PUFA, this review seeks to provide a more comprehensive and effective treatment framework against diabetes-associated periodontitis. Furthermore, the challenges and future research directions are proposed, aiming to contribute to a more profound understanding of the impact of lipotoxicity on periodontitis.

Effects of the ferroptosis inducer erastin on osteogenic differentiation and biological pathways of primary osteoblasts

BACKGROUND

Periodontitis is a chronic destructive inflammatory disease exacerbated by osteoblast dysfunction. Ferroptosis has emerged as a significant factor that could contribute to the pathological changes observed in periodontitis. However, the impact of ferroptosis on osteogenic differentiation and gene expression patterns of primary osteoblasts remain elusive.

METHODS

In this study, osteoblasts were osteogenically induced for specific durations with and without the ferroptosis inducer erastin. Subsequently, cell proliferation, ferroptosis-related molecules, and osteogenic differentiation capacity were assessed. Furthermore, the differences in transcriptome expression following erastin treatment were analyzed by RNA sequencing.

RESULTS

The results demonstrated that erastin treatment induced ferroptosis, resulting in suppressed cell proliferation and impaired osteogenic differentiation. Transcriptomic analysis revealed significant alterations in processes such as hydrogen peroxide catabolism, response to lipid peroxidation, and metal iron binding, as well as BMP receptor activity and collagen type XI trimer.

CONCLUSION

The ferroptosis inducer erastin inhibited osteoblast proliferation and differentiation. Our study provides novel insights into the effect of ferroptosis on osteogenesis, suggesting that targeting ferroptosis may present a promising approach in the treatment of periodontitis.

Nuclear and cytoplasmic specific RNA binding proteome enrichment and its changes upon ferroptosis induction

The key role of RNA-binding proteins (RBPs) in posttranscriptional regulation of gene expression is intimately tied to their subcellular localization. Here, we show a subcellular-specific RNA labeling method for efficient enrichment and deep profiling of nuclear and cytoplasmic RBPs. A total of 1221 nuclear RBPs and 1333 cytoplasmic RBPs were enriched and identified using nuclear/cytoplasm targeting enrichment probes, representing an increase of 54.4% and 85.7% compared with previous reports. The probes were further applied in the omics-level investigation of subcellular-specific RBP-RNA interactions upon ferroptosis induction. Interestingly, large-scale RBPs display enhanced interaction with RNAs in nucleus but reduced association with RNAs in cytoplasm during ferroptosis process. Furthermore, we discovered dozens of nucleoplasmic translocation candidate RBPs upon ferroptosis induction and validated representative ones by immunofluorescence imaging. The enrichment of Tricarboxylic acid cycle in the translocation candidate RBPs may provide insights for investigating their possible roles in ferroptosis induced metabolism dysregulation.

Role of ferroptosis in periodontitis: An animal study in rats

OBJECTIVE

This study aimed to investigate (1) the temporal pattern of ferroptosis, an iron-dependent cell death, in ligation-induced rat periodontitis and (2) the effect of ferrostatin-1, a ferroptosis inhibitor, on the model.

BACKGROUND

Ferroptosis may contribute to various diseases. However, the role of ferroptosis in periodontitis is still fully understood.

METHODS

In the first experiment, 25 rats with ligation-induced periodontitis were sacrificed on days 0, 1, 2, 7, and 10. Gingivae were obtained to determine tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and ferroptotic biomarkers, including solute carrier family 3 member 2 (SLC3A2) and solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (Gpx4), via immunoblotting. Using microcomputed tomography (μCT) and histology, the periodontal soft and hard tissue lesions, including dental alveolar bone crest level, bony characteristics of the surrounding alveolus, periodontal tissue inflammation, and periodontal tissue losses, were evaluated. In study two, 16 rats with induced periodontitis were grouped according to ferrostatin-1 treatment. The rats were intraperitoneally injected with solvent or ferrostatin-1 (1.5 mg/kg/day) 1 day before ligation and sacrificed on days 7 and 10. Gingival protein changes and periodontal tissue damage were also examined.

RESULTS

In study one, SLC3A2/SLC7A11 and Gpx4 decreased since day 1; however, TNF-α/IL-1β increased on days 7 and 10. Moreover, the μCT/histology revealed resorptive bony characteristics, inflamed gingival tissue, and periodontal attachment loss. In study two, ferrostatin-1-injected rats exhibited significantly increased SLC3A2/SLC7A11 and Gpx4 but decreased TNF-α/IL-1β than vehicle rats. They also revealed lessened bone resorption, tissue inflammation, and attachment loss.

CONCLUSION

This study highlights the role of ferroptosis, via the system Xc/Gpx4 pathway, in experimental periodontitis and may serve as a regulatory strategy.

