Luteolin and apigenin activate the Oct-4/Sox2 signal via NFATc1 in human periodontal ligament cells

Cellular Senescence in Craniofacial Tissue Regeneration: Inducers, Biomarkers, and Interventions

Craniofacial defects and dental tissue loss have significant negative impacts on the structure and function of jaws and face, often resulting in psychological issues in patients, emphasizing the urgent need for effective craniofacial tissue reconstruction. Unfortunately, natural regeneration of these tissues is limited. Dental-derived mesenchymal stem cells (MSCs) have emerged as a promising resource for tissue engineering-based therapeutic approaches. However, the clinical outcomes of MSC-based transplantation have not met expectations due to various complex reasons, and cellular senescence is recognized as one of the potential mechanisms contributing to the suboptimal results. The quality of MSC decreases during large-scale in vitro expansion, and it is also influenced by the age and the health status of donors. To address these challenges, extensive efforts have been made to developing strategies to combat senescence in tissue engineering, leveraging on current knowledge of underlying mechanisms. This review aims to elucidate the impact of cell senescence in craniofacial and dental regeneration and provides an overview of state-of-the-art antisenescence strategies. We first discuss the potential factors that trigger cell senescence in craniofacial tissue engineering. Then we describe senescence biomarkers, monitoring methods for senescent MSCs, and their underlying molecular mechanisms. The primary focus of this review is on current strategies to inhibit and alleviate cell senescence in tissue engineering. We summarize the strategies concerning the prevention of cell senescence, senolysis, modulation of the senescent associated secretory phenotype, and reversal of senescent MSCs, offering promising opportunities to overcome the challenges associated with cell senescence in craniofacial tissue engineering.

Nuclear factor of activated T-cells (NFAT) regulation of IL-1β-induced retinal vascular inflammation

Chronic low-grade retinal inflammation is an essential contributor to the pathogenesis of diabetic retinopathy (DR). It is characterized by increased retinal cell expression and secretion of a variety of inflammatory cytokines; among these, IL-1β has the reputation of being a major driver of cytokine-induced inflammation. IL-1β and other cytokines drive inflammatory changes that cause damage to retinal cells, leading to the hallmark vascular lesions of DR; these include increased leukocyte adherence, vascular permeability, and capillary cell death. Nuclear factor of activated T-cells (NFAT) is a transcriptional regulator of inflammatory cytokines and adhesion molecules and is expressed in retinal cells. Consequently, it may influence multiple pathogenic steps early in DR. We investigated the NFAT-dependency of IL-1β-induced inflammation in human Müller cells (hMC) and human retinal microvascular endothelial cells (hRMEC). Our results show that an NFAT inhibitor, Inhibitor of NFAT-Calcineurin Association-6 (INCA-6), decreased IL-1β-induced expression of IL-1β and TNFα in hMC, while having no effect on VEGF, CCL2, or CCL5 expression. We also demonstrate that INCA-6 attenuated IL-1β-induced increases of IL-1β, TNFα, IL-6, CCL2, and CCL5 (inflammatory cytokines and chemokines), and ICAM-1 and E-selectin (leukocyte adhesion molecules) expression in hRMEC. INCA-6 similarly inhibited IL-1β-induced increases in leukocyte adhesion in both hRMEC monolayers in vitro and an acute model of retinal inflammation in vivo. Finally, INCA-6 rescued IL-1β-induced permeability in both hRMEC monolayers in vitro and an acute model of retinal inflammation in vivo. Taken together, these data demonstrate the potential of NFAT inhibition to mitigate retinal inflammation secondary to diabetes.

Platinum and Palladium Complexes as Promising Sources for Antitumor Treatments

There is a need for new, safer, and more effective agents to treat cancer. Cytostatics that have transition metals at their core have attracted renewed interest from scientists. Researchers are attempting to use chemotherapeutics, such as cisplatin, in combination therapy (i.e., in order to enhance their effectiveness). Moreover, studies are being carried out to modify molecules, by developing them into multinuclear structures, linking different compounds to commonly used drugs, or encapsulating them in nanoparticles to improve pharmacokinetic parameters, and increase the selectivity of these drugs. Therefore, we attempted to organize recent drug findings that contain palladium and platinum atoms in their structures.

