Dihydromyricetin enhances the osteogenic differentiation of human bone marrow mesenchymal stem cells in vitro partially via the activation of Wnt/β‐catenin signaling pathway

Substantial evidence has demonstrated that the decreased osteogenic differentiation of bone mesenchymal stem cells (BMSCs) is closely related to bone metabolic diseases. Thus, it is very important to develop several potentially useful therapeutic agents to enhance BMSC osteogenesis. Flavonoids show promise in enhancing bone mass. Dihydromyricetin (DMY), a type of flavonoid, has not yet been investigated regarding its effects on BMSC osteogenesis. To investigate the effects of DMY on osteogenesis, human BMSCs were induced with or without DMY. We found that DMY (0.1–50 μm ) exhibited no cytotoxic effect on proliferation, but increased alkaline phosphatase activity, osteoblast‐specific gene expression, and mineral deposition. It also enhanced active β‐catenin expression and reduced dickkopf‐1(DKK1) and sclerostin expression. The Wnt/β‐catenin signaling pathway inhibitor (DKK1 and β‐catenin‐specific siRNA) decreased the enhanced bone mineral formation caused by DMY. Taken together, these findings reveal that DMY enhances osteogenic differentiation of human BMSCs partly through Wnt/β‐catenin in vitro.     

Targeting Wnt/β‐catenin by anthelmintic drug niclosamide overcomes paclitaxel resistance in esophageal cancer

Esophageal cancer is an aggressive malignancy, and its current treatment strategies are plagued with high rates of recurrence. In this work, we demonstrate that niclosamide, an anthelmintic drug, is a potential sensitizing candidate for overcoming chemoresistance in esophageal cancer. Using a panel of esophageal cancer cell lines and normal cells, we show that niclosamide has anti‐esophageal cancer activity and is likely to be less effective against normal esophageal epithelial and fibroblast cells. The combination of niclosamide with paclitaxel results in much greater efficacy than paclitaxel alone, suggesting that niclosamide is active against esophageal cancer cells that are resistant to paclitaxel. This is further confirmed by our results that niclosamide is effective in inhibiting proliferation and inducing apoptosis in paclitaxel‐resistant esophageal cancer cells. In line with the findings obtained from in vitro cell culture system, niclosamide augments the in vivo efficacy of paclitaxel and significantly arrests paclitaxel‐resistant esophageal cancer growth without causing toxicity in mice. Mechanistically, we show that niclosamide decreases β‐catenin level and activity, and inhibits phosphorylation of STAT3 and mTORC1 substrate 70S6K. Stabilization of β‐catenin level by Wnt activator lithium chloride (LiCl) significantly abolishes the inhibitory effects of niclosamide in inhibiting proliferation and survival but not suppressing phosphorylation of STAT3 and 70S6K in paclitaxel‐resistant esophageal cancer cells, suggesting that niclosamide sensitizes esophageal cancer cell to paclitaxel mainly through inhibiting Wnt/β‐catenin. Our work demonstrates the efficacy of niclosamide and its underlying mechanism in paclitaxel‐resistant esophageal cancer. Our work emphasizes that Wnt/β‐catenin inhibition is a sensitizing strategy in esophageal cancer.     

Combination of cord blood‐derived human hepatic progenitors and hepatogenic factors strongly improves recovery after acute liver injury in mice through modulation of the Wnt/β‐catenin signaling

