Astaxanthin Inhibits Diabetes-Triggered Periodontal Destruction, Ameliorates Oxidative Complications in STZ-Injected Mice, and Recovers Nrf2-Dependent Antioxidant System

Optimized extraction, enrichment, identification and hypoglycemic effects of triterpenoid acids from Hippophae rhamnoides L pomace

The Hippophae rhamnoides L. pomace was generated in the production process for juice, wine of food industry. To expand the application of pomace, the extraction process optimization, enrichment and identification of triterpene acids were performed in this study. The extraction yield was 14.87% under optimal ultrasound-assisted extraction techniques performed via response surface methodology. The extract was subsequently purified to obtain the triterpenoid acid enrichment fraction (TPF) with the content of 75.23% ± 1.45%. 13 triterpenoid acids were identified via UPLC-Triple-TOF MS/MS and further semi-quantified through comparison with triterpenoid acid standards. TPF exhibited a strong inhibitory effect on α-glucosidase with IC50 value of 5.027 ± 0.375 μg/mL, as determined via enzyme inhibition experiment and molecular docking. Additionally, the TPF significantly reduced postprandial glucose levels, as revealed via carbohydrate tolerance tests, as well as ameliorate serum lipid profiles. Therefore, pomace may be a promising resource of functional food components with therapeutic and commercial values.

Nocardamine mitigates cellular dysfunction induced by oxidative stress in periodontal ligament stem cells

BACKGROUND

The role of periodontal ligament stem cells (PDLSCs) in repairing periodontal destruction is crucial, but their functions can be impaired by excessive oxidative stress (OS). Nocardamine (NOCA), a cyclic siderophore, has been shown to possess anti-cancer and anti-bacterial properties. This study aimed to investigate the protective mechanisms of NOCA against OS-induced cellular dysfunction in PDLSCs.

METHODS

The cytotoxicity of NOCA on PDLSCs was assessed using a CCK-8 assay. PDLSCs were then treated with hydrogen peroxide (H2O2) to induce OS. ROS levels, cell viability, and antioxidant factor expression were analyzed using relevant kits after treatment. Small molecule inhibitors U0126 and XAV-939 were employed to block ERK signaling and Wnt pathways respectively. Osteogenic differentiation was assessed using alkaline phosphatase (ALP) activity staining and Alizarin Red S (ARS) staining of mineralized nodules. Expression levels of osteogenic gene markers and ERK pathway were determined via real-time quantitative polymerase chain reaction (RT-qPCR) or western blot (WB) analysis. β-catenin nuclear localization was examined by western blotting and confocal microscopy.

RESULTS

NOCA exhibited no significant cytotoxicity at concentrations below 20 µM and effectively inhibited H2O2-induced OS in PDLSCs. NOCA also restored ALP activity, mineralized nodule formation, and the expression of osteogenic markers in H2O2-stimulated PDLSCs. Mechanistically, NOCA increased p-ERK level and promoted β-catenin translocation into the nucleus; however, blocking ERK pathway disrupted the osteogenic protection provided by NOCA and impaired its ability to induce β-catenin nuclear translocation under OS conditions in PDLSCs.

CONCLUSIONS

NOCA protected PDLSCs against H2O2-induced OS and effectively restored impaired osteogenic differentiation in PDLSCs by modulating the ERK/Wnt signaling pathway.

Astaxanthin Supplementation as a Potential Strategy for Enhancing Mitochondrial Adaptations in the Endurance Athlete: An Invited Review

Astaxanthin, a potent antioxidant found in marine organisms such as microalgae and krill, may offer ergogenic benefits to endurance athletes. Originally used in fish feed, astaxanthin has shown a greater ability to mitigate various reactive oxygen species and maintain the structural integrity of mitochondria compared to other exogenous antioxidants. More recent work has shown that astaxanthin may improve: (1) cycling time trial performance, (2) cardiorespiratory measures such as submaximal heart rate during running or cycling, (3) recovery from delayed-onset muscle soreness, and (4) endogenous antioxidant capacity such as whole blood glutathione within trained populations. In this review, the history of astaxanthin and its chemical structure are first outlined before briefly describing the various adaptations (e.g., mitochondrial biogenesis, enhanced endogenous antioxidant capacity, etc.) which take place specifically at the mitochondrial level as a result of chronic endurance training. The review then concludes with the potential additive effects that astaxanthin may offer in conjunction with endurance training for the endurance athlete and offers some suggested practical recommendations for athletes and coaches interested in supplementing with astaxanthin.

FNDC5/irisin ameliorates bone loss of type 1 diabetes by suppressing endoplasmic reticulum stress‑mediated ferroptosis

BACKGROUND

Ferroptosis is known to play a crucial role in diabetic osteopathy. However, key genes and molecular mechanisms remain largely unclear. This study aimed to identify a crucial ferroptosis-related differentially expressed gene (FR-DEG) in diabetic osteopathy and investigate its potential mechanism.

