GDF-15 is abundantly expressed in plexiform lesions in patients with pulmonary arterial hypertension and affects proliferation and apoptosis of pulmonary endothelial cells

<p>Abstract</p> <p>Background</p> <p>Growth-differentiation factor-15 (GDF-15) is a stress-responsive, transforming growth factor-β-related cytokine, which has recently been reported to be elevated in serum of patients with idiopathic pulmonary arterial hypertension (IPAH). The aim of the study was to examine the expression and biological roles of GDF-15 in the lung of patients with pulmonary arterial hypertension (PAH).</p> <p>Methods</p> <p>GDF-15 expression in normal lungs and lung specimens of PAH patients were studied by real-time RT-PCR and immunohistochemistry. Using laser-assisted micro-dissection, GDF-15 expression was further analyzed within vascular compartments of PAH lungs. To elucidate the role of GDF-15 on endothelial cells, human pulmonary microvascular endothelial cells (HPMEC) were exposed to hypoxia and laminar shear stress. The effects of GDF-15 on the proliferation and cell death of HPMEC were studied using recombinant GDF-15 protein.</p> <p>Results</p> <p>GDF-15 expression was found to be increased in lung specimens from PAH patients, com-pared to normal lungs. GDF-15 was abundantly expressed in pulmonary vascular endothelial cells with a strong signal in the core of plexiform lesions. HPMEC responded with marked upregulation of GDF-15 to hypoxia and laminar shear stress. Apoptotic cell death of HPMEC was diminished, whereas HPMEC proliferation was either increased or decreased depending of the concentration of recombinant GDF-15 protein.</p> <p>Conclusions</p> <p>GDF-15 expression is increased in PAH lungs and appears predominantly located in vascular endothelial cells. The expression pattern as well as the observed effects on proliferation and apoptosis of pulmonary endothelial cells suggest a role of GDF-15 in the homeostasis of endothelial cells in PAH patients.</p

Vascular Targeted Agents for the Treatment of Angiosarcoma

Background: Angiogenesis is the process of new blood vessel formation, and is regulated by angiogenic growth factors including vascular endothelial growth factor (VEGF). Angiosarcomas are rare, aggressive vascular tumours. Studies were performed to investigate the expression of angiogenic growth factors in angiosarcoma, and to assess vascular targeted agents for the treatment of angiosarcoma. Methods: In vitro studies compared two human cutaneous angiosarcoma cell lines (ASM and ISO-HAS) with human dermal microvascular endothelial cells (HuDMECs). The cell lines were compared in functional assays, including cell viability, cell differentiaiton and cell migration assays, and protein expression profiled using antibody arrays. Cell responses to vascular targeted agents were compared, including response to bevacizumab an anti-VEGF antibody, axitinib a VEGF receptor (VEGFR) tyrosine kinase inhibitor, selumetinib a MEK inhibitor, and DMXAA a vascular disrupting agent. Immunohistochemistry studies measured the expression of angiogenic growth factors in angiosarcoma tumour specimens using benign vascular lesions for comparison, and assessed canine angiosarcoma as a model of human angiosarcoma. Results: ASM and ISO-HAS demonstrated accelerated growth kinetics, chaotic tubule formation, and increased cell migration compared to HuDMECs. ASM and ISO-HAS expressed significantly increased VEGF compared to HuDMECs. Only minor responses were observed to VEGF targeted agents in functional assays despite western blot studies that showed target inhibition of VEGFR2 phosphorylation,. Striking responses were seen however to selumetinib and DMXAA. Immunohistochemistry studies demonstrated benign and malignant vascular tumours expressed a range of pro-angiogenic growth factors, however analysis did not distinguish malignant from benign vascular tumours. The morphology of canine angiosarcoma was similar to human angiosarcoma. VEGF and VEGFR2 expression was significantly increased in canine angiosarcoma compared to benign vascular lesions. Conclusion: These studies predict limited in vivo angiosarcoma tumour response to VEGF targeted agents. Selumetinib and DMXAA are suggested for further study. Canine angiosarcomas represent a potential model of human angiosarcoma to be explored in future studies

Nipah Virus Uses Leukocytes for Efficient Dissemination within a Host ▿

Nipah virus (NiV) is a recently emerged zoonotic paramyxovirus whose natural reservoirs are several species of Pteropus fruit bats. NiV provokes a widespread vasculitis often associated with severe encephalitis, with up to 75% mortality in humans. We have analyzed the pathogenesis of NiV infection, using human leukocyte cultures and the hamster animal model, which closely reproduces human NiV infection. We report that human lymphocytes and monocytes are not permissive for NiV and a low level of virus replication is detected only in dendritic cells. Interestingly, despite the absence of infection, lymphocytes could efficiently bind NiV and transfer infection to endothelial and Vero cells. This lymphocyte-mediated transinfection was inhibited after proteolytic digestion and neutralization by NiV-specific antibodies, suggesting that cells could transfer infectious virus to other permissive cells without the requirement for NiV internalization. In NiV-infected hamsters, leukocytes captured and carried NiV after intraperitoneal infection without themselves being productively infected. Such NiV-loaded mononuclear leukocytes transfer lethal NiV infection into naïve animals, demonstrating efficient virus transinfection in vivo. Altogether, these results reveal a remarkable capacity of NiV to hijack leukocytes as vehicles to transinfect host cells and spread the virus throughout the organism. This mode of virus transmission represents a rapid and potent method of NiV dissemination, which may contribute to its high pathogenicity

Biofunctional nanofibrous substrate comprising immobilized antibodies and selective binding of autologous growth factors

The immobilization of biomolecules at the surface of different biomedical devices has attracted enormous interest in order to enhance their biological functionality at the cellular level. This work aims to develop a biofunctional polymeric substrate capable of selectively binding growth factors (GFs) of interest from a pool of proteins present in a biological fluid: platelet lysate (PL). To achieve this goal, the surface of electrospun PCL nanofibers needs to be activated and functionalized to be able to insert chemical groups for the immobilization of antibodies. After determining the maximum immobilization capacity of each antibody, TGF-β1 (12 μg mL(-1)), bFGF (8 μg mL(-1)), and VEGF (4 μg mL(-1)), the next step was to confirm their bioavailability using recombinant proteins. The binding efficiency of PL-derived GFs was of 84-87% for TGF-β1, 55-64% for bFGF, and 50-59% for VEGF. Cellular assays confirmed the biological activity of the bound VEGF (both recombinant and PL-derived). Multiple antibodies (i.e., bFGF and VEGF) were also immobilized over the same structure in a mixed or side-by-side fashion. Using both autologous biological fluids and cells, it is possible to use this platform to implement very effective and personalized therapies that can be tailored to specific medical conditions.The authors would like to thank the Maxbone (PTDC/SAU-ENB/115179/2009/FCOMP-01-0124-FEDER-015729) and Osteography (PTDC/EME-MFE/2008) projects as well as QREN (project "RLI-ABMR-NORTE-01-0124-FEDER-000016" cofinanced by the North Portugal Regional Operational Programme (ON.2, 0 Novo Norte) under the NSRF through the ERDF) for financing this research work