High serum iron markers are associated with periodontitis in post-menopausal women: A population-based study (NHANES III)

Associations of dietary antioxidant intake with periodontal health among US adults: An exploratory mediation analysis via mitochondrial function

AIM

To assess the relationship between dietary antioxidant intake and periodontal health in US adults and the potential role of mitochondrial function.

MATERIALS AND METHODS

We performed a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Dietary antioxidant intake was evaluated using three diet-related indices: dietary oxidative balance score (DOBS), dietary total antioxidant capacity (DTAC) of antioxidant vitamins and composite dietary antioxidant index (CDAI). Periodontal parameters included attachment loss (AL) and probing pocket depth (PPD). Mitochondrial dysfunction was assessed using the methylmalonic acid (MMA) level. Weighted multivariable linear regression analyses were employed to investigate the association between dietary antioxidant intake and periodontal status. Additionally, exploratory mediation analyses were conducted to determine the mediating effect of MMA on the association.

RESULTS

Totally, 5520 participants were included in our study. Participants with higher DOBS and DTAC scores had lower mean AL/PPD and MMA values. CDAI was negatively associated with mean AL and PPD. Furthermore, MMA mediated 9.4% and 4.9% of the associations between DOBS and mean AL and mean PPD, respectively. MMA also accounted for 7.2% and 3.3% of the association between DTAC and mean AL and PPD, respectively.

CONCLUSIONS

The findings support that dietary antioxidant intake helps in improving periodontal health, possibly and partially by enhancing mitochondrial function.

Research progress on the regulatory cell death of osteoblasts in periodontitis

Periodontitis is a chronic inflammatory disease characterized by progressive destruction of alveolar bone. The most critical mechanism underlying alveolar bone destruction is the imbalance of bone homeostasis, where osteoblast-mediated bone matrix synthesis plays an important role in regulating bone homeostasis. Regulatory cell death is instrumental in both the inflammatory microenvironment and the regulation of bone homeostasis. Chronic inflammation, oxidative stress, and other factors can be directly involved in mitochondrial and death receptor-mediated signaling pathways, modulating B-cell lymphoma 2 (Bcl-2) family proteins and cysteine aspartic acid specific protease (caspase) activity, thereby affecting osteoblast apoptosis and alveolar bone homeostasis. Chronic inflammation and cellular damage induce osteoblast necroptosis via the RIPK1/RIPK3/MLKL signaling pathway, exacerbating the inflammatory response and accelerating alveolar bone destruction. Stimuli such as pathogenic microorganisms and cellular injury may also activate caspase-1-dependent or independent signaling pathways and gasdermin D (GSDMD) family proteins, promoting osteoblast pyroptosis and releasing pro-inflammatory cytokines to mediate alveolar bone damage. Iron overload and lipid peroxidation in periodontitis can trigger ferroptosis in osteoblasts, impacting their survival and function, ultimately leading to bone homeostasis imbalance. This article focuses on the mechanism of periodontal disease affecting bone homeostasis through regulatory cell death, aiming to provide research evidence for the treatment of periodontitis and alveolar bone homeostasis imbalance.

Exploring the molecular mechanisms of ferroptosis-related genes in periodontitis: a multi-dataset analysis

PURPOSE

This study aims to elucidate the biological functions of ferroptosis-related genes in periodontitis, along with their correlation to tumor microenvironment (TME) features such as immune infiltration. It aims to provide potential diagnostic markers of ferroptosis for clinical management of periodontitis.

METHODS

Utilizing the periodontitis-related microarray dataset GSE16134 from the Gene Expression Omnibus (GEO) and a set of 528 ferroptosis-related genes identified in prior studies, this research unveils differentially expressed ferroptosis-related genes in periodontitis. Subsequently, a protein-protein interaction network was constructed. Subtyping of periodontitis was explored, followed by validation through immune cell infiltration and gene set enrichment analyses. Two algorithms, randomForest and SVM(Support Vector Machine), were employed to reveal potential ferroptosis diagnostic markers for periodontitis. The diagnostic efficacy, immune correlation, and potential transcriptional regulatory networks of these markers were further assessed. Finally, potential targeted drugs for differentially expressed ferroptosis markers in periodontitis were predicted.