METHODS

We identified fibronectin type III domain-containing protein 5 (FNDC5)/irisin as an essential FR-DEG in diabetic osteopathy using the Ferroptosis Database (FerrDb) and GSE189112 dataset. Initially, a diabetic mouse model was induced by intraperitoneal injection of streptozotocin (STZ), followed by intraperitoneal injection of irisin. MC3T3-E1 cells treated with high glucose (HG) were used as an in vitro model. FNDC5 overexpression plasmid was used to explore underlying mechanisms in vitro experiments. Femurs were collected for micro-CT scan, histomorphometry, and immunohistochemical analysis. Peripheral serum was collected for ELISA analysis. Cell viability was assessed using a CCK-8 kit. The levels of glutathione (GSH), malondialdehyde (MDA), iron, reactive oxygen species (ROS), and lipid ROS were detected by the corresponding kits. Mitochondria ultrastructure was observed through transmission electron microscopy (TEM). Finally, mRNA and protein expressions were examined by quantitative real-time PCR (qRT-PCR) and western blot analysis.

RESULTS

The expression of FNDC5 was found to be significantly decreased in both in vivo and in vitro models. Treatment with irisin significantly suppressed ferroptosis and improved bone loss. This was demonstrated by reduced lipid peroxidation and iron overload, increased antioxidant capability, as well as the inhibition of the ferroptosis pathway in bone tissues. Furthermore, in vitro studies demonstrated that FNDC5 overexpression significantly improved HG-induced ferroptosis and promoted osteogenesis. Mechanistic investigations revealed that FNDC5 overexpression mitigated ferroptosis in osteoblasts by inhibiting the eukaryotic initiation factor 2 alpha (eIF2α)/activated transcription factor 4 (ATF4)/C/EBP-homologous protein (CHOP) pathway.

CONCLUSIONS

Collectively, our study uncovered the important role of FNDC5/irisin in regulating ferroptosis of diabetic osteopathy, which might be a potential therapeutic target.

Clostridium butyricum MIYAIRI 588 alleviates periodontal bone loss in mice with diabetes mellitus

The gut microbiota is a bridge linking periodontitis and systemic diseases, such as diabetes mellitus (DM). The probiotic Clostridium butyricum MIYAIRI 588 (CBM588) is reportedly an effective therapeutic approach for gut dysbiosis. Here, in a mouse model, we explored the therapeutic effect of CBM588 on periodontal bone destruction in DM and DM-associated periodontitis (DMP), as well as the underlying mechanism. Micro-computed tomography revealed that DM and DMP both aggravated periodontal bone destruction, which was alleviated by intragastric supplementation with CBM588. Moreover, 16S rRNA sequencing and untargeted metabolite analysis indicated that CBM588 ameliorated DMP-triggered dysbiosis and led to reduced oxidative stress associated with elevated 4-hydroxybenzenemethanol (4-HBA) in serum. Furthermore, in vitro and in vivo experiments found that the metabolite 4-HBA promoted nuclear factor erythroid 2-related factor 2 (Nrf2) signaling activation and modulated the polarization of macrophages, thus ameliorating inflammatory bone destruction in DMP. Our study demonstrates the protective effects of CBM588 in DM-induced mice, with and without ligature-induced periodontitis. The mechanism involves regulation of the gut microbiota and restoration of the integrity of the gut barrier to alleviate oxidative damage by elevating serum 4-HBA. This study suggests the possibility of CBM588 as a therapeutic adjuvant for periodontal treatment in diabetes patients.

A Narrative Review: The Effect and Importance of Carotenoids on Aging and Aging-Related Diseases

Aging is generally defined as a time-dependent functional decline that affects most living organisms. The positive increase in life expectancy has brought along aging-related diseases. Oxidative stress caused by the imbalance between pro-oxidants and antioxidants can be given as one of the causes of aging. At the same time, the increase in oxidative stress and reactive oxygen species (ROS) is main reason for the increase in aging-related diseases such as cardiovascular, neurodegenerative, liver, skin, and eye diseases and diabetes. Carotenoids, a natural compound, can be used to change the course of aging and aging-related diseases, thanks to their highly effective oxygen-quenching and ROS-scavenging properties. Therefore, in this narrative review, conducted using the PubMed, ScienceDirect, and Google Scholar databases and complying with the Scale for the Assessment of Narrative Review Articles (SANRA) guidelines, the effects of carotenoids on aging and aging-related diseases were analyzed. Carotenoids are fat-soluble, highly unsaturated pigments that occur naturally in plants, fungi, algae, and photosynthetic bacteria. A large number of works have been conducted on carotenoids in relation to aging and aging-related diseases. Animal and human studies have found that carotenoids can significantly reduce obesity and fatty liver, lower blood sugar, and improve liver fibrosis in cirrhosis, as well as reduce the risk of cardiovascular disease and erythema formation, while also lowering glycated hemoglobin and fasting plasma glucose levels. Carotenoid supplementation may be effective in preventing and delaying aging and aging-related diseases, preventing and treating eye fatigue and dry eye disease, and improving macular function. These pigments can be used to stop, delay, or treat aging-related diseases due to their powerful antioxidant, restorative, anti-proliferative, anti-inflammatory, and anti-aging properties. As an increasingly aging population emerges globally, this review could provide an important prospective contribution to public health.

