Interindividual heterogeneity in the hypoxic regulation of VEGF: significance for the development of the coronary artery collateral circulation

Studies of the retinal microcirculation using human donor eyes and high-resolution clinical imaging: Insights gained to guide future research in diabetic retinopathy

The microcirculation plays a key role in delivering oxygen to and removing metabolic wastes from energy-intensive retinal neurons. Microvascular changes are a hallmark feature of diabetic retinopathy (DR), a major cause of irreversible vision loss globally. Early investigators have performed landmark studies characterising the pathologic manifestations of DR. Previous works have collectively informed us of the clinical stages of DR and the retinal manifestations associated with devastating vision loss. Since these reports, major advancements in histologic techniques coupled with three-dimensional image processing has facilitated a deeper understanding of the structural characteristics in the healthy and diseased retinal circulation. Furthermore, breakthroughs in high-resolution retinal imaging have facilitated clinical translation of histologic knowledge to detect and monitor progression of microcirculatory disturbances with greater precision. Isolated perfusion techniques have been applied to human donor eyes to further our understanding of the cytoarchitectural characteristics of the normal human retinal circulation as well as provide novel insights into the pathophysiology of DR. Histology has been used to validate emerging in vivo retinal imaging techniques such as optical coherence tomography angiography. This report provides an overview of our research on the human retinal microcirculation in the context of the current ophthalmic literature. We commence by proposing a standardised histologic lexicon for characterising the human retinal microcirculation and subsequently discuss the pathophysiologic mechanisms underlying key manifestations of DR, with a focus on microaneurysms and retinal ischaemia. The advantages and limitations of current retinal imaging modalities as determined using histologic validation are also presented. We conclude with an overview of the implications of our research and provide a perspective on future directions in DR research.

Pathway-Specific Polygenic Risk Scores Identify Obstructive Sleep Apnea-Related Pathways Differentially Moderating Genetic Susceptibility to Coronary Artery Disease

BACKGROUND

Obstructive sleep apnea (OSA) and its features, such as chronic intermittent hypoxia, may differentially affect specific molecular pathways and processes in the pathogenesis of coronary artery disease (CAD) and influence the subsequent risk and severity of CAD events. In particular, competing adverse (eg, inflammatory) and protective (eg, increased coronary collateral blood flow) mechanisms may operate, but remain poorly understood. We hypothesize that common genetic variation in selected molecular pathways influences the likelihood of CAD events differently in individuals with and without OSA, in a pathway-dependent manner.

METHODS

We selected a cross-sectional sample of 471 877 participants from the UK Biobank, with 4974 ascertained to have OSA, 25 988 to have CAD, and 711 to have both. We calculated pathway-specific polygenic risk scores for CAD, based on 6.6 million common variants evaluated in the CARDIoGRAMplusC4D genome-wide association study (Coronary ARtery DIsease Genome wide Replication and Meta-analysis [CARDIoGRAM] plus The Coronary Artery Disease [C4D] Genetics), annotated to specific genes and pathways using functional genomics databases. Based on prior evidence of involvement with intermittent hypoxia and CAD, we tested pathway-specific polygenic risk scores for the HIF1 (hypoxia-inducible factor 1), VEGF (vascular endothelial growth factor), NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) and TNF (tumor necrosis factor) signaling pathways.

RESULTS

In a multivariable-adjusted logistic generalized additive model, elevated pathway-specific polygenic risk scores for the Kyoto Encyclopedia of Genes and Genomes VEGF pathway (39 genes) associated with protection for CAD in OSA (interaction odds ratio 0.86, P=6×10-4). By contrast, the genome-wide CAD PRS did not show evidence of statistical interaction with OSA.

CONCLUSIONS

We find evidence that pathway-specific genetic risk of CAD differs between individuals with and without OSA in a qualitatively pathway-dependent manner. These results provide evidence that gene-by-environment interaction influences CAD risk in certain pathways among people with OSA, an effect that is not well-captured by the genome-wide PRS. This invites further study of how OSA interacts with genetic risk at the molecular level and suggests eventual personalization of OSA treatment to reduce CAD risk according to individual pathway-specific genetic risk profiles.

Differentiating Microaneurysm Pathophysiology in Diabetic Retinopathy Through Objective Analysis of Capillary Nonperfusion, Inflammation, and Pericytes

Microaneurysms are biomarkers of microvascular injury in diabetic retinopathy (DR). Impaired retinal capillary perfusion is a critical pathogenic mechanism in the development of microvascular abnormalities. Targeting fundamental molecular disturbances resulting from capillary nonperfusion, such as increased vascular endothelial growth factor expression, does not always reverse the anatomic complications of DR, suggesting that other pathogenic mechanisms independent of perfusion also play a role. We stratify the effects of capillary nonperfusion, inflammation, and pericyte loss on microaneurysm size and leakage in DR through three-dimensional analysis of 636 microaneurysms using high-resolution confocal scanning laser microscopy. Capillary nonperfusion, pericyte loss, and inflammatory cells were found to be independent predictors of microaneurysm size. Nonperfusion alone without pericyte loss or inflammation was not a significant predictor of microaneurysm leakage. Microaneurysms found in regions without nonperfusion were significantly smaller than those found in regions with nonperfusion, and their size was not associated with pericyte loss or inflammation. In addition, microaneurysm size was a significant predictor of leakage in regions with nonperfusion only. This report refines our understanding of the disparate pathophysiologic mechanisms in DR and provides a histologic rationale for understanding treatment failure for microvascular complications in DR.

Association of lower serum irisin levels with diabetes mellitus: Irrespective of coronary collateral circulation, and syntax score

Objective:

Irisin is a myokine thought to be involved in the pathophysiological process of atherosclerosis with its’ cardiovascular protective effects. Patients with diabetes mellitus (DM) have lower levels of irisin. Therefore, we investigated whether there is a connection between irisin, DM, coronary collateral circulation (CCC), and SYNTAX scores representing coronary artery disease (CAD) severity.

Methods:

This study evaluated 86 patients who have at least one epicardial coronary artery with chronic total occlusion. We included Rentrop 0–1 into the poor CCC group (n=45) and Rentrop 2–3 into the good CCC group (n=41) and measured serum irisin levels.

Results:

Irisin levels did not differ (17585 [882–37741] pg/ml and (17504 [813–47683] pg/ml, p=0.772) between the two groups. Irisin levels were lower in patients with diabetes (n=41; 14485 [813–29398] pg/ml) than those without diabetes (n=45; 19724 [865–47683] pg/ml (p=0.002). Irisin was not correlated with SYNTAX scores. In multivariate analysis, DM (OR=0.463; CI: 0.184–0.783; p=0.012) was a negative predictor of good CCC development

Conclusion:

Although its level is decreased in patients with diabetes, serum irisin levels have no role in the pathophysiology of collateral development and CAD severity.

