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Inferior vena cava (IVC) stenting may provide benefit to patients with symptomatic obstruction; however, there are no devices currently licensed for use in the IVC and systematic reviews on the topic are lacking. The aim of this study was to carry out a systematic review of the literature and meta-analysis to investigate the safety and efficacy of IVC stenting in all adult patient groups.The Medline and Embase databases were searched for studies reporting outcomes for safety and effectiveness of IVC stenting for any indication in series of 10 or more patients.A systematic review of the literature was carried out according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.Thirty-three studies were included describing 1 575 patients. Indications for stenting were malignant IVC syndrome (229 patients), thrombotic disease (807 patients), Budd-Chiari syndrome (501 patients), and IVC stenosis post liver transplantation (47 patients). The male:female ratio was 2:1 and the median age ranged from 30 to 61 years. The studies included were not suitable for formal meta-analysis as 30/33 were single centre retrospective studies with no control groups and there was considerable inconsistency in outcome reporting. There was significant risk of bias in 94% of studies. Median reported technical success was 100% (range 78 - 100%), primary patency was 75% (38 - 98%), and secondary patency was 91.5% (77 - 100%). Major complications were pulmonary embolism (three cases), stent migration (12 cases), and major bleeding (15 cases), and there were three deaths in the immediate post-operative period. Most studies reported improvement in clinical symptoms but formal reporting tools were not used consistently.The evidence base for IVC stenting consists of predominantly single centre, retrospective, observational studies that have a high risk of bias. Nonetheless the procedure appears safe with few major adverse events, and studies that reported clinical outcomes demonstrate improvement in symptoms and quality of life. Randomised controlled trials and prospective registry based studies with larger patient numbers and standardised outcome are required to improve the evidence base for this procedure.

This paper describes the synthesis, solution-phase biophysical studies, and X-ray crystallographic structures of hexamers formed by macrocyclic β-hairpin peptides derived from the central and C-terminal regions of Aβ, which bear “tails” derived from the N-terminus of Aβ. Soluble oligomers of the β-amyloid peptide, Aβ, are thought to be the synaptotoxic species responsible for neurodegeneration in Alzheimer’s disease. Over the last 20 years, evidence has accumulated that implicates the N-terminus of Aβ as a region that may initiate the formation of damaging oligomeric species. Our laboratory has previously studied macrocyclic β-hairpin peptides derived from Aβ(16–22) and Aβ(30–36,) capable of forming hexamers that can be observed by X-ray crystallography and SDS-PAGE. To better mimic oligomers of full length Aβ, we use an orthogonal protecting group strategy during the synthesis to append residues from Aβ(1–14) to the parent macrocyclic β-hairpin peptide 1, which comprises Aβ(16–22) and Aβ(30–36). The N-terminally extended peptides N+1, N+2, N+4, N+6, N+8, N+10, N+12, and N+14 assemble to form dimers, trimers, and hexamers in solution-phase studies. X-ray crystallography reveals that peptide N+1 assembles to form a hexamer that is composed of dimers and trimers. These observations are consistent with a model in which the assembly of Aβ oligomers is driven by hydrogen bonding and hydrophobic packing of the residues from the central and C-terminal regions, with the N-terminus of Aβ accommodated by the oligomers as an unstructured tail.

Introduction: Endovenous stenting is being increasingly used for the management of iliofemoral venous outflow obstruction due to thrombotic or non-thrombotic iliac vein lesions (NIVL). Dedicated ve...

In chronic venous ulcers (CVUs), which account for up to 75% of leg ulcers, the inflammatory stage of wound healing fails to down-regulate, preventing progression to proliferation, remodeling and eventual epithelialisation. The roles of reactive oxygen species (ROS) in the oxidative burst and pathogen killing are well known, but ROS also have important functions in extra-cellular and intra-cellular signalling. Iron deposition, resulting from venous reflux, primes macrophages towards a persistent inflammatory response, with ongoing stimulation by bacteria potentially playing a role. Generation of excessive ROS by activated inflammatory cells causes tissue destruction and disintegration of the dermis, and then at later stages, a failure to heal. Here, we review the evidence for ROS in CVU formation and in normal and delayed healing. We also discuss how ROS modulation might be used to influence the healing of these complex wounds, which cause long-term morbidity and are associated with a significant financial burden to healthcare systems.

Murine models are widely used valuable tools to study deep vein thrombosis. Leading experts in venous thrombosis research came together through the American Venous Forum to develop a consensus on maximizing the utility and application of available mouse models of venous thrombosis. In this work, we provide an algorithm for model selection, with discussion of the advantages, disadvantages, and applications of the main mouse models of venous thrombosis. Additionally, we provide a detailed surgical description of the models with guidelines to validate surgical technique.

