Project description:Development of spider veins is caused by the remodeling of veins located in the upper dermis and promoted by risk factors such as obesity or pregnancy that chronically increase venous pressure. We have repeatedly shown that the pressure-induced increase in biomechanical wall stress is sufficient to evoke the formation of enlarged corkscrew-like superficial veins in mice. Subsequent experimental approaches revealed that interference with endothelial- and/or smooth muscle cell activation counteracts this remodeling process. Here, we investigate whether the herbal agent glycyrrhetinic acid (GA) is a suitable candidate for that purpose given its anti-proliferative as well as anti-oxidative properties. While basic abilities of cultured venous smooth muscle cells (SMCs) such as migration and proliferation were not influenced by GA, it inhibited proliferation but not angiogenic sprouting of human venous endothelial cells (ECs). Further analyses of biomechanically stimulated ECs revealed that GA inhibits the DNA binding capacity of the mechanosensitive transcription factor activator protein-1 (AP-1) which, however, had only a minor impact on the endothelial transcriptome. Nevertheless, by decreasing gelatinase activity in ECs or mouse veins exposed to biomechanical stress, GA diminished a crucial cellular response in the context of venous remodeling. In line with the observed inhibitory effects, local transdermal application of GA attenuated pressure-mediated enlargement of veins in the mouse auricle. In summary, our data identifies GA as an inhibitor of EC proliferation, gelatinase activity and venous remodeling. It may thus have the capacity to attenuate spider vein formation and remodeling in humans.
Project description:Development of spider veins is caused by the remodeling of veins located in the upper dermis and promoted by risk factors such as obesity or pregnancy that chronically increase venous pressure. We have repeatedly shown that the pressure-induced increase in biomechanical wall stress is sufficient to evoke the formation of enlarged corkscrew-like superficial veins in mice. Subsequent experimental approaches revealed that interference with endothelial- and/or smooth muscle cell (SMC) activation counteracts this remodeling process. Here, we investigate whether the herbal agent glycyrrhetinic acid (GA) is a suitable candidate for that purpose given its anti-proliferative as well as anti-oxidative properties. While basic abilities of cultured venous SMCs such as migration and proliferation were not influenced by GA, it inhibited proliferation but not angiogenic sprouting of human venous endothelial cells (ECs). Further analyses of biomechanically stimulated ECs revealed that GA inhibits the DNA binding capacity of the mechanosensitive transcription factor activator protein-1 (AP-1) which, however, had only a minor impact on the endothelial transcriptome. Nevertheless, by decreasing gelatinase activity in ECs or mouse veins exposed to biomechanical stress, GA diminished a crucial cellular response in the context of venous remodeling. In line with the observed inhibitory effects, local transdermal application of GA attenuated pressure-mediated enlargement of veins in the mouse auricle. In summary, our data identifies GA as an inhibitor of EC proliferation, gelatinase activity and venous remodeling. It may thus have the capacity to attenuate spider vein formation and remodeling in humans.
Project description:Two matched groups of Heart Failure with reduced ejection fraction patients with no peripheral venous congestion were studied: with recent prior heart failure hospitalization vs. without recent heart failure hospitalization. Peripheral venous congestion was modeled by inflating a cuff around the dominant arm, targeting an ~30mmHg increase in venous pressure (venous stress test). Blood and endothelial cells were sampled before and after 90 minutes of venous stress test.
Project description:BACKGROUND: As evidenced by epidemiological and etiological studies, the development of varicose veins is driven by risk-factors which support the development of venous hypertension and thus chronically augment circumferential stress of the venous wall (e.g. dysfunctional venous valves, pregnancy or obesity). We have previously verified the relevance of this biomechanical stimulus for the activation of venous endothelial as well as smooth muscle cells and the subsequent detrimental structural remodeling of the vein wall in experimental mouse models. METHODS: Here, transcriptome analyses revealed an increase in the expression of cyclooxygenase 2 (COX-2) in human venous endothelial cells upon exposure to biomechanical stress. Subsequently, we investigated the impact of diclofenac – a cyclooxygenase inhibitor – on responses of isolated mouse veins to augmented wall stress in vitro and on varicose-like venous remodeling in vivo. RESULTS: Diclofenac treatment decreased COX-2 protein abundance in mouse veins but had no significant impact on the expression of corresponding transcripts. Short-term exposure to elevated pressure levels stimulated the activity of matrix-metalloproteinase-2 (MMP-2) and mitogen activated protein kinases ERK1/2. Diclofenac decreased the level of activated MMP-2 and ERK1/2 in pressure-exposed mouse veins. Varikose-like remodeling of veins in the mouse auricle was significantly inhibited by transdermal application of diclofenac-containing phospholipid-micelles. This effect was associated with decreased COX-2 and MMP-2 abundance as well as cell proliferation. CONCLUSION: The cyclooxygenase inhibitor diclofenac interferes with short term activation of MAP-kinases and matrix-metalloproteinases in cells of the wall stress-exposed venous wall while attenuating venous remodeling in vivo. Thus, nonsteroidal anti-inflammatory drugs may be suitable to interfere with processes promoting the progression of varicose vein development and biomechanical activation of venous cells.