Study of the effect of vascular endothelial growth factor (VEGF) C(+405)G (rs2010963) single nucleotide polymorphism on the development of esophageal and gastric varices and risk of variceal bleeding in cirrhotic hepatitis C virus (HCV) patients (VEGF) C(+405)G IN esophageal and gastric varices

Background

HCV infection is a major worldwide cause of chronic liver diseases. Esophageal and gastric varices are common in cirrhotic patients due to concomitant portal hypertension. Variceal hemorrhage is a major decompensating event with high morbidity and mortality. Endothelial dysfunction, occurring in cirrhosis, facilitates the development of liver cirrhosis, portal hypertension and contributes to increased intrahepatic vascular resistance..VEGF family members are major regulators of blood vessel development and function.

Results

The study was conducted on 90 subjects admitted to Tropical Medicine Department, Alexandria Main University Hospital: 30 cirrhotic patients with endoscopically proven varices (group A), 30 cirrhotic patients without varices (group B), and 30 healthy controls (group C). All patients was subjected to detailed history taking and thorough clinical examination, laboratory investigations, ultrasound abdomen, upper gastrointestinal endoscopy, and genotyping for VEGF C(+405)G (rs2010963) by 5′ nuclease assay. The VEGF C(+405)G (rs2010963) GG genotype was associated with higher prevalence of esophageal and gastric varices and higher bleeding risk.

Conclusion

VEGF C(+405)G (rs2010963) is an important genetic determinant of esophageal varices, gastric varices, and correlates with variceal bleeding risk. Genetic testing of this SNP would be useful in prediction of esophageal and gastric varices and bleeding risk.

An Investigation of the Association Between Vascular Endothelial Growth Factor +405 G/C Polymorphism and Acute Liver Transplant Rejection in Iranian Liver Transplant Recipients

OBJECTIVES

Vascular endothelial growth factor is an endothelial-specific growth factor that promotes endothelial cell proliferation, differentiation, and survival; mediates endothelium-dependent vasodilatation; induces microvascular hyperpermeability; and participates in interstitial matrix remodeling. The aim of the present study was to investigate the association between +405 G/C polymorphism of vascular endothelial growth factor and the risk of liver rejection in liver transplant recipients.

MATERIALS AND METHODS

The present study included 124 patients with liver disease that led to liver transplant. There were 22 patients who experienced histologically proven acute liver rejection, and the other 102 patients showed no rejection. Both groups were matched for sex and age. The VEGF+405 G/C polymorphism was evaluated by the polymerase chain reaction-restriction fragment-length polymorphism method.

RESULTS

Our analyses showed no significant relationships between genotypes and alleles of +405 G/C and risk of acute liver transplant rejection.

CONCLUSIONS

Our report indicated that there was no association between the carrier states of +405 G/C gene polymorphism of vascular endothelial growth factor and acute rejection or nonrejection of liver transplant.

Differences in Tolerance to Hypoxia: Physiological, Biochemical, and Molecular-Biological Characteristics

Hypoxia plays an important role in the development of many infectious, inflammatory, and tumor diseases. The predisposition to such disorders is mostly provided by differences in basic tolerance to oxygen deficiency, which we discuss in this review. Except the direct exposure of different-severity hypoxia in decompression chambers or in highland conditions, there are no alternative methods for determining organism tolerance. Due to the variability of the detection methods, differences in many parameters between tolerant and susceptible organisms are still not well-characterized, but some of them can serve as biomarkers of susceptibility to hypoxia. At the moment, several potential biomarkers in conditions after hypoxic exposure have been identified both in experimental animals and humans. The main potential biomarkers are Hypoxia-Inducible Factor (HIF)-1, Heat-Shock Protein 70 (HSP70), and NO. Due to the different mechanisms of various high-altitude diseases, biomarkers may not be highly specific and universal. Therefore, it is extremely important to conduct research on hypoxia susceptibility biomarkers. Moreover, it is important to develop a method for the evaluation of organisms' basic hypoxia tolerance without the necessity of any oxygen deficiency exposure. This can contribute to new personalized medicine approaches' development for diagnostics and the treatment of inflammatory and tumor diseases, taking into account hypoxia tolerance differences.

Long-term Effect of CPAP Treatment on Cardiovascular Events in Patients With Resistant Hypertension and Sleep Apnea. Data From the HIPARCO-2 Study

BACKGROUND

There is some controversy about the effect of continuous positive airway pressure (CPAP) on the incidence of cardiovascular events (CVE). However, the incidence of CVE among patients with both obstructive sleep apnea (OSA) ans resistant hypertension (HR) has not been evaluated. Our objective was to analyze the long-term effect of CPAP treatment in patients with RH and OSA on the incidence of CVE.

METHODS

Multi-center, observational and prospective study of patients with moderate-severe OSA and RH. All the patients were followed up every 3-6 months and the CVE incidence was measured. Patients adherent to CPAP (at least 4h/day) were compared with those with not adherent or those who had not been prescribed CPAP.

RESULTS

Valid data were obtained from 163 patients with 64 CVE incidents. Treatment with CPAP was offered to 82%. After 58 months of follow-up, 58.3% of patients were adherent to CPAP. Patients not adherent to CPAP presented a non-significant increase in the total CVE incidence (HR:1.6; 95%CI: 0.96-2.7; p=0.07). A sensitivity analysis showed that patients not adherent to CPAP had a significant increase in the incidence of cerebrovascular events (HR: 3.1; CI95%: 1.07-15.1; p=0.041) and hypertensive crises (HR: 5.1; CI95%: 2.2-11.6; p=0.006), but the trend went in the opposite direction with respect to coronary events (HR: 0.22; CI95%: 0.05-1.02; p=0.053).

CONCLUSIONS

In patients with RH and moderate-severe OSA, an uneffective treatment with CPAP showed a trend toward an increase in the incidence of CVE (particularly neurovascular events and hypertensive crises) without any changes with respect to coronary events.

Angiogenic growth factors in myocardial infarction: a critical appraisal

In the recent past, substantial advances have been made in the treatment of myocardial infarction (MI). Despite the impact of these positive developments, MI remains to be a leading cause of morbidity as well as mortality. An interesting hypothesis is that the development of new blood vessels (angiogenesis) or the remodeling of preexisting collaterals may form natural bypasses that could compensate for the occlusion of an epicardial coronary artery. A number of angiogenic factors are proven to be elicited during MI. Exogenous supplementation of these growth factors either in the form of recombinant protein or gene would enhance the collateral vessel formation and thereby improve the outcome after MI. The aim of this review is to describe the nature and potentials of different angiogenic factors, their expression, their efficacy in animal studies, and clinical trials pertaining to MI.