Vascular smooth muscle cells (VSMCs) contribute to the deposition of extracellular matrix proteins (ECMs), including Type IV collagen, in the vessel wall. ECMs coordinate communication among different cell types, but mechanisms underlying this communication remain unclear. Our previous studies have demonstrated that X-box binding protein 1 (XBP1) is activated and contributes to VSMC phenotypic transition in response to vascular injury. In this study, we investigated the participation of XBP1 in the communication between VSMCs and vascular progenitor cells (VPCs). Immunofluorescence and immunohistology staining revealed that Xbp1 gene was essential for type IV collagen alpha 1 (COL4A1) expression during mouse embryonic development and vessel wall ECM deposition and stem cell antigen 1-positive (Sca1+)-VPC recruitment in response to vascular injury. The Western blot analysis elucidated an Xbp1 gene dose-dependent effect on COL4A1 expression and that the spliced XBP1 protein (XBP1s) increased protease-mediated COL4A1 degradation as revealed by Zymography. RT-PCR analysis revealed that XBP1s in VSMCs not only upregulated COL4A1/2 transcription but also induced the occurrence of a novel transcript variant, soluble type IV collagen alpha 1 (COL4A1s), in which the front part of exon 4 is joined with the rear part of exon 42. Chromatin-immunoprecipitation, DNA/protein pulldown and in vitro transcription demonstrated that XBP1s binds to exon 4 and exon 42, directing the transcription from exon 4 to exon 42. This leads to transcription complex bypassing the internal sequences, producing a shortened COL4A1s protein that increased Sca1+-VPC migration. Taken together, these results suggest that activated VSMCs may recruit Sca1+-VPCs via XBP1s-mediated COL4A1s secretion, leading to vascular injury repair or neointima formation.

Introduction Paraplegia post-thoracoabdominal aortic aneurysm (TAAA) repair remains both a devastating and poorly understood complication. We related temporal changes in cellular and protein composition of cerebrospinal fluid (CSF) to neurological outcomes after TAAA repair to gain mechanistic insights driving paraplegia. Method Patients undergoing TAAA repair (open or endovascular) with a CSF drain were prospectively recruited between 2016-2018. CSF was collected pre-operatively and 24-hourly until removal. Daily neurological examinations were performed by blinded neurologists to the study. CSF cell content was characterised by flow cytometry and proteome analysed by tandem-mass-tag proteomics. An in-vivo rat model was modified using 15 minutes of aortic occlusion to produce consistent paraplegia. Rats were analysed neuro-behaviourally and histologically. Result CSF was analysed from 52 patients (age: 70.27+/-11.4; 66% male; open (n=9), endovascular (n=43)). 12 developed paraplegia of whom 5 remained permanently-paraplegic. Demographics were comparable between paraplegics, those who recovered and without post-op neurology. Permanent paraplegia was associated with a significant infiltration of CSF CD45+ leucocytes (P3-fold higher in permanent-paraplegics CSF versus those who recovered (P=0.0008). ADVS-1 >15ng/ml predicted permanent paraplegia with 100% specificity. Pre-treatment with ADVS-1 inhibition significantly improved walking ( Conclusion Permanent paraplegia is associated with shedding of ADVS-1 from parenchymal cord into CSF and blood/spinal-cord barrier disruption leading to cord oedema/leucocyte infiltration. Pre-treatment with ADVS-1 inhibition led to neurobehavioural and histological improvements offering translational hope for this devastating complication. Take-home message ADVS-1 is a novel biomarker of paraplegia where accurate biomarkers have proven challenging but more importantly it has proven a therapeutic target with genuine translational potential.

A number of dedicated self expanding nitinol stents have been developed for use in the venous system, with both open cell (OC) and closed cell (CC) designs available. Data comparing these different designs are lacking. The objective of this study was to evaluate outcomes in patients treated with open and closed cells for unilateral chronic iliac vein obstruction.A single centre retrospective cohort study was conducted, including all patients treated with a dedicated nitinol venous stent between 2014 and 2019. Stent patency and details of re-interventions (including lysis, venoplasty, reinforcement, extension, arteriovenous fistula formation) were examined in the first post-operative year. Subgroup analysis described outcomes for patients treated with OC and CC stents ending above the inguinal ligament and those who required extension into the common femoral vein. Cox regression analysis was used to identify factors associated with loss of primary patency.A total of 207 patients were included (OC 100 patients, CC 107 patients). There was no significant difference between the groups for age (OC 42 years, CC 44 years); gender (OC and CC 67% female); presence of post-thrombotic lesions (OC 71%, CC 73%); stenting across the inguinal ligament (OC 58%, CC 56%), or presence of inflow disease (OC 49%, CC 47%). Primary and cumulative patency at 12 months were similar between groups (primary: OC 63%, CC 65%; cumulative: OC 93%, CC 90%). Patients with a CC stent across the inguinal ligament had a greater risk of needing multiple re-interventions at one year compared with those with an OC stent (odds ratio 2.84, 95% confidence interval [CI] 1.16 - 6.9) but overall, the only factor significantly associated with loss of primary patency was inflow vessel disease (hazard ratio 3.39, 95% CI 1.73 - 6.62, p.001).OC and CC dedicated nitinol venous stents were observed to perform similarly in terms of patency and symptom improvement at one year. Disease of the inflow vessels was the most important factor associated with a loss of stent patency irrespective of stent design.

