No abstract

The P2X7 receptor, an ATP‐gated ion channel, is critical for cancer cell growth, invasiveness, and angiogenesis. Previous studies indicate that P2X7 regulates osteoblast proliferation and osteodeposition and that high P2X7 expression has a pro‐growth effect in osteosarcoma. However, how it functions in osteosarcoma cell growth and metastasis is not clear. Thus, we elucidated molecular mechanisms of P2X7‐dependent positive regulation of osteosarcoma cell proliferation, invasion, migration, epithelial to mesenchymal transition (EMT), and angiogenesis using in vitro and in vivo models. We confirm that P2X7 is highly‐expressed in human osteosarcoma tumor tissues and HOS/MNNG, MG63, U2OS, SW1353 and SAOS‐2 cell lines. P2X7 receptor stimulation enhanced HOS/MNNG and SAOS‐2 cell proliferation, migration and invasion; but knockdown of P2X7 expression or receptor inhibition had opposite effects. P2X7 positively regulated glycogen content, epithelial to mesenchymal transition and stemness of HOS/MNNG cells. P2X7 activation promoted PI3K/Akt/GSK3β/β‐catenin and mTOR/HIF1α/VEGF signaling, thereby mediating pro‐tumor effects of osteosarcoma cells. Consistent with data from in vitro experiments, systemic administration of P2X7 agonist induced tumor growth, metastasis and tumor‐associated bone destruction in osteosarcoma‐bearing nude mice, whereas a P2X7 antagonist reversed these effects. Thus, the P2X7 receptor participates in regulation of osteosarcoma growth and metastasis and we offer evidence that P2X7 may be a promising therapeutic target for treating osteosarcoma.

BackgroundPneumonia is a leading infectious disease killer worldwide, yet the burden in China is not well understood as much of the data is published in the non-English literature.Methodology/Principal FindingsWe systematically reviewed the Chinese- and English-language literature for studies with primary data on pneumonia incidence and mortality in mainland China. Between 1985 and 2008, 37 studies met the inclusion criteria. The quality of the studies was highly variable. For children <5 years, incidence ranged from 0.06–0.27 episodes per person-year and mortality ranged from 184–1,223 deaths per 100,000 population. Overall incidence and mortality were stable or decreased over the study period and were higher in rural compared to urban areas.Conclusions/SignificancePneumonia continues to be a major public health challenge in young children in China, and estimates of pneumonia incidence and mortality vary widely. Reliable surveillance data and new prevention efforts may be needed to achieve and document additional declines, especially in areas with higher incidence and mortality such as rural settings.

An imbalance in the osteogenesis and adipogenesis of bone marrow-derived stromal cells (BMSCs) is a crucial pathological factor in the development of osteoporosis. Growing evidence suggests that extracellular nucleotide signaling involving the P2 receptors plays a significant role in bone metabolism. The aim of the present study was to investigate the effects of uridine triphosphate (UTP) on the osteogenic and adipogenic differentiation of BMSCs, and to elucidate the underlying mechanisms. The differentiation of the BMSCs was determined by measuring the mRNA and protein expression levels of osteogenic- and adipogenic-related markers, alkaline phosphatase (ALP) staining, alizarin red staining and Oil Red O staining. The effects of UTP on BMSC differentiation were assayed using selective P2Y receptor antagonists, small interfering RNA (siRNA) and an intracellular signaling inhibitor. The incubation of the BMSCs with UTP resulted in a dose-dependent decrease in osteogenesis and an increase in adipogenesis, without affecting cell proliferation. Significantly, siRNA targeting the P2Y2 receptor prevented the effects of UTP, whereas the P2Y6 receptor antagonist (MRS2578) and siRNA targeting the P2Y4 receptor had little effect. The activation of P2Y receptors by UTP transduced to the extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. This transduction was prevented by the mitogen-activated protein kinase inhibitor (U0126) and siRNA targeting the P2Y2 receptor. U0126 prevented the effects of UTP on osteogenic- and adipogenic-related gene expression after 24 h of culture, as opposed to 3 to 7 days of culture. Thus, our data suggest that UTP suppresses the osteogenic and enhances the adipogenic differentiation of BMSCs by activating the P2Y2 receptor. The ERK1/2 signaling pathway mediates the early stages of this process.