Resveratrol Alleviates Diabetic Periodontitis-Induced Alveolar Osteocyte Ferroptosis Possibly via Regulation of SLC7A11/GPX4

The mode and mechanism of diabetic periodontitis-induced alveolar-osteocyte death are still unclear. This study aimed to investigate the occurrence of ferroptosis in alveolar osteocytes during diabetic periodontitis and the therapeutic potential of resveratrol to alleviate osteocyte ferroptosis. Diabetic periodontitis was induced in C57/BL6-male mice and treated with or without resveratrol. Periodontitis pathogenicity was analyzed by micro-CT and histology, and alveolar-osteocyte ferroptosis was analyzed by immunohistochemistry. MLOY4 osteocytes were treated with P. gingivalis-derived lipopolysaccharide (LPS)+advanced glycosylated end products (AGEs) mimicking diabetic periodontitis condition in vitro, with or without resveratrol or ferrostatin-1 (ferroptosis inhibitor). Osteocyte ferroptosis and expression of inflammatory mediators were analyzed. Diabetic periodontitis aggravated periodontitis pathogenicity and inhibited the expression of GPX4 and SLC7A11 in alveolar osteocytes and resveratrol alleviated these effects. LPS+AGEs triggered osteocyte ferroptosis in vitro as indicated by the downregulated GPX4 and SLC7A11, upregulated malondialdehyde, disrupted mitochondrial morphology, and overexpressed pro-inflammatory mediators IL-1β, TNF-α, SOST, RANKL, and IL-6, and ferrostatin-1 or resveratrol treatment reversed these effects. LPS+AGEs upregulated pIKBα and pNF-κB p65 expression in osteocytes, and resveratrol or ferrostatin-1 reversed this effect. In conclusion, diabetic periodontitis triggers alveolar osteocyte ferroptosis possibly via disruption of the SLC7A11/GPX4 axis, and resveratrol has therapeutic potential to correct this biological event.

Astaxanthin Protects against Hyperglycemia-Induced Oxidative and Inflammatory Damage to Bone Marrow and to Bone Marrow-Retained Stem Cells and Restores Normal Hematopoiesis in Streptozotocin-Induced Diabetic Mice

Hyperglycemia has various adverse health effects, some of which are due to chronic oxidative and inflammatory impairment of bone marrow (BM), hematopoietic stem cells (HSCs), and mesenchymal stem cells (MSCs). Astaxanthin (ASTX) has been shown to ameliorate hyperglycemia-associated systemic complications and acute mortality, and this effect is partially associated with restoration of normal hematopoiesis. Here, the effects of ASTX on diabetes-induced complications in BM and BM stem cells were investigated, and the underlying molecular mechanisms were elucidated. Ten-week-old C57BL/6 mice received a single intraperitoneal injection of streptozotocin (STZ; 150 mg/kg) in combination with oral gavage of ASTX (12.5 mg/kg) for 30 or 60 consecutive days. Supplemental ASTX ameliorated acute mortality and restored the STZ-impaired bone mass accrual and BM microenvironment in STZ-injected mice. Oral gavage of ASTX suppressed osteoclast formation in the BM of STZ-injected mice. Specifically, supplementation with ASTX inhibited oxidative stress and senescence induction of BM HSCs and MSCs and ameliorated hematopoietic disorders in STZ-injected mice. These effects of ASTX were associated with BM restoration of angiopoietin 1, stromal cell-derived factor 1, β-catenin, and Nrf2. Long-term ASTX gavage also recovered the STZ-induced dysfunction in migration, colony formation, and mineralization of BM-derived stromal cells. Further, a direct addition of ASTX exhibited direct and dose-dependent inhibition of osteoclastic activation without cytotoxic effects. Collectively, these results indicate that ASTX protects against diabetes-induced damage in the BM microenvironment in BM, HSCs, and MSCs and restores normal hematopoiesis and bone accrual in STZ-injected mice.