Periodontitis contributes to COPD progression via affecting ferroptosis

BACKGROUND

Periodontitis has emerged as a potential risk factor for chronic obstructive pulmonary disease (COPD). However, the precise mechanism through which periodontitis influences the progression of COPD requires further investigation. Ferroptosis is one of the crucial pathogenesis of COPD and recent researches suggested that periodontitis was associated with ferroptosis. Nonetheless, the relationship among periodontitis, COPD and ferroptosis remains unclear. This study aimed to elucidate whether periodontitis contributes to COPD exacerbation and to assess the potential impact of ferroptosis on periodontitis affecting COPD.

METHODS

The severity of COPD was assessed using Hematoxylin and eosin (H&E) staining and lung function tests. Iron assays, malondialdehyde (MDA) measurement and RT-qPCR were used to investigate the potential involvement of ferroptosis in the impact of periodontitis on COPD. Co-cultures of periodontitis associated pathogen Phophyromonas gingivalis (P. gingivalis) and lung tissue cells were used to evaluate the effect of P. gingivalis on inducing the ferroptosis of lung tissue via RT-qPCR analysis. Clinical Bronchoalveolar Lavage Fluid (BALF) samples from COPD patients were collected to further validate the role of ferroptosis in periodontal pathogen-associated COPD.

RESULTS

Periodontitis aggravated the COPD progression and the promotion was prolonged over time. For the first time, we demonstrated that periodontitis promoted the ferroptosis-associated iron accumulation, MDA contents and gene expressions in the COPD lung with a time-dependent manner. Moreover, periodontitis-associated pathogen P. gingivalis could promote the ferroptosis-associated gene expression in single lung tissue cell suspensions. Clinical BALF sample detection further indicated that ferroptosis played essential roles in the periodontal pathogen-associated COPD.

CONCLUSION

Periodontitis could contribute to the exacerbation of COPD through up-regulating the ferroptosis in the lung tissue.

Identification and characterization of the ferroptosis-related ceRNA network in irreversible pulpitis

Background

The role of ferroptosis in irreversible pulpitis (IP) remains unclear. The competing endogenous RNA (ceRNA) theory that has been widely investigated is rarely used studied in IP. Hub lncRNAs selected from a ceRNA network may provide a novel hypothesis for the interaction of ferroptosis and IP.

Methods

Differentially expressed genes (DEGs) were intersected with 484 ferroptosis markers to identify differentially expressed ferroptosis-related genes (DE-FRGs). Functional analysis and protein-protein interaction (PPI) networks were constructed to reveal the functions of DE-FRGs. Then, coexpression analyses were conducted between DE-FRGs and DElncRNAs to define ferroptosis-related DElncRNAs (FR-DElncRNAs). Predictions of DE-FRG- and FR-DElncRNA-related miRNAs were obtained, and members of both groups were selected. Additionally, two ceRNA networks consisting of FR-DElncRNAs, miRNAs and DE-FRGs from upregulated and downregulated groups were built. Finally, the hub lncRNAs of the ceRNA networks were used for immuno-infiltration analysis and qPCR verification.

Results

According to the results of PCA and clustering analysis, 5 inflamed and 5 healthy pulp tissue samples were selected for analysis. The intersection of DEGs with 484 ferroptosis marker genes identified 72 DE-FRGs. The response to stimulus, cellular process, signaling, localization, and biological regulation pathways related to DE-FRGs were enriched. In total, 161 downregulated and 40 upregulated FR-DElncRNAs were chosen by coexpression analysis for further investigation. The MultimiR package and starBase were used to predict miRNAs of DE-FRGs and FR-DElncRNAs, respectively. The upregulated ceRNA network contained 2 FR-DElncRNAs (↑), 19 miRNAs (↓) and 22 DE-FRGs (↑). The downregulated network contained 44 FR-DElncRNAs (↓), 251 miRNAs (↑) and 10 DE-FRGs (↓). Six hub lncRNAs were identified based on the MCC method (LUCAT1 and AC106897.1 ↑; LINC00943, AL583810.1, AC068888.1, and AC125257.1↓). In addition, strong relationships between hub lncRNAs and immune cells were shown by immune infiltration analysis. Finally, validated by qPCR assays of the pulp tissue of IP patients, the expression levels in clinical samples were consistent with the microarray data.

Conclusion

Two ceRNA networks were comprehensively constructed, and 6 hub lncRNAs were identified. These genes provide novel insights into the relationship between ferroptosis and IP. Intriguingly, the LINC00943/hsa-miR-29a-3p/PDK4 axis was deemed to be the key node in this network.

