Ian Buysschaert

HRG Inhibits Tumor Growth and Metastasis by Inducing Macrophage Polarization and Vessel Normalization through Downregulation of PlGF

Polarization of tumor-associated macrophages (TAMs) to a proangiogenic/immune-suppressive (M2-like) phenotype and abnormal, hypoperfused vessels are hallmarks of malignancy, but their molecular basis and interrelationship remains enigmatic. We report that the host-produced histidine-rich glycoprotein (HRG) inhibits tumor growth and metastasis, while improving chemotherapy. By skewing TAM polarization away from the M2- to a tumor-inhibiting M1-like phenotype, HRG promotes antitumor immune responses and vessel normalization, effects known to decrease tumor growth and metastasis and to enhance chemotherapy. Skewing of TAM polarization by HRG relies substantially on downregulation of placental growth factor (PlGF). Besides unveiling an important role for TAM polarization in tumor vessel abnormalization, and its regulation by HRG/PlGF, these findings offer therapeutic opportunities for anticancer and antiangiogenic treatment.

Vitamin D deficiency is highly prevalent in COPD and correlates with variants in the vitamin D-binding gene

Introduction Vitamin D deficiency has been associated with many chronic illnesses, but little is known about its relationship with chronic obstructive pulmonary disease (COPD). Objectives Serum 25-hydroxyvitamin D (25-OHD) levels were measured in 414 (ex)-smokers older than 50 years and the link between vitamin D status and presence of COPD was assessed. The rs7041 and rs4588 variants in the vitamin D-binding gene (GC) were genotyped and their effects on 25-OHD levels were tested. Results In patients with COPD, 25-OHD levels correlated significantly with forced expiratory volume in 1 s (FEV1) (r=0.28, p<0.0001). Compared with 31% of the smokers with normal lung function, as many as 60% and 77% of patients with GOLD (Global Initiative for Obstructive Lung Disease) stage 3 and 4 exhibited deficient 25-OHD levels <20 ng/ml (p<0.0001). Additionally, 25-OHD levels were reduced by 25% in homozygous carriers of the rs7041 at-risk T allele (p<0.0001). This correlation was found to be independent of COPD severity, smoking history, age, gender, body mass index, corticosteroid intake, seasonal variation and rs4588 (p<0.0001). Notably, 76% and 100% of patients with GOLD stage 3 and 4 homozygous for the rs7041 T allele exhibited 25-OHD levels <20 ng/ml. Logistic regression corrected for age, gender and smoking history further revealed that homozygous carriers of the rs7041 T allele exhibited an increased risk for COPD (OR 2.11; 95% CI 1.20 to 3.71; p=0.009). Conclusion Vitamin D deficiency occurs frequently in COPD and correlates with severity of COPD. The data warrant vitamin D supplementation in patients with severe COPD, especially in those carrying at-risk rs7041 variants.

Underestimated and under-recognized: the late consequences of acute coronary syndrome (GRACE UK–Belgian Study)