Intermittent Hypoxia Induced Formation of "Endothelial Cell-Colony Forming Units (EC-CFUs)" Is Affected by ROS and Oxidative Stress

Intermittent hypoxia (IH)—the hallmark of obstructive sleep apnea (OSA)—increases leukocyte activation, production of NADPH-oxidase dependent reactive oxygen species (ROS) and oxidative stress, affecting endothelial function. However, IH and oxidative stress can also stimulate adaptive-protective mechanisms by inducing the development of Endothelial Cell-Colony Forming Units (EC-CFUs), which are considered as a good surrogate marker for endothelial progenitor cells (EPCs), and likely reflect a reparatory response to vascular damage or tissue ischemia by leukocytes. Blood samples were obtained from 15 healthy consenting volunteers to evaluate the effects of IH and sustained hypoxia (SH) in vitro on EC-CFUs development and functions. The variables measured included: their numbers, the area, the proliferative capacity and ROS production. Additionally, NADPH-oxidase, VEGF and nuclear factor-erythroid 2 related factor 2 (Nrf2) expression, as well as their paracrine effects on endothelial tube formation were determined. The involvement of ROS was probed using the anti-oxidant N-acetylcysteine (NAC) and NADPH-oxidase inhibitors apocynin and diphenyl-iodide. Compared to normoxia, IH-dependent increases in EC-CFUs numbers were observed, showing an individual donor-dependent trait. Also, the expression of VEGF and gp91phox, a subunit of NADPH-oxidase, were significantly increased. ROS production and oxidative stress markers were also significantly increased, but Nrf2 expression and colony size were unaffected by IH. Additionally, conditioned media harvested from IH- and SH-treated mature EC-CFUs, significantly increased endothelial tube formation. These effects were markedly attenuated or diminished by the ROS and NADPH-oxidase inhibitors employed. In conclusion, we show here for the first time that IH-associated oxidative stress promotes EC-CFUs' vascular and paracrine capacities through ROS. However, the large inter-individual variability expressed in EC-CFUs numbers and functions to a given IH stimulus, may represent an individual trait with a potential clinical significance.

Cardiotoxicity with vascular endothelial growth factor inhibitor therapy

Angiogenesis inhibitors targeting the vascular endothelial growth factor (VEGF) signaling pathway (VSP) have been important additions in the therapy of various cancers, especially renal cell carcinoma and colorectal cancer. Bevazicumab, the first VSP to receive FDA approval in 2004 targeting all circulating isoforms of VEGF-A, has become one of the best-selling drugs of all times. The second wave of tyrosine kinase inhibitors (TKIs), which target the intracellular site of VEGF receptor kinases, began with the approval of sorafenib in 2005 and sunitinib in 2006. Heart failure was subsequently noted, in 2-4% of patients on bevacizumab and in 3-8% of patients on VSP-TKIs. The very fact that the single-targeted monoclonal antibody bevacizumab can induce cardiotoxicity supports a pathomechanistic role for the VSP and the postulate of the "vascular" nature of VSP inhibitor cardiotoxicity. In this review we will outline this scenario in greater detail, reflecting on hypertension and coronary artery disease as risk factors for VSP inhibitor cardiotoxicity, but also similarities with peripartum and diabetic cardiomyopathy. This leads to the concept that any preexisting or coexisting condition that reduces the vascular reserve or utilizes the vascular reserve for compensatory purposes may pose a risk factor for cardiotoxicity with VSP inhibitors. These conditions need to be carefully considered in cancer patients who are to undergo VSP inhibitor therapy. Such vigilance is not to exclude patients from such prognostically extremely important therapy but to understand the continuum and to recognize and react to any cardiotoxicity dynamics early on for superior overall outcomes.

Prognostic evaluation of VEGFA genotypes and haplotypes in a cohort of Brazilian women with non metastatic breast cancer

Vascular Endothelial Growth Factor (VEGF) mediates angiogenesis, which is crucial for tumor development and progression. The present study aimed to evaluate the impact of VEGFA gene polymorphisms rs699947, rs833061, rs1570360, rs2010963 and rs3025039 on breast cancer features and prognosis. A cohort of Brazilian women (N = 1038) with unilateral non-metastatic breast cancer was evaluated. The association between VEGFA polymorphisms and histopathological features or pathological complete response (pCR) to neoadjuvant chemotherapy was evaluated by the Chi-square test, with calculation of the respective odds ratio (OR) and 95% confidence intervals (95% CI). The impact of individual categories on disease-free survival was evaluated using Kaplan-Meier curves and multivariate Cox proportional hazards regression models for calculation of adjusted hazard ratios (HRadjusted). Variant genotypes of rs699947 (CA + AA) were significantly associated with high-grade (G2 + G3) tumors (OR = 1.82; 95% CI = 1.15 - 2.89), and with shorter disease-free survival among patients treated with neoadjuvant chemotherapy followed by mastectomy (HRadjusted = 1.82; 95% CI = 1.16 - 2.86). Variant genotypes of rs833061 (TC + CC) were significantly associated with high-grade (G2 + G3) tumors (OR = 1.79; 95% CI = 1.12 - 2.84) and with positive lymph node status (OR = 1.34; 95% CI = 1.01 - 1.77), but showed no independent effect on disease-free survival. Variant haplotypes (*2 to *5) appear to favor pCR (OR = 7.1; 95% CI = 1.7 - 30.1). VEGFA genotyping may add to prognostic evaluation of breast cancer, with rs699947 being the most likely to contribute.

SNP and Haplotype Analysis of Vascular Endothelial Growth Factor (VEGF) Gene in Lung Cancer Patients of Kashmir

Vascular endothelial growth factor (VEGF) is a major mediator of angiogenesis involving tumor growth and metastasis. In this large case-control study, we investigated whether functional polymorphisms (+405C>G, +936C>T) in the VEGF gene are associated with the risk of lung cancer. The study investigates the association between variants of VEGF gene and lung cancer. We performed single nucleotide polymorphism (SNP), haplotype and linkage disequilibrium studies on 100 patients and 128 healthy controls with 2 SNPs in the VEGF gene. The results were analyzed using logistic regression models, adjusted for age and sex. No Significant association was detected between individual SNPs and lung cancer using all the models of inheritance (codominant, dominant, recessive, over dominant and additive) for finding an association between genotypes and the cancer risk. The P values obtained for two markers were non-significant (P>0.05). Haplotype analysis produced additional support for the non-association of individual haplotypes/all haplotypes with the cancer risk (Global association P=0.56). Our findings suggest the non-involvement of genetic variants (+405C>G, +936C>T) of the VEGF gene in the etiology of lung cancer.

Physicians Report Sleep Apnea Infrequently in Older and Older Vulnerable Adults

OBJECTIVES

To determine how often outpatient physician visits detect sleep apnea (SA) in older persons in the United States.

DESIGN

Retrospective Analysis.

SETTING

US non hospital and hospital based clinics.

PARTICIPANTS

US physicians.

MEASUREMENTS

National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey data from 1993 to 2011 were used to assess the frequency of physicians' coding diagnoses of SA in persons aged 65 and older. Which specialties are most likely to report SA, the most-common comorbid conditions reported with SA, and the likelihood of reporting SA in patient visits for dementia and preoperative care were assessed.

RESULTS

From 1993 to 2011, physicians reported SA in 0.3% of all office visits in persons aged 65 and older. SA reported in visits increased from 130,000 in 1993 to 2,070,000 in 2011, with an annual per capita visit reporting rate of 0.07% to 0.74%. In older populations, the proportion of documented SA visits by specialists rose, and that of primary care providers decreased. Older adults with a diagnosis of SA had higher average number of comorbidities than those without SA (1.8 vs 1.3). Reporting SA was low in visits with a diagnosis of dementia and classified as a preoperative visits.