Advances in Our Understanding of the Molecular Mechanisms of Action of Cisplatin in Cancer Therapy

Cisplatin and other platinum-based chemotherapeutic drugs have been used extensively for the treatment of human cancers such as bladder, blood, breast, cervical, esophageal, head and neck, lung, ovarian, testicular cancers, and sarcoma. Cisplatin is commonly administered intravenously as a first-line chemotherapy for patients suffering from various malignancies. Upon absorption into the cancer cell, cisplatin interacts with cellular macromolecules and exerts its cytotoxic effects through a series of biochemical mechanisms by binding to Deoxyribonucleic acid (DNA) and forming intra-strand DNA adducts leading to the inhibition of DNA synthesis and cell growth. Its primary molecular mechanism of action has been associated with the induction of both intrinsic and extrinsic pathways of apoptosis resulting from the production of reactive oxygen species through lipid peroxidation, activation of various signal transduction pathways, induction of p53 signaling and cell cycle arrest, upregulation of pro-apoptotic genes/proteins, and down-regulation of proto-oncogenes and anti-apoptotic genes/proteins. Despite great clinical outcomes, many studies have reported substantial side effects associated with cisplatin monotherapy, while others have shown substantial drug resistance in some cancer patients. Hence, new formulations and several combinational therapies with other drugs have been tested for the purpose of improving the clinical utility of cisplatin. Therefore, this review provides a comprehensive understanding of its molecular mechanisms of action in cancer therapy and discusses the therapeutic approaches to overcome cisplatin resistance and side effects.

Autophagy regulation using luteolin: new insight into its anti-tumor activity

Application of novel methods in cancer therapy is important in terms of management and treatment of the life-threatening disorder. It appears that autophagy is a potential target in cancer therapy, as a variety of drugs targeting autophagy have shown great potential in reducing the viability and proliferation of cancer cells. Autophagy is primarily a catabolic process which provides energy during starvation. Besides, this process contributes to the degradation of aged or potentially toxic components and organelles. On the other hand, the source of a variety of naturally occurring anti-tumor drugs are flavonoids which have high anti-tumor activity. Luteolin is a polyphenolic flavone with the great pharmacological effects such as anti-diabetic, hepatoprotective, antioxidant, anti-inflammation, and anti-tumor. At the present review, we demonstrate how luteolin affects on autophagy process to induce anti-tumor activity.

SOX2 is a positive regulator of osteoclast differentiation

Elucidating the mechanism underlying osteoclast differentiation is important to improve our understanding of the pathophysiologies related to skeletal diseases and osteolytic metastasis in cancer. Sex-determining region Y-box containing gene 2 (SOX2), a stemness marker, is known to affect osteoblast differentiation and cancer metastasis. However, its role in osteoclastogenesis has not been investigated to date. Here, we report that SOX2 protein and mRNA expression was upregulated during osteoclast differentiation. The overexpression or knockdown of SOX2 in osteoclast precursor cells enhanced or suppressed, respectively, receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation and migration, and nuclear factor of activated T-cell c1 (NFATc1) and factor-associated suicide ligand (FASL) expression. In addition, epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase (ERK) activation were regulated by SOX2 expression; both EGFR and ERK inhibitors abrogated the SOX2 overexpression-induced increase in osteoclast differentiation and NFATc1 expression under RANKL stimulation. Overall, these results suggest SOX2 as a positive regulatory factor during osteoclast differentiation partly through the EGFR and ERK signaling pathways, highlighting a new potential target for restoring abnormal osteoclast activation.

Influence of olive oil and its components on mesenchymal stem cell biology

Extra virgin olive oil is characterized by its high content of unsaturated fatty acid residues in triglycerides, mainly oleic acid, and the presence of bioactive and antioxidant compounds. Its consumption is associated with lower risk of suffering chronic diseases and unwanted processes linked to aging, due to the antioxidant capacity and capability of its components to modulate cellular signaling pathways. Consumption of olive oil can alter the physiology of mesenchymal stem cells (MSCs). This may explain part of the healthy effects of olive oil consumption, such as prevention of unwanted aging processes. To date, there are no specific studies on the action of olive oil on MSCs, but effects of many components of such food on cell viability and differentiation have been evaluated. The objective of this article is to review existing literature on how different compounds of extra virgin olive oil, including residues of fatty acids, vitamins, squalene, triterpenes, pigments and phenols, affect MSC maintenance and differentiation, in order to provide a better understanding of the healthy effects of this food. Interestingly, most studies have shown a positive effect of these compounds on MSCs. The collective findings support the hypothesis that at least part of the beneficial effects of extra virgin olive oil consumption on health may be mediated by its effects on MSCs.

