GroEL triggers NLRP3 inflammasome activation through the TLR/NF-κB p-p65 axis in human periodontal ligament stem cells.

The interaction between bacteria and the host plays a vital role in the initiation and progression of systemic diseases, including gastrointestinal and oral diseases, due to the secretion of various virulence factors from these pathogens. GroEL, a potent virulence factor secreted by multiple oral pathogenic bacteria, is implicated in the damage of gingival epithelium, periodontal ligament, alveolar bone and other peripheral tissues. However, the underlying biomechanism is still largely unknown. In the present study, we verify that GroEL can trigger the activation of NLRP3 inflammasome and its downstream effector molecules, IL-1ß and IL-18, in human periodontal ligament stem cells (hPDLSCs) and resultantly induce high activation of gelatinases (MMP-2 and MMP-9) to promote the degradation of extracellular matrix (ECM). GroEL-mediated activation of the NLRP3 inflammasome requires the participation of Toll-like receptors (TLR2 and TLR4). High upregulation of TLR2 and TLR4 induces the enhancement of NF-κB (p-p65) signaling and promotes its nuclear accumulation, thus activating the NLRP3 inflammasome. These results are verified in a rat model with direct injection of GroEL. Collectively, this study provides insight into the role of virulence factors in bacteria-induced host immune response and may also provide a new clue for the prevention of periodontitis.

PDGF-AA guides cell crosstalk between human dental pulp stem cells in vitro via the PDGFR-α/PI3K/Akt axis.

AIM: To explore the influence of PDGF-AA on cell communication between human dental pulp stem cells (DPSCs) by characterizing gap junction intercellular communication (GJIC) and its potential biomechanical mechanism. METHODOLOGY: Quantitative real-time PCR was used to measure connexin family member expression in DPSCs. Cell migration and CCK-8 assays were utilized to examine the influence of PDGF-AA on DPSC migration and proliferation. A scrape loading/dye transfer assay was applied to evaluate GJIC triggered by PDGF-AA, a PI3K/Akt signalling pathway blocker (LY294002) and a PDGFR-α blocker (AG1296). Western blotting and immunofluorescence were used to test the expression and distribution of the Cx43 and p-Akt proteins in DPSCs. Scanning electron microscopy (SEM) and immunofluorescence were used to observe the morphology of GJIC in DPSCs. RESULTS: PDGF-AA promoted gap junction formation and intercellular communication between human dental pulp stem cells. PDGF-AA upregulates the expression of Cx43 to enhance gap junction formation and intercellular communication. PDGF-AA binds to PDGFR-α and activates PI3K/Akt signalling to regulate cell communication. CONCLUSIONS: This research demonstrated that PDGF-AA can enhance Cx43-mediated GJIC in DPSCs via the PDGFR-α/PI3K/Akt axis, which provides new cues for dental pulp regeneration from the perspective of intercellular communication.

Biomimetic Fibers Derived from an Equidistant Micropillar Platform Dictate Osteocyte Fate via Mechanoreception.

It is a big challenge to design a biomimetic physical microenvironment with greater similarity to in vivo tissue to observe real cell behaviors. We established a novel cell culture platform based on patterned equidistant micropillars with stiff and soft stiffnesses to mimic the changes that happened in the transition from normal to osteoporotic disease. We first demonstrated that the soft micropillar substrate decreased osteocyte synaptogenesis through synaptogyrin 1 and that this decrease was accompanied by impairment of cell mechanoperception and a decrease in cellular cytoskeletal rearrangement. We then found that the soft equidistant micropillar substrate reduced the osteocyte synaptogenesis mainly via the inactivation of Erk/MAPK signaling. We finally found that soft micropillar substrate-mediated synaptogenesis impacted the cell-to-cell communication and matrix mineralization of osteocytes. Taken together, this study provides evidence of cellular mechanical responses that are much more similar to those of real osteocytes at the bone tissue level.

Stiffened fibre-like microenvironment based on patterned equidistant micropillars directs chondrocyte hypertrophy.