Identification of ferroptosis, necroptosis, and pyroptosis-associated genes in periodontitis-affected human periodontal tissue using integrated bioinformatic analysis

Introduction: Periodontitis is a chronic inflammatory oral disease that destroys soft and hard periodontal support tissues. Multiple cell death modes including apoptosis, necroptosis, pyroptosis, and ferroptosis play a crucial role in the pathogenicity of inflammatory diseases. This study aimed to identify genes associated with ferroptosis, necroptosis, and pyroptosis in different cells present in the periodontium of periodontitis patients. Methods: Gingival tissues' mRNA sequencing dataset GSE173078 of 12 healthy control and 12 periodontitis patients' and the microarray dataset GSE10334 of 63 healthy controls and 64 periodontitis patients' were obtained from Gene Expression Omnibus (GEO) database. A total of 910 differentially expressed genes (DEGs) obtained in GSE173078 were intersected with necroptosis, pyroptosis, and ferroptosis-related genes to obtain the differential genes associated with cell death (DCDEGs), and the expression levels of 21 differential genes associated with cell death were verified with dataset GSE10334. Results: Bioinformatic analysis revealed 21 differential genes associated with cell death attributed to ferroptosis, pyroptosis, and necroptosis in periodontitis patients compared with healthy controls. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses revealed that 21 differential genes associated with cell death were related to various cellular and immunological pathways including inflammatory responses, necroptosis, and osteoclast differentiation. Additionally, the single-cell RNA (scRNA) sequencing data GSE171213 of 4 healthy controls and 5 periodontitis patients' periodontal tissue was analyzed to obtain cell clustering and cell types attributed to differential genes associated with cell death. We found that among 21 DCDEGs, SLC2A3, FPR2, TREM1, and IL1B were mainly upregulated in neutrophils present in the periodontium of periodontitis patients. Gene overlapping analysis revealed that IL-1B is related to necroptosis and pyroptosis, TREM1 and FPR2 are related to pyroptosis, and SLC2A3 is related to ferroptosis. Finally, we utilized the CIBERSORT algorithm to assess the association between DCDEGs and immune infiltration phenotypes, based on the gene expression profile of GSE10334. The results revealed that the upregulated SLC2A3, FPR2, TREM1, and IL1B were positively correlated with neutrophil infiltration in the periodontium. Discussion: The findings provide upregulated SLC2A3, FPR2, TREM1, and IL1B in neutrophils as a future research direction on the mode and mechanism of cell death in periodontitis and their role in disease pathogenicity.

Ferroptosis: A New Development Trend in Periodontitis

Periodontitis is a chronic inflammatory disease associated with bacterial biofilm. It is characterized by loss of periodontal support tissue and has long been considered as a "silent disease". Because it is difficult to prevent and has a health impact that can not be ignored, researchers have been focusing on a mechanism-based treatment model. Ferroptosis is an iron-dependent regulatory form of cell death, that directly or indirectly affects glutathione peroxidase through different signaling pathways, resulting in a decrease in cell antioxidant capacity, accumulation of reactive oxygen species and lipid peroxidation, which cause oxidative cell death and tissue damage. Recently, some studies have proven that iron overload, oxidative stress, and lipid peroxidation exist in the process of periodontitis. Based on this, this article reviews the relationship between periodontitis and ferroptosis, in order to provide a theoretical reference for future research on the prevention and treatment of periodontal disease.

Identification of cross-talk pathways and ferroptosis-related genes in periodontitis and type 2 diabetes mellitus by bioinformatics analysis and experimental validation

Purpose

There is a bidirectional relationship between periodontitis and type 2 diabetes mellitus (T2DM). The aim of this study was to further explore the pathogenesis of this comorbidity, screen out ferroptosis-related genes involved in the pathological process, and predict potential drug targets to develop new therapeutic strategies.

Methods

Common cross-talk genes were identified from periodontitis datasets (GSE16134, GSE10334 and GSE106090) and T2DM databases (DisGeNET and GeneCard). Then, GO and KEGG enrichment analyses, PPI network analysis and hub gene identification were performed. The association between ferroptosis and periodontitis with T2DM was investigated by Pearson correlation analysis. Core ferroptosis-related cross-talk genes were identified and verified by qRT-PCR. Potential drugs targeting these core genes were predicted via DGIDB.

Results

In total, 67 cross-talk genes and two main signalling pathways (immuno-inflammatory pathway and AGE-RAGE signalling pathway) were identified. Pearson correlation analysis indicated that ferroptosis served as a crucial target in the pathological mechanism and treatment of periodontitis with T2DM. IL-1β, IL-6, NFE2L2 and ALOX5 were identified as core ferroptosis-related genes and the qRT-PCR detection results were statistically different. In total, 13 potential drugs were screened out, among which, Echinacea and Ibudilast should be developed first.

Conclusions

This study contributes to a deeper understanding of the common pathogenesis of periodontitis and T2DM and provides new insights into the role of ferroptosis in this comorbidity. In addition, two drugs with potential clinical application value were identified. The potential utility of these drugs requires further experimental investigation.