Oxidative Stress Inhibits Endotoxin Tolerance and May Affect Periodontitis

Rescuing fertility: Itaconic acid prevents ovarian damage through NRF2-mediated pyroptosis pathways in diminished ovarian reserve models

BACKGROUND

Diminished ovarian reserve (DOR) is a major cause of infertility, often triggered by inflammation and oxidative stress. Pyroptosis, a form of programmed cell death, has been implicated in DOR pathogenesis. Itaconic acid (IA), an endogenous metabolite, is known for its anti-inflammatory and antioxidant properties. This study aimed to explore whether IA could alleviate lipopolysaccharide (LPS)-induced DOR in mice by inhibiting pyroptosis through the NRF2 pathway.

METHODS

A DOR mouse model was established by administering LPS for 5 consecutive days, followed by IA treatment. Ovarian function was assessed by follicle count and hormone levels. Inflammatory markers, oxidative stress, and pyroptosis-related proteins were evaluated in both in vivo and in vitro models. The molecular mechanism was further investigated using inhibitors and molecular docking studies.

RESULTS

IA significantly improved ovarian function in LPS-induced DOR mice by increasing the number of follicles and normalizing hormone levels. IA also reduced inflammation, oxidative stress, and pyroptosis, as evidenced by lower expression of NLRP3, cleaved-caspase-1, and N-GSDMD, while increasing NRF2 expression. In vitro, IA enhanced granulosa cell (GC) viability, reduced reactive oxygen species (ROS), and decreased pyroptosis in LPS-treated GCs. Additionally, the beneficial effects of IA were mediated via the NRF2 pathway, as NRF2 inhibition (ML385) reversed these improvements. Additionally, we identified GSDMD as a downstream target of IA, with inhibition of GSDMD ameliorating DOR progression and inflammatory responses.

CONCLUSION

IA alleviates LPS-induced DOR by reducing inflammation, oxidative stress, and pyroptosis through activation of the NRF2 signaling and direct inhibition of the GSDMD pathway. These findings suggest that IA may serve as a potential therapeutic agent for improving ovarian reserve and fertility.

Identification and Validation of Ferritinophagy-Related Biomarkers in Periodontitis

OBJECTIVE

While ferritinophagy is believed to play a significant role in the development of periodontitis, the exact mechanisms remain unclear. This study aimed to investigate the biomarkers associated with ferritinophagy in periodontitis using transcriptomic data.

METHODS

Two periodontitis-related datasets from Gene Expression Omnibus, GSE10334, and GSE16134, served as the training and validation cohorts, respectively. Additionally, 36 ferritinophagy-related genes (FRGs) were obtained from the GeneCards database. We compared the expression differences of FRGs between the periodontitis and control groups, identifying the different FRGs as candidates. Weighted gene coexpression network analysis (WGCNA) was applied to capture the key modules and modular genes related to periodontitis, utilizing the candidate FRG scores as trait. Then we intersected these with key module genes to identify differentially expressed FRGs. Hub genes were filtered using a protein-protein interaction network. Ultimately, biomarkers were acquired through machine learning, receiver operating characteristic curves, and expression levels. In addition, biomarker-associated immune cells and functional pathways were analysed to predict the upstream regulatory molecules.

RESULTS

In total, 18 candidate FRGs showed significant differences between the periodontitis and control groups, and from the protein-protein interaction network, eight hub genes were identified among the 175 differentially expressed FRGs by analysing 1096 differentially expressed genes and 4479 key modular genes. Eventually, ALDH2, diazepam binding inhibitor, HMGCR, OXCT1, and ACAT2 were identified as potential biomarkers through machine learning algorithms, receiver operating characteristic curve analysis, and gene expression assessments. In addition, resting dendritic cells, mast cells, and follicular helper T cells were positively correlated with the five biomarkers (Cor > 0.3 and P < .05). All five biomarkers are involved in the translation initiation pathway, including transcription factors like KLF5 and microRNAs such as hsa-miR-495-3p and hsa-miR-27a-3p. Reverse transcription-quantitative polymerase chain reaction analysis showed that all biomarkers were expressed at low levels in the periodontitis group. However, the differences in expression levels for OXCT1 and ACAT2 between groups were not statistically significant.