Project description:Background: Venous hypertension is often present in advanced and in acute decompensated heart failure (HF). However, it is unclear whether high intravenous pressure can cause alterations in homeostasis by promoting inflammation and endothelial cell (EC) activation. We used an experimental model of acute, local venous hypertension to study the changes in circulating inflammatory mediators and EC phenotype that occur in response to biomechanical stress. Methods and Results: Twenty-four healthy subjects (14 men, age 35±2 years) were studied. Venous arm pressure was increased to ~30 mmHg above baseline level by inflating a tourniquet cuff around the dominant arm (test arm). Blood and endothelial cells (ECs) were sampled from test and control arm (lacking an inflated cuff) before and after 75 minutes of venous hypertension, using angiocatheters and endovascular wires. Magnetic beads coated with EC specific antibodies were used for EC separation; amplified mRNA was analyzed by Affymetrix HG-U133 2.0 Microarray. Plasma endothelin-1 (ET-1), interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM-1) and chemokine (C-X-C motif) ligand 2 (CXCL2) were significantly increased in the congested arm. 5,332 probe sets were differentially expressed in venous ECs before vs. after testing. Among the 143 probe sets that exhibited a significant absolute fold change >2, we identified several inflammatory mediators including ET-1, VCAM-1, and CXCL2. Conclusions: Acute experimental venous hypertension is sufficient to cause local increase in circulating inflammatory mediators and to activate venous ECs in healthy human subjects. Additional work is needed to determine the effect of venous hypertension in patients with established HF. 24 samples were analyzed from 12 patients. Each patient contributed 2 samples (1 prior to intervention and 1 after intervention). The pre-intervention sample serves as the control.
Project description:Background: Venous hypertension is often present in advanced and in acute decompensated heart failure (HF). However, it is unclear whether high intravenous pressure can cause alterations in homeostasis by promoting inflammation and endothelial cell (EC) activation. We used an experimental model of acute, local venous hypertension to study the changes in circulating inflammatory mediators and EC phenotype that occur in response to biomechanical stress. Methods and Results: Twenty-four healthy subjects (14 men, age 35±2 years) were studied. Venous arm pressure was increased to ~30 mmHg above baseline level by inflating a tourniquet cuff around the dominant arm (test arm). Blood and endothelial cells (ECs) were sampled from test and control arm (lacking an inflated cuff) before and after 75 minutes of venous hypertension, using angiocatheters and endovascular wires. Magnetic beads coated with EC specific antibodies were used for EC separation; amplified mRNA was analyzed by Affymetrix HG-U133 2.0 Microarray. Plasma endothelin-1 (ET-1), interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM-1) and chemokine (C-X-C motif) ligand 2 (CXCL2) were significantly increased in the congested arm. 5,332 probe sets were differentially expressed in venous ECs before vs. after testing. Among the 143 probe sets that exhibited a significant absolute fold change >2, we identified several inflammatory mediators including ET-1, VCAM-1, and CXCL2. Conclusions: Acute experimental venous hypertension is sufficient to cause local increase in circulating inflammatory mediators and to activate venous ECs in healthy human subjects. Additional work is needed to determine the effect of venous hypertension in patients with established HF.
Project description:Following parenchymal loss, the liver regenerates restoring normal mass and metabolic function. Prevailing theories on triggering events leading to regeneration include humoral, metabolic and flow-mediated mechanisms, the latter emphasizing the importance of shear stress mediated nitric oxide (NO) regulation. We aimed to investigate whether the grade of resection and hence the portal venous pressure and sinusoidal shear stress increase, would be reflected in the gene expression profiles in the liver remnant by employing a global porcine cDNA microarray chip with approximately 23 000 genes represented. Six pig livers were resected with 62% (Low Portal Pressure Resection, LPPR) and 75% (High Portal Pressure Resection) resulting in a portal venous pressure increase from a baseline of 6.1 mmHg to 8.2 and 12 mmHg respectively. By sampling consecutive biopsies from the liver remnants we found differentially expressed genes in the HPPR group to have functions related primarily to apoptosis, nitric oxide metabolism and oxidative stress, whereas differentially expressed genes in the LPPR group potentially regulate the cell cycle. Common to both groups was the upregulation of genes regulating inflammation, transport, cell proliferation and development and protein metabolism. Also common to both groups was both up- and downregulation of genes regulating cell-cell signaling, signal transduction, cell adhesion and translation. Genes regulating the metabolism of lipids, hormones, amines, and alcohol were downregulated in both groups. Conclusions: The genetic regenerative response in the liver remnant to varies according to the level of resection. Keywords: time course, treatment comparison Three pigs underwent a 62% liver resection (low-pressure resection, LPR) and three underwent a 75% resection (high-pressure resection, HPR). Biopsies from the liver remnant were taken from all animals at time points 1, 30, 90, minutes and 3, 4 and 6 hours after resection. Expression profiling was conducted by hybridising each sample against a common reference, consisting of liver RNA from an unrelated animal.
Project description:Repair of the pulmonary vascular bed and the origin of new vasculature remains underexplored despite the critical necessity to meet oxygen demands after injury. Given their critical role in angiogenesis in other settings, we investigated the role of venous endothelial cells in endothelial regeneration after adult lung injury. Using single cell transcriptomics, we identified the norepinephrine transporter Slc6a2 as a marker of pulmonary venous endothelial cells and targeted that locus to generate a venous-specific, inducible Cre mouse line. Contributions of the venous endothelial cells to angiogenesis were examined during postnatal development, adult viral injury, and adult hyperoxia injury. Remarkably, we observed that venous endothelial cells proliferate into the adjacent capillary bed upon influenza injury and hyperoxia injury, but not during normal postnatal development. Imaging analysis demonstrated that venous endothelial cells exhibit the ability to proliferate and differentiate into general capillary and CAR4 expressing aerocyte capillary endothelial cells after infection, thus contributing to repair of the capillary plexus vital for gas exchange. Single cell transcriptomic analysis of Slc6a2 lineage traced cells confirmed these observations, with progeny exhibiting significant loss of venous identity and gain of capillary marker expression upon injury resolution. Our studies thus establish that venous endothelial cells exhibit demonstrable progenitor capacity upon respiratory viral injury and sterile injury, contributing to repair of the alveolar capillary bed responsible for pulmonary function.
Project description:Formation and maturation of a functional blood vascular system is required for the development and maintenance of all tissues in the body. During the process of blood vessel development, primordial endothelial cells are formed and become specified toward arterial or venous fates to generate a circulatory network that provides nutrients and oxygen to, and removes metabolic waste from, all tissues. Specification of arterial and venous endothelial cells occurs in conjunction with suppression of endothelial cell cycle progression, and endothelial cell hyperproliferation is associated with potentially lethal arterial-venous malformations. However, the mechanistic role that cell cycle state plays in arterial-venous specification is unknown. Herein, studying vascular development in Cdh5-CreERT2;R26FUCCI2aR reporter mice, we find that venous and arterial endothelial cells exhibit a propensity for different cell cycle states during development and in adulthood. That is, venous endothelial cells are predominantly FUCCI-Negative, while arterial endothelial cells are enriched for the FUCCI-Red reporter. Single cell RNA sequencing analysis of developing retinal endothelial cells reveals that venous endothelial cells are enriched for the FUCCI-Negative state and BMP signaling, while arterial endothelial cells are enriched for the FUCCI-Red state and TGF-b signaling. Further transcriptional analyses and live imaging of cultured endothelial cells expressing the FUCCI reporter show that reporter-negative corresponds to an early G1 state and reporter-red corresponds to late G1 state. We find the early G1 state is essential for BMP4-induced venous gene expression, whereas late G1 state is essential for TGF-b1-induced arterial gene expression. In a mouse model of endothelial cell hyperproliferation and disrupted arterial-venous specification, pharmacological inhibition of endothelial cell cycle prevents the vascular defects. Collectively, our results show that endothelial cell cycle control plays a key role in arterial-venous network formation, and distinct cell cycle states provide distinct windows of opportunity for the molecular induction of arterial vs. venous specification.