Luteolin supports osteogenic differentiation of human periodontal ligament cells

Background

Previous research revealed that luteolin could improve the activation of alkaline phosphatase (ALP) and osteocalcin in mouse osteoblasts. We aimed to determine the effect of luteolin on osteogenic differentiation of periodontal ligament cells (PDLCs).

Methods

Cultured human PDLCs (HPDLCs) were treated by luteolin at 0.01, 0.1, 1, 10, 100 μmol/L, Wnt/β-catenin pathway inhibitor (XAV939, 5 μmol/L) alone or in combination with 1 μmol/L luteolin. Immunohistochemical staining was performed to ensure cells source. Cell activity and the ability of osteogenic differentiation in HPDLCs were determined by MTT, ALP and Alizarin Red S staining. Real-time Quantitative PCR Detecting System (qPCR) and Western blot were performed to measure the expressions of osteogenic differentiation-related genes such as bone morphogenetic protein 2 (BMP2), osteocalcin (OCN), runt-related transcription factor 2 (RUNX2), Osterix (OSX) and Wnt/β-catenin pathway proteins members cyclin D1 and β-catenin.

Results

Luteolin at concentrations of 0.01, 0.1, 1, 10, 100 μmol/L promoted cell viability, ALP activity and increased calcified nodules content in HPDLCs. The expressions of BMP2, OCN, OSX, RUNX2, β-catenin and cyclin D1 were increased by luteolin at concentrations of 0.01, 0.1, 1 μmol/L, noticeably, 1 μmol/L luteolin produced the strongest effects. In addition, XAV939 inhibited the expressions of calcification and osteogenic differentiation-related genes in HPDLCs, and 1 μmol/L luteolin availably decreased the inhibitory effect.

Conclusion

1 μmol/L luteolin accelerated osteogenic differentiation of HPDLCs via activating the Wnt/β-catenin pathway, which could be clinically applied to treat periodontal disease.

USF2 enhances the osteogenic differentiation of PDLCs by promoting ATF4 transcriptional activities

OBJECTIVE

Our study aimed to elucidate the regulatory molecules related to the osteogenic differentiation of periodontal ligament cells (PDLCs).

BACKGROUND

Periodontal ligament cells are a favorable source for cell-based therapy in periodontal bone engineering and regeneration due to their potential multilineage differentiation ability. However, the molecular mechanism and signaling pathways related to the osteogenic differentiation of PDLCs are still unclear.

METHODS

Osteoblast-specific protein expression levels were examined by ELISA in osteogenic-induced PDLCs (induced-PDLC group). A microarray assay and a bioinformatics analysis were carried out to reveal significantly expressed genes and the related pathways in induced-PDLCs, and these findings were then confirmed by qRT-PCR and a luciferase reporter assay. Finally, overexpressing and silencing gene systems were established to identify the specific transcriptional relationship and function of the target genes on the osteogenic differentiation of PDLCs.

RESULTS

Osteogenically differentiated PDLCs with high levels of osteoblast-specific proteins were established. The upstream stimulatory factor 2 (USF2) and activating transcription factor 4 (ATF4) mRNA levels were upregulated the most through the MAPK signaling pathway in the induced-PDLC group. USF2 could bind to the transcriptional initiation region of ATF4 and regulate its transcriptional activities. Additionally, the overexpression of USF2 promoted osteoblast-specific gene expression and the Alizarin red staining of PDLCs, while simultaneously overexpressing USF2 and silencing ATF4 reversed the favorable osteogenic effect of the induced-PDLCs by reducing osteoblast-specific gene expression and the Alizarin red staining level.

CONCLUSION

Our study demonstrated that USF2 could enhance the osteogenic differentiation of PDLCs by regulating ATF4 transcriptional activities, which provides a new strategy to utilize USF2 and ATF4 as potential target molecules for periodontal bone regeneration.

The Dietary Flavonoid, Luteolin, Negatively Affects Neuronal Differentiation

Luteolin, a polyphenolic plant flavonoid, has been attributed with numerous beneficial properties like anti-cancer, antioxidant, and anti-inflammatory action. Luteolin has been reported earlier to be neuroprotective in models of spinal cord injury and traumatic brain injury and also induces neurite outgrowth in PC12 cells. However, the effect of luteolin on early differentiation, which might be important for its beneficial effects, is unknown. In this report, we show that luteolin negatively affects early differentiation of embryonic stem cells, hampering the formation of embryoid bodies. At later stages of differentiation, luteolin specifically inhibits neuronal differentiation, where the expression of early neuronal markers is suppressed, whereas luteolin treatment does not inhibit expression of meso- and endodermal markers. Further, in a developing zebrafish model, luteolin treatment leads to fewer numbers of mitotic cells in the brain. These specific effects of luteolin on neuronal differentiation could possibly be due to its ability to inhibit the lysine acetyltransferase, p300, since the structurally closely related p300 non-inhibitor flavonoid, apigenin, does not inhibit neuronal differentiation. These results show that luteolin perturbs neuronal differentiation of embryonic stem cells.