The etiology of osteoarthritis (OA) is complex and multifaceted. Osteoarthritis is a chronic and progressive disease of the joints that is characterized by the degradation of articular cartilage. A disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5) is the major aggrecanase in cartilage. The aim of this study was to evaluate the effect of ADAMTS-5 knockdown on cartilage degradation. Rat articular chondrocytes were transfected with lentivirus‑mediated ADAMTS-5 small interfering RNA (siRNA) or with empty vector control plasmid DNA (as the control). The suppression efficiency was measured using real-time polymerase chain reaction (RT-PCR) and western blot analysis. We then selected the most effective siRNA (siRNA1) and constructed the lentivirus-mediated siRNA targeting ADAMTS-5 for stable transfection. An animal model of OA was created using male Sprague-Dawley rats. OA was induced by performing anterior cruciate ligament transection (ACL-T) and partial medial meniscectomy (PM). The animals (n=80, weight 250‑300 g) received an intra‑articular injection of the empty vector control plasmid DNA or lentivirus‑mediated ADAMTS-5 siRNA1 (20 µl, 1x108 TU/ml). The progression of OA was analyzed using Osteoarthritis Research Society International (OARSI) scores. Compared with the control, ADAMTS-5 gene expression was decreased by approximately 80% by siRNA1 in a monolayer culture of chondrocytes. The intra‑articular injection of lentivirus‑mediated ADAMTS-5 siRNA1 in vivo resulted in the downregulation of ADAMTS-5 protein expression and improved OARSI scores (p<0.05). A single injection of lentivirus‑mediated ADAMTS‑5 siRNA prevented the degradation of articular cartilage. This method may provide a novel therapeutic strategy for the treatment of human OA.

Background The COVID-19 outbreak in late December 2019 has quickly emerged into pandemic in 2020. We aimed to describe the epidemiology and clinical characteristics of hospitalized COVID-19 patients, and to investigate the potential risk factors for COVID-19 severity. Method 1663 hospitalized patients with laboratory-confirmed diagnosed COVID-19 from Tongji Hospital between January 14, 2020, and February 28, 2020 were included in the present study. Demographic information, exposure history, medical history, comorbidities, signs and symptoms, chest computed tomography (CT) scanning, severity of COVID-19 and laboratory findings on admission were collected from electronic medical records. Multivariable logistic regression was used to explore the association between potential risk factors with COVID-19 severity. Results In the present study, the majority (79%) of 1663 COVID-19 patients were aged over 50 years old. A total of 2.8% were medical staff, and an exposure history of Huanan seafood market was document in 0.7%, and 7.4% were family infection. Fever (85.8%), cough (36.0%), fatigue (23.6%) and chest tightness (11.9%) were the most common symptoms in COVID-19 patients. As of February 28, 2020, of the 1663 patients included in this study, 26.0% were discharged, 10.2% were died, and 63.8% remained hospitalized. More than 1/3 of the patients had at least one comorbidity. Most (99.8%) patients had abnormal results Chest CT, and the most common manifestations of chest CT were local patchy shadowing (70.7%) and ground-glass opacity (44.8%). On admission, lymphocytopenia was present in 51.1% of the patients, mononucleosis in 26.6%, and erythrocytopenia in 61.3%. Most of the patients had increased levels of C-reactive protein (80.4%) and D-dimer (64.4%). Compared with non-severe patients, severe patients had more obvious abnormal laboratory results related to inflammation, coagulation disorders, liver and kidney damage (all P < 0.05). Older age (OR = 2.37, 95% CI: 1.47–3.83), leukocytosis (OR = 2.37, 95% CI: 1.47–3.83), and increased creatine kinase (OR = 2.37, 95% CI: 1.47–3.83) on admission were significantly associated with COVID-19 severity. Conclusion Timely medical treatment and clear diagnosis after the onset might be beneficial to control the condition of COVID-19. Severe patients were more likely to be to be elder, and tended to have higher proportion of comorbidities and more prominent laboratory abnormalities. Older age, leukocytosis, and increased creatine kinase might help clinicians to identify severe patients with COVID-19.

