Bidirectional ephrinB2‑EphB4 signaling regulates the osteogenic differentiation of canine periodontal ligament stem cells

Tensile force promotes osteogenic differentiation via ephrinB2-EphB4 signaling pathway in orthodontic tooth movement

OBJECTIVE

To investigating whether osteogenic differentiation of osteoblasts promoted by tension force (TF) is mediated by ephrinB2-EphB4 signaling.

METHODS

TF was applied to MC3T3-E1 cells, then CCK-8 and live/dead staining were used to detect cell proliferation. Levels of osteogenic differentiation-related factors were detected by ALP staining, ARS staining, qPCR and western blot. NVP-BHG712 was used to block EphB4 receptor. Establishing a rat orthodontic tooth movement (OTM) model, ephrinB2-Fc and NVP-BHG712 were used to treat rats. Micro-CT and H&E staining were used to detect alveolar bone. Changes of MAPK pathways were detected to investigate whether they were downstream of ephrinB2-EphB4 signaling in mediating TF promote osteogenic differentiation.

RESULT

We explored the effect of TF on MC3T3-E1 cells, and found that TF significantly promoted osteogenic differentiation, but when EphB4 receptor was blocked, the promotion was inhibited. In vivo, we found that TF improved alveolar bone formation through ephrinB2-EphB4 signaling. Further investigation into the signaling pathways revealed that TF significantly increased levels of MAPK pathways, however, when EphB4 receptor was blocked, only the promotion of p-ERK1/2 was decreased.

CONCLUSION

TF promotes osteogenic differentiation through ephrinB2-EphB4 signaling and ERK1/2 pathway is a downstream of ephrinB2-EphB4 signaling partially mediate mediates TF-induced promotion of osteogenic differentiation.

Erythropoietin induces odontoblastic differentiation of human-derived pulp stem cells via EphB4-Mediated MAPK signaling pathway

OBJECTIVES

Human-derived pulp stem cells play key roles during dentinogenesis. Erythropoietin is reportedly involved in osteoblastogenesis and facilitates bone formation. However, the mechanism is still unknown. This research was to study the potential of erythropoietin in enhancing odontoblastic differentiation of human-derived pulp stem cells and to determine the underlying mechanism.

METHODS

The human-derived pulp stem cells were treated with erythropoietin, EphB4 inhibitor, and MAPK inhibitors, and the odontoblastic differentiation was measured by ALP staining, ALP activity assay, alizarin red S staining, and their quantitative analysis, and RT-qPCR of DSPP, DMP1, OCN, and RUNX2. The direct pulp capping model was established to evaluate the formation of tertiary dentin after treatment with erythropoietin. Western blot assay was conducted to assess relevant protein expressions in the phosphorylated EphB4 and MAPK pathway.

RESULTS

The results showed that erythropoietin promoted odontoblastic differentiation of human-derived pulp stem cells at 20 U/ml. Erythropoietin induced tertiary dentin formation in vivo. The potential mechanism of this was upregulating phosphorylated EphB4 and phosphorylated MAPK; furthermore, this effect could be decreased by EphB4 inhibitors, which inhibited MAPK phosphorylation. Blockage of MAPK pathways attenuated human-derived pulp stem cells' odontoblastic differentiation, suggesting that MAPK pathways are involved.

CONCLUSION

Erythropoietin induced tertiary dentin formation in vivo. And erythropoietin enhanced human-derived pulp stem cells' odontoblastic differentiation via the EphB4-mediated MAPK signaling pathway.

EphrinB2 drives osteogenic fate of adult cardiac fibroblasts in a calcium influx dependent manner

Cardiac calcification is a crucial but underrecognized pathological process, greatly increasing the risk of cardiovascular diseases. Little is known about how cardiac fibroblasts, as a central mediator, facilitate abnormal mineralization. Erythropoietin-producing hepatoma interactor B2 (EphrinB2), previously identified as an angiogenic regulator, is involved in fibroblast activation, while its role in the osteogenic differentiation of cardiac fibroblasts is unknown. Bioinformatics analysis was conducted to characterize the expression of the Ephrin family in human calcified aortic valves and calcific mouse hearts. The effects of EphrinB2 on cardiac fibroblasts to adopt osteogenic fate was determined by gain- and loss-of-function. EphrinB2 mRNA level was downregulated in calcified aortic valves and mouse hearts. Knockdown of EphrinB2 attenuated mineral deposits in adult cardiac fibroblasts, whereas overexpression of EphrinB2 promoted their osteogenic differentiation. RNA sequencing data implied that Ca2+-related S100/receptor for advanced glycation end products (RAGE) signaling may mediate EphrinB2-induced mineralization in cardiac fibroblasts. Moreover, L-type calcium channel blockers inhibited osteogenic differentiation of cardiac fibroblasts, implying a critical role in Ca2+ influx. In conclusion, our data illustrated an unrecognized role of EphrinB2, which functions as a novel osteogenic regulator in the heart through Ca2+ signaling and could be a potential therapeutic target in cardiovascular calcification.NEW & NOTEWORTHY In this study, we observed that adult cardiac fibroblasts but not neonatal cardiac fibroblasts exhibit the ability of osteogenic differentiation. EphrinB2 promoted osteogenic differentiation of cardiac fibroblasts through activating Ca2+-related S100/RAGE signaling. Inhibition of Ca2+ influx using L-type calcium channel blockers inhibited EphrinB2-mediated calcification of cardiac fibroblasts. Our data implied an unrecognized role of EphrinB2 in regulating cardiac calcification though Ca2+-related signaling, suggesting a potential therapeutic target of cardiovascular calcification.