CONCLUSION

In two nationwide surveys, SA reporting by physicians in elderly adults was 16 as greater in 2001 as in 1993, although reporting of SA remains infrequent (<1% of visits) even in vulnerable populations.

Endocan: a novel biomarker associated with well-developed coronary collateral circulation in patients with stable angina and chronic total occlusion

Angiogenesis and arteriogenesis have a crucial role in the formation of coronary collateral vessels. It has been shown that endocan and vascular cell adhesion molecule-1 (VCAM-1) are potential angiogenetic factors. We investigated the relationship between serum endocan levels and grade of coronary collaterals, and also the correlation of endocan levels with serum VCAM-1 levels. Patients with stable angina and at least one total coronary occlusion at invasive coronary angiography were included in our study. Collateral degree was graded according to Rentrop and Cohen's classification. Patients who had grade 0 or 1 collateral vessels were included in the poorly-developed collateral group, and those with grade 2 or 3 coronary collateral vessels were included in the well-developed collateral group. Serum endocan and VCAM-1 levels were significantly higher in the well-developed collateral group (436.6 ± 213.3 ng/mL vs. 216.1 ± 78.5 ng/mL, p < .001; 11.02 ± 6.58 ng/mL vs. 6.78 ± 1.14 ng/mL, p < .001, respectively). In a logistic regression analysis, only serum endocan level remained as an independent predictor for good collateral development. In the ROC curve analysis, 282 ng/mL endocan level had an a 82 % sensitivity and 86 % specificity for prediction of the well-developed collateral group. Higher endocan level was related to better coronary collateral development. In the event that these results are confirmed in further studies, endocan may be considered as an anti-ischemic treatment strategy in order to improve collateral development.

Endothelial and smooth muscle cells derived from human cardiac explants demonstrate angiogenic potential and suitable for design of cell-containing vascular grafts

Background

Endothelial and smooth muscle cells are considered promising resources for regenerative medicine and cell replacement therapy. It has been shown that both types of cells are heterogeneous depending on the type of vessels and organs in which they are located. Therefore, isolation of endothelial and smooth muscle cells from tissues relevant to the area of research is necessary for the adequate study of specific pathologies. However, sources of specialized human endothelial and smooth muscle cells are limited, and the search for new sources is still relevant. The main goal of our study is to demonstrate that functional endothelial and smooth muscle cells can be obtained from an available source—post-surgically discarded cardiac tissue from the right atrial appendage and right ventricular myocardium.

Methods

Heterogeneous primary cell cultures were enzymatically isolated from cardiac explants and then grown in specific endothelial and smooth muscle growth media on collagen IV-coated surfaces. The population of endothelial cells was further enriched by immunomagnetic sorting for CD31, and the culture thus obtained was characterized by immunocytochemistry, ultrastructural analysis and in vitro functional tests. The angiogenic potency of the cells was examined by injecting them, along with Matrigel, into immunodeficient mice. Cells were also seeded on characterized polycaprolactone/chitosan membranes with subsequent analysis of cell proliferation and function.

Results

Endothelial cells isolated from cardiac explants expressed CD31, VE-cadherin and VEGFR2 and showed typical properties, namely, cytoplasmic Weibel-Palade bodies, metabolism of acetylated low-density lipoproteins, formation of capillary-like structures in Matrigel, and production of extracellular matrix and angiogenic cytokines. Isolated smooth muscle cells expressed extracellular matrix components as well as α-actin and myosin heavy chain. Vascular cells derived from cardiac explants demonstrated the ability to stimulate angiogenesis in vivo. Endothelial cells proliferated most effectively on membranes made of polycaprolactone and chitosan blended in a 25:75 ratio, neutralized by a mixture of alkaline and ethanol. Endothelial and smooth muscle cells retained their functional properties when seeded on the blended membranes.

Conclusions

We established endothelial and smooth muscle cell cultures from human right atrial appendage and right ventricle post-operative explants. The isolated cells revealed angiogenic potential and may be a promising source of patient-specific cells for regenerative medicine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1156-1) contains supplementary material, which is available to authorized users.

Pharmacogenomics of heart failure: a systematic review

BACKGROUND

Heart failure (HF) and multiple HF-related phenotypes are heritable. Genes implicated in the HF pathophysiology would be expected to influence the response to treatment.

METHODS

We conducted a series of systematic literature searches on the pharmacogenetics of HF therapy to assess the current knowledge on this field.

RESULTS

Existing data related to HF pharmacogenomics are still limited. The ADRB1 gene is a likely candidate to predict response to β-blockers. Moreover, the cytochrome P450 2D6 coding gene (CYP2D6) clearly affects the pharmacokinetics of metoprolol, although the clinical impact of this association remains to be established.

CONCLUSION

Given the rising prevalence of HF and related costs, a more personalized use of HF drugs could have a remarkable benefit for patients, caregivers and healthcare systems.

Circulating Hepatocyte Growth Factor Level but Not Basic Fibroblast Growth Factor Level Is Elevated in Angiography-Proven Symptomatic Peripheral Artery Disease

Circulating vasogenic factors may be up-regulated in response to ischemia to promote angiogenesis in patients with peripheral artery disease (PAD). Studies on this are limited in number and size, and results are inconsistent, especially regarding basic fibroblast growth factor (bFGF) level. From March 1999 to April 2004, all consecutive patients with lower limb PAD having serum samples at the time of intervention were recruited. The diameter of the primary PAD lesion had to be at least 70% stenotic at the lower limb artery. Control subjects, who underwent angiography, were free of PAD, coronary disease, and other major medical diseases. Serum samples were analyzed for circulating hepatocyte growth factor (HGF) and bFGF levels. Patients with PAD (n = 60) had higher circulating HGF levels (mean ± SEM, 1544 ± 238 vs 970 ± 129 pg/mL; P = .04) but similar bFGF distribution tertiles (P = .55) compared with control subjects (n = 30). Thirty-six patients with summed PAD lesion lengths exceeding 5 cm demonstrated a significantly higher circulating HGF level compared with control subjects (mean ± SEM, 1701 ± 335 vs 970 ± 129 pg/mL; P = .048). Patients with concurrent coronary artery disease tend to have a higher circulating HGF level (mean ± SEM, 1606 ± 365 vs 970 ± 129 pg/mL; P = .06) but not a higher bFGF level compared with control subjects. Circulating HGF level, but not bFGF level, is significantly elevated in patients with symptomatic angiographically documented PAD, especially in those with more extensive involvement.

Collateral Growth in the Peripheral Circulation: A Review

Arterial occlusive diseases are a major cause of morbidity and death in the United States. The enlargement of pre-existing vessels, which bypass the site of arterial occlusion, provide a natural way for the body to compensate for such obstructions. Individuals differ in their capacity to develop collateral vessels. In recent years much attention has been focused upon therapy to promote collateral development, primarily using individual growth factors. Such studies have had mixed results. Persistent controversies exist regarding the initiating stimuli, the processes involved in enlargement, the specific vessels that should be targeted, and the most appropriate terminology. Consequently, it is now recognized that more research is needed to extend our knowledge of the complex process of collateral growth. This basic science review addresses five questions essential in understanding current problems in collateral growth research and the development of therapeutic interventions.