Venous valve (VV) failure causes chronic venous insufficiency, but the molecular regulation of valve development is poorly understood. A primary lymphatic anomaly, caused by mutations in the receptor tyrosine kinase EPHB4, was recently described, with these patients also presenting with venous insufficiency. Whether the venous anomalies are the result of an effect on VVs is not known. VV formation requires complex 'organization' of valve-forming endothelial cells, including their reorientation perpendicular to the direction of blood flow. Using quantitative ultrasound we identified substantial VV aplasia and deep venous reflux in patients with mutations in EPHB4. We used a GFP reporter, in mice, to study expression of its ligand, ephrinB2, and analysed developmental phenotypes following conditional deletion of floxed Ephb4 and Efnb2 alleles. EphB4 and ephrinB2 expression patterns were dynamically regulated around organizing valve-forming cells. Efnb2 deletion disrupted the normal endothelial expression patterns of the gap junction proteins connexin37 and connexin43 (both required for normal valve development) around reorientating valve-forming cells, and produced deficient valve-forming cell elongation, reorientation, polarity, and proliferation. Ephb4 was also required for valve-forming cell organization, and subsequent growth of the valve leaflets. These results uncover a potentially novel cause of primary human VV aplasia.

Objective Thrombophilia is a prothrombotic condition that increases the risk of venous thromboembolism. It is unclear whether the presence of thrombophilia alters the clinical outcomes after deep venous stenting. The aim of the present study was to examine the relationship between thrombophilia and outcomes after stenting for post-thrombotic syndrome. Methods Consecutive patients (2012-2017) receiving a nitinol venous stent for chronic post-thrombotic venous occlusive disease with a minimum of 18 months of follow-up in one center using the same anticoagulation protocol were included. The clinical history and thrombophilia testing results were reviewed. The outcomes were stent patency, which was assessed using duplex ultrasonography at 24 hours, 2 and 6 weeks, 3 months, 6 months, and annually thereafter; and reinterventions, which were performed when the stent diameter was Results Of the 136 patients who had undergone intervention, 55 (40%) had had a provoked deep vein thrombosis (DVT) and 81 (60%) had had an unprovoked DVT and had therefore undergone thrombophilia testing. Of the 81 patients, 38 (47%) had had either inherited (n = 19; 50%) or acquired (n = 19; 50%) thrombophilia. Of the 136 patients who had undergone stenting, 68 had required reintervention (50%) during follow-up to maintain stent patency. Of the 55 patients with a provoked DVT, 29 (53%) had required reintervention. Of the 81 patients with an unprovoked DVT, 39 (48%) had required reintervention (P = .420). Of the 38 patients with unprovoked DVT and thrombophilia, 17 (45%) had required reintervention. Of the 43 patients with unprovoked DVT and no thrombophilia, 22 (51%) had required reintervention (P = .766). The cumulative patency rate was 80% for patients with provoked DVT and 88% for those with unprovoked DVT (P = .193). The presence of thrombophilia was not associated with patency loss (92% cumulative patency for patients with thrombophilia and 84% for patients without thrombophilia; P = .307). Conclusions Using our anticoagulation protocol, patients with and without thrombophilia had similar clinical outcomes after deep venous stenting and should not be excluded from iliofemoral venous stenting. We found no significant differences in outcomes in conjunction with appropriate postoperative anticoagulation therapy.

Reactive oxygen species (ROS) have physiological roles as second messengers, but can also exert detrimental modifications on DNA, proteins and lipids if resulting from enhanced generation or reduced antioxidant defense (oxidative stress). Venous thrombus (DVT) formation and resolution are influenced by ROS through modulation of the coagulation, fibrinolysis, proteolysis and the complement system, as well as the regulation of effector cells such as platelets, endothelial cells, erythrocytes, neutrophils, mast cells, monocytes and fibroblasts. Many conditions that carry an elevated risk of venous thrombosis, such as the Antiphospholipid Syndrome, have alterations in their redox homeostasis. Dietary and pharmacological antioxidants can modulate several important processes involved in DVT formation, but their overall effect is unknown and there are no recommendations regarding their use. The development of novel antioxidant treatments that aim to abrogate the formation of DVT or promote its resolution will depend on the identification of targets that enable ROS modulation confined to their site of interest in order to prevent off-target effects on physiological redox mechanisms. Subgroups of patients with increased systemic oxidative stress might benefit from unspecific antioxidant treatment, but more clinical studies are needed to bring clarity to this issue.