Cell therapy represents a promising alternative strategy for end‐stage liver disease, and hepatic progenitors are the best candidates. The possibility to maximize the paracrine effects of transplanted cells represents a great potential benefit for cell therapy success. We studied how cell type and microenvironment modulate the Wnt/β‐catenin signaling in vitro and in vivo. In vitro, the onset of hepatocyte commitment was characterized by the presence of nuclear truncated β‐catenin. In vivo, we analyzed the effect of human hepatic progenitors on damage recovery and functional regeneration in a mouse model of acute liver injury, either in combination or in absence of a selected mix of hepatogenic factors. Animals injected with human hepatic progenitors and hepatogenic factors showed improved engraftment triggering the Wnt/β‐catenin signaling cascade. Human hepatic progenitors expressing the human oval cell marker OV6 displayed a consistent colocalization with β‐catenin and colocalized with Wnt1 main ligand of the canonical pathway. Wnt5a, on the contrary, was expressed in distinct liver cell populations. Epithelial mesenchymal transition‐related markers showed enhanced expression and wider distribution, and the hepato‐mesenchymal population Thy1 + CK19? was also present. Control animals injected with hepatogenic factors alone exhibited higher β‐catenin, decreased Wnt5a levels, and persistent proliferation of the hepato‐mesenchymal population. In conclusion, the combination of human hepatic progenitors with selected hepatogenic factors creates a positive synergy with local microenvironment, ameliorates cell engraftment, stimulates and accelerates regenerative process, and improves the rescue of hepatic function by modulating the Wnt/βcatenin signaling and activating hepato‐mesenchymal population.     

The profibrotic cytokine transforming growth factor‐β1 increases endothelial progenitor cell angiogenic properties

Summary. Background: Transforming growth factor‐β1 (TGF‐β1) is a profibrotic cytokine that plays a major role in vascular biology, and is known to regulate the phenotype and activity of various vascular cell populations. Because most fibrotic diseases, such as idiopathic pulmonary fibrosis (IPF), are associated with vascular remodeling, and as endothelial progenitor cells (EPCs) may be involved in this process, we investigated the impact of TGF‐β1 modulation of EPC angiogenic properties. Methods: TGF‐β1 plasma levels were determined in 64 patients with IPF and compared with those in controls. The effect of TGF‐β1 on angiogenesis was studied in vivo in a Matrigel plug model and in vitro on endothelial colony‐forming cells (ECFCs). We studied the effects of inhibiting the expression of the three main receptors of TGF‐β1 in ECFCs by using short interfering RNA. Results: Total TGF‐β1 plasma levels were significantly increased in patients with IPF as compared with controls (P < 0.0001). TGF‐β1 had proangiogenic effects in vivo by increasing hemoglobin content and blood vessel formation in Matrigel plugs implanted in C57/Bl6 mice, and in vitro by enhancing ECFC viability and migration. The effects were abolished by silencing the three main TGF‐β1 receptors. Conclusions: TGF‐β1 is proangiogenic in vivo and induces ECFC angiogenic properties in vitro, suggesting that TGF‐β1 may play a role during vascular remodeling in fibrotic disease states via EPCs.     

B淋巴增殖性疾病的SOX11、cyclin D1、cyclin D2和cyclin D3的表达研究

目的 探讨各B淋巴增殖性疾病(B-LPD)中SOX11、cyclin D1、cyclin D2和cyclin D3表达的差异和相关性,以及与慢性淋巴细胞白血病(CLL)患者临床特征的关系.方法 采用实时定量逆转录PCR(qRT-PCR)技术检测154例B-LPD患者与12例健康对照SOX11、cyclin D1、cyc...     

Effects of variation in the human α2A‐ and α2C‐adrenoceptor genes on cognitive tasks and pain perception

