scholarly journals Human Cytomegalovirus–Platelet Interaction Triggers Toll-Like Receptor 2–Dependent Proinflammatory and Proangiogenic Responses

2014 ◽  
Vol 34 (4) ◽  
pp. 801-809 ◽  
Author(s):  
Alice Assinger ◽  
Julia B. Kral ◽  
Koon C. Yaiw ◽  
Waltraud C. Schrottmaier ◽  
Ewa Kurzejamska ◽  
...  
Keyword(s):  
Growth Factor ◽  
Platelet Activation ◽  
Human Cytomegalovirus ◽  
Viral Reactivation ◽  
In Vivo Model ◽  
Vascular Endothelial ◽  
Toll Like Receptor ◽  
Wild Type ◽  
Tlr2 Expression ◽  
Activated Platelets

Objective— Human cytomegalovirus (HCMV) is a widespread pathogen that correlates with various clinical complications, including atherosclerosis. HCMV is released into the circulation during primary infection and periodic viral reactivation, allowing virus–platelet interactions. Platelets are important in the onset and development of atherosclerosis, but the consequences of platelet–HCMV interactions are unclear. Approach and Results— We studied the effects of HCMV–platelet interactions in blood from healthy donors using the purified clinical HCMV isolate VR1814. We demonstrated that HCMV bound to a Toll-like receptor (TLR) 2–positive platelet subpopulation, which resulted in signal transduction, degranulation, and release of proinflammatory CD40L and interleukin-1β and proangiogenic vascular endothelial–derived growth factor. In mice, murine CMV activated wild-type but not TLR2-deficient platelets. However, supernatant from murine CMV–stimulated wild-type platelets also activated TLR2-deficient platelets, indicating that activated platelets generated soluble mediators that triggered further platelet activation, independent of TLR2 expression. Inhibitor studies, using ADP receptor antagonists and apyrase, revealed that ADP release is important to trigger secondary platelet activation in response to HCMV. HCMV-activated platelets rapidly bound to and activated neutrophils, supporting their adhesion and transmigration through endothelial monolayers. In an in vivo model, murine CMV induced systemic upregulation of platelet–leukocyte aggregates and plasma vascular endothelial–derived growth factor in mice and showed a tendency to enhance neutrophil extravasation in a TLR2-dependent fashion. Conclusions— HCMV is a well-adapted pathogen that does not induce immediate thrombotic events. However, HCMV–platelet interactions lead to proinflammatory and proangiogenic responses, which exacerbate tissue damage and contribute to atherogenesis. Therefore, platelets might contribute to the effects of HCMV in accelerating atherosclerosis.

scholarly journals Adverse Adipose Phenotype and Hyperinsulinemia in Gravid Mice Deficient in Placental Growth Factor

Endocrinology ◽  
2008 ◽  
Vol 149 (5) ◽  
pp. 2176-2183 ◽  
Author(s):  
Bianca Hemmeryckx ◽  
Rita van Bree ◽  
Berthe Van Hoef ◽  
Lisbeth Vercruysse ◽  
H. Roger Lijnen ◽  
...  
Keyword(s):  
Growth Factor ◽  
Adrenergic Receptors ◽  
Growth Factor Receptor ◽  
Placental Growth Factor ◽  
Peroxisome Proliferator ◽  
Vascular Endothelial ◽  
Wild Type ◽  
Peroxisome Proliferator Activated Receptor ◽  
Adipocyte Hypertrophy ◽  
Endothelial Growth Factor