Vascular endothelial growth factor and hypoxia-inducible factor-1α gene polymorphisms and coronary collateral formation in patients with coronary chronic total occlusions

Introduction:

We evaluated the association between two single nucleotide polymorphisms of the vascular endothelial growth factor gene and one of the hypoxia-inducible factor-1α gene and the degree of coronary collateral formation in patients with a coronary chronic total occlusion.

Methods:

Totally, 98 patients with symptomatic coronary artery disease and a chronic total occlusion observed during coronary angiography were recruited. Genotyping of two vascular endothelial growth factor promoter single nucleotide polymorphisms (−152G>A and −165C>T) and the C1772T single nucleotide polymorphism of hypoxia-inducible factor-1α were performed using polymerase chain reaction and restriction fragment length polymorphism analysis. The presence and extent of collateral vessel filling was scored by blinded observers using the Rentrop grade.

Results:

We found no association between the vascular endothelial growth factor −152G>A, −165C>T and hypoxia-inducible factor-1α −1772C>T with the presence and filling of coronary collateral vessels. A history of percutaneous coronary intervention and transient ischaemic attack/cerebrovascular accident were associated with the presence of enhanced collateral vessel formation following binary logistic regression analysis.

Conclusion:

The study findings suggest that coronary collateral formation is not associated with the tested polymorphic variants of vascular endothelial growth factor and hypoxia-inducible factor-1α in patients with symptomatic coronary artery disease and the presence of a chronic total occlusion.

Vascular Regeneration in Ischemic Hindlimb by Adeno-Associated Virus Expressing Conditionally Silenced Vascular Endothelial Growth Factor

BACKGROUND

Critical limb ischemia (CLI) is the extreme manifestation of peripheral artery disease, a major unmet clinical need for which lower limb amputation is the only option for many patients. After 2 decades in development, therapeutic angiogenesis has been tested clinically via intramuscular delivery of proangiogenic proteins, genes, and stem cells. Efficacy has been modest to absent, and the largest phase 3 trial of gene therapy for CLI reported a worsening trend of plasmid fibroblast growth factor. In all clinical trials to date, gene therapy has used unregulated vectors with limited duration of expression. Only unregulated extended expression vectors such as adeno-associated virus (AAV) and lentivirus have been tested in preclinical models.

METHODS AND RESULTS

We present preclinical results of ischemia (hypoxia)-regulated conditionally silenced (CS) AAV-human vascular endothelial growth factor (hVEGF) gene delivery that shows efficacy and safety in a setting where other strategies fail. In a BALB/c mouse model of CLI, we show that gene therapy with AAV-CS-hVEGF, but not unregulated AAV or plasmid, vectors conferred limb salvage, protection from necrosis, and vascular regeneration when delivered via intramuscular or intra-arterial routes. All vector treatments conferred increased capillary density, but organized longitudinal arteries were selectively generated by AAV-CS-hVEGF. AAV-CS-hVEGF therapy reversibly activated angiogenic and vasculogenic genes, including Notch, SDF1, Angiopoietin, and Ephrin-B2. Reoxygenation extinguished VEGF expression and inactivated the program with no apparent adverse side effects.

CONCLUSIONS

Restriction of angiogenic growth factor expression to regions of ischemia supports the safe and stable reperfusion of hindlimbs in a clinically relevant murine model of CLI.

Applied Pathology for Interventions of Coronary Chronic Total Occlusion

Percutaneous coronary intervention of chronically occluded vessels can result in significant improvement in symptoms, relieve myocardial ischemia, and affect a reduction in major adverse cardiac events. Likelihood of achieving successful revascularization can be significantly enhanced with a thorough understanding of the pathology of these occluded coronary arteries. In this chapter, various steps and techniques to cross the CTO lesion and recanalize it are discussed in details.

Impact of obstructive sleep apnea in recruitment of coronary collaterality during inaugural acute myocardial infarction

BACKGROUND

Obstructive sleep apnea (OSA) may lead to myocardial preconditioning by increasing coronary collateral vessel recruitment in patients with acute coronary occlusion.

AIM

To determine the relationship between the severity of obstructive sleep apnea and coronary collaterality during acute myocardial infarction.

METHODS

This study prospectively included 71 patients with an inaugural myocardial infarction who had undergone a coronary angiography within 24h of onset. All patients underwent an overnight polygraph before discharge and were classified according to the apnea-hypopnea index (AHI). Coronary collaterals were scored by visual analyses and according to the Rentrop grading system.

RESULTS

Mean age was 59±11years and 83% of patients were men. All patients had complete or subtotal occlusion of the infarct-related artery. After the sleep study, patients were divided into two groups: 25 were suffering from OSA (AHI>15/h). Patients with OSA showed better collateral vessel development (Rentrop score≥1) compared to non-OSA patients (68 vs. 41%, P=0.032). AHI was significantly higher in patients with developed coronary collaterals (Rentrop≥1) compared to those without collaterality (17.74±13.2 vs. 12.24±10.9, P=0.025).

CONCLUSION

Coronary collateral development may be increased in OSA patients who are presenting with a first myocardial infarction.

CTO pathophysiology: how does this affect management?

Chronic total occlusion (CTO) pathophysiology has been described in a few, small studies using post mortem histology, and more recently, in vivo intravascular ultrasound (IVUS) to analyse the constituents of occluded segments. Recent improvements in equipment and techniques have revealed new insights into physical characteristics of occluded coronaries, which in turn enable predictable procedural success. The purpose of this review is to consider the published evidence describing CTO pathophysiology from the perspective of the hybrid algorithm approach to CTO PCI.

Methods: Literature searches using “Chronic Occlusion”, “angioplasty”, and” pathology” as keywords. Further searches on “coronary” “collateral”, “Viability”. Bibliographies were scrutinised for further key publications in an iterative process. Papers describing animal models were excluded.

Genetic variation: effect on prostate cancer

The crucial role of androgens in the development of prostate cancer is well established. The aim of this review is to examine the role of constitutional (germline) and tumor-specific (somatic) polymorphisms within important regulatory genes of prostate cancer. These include genes encoding enzymes of the androgen biosynthetic pathway, the androgen receptor gene, genes that encode proteins of the signal transduction pathways that may have a role in disease progression and survival, and genes involved in prostate cancer angiogenesis. Characterization of deregulated pathways critical to cancer cell growth have lead to the development of new treatments, including the CYP17 inhibitor abiraterone and clinical trials using novel drugs that are ongoing or recently completed [1]. The pharmacogenetics of the drugs used to treat prostate cancer will also be addressed. This review will define how germline polymorphisms are known affect a multitude of pathways, and therefore phenotypes, in prostate cancer etiology, progression, and treatment.