RESULTS

A total of 36 ferroptosis-related genes (30 upregulated, 6 downregulated) were identified from 829 differentially expressed genes between 9 periodontitis samples and the control group. Subsequent machine learning algorithm screening highlighted 4 key genes: SLC1A5(Solute Carrier Family 1 Member 5), SLC2A14(Solute Carrier Family 1 Member 14), LURAP1L(Leucine Rich Adaptor Protein 1 Like), and HERPUD1(Homocysteine Inducible ER Protein With Ubiquitin Like Domain 1). Exploration of these 4 key genes, supported by time-correlated ROC analysis, demonstrated reliability, while immune infiltration results indicated a strong correlation between key genes and immune factors. Furthermore, Gene Set Enrichment Analysis (GSEA) was conducted for the four key genes, revealing enrichment in GO/KEGG pathways that have a significant impact on periodontitis. Finally, the study predicted potential transcriptional regulatory networks and targeted drugs associated with these key genes in periodontitis.

CONCLUSIONS

The ferroptosis-related genes identified in this study, including SLC1A5, SLC2A14, LURAP1L, and HERPUD1, may serve as novel diagnostic and therapeutic targets for periodontitis. They are likely involved in the occurrence and development of periodontitis through mechanisms such as immune infiltration, cellular metabolism, and inflammatory chemotaxis, potentially linking the ferroptosis pathway to the progression of periodontitis. Targeted drugs such as flurofamide, L-733060, memantine, tetrabenazine, and WAY-213613 hold promise for potential therapeutic interventions in periodontitis associated with these ferroptosis-related genes.

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.

Serum iron concentration and leptin inversely relate, partially mediated by body mass index in American adults

Iron metabolism and leptin are interconnected, and both link with obesity. In this cross-sectional study, we hypothesized that serum iron markers associate with leptin, with body mass index (BMI) acting as a mediator, confounder, and effect modifier in this relationship. We analyzed data from the National Health and Nutrition Examination Survey III, with a focus on serum iron markers and leptin. The relationship between serum iron markers and leptin was determined by multiple linear regression. The bootstrap method was used to investigate the mediating effect of BMI on this association. Among 3888 American adults, serum iron and transferrin saturation showed a negative association with leptin (log2-transformed) (β: -0.010, 95% confidence interval [CI], -0.013 to -0.006, P < .001; β: -0.006, 95% CI, -0.008 to -0.004, P < .001). Total iron-binding capacity was positively associated with the serum concentration of leptin (log2-transformed) (β: 0.002, 95% CI, 0-0.004, P = .0292). Sex, BMI, and body fat percentage significantly influenced these associations. Notably, the association between the iron markers and leptin diminished in individuals with a BMI ≥30 kg/m2. There was no observable relationship between leptin and serum ferritin concentrations. BMI mediated 4.81% of the serum iron-leptin association, with no mediation of body fat percentage. Our study identified a link between serum iron and leptin, with BMI as a mediating factor. In clinical settings, it is vital to understand how treatments targeting iron metabolism can directly impact serum leptin concentration and the subsequent physiological changes.

Role of ferroptosis in Porphyromonas gingivalis-induced impairment of epithelial junction

Objectives

This study aims to clarify the effect of ferroptosis by P. gingivalis on periodontal epithelium impairment and potential mechanisms.

Materials and methods

The expression of epithelial junction proteins (CDH1, OCLN, ZO-1), FTL and GPX4 in healthy and periodontitis tissues was analyzed using bioinformatics analysis and validated in vivo. An in vitro model was constructed to evaluate ferroptosis by mitochondria morphology, content of iron and GSH, and level of lipid peroxidation, FTL, GPX4 and SLC7A11. The iron concentration was changed with iron chelator DFO and iron supplementation FAC. The epithelial impairment was assessed by protein expression. To investigate the mechanism, si-MYB (a negative transcription factor of SLC7A11) and GPX4 inhibitor RSL3 were employed.

Results

CDH1, OCLN, ZO-1 and GPX4 expression was decreased, while FTL expression was elevated in periodontitis tissues. Infected cells showed ferroptosis change of the mitochondria with higher level of lipid peroxidation, iron, FTL and lower level of GPX4, GSH, SLC7A11. FAC augmented ferroptosis and weakened epithelial junction, while DFO exhibited a counteractive effect. Silencing MYB rescued SLC7A11, GPX4 and epithelial junction proteins, which was hindered by RSL3.