Pregnancy-induced metabolic changes are regulated by signals from an expanded adipose organ. Placental growth factor (PlGF), acting through vascular endothelial growth factor receptor-1, may be among those signals. There is a steep rise in circulating PlGF during normal pregnancy, which is repressed in gravidas who develop preeclampsia. PlGF-deficiency in mice impairs adipose vascularization and development. Here we studied young-adult PlGF-deficient (PlGF−/−) and wild-type mice on a high-fat diet in the nongravid state and at embryonic day (E) 13.5 or E18.5 of gestation. Litter size and weight were normal, but E18.5 placentas were smaller in PlGF−/− pregnancies. PlGF−/− mice showed altered intraadipose dynamics, with the following: 1) less blood vessels and fewer brown, uncoupling protein (UCP)-1-positive, adipocytes in white sc and perigonadal fat compartments and 2) white adipocyte hypertrophy. The mRNA expression of β3-adrenergic receptors, peroxisome proliferator-activated receptor-γ coactivator-1α, and UCP-1 was decreased accordingly. Moreover, PlGF−/− mice showed hyperinsulinemia. Pregnancy-associated changes were largely comparable in PlGF−/− and wild-type dams. They included expanded sc fat compartments and adipocyte hypertrophy, whereas adipose expression of key angiogenesis/adipogenesis (vascular endothelial growth factor receptor-1, peroxisome proliferator-activated receptor-γ2) and thermogenesis (β3-adrenergic receptors, peroxisome proliferator-activated receptor-γ coactivator-1α, and UCP-1) genes was down-regulated; circulating insulin levels gradually increased during pregnancy. In conclusion, reduced adipose vascularization in PlGF−/− mice impairs adaptive thermogenesis in favor of energy storage, thereby promoting insulin resistance and hyperinsulinemia. Pregnancy adds to these changes by PlGF-independent mechanisms. Disturbed intraadipose dynamics is a novel mechanism to explain metabolic changes in late pregnancy in general and preeclamptic pregnancy in particular.

scholarly journals Estrogen-Induced CCN1 Is Critical for Establishment of Endometriosis-Like Lesions in Mice

2014 ◽  
Vol 28 (12) ◽  
pp. 1934-1947 ◽  
Author(s):  
Yuechao Zhao ◽  
Quanxi Li ◽  
Benita S. Katzenellenbogen ◽  
Lester F. Lau ◽  
Robert N. Taylor ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Cell Proliferation ◽  
Growth Factor ◽  
Molecular Mechanisms ◽  
Tissue Growth ◽  
Endometrial Tissue ◽  
Vascular Endothelial ◽  
Wild Type ◽  
Factor C ◽  
Endothelial Growth Factor

Endometriosis is a prevalent gynecological disorder in which endometrial tissue proliferates in extrauterine sites, such as the peritoneal cavity, eventually giving rise to painful, invasive lesions. Dysregulated estradiol (E) signaling has been implicated in this condition. However, the molecular mechanisms that operate downstream of E in the ectopic endometrial tissue are unknown. To investigate these mechanisms, we used a mouse model of endometriosis. Endometrial tissue from donor mice was surgically transplanted on the peritoneal surface of immunocompetent syngeneic recipient mice, leading to the establishment of cystic endometriosis-like lesions. Our studies revealed that treatment with E led to an approximately 3-fold increase in the lesion size within a week of transplantation. E also caused a concomitant stimulation in the expression of connective tissue growth factor/Cyr61/Nov (CCN1), a secreted cysteine-rich matricellular protein, in the lesions. Interestingly, CCN1 is highly expressed in human ectopic endometriotic lesions. To address its role in endometriosis, endometrial tissue from Ccn1-null donor mice was transplanted in wild-type recipient mice. The resulting ectopic lesions were reduced up to 75% in size compared with wild-type lesions due to diminished cell proliferation and cyst formation. Notably, loss of CCN1 also disrupted the development of vascular networks in the ectopic lesions and reduced the expression of several angiogenic factors, such as vascular endothelial growth factor-A and vascular endothelial growth factor-C. These results suggest that CCN1, acting downstream of E, critically controls cell proliferation and neovascularization, which support the growth and survival of endometriotic tissue at ectopic sites. Blockade of CCN1 signaling during the early stages of lesion establishment may provide a therapeutic avenue to control endometriosis.