AIM To define the long-term outcome of patients presenting with acute coronary syndrome [ST-segment elevation myocardial infarction (STEMI), and non-STEMI and unstable angina acute coronary syndrome (ACS) without biomarker elevation] and to test the hypothesis that the GRACE (Global Registry of Acute Coronary Events) risk score predicts mortality and death/MI at 5 years. METHODS AND RESULTS In the GRACE long-term study, UK and Belgian centres prospectively recruited and followed ACS patients for a median of 5 years (1797 days). Primary outcome events: deaths, cardiovascular deaths (CVDs) and MIs. Secondary events: stroke and re-hospitalization for ACS. There were 736 deaths, 19.8% (482 CVDs, 13%) and 347 (9.3%) MIs (>24 h), 261 strokes (7.7%), and 452 (17%) subsequent revascularizations. Rehospitalization was common: average 1.6 per patient; 31.2% had >1 admission, 9.2% had 5+ admissions. These events were despite high rates of guideline indicated therapies. The GRACE score was highly predictive of all-cause death, CVD, and CVD/MI at 5 years (death: χ(2) likelihood ratio 632; Wald 709.9, P< 0.0001, C-statistic 0.77; for CVD C-statistic 0.75, P < 0.0001; CVD/MI C-statistic 0.70, P < 0.0001). Compared with the low-risk GRACE stratum (ESC Guideline criteria), those with intermediate [hazard ratio (HR) 2.14, 95% CI 1.63, 2.81] and those with high-risk (HR 6.36, 95% CI 4.95, 8.16) had two- and six-fold higher risk of later death (Cox proportional hazard). A landmark analysis after 6 months confirmed that the GRACE score predicted long-term death (χ(2) likelihood ratio 265.4; Wald 289.5, P < 0.0001). Although in-hospital rates of death and MI are higher following STEMI, the cumulative rates of death (and CVD) were not different, by class of ACS, over the duration of follow-up (Wilcoxon = 1.5597, df = 1, P = 0.21). At 5 years after STEMI 269/1403 (19%) died; after non-STEMI 262/1170 (22%) after unstable angina (UA) 149/850 (17%). Two-thirds (68%) of STEMI deaths occurred after initial hospital discharge, but this was 86% for non-STEMI and 97% for UA. CONCLUSION The GRACE risk score predicts early and 5 year death and CVD/MI. Five year morbidity and mortality are as high in patients following non-ST MI and UA as seen following STEMI. Their morbidity burden is high (MI, stroke, readmissions) and the substantial late mortality in non-STE ACS is under-recognized. The findings highlight the importance of pursuing novel approaches to diminish long-term risk.

Further pharmacological and genetic evidence for the efficacy of PlGF inhibition in cancer and eye disease.

Our findings that PlGF is a cancer target and anti-PlGF is useful for anticancer treatment have been challenged by Bais et al. Here we take advantage of carcinogen-induced and transgenic tumor models as well as ocular neovascularization to report further evidence in support of our original findings of PlGF as a promising target for anticancer therapies. We present evidence for the efficacy of additional anti-PlGF antibodies and their ability to phenocopy genetic deficiency or silencing of PlGF in cancer and ocular disease but also show that not all anti-PlGF antibodies are effective. We also provide additional evidence for the specificity of our anti-PlGF antibody and experiments to suggest that anti-PlGF treatment will not be effective for all tumors and why. Further, we show that PlGF blockage inhibits vessel abnormalization rather than density in certain tumors while enhancing VEGF-targeted inhibition in ocular disease. Our findings warrant further testing of anti-PlGF therapies.

The 15q24/25 Susceptibility Variant for Lung Cancer and Chronic Obstructive Pulmonary Disease Is Associated with Emphysema

RATIONALE Genome-wide association studies have identified genetic variants in the nicotinic acetylcholine receptor (nAChR) on chromosome 15q24/25 as a risk for nicotine dependence, lung cancer, and chronic obstructive pulmonary disease (COPD). Assessment of bronchial obstruction by spirometry, typically used for diagnosing COPD, fails, however, to detect emphysema. OBJECTIVES To determine the association of the 15q24/25 locus with emphysema. METHODS The rs1051730 variant on 15q24/25 was genotyped in two independent white cohorts of 661 and 456 heavy smokers. Participants underwent pulmonary function tests and computed tomography (CT) of the chest, and took questionnaires assessing smoking behavior and health status. MEASUREMENTS AND MAIN RESULTS The rs1051730 A-allele correlated with reduced FEV(1) and with increased susceptibility for bronchial obstruction with a pooled odds ratio (OR) of 1.33 (95% confidence interval [CI] = 1.11-1.61; P = 0.0026). In both studies a correlation between the rs1051730 A-allele and lung diffusing capacity (Dl(CO)) and diffusing capacity per unit alveolar volume (Kco) was observed. Consistently, the rs1051730 A-allele conferred increased risk for emphysema as assessed by CT (P = 0.0097 and P = 0.019), with a pooled OR of 1.39 (CI = 1.15-1.68; P = 0.00051). Visual emphysema scores and scores based on densities quantified on CT were more pronounced in A-allele carriers, indicating that rs1051730 correlates with the severity of emphysema. CONCLUSIONS The 15q24/25 locus in nAChR is associated with the presence and severity of emphysema. This association was independent of pack-years smoking, suggesting that nAChR is causally involved in alveolar destruction as a potentially shared pathogenic mechanism in lung cancer and COPD.

