Kidney Tissue Proteome Profiles in Short Versus Long Duration of Delayed Graft Function - A Pilot Study in Donation After Circulatory Death Donors

Introduction

Delayed graft function (DGF) is often defined as the need for dialysis treatment in the first week after a kidney transplantation. This definition, though readily applicable, is generic and unable to distinguish between "types" of DGF or time needed to recover function that may also significantly affect longer-term outcomes. We aimed to profile biological pathways in donation after circulatory death (DCD) kidney donors that correlate with DGF and different DGF durations.

Methods

A total of N = 30 DCD kidney biopsies were selected from the UK Quality in Organ Donation (QUOD) biobank and stratified according to DGF duration (immediate function, IF n = 10; "short-DGF" (1-6 days), SDGF n = 10; "long-DGF" (7-22 days), LDGF n = 10). Samples were matched for donor and recipient demographics and analyzed by label-free quantitative (LFQ) proteomics, yielding identification of N = 3378 proteins.

Results

Ingenuity pathway analysis (IPA) on differentially abundant proteins showed that SDGF kidneys presented upregulation of stress response pathways, whereas LDGF presented impaired response to stress, compared to IF. LDGF showed extensive metabolic deficits compared to IF and SDGF.

Conclusion

DCD kidneys requiring dialysis only in the first week posttransplant present acute cellular injury at donation, alongside repair pathways upregulation. In contrast, DCD kidneys requiring prolonged dialysis beyond 7 days present minimal metabolic and antioxidant responses, suggesting that current DGF definitions might not be adequate in distinguishing different patterns of injury in donor kidneys contributing to DGF.

Proteomic prediction of incident heart failure and its main subtypes

AIM

To examine the ability of serum proteins in predicting future heart failure (HF) events, including HF with reduced or preserved ejection fraction (HFrEF or HFpEF), in relation to event time, and with or without considering established HF-associated clinical variables.

METHODS AND RESULTS

In the prospective population-based Age, Gene/Environment Susceptibility Reykjavik Study (AGES-RS), 440 individuals developed HF after their first visit with a median follow-up of 5.45 years. Among them, 167 were diagnosed with HFrEF and 188 with HFpEF. A least absolute shrinkage and selection operator regression model with non-parametric bootstrap were used to select predictors from an analysis of 4782 serum proteins, and several pre-established clinical parameters linked to HF. A subset of 8-10 distinct or overlapping serum proteins predicted different future HF outcomes, and C-statistics were used to assess discrimination, revealing proteins combined with a C-index of 0.80 for all incident HF, 0.78 and 0.80 for incident HFpEF or HFrEF, respectively. In the AGES-RS, protein panels alone encompassed the risk contained in the clinical information and improved the performance characteristics of prediction models based on N-terminal pro-B-type natriuretic peptide and clinical risk factors. Finally, the protein predictors performed particularly well close to the time of an HF event, an outcome that was replicated in the Cardiovascular Health Study.

CONCLUSION

A small number of circulating proteins accurately predicted future HF in the AGES-RS cohort of older adults, and they alone encompass the risk information found in a collection of clinical data. Incident HF events were predicted up to 8 years, with predictor performance significantly improving for events occurring less than 1 year ahead, a finding replicated in an external cohort study.

Excess Mortality for Abdominal Aortic Aneurysms and the Potential of Strict Implementation of Cardiovascular Risk Management: A Multifaceted Study Integrating Meta-Analysis, National Registry, and PHAST and TEDY Trial Data

OBJECTIVE

Previous studies imply a profound residual mortality risk following successful abdominal aorta aneurysm (AAA) repair. This excess mortality is generally attributed to increased cardiovascular risk. The aim of this study was (1) to quantify the excess residual mortality for patients with AAA, (2) to evaluate the cross sectional level of cardiovascular risk management, and (3) to estimate the potential of optimised cardiovascular risk management to reduce the excess mortality in these patients.