Background: The mechanisms underlying interindividual variability in pain perception and cognitive responses are undefined but highly heritable. α_2C‐ and α_2A‐adrenergic receptors regulate noradrenergic activity and are important mediators of pain perception and analgesia. We hypothesized that common genetic variants in these genes, particularly the ADRA2C 322–325 deletion variant, affect pain perception or cognitive responses. Methods: We studied 73 healthy subjects (37 Caucasians and 36 African–Americans) aged 25.4 ± 4.6 years. Pain response to a cold pressor test was measured using a 10 cm visual analog scale and again on the next day, after three infusions of the selective α₂‐agonist dexmedetomidine. Standardized cognitive tests were administered at baseline and after each infusion. The contribution of ADRA2C deletion genotype, dexmedetomidine concentration, and other covariates to pain perception and cognitive responses was determined using multiple linear regression models. Secondary analysis examined the effects of ADRA2A and other ADRA2C variants on pain perception. Results: ADRA2C Del homozygotes had higher pain scores in response to cold at baseline (6.3 ± 1.8 cm) and after dexmedetomidine (5.6 ± 2.2 cm) than insertion allele carriers (4.6 ± 2.1 cm [baseline] and 3.8 ± 1.9 cm [after dexmedetomidine]; adjusted P‐values = 0.019 and 0.004, respectively). Cognitive responses were unrelated to ADRA2C Ins/Del genotype. None of the other ADRA2A and ADRA2C variants was significantly related to cold pain sensitivity before dexmedetomidine; after dexmedetomidine, ADRA2A rs1800038 was marginally associated (P = 0.03). Conclusion: The common ADRA2C del322–325 variant affected pain perception before and after dexmedetomidine but did not affect other cognitive responses, suggesting that it contributes to interindividual variability in pain perception.     

Electromagnetic fields counteract IL‐1β activity during chondrogenesis of bovine mesenchymal stem cells

Osteoarthritis (OA) is a common joint disease associated with articular cartilage degeneration. To improve the therapeutic options of OA, tissue engineering based on the use of mesenchymal stem cells (MSCs) has emerged. However, the presence of inflammatory cytokines, such as interleukin‐1β (IL‐1β), during chondrogenesis reduces the efficacy of cartilage engineering repair procedures by preventing chondrogenic differentiation. Previous studies have shown that electromagnetic fields (EMFs) stimulate anabolic processes in OA cartilage and limit IL‐1β catabolic effects. We investigated the role of EMFs during chondrogenic differentiation of MSCs, isolated from bovine synovial fluid, in the absence and presence of IL‐1β. Pellets of MSCs were differentiated for 3 and 5 weeks with transforming growth factor‐β3 (TGFβ3), in the absence and presence of IL‐1β and exposed or unexposed to EMFs. Biochemical, quantitative real‐time RT–PCR and histological results showed that EMFs alone or in the presence of TGFβ3 play a limited role in promoting chondrogenic differentiation. Notably, in the presence of IL‐1β and TGFβ3 a recovery of proteoglycan (PG) synthesis, PG content and aggrecan and type II collagen mRNA expression in the EMF‐exposed compared to unexposed pellets was observed. Also, histological and immunohistochemical results showed an increase in staining for alcian blue, type II collagen and aggrecan in EMF‐exposed pellets. In conclusion, this study shows a significant role of EMFs in counteracting the IL‐1β‐induced inhibition of chondrogenesis, suggesting EMFs as a therapeutic strategy for improving the clinical outcome of cartilage engineering repair procedures, based on the use of MSCs. Copyright © 2012 John Wiley & Sons, Ltd.     

A role for adhesion and degranulation‐promoting adapter protein in collagen‐induced platelet activation mediated via integrin α2β1

Summary. Background: Collagen‐induced platelet activation is a key step in the development of arterial thrombosis via its interaction with the receptors glycoprotein (GP)VI and integrin α₂β₁. Adhesion and degranulation‐promoting adapter protein (ADAP) regulates α_IIbβ₃ in platelets and α_Lβ₂ in T cells, and is phosphorylated in GPVI‐deficient platelets activated by collagen. Objectives: To determine whether ADAP plays a role in collagen‐induced platelet activation and in the regulation and function of α₂β₁. Methods: Using ADAP^?/? mice and synthetic collagen peptides, we investigated the role of ADAP in platelet aggregation, adhesion, spreading, thromboxane synthesis, and tyrosine phosphorylation. Results and Conclusions: Platelet aggregation and phosphorylation of phospholipase Cγ2 induced by collagen were attenuated in ADAP^?/? platelets. However, aggregation and signaling induced by collagen‐related peptide (CRP), a GPVI‐selective agonist, were largely unaffected. Platelet adhesion to CRP was also unaffected by ADAP deficiency. Adhesion to the α₂β₁‐selective ligand GFOGER and to a peptide (III‐04), which supports adhesion that is dependent on both GPVI and α₂β₁, was reduced in ADAP^?/? platelets. An impedance‐based label‐free detection technique, which measures adhesion and spreading of platelets, indicated that, in the absence of ADAP, spreading on GFOGER was also reduced. This was confirmed with non‐fluorescent differential‐interference contrast microscopy, which revealed reduced filpodia formation in ADAP^?/? platelets adherent to GFOGER. This indicates that ADAP plays a role in mediating platelet activation via the collagen‐binding integrin α₂β₁. In addition, we found that ADAP^?/? mice, which are mildly thrombocytopenic, have enlarged spleens as compared with wild‐type animals. This may reflect increased removal of platelets from the circulation.     