BackgroundThe ability of mesenchymal stem cells (MSCs) to migrate to the desired tissues or lesions is crucial for stem cell-based regenerative medicine and tissue engineering. Optimal therapeutics for promoting MSC migration are expected to become an effective means for tissue regeneration. Electromagnetic fields (EMF), as a noninvasive therapy, can cause a lot of biological changes in MSCs. However, whether EMF can promote MSC migration has not yet been reported.MethodsWe evaluated the effects of EMF on cell migration in human bone marrow-derived MSCs. With the use of Helmholtz coils and an EMF stimulator, 7.5, 15, 30, 50, and 70 Hz/1 mT EMF was generated. Additionally, we employed the l-type calcium channel blocker verapamil and the focal adhesion kinase (FAK) inhibitor PF-573228 to investigate the role of intracellular calcium content, cell adhesion proteins, and the Rho GTPase protein family (RhoA, Rac1, and Cdc42) in EMF-mediated MSC migration. Cell adhesion proteins (FAK, talin, and vinculin) were detected by Western blot analysis. The Rho GTPase protein family activities were assessed by G-LISA, and F-actin levels, which reflect actin cytoskeletal organization, were detected using immunofluorescence.ResultsAll the 7.5, 15, 30, 50, and 70 Hz/1 mT EMF promoted MSC migration. EMF increased MSC migration in an intracellular calcium-dependent manner. Notably, EMF-enhanced migration was mediated by FAK activation, which was critical for the formation of focal contacts, as evidenced by increased talin and vinculin expression. Moreover, RhoA, Rac1, and Cdc42 were activated by FAK to increase cytoskeletal organization, thus promoting cell contraction.ConclusionsEMF promoted MSC migration by increasing intracellular calcium and activating the FAK/Rho GTPase signaling pathways. This study provides insights into the mechanisms of MSC migration and will enable the rational design of targeted therapies to improve MSC engraftment.Electronic supplementary materialThe online version of this article (10.1186/s13287-018-0883-4) contains supplementary material, which is available to authorized users.

Cell penetrating peptides (CPPs) are a series of promising carriers for delivering exogenous DNA to living cells. Among them, the combination of the human immunodeficiency virus TAT protein (TAT) with the SV40 large T protein nuclear localization signal (NLS) to form NLS-TAT performs well. In the present study, we took advantage of this new carrier to deliver transforming growth factor-beta 3 (TGFβ3) genes. TGFβ3 was expressed by the pEGFP-N1 vector following transfection of rat precartilaginous stem cells (PSCs), which promoted hTGFβ3 protein self-expression. At 24, 48, 72, and 120 h after transfection, the expression levels of hTGFβ3 were found to be elevated as compared with the control. The expression of hTGFβ3 was found to mediate the chondrogenic effect of PSCs. Thus, we determined the expression of the chondrogenesis-related genes type II collagen, Sox 9, and aggrecan in PSCs at 24, 48, 72, and 120 h after transfection. We found that their transcription and translation was augmented, which indicated a trend of active chondrogenesis in the PSCs. Our results demonstrated that NLS-TAT had the ability to deliver exogenous DNA into rat PSCs and could be actively expressed. This process successfully promoted PSC chondrogenesis. Additionally, PSC, may represent a new type of stem cells, and thus show great potential in regenerative repair following cartilage injury.