Angiogenesis and Tumor Growth Are Increased in Kininogen Deficient Mice

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 371-371
Author(s):  
Wan-Ming Zhang ◽  
Linda Hsi ◽  
Keith R. McCrae
Keyword(s):  
Growth Factor ◽  
Tumor Growth ◽  
Conflicts Of Interest ◽  
Vascular Endothelial Cell ◽  
Vascular Endothelial ◽  
Wild Type ◽  
Contact Phase ◽  
Tumor Implantation ◽  
Antiangiogenic Activity ◽  
Deficient Mice

Abstract Abstract 371 High molecular weight kininogen (HK) is an abundant plasma protein and member of the contact phase of coagulation that is involved in a number of important biological processes. We have previously reported that kallikrein-cleaved HK (HKa) induces rapid apoptosis of proliferating endothelial cells and inhibits angiogenesis. We have recently produced a kininogen deficient mouse by deleting the murine gene for kininogen that is expressed in liver, mKng1. These mice lack detectable kininogen, despite persistent expression of mRNA from the mKng2 gene, primarily expressed in kidney. To further determine the importance of kininogen in the regulation of angiogenesis, we assessed angiogenesis in mKng1−/− mice. These mice demonstrated increased angiogenesis in subcutaneously-implanted Matrigel plugs containing vascular endothelial cell growth factor (VEGF) or basic fibroblast growth factor (bFGF), compared to wild-type littermates. We also assessed the growth of B16F10 melanoma cells and Lewis lung carcinomas planted subcutaneously in mKng1−/− mice. In both cases, in particular with the B16F10 implants, tumor growth occurred substantially faster in the setting of kininogen deficiency (mean tumor volume of mKng1−/− mice 4820 ± 728 mm3 vs 1990 ± 412 mm3 in wild type mice; P = 0.003). Differences in growth rates were apparent approximately 8 days after tumor implantation, and were associated with increases in tumor microvascular density. Several reports suggest that the urokinase receptor (uPAR), which binds HKa, mediates its antiangiogenic activity. However, using Matrigel plug assays we observed that HKa inhibited angiogenesis equally well in wild type and uPAR−/− mice. These studies demonstrate that kininogen serves as an endogenous regulator of angiogenesis. Current studies are focused on better defining the mechanisms of this activity. Disclosures: No relevant conflicts of interest to declare.

P-Selectin and Platelet Clearance

Blood ◽  
1998 ◽  
Vol 92 (11) ◽  
pp. 4446-4452 ◽  
Author(s):  
Gaëtan Berger ◽  
Daqing W. Hartwell ◽  
Denisa D. Wagner
Keyword(s):  
Flow Cytometry ◽  
Endothelial Cells ◽  
Platelet Activation ◽  
Soluble Form ◽  
Wild Type ◽  
Adhesion Receptor ◽  
Activated Platelets ◽  
Deficient Mice

P-selectin is an adhesion receptor for leukocytes expressed by activated platelets and endothelial cells. To assess a possible role of P-selectin in platelet clearance, we adapted an in vivo biotinylation technique in mice. Wild-type and P-selectin–deficient mice were infused with N-hydroxysuccinimido biotin. The survival of biotinylated platelets was followed by flow cytometry after labeling with fluorescent streptavidin. Both wild-type and P-selectin–deficient platelets presented identical life spans of about 4.7 days, suggesting that P-selectin does not play a role in platelet turnover. When biotinylated platelets were isolated, activated with thrombin, and reinjected into mice, the rate of platelet clearance was unchanged. In contrast, storage of platelets at 4°C caused a significant reduction in their life span in vivo but again no significant differences were observed between the two genotypes. The infused thrombin-activated platelets rapidly lost their surface P-selectin in circulation, and this loss was accompanied by the simultaneous appearance of a 100-kD P-selectin fragment in the plasma. This observation suggests that the platelet membrane P-selectin was shed by cleavage. In conclusion, this study shows that P-selectin, despite its binding to leukocytes, does not mediate platelet clearance. However, the generation of a soluble form of P-selectin on platelet activation may have biological implications in modulating leukocyte recruitment or thrombus growth.

scholarly journals Vascular Endothelial Growth Factor D Is Dispensable for Development of the Lymphatic System

2005 ◽  
Vol 25 (6) ◽  
pp. 2441-2449 ◽  
Author(s):  
Megan E. Baldwin ◽  
Michael M. Halford ◽  
Sally Roufail ◽  
Richard A. Williams ◽  
Margaret L. Hibbs ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Growth Factor ◽  
Lymphatic Vessels ◽  
Growth Factor Receptor ◽  
Vascular Endothelial ◽  
Wild Type ◽  
Tissue Mass ◽  
And Function ◽  
Endothelial Growth Factor ◽  
Deficient Mice