Antibacterial and β‐Lactamase Inhibitory Activity of Monocyclic β‐Lactams

Due to the widespread emergence of resistant bacterial strains, an urgent need for the development of new antibacterial agents with novel modes of action has emerged. The discovery of naturally occurring monocyclic β‐lactams in the late 1970s, mainly active against aerobic Gram‐negative bacteria, has introduced a new approach in the design and development of novel antibacterial β‐lactam agents. The main goal was the derivatization of the azetidin‐2‐one core in order to improve their antibacterial potency, broaden their spectrum of activity, and enhance their β‐lactamase stability. In that respect, our review covers the updates in the field of monocyclic β‐lactam antibiotics during the last three decades, taking into account an extensive collection of references. An overview of the relationships between the structural features of these monocyclic β‐lactams, classified according to their N‐substituent, and the associated antibacterial or β‐lactamase inhibitory activities is provided. The different paragraphs disclose a number of well‐established classes of compounds, such as monobactams, monosulfactams, monocarbams, monophosphams, nocardicins, as well as other known representative classes. Moreover, this review draws attention to some less common but, nevertheless, possibly important types of monocyclic β‐lactams and concludes by highlighting the recent developments on siderophore‐conjugated classes of monocyclic β‐lactams.     

Improvements in endotoxemic syndromes using a disintegrin,rhodostomin, through integrin αvβ3‐dependent pathway

Summary. Background and objectives: Septic shock is a major cause of morbidity and mortality in intensive care units, but there is still no effective therapy for the patients. We evaluated the effects of rhodostomin (Rn), an Arg‐Gly‐Asp‐containing snake venom disintegrin, on lipopolysaccharide (LPS)‐activated phagocytes in vitro and LPS‐induced endotoxemia in vivo. Methods and results: Rn inhibited adhesion, migration, cytokine production and mitogen‐activated protein kinase (MAPK) activation of macrophage induced by LPS. Flow cytometric analysis revealed that Rn specifically blocked anti‐αv mAb binding to RAW264.7. Besides inhibiting MAPK activation of THP‐1, Rn bound to LPS‐activated THP‐1 and specifically blocked anti‐αvβ3 mAb binding to THP‐1. Binding assays proved that integrin αvβ3 was the binding site for rhodostomin on phagocytes. Rn reversed the enhancement of fibronectin and vitronectin on LPS‐induced monocyte adhesion and cytokine release. Transfection of integrin αv siRNA also inhibited LPS‐induced activation of monocyte, and Rn exerted no further inhibitory effect. Furthermore, Rn significantly decreased the production of tumor necrosis factor‐α (TNF‐a), interleukin (IL)‐6, ‐1β and ‐10 and attenuated cardiovascular dysfunction, including blood pressure and heart pulse, and thrombocytopenia in LPS‐induced endotoxemic mice. Rn also protected against tissue inflammation as evidenced by histological examination. Conclusions: Rn may interact with αvβ3 integrin of monocytes/macrophages leading to interfere with the activation of phagocytes triggered by LPS. These results suggest that the protective function of Rn in LPS‐induced endotoxemia may be attributed to its anti‐inflammation activities in vivo.