METHODS

Excess mortality was estimated through a systematic review and meta-analysis, and through data from the Swedish National Health Registry. Cardiovascular risk profiles were individually assessed during eligibility screening of patients with AAA for two multicentre pharmaceutical AAA stabilisation trials. The potential of full implementation of cardiovascular risk management was estimated through the validated Second Manifestations of ARTerial disease (SMART) risk scores algorithm.

RESULTS

The meta-analysis showed a similarly impaired survival for patients who received early repair (small AAA) or regular repair (≥ 55 mm), and a further impaired survival for patients under surveillance for a small AAA. Excess mortality was further quantified using Swedish population data. The data revealed a more than quadrupled and doubled five year mortality rate for women and men who had their AAA repaired, respectively. Evaluation of the level of risk management of 358 patients under surveillance in 16 Dutch hospitals showed that the majority of patients with AAA did not meet therapeutic targets set for risk management in high risk populations, and indicated a more pronounced prevention gap in women. Application of the SMART risk score algorithm predicted that optimal implementation of risk management guidelines would reduce the 10 year risk of major adverse cardiovascular events from 43% to 14%.

CONCLUSION

Independent of the rupture risk, AAA is associated with a worryingly compromised life expectancy with a particularly poor prognosis for women. Optimal implementation of cardiovascular risk prevention guidelines is predicted to profoundly reduce cardiovascular risk.

Normal and abnormal development of the aortic valve and ascending aortic wall: a comprehensive overview of the embryology and pathology of the bicuspid aortic valve

A bicuspid aortic valve (BAV) is the most prevalent congenital cardiac anomaly, in which the valve has only two leaflets, instead of the normal three. Patients with a BAV have an increased risk of aneurysm formation and the development of an aortic dissection. Vascular smooth muscle cells in both the non- and dilated aortic wall are characterized by a maturation defect in all BAV patients, as compared to patients with a tricuspid aortic valve, which can contribute to inherent developmental susceptibility. Besides structural abnormalities of the vascular wall, a turbulent blood flow, caused by bicuspid valve geometry, could expedite the pathological process in the aortic wall, leading to aortopathy. Although the risk for aortopathy is significant, not all BAV patients experience (acute) aortic complications in their lifespan, highlighting the complexity of the pathogenetic process. Recent studies have focused on the embryonic development of semilunar valves and the ascending aortic wall. Their findings highlight that a defect in the embryogenesis could not only explain the development of a malformed aortic valve but also the increased risk for ascending aorta and arch pathology. This review presents an overview of the normal and abnormal development of the aortic valve and the aortic wall: a common defect in early embryogenesis causes the development of a BAV and associated aortopathy.

Coding and regulatory variants are associated with serum protein levels and disease

Circulating proteins can be used to diagnose and predict disease-related outcomes. A deep serum proteome survey recently revealed close associations between serum protein networks and common disease. In the current study, 54,469 low-frequency and common exome-array variants were compared to 4782 protein measurements in the serum of 5343 individuals from the AGES Reykjavik cohort. This analysis identifies a large number of serum proteins with genetic signatures overlapping those of many diseases. More specifically, using a study-wide significance threshold, we find that 2021 independent exome array variants are associated with serum levels of 1942 proteins. These variants reside in genetic loci shared by hundreds of complex disease traits, highlighting serum proteins' emerging role as biomarkers and potential causative agents of a wide range of diseases.

A histopathological classification scheme for abdominal aortic aneurysm disease

OBJECTIVE

Two consensus histopathological classifications for thoracic aortic aneurysms (TAAs) and inflammatory aortic diseases have been issued to facilitate clinical decision-making and inter-study comparison. However, these consensus classifications do not specifically encompass abdominal aortic aneurysms (AAAs). Given its high prevalence and the existing profound pathophysiologic knowledge gaps, extension of the consensus classification scheme to AAAs would be highly instrumental. The aim of this study was to test the applicability of, and if necessary to adapt, the issued consensus classification schemes for AAAs.