Articular cartilage, composed of collagen type II as a major extracellular matrix and chondrocyte as a unique cell type, is a specialized connective tissue without blood vessels, lymphatic vessels and nerves. This distinctive characteristic of articular cartilage determines its very limited ability to repair when damaged. It is well known that physical microenvironmental signals regulate many cell behaviors such as cell morphology, adhesion, proliferation and cell communication even determine chondrocyte fate. Interestingly, with increasing age or progression of joint diseases such as osteoarthritis (OA), the major collagen fibrils in the extracellular matrix of articular cartilage become larger in diameter, leading to stiffening of articular tissue and reducing its resistance to external tension, which in turn aggravates joint damage or progression of joint diseases. Therefore, designing a physical microenvironment closer to the real tissue and thus obtaining data closer to the real cellular behaviour, and then revealing the biological mechanisms of chondrocytes in pathological states is of crucial importance for the treatment of OA disease. Here we fabricated micropillar substrates with the same topology but different stiffnesses to mimic the matrix stiffening that occurs in the transition from normal to diseased cartilage. It was first found that chondrocytes responded to stiffened micropillar substrates by showing a larger cell spreading area, a stronger enhancement of cytoskeleton rearrangement and more stability of focal adhesion plaques. The activation of Erk/MAPK signalling in chondrocytes was detected in response to the stiffened micropillar substrate. Interestingly, a larger nuclear spreading area of chondrocytes at the interface layer between the cells and top surfaces of micropillars was observed in response to the stiffened micropillar substrate. Finally, it was found that the stiffened micropillar substrate promoted chondrocyte hypertrophy. Taken together, these results revealed the cell responses of chondrocytes in terms of cell morphology, cytoskeleton, focal adhesion, nuclei and cell hypertrophy, and may be beneficial for understanding the cellular functional changes affected by the matrix stiffening that occurs during the transition from a normal state to a state of osteoarthritis.

The role of fibroblast growth factor 7 in cartilage development and diseases.

Fibroblast growth factor 7 (FGF7), also known as keratinocyte growth factor (KGF), shows a crucial biological significance in tissue development, wound repair, tumorigenesis, and immune reconstruction. In the skeletal system, FGF7 directs the cellular synaptic extension of individual cells and facilities functional gap junction intercellular communication of a collective of cells. Moreover, it promotes the osteogenic differentiation of stem cells via a cytoplasmic signaling network. For cartilage, reports have indicated the potential role of FGF7 on the regulation of key molecules Cx43 in cartilage and Runx2 in hypertrophic cartilage. However, the molecular mechanism of FGF7 in chondrocyte behaviors and cartilage pathological process remains largely unknown. In this review, we systematically summarize the recent biological function of FGF7 and its regulatory role on chondrocytes and cartilage diseases, especially through the hot focus of two key molecules, Runx2 and Cx43. The current knowledge of FGF7 on the physiological and pathological processes of chondrocytes and cartilage provides us new cues for wound repair of cartilage defect and therapy of cartilage diseases.

Platelet-derived growth factor PDGF-AA upregulates connexin 43 expression and promotes gap junction formations in osteoblast cells through p-Akt signaling.

Gap junctions, which are mainly composed of connexin units, play an indispensable role in cell morphogenesis, proliferation, migration, adhesion and differentiation of osteoblast lineage cells, and thus mediate bone development, homeostasis and disease occurrence. Platelet-derived growth factor-AA (PDGF-AA) is proved to have a great influence on osteoblast cell lines and is widely applied in the field of bone defect and wound healing. However, the role of PDGF-AA on gap junction formation in the osteoblast lineage remains elusive. In the current study, we aimed to investigate the impact of PDGF-AA on gap junction formation and cell-to-cell communication in the osteoblast lineage and explore its underlying biomechanism. We first found that PDGF-AA promoted cell proliferation and thus increased gap junction formations in living primary osteoblasts and MC3T3-E1 cells through scrape loading and dye transfer (SL/DT) assay. We then confirmed that PDGF-AA enhanced gap junction formations through up-regulation of connexin 43 (Cx43). We next detected the activation of p-Akt signaling in primary osteoblasts and MC3T3-E1 cells that were induced by PDGF-AA. Through inhibitory experiments, we further confirmed that PDGF-AA-mediated gap junction formation occurred via the activation of PI3K/Akt signaling. Taking together, our results provided evidences that PDGF-AA promoted gap junction formation in the osteoblast lineage through p-Akt signaling, which helped to understand the role of PDGF-AA in bone regeneration and diseases.