CONCLUSIONS

A total of five ferritinophagy-related biomarkers - ALDH2, diazepam binding inhibitor, HMGCR, OXCT1, and ACAT2 - were screened to explore new treatment options for periodontitis.

Extracellular Vesicles From LPS-Treated PDLSCs Induce NLRP3 Inflammasome Activation in Periodontitis

OBJECTIVE

This study aimed to investigate the effects of lipopolysaccharide (LPS)-pretreated primary periodontal ligament stem cell (PDLSC)-derived extracellular vesicles (EVs) (L-PDLSC-EVs) on periodontitis.

MATERIALS AND METHODS

PDLSCs were obtained from mouse periodontal ligaments via enzymatic digestion. An in vitro inflammatory microenvironment for PDLSCs was established using LPS, and L-PDLSC-EVs were isolated through ultracentrifugation and identified. EVs from different treatments were co-incubated with RAW264.7 macrophages (Mφs) or periodontal ligament fibroblasts (PLFs) and their co-cultures, whereafter the biological behaviors in Mφs and PLFs were evaluated. Periodontitis mouse models were established to verify the role of L-PDLSC-EVs and the mechanisms involved.

RESULTS

There were no significant changes in the characteristics of L-PDLSC-EVs compared with control EVs. L-PDLSC-EVs promoted M1-type Mφ polarization and activated the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome. Furthermore, L-PDLSC-EVs promoted PLF cytotoxicity and apoptosis by enhancing the M1 polarization of Mφs. In periodontitis mouse models, L-PDLSC-EVs facilitated alveolar bone loss, PLF injury, and inflammatory responses, accompanied by an increased proportion of M1-type Mφs and reinforced NLRP3 inflammasome activation.

CONCLUSIONS

L-PDLSC-EVs promoted PLF injury and exacerbated periodontitis through activating the NLRP3 inflammasome and promoting the polarization of M1-type Mφs, providing novel insights for the periodontitis progression.

Role of Pink1 in Regulating Osteoclast Differentiation during Periodontitis

Periodontitis has recently been recognized as an inflammatory disease caused by oxidative stress, with mitochondrial dysfunction being a key factor leading to oxidative stress. PTEN-induced kinase 1 (PINK1) is an essential protein for mitochondrial quality control, which protects cells from oxidative stress by inducing mitophagy to degrade damaged mitochondria, but its role in periodontitis has not been elucidated. This study aimed to explore the contribution and underlying mechanisms of Pink1 in regulating the differentiation and function of osteoclasts during periodontitis. Here we observed a significant downregulation of PINK1 expression in periodontitis-affected tissues. Then we constructed a periodontitis model in mice with fluorescently labeled mononuclear/macrophages, and the results showed that as the modeling time extended, the alveolar bone destruction gradually worsened and was accompanied by gradually decreased Pink1 expression in osteoclasts and a significantly increased osteoclast number. In vitro experiments further demonstrated a negative correlation between Pink1 and osteoclast differentiation. In addition, alveolar bone destruction in the Pink1 knockout mice was significantly more advanced than that in the littermate wild type mice after ligature-induced periodontitis and enhanced osteoclastogenesis and bone-resorptive capacity in vitro. RNA-sequencing analysis and in vitro validation revealed that the absence of Pink1 led to a decrease in oxidative phosphorylation levels and an enhancement of calcium-mediated signaling, specifically the calcineurin-NFATc1 pathway, via an intracellular calcium source. Further mechanistic studies found that the deficiency of Pink1 inhibited mitophagy but strengthened mitochondrial-endoplasmic reticulum coupling, which, by promoting the interaction of Mfn2-IP3R-VDAC1 proteins, increased the concentration of mitochondrial calcium ions, thereby triggering more active osteoclast differentiation. The aforementioned process can be reversed by the IP3R channel inhibitor Bcl-XL. These findings unveiled that Pink1 was involved in osteoclast differentiation by regulating mitochondrial calcium transport mediated by mitochondria-associated endoplasmic reticulum membranes, providing a new theoretical basis for the pathogenesis and treatment of periodontitis.