METHODS

Seventy-two AAA anterolateral wall samples were collected during elective and emergency open aneurysm repair performed between 2002 and 2013. Histologic analysis (hematoxylin and eosin and Movat Pentachrome) and (semi-quantitative and qualitative) grading were performed in order to map the histological aspects of AAA. Immunohistochemistry was performed for visualization of aspects of the adaptive and innate immune system, and for a more detailed analysis of atherosclerotic lesions in AAA.

RESULTS

Because the existing consensus classification schemes do not adequately capture the aspects of AAA disease, an AAA-specific 11-point histopathological consensus classification was devised. Systematic application of this classification indicated several universal features for AAA (eg, [almost] complete elastolysis), but considerable variation for other aspects (eg, inflammation and atherosclerotic lesions).

CONCLUSIONS

This first multiparameter histopathological AAA consensus classification illustrates the sharp histological contrasts between thoracic and abdominal aneurysms. The value of the proposed scoring system for AAA disease is illustrated by its discriminatory capacity to identify samples from patients with a nonclassical (genetic) variant of AAA disease.

Efficacy of Telmisartan to Slow Growth of Small Abdominal Aortic Aneurysms: A Randomized Clinical Trial

Importance

Currently there is no drug therapy for abdominal aortic aneurysm (AAA).

Objective

To test the efficacy of the angiotensin receptor blocker telmisartan in slowing AAA growth in the Telmisartan in the Management of Abdominal Aortic Aneurysm (TEDY) trial.

Design, Setting, and Participants

A randomized, double-blind, placebo-controlled trial recruited participants between September 6, 2011, and October 5, 2016, to evaluate the efficacy of telmisartan treatment in patients with AAA. Participants with 35- to 49-mm AAAs recruited from Australia, the Netherlands, and the US were randomized 1:1 to receive telmisartan, 40 mg, or identical placebo. Analyses were conducted according to intention-to-treat principles. Final follow-up was conducted on October 11, 2018, and data analysis was performed between June and November 2019.

Intervention

Telmisartan, 40 mg, or identical placebo.

Main Outcomes and Measures

The primary outcome of the difference in AAA growth, assessed on core imaging laboratory-read ultrasonographic scanning, was tested with linear mixed-effects models. Other outcomes included effects on blood pressure, computed tomographic (CT)-measured AAA diameter and volume, time to AAA-related events (AAA repair or mortality due to AAA rupture), and health-related quality of life.

Results

Of 300 intended participants, 210 were enrolled and randomized to receive telmisartan (n = 107) or placebo (n = 103). Of patients included in the intention-to-treat analysis (telmisartan: n = 106, placebo: n = 101), 183 were men (88%); mean (SD) age was 73.5 (7.9) years. At 1 year, participants receiving telmisartan had mean lower systolic (8.9; 95% CI, 4.1-13.8 mm Hg; P < .001) and diastolic (7.0; 4.3-9.8 mm Hg; P < .001) blood pressure levels compared with participants receiving placebo. A total of 188 participants (91%) received at least 2 ultrasonographic scans and 133 participants (64%) had at least 2 CT scans. There was no significant difference in ultrasonographic-assessed AAA growth rates among those assigned telmisartan (1.68 mm/y) or placebo (1.78 mm/y): mean difference, -0.11 mm/y (95% CI, -0.60 to 0.38 mm/y; P = .66). Telmisartan had no significant effects on AAA growth assessed by CT-measured AAA diameter (mean difference, -0.01 mm/y; 95% CI, -0.02 to 0.01 mm/y; P = .23) or volume (mean difference, -0.02 cm3/y; 95% CI, -0.04 to 0.00 cm3/y; P = .11), AAA-related events (relative risk, 1.35; 95% CI, 0.54-3.35; P = .52), or health-related quality of life (mean difference in physical component score at 24 months, 0.4; 95% CI, 0.4-0.4; P = .80). Hypotensive symptoms (eg, syncope) were twice as common among participants receiving telmisartan compared with placebo (28 [26%] vs 13 [13%]; P = .02), but overall adverse event rates were otherwise similar for both groups.