OBJECTIVE/BACKGROUND The aim was to assess two year outcomes with placement of the Vici Venous Stent® in patients with chronic iliofemoral venous occlusions (complete blockage). METHODS This was a retrospective single centre study comprising patients treated with the Vici Venous Stent for venographically verified iliofemoral venous occlusion and post-thrombotic syndrome (Villalta score ≥ 5 points) at least 12 months after acute deep vein thrombosis. Venography and intravascular ultrasound were used peri-operatively; duplex ultrasound was used to assess stent patency during follow up. RESULTS Eighty-eight patients (101 limbs) had stent placement between March 2014 and October 2016. Median pre-treatment Villalta score was 14 (range 5-33). Stenting extended across the inguinal ligament in 63 limbs (62%) in order to land in a healthy venous segment. Six patients (7%) required endophlebectomy and fistula creation. Median imaging follow up was 21 months (range 0-41 months). Primary, assisted primary and secondary patency rates at one year were 59%, 78%, and 87%, respectively, and two years 51%, 73%, and 82%, respectively. Forty-three limbs (43%) had re-intervention (lysis, venoplasty, and/or placement of stent) during follow up; median time to re-intervention was 32 days (range 0-520 days). At 24 months, 37 of 53 limbs (70%) with available Villalta assessment showed clinically significant improvement (>30% reduction of baseline score). Villalta scores at the 6, 12, and 24 month clinical follow up were significantly lower than before stenting (p

Supplemental Digital Content is available in the text., Background: Radiation exposure during fluoroscopically guided interventions such as endovascular aortic repair (EVAR) is a growing concern for operators. This study aimed to measure DNA damage/repair markers in operators perfoming EVAR. Methods: Expression of the DNA damage/repair marker, γ-H2AX and DNA damage response marker, phosphorylated ataxia telangiectasia mutated (pATM), were quantified in circulating lymphocytes in operators during the peri-operative period of endovascular (infrarenal, branched, and fenestrated) and open aortic repair using flow cytometry. These markers were separately measured in the same operators but this time wearing leg lead shielding in addition to upper body protection and compared with those operating with unprotected legs. Susceptibility to radiation damage was determined by irradiating operators’ blood in vitro. Results: γ-H2AX and pATM levels increased significantly in operators immediately after branched endovascular aortic repair/fenestrated endovascular aortic repair (P

Aims Dysfunctional matrix turnover is present at sites of abdominal aortic aneurysm (AAA) and leads to the accumulation of monomeric tropoelastin rather than cross-linked elastin. We used a gadolinium-based tropoelastin-specific magnetic resonance contrast agent (Gd-TESMA) to test whether quantifying regional tropoelastin turnover correlates with aortic expansion in a murine model. The binding of Gd-TESMA to excised human AAA was also assessed. Methods and results We utilized the angiotensin II (Ang II)-infused apolipoprotein E gene knockout (ApoE-/-) murine model of aortic dilation and performed in vivo imaging of tropoelastin by administering Gd-TESMA followed by late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) and T1 mapping at 3 T, with subsequent ex vivo validation. In a cross-sectional study (n = 66; control = 11, infused = 55) we found that Gd-TESMA enhanced MRI was elevated and confined to dilated aortic segments (control: LGE=0.13 ± 0.04 mm2, control R1= 1.1 ± 0.05 s-1 vs. dilated LGE=1.0 ± 0.4 mm2, dilated R1 =2.4 ± 0.9 s-1) and was greater in segments with medium (8.0 ± 3.8 mm3) and large (10.4 ± 4.1 mm3) compared to small (3.6 ± 2.1 mm3) vessel volume. Furthermore, a proof-of-principle longitudinal study (n = 19) using Gd-TESMA enhanced MRI demonstrated a greater proportion of tropoelastin: elastin expression in dilating compared to non-dilating aortas, which correlated with the rate of aortic expansion. Treatment with pravastatin and aspirin (n = 10) did not reduce tropoelastin turnover (0.87 ± 0.3 mm2 vs. 1.0 ± 0.44 mm2) or aortic dilation (4.86 ± 2.44 mm3 vs. 4.0 ± 3.6 mm3). Importantly, Gd-TESMA-enhanced MRI identified accumulation of tropoelastin in excised human aneurysmal tissue (n = 4), which was confirmed histologically. Conclusion Tropoelastin MRI identifies dysfunctional matrix remodelling that is specifically expressed in regions of aortic aneurysm or dissection and correlates with the development and rate of aortic expansion. Thus, it may provide an additive imaging marker to the serial assessment of luminal diameter for surveillance of patients at risk of or with established aortopathy.

Murine models are widely used valuable tools to study deep vein thrombosis. Leading experts in venous thrombosis research came together through the American Venous Forum to develop a consensus on maximizing the utility and application of available mouse models of venous thrombosis. In this work, we provide an algorithm for model selection, with discussion of the advantages, disadvantages, and applications of the main mouse models of venous thrombosis. Additionally, we provide a detailed surgical description of the models with guidelines to validate surgical technique.

Introduction This review aims to provide an update on the management of deep vein thrombosis (DVT). Sources of data A systematic search of PubMed, Google Scholar and Cochrane databases was carried out. Areas of agreement Direct oral anticoagulants (DOACs) are as effective and easier to use than vitamin K antagonists for the treatment of DVT. Catheter-directed thrombolysis can reduce post thrombotic syndrome in patients with iliofemoral DVT. Compression bandaging can help heal a venous ulcer. Areas of controversy Compression hosiery to prevent post thrombotic syndrome. Long-term evidence to show clinical benefit of using endovenous therapies to restore deep vein patency. Growing points Developing imaging methods to identify patients who would benefit from venous thrombolysis. The evolution of dedicated venous stents. Areas timely for developing research Understanding the mechanisms that lead to stent occlusion and investigation into the appropriate treatments that could prevent in-stent thrombosis is required.

Deep vein thrombosis and common complications, including pulmonary embolism and post-thrombotic syndrome, represent a major source of morbidity and mortality worldwide. Experimental models of venous thrombosis have provided considerable insight into the cellular and molecular mechanisms that regulate thrombus formation and subsequent resolution. Here, we critically appraise the ex vivo and in vivo techniques used to assess venous thrombosis in these models. Particular attention is paid to imaging modalities, including magnetic resonance imaging, micro–computed tomography, and high-frequency ultrasound that facilitate longitudinal assessment of thrombus size and composition.

Successful management of acute deep vein thrombosis and post-thrombotic syndrome depends on careful patient selection and detailed investigation of thrombus extent, composition, and anatomy. This article reviews the use of computerized tomography and magnetic resonance imaging in the assessment of central deep veins of the pelvis and addresses new developments within the field. Despite drawbacks of each imaging modality, when contemplating deep venous reconstruction, cross-sectional imaging should be considered for preoperative planning and to compliment intraoperative imaging tools, including intravascular ultrasound and contrast venography.

Background: Elastolysis and ineffective elastogenesis favor the accumulation of tropoelastin, rather than cross-linked elastin, in atherosclerotic plaques. We developed gadolinium-labeled tropoelastin-specific magnetic resonance contrast agents for tropoelastin imaging in animal models. Methods and Results: Two peptides, VVGSPSAQDEASPLS and YPDHVQYTHY, were selected to target tropoelastin. In vitro binding, relaxivity, and biodistribution experiments enabled characterization of the probes and selecting the best candidate for in vivo magnetic resonance imaging. Magnetic resonance imaging was performed in atherosclerotic apolipoprotein E–deficient mice and New Zealand white rabbits with stable and rupture-prone plaques using a gadolinium-labeled tropoelastin-specific magnetic resonance contrast agent. In addition, human carotid endarterectomy specimens were imaged ex vivo. The VVGSPSAQDEASPLS-based probe discriminated between tropoelastin and cross-linked elastin (64%±7% versus 1%±2%; P =0.001), had high in vitro relaxivity in solution (r 1-free =11.7±0.6 [mmol/L] −1 s −1 , r 1-bound to tropoelastin =44±1 [mmol/L] − 1 s − 1 ), and favorable pharmacokinetics. In vivo mice vascular enhancement (4 weeks=0.13±0.007 mm 2 , 8 weeks=0.22±0.01 mm 2 , 12 weeks=0.33±0.01 mm 2 ; P 1 relaxation rate (4 weeks=[0.90±0.01]/s, 8 weeks=[1.40±0.03]/s, 12 weeks=[1.87±0.04]/s; P 2 ; R 1 =[1.37±0.03]/s) and control (0.10±0.005 mm 2 ; R 1 =[0.87±0.05]/s) mice showed less enhancement. Rupture-prone rabbit plaques had higher R 1 relaxation rate compared with stale plaques (R 1 =[2.26±0.1]/s versus R 1 =[1.43±0.02]/s; P =0.001) after administration of the gadolinium-labeled tropoelastin-specific magnetic resonance contrast agent that allowed detection of rupture-prone plaques with high sensitivity (84.4%) and specificity (92.3%). Increased vascular R 1 relaxation rate was observed in carotid endarterectomy plaques after soaking (R 1pre =[1.1±0.26]/s versus R 1post =[3.0±0.1]/s; P =0.01). Ex vivo analyses confirmed the magnetic resonance imaging findings and showed uptake of the contrast agent to be specific for tropoelastin. Conclusions: Magnetic resonance imaging of tropoelastin provides a novel biomarker for atherosclerotic plaque progression and instability.

We note with disappointment Doss’s suggestion that occupational radiation exposure should be considered as potentially beneficial. This comes at a time when the entire interventionist community is trying to impress on their young trainees, many of whom will be exposed to radiation several times a week, performing in some cases lengthy fluoroscopically guided procedures over a 40-year career, the importance of protecting against this exposure. We are aware that Doss and his group extol the virtues of not sparing irradiation to ensure proper screening, diagnosis, and treatment of patients. Although we would not advocate avoiding the use of radiation …

Leukocyte-released antimicrobial peptides contribute to pathogen elimination and activation of the immune system. Their role in thrombosis is incompletely understood. Here we show that the cathelicidin LL-37 is abundant in thrombi from patients with acute myocardial infarction. Its mouse homologue, CRAMP, is present in mouse arterial thrombi following vascular injury, and derives mainly from circulating neutrophils. Absence of hematopoietic CRAMP in bone marrow chimeric mice reduces platelet recruitment and thrombus formation. Both LL-37 and CRAMP induce platelet activation in vitro by involving glycoprotein VI receptor with downstream signaling through protein tyrosine kinases Src/Syk and phospholipase C. In addition to acute thrombosis, LL-37/CRAMP-dependent platelet activation fosters platelet–neutrophil interactions in other inflammatory conditions by modulating the recruitment and extravasation of neutrophils into tissues. Absence of CRAMP abrogates acid-induced lung injury, a mouse pneumonia model that is dependent on platelet–neutrophil interactions. We suggest that LL-37/CRAMP represents an important mediator of platelet activation and thrombo-inflammation., Cathelicidins are antimicrobial peptides that eliminate pathogens and contribute to the innate immune response. Here the authors show that neutrophil-derived LL-37/CRAMP induces platelet activation and promotes arterial thrombosis and thrombo-inflammation.