Long intergenic non-coding RNA 01126 activates IL-6/JAK2/STAT3 pathway to promote periodontitis pathogenesis

OBJECTIVES

Periodontitis seriously affects oral-related quality of life and overall health. Long intergenic non-coding RNA 01126 (LINC01126) is aberrantly expressed in periodontitis tissues. This study aimed to explore the possible pathogenesis of LINC01126 in periodontitis.

METHODS

Inflammatory model of human gingival fibroblasts (HGFs) was established. Cell Counting Kit-8 (CCK-8), wound healing assay, and flow cytometry were utilized to detect biological roles of LINC01126. Binding site of miR-655-3p to LINC01126 and IL-6 was predicted. Then, subcellular localization of LINC01126 and the binding ability of miR-655-3p to LINC01126 and IL-6 in HGFs were verified. Hematoxylin-Eosin (H&E) staining and immunohistochemistry (IHC) staining were utilized to detect tissue morphology and proteins expression of clinical samples.

RESULTS

LINC01126 silencing can alleviate cell inflammation induced by lipopolysaccharide derived from Porphyromonas gingivalis, reduce cell apoptosis, and promote cell migration. As a "sponge" for miR-655-3p, LINC01126 inhibits its binding to mRNA of IL-6, thereby promoting inflammation progression and JAK2/STAT3 pathway activation. Quantitative real-time PCR, Western Blot, and IHC results of clinical tissue samples further confirmed that miR-655-3p expression was down-regulated and IL-6/JAK2/STAT3 was abnormally activated in periodontitis tissues.

CONCLUSIONS

In summary, serving as an endogenous competitive RNA of miR-655-3p, LINC01126 promotes IL-6/JAK2/STAT3 pathway activation, thereby promoting periodontitis pathogenesis.

TRPV1 Regulates Proinflammatory Properties of M1 Macrophages in Periodontitis Via NRF2

Periodontitis, characterized by progressive alveolar bone destruction, leads to the loss of attachment and stability of the affected teeth. Macrophages, especially the proinflammatory M1 subtype, are key in periodontitis pathogenesis, driving the disease's inflammatory and destructive processes. Despite existing insight into their involvement, comprehensive understanding of the underlying molecular mechanisms remains limited. TRPV1 is a non-selective cation channel protein and is known to regulate cellular function and homeostasis in macrophages. Our research objective was to investigate the impact of TRPV1 on the proinflammatory attributes of M1 macrophages in periodontal tissues, exploring potential mechanistic pathways. A mouse model of periodontitis was established using Porphyromonas gingivalis inoculation and ligature application around the maxillary second molar. Immunohistological analysis showed a significant reduction in macrophage TRPV1 expression in periodontitis-induced mice. Treatment with capsaicin, a TRPV1 agonist, was observed to effectively elevate TRPV1 expression in these macrophages. Furthermore, micro-computed tomography analysis revealed a marked decrease in alveolar bone resorption in the capsaicin -treated group, compared with vehicle and healthy control groups. Our in vitro findings show that capsaicin treatment successfully attenuated LPS-induced TNF-α and IL-6 production in macrophages, mediated through NRF2 activation, consequently reducing intracellular ROS levels. These findings suggest that TRPV1 agonists, through modulating M1 macrophage activity and up-regulating TRPV1, could be a novel therapeutic approach in periodontal disease management.