Regeneration through autologous hypoxia preconditioned plasma

Cellular hypoxic preconditioning is being employed to obtain complex, yet physiological, secretomes rich is angiogenic factors. We previously proposed exposing peripheral blood cells (PBCs) to hypoxic stress stimulation, and demonstrated that controlled release of PBC-derived factor mixtures induces directional microvessel growth in vitro. Hypoxia therefore provides a useful tool for enhancing the angiogenic potential of blood plasma, by generating compositions based on PBCs' natural responses to a wound-like microenvironment. Here, we discuss various methods for preparing and delivering Hypoxia Preconditioned Plasma (HPP), i.e., plasma derived after extracorporeal conditioning of anticoagulated blood under physiological temperature and hypoxia. Special emphasis is given to those approaches that will likely facilitate the clinical translation of HPP-based therapies. We finally draw a comparison between HPP and other, currently available blood-based products, and present the case that its arrival paves the way for developing next-generation autologous therapies toward angiogenesis-supported tissue repair and regeneration.

Predictors of poor coronary collateral development in patients with stable coronary artery disease: neutrophil-to-lymphocyte ratio and platelets

Objective:

The heterogeneity in the degree of collateralization among patients with coronary artery disease (CAD) remains incompletely understood. We evaluated the predictors of poorly developed coronary collateral circulation (CCC) in patients with stable coronary artery disease.

Methods:

Current study is a retrospective study, consisting of 118 patients with poor CCC and 130 patients with good CCC. We investigated predictors of poor coronary collaterals in a cohort of 248 patients who had high-grade coronary stenosis or occlusion on their angiograms. To classify CCC, we used the Rentrop classification.

Results:

Patients with poorly developed CCC had significantly higher neutrophil-to-lymphocyte ratio (N/L) compared with those with well-developed CCC, (4.2±2.8 vs. 3±3.1, p=0.001), whereas mean platelet volume, red cell distribution width and uric acid were not significantly different. Logistic regression analysis showed that N/L ratio (odds ratio 1.199, 95% confidence interval 1.045-1.375) and serum triglyceride levels [odds ratio (OR)=1.006, 95% confidence interval (CI)=1.001-1.010] were independent predictors of poorly developed CCC.

Conclusion:

An elevated level of N/L ratio is independently associated with a significant impairment in coronary collateralization. Our findings suggest that N/L ratio is an inexpensive, universally available hematological marker for sufficiency of CCC in patients with stable coronary artery disease.

VEGF and VEGFR genotyping in the prediction of clinical outcome for HCC patients receiving sorafenib: the ALICE-1 study

Although new treatment modalities changed the global approach to hepatocellular carcinoma (HCC), this disease still represents a medical challenge. Currently, the therapeutic stronghold is sorafenib, a tyrosine kinase inhibitor (TKI) directed against the vascular endothelial growth factor (VEGF) family. Previous observations suggested that polymorphisms of VEGF and its receptor (VEGFR) genes may regulate angiogenesis and lymphangiogenesis and thus tumour growth control. The aim of our study was to evaluate the role of VEGF and VEGFR polymorphisms in determining the clinical outcome of HCC patients receiving sorafenib. From a multicentre experience 148 samples (tumour or blood samples) of HCC patients receiving sorafenib were tested for VEGF-A, VEGF-C and VEGFR-1,2,3 single nucleotide polymorphisms (SNPs). Patients' progression-free survival (PFS) and overall survival (OS) were analysed. At univariate analysis VEGF-A alleles C of rs25648, T of rs833061, C of rs699947, C of rs2010963, VEGF-C alleles T of rs4604006, G of rs664393, VEGFR-2 alleles C of rs2071559, C of rs2305948 were significant predictors of PFS and OS. At multivariate analysis rs2010963, rs4604006 and BCLC (Barcelona Clinic Liver Cancer) stage resulted to be independent factors influencing PFS and OS. Once prospectively validated, the analysis of VEGF and VEGFR SNPs may represent a clinical tool to better identify HCC patients more likely to benefit from sorafenib. On the other hand, the availability of more accurate predictive factors could help avoiding unnecessary toxicities to potentially resistant patients who may be optimal candidates for different treatments interfering with other tumour molecular pathways.

Association of genetic variants in VEGF-A with clinical recurrence in prostate cancer patients treated with definitive radiotherapy

BACKGROUND AND PURPOSE

Vascular endothelial growth factor-A (VEGF-A), a key regulator of tumor-induced angiogenesis, is critical for tumor growth and metastasization. The goal of the present study was to evaluate the prognostic value of VEGF single nucleotide polymorphisms (SNPs) and haplotypes for clinical recurrence after definitive radiotherapy for prostate cancer.

PATIENTS AND METHODS

The association of seven VEGF-A polymorphisms and their haplotypes with clinical recurrence (defined as the occurrence of local recurrence and/or distant metastases) in 496 prostate cancer patients treated with definitive radiotherapy were investigated. Genotypes were determined by 5'-nuclease (TaqMan) assays; haplotypes were analyzed using the Haploview program.

RESULTS

Within a median follow-up time of 80 months, 44 patients (9 %) developed clinical recurrences. Haplotype analysis showed two separate blocks of high-linkage disequilibrium, formed by five polymorphisms (- 2578C > A, - 2489C > T, - 1498C > T, - 634G > C, - 7C > T) upstream of the coding sequence (CCCCC, ATTGC, CCCGC, ATTGT) and two polymorphisms (936C > T, 1612G > A) downstream of the coding sequence (CA, CG, TG). Carriers of at least 1 copy of the ATTGC haplotype were at higher risk of recurrence (hazard ratio [HR] 3.83; 95 %CI 1.48-9.90, p = 0.006); for carriers of 2 copies, the HR was 4.85 (95 %CI 1.72-13.6; p = 0.003). In multivariate analysis, patients harboring at least one copy of the ATTGC haplotype remained at increased risk of recurrence (HR 3.63, 95 %CI 1.38-9.55, p = 0.009); in patients carrying 2 copies, the HR was 4.72 (95 %CI 1.64-13.6, p = 0.004).

CONCLUSION

Our findings indicate that the VEGF-A ATTGC haplotype may predict clinical recurrence in prostate cancer patients treated with radiotherapy.

PHD2 regulates arteriogenic macrophages through TIE2 signalling

Occlusion of the main arterial route redirects blood flow to the collateral circulation. We previously reported that macrophages genetically modified to express low levels of prolyl hydroxylase domain protein 2 (PHD2) display an arteriogenic phenotype, which promotes the formation of collateral vessels and protects the skeletal muscle from ischaemic necrosis. However, the molecular mechanisms underlying this process are unknown. Here, we demonstrate that femoral artery occlusion induces a switch in macrophage phenotype through angiopoietin-1 (ANG1)-mediated Phd2 repression. ANG blockade by a soluble trap prevented the downregulation of Phd2 expression in macrophages and their phenotypic switch, thus inhibiting collateral growth. ANG1-dependent Phd2 repression initiated a feed-forward loop mediated by the induction of the ANG receptor TIE2 in macrophages. Gene silencing and cell depletion strategies demonstrate that TIE2 induction in macrophages is required to promote their proarteriogenic functions, enabling collateral vessel formation following arterial obstruction. These results indicate an indispensable role for TIE2 in sustaining in situ programming of macrophages to a proarteriogenic, M2-like phenotype, suggesting possible new venues for the treatment of ischaemic disorders.