BACKGROUND: Hypoxia within acute venous thrombi is thought to drive resolution through stabilisation of hypoxia inducible factor 1 alpha (HIF1α). Prolyl hydroxylase domain (PHD) isoforms are critical regulators of HIF1α stability. Non-selective inhibition of PHD isoforms with l-mimosine has been shown to increase HIF1α stabilisation and promote thrombus resolution. OBJECTIVE: The aim of this study was to investigate the therapeutic potential of PHD inhibition in venous thrombus resolution. METHODS: Thrombosis was induced in the inferior vena cava of mice using a combination of flow restriction and endothelial activation. Gene and protein expression of PHD isoforms in the resolving thrombus was measured by RT-PCR and immunohistochemistry. Thrombus resolution was quantified in mice treated with pan PHD inhibitors AKB-4924 and JNJ-42041935 or inducible all-cell Phd2 knockouts by micro-computed tomography, 3D high frequency ultrasound or endpoint histology. RESULTS: Resolving venous thrombi demonstrated significant temporal gene expression profiles for PHD2 and PHD3 (P 0.05). CONCLUSIONS: This data suggests that PHD-mediated thrombus neovascularisation has a limited role in the resolution of venous thrombi. Directly targeting angiogenesis alone may not be a viable therapeutic strategy to enhance venous thrombus resolution. ispartof: THROMBOSIS RESEARCH vol:169 pages:105-112 ispartof: location:United States status: published

Surgery is associated with an increased risk of venous thromboembolic events (VTE) including deep vein thrombosis and pulmonary embolism. Although the current treatment regiments such as mechanical manipulation and administration of pharmacological prophylaxis significantly reduced the incidence of postsurgical VTE, they remain a major cause of postoperative morbidity and mortality worldwide. The pathophysiology of venous thrombosis traditionally emphasizes the series of factors that constitute Virchow triad of factors. However, inflammation can also be a part of this by giving rise to a hypercoagulable state and endothelial damage. The inflammatory response after surgery, which is initiated by a cytokine "storm" and occurs within hours of surgery, creates a prothrombotic environment that is further accentuated by several cellular processes including neutrophil extracellular traps formation, platelet activation, and the generation of tissue factor-bearing microparticles. Although such inflammatory markers are elevated in undergoing surgery, the precise mechanism by which they give rise to venous thrombosis is poorly understood. Here, we discuss the potential mechanisms linking inflammation to thrombosis, and highlight strategies that may minimize surgical inflammation and reduce the incidence of postoperative VTE.

Activation of proteolytic mechanisms at the cell surface through the activity of urokinase-type plasminogen activator (uPA) bound to its receptor, uPAR, is an important process in wound healing. The soluble forms of uPAR (suPAR and its fragments I, II, and III) have nonproteolytic functions that include chemotaxis, adhesion, and proliferation, which also have a role in wound healing. The aim of this study was to determine whether suPAR and its cleaved fragments are present in venous ulcers and whether their levels are associated with healing.Ulcer exudates were collected from patients with venous leg ulcers (n = 30). Healing was defined as complete re-epithelialization within 6 months of compression therapy. Time-resolved fluorescence immunoassays were validated for quantification of suPAR and its fragments in ulcer exudates. The effect of exudates on keratinocyte migration was analyzed by an in vitro scratch assay.Ulcer exudates from patients who healed (n = 9) had approximately threefold higher levels of intact suPAR (P = .005), twofold higher levels of suPARI (P = .03), and approximately threefold higher levels suPARII-III (P.0001) compared with nonhealers (n = 21). Exudate from healing ulcers stimulated keratinocyte migration (P = .02), whereas depletion of suPAR from exudates resulted in cell apoptosis.We conclude that suPAR and its fragments are present in the environs of venous ulcers and may act as indicators of the propensity of venous ulcers to heal, with suPARII-III being the best discriminator. We speculate that suPAR and its fragments may have a role in the maintenance of an optimal ulcer-healing environment.

Recent technological advances have allowed researchers to interrogate the genetic basis of abdominal aortic aneurysms in great detail. The results from these studies are expected to transform our understanding of this complex disease with both multiple genetic and environmental risk factors. Clinicians need to keep abreast of these genetic findings and understand the implications for their practice. Patients will become increasingly informed on genetic risk, and a new era of individualized risk assessment for AAA is just beginning. This brief update aims to provide the clinician with a succinct précis of the recent progress in this area.

Introduction: The poor retention of cells delivered into ischemic tissue is a hurdle that needs to be addressed for cell therapy to be effective. We have previously shown that CD16+ monocytes expressing upregulated cell adhesion markers are mobilized in critical limb ischemia (CLI) and salvage limbs in pre-clinical studies of hindlimb ischemia (HLI). We hypothesized that these cells are well retained following delivery into ischemic muscle. Methods and Results: CD16+ and CD16- monocytes were isolated from CLI patients, fluorescently labeled with QuantumDots and injected into the adductor muscle of nude athymic mice following HLI (n=15/group). Flow cytometric analysis of cell suspensions from injected muscle showed higher 3 and 7 day retention of CD16+ compared with CD16- monocytes (P7 ) were radiolabeled with Indium 111 and injected into ischemic legs. Cells were tracked at 30mins, 2, 24 and 72 hours using whole-body γ-camera imaging: radiodecay-corrected retention percentages were 60.0, 37.4, 29.9 and 22.0% respectively with evidence of “washout” into the liver. Analysis of muscle biopsies showed >85% viability of the cells at 10 days and areas of increased arteriogenesis compared with remote, non-injected muscle. Conclusion: CD16+ Mo are preferentially retained within ischemic muscle in experimental HLI. This first in man study shows these cells remain viable in ischemic tissue. Isolation of sufficient numbers of these cells for delivery directly into poorly perfused muscle may provide a more effective cell therapy for CLI patients.

Introduction: Cell therapy using unselected mononuclear cell populations has had modest benefits in patients with critical limb ischemia (CLI). We hypothesized that tissue-remodeling monocytes, identified by their expression of CD16 (CD16+ Mo), may be a novel cellular therapy for CLI. Methods and Results: Flow cytometry showed that the proportion of circulating CD16+ Mo was greater in CLI patients (n=25) compared with matched controls (n=15, P6 cells injected into the adductor muscles of nude athymic mice following femoral artery excision. More ischemic hindlimbs were salvaged when treated with CD16+ compared with CD16- Mo (83% [10/12] vs 17% [2/12] limbs, P Conclusion: Circulating CD16+ Mo from CLI patients have increased expression of adhesion markers, are preferentially retained within ischemic muscle and promote robust arteriogenesis and limb salvage in experimental HLI. This monocyte subset may be an effective cellular therapy for CLI.

We describe a mutation inLMOD1, which predisposes individuals to thoracic aortic aneurysms and dissections in a large multi-generation British family. Exome variant profiles for the proband and two distantly related affected relatives were generated and a rare protein-altering, heterozygous variant was identified, present in all the exome-sequenced affected individuals. The allele c.1784T>C, p.(V595A) inLMOD1is located in a known actin-binding WH2 domain and is carried by all living affected individuals in the family.LMOD1was further assessed in a consecutive series of 98 UK TAAD patients and one further mutation was found, yielding an incidence of ∼2% in our study group. Assessment ofLMOD1in international TAAD cohorts discovered nine other missense variants of which three were classed as likely pathogenic.Validation ofLMOD1was undertaken using a zebrafish animal model. Knock-down of bothlmod1aandlmod1bparalogs using morpholino oligonucleotides showed a reproducible abnormal phenotype involving the aortic arches under off-target controls. Injection of the humanLMOD1c.1784T>C, p.(V595A) mutation demonstrated a likely dominant negative effect and illustrated a loss of function cause.Mutations found in the WH2 actin-binding domain ofLMOD1may delay actin polymerization and therefore compromise actin length, dynamics and interaction with myosin in the smooth muscle contraction pathway.

Mutations in the gap junction protein connexin47 (Cx47) are associated with lymphedema. However, the role of Cx47 in lymphatic pathophysiology is unknown. We demonstrate that Cx47 is expressed in lymphatic endothelial cells by whole-mount immunostaining and qPCR. To determine if Cx47 plays a role in lymphatic vessel function we analysed Cx47-/- mice. Cx47-deficiency did not affect lymphatic contractility (contractile amplitude or frequency) or lymphatic morphology (vessel diameter or number of valves). Interstitial fluid drainage or dendritic cell migration through lymphatic vessels was also not affected by Cx47-deficiency. Cx47 is dispensable for long-chain fatty acid absorption from the gut but rather promotes serum lipid handling as prolonged elevated triglyceride levels were observed in Cx47-deficient mice after oral lipid tolerance tests. When crossed with Apolipoprotein E-deficient (Apoe-/-) mice, LDL-cholesterol was decreased in young Cx47-/-Apoe-/- adults as compared to Apoe-/- mice, which was inverted later in life. Finally, advanced atherosclerotic plaques in thoracic-abdominal aortas of 15 months-old mice tended to be larger in Cx47-/-Apoe-/- mice. These plaques contained fewer macrophages but similar amounts of T lymphocytes, collagen and lipids than plaques of Apoe-/- mice. In conclusion, Cx47 is expressed in lymphatic endothelium and seems modestly implicated in multiple aspects of lymphatic pathophysiology.