Pathological and Therapeutic Approach to Endotoxin-Secreting Bacteria Involved in Periodontal Disease

It is widely recognized that periodontal disease is an inflammatory entity of infectious origin, in which the immune activation of the host leads to the destruction of the supporting tissues of the tooth. Periodontal pathogenic bacteria like Porphyromonas gingivalis, that belongs to the complex net of oral microflora, exhibits a toxicogenic potential by releasing endotoxins, which are the lipopolysaccharide component (LPS) available in the outer cell wall of Gram-negative bacteria. Endotoxins are released into the tissues causing damage after the cell is lysed. There are three well-defined regions in the LPS: one of them, the lipid A, has a lipidic nature, and the other two, the Core and the O-antigen, have a glycosidic nature, all of them with independent and synergistic functions. Lipid A is the "bioactive center" of LPS, responsible for its toxicity, and shows great variability along bacteria. In general, endotoxins have specific receptors at the cells, causing a wide immunoinflammatory response by inducing the release of pro-inflammatory cytokines and the production of matrix metalloproteinases. This response is not coordinated, favoring the dissemination of LPS through blood vessels, as well as binding mainly to Toll-like receptor 4 (TLR4) expressed in the host cells, leading to the destruction of the tissues and the detrimental effect in some systemic pathologies. Lipid A can also act as a TLRs antagonist eliciting immune deregulation. Although bacterial endotoxins have been extensively studied clinically and in a laboratory, their effects on the oral cavity and particularly on periodontium deserve special attention since they affect the connective tissue that supports the tooth, and can be linked to advanced medical conditions. This review addresses the distribution of endotoxins associated with periodontal pathogenic bacteria and its relationship with systemic diseases, as well as the effect of some therapeutic alternatives.

Early functional changes associated with alpha-synuclein proteinopathy in engineered human neural networks

A patterned spread of proteinopathy represents a common characteristic of many neurodegenerative diseases. In Parkinson's disease (PD), misfolded forms of α-synuclein proteins accumulate in hallmark pathological inclusions termed Lewy bodies and Lewy neurites. Such protein aggregates seem to affect selectively vulnerable neuronal populations in the substantia nigra and to propagate within interconnected neuronal networks. Research findings suggest that these proteinopathic inclusions are present at very early time points in disease development, even before clear behavioral symptoms of dysfunction arise. In this study, we investigate the early pathophysiology developing after induced formation of such PD-related α-synuclein inclusions in a physiologically relevant in vitro setup using engineered human neural networks. We monitor the neural network activity using multielectrode arrays (MEAs) for a period of 3 wk following proteinopathy induction to identify associated changes in network function, with a special emphasis on the measure of network criticality. Self-organized criticality represents the critical point between resilience against perturbation and adaptational flexibility, which appears to be a functional trait in self-organizing neural networks, both in vitro and in vivo. We show that although developing pathology at early onset is not clearly manifest in standard measurements of network function, it may be discerned by investigating differences in network criticality states.

Odontogenesis and neuronal differentiation characteristics of periodontal ligament stem cells from beagle dog

Periodontal ligament stem cells (PDLSCs) from beagle dogs had the characteristics of multi‐directional differentiation and had great application potential in tissue engineering and cell regenerative medicine. In this study, we analysed the odontogenesis and neuronal differentiation characteristics of PDLSCs in vitro. Results showed that the calcined tooth powder (CTP) and silver nanoparticles (AgNPs) additives could induce the PDLSCs into odontogenesis differentiation; besides, the immunofluorescence staining identified that the high dosage calcined tooth powder (400 μg/mL) significantly facilitated the odontogenesis associated with BMP4 expression. While the nutritional factor (L‐glutamine, NGF (nerve growth factor), bFGF (basic fibroblast growth factor), IGF‐1 (insulin‐like growth factor‐1) and EGF (epidermal growth factor)) additives were prior to induce the PDLSCs into neuronal differentiation. Simultaneously, PDLSCs had high proliferation ability with the different supplemented additives. Importantly, the Western blot results also proved the BMP4 and SMAD1 proteins were highly expressed in the induced odontoblast, while the SOX1, NCAM1, GFAP and VEGFA proteins were all obviously expressed in the induced neurons. Hence, PDLSCs had characteristics of both odontogenesis and neuronal differentiation.