Conclusions and Relevance

This underpowered study did not show a treatment effect for telmisartan on small AAA growth. Future trials will need to ensure adequate sample size and duration of follow-up.

Trial Registrations

anzctr.org.au Identifier: ACTRN12611000931976; ClinicalTrials.gov Identifier: NCT01683084.

Results of an explorative clinical evaluation suggest immediate and persistent post-reperfusion metabolic paralysis drives kidney ischemia reperfusion injury

Delayed graft function is the manifestation of ischemia reperfusion injury in the context of kidney transplantation. While hundreds of interventions successfully reduce ischemia reperfusion injury in experimental models, all clinical interventions have failed. This explorative clinical evaluation examined possible metabolic origins of clinical ischemia reperfusion injury combining data from 18 pre- and post-reperfusion tissue biopsies with 36 sequential arteriovenous blood samplings over the graft in three study groups. These groups included living and deceased donor grafts with and without delayed graft function. Group allocation was based on clinical outcome. Magic angle NMR was used for tissue analysis and mass spectrometry-based platforms were used for plasma analysis. All kidneys were functional at one-year. Integration of metabolomic data identified a discriminatory profile to recognize future delayed graft function. This profile was characterized by post-reperfusion ATP/GTP catabolism (significantly impaired phosphocreatine recovery and significant persistent (hypo)xanthine production) and significant ongoing tissue damage. Failing high-energy phosphate recovery occurred despite activated glycolysis, fatty-acid oxidation, glutaminolysis and autophagia, and related to a defect at the level of the oxoglutarate dehydrogenase complex in the Krebs cycle. Clinical delayed graft function due to ischemia reperfusion injury associated with a post-reperfusion metabolic collapse. Thus, efforts to quench delayed graft function due to ischemia reperfusion injury should focus on conserving metabolic competence, either by preserving the integrity of the Krebs cycle and/or by recruiting metabolic salvage pathways.

PCSK6 Is a Key Protease in the Control of Smooth Muscle Cell Function in Vascular Remodeling

RATIONALE

PCSKs (Proprotein convertase subtilisins/kexins) are a protease family with unknown functions in vasculature. Previously, we demonstrated PCSK6 upregulation in human atherosclerotic plaques associated with smooth muscle cells (SMCs), inflammation, extracellular matrix remodeling, and mitogens.

OBJECTIVE

Here, we applied a systems biology approach to gain deeper insights into the PCSK6 role in normal and diseased vessel wall.

METHODS AND RESULTS

Genetic analyses revealed association of intronic PCSK6 variant rs1531817 with maximum internal carotid intima-media thickness progression in high-cardiovascular risk subjects. This variant was linked with PCSK6 mRNA expression in healthy aortas and plaques but also with overall plaque SMA+ cell content and pericyte fraction. Increased PCSK6 expression was found in several independent human cohorts comparing atherosclerotic lesions versus healthy arteries, using transcriptomic and proteomic datasets. By immunohistochemistry, PCSK6 was localized to fibrous cap SMA+ cells and neovessels in plaques. In human, rat, and mouse intimal hyperplasia, PCSK6 was expressed by proliferating SMA+ cells and upregulated after 5 days in rat carotid balloon injury model, with positive correlation to PDGFB (platelet-derived growth factor subunit B) and MMP (matrix metalloprotease) 2/MMP14. Here, PCSK6 was shown to colocalize and cointeract with MMP2/MMP14 by in situ proximity ligation assay. Microarrays of carotid arteries from Pcsk6^-/- versus control mice revealed suppression of contractile SMC markers, extracellular matrix remodeling enzymes, and cytokines/receptors. Pcsk6^-/- mice showed reduced intimal hyperplasia response upon carotid ligation in vivo, accompanied by decreased MMP14 activation and impaired SMC outgrowth from aortic rings ex vivo. PCSK6 silencing in human SMCs in vitro leads to downregulation of contractile markers and increase in MMP2 expression. Conversely, PCSK6 overexpression increased PDGFBB (platelet-derived growth factor BB)-induced cell proliferation and particularly migration.