Fluid shear stress promotes osteoblast proliferation through the NFATc1-ERK5 pathway

PURPOSE

Extracellular-regulated kinase 5 (ERK5) is thought to regulate osteoblast proliferation. To further understand how ERK5 signaling regulates osteoblast proliferation induced by fluid shear stress (FSS), we examined some potential signaling targets associated with ERK5 in MC3T3-E1 cells.

METHODS

MC3T3-E1 cells were treated with XMD8-92 (an ERK5 inhibitor) or Cyclosporin A (CsA, a nuclear factor of activated T cells (NFAT) c1 inhibitor) and/or exposed to 12 dyn/cm² FSS. Phosphorylated-ERK5 (p-ERK5) and expression levels of NFATc1, ERK5, E2F2, and cyclin E1 were analyzed by western blot. The mRNA levels of genes associated with cell proliferation were analyzed by Polymerase Chain Reaction (PCR) array. Subcellular localization of p-ERK5 and NFATc1 were determined by immunofluorescence. Cell proliferation was evaluated by MTT assay.

RESULTS

NFATc1 expression was up-regulated by FSS. XMD8-92 only blocked ERK5 activation; however, CsA decreased NFATc1 and p-ERK5 levels, including after FSS stimulation. Exposure to NFATc1 inhibitor or ERK5 inhibitor resulted in decreased E2F2 and cyclin E1 expression and proliferation by proliferative MC3T3-E1 cells. Furthermore, immunofluorescence results illustrated that NFATc1 induced ERK5 phosphorylation, resulting in p-ERK5 translocation to the nucleus.

CONCLUSIONS

Our results reveal that NFATc1 acts as an intermediate to promote the phosphorylation of ERK5 induced by FSS. Moreover, activated NFATc1-ERK5 signaling up-regulates the expression of E2F2 and cyclin E1, which promote osteoblast proliferation.

Anti-inflammatory effect of the Salvia sclarea L. ethanolic extract on lipopolysaccharide-induced periodontitis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Salvia sclarea L., clary, is an aromatic plant traditionally used in folk medicine for the treatment of various diseases and conditions. Although it has been primarily used as a stomachic, there are data on traditional use of S. sclarea as an agent against gingivitis, stomatitis and aphthae.

AIM OF THE STUDY

The aim of the study was to examine the effect of the S. sclarea ethanolic extract on the lipopolysaccharide (LPS)-induced periodontitis in rats from the immunological and histopathological standpoint.

MATERIAL AND METHODS

Periodontal inflammation in rats was induced by repeated injections of LPS from Escherichia coli into the interdental papilla between the first and second right maxillary molars. The extract was administered two times a day by oral gavage (200mg/kg body weight). The inflammatory status was assessed by the measurements of proinflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) of gingival tissues and descriptive analysis of histological sections of periodontium. Chemical characterization of the extract was determined using high performance liquid chromatography system (HPLC). Antioxidant activity of the extract was estimated with two in vitro complementary methods: 2,2-diphenyl-1-picrylhydrazyl and β-carotene/linoleic acid models.

RESULTS

Treatment with S. sclarea extract, compared to the untreated group of the rats, significantly diminished the process of inflammation decreasing the levels of IL-1β, IL-6 and TNF-α, reducing the gingival tissue lesions and preserving bone alveolar resorption. Considerably smaller number of inflammatory cells and larger number of fibroblasts was noticed. The administration of the extract three days earlier did not have significant preventive effects. Rosmarinic acid was the predominant compound in the extract. The extract showed strong antioxidant effects in both test systems.

CONCLUSIONS

S. sclarea extract manifested anti-inflammatory effect in LPS-induced periodontitis suggesting that it may have a role as a therapeutic agent in periodontal diseases. Having in mind that overproduction of reactive oxygen species is connected to periodontitis, the strong antioxidant capacity may be contributable to anti-inflammatory properties of the extract.