Single-Cell Transcriptomic Atlas of Gingival Mucosa in Type 2 Diabetes

The oral gingival barrier is a constantly stimulated and dynamic environment where homeostasis is often disrupted, resulting in inflammatory periodontal diseases. Type 2 diabetes (T2D) has been reported to be associated with gingival barrier dysfunction, but the effect and underlying mechanism are inconclusive. Herein, we performed single-cell RNA sequencing (scRNA-seq) of gingiva from leptin receptor-deficient mice (db/db) to examine the gingival heterogeneity in the context of T2D. Periodontal health of control mice is characterized by populations of Krt14⁺-expressing epithelial cells and Col1a1⁺-fibroblasts mediating immune homeostasis primarily through the enrichment of innate lymphoid cells. The db/db gingiva exhibited decreased epithelial/stromal ratio and dysfunctional barrier. We further observed stromal, particularly fibroblast immune hyperresponsiveness, linked to the recruitment of myeloid-derived cells at the db/db gingiva. Both scRNA-seq and histological analysis suggested the inflammatory signaling between fibroblasts and neutrophils as a potential driver of diabetes-induced periodontal damage. Notably, the "immune-like" stromal cells were wired toward the induction of gingival γδ T hyperresponsiveness in db/db mice. Our work reveals that the "immune-like" fibroblasts with transcriptional diversity are involved in the innate immune homeostasis at the diabetic gingiva. It highlights a potentially significant role of these cell types in its pathogenesis.

Diabetic oxidative stress-induced telomere damage aggravates periodontal bone loss in periodontitis

Periodontitis, one of the most common oral complications of diabetes mellitus (DM), causes a reduction in alveolar bone height and loss of alveolar bone mass. It has been shown that DM aggravates the progression of periodontitis, but the mechanism remains inconclusive. The hyperglycemic environment of DM has been proven to generate reactive oxygen species (ROS). Since telomeres, guanine-rich repeats, are highly susceptible to oxidative attack, we speculate that the excessive accumulation of ROS in DM could induce telomere damage resulting in dysfunction of periodontal ligament cells, especially periodontal ligament stem cells (PDLSCs), which reduces the ability of tissue repair and reconstruction in diabetic periodontitis. In this study, our current data revealed that oxidative telomere damage occurred in the periodontal ligaments of diabetic mice. And Micro-CT scans showed reduced alveolar bone height and impaired alveolar bone mass in a diabetic periodontitis model. Next, cultured mouse PDLSCs (mPDLSCs) were treated with the oxidant tert-butyl hydroperoxide (t-BHP) in vitro, as we expected telomere damage was observed and resulted in cellular senescence and dysfunction. Taken together, oxidative stress in DM causes telomere dysfunction and PDLSCs senescence, which influences periodontal bone tissue regeneration and reconstruction and ultimately exacerbates bone loss in periodontitis.

Pathogenic Molecular Mechanisms in Periodontitis and Peri-Implantitis: Role of Advanced Glycation End Products

Advanced Glycation End Products (AGEs), the products of the non-enzymatic oxidation of proteins, nucleic acids, and lipids, are accumulated in periodontal tissues under hyperglycemic conditions such as Diabetes Mellitus (DM) and are responsible for sustained periodontal destruction. AGEs mediate their intracellular effects either directly or indirectly through receptor binding (via RAGE) in all types of periodontal ligament cells (osteocytes, gingival fibroblasts, stem cells, epithelial cells), indicating an important target for intervention. In combination with lipopolysaccharides (LPS) from Porphyromonas gingivalis (Pg), the negative impact of AGEs on periodontal tissue is further enhanced and accentuated. In addition, AGE accumulation is evident in peri-implantitis, yet through different underlying molecular mechanisms. Novel therapeutic approaches targeting the effects of AGEs in periodontal ligament cells show beneficial effects in pre-clinical studies. Herein, we provide evidence on the detrimental role of AGE accumulation in oral cavity tissues and their associated signaling pathways in periodontitis and peri-implantitis to further highlight the significance of oral or topical use of AGE blockers or inhibitors along with dental biofilms’ removal and DM regulation in patients’ management.

Astaxanthin as a Novel Mitochondrial Regulator: A New Aspect of Carotenoids, beyond Antioxidants

Astaxanthin is a member of the carotenoid family that is found abundantly in marine organisms, and has been gaining attention in recent years due to its varied biological/physiological activities. It has been reported that astaxanthin functions both as a pigment, and as an antioxidant with superior free radical quenching capacity. We recently reported that astaxanthin modulated mitochondrial functions by a novel mechanism independent of its antioxidant function. In this paper, we review astaxanthin’s well-known antioxidant activity, and expand on astaxanthin’s lesser-known molecular targets, and its role in mitochondrial energy metabolism.