Obstructive sleep apnea and coronary artery disease: from pathophysiology to clinical implications

Coronary artery disease (CAD) and obstructive sleep apnea (OSA) are both complex and significant clinical problems. The pathophysiological mechanisms that link OSA with CAD are complex and can influence the broad spectrum of conditions caused by CAD, from subclinical atherosclerosis to myocardial infarction. OSA remains a significant clinical problem among patients with CAD, and evidence suggesting its role as a risk factor for CAD is growing. Furthermore, increasing data support that CAD prognosis may be influenced by OSA and its treatment by continuous positive airway pressure (CPAP) therapy. However, stronger evidence is needed to definitely answer these questions. This paper focuses on the relationship between OSA and CAD from the pathophysiological effects of OSA in CAD, to the clinical implications of OSA and its treatment in CAD patients.

Attenuation of hind-limb ischemia in mice with endothelial-like cells derived from different sources of human stem cells

Functional endothelial-like cells (EC) have been successfully derived from different cell sources and potentially used for treatment of cardiovascular diseases; however, their relative therapeutic efficacy remains unclear. We differentiated functional EC from human bone marrow mononuclear cells (BM-EC), human embryonic stem cells (hESC-EC) and human induced pluripotent stem cells (hiPSC-EC), and compared their in-vitro tube formation, migration and cytokine expression profiles, and in-vivo capacity to attenuate hind-limb ischemia in mice. Successful differentiation of BM-EC was only achieved in 1/6 patient with severe coronary artery disease. Nevertheless, BM-EC, hESC-EC and hiPSC-EC exhibited typical cobblestone morphology, had the ability of uptaking DiI-labeled acetylated low-density-lipoprotein, and binding of Ulex europaeus lectin. In-vitro functional assay demonstrated that hiPSC-EC and hESC-EC had similar capacity for tube formation and migration as human umbilical cord endothelial cells (HUVEC) and BM-EC (P>0.05). While increased expression of major angiogenic factors including epidermal growth factor, hepatocyte growth factor, vascular endothelial growth factor, placental growth factor and stromal derived factor-1 were observed in all EC cultures during hypoxia compared with normoxia (P<0.05), the magnitudes of cytokine up-regulation upon hypoxic were more dramatic in hiPSC-EC and hESC-EC (P<0.05). Compared with medium, transplanting BM-EC (n = 6), HUVEC (n = 6), hESC-EC (n = 8) or hiPSC-EC (n = 8) significantly attenuated severe hind-limb ischemia in mice via enhancement of neovascularization. In conclusion, functional EC can be generated from hECS and hiPSC with similar therapeutic efficacy for attenuation of severe hind-limb ischemia. Differentiation of functional BM-EC was more difficult to achieve in patients with cardiovascular diseases, and hESC-EC or iPSC-EC are readily available as "off-the-shelf" format for the treatment of tissue ischemia.

Changes of serum angiogenic factors concentrations in patients with diabetes and unstable angina pectoris

Backgroud

Diabetic microvascular changes are considered to be influenced by angiogenic factors. As a compensatory mechanism, the expression of some angiogenic factors are elevated in ischemic myocardium. The aim of this study was to investigate the changes of serum angiogenic factors, and the association among these angiogenic factors, the severity of coronary artery stenosis and collateral vessels form in patients with diabetes and unstable angina pectoris (UAP).

Methods

42 patients with diabetes (diabetes group), 57 patients with UAP (UAP group), and 36 age-matched healthy people (control group) were selected. Serum concentrations of angiogenic factors were measured using cytokine array technology. The severity of coronary artery stenosis was scored using the angiographic Gensini score. Coronary collateral vessels were scored according to Rentrop's classification.

Results

No significant differences in the serum concentrations of vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), angiogenin, angiostatin, basic fibroblast growth factor (bFGF) and platelet-derived growth factor-BB (PDGF-BB) were detected between control group and diabetes group. But in patients with diabetes complicated with UAP and in patients with UAP without diabetes, serum concentrations of VEGF and Ang-2 were elevated (p < 0.01, p < 0.01). Only serum Ang-2 concentrations were significantly correlated with Gensini score (r=0.585, p < 0.001), left ventricular end diastolic diameter (r=0.501, p < 0.001), left ventricular end systolic diameter (r=0.563, p < 0.001) and left ventricular ejection fraction (r=−0.523, p < 0.001).

Conclusion

Serum concentrations of VEGF and Ang-2 were increased, and diabetes didn’t affect this increases in patients with UAP. Serum Ang-2 concentrations were correlated with the severity of coronary artery stenosis.

Prevalence of +405G>C,-1154G>A Vascular Endothelial Growth Factor Polymorphism in Breast Cancer

Vascular endothelial growth factor (VEGF) plays an important role in the development of Breast Cancer. The aim of this study was to investigate the association of polymorphisms in the VEGF gene on prognosis of Breast Cancer patients. This study comprised 200 patients with histologically confirmed cases of Breast cancer and 200 controls. Genotyping of the VEGF gene polymorphisms at +405G>C,-1154G>A, were performed by PCR-RFLP analysis. Preoperative plasma VEGF levels were determined by ELISA. Amongst both cases and controls, the genotypic distribution of the individual SNPs were all in Hardy-Weinberg equilibrium. Mean VEGF level was significantly elevated in cases compared to controls (t = 8.248; P < 0.001). No significant association was found between +405G>C,-1154G>A VEGF polymorphism and Breast Cancer. Logistic regression analysis revealed that 405GG & 1154GG were associated with higher levels of VEGF.

Mechanistic, technical, and clinical perspectives in therapeutic stimulation of coronary collateral development by angiogenic growth factors

Stimulation of collateral vessel development in the heart by angiogenic growth factor therapy has been tested in animals and humans for almost two decades. Discordance between the outcome of preclinical studies and clinical trials pointed to the difficulties of translation from animal models to patients. Lessons learned in this process identified specific mechanistic, technical, and clinical hurdles, which need to be overcome. This review summarizes current understanding of the mechanisms leading to the establishment of a functional coronary collateral network and the biological processes growth factor therapies should stimulate even under conditions of impaired natural adaptive vascular response. Vector delivery methods are recommended to maximize angiogenic gene therapy efficiency and reduce side effects. Optimization of clinical trial design should include the choice of clinical end points which provide mechanistic proof-of-concept and also reflect clinical benefits (e.g., surrogates to assess increased collateral flow reserve, such as myocardial perfusion imaging). Guidelines are proposed to select patients who may respond to the therapy with high(er) probability. Both short and longer term strategies are outlined which may help to make therapeutic angiogenesis (TA) work in the future.

VEGF and VEGFR polymorphisms affect clinical outcome in advanced renal cell carcinoma patients receiving first-line sunitinib

Background:

Currently, sunitinib represents one of the therapeutic strongholds for renal cell carcinoma, but the criteria for treatment selection are lacking. We assessed the role of vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) polymorphisms in the prediction of the clinical outcome in metastatic renal cell carcinoma (mRCC) patients.