The Association of the 4q25 Susceptibility Variant for Atrial Fibrillation With Stroke Is Limited to Stroke of Cardioembolic Etiology

Background and Purpose— Genome-wide association studies recently identified 2 variants on chromosome 4q25 as susceptibility factors for atrial fibrillation. Interestingly, these variants were subsequently also shown to be associated with stroke. However, it remains unclear whether 4q25 associates with all the stroke subtypes or with cardioembolic stroke in particular, which is often attributable to atrial fibrillation. Methods— We performed a large case-control association study in 4199 ischemic stroke patients, all subtyped according to Trial of Org 10172 in Acute Stroke Treatment criteria, and 3750 controls derived from 6 studies conducted in Australia, Austria, Belgium, Poland, Spain, and Sweden. Two variants on chromosome 4q25, rs1906591 and rs10033464, were genotyped. Results— Within cases, the A-allele of rs1906591 was associated with atrial fibrillation (odds ratio, 1.64 [95% CI, 1.43 to 1.90]; P=9.2 · 10−12), whereas rs10033464 was only marginally associated. There was an association between overall ischemic stroke and rs1906591 (odds ratio, 1.20 [95% CI, 1.09 to 1.32]; P=1.2 · 10−4). However, this was probably caused by the large effect of stroke of cardioembolic etiology because no relation was obtained in any other subgroup of stroke. The rs10033464 variant failed to show any relationship with ischemic stroke. Conclusions— We replicated the association of the rs1906591 variant on chromosome 4q25 with atrial fibrillation and ischemic stroke of cardioembolic etiology. The 4q25 locus failed to associate with noncardiac subtypes of ischemic stroke.

A variant at chromosome 9p21 is associated with recurrent myocardial infarction and cardiac death after acute coronary syndrome: the GRACE Genetics Study

AIMS Recent genetic studies identified the rs1333049 variant on chromosome 9p21 as a major susceptibility locus for coronary artery disease and myocardial infarction (MI). Here, we evaluated whether this variant also contributes to recurrent MI or cardiac death following an acute coronary syndrome (ACS). METHODS AND RESULTS A total of 3247 patients with ACS enrolled in the Global Registry of Acute Coronary Events (GRACE) in three distinct populations (UK, Belgium and Poland) were prospectively followed for 6 months and genotyped for rs1333049, in addition to 3004 and 2467 healthy controls from the UK and Belgium. After having confirmed that the at-risk C allele of rs1333049 was associated with index ACS in the UK and Belgian populations, we found that the rs1333049 at-risk C allele was significantly and independently associated with recurrent MI [age- and gender-adjusted hazard ratio (HR) 1.48, CI = 1.00-2.19, P = 0.048; and multivariable-adjusted HR 1.47, CI = 0.99-2.18; P = 0.053] and with recurrent MI or cardiac death (age- and gender-adjusted HR 1.58, CI = 1.00-2.48; P = 0.045; and multivariable adjusted HR 1.49, CI = 1.03-1.98; P = 0.028) within 6 months after an index ACS. Inclusion of rs1333049 into the GRACE risk score significantly improved classification for recurrent MI or cardiac death (P = 0.040), as calculated by the integrated discrimination improvement method. CONCLUSION In this large observational study, the 9p21 variant was independently associated with adverse cardiac outcome after ACS.

Short-term delivery of anti-PlGF antibody delays progression of atherosclerotic plaques to vulnerable lesions

AIMS Placental growth factor (PlGF), a homologue of vascular endothelial growth factor, is a pleiotropic cytokine with a pro-inflammatory activity. Previous gene-inactivation studies revealed that the loss of PlGF delays atherosclerotic lesion development and inhibits macrophage infiltration, but the activity of an anti-PlGF antibody (alphaPlGF mAb) has not been evaluated yet. METHODS AND RESULTS We characterized the potential of short-term delivery of alphaPlGF mAb in inhibiting lesion development in ApoE-deficient mice (apoE(-/-)) and in CD4:TGFbetaRII(DN) x apoE(-/-) mice, a more severe atherosclerosis model. Short-term treatment of alphaPlGF mAb reduces early atherosclerotic plaque size and inflammatory cell infiltration in the lesion. CONCLUSION These pharmacological alphaPlGF mAb results confirm previous genetic evidence that inhibition of PlGF slows down early atherosclerotic lesion development. Furthermore, the phenocopy of genetic and pharmacological loss-of-function strategies underscores that alphaPlGF acts by selectively neutralizing PlGF.

Neuronal FLT1 receptor and its selective ligand VEGF-B protect against retrograde degeneration of sensory neurons

Even though VEGF‐B is a homologue of the potent angiogenic factor VEGF, its angiogenic activities have been controversial. Intrigued by findings that VEGF‐B may also affect neuronal cells, we assessed the neuroprotective and vasculoprotective effects of VEGF‐B in the skin, in which vessels and nerves are functionally intertwined. Although VEGF‐B and its FLT1 receptor were prominently expressed in dorsal root ganglion (DRG) neurons innervating the hindlimb skin, they were not essential for nerve function or vascularization of the skin. However, primary DRG cultures lacking VEGF‐B or FLT1 exhibited increased neuronal stress and were more susceptible to paclitaxel‐induced cell death. Concomitantly, mice lacking VEGF‐B or a functional FLT1 developed more retrograde degeneration of sensory neurons in a model of distal neuropathy. On the other hand, the addition of the VEGF‐B isoform, VEGF‐B186, to DRG cultures antagonized neuronal stress, maintained the mitochon‐drial membrane potential and stimulated neuronal survival. Mice overexpressing VEGF‐B186 or FLT1 selectively in neurons were protected against the distal neuropathy, whereas exogenous VEGF‐B186, either delivered by gene transfer or as a recombinant factor, was protective by directly affecting sensory neurons and not the surrounding vasculature. Overall, this indicates that VEGF‐B, instead of acting as an angiogenic factor, exerts direct neuroprotective effects through FLT1. These findings also suggest a clinically relevant role for VEGF‐B in preventing distal neuropathies.—Dhondt, J., Peeraer, E., Verheyen, A., Nuydens, R., Buysschaert, I., Poesen, K., Van Geyte, K., Beerens, M., Shibuya, M., Haigh, J. J., Meert, T., Carmeliet, P., Lambrechts, D. Neuronal FLT1 receptor and its selective ligand VEGF‐B protect against retrograde degeneration of sensory neurons. FASEB J. 25, 1461–1473 (2011). www.fasebj.org

Genetics, epigenetics and pharmaco‐(epi)genomics in angiogenesis

•  Introduction •  Angiogenesis is genetically pre‐determined •  Mutations causing vascular anomalies ‐  Venous anomalies ‐  Haemangiomas ‐  The transforming growth factor‐ß in vascular anomalies ‐  Cerebral cavernous malformations •  Translocations reveal novel angiogenic genes •  Single nucleotide polymorphisms shape the angio‐genome ‐  SNPs in VEGF and their association with cancer ‐  SNPs in VEGF pathway genes associated with other diseases ‐  Genetic variability in VEGFR‐2 ‐  Genetic variability in HIF‐1α ‐  SNPs in VEGFR‐1 integrate angiogenesis within the P53 pathway ‐  Variations in angiogenic genes are linked with neurodegeneration ‐  Angiogenic factors in genome‐wide association studies •  Copy number variability affects angiogenesis •  Epigenetic regulation of angiogenesis ‐  Methylation of anti‐angiogenic factors ‐  Methylation as a second hit event in cancer ‐  Histone modifications determine angiogenesis •  Micromanagers of angiogenesis •  Perspectives