Atherosclerosis is considered both a metabolic and inflammatory disease; however, the specific tissue and signaling molecules that instigate and propagate this disease remain unclear. The liver is a central site of inflammation and lipid metabolism that is critical for atherosclerosis, and JAK2 is a key mediator of inflammation and, more recently, of hepatic lipid metabolism. However, precise effects of hepatic Jak2 on atherosclerosis remain unknown. We show here that hepatic Jak2 deficiency in atherosclerosis-prone mouse models exhibited accelerated atherosclerosis with increased plaque macrophages and decreased plaque smooth muscle cell content. JAK2’s essential role in growth hormone signalling in liver that resulted in reduced IGF-1 with hepatic Jak2 deficiency played a causal role in exacerbating atherosclerosis. As such, restoring IGF-1 either pharmacologically or genetically attenuated atherosclerotic burden. Together, our data show hepatic Jak2 to play a protective role in atherogenesis through actions mediated by circulating IGF-1 and, to our knowledge, provide a novel liver-centric mechanism in atheroprotection.
Tharini Sivasubramaniyam, Stephanie A. Schroer, Angela Li, Cynthia T. Luk, Sally Yu Shi, Rickvinder Besla, David W. Dodington, Adam H. Metherel, Alex P. Kitson, Jara J. Brunt, Joshua Lopes, Kay-Uwe Wagner, Richard P. Bazinet, Michelle P. Bendeck, Clinton S. Robbins, Minna Woo
BACKGROUND. Cannabidiol (CBD) is a nonpsychoactive phytocannabinoid used in multiple sclerosis and intractable epilepsies. Preclinical studies show CBD has numerous cardiovascular benefits, including a reduced blood pressure (BP) response to stress. The aim of this study was to investigate if CBD reduces BP in humans. METHODS. Nine healthy male volunteers were given 600 mg of CBD or placebo in a randomized, placebo-controlled, double-blind, crossover study. Cardiovascular parameters were monitored using a finometer and laser Doppler. RESULTS. CBD reduced resting systolic BP (–6 mmHg; P < 0.05) and stroke volume (–8 ml; P < 0.05), with increased heart rate (HR) and maintained cardiac output. Subjects who had taken CBD had lower BP (–5 mmHg; P < 0.05, especially before and after stress), increased HR (+10 bpm; P < 0.01), decreased stroke volume (–13 ml; P < 0.01), and a blunted forearm skin blood flow response to isometric exercise. In response to cold stress, subjects who had taken CBD had blunted BP (–6 mmHg; P < 0.01) and increased HR (+7 bpm; P < 0.05), with lower total peripheral resistance. CONCLUSIONS. This data shows that acute administration of CBD reduces resting BP and the BP increase to stress in humans, associated with increased HR. These hemodynamic changes should be considered for people taking CBD. Further research is required to establish whether CBD has a role in the treatment of cardiovascular disorders.
Khalid A. Jadoon, Garry D. Tan, Saoirse E. O’Sullivan
Lymphatic endothelium serves as a barrier to control fluid balance and immune cell trafficking to maintain tissue homeostasis. Long-term alteration of lymphatic vasculature promotes edema and fibrosis, which is an aggravating factor in the onset of cardiovascular diseases such as myocardial infarction. Apelin is a bioactive peptide that plays a central role in angiogenesis and cardiac contractility. Despite an established role of apelin in lymphangiogenesis, little is known about its function in the cardiac lymphatic endothelium. Here, we show that apelin and its receptor APJ were exclusively expressed on newly formed lymphatic vasculature in a pathological model of myocardial infarction. Using an apelin-knockout mouse model, we identified morphological and functional defects in lymphatic vasculature associated with a proinflammatory status. Surprisingly, apelin deficiency increased the expression of lymphangiogenic growth factors VEGF-C and VEGF-D and exacerbated lymphangiogenesis after myocardial infarction. Conversely, the overexpression of apelin in ischemic heart was sufficient to restore a functional lymphatic vasculature and to reduce matrix remodeling and inflammation. In vitro, the expression of apelin prevented the alteration of cellular junctions in lymphatic endothelial cells induced by hypoxia. In addition, we demonstrated that apelin controls the secretion of the lipid mediator sphingosine-1-phosphate in lymphatic endothelial cells by regulating the level of expression of sphingosine kinase 2 and the transporter SPNS2. Taken together, our results show that apelin plays a key role in lymphatic vessel maturation and stability in pathological settings. Thus, apelin may represent a novel candidate to prevent pathological lymphatic remodeling in diseases.