Methods:

A total of 84 tumour samples from mRCC patients receiving first-line sunitinib were tested for VEGF and VEGFR single-nucleotide polymorphisms (SNPs). The SNP results were correlated with progression-free survival (PFS) and overall survival (OS).

Results:

Median PFS was 8.22 months, although whereas median OS was 32.13 months. The VEGF A rs833061 resulted significant in PFS (17 vs 4 months; P<0.0001) and OS (38 vs 10 months; P<0.0001). The VEGF A rs699947 was significant for PFS (18 vs 4 months; P=0.0001) and OS (37 vs 16 months; P<0.0001). The VEGF A rs2010963 was significant in PFS (18 vs 8 vs 2 months; P=0.0001) and OS (31 vs 36 vs 9 months; P=0.0045). The VEGR3 rs6877011 was significant in PFS (12 vs 4 months; P=0.0075) and OS (36 vs 17 months; P=0.0001). At multivariate analysis, rs833061, rs2010963 and rs68877011 were significant in PFS, and rs833061 and rs68877011 were independent factors in OS.

Conclusions:

In our analysis, patients with TT polymorphism of rs833061, CC polymorphism of rs699947, CC polymorphism of rs2010963 and CG polymorphism of rs6877011 seem to have a worse PFS and OS when receiving first-line sunitinib.

Hypoxia-induced angiogenesis: good and evil

The vascular network delivers oxygen (O(2)) and nutrients to all cells within the body. It is therefore not surprising that O(2) availability serves as a primary regulator of this complex organ. Most transcriptional responses to low O(2) are mediated by hypoxia-inducible factors (HIFs), highly conserved transcription factors that control the expression of numerous angiogenic, metabolic, and cell cycle genes. Accordingly, the HIF pathway is currently viewed as a master regulator of angiogenesis. HIF modulation could provide therapeutic benefit for a wide array of pathologies, including cancer, ischemic heart disease, peripheral artery disease, wound healing, and neovascular eye diseases. Hypoxia promotes vessel growth by upregulating multiple pro-angiogenic pathways that mediate key aspects of endothelial, stromal, and vascular support cell biology. Interestingly, recent studies show that hypoxia influences additional aspects of angiogenesis, including vessel patterning, maturation, and function. Through extensive research, the integral role of hypoxia and HIF signaling in human disease is becoming increasingly clear. Consequently, a thorough understanding of how hypoxia regulates angiogenesis through an ever-expanding number of pathways in multiple cell types will be essential for the identification of new therapeutic targets and modalities.

Altitude and the risk of cardiovascular events in incident US dialysis patients

BACKGROUND

Altitude is associated with all-cause mortality in US dialysis patients, but its association with cardiovascular outcomes has not been assessed. We hypothesized that higher altitude would be associated with lower rates of cardiovascular events due to an altered physiological response of dialysis patients to altitude induced hypoxia.

METHODS

We studied 984,265 patients who initiated dialysis from 1995 to 2006. Patients were stratified by the mean elevation of their residential zip codes and were followed from the start of dialysis to the occurrence of several validated cardiovascular endpoints: myocardial infarction, stroke, cardiovascular death and a composite of these end points. Incidence rate ratios across altitude strata were estimated using proportional hazards regression.

RESULTS

All outcomes occurred less frequently among patients living at higher altitude compared with patients living at or near sea level, and the association appeared monotonic for all outcomes except for stroke, which was most incident in the 250-1999 ft group. Compared with otherwise similar patients residing at or near sea level, patients living at ≥ 6000 ft had 31% [95% confidence interval (CI): 21-41%] lower rates of myocardial infarction, 27% (95% CI: 15-37%) lower rates of stroke and 19% (95% CI: 14-24%) lower rates of cardiovascular death. Additional adjustment for biometric information did not materially change these findings. Effect modification between race and altitude was only consistently significant for Native Americans. Altitude did not significantly alter the rates of non-cardiovascular death.

CONCLUSION

We conclude that dialysis patients at higher altitude experience lower rates of cardiovascular events compared to otherwise similar patients at lower altitude.

VEGFA and VEGFR2 genetic polymorphisms and survival in patients with diffuse large B cell lymphoma

We evaluated the impact of functional polymorphisms in the vascular endothelial growth factor A (VEGFA) and vascular endothelial growth factor 2 (VEGFR2) genes on the survival of patients with diffuse large B cell lymphoma (DLBCL). Five potentially functional polymorphisms in the VEGFA (rs699947, rs2010963 and rs3025039) and VEGFR2 (rs1870377 and rs2305948) genes were assessed in 494 DLBCL patients treated with rituximab plus CHOP chemotherapy. The associations of genotype and haplotype with overall survival (OS) and progression-free survival (PFS) were analyzed. Of the five polymorphisms, VEGFR2 rs1870377T>A was significantly associated with both OS and PFS; in the dominant model, patients with the AA + TA genotypes had significantly better OS (P = 0.002) and PFS (P = 0.004) than those with the TT genotype. The association between significantly better OS and the AA + TA genotypes was observed separately in patients with low (0-2; P = 0.035) and high (3-5; P = 0.043) International Prognostic Index scores. Multivariate analysis showed that, relative to the AA + TA genotypes, the TT genotype was an independent prognostic factor for poor OS (HR, 1.71; 95% CI, 1.21-2.43; P = 0.002) and PFS (HR, 1.57; 1.13-2.17; P = 0.004). Other independent significant predictors of survival in patients with DLBCL were International Prognostic Index score, age > 60 years, lactate dehydrogenase concentration >normal, extranodal disease >1 and presence of B symptoms. The VEGFR2 rs1870377 polymorphism might affect survival in patients with DLBCL, suggesting that angiogenesis might be related to poor survival in these patients.

Study on the role of environmental parameters and HIF-1A gene polymorphism in coronary collateral formation among patients with ischemic heart disease

OBJECTIVES

To evaluate the association between collateral formation and some environmental factors along with a polymorphism in HIF-1A gene in selected Iranian patients with CAD.

DESIGN AND METHODS

Patients with ≥ 70% narrowing in at least one coronary vessel according to coronary angiography were enrolled. The patients' demographic, clinical and biochemical data were collected. The presence of C1772T polymorphisms within HIF-1A was analyzed using the polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP).

RESULTS

There is no significant difference between the patients with and without collaterals according to the frequency of T allele or HIF-1A variants. The higher severity of coronary vessel obstruction was positive predictor of collateral formation (OR=1.026, 95%, CI: 1.02-0.04, p<0.001), whereas aging and cigarette smoking were negative predictors (OR=0.95, 95% CI: 0.91-0.99, p<0.05; OR=0.30, 95% CI: 0.11-0.79, p <0.05; respectively).

CONCLUSIONS

The findings indicate not any significant association between collateral formation and polymorphic variants of HIF-1A and P582S substitution does not appear to influence the collateral formation in patients with myocardial ischemia.