Rationale : Abdominal aortic aneurysms constitute a degenerative process in the aortic wall. Both the miR-29 and miR-15 families have been implicated in regulating the vascular extracellular matrix. Objective : Our aim was to assess the effect of the miR-15 family on aortic aneurysm development. Methods and Results : Among the miR-15 family members, miR-195 was differentially expressed in aortas of apolipoprotein E–deficient mice on angiotensin II infusion. Proteomics analysis of the secretome of murine aortic smooth muscle cells, after miR-195 manipulation, revealed that miR-195 targets a cadre of extracellular matrix proteins, including collagens, proteoglycans, elastin, and proteins associated with elastic microfibrils, albeit miR-29b showed a stronger effect, particularly in regulating collagens. Systemic and local administration of cholesterol-conjugated antagomiRs revealed better inhibition of miR-195 compared with miR-29b in the uninjured aorta. However, in apolipoprotein E–deficient mice receiving angiotensin II, silencing of miR-29b, but not miR-195, led to an attenuation of aortic dilation. Higher aortic elastin expression was accompanied by an increase of matrix metalloproteinases 2 and 9 in mice treated with antagomiR-195. In human plasma, an inverse correlation of miR-195 was observed with the presence of abdominal aortic aneurysms and aortic diameter. Conclusions : We provide the first evidence that miR-195 may contribute to the pathogenesis of aortic aneurysmal disease. Although inhibition of miR-29b proved more effective in preventing aneurysm formation in a preclinical model, miR-195 represents a potent regulator of the aortic extracellular matrix. Notably, plasma levels of miR-195 were reduced in patients with abdominal aortic aneurysms suggesting that microRNAs might serve as a noninvasive biomarker of abdominal aortic aneurysms.

Peripheral arterial disease (PAD) affects 27 million individuals in Europe and North America.1 This condition causes a severe restriction of blood flow that can lead to critical limb ischemia (CLI), a condition characterized by rest pain, ulceration, or gangrene, which is associated with limb loss in ≈25% of cases.2 The ischemic limb can be revascularized by endovascular techniques (angioplasty/stenting) or surgical bypass. Imaging modalities, including duplex ultrasound, MR angiography, computer tomographic angiography, or intra-arterial angiography, are used to assess the extent of disease, plan intervention, and confirm the patency of major blood vessels after intervention. These techniques do not provide information about perfusion at the tissue level. An early relatively crude method for assessing ischemic limbs, venous occlusion plethysmography3 relies on the principle that the volume of the limb is dependent on the arterial inflow when venous drainage is occluded. Under resting conditions, ≤70% of blood flow to the limb is directed to skeletal muscle, with the remainder to the skin circulation.4 Venous occlusion plethysmography provides a global indication of limb perfusion but gives no anatomic information and cannot delineate segmental perfusion deficits. It is influenced by numerous factors, such as ambient temperature and arteriovenous shunting that may lead to erroneous readings. Objective measurement of limb perfusion would particularly benefit patients with CLI but most attempts at addressing this have used patients with claudication. The latter can lead to CLI but is a less severe form of PAD that is often treated conservatively and is characterized by pain only when walking as opposed to pain at rest or gangrene. An accurate, noninvasive method of measuring limb perfusion would aid the diagnosis and treatment of PAD and could be combined with conventional angiography to provide both functional …

The formation of new vascular channels within and around venous thrombus contributes to its resolution. Neovascularisation arising from the surrounding vein may facilitate this process. Treatment of cancer patients with anti-angiogenic agents can lead to increased incidence of venous thromboembolic events, but the effect of these agents on the processes that govern thrombus resolution are unclear. The aim of this study was to determine the effect of anti-angiogenic treatment with 2-methoxyestradiol (2ME) on (i) angiogenic response in the thrombosed vein and (ii) venous thrombus resolution.Venous thrombus was induced in the inferior vena cava (IVC) of 36 adult male BALB/C mice. Thrombosed mice received either the anti-angiogenic agent, 2ME (150 mg/kg/day, i/p), or vehicle control (n=18/group). In the thrombosed IVC of both groups: hypoxia-inducible factor (HIF) 1α, and its angiogenic targets, vascular endothelial growth factor (VEGF) and placental growth factor (PLGF), were quantified using enzyme-linked immunosorbent assays at days 1 and 10 post-thrombus induction (n=6/group); and inflammatory cell content, cell proliferation, and vein recanalisation were quantified using immunostaining and image analysis at day 10 (n=6/group).In the IVC of mice treated with 2ME compared with control: HIF1α (P0.005 and P0.02), VEGF (P0.005 and P0.02), and PLGF levels (P0.01 and P0.001) were reduced at days 1 and 10 post-thrombus induction respectively, and macrophage content (P0.005), neutrophil content (P0.01), vein recanalistion (P0.05), and thrombus resolution (P0.001) were also reduced at day 10.Anti-angiogenic treatment with 2ME supressed the HIF1-mediated angiogenic drive in local vein wall and attenuated venous thrombus resolution. The potential pro-thrombotic effect of anti-angiogenic agents should be carefully considered when managing venous thromboembolic events in cancer patients.