ABSTRACT Vascular endothelial growth factor receptor 3 (Vegfr-3) is a tyrosine kinase that is expressed on the lymphatic endothelium and that signals for the growth of the lymphatic vessels (lymphangiogenesis). Vegf-d, a secreted glycoprotein, is one of two known activating ligands for Vegfr-3, the other being Vegf-c. Vegf-d stimulates lymphangiogenesis in tissues and tumors; however, its role in embryonic development was previously unknown. Here we report the generation and analysis of mutant mice deficient for Vegf-d. Vegf-d-deficient mice were healthy and fertile, had normal body mass, and displayed no pathologic changes consistent with a defect in lymphatic function. The lungs, sites of strong Vegf-d gene expression during embryogenesis in wild-type mice, were normal in Vegf-d-deficient mice with respect to tissue mass and morphology, except that the abundance of the lymphatics adjacent to bronchioles was slightly reduced. Dye uptake experiments indicated that large lymphatics under the skin were present in normal locations and were functional. Smaller dermal lymphatics were similar in number, location, and function to those in wild-type controls. The lack of a profound lymphatic phenotype in Vegf-d-deficient mice suggests that Vegf-d does not play a major role in lymphatic development or that Vegf-c or another, as-yet-unknown activating Vegfr-3 ligand can compensate for Vegf-d during development.

scholarly journals Human solCD39 inhibits injury-induced development of neointimal hyperplasia

2010 ◽  
Vol 103 (02) ◽  
pp. 426-435 ◽  
Author(s):  
Rosemary Kraemer ◽  
Hao Shen ◽  
Rita Upmacis ◽  
Aaron Marcus ◽  
Elgilda Musi ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Platelet Activation ◽  
Blood Platelets ◽  
Neointimal Hyperplasia ◽  
Endothelial Injury ◽  
Vascular Endothelial ◽  
Leukocyte Infiltration ◽  
Post Injury ◽  
Arterial Lumen ◽  
Activated Platelets

SummaryBlood platelets provide the initial response to vascular endothelial injury, becoming activated as they adhere to the injured site. Activated platelets recruit leukocytes, and initiate proliferation and migration of vascular smooth muscle cells (SMC) within the injured vessel wall, leading to development of neointimal hyperplasia. Endothelial CD39/NTPDase1 and recombinant solCD39 rapidly metabolise nucleotides, including stimulatory ADP released from activated platelets, thereby suppressing additional platelet reactivity. Using a murine model of vascular endothelial injury, we investigated whether circulating human solCD39 could reduce platelet activation and accumulation, thus abating leukocyte infiltration and neointimal formation following vascular damage. Intraperitoneally-administered solCD39 ADP -ase activity in plasma peaked 1 hour (h) post-injection, with an elimination half-life of 43 h. Accordingly, mice were administered solCD39 or saline 1 h prior to vessel injury, then either sacrificed 24 h post-injury or treated with solCD39 or saline (three times weekly) for an additional 18 days. Twenty-four hours post-injury, solCD39-treated mice displayed a reduction in platelet activation and recruitment, P-selectin expression, and leukocyte accumulation in the arterial lumen. Furthermore, repeated administration of solCD39 modulated the late stage of vascular injury by suppressing leukocyte deposition, macrophage infiltration and smooth muscle cell (SMC) proliferation/migration, resulting in abrogation of neointimal thickening. In contrast, injured femoral arteries of saline-injected mice exhibited massive platelet thrombus formation, marked P-selectin expression, and leukocyte infiltration. Pronounced neointimal growth with macrophage and SMC accretion was also observed (intimal-to-medial area ratio 1.56 ± 0.34 at 19 days). Thus, systemic administration of solCD39 profoundly affects injury-induced cellular responses, minimising platelet deposition and leukocyte recruitment, and suppressing neointimal hyperplasia.

Sign in / Sign up

Export Citation Format

Share Document