Rapamycin Attenuates H2O2-Induced Oxidative Stress-Related Senescence in Human Skin Fibroblasts

BACKGROUND

Oxidative stress plays an important role in the skin aging process. Rapamycin has been shown to have anti-aging effects, but its role in oxidative senescence of skin cells remains unclear. The aim of this study was to explore the effect of rapamycin on oxidative stress-induced skin cell senescence and to illustrate the mechanism.

METHODS

Primary human skin fibroblasts (HSFs) were extracted and a model of H2O2-induced oxidative senescence was constructed, and the effects of rapamycin on their value-added and migratory capacities were detected by CCK-8 and scratch assays. SA-β-gal was utilized to detect senescence, oxidatively closely related factors were also assessed. Gene and protein expressions of senescence, oxidative, and autophagy were detected by western blotting and quantitative-PCR. The data were analyzed by one-way analysis of variance.

RESULTS

Rapamycin (0.1 nmol/L for 48 h) promoted the proliferative and migration of H2O2-treated HSFs (p < 0.05), decreased senescent phenotypes SA-β-gal staining and the expression of P53, and MMP-1 proteins, and increased the expression level of COL1A-1 (p < 0.001). Rapamycin also enhanced the activities of SOD and HO-1, and effectively removed intracellular ROS, MDA levels (p < 0.05), in addition, autophagy-related proteins and genes were significantly elevated after rapamycin pretreatment (p < 0.001). Rapamycin upregulated the autophagy pathway to exert its protective effects.

CONCLUSION

Our findings indicate that rapamycin shields HSFs from H2O2-induced oxidative damage, the mechanism is related to the reduction of intracellular peroxidation and upregulation of autophagy pathway. Therefore, rapamycin has the potential to be useful in the investigation and prevention of signs of aging and oxidative stress.

Potential mechanisms and therapeutic strategies for LPS-associated female fertility decline

As a major component of the outer membrane of Gram-negative bacteria, lipopolysaccharide (LPS) can be recognized by toll-like receptors (TLRs) and induce inflammation through MyD88 or the TIR domain-containing adapter-inducing interferon-β (TRIF) pathway. Previous studies have found that LPS-associated inflammatory/immune challenges were associated with ovarian dysfunction and reduced female fertility. However, the etiology and pathogenesis of female fertility decline associated with LPS are currently complex and multifaceted. In this review, PubMed was used to search for references on LPS and fertility decline so as to elucidate the potential mechanisms of LPS-associated female fertility decline and summarize therapeutic strategies that may improve LPS-associated fertility decline.

Puerarin Delays Mammary Gland Aging by Regulating Gut Microbiota and Inhibiting the p38MAPK Signaling Pathway

Mammary gland aging is one of the most important problems faced by humans and animals. How to delay mammary gland aging is particularly important. Puerarin is a kind of isoflavone substance extracted from Pueraria lobata, which has anti-inflammatory, antioxidant, and other pharmacological effects. However, the role of puerarin in delaying lipopolysaccharide (LPS)-induced mammary gland aging and its underlying mechanism remains unclear. On the one hand, we found that puerarin could significantly downregulate the expression of senescence-associated secretory phenotype (SASP) and age-related indicators (SA-β-gal, p53, p21, p16) in mammary glands of mice. In addition, puerarin mainly inhibited the p38MAPK signaling pathway to repair mitochondrial damage and delay mammary gland aging. On the other hand, puerarin could also delay the cellular senescence of mice mammary epithelial cells (mMECs) by targeting gut microbiota and promoting the secretion of gut microbiota metabolites. In conclusion, puerarin could not only directly act on the mMECs but also regulate the gut microbiota, thus, playing a role in delaying the aging of the mammary gland. Based on the above findings, we have discovered a new pathway for puerarin to delay mammary gland aging.

Association between biological aging and periodontitis using NHANES 2009-2014 and mendelian randomization

Aging is a recognized risk factor for periodontitis, while biological aging could provide more accurate insights into an individual's functional status. This study aimed to investigate the potential association between biological aging and periodontitis. Epidemiological data from 9803 participants in the 2009-2014 National Health and Nutrition Examination Survey were analyzed at a cross-sectional level to assess this link. Three biological ages [Klemera-Doubal method (KDM), PhenoAge, and homeostatic dysregulation (HD)] and two measures of accelerated biological aging (BioAgeAccel and PhenoAgeAccel) were set as primary exposure and were calculated. Logistic regression and restricted cubic spline regression were employed to examine the relationship between biological aging and periodontitis. Additionally, Mendelian randomization analysis was conducted to explore the causal connection between accelerated biological aging and periodontitis. After adjusting for age, gender, race, educational level, marital status, ratio of family income, and disease conditions, this study, found a significant association between subjects with older higher biological ages, accelerated biological aging, and periodontitis. Specifically, for a per year increase in the three biological ages (HD, KDM, and PhenoAge), the risk of periodontitis increases by 15%, 3%, and 4% respectively. Individuals who had positive BioAgeAccel or PhenoAgeAccel were 20% or 37% more likely to develop periodontitis compared with those who had negative BioAgeAccel or PhenoAgeAccel. Furthermore, a significant non-linear positive relationship was observed between the three biological ages, accelerated biological aging, and periodontitis. However, the Mendelian randomization analysis indicated no causal effect of accelerated biological aging on periodontitis. Our findings suggest that biological aging may contribute to the risk of periodontitis, highlighting the potential utility of preventive strategies targeting aging-related pathways in reducing periodontitis risk among older adults.

Multifunctional Metal-Phenolic Composites Promote Efficient Periodontitis Treatment via Antibacterial and Osteogenic Properties

Periodontitis, a complex inflammatory disease initiated by bacterial infections, presents a significant challenge in public health. The increased levels of reactive oxygen species and the subsequent exaggerated immune response associated with periodontitis often lead to alveolar bone resorption and tooth loss. Herein, we develop multifunctional metal-phenolic composites (i.e., Au@MPN-BMP2) to address the complex nature of periodontitis, where gold nanoparticles (AuNPs) are coated by metal-phenolic networks (MPNs) and bone morphogenetic protein 2 (BMP2). In this design, MPNs exhibit remarkable antibacterial and antioxidant properties, and AuNPs and BMP2 promote osteogenic differentiation of bone marrow mesenchymal stem cells under inflammatory conditions. In a rat model of periodontitis, treatment with Au@MPN-BMP2 leads to notable therapeutic outcomes, including mitigated oxidative stress, reduced progression of inflammation, and the significant prevention of inflammatory bone loss. These results highlight the multifunctionality of Au@MPN-BMP2 nanoparticles as a promising therapeutic approach for periodontitis, addressing both microbial causative factors and an overactivated immune response. We envision that the rational design of metal-phenolic composites will provide versatile nanoplatforms for tissue regeneration and potential clinical applications.

Mitochondria: An Emerging Unavoidable Link in the Pathogenesis of Periodontitis Caused by Porphyromonas gingivalis

Porphyromonas gingivalis (P. gingivalis) is a key pathogen of periodontitis. Increasing evidence shows that P. gingivalis signals to mitochondria in periodontal cells, including gingival epithelial cells, gingival fibroblast cells, immune cells, etc. Mitochondrial dysfunction affects the cellular state and participates in periodontal inflammatory response through the aberrant release of mitochondrial contents. In the current review, it was summarized that P. gingivalis induced mitochondrial dysfunction by altering the mitochondrial metabolic state, unbalancing mitochondrial quality control, prompting mitochondrial reactive oxygen species (ROS) production, and regulating mitochondria-mediated apoptosis. This review outlines the impacts of P. gingivalis and its virulence factors on the mitochondrial function of periodontal cells and their role in periodontitis.