IL-10 enhances cell-to-cell communication in chondrocytes via STAT3 signaling pathway.

Gap junction intercellular communication (GJIC) allows the transfer of material, message and energy between cells, which influences cell behaviors including cell proliferation, migration, differentiation and apoptosis and determines cell fate. Interleukin-10 (IL-10), a versatile cytokine, attracts more and more attention in the cartilage pathology such as osteoarthritis (OA) due to its potential in anti-inflammation and wound repair. However, whether IL-10 can mediate GJIC in chondrocytes remains elusive. In the current study, we aimed to explore the role of IL-10 on GJIC and its underlying mechanism. We found that IL-10 can promote GJIC in living chondrocytes. IL-10-enhanced GJIC in chondrocytes was dependent on the up-regulation of connexin 43 (Cx43). Knockdown experiment based on siRNA interference then confirmed that IL-10-enhanced GJIC required participation of IL-10 receptor 1 (IL-10R1). IL-10 activated signal transducer and activator of transcription 3 (STAT3) signaling and promoted the nuclear accumulation of p-STAT3 through IL-10 receptor 1. Inhibitor experiment further confirmed the importance of STAT3 signaling in IL-10-mediated GJIC. Taking together, our results provided a thorough process of IL-10-modulated cell-to-cell communication in chondrocytes and established a bridge between inflammatory factor, IL-10, and GJIC, which can increase our understanding about the physiology and pathology of cartilage.

Engineering p-Band Center of Oxygen Boosting H+ Intercalation in δ-MnO2 for Aqueous Zinc Ion Batteries.

In aqueous zinc ion batteries (ZIBs), the H+ intercalation possesses superior electrochemical kinetics with excellent rate capability, however, precisely modulating H+ intercalation has been still challenging. Herein, a critical modification of pre-intercalating metal ions in the MnO2 interlayer (M-MnO2 ) with controllable p-band center (ϵp ) of O is reported to modulate the H+ intercalation. The modulation of metal-O bond type and covalency degree on the average charge of O atom results in optimized ϵp and H+ adsorption energy for M-MnO2 , thus promoting the balance between H+ adsorption and desorption, which plays a determinant role on H+ intercalation. The optimized Cu-MnO2 delivers superior rate capability with the capacity of 153 mAh g-1 at a high rate of 3 A g-1 after 1000 cycles. This work demonstrates that ϵp could be a significant descriptor for H+ intercalation, and tuning ϵp effectively increases H+ intercalation contribution with excellent rate capability in ZIBs.

Enriching Oxygen Vacancy Defects via Ag-O-Mn Bonds for Enhanced Diffusion Kinetics of δ-MnO2 in Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) have received great attention due to their environmental friendliness and high safety. However, cathode materials with slow diffusion dynamics and dissolution in aqueous electrolytes hindered their further application. To address these issues, in this work, a MnO2-2 cathode doped with 1.12 wt % Ag was prepared, and after 1000 cycles of charge/discharge at 1 A·g-1, the capacity remained at 114 mA·h·g-1 (only 57.7 mA·h·g-1 for pristine MnO2). Cyclic voltammetry (CV), the galvanostatic intermittent titration technique (GITT), the electrochemical quartz crystal microbalance (EQCM) method, and density functional theory (DFT) calculation on pristine δ-MnO2 and MnO2-2 also proved the superior performance of MnO2-2. More investigation disclosed that its superior performance is attributed to the improved diffusion kinetics of the cathode brought by the enriched oxygen vacancy defects due to the formation of Ag-O-Mn bonds. Meanwhile, the kinetic mechanism of the Zn/MnO2-2 cell can be described as a reversible process of the dissolution/precipitation of the ZHS phase and consequent insertion/extraction of Zn2+ and H3O+. Herein, the primary issues of ZIB cathode materials have been addressed and solved to a certain extent. More importantly, such a modification in the design of the advanced manganese-based aqueous ZIB cathode materials can provide further insight and facilitate the development and application of this large-scale energy storage system in the near future.

TGF-ß2 increases cell-cell communication in chondrocytes via p-Smad3 signalling.

Connexin 43 (Cx43)-mediated gap junction intercellular communication (GJIC) plays a crucial role in the pathology and physiology of joint tissues. Transforming growth factor-ß2 (TGF-ß2), one of the potent regulatory factors in chondrocytes, plays a key role in the regulation of cell cycle and development of joint diseases. However, it is still unknown how TGF-ß2 mediates GJIC in chondrocytes. The aim of this study was to explore the potential mechanism by which TGF-ß2 regulates GJIC in chondrocytes. CCK-8 assays and scratch assays were performed to define the role of TGF-ß2 on cell proliferation and migration. The scrape loading/dye transfer assay and scanning electron microscopy (SEM) were used to verify the effect of TGF-ß2 on GJIC between chondrocytes. qPCR was performed to analyse the expression of genes in the gap junction protein family in chondrocytes. The expression of the Cx43 protein and phosphorylated Smad3 (p-Smad3) was evaluated by western blot assay. Immunofluorescence staining was used to explore p-Smad3 signalling pathway activation and Cx43 distribution. From these experiments, we found that the Cx43 protein was the most highly expressed member of the gap junction protein family in chondrocytes. We also found that TGF-ß2 facilitated cell-to-cell communication in chondrocytes by upregulating Cx43 expression in chondrocytes. Finally, we found that TGF-ß2 activated Smad3 signalling and promoted the nuclear aggregation of p-Smad3. Inhibition experiments by SIS3 also confirmed that TGF-ß2-mediated GJIC through p-Smad3 signalling. For the first time, this study confirmed that TGF-ß2 could regulate the formation of Cx43-mediated GJIC in chondrocytes via the canonical p-Smad3 signalling pathway.

A New Co-Free Ni-Rich LiNi0.8Fe0.1Mn0.1O2 Cathode for Low-Cost Li-Ion Batteries.

In recent years, with the rapid development of electric vehicles, the ever-fluctuating cobalt price has become a decisive constraint on the supply chain of the lithium-ion (Li-ion) battery industry. To address these challenges, a new and unreported cobalt-free (Co-free) material with a general formula of LiNi0.8Fe0.1Mn0.1O2 (NFM) is introduced. This Co-free material is synthesized via the coprecipitation method and examined by using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) to investigate the morphological, crystal-structure, and electrochemical properties. The NFM cathode can deliver a specific capacity of 202.6 mA h g-1 (0.1C, 3.0-4.5 V), a specific energy capacity of 798.8 W h kg-1 in material level (0.1C, 3.0-4.5 V), a reasonable rate capability, and a stable cycling performance (81.1% discharge capacity retention after 150 cycles at 10C, 3.0-4.3 V). Although the research on this subject is still in its early stage, the capability of this novel cathode material as a practical candidate for applications in next-generation Co-free lithium-ion batteries (LIBs) is highlighted in this study.

The expression of zebrafish NAD(P)H:quinone oxidoreductase 1(nqo1) in adult organs and embryos.

NQO1, NAD(P)H: quinone oxidoreductase 1, was first identified in rat and its role has been extensively studied. Even the roles of NQO1 in the maintenance of physiological function and disease were largely addressed, whether the tissue specific functions of the NQO1 in organ development remains unknown. In the current study, we identified two NQO1 isoforms (isoform 1 and isoform 2) and examined the expression of nqo1 variants in adult zebrafish organs and embryos at different stages. In adult organs, RT-PCR result indicated that nqo1 variant 1 was mainly expressed in stomach and intestine, while nqo1 variant 2 was expressed in all organs investigated except for heart. Further, RT-PCR result showed that the nqo1 variant 1 and variant 2 were expressed at all the embryonic stages, but nqo1 variant 1 expression level was much lower than that of nqo1 variant 2. To specifically examine the expression pattern of these two different nqo1 variants, we did whole mount in situ hybridization and the results demonstrated that, both of them were maternally expressed at 8-cell stage, and they were all expressed ubiquitously at early stage. At 24 hpf, nqo1 variant 2 was mainly expressed in yolk cells, and slightly in head and eyes. At 48 hpf, nqo1 variant 2 was restricted in lateral line neuromasts. From 72 hpf to 144 hpf, nqo1 variant 2 was mainly restricted in branchial arch, liver, swimming bladder and lateral line neuromasts, while from 124 hpf to 192 hpf, nqo1 variant 2 only restricted in liver, and disappeared in lateral line neuromasts. On the contrary, at the late embryonic stage, nqo1 variant 1 was only expressed in liver and swimming bladder while not in branchial arch and lateral line neuromasts. In conclusion, we systematically analyzed the expression pattern of nqo1 variant 1 and variant 2 in zebrafish at different embryonic stages, and our data implied the possible role of nqo1 in regulating liver, branchial arch and lateral neuromasts development.