Florence Tatin, Edith Renaud-Gabardos, Anne-Claire Godet, Fransky Hantelys, Francoise Pujol, Florent Morfoisse, Denis Calise, Fanny Viars, Philippe Valet, Bernard Masri, Anne-Catherine Prats, Barbara Garmy-Susini
Using transcriptional profiling of platelets from patients presenting with acute myocardial infarction, we identified myeloid-related protein-14 (MRP-14, also known as S100A9) as an acute myocardial infarction gene and reported that platelet MRP-14 binding to platelet CD36 regulates arterial thrombosis. However, whether MRP-14 plays a role in venous thrombosis is unknown. We subjected WT and Mrp-14–deficient (Mrp-14-/-) mice to experimental models of deep vein thrombosis (DVT) by stasis ligation or partial flow restriction (stenosis) of the inferior vena cava. Thrombus weight in response to stasis ligation or stenosis was reduced significantly in Mrp-14-/- mice compared with WT mice. The adoptive transfer of WT neutrophils or platelets, or the infusion of recombinant MRP-8/14, into Mrp-14-/- mice rescued the venous thrombosis defect in Mrp-14-/- mice, indicating that neutrophil- and platelet-derived MRP-14 directly regulate venous thrombogenesis. Stimulation of neutrophils with MRP-14 induced neutrophil extracellular trap (NET) formation, and NETs were reduced in venous thrombi harvested from Mrp-14-/- mice and in Mrp-14-/- neutrophils stimulated with ionomycin. Given prior evidence that MRP-14 also regulates arterial thrombosis, but not hemostasis (i.e., reduced bleeding risk), MRP-14 appears to be a particularly attractive molecular target for treating thrombotic cardiovascular diseases, including myocardial infarction, stroke, and venous thromboembolism.
Yunmei Wang, Huiyun Gao, Chase W. Kessinger, Alvin Schmaier, Farouc A. Jaffer, Daniel I. Simon
Mechanisms of atherogenesis have been studied extensively in genetically engineered mice with disturbed cholesterol metabolism such as those lacking either the LDL receptor (
Srinivas D. Sithu, Marina V. Malovichko, Krista A. Riggs, Nalinie S. Wickramasinghe, Millicent G. Winner, Abhinav Agarwal, Rihab E. Hamed-Berair, Anuradha Kalani, Daniel W. Riggs, Aruni Bhatnagar, Sanjay Srivastava
Non–transferrin-bound iron (NTBI) and free hemoglobin (Hb) accumulate in circulation following stored RBC transfusions. This study investigated transfusion, vascular disease, and mortality in guinea pigs after stored RBC transfusion alone and following cotransfusion with apo-transferrin (apo-Tf) and haptoglobin (Hp). The effects of RBC exchange transfusion dose (1, 3, and 9 units), storage period (14 days), and mortality were evaluated in guinea pigs with a vascular disease phenotype. Seven-day mortality and the interaction between iron and Hb as cocontributors to adverse outcome were studied. Concentrations of iron and free Hb were greatest after transfusion with 9 units of stored RBCs compared with fresh RBCs or stored RBCs at 1- and 3-unit volumes. Nine units of stored RBCs led to mortality in vascular diseased animals, but not normal animals. One and 3 units of stored RBCs did not cause a mortality effect, suggesting the concomitant relevance of NTBI and Hb on outcome. Cotransfusion with apo-Tf or Hp restored survival to 100% following 9-unit RBC transfusions in vascular diseased animals. Our data suggest that increases in plasma NTBI and Hb contribute to vascular disease–associated mortality through iron-enhanced Hb oxidation and enhanced tissue injury.
Jin Hyen Baek, Ayla Yalamanoglu, Yamei Gao, Ricardo Guenster, Donat R. Spahn, Dominik J. Schaer, Paul W. Buehler
Antibody-secreting cells are generated in regional lymphoid tissues and traffic as plasmablasts (PBs) via lymph and blood to target sites for local immunity. We used multiparameter flow cytometry to define PB trafficking programs (TPs, combinations of adhesion molecules and chemoattractant receptors) and their imprinting in patients in response to localized infection or immune insults. TPs enriched after infection or autoimmune inflammation of mucosae correlate with sites of immune response or symptoms, with different TPs imprinted during small intestinal, colon, throat, and upper respiratory immune challenge. PBs induced after intramuscular or intradermal influenza vaccination, including flu-specific antibody–secreting cells, display TPs characterized by the lack of mucosal homing receptors. PBs of healthy donors display diverse mucosa-associated TPs, consistent with homeostatic immune activity. Identification of TP signatures of PBs may facilitate noninvasive monitoring of organ-specific immune responses.
Yekyung Seong, Nicole H. Lazarus, Lusijah Sutherland, Aida Habtezion, Tzvia Abramson, Xiao-Song He, Harry B. Greenberg, Eugene C. Butcher
Impaired PPARγ activity in endothelial cells causes oxidative stress and endothelial dysfunction which causes a predisposition to hypertension, but the identity of key PPARγ target genes that protect the endothelium remain unclear. Retinol-binding protein 7 (RBP7) is a PPARγ target gene that is essentially endothelium specific. Whereas RBP7-deficient mice exhibit normal endothelial function at baseline, they exhibit severe endothelial dysfunction in response to cardiovascular stressors, including high-fat diet and subpressor angiotensin II. Endothelial dysfunction was not due to differences in weight gain, impaired glucose homeostasis, or hepatosteatosis, but occurred through an oxidative stress–dependent mechanism which can be rescued by scavengers of superoxide. RNA sequencing revealed that RBP7 was required to mediate induction of a subset of PPARγ target genes by rosiglitazone in the endothelium including adiponectin. Adiponectin was selectively induced in the endothelium of control mice by high-fat diet and rosiglitazone, whereas RBP7 deficiency abolished this induction. Adiponectin inhibition caused endothelial dysfunction in control vessels, whereas adiponectin treatment of RBP7-deficient vessels improved endothelium-dependent relaxation and reduced oxidative stress. We conclude that RBP7 is required to mediate the protective effects of PPARγ in the endothelium through adiponectin, and RBP7 is an endothelium-specific PPARγ target and regulator of PPARγ activity.
Chunyan Hu, Henry L. Keen, Ko-Ting Lu, Xuebo Liu, Jing Wu, Deborah R. Davis, Stella-Rita C. Ibeawuchi, Silke Vogel, Frederick W. Quelle, Curt D. Sigmund
Occurrence of transient ischemic attacks (TIA) and cerebral strokes is a recognized risk associated with cocaine abuse. Here, we use a rodent model along with optical imaging to study cocaine-induced TIA and the associated dynamic changes in cerebral blood flow velocity (CBFv) and cerebrovasculature. We show that chronic cocaine exposure in mice resulted in marked cortical hypoperfusion, in significant arterial and venous vasoconstriction, and in a sensitized vascular response to an acute cocaine injection. Starting after 10 days of exposure, an acute cocaine challenge to these mice resulted in a TIA, which presented as hemiparalysis and was associated with an abrupt exacerbation of CBFv. The severity of the TIA correlated with the decreases in cortical CBFv such that the greater the decreases in flow, the longer the TIA duration. The severity of TIA peaked around 17–22 days of cocaine exposure and decreased thereafter in parallel to a reorganization of CBFv from superficial to deep cortical layers, along with an increase in vessel density into these layers. Here, we document for the first time to our knowledge evidence of a TIA in an animal model of chronic cocaine exposure that was associated with profound decreases in CBFv, and we revealed that while the severity of the TIA initially increased with repeated exposures, it subsequently improved in parallel to an increase in the vessel density. This suggests that strategies to accelerate cerebrovascular recovery might be therapeutically beneficial in cocaine abusers.
Jiang You, Nora D. Volkow, Kicheon Park, Quijia Zhang, Kevin Clare, Congwu Du, Yingtian Pan
Pulmonary hypertension (PH) is a multifaceted vascular disease where development and severity are determined by both genetic and environmental factors. Over the past decade, there has been an acceleration of the discovery of molecular effectors that mediate PH pathogenesis, including large numbers of microRNA molecules that are expressed in pulmonary vascular cell types and exert system-wide regulatory functions in all aspects of vascular health and disease. Due to the inherent pleiotropy, overlap, and redundancy of these molecules, it has been challenging to define their integrated effects on overall disease manifestation. In this review, we summarize our current understanding of the roles of microRNAs in PH with an emphasis on potential methods to discern the hierarchical motifs governing their multifunctional and interconnected activities. Deciphering this higher order of regulatory structure will be crucial for overcoming the challenges of developing these molecules as biomarkers or therapeutic targets, in isolation or combination.
Vinny Negi, Stephen Y. Chan
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