Conclusions

Our study demonstrated that P. gingivalis weakened the oral epithelial barrier by causing ferroptosis via inhibiting SLC7A11/GSH/GPX4 axis.

Serum iron and ferritin levels in female patients with gingivitis and periodontitis

AIM

The aim of the study was to compare serum ferritin and iron levels and periodontal status in pre- and post-menopausal female patients.

MATERIALS AND METHODS

A total of 108 systemically healthy patients were included in the study, 63 patients in the pre-menopause group and 45 patients in the post-menopause group. The periodontal diagnosis was made according to the new periodontal disease classification of the American Academy of Periodontology and the European Federation of Periodontology Serum Iron (μg/dL) and Serum Ferritin (ng/mL) values were analysed in patients divided into groups according to menopausal status and periodontal status.

RESULT

The mean ferritin in pre-menopausal women (34.96 ± 27.87 ng/mL) was lower than the mean ferritin in post-menopausal women (64.24 ± 36.05 ng/mL), and this difference was found to be statistically significant (P<0.001). There was no statistically significant difference between the averages of iron and ferritin according to periodontal diagnosis in pre-menopausal women (P = 0.200 and P = 0.858). A statistically significant difference was found between serum ferritin averages according to periodontal diagnosis in post-menopausal women (P < 0.001). Serum ferritin at % Interdental bone loss = 0 in Post-M was 33.93 ± 8.65 ng/mL; 47.51 ± 16.17 ng/mL in Stage 1 periodontitis; 72.66 ± 18.12 ng/mL in Stage 2 periodontitis; It was found to be 87.4 ± 47.1 ng/mL in Stage 3-4 periodontitis.

CONCLUSION

Serum ferritin values might vary depending on the presence or severity of periodontitis in post-menopausal women.

Association between ethylene oxide exposure and periodontitis: a cross-sectional study from NHANES 2013-2014

BACKGROUND

Exposure to ethylene oxide (EO) induces inflammation and oxidative stress, which are the main mechanisms of periodontitis. However, the effect of EO on periodontal health is not unclear. In this study, we aimed to explore the relationship between EO exposure and the risk of periodontitis in general US adults.

METHODS

Data used in our study from the National Health and Nutritional Examination Survey (NHANES) 2013-2014. The EO biomarker, hemoglobin adduct of EO (HbEO), was measured in blood samples utilizing high-performance liquid chromatography-tandem mass spectrometry. Periodontitis category was defined by the CDC/AAP according to clinical periodontal parameters. Natural cubic spline, weight multivariable logistic regression analyses and subgroup analysis were used to explore the association between EO exposure and the risk of periodontitis.

RESULTS

A total of 1497 participants over the age of 30 were included in our study. A non-linear positive association with periodontitis was identified for HbEO levels. Participants in the highest tertile of HbEO levels were more likely to have poorer periodontal health compared to the lowest tertile (ORtertile3vs1 = 2.80, 95% CI: 1.85-4.24). Similar results were also found in different subgroups.

CONCLUSIONS

HbEO levels are positively associated with poor periodontal health in US adults. Additional longitudinal studies are necessary to further enhance our comprehension of the impact of exposure to EO on periodontal status.

Fighting age-related orthopedic diseases: focusing on ferroptosis

Ferroptosis, a unique type of cell death, is characterized by iron-dependent accumulation and lipid peroxidation. It is closely related to multiple biological processes, including iron metabolism, polyunsaturated fatty acid metabolism, and the biosynthesis of compounds with antioxidant activities, including glutathione. In the past 10 years, increasing evidence has indicated a potentially strong relationship between ferroptosis and the onset and progression of age-related orthopedic diseases, such as osteoporosis and osteoarthritis. Therefore, in-depth knowledge of the regulatory mechanisms of ferroptosis in age-related orthopedic diseases may help improve disease treatment and prevention. This review provides an overview of recent research on ferroptosis and its influences on bone and cartilage homeostasis. It begins with a brief overview of systemic iron metabolism and ferroptosis, particularly the potential mechanisms of ferroptosis. It presents a discussion on the role of ferroptosis in age-related orthopedic diseases, including promotion of bone loss and cartilage degradation and the inhibition of osteogenesis. Finally, it focuses on the future of targeting ferroptosis to treat age-related orthopedic diseases with the intention of inspiring further clinical research and the development of therapeutic strategies.

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.