The synthesis of a Cu(ii) Schiff base complex using a bidentate N2O2 donor ligand: crystal structure, photophysical properties, and antibacterial activities.

In this paper, a new mononuclear Cu(ii) complex was synthesized by using a bidentate N2O2 Schiff base ligand, (E)-2-bromo-4-chloro-6-[(2,6-dimethylphenylimino)methyl]phenol (HL), with a copper(ii) salt in a methanol solvent. The structures of the HL ligand and the complex were characterized by Fourier transform infrared (FTIR) spectroscopy, single crystal X-ray diffraction (SCXD), and elemental analysis (EA). The Cu(ii) center in the complex is four-coordinated by a bidentate N2O2 donor ligand, forming slightly distorted square planar geometry. The detailed studies of their photophysical properties such as UV-Vis and fluorescence were done and the X-ray diffraction (XRD) patterns were investigated in the powder forms. Density functional theory calculations were carried out on both the HL ligand and the Cu(ii) complex to investigate the changes in the structural parameters and energies of the HOMO and LUMO. The results demonstrated that the HOMO and LUMO were effectively separated with the benzene ring of 2,6-dimethylbenzenamine as the donor unit and the benzene ring of 3-bromo-5-chlorosalicylaldehyde as well as the chelate ring as the acceptor unit. The effective HOMO-LUMO separation helps induce intramolecular charge transfer from the HOMO to the LUMO. The HOMO-LUMO energy gap become smaller when the Schiff base ligand coordinated with Cu(ii) ions, which was most likely due to the Cu(ii) perturbation effect. These theoretical calculations supported the experimentally observed results. The antibacterial activities of the HL ligand and the Cu(ii) complex were studied on Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The obtained data confirmed their potent antimicrobial activity and the Cu(ii) complex had the MIC value of 1.25 mmol L-1 against Escherichia coli.

2-Benzyl-imino-meth-yl-6-bromo-4-chloro-phenol.

The title mol-ecule, C(14)H(11)BrClNO, adopts a trans configuration with respect to the C=N double bond. The dihedral angle between the two aromatic rings is 70.4 (5)°. An intra-molecular O-H⋯N hydrogen bond is observed between the hydroxyl and imine groups.

Bis[2-(benzyl-imino-meth-yl)-4-chloro-phenolato-κN,O]nickel(II).

In the mononuclear centrosymmetric title compound, [Ni(C(14)H(11)ClNO)(2)], the Ni(II) atom, lying on a center of symmetry, is four-coordinated by two O atoms and two N atoms from two Schiff base ligands, forming a slightly distorted square-planar environment. The dihedral angle between the two aromatic rings of the ligand is 72.0 (2)°. No significant hydrogen bonding or π-π stacking inter-actions are observed.

Bis(4-chloro-2-formyl-phenolato)nickel(II).

The asymmetric unit of the title compound, [Ni(C(7)H(4)ClO(2))(2)], contains one half-mol-ecule. The Ni(II) ion, lying on an inversion centre, is four-coordinated by O atoms of 5-chloro-salicylaldehydate ligands in a square-planar geometry.

Bis[µ-2-(benzyl-imino-meth-yl)-4-chloro-phenolato]bis[chloridocopper(II)].

The title complex, [Cu(2)(C(14)H(11)ClNO)(2)Cl(2)], has a centrosymmetric dinuclear structure where two symmetry-related copper(II) metal centres are bridged by the O atoms of two phen-oxy groups. Each copper(II) centre displays a distorted tetra-hedral coordination provided by one N atom and two O atoms from two Schiff base ligands and by one Cl atom. The Cu⋯Cu separation is 3.0702 (9) Å.