CONCLUSIONS

PCSK6 is a novel protease that induces SMC migration in response to PDGFB, mechanistically via modulation of contractile markers and MMP14 activation. This study establishes PCSK6 as a key regulator of SMC function in vascular remodeling. Visual Overview: An online visual overview is available for this article.

Pharmacologic Management of Aneurysms

Current management of aortic aneurysms relies exclusively on prophylactic operative repair of larger aneurysms. Great potential exists for successful medical therapy that halts or reduces aneurysm progression and hence alleviates or postpones the need for surgical repair. Preclinical studies in the context of abdominal aortic aneurysm identified hundreds of candidate strategies for stabilization, and data from preoperative clinical intervention studies show that interventions in the pathways of the activated inflammatory and proteolytic cascades in enlarging abdominal aortic aneurysm are feasible. Similarly, the concept of pharmaceutical aorta stabilization in Marfan syndrome is supported by a wealth of promising studies in the murine models of Marfan syndrome-related aortapathy. Although some clinical studies report successful medical stabilization of growing aortic aneurysms and aortic root stabilization in Marfan syndrome, these claims are not consistently confirmed in larger and controlled studies. Consequently, no medical therapy can be recommended for the stabilization of aortic aneurysms. The discrepancy between preclinical successes and clinical trial failures implies shortcomings in the available models of aneurysm disease and perhaps incomplete understanding of the pathological processes involved in later stages of aortic aneurysm progression. Preclinical models more reflective of human pathophysiology, identification of biomarkers to predict severity of disease progression, and improved design of clinical trials may more rapidly advance the opportunities in this important field.

Inflammation induces endothelial-to-mesenchymal transition and promotes vascular calcification through downregulation of BMPR2

Endothelial‐to‐mesenchymal transition (EndMT) has been unveiled as a common cause for a multitude of human pathologies, including cancer and cardiovascular disease. Vascular calcification is a risk factor for ischemic vascular disorders and slowing calcification may reduce mortality in affected patients. The absence of early biomarkers hampers the identification of patients at risk. EndMT and vascular calcification are induced upon cooperation between distinct stimuli, including inflammatory cytokines and transforming growth factor beta (TGF‐β) family members. However, how these signaling pathways interplay to promote cell differentiation and eventually vascular calcification is not well understood. Using in vitro and ex vivo analysis in animal models and patient‐derived tissues, we have identified that the pro‐inflammatory cytokines tumor necrosis factor alpha (TNF‐α) and interleukin‐1 beta (IL‐1β) induce EndMT in human primary aortic endothelial cells, thereby sensitizing them for BMP‐9‐induced osteogenic differentiation. Downregulation of the BMP type II receptor BMPR2 is a key event in this process. Rather than compromising BMP canonical signal transduction, loss of BMPR2 results in decreased JNK signaling in ECs, thus enhancing BMP‐9‐induced mineralization. Altogether, our results point at the BMPR2–JNK signaling axis as a key pathway regulating inflammation‐induced EndMT and contributing to calcification. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Qualitative evaluation of coronary atherosclerosis in a large cohort of young and middle-aged Dutch tissue donors implies that coronary thrombo-embolic manifestations are stochastic

Background and aims

With the intention to gain support for the hypothesis that incident ischemic complications of atherosclerotic disease involve a stochastic aspect, we performed a histological, qualitative evaluation of the epidemiology of coronary atherosclerotic disease in a cohort of aortic valve donors.

Patients and methods

Donors (n = 695, median age 54, range 11–65 years) were dichotomized into a non-cardiovascular (non-CVD) and a cardiovascular disease death (CVD) group. Consecutive 5 mm proximal left coronary artery segments were Movat stained, and the atherosclerotic burden for each segment was graded (revised AHA-classification).

Results

Non-CVD and CVD groups showed steep increase of atherosclerosis severity beyond the age of 40, resulting in an endemic presence of advanced atherosclerosis in men over 40 and women over 50 years. In fact, only 19% of the non-CVD and 6% of the CVD donors over 40 years were classified with a normal LCA or a so called non-progressive lesion type. Fibrous calcified plaques (FCP), the consolidated remnants of earlier ruptured lesions, dominated in both non-CVD and CVD donors. Estimates of the atherosclerosis burden (i.e. average lesion grade, proportion of FCPs, and average number of FCPs per cross-section) were all higher in the CVD group (p<1.10⁻¹⁶, p<0.0001, and p<0.05, respectively).

Conclusions

Dominance of consolidated FCP lesions in males over 40 and females over 50 years, show that plaque ruptures in the left coronary artery are common. However, the majority of these ruptures remain asymptomatic. This implies that the atherosclerotic process is repetitive. A relative difference in disease burden between CVD and non-CVD donors supports the concept that complications of atherosclerotic disease involve a stochastic element.

Abstract 244: A Qualitative Evaluation of Coronary Atherosclerosis in Young and Middle-aged Dutch Tissue Donors

Background: Ischemic coronary events relate to qualitative changes in plaque characteristics. Epidemiological data on qualitative aspects of the coronary atherosclerotic process (e.g. plaque progression and destabilization) is missing.

Objective: to qualitatively map the epidemiology of atherosclerosis burden in a representative cohort of deceased individuals

Methods: this is a systematic, qualitative analysis of atherosclerotic burden in the proximal left coronary artery (LCA) segment of 695 tissue donors (median age 54, range 11-65 years). Based on the cause of death, donors were dichotomized into a non-cardiovascular (non-CVD group) and a cardiovascular disease (CVD) group. Consecutive, 5 mm LCA segments were Movat stained, and the atherosclerotic burden for each segment qualitatively graded (revised AHA-classification).

Results: non-CVD and CVD groups show rapid acceleration of atherosclerosis severity after the age of 40; resulting in an almost endemic presence of advanced atherosclerosis in men and women over 40 respectively 50 years. In fact, only 19% of the non-CVD and 6% of the CVD donors over 40 presented with a normal LCA or non-progressive lesion type. The consolidated fibrous calcified plaque (FCP) dominated in both non-CVD and CVD donors over 40. Estimates of atherosclerosis load (i.e. average lesion grade, proportion of FCPs, and average number of FCPs per cross-section were all higher in the CVD group (P<1.10 -16 , P<0.0001 and P<0.05 respectively)

Conclusions: advanced atherosclerotic disease is endemic in individuals over 40. Dominance of FCP lesions and the higher disease load in CVD donors imply that the atherosclerotic process is repetitive. Abundance of FCPs suggest that complications of plaque rupture are stochastic. This study was in part funded by the European Commission (Cartardis, FP7 HEALTH.2013.2.4.2-1).

Abstract 627: Combined Plaque Evaluation by Ultrasound and Microarrays Reveals Bclaf1 as a Novel Regulator of Smooth Muscle Cell Transdifferentiation in Atherosclerosis

Objective: Understanding molecular processes behind carotid plaque instability is necessary to develop methods that can identify patients and lesions at risk of stroke. Here, we investigated molecular signatures in human plaques stratified by echogenicity as assessed by duplex ultrasound (US).

Results: Plaque echogenicity measured by US was correlated to microarray profiles from lesions retrieved at surgery (n=96). Pathway analyses highlighted enrichment of cell apoptosis and proliferation, and BCLAF1 (BCL2 associated factor 1) as the most significantly dysregulated gene (adjusted p<0.0001). BCLAF1 was strongly downregulated in plaques vs. control tissues, positively correlated to markers of cell proliferation and negatively to apoptosis, at both transcriptomic and proteomic level. Immunohistochemistry showed that BCLAF1 was localized in smooth muscle cells (SMCs) nuclei and repressed early during atherogenesis, but reappeared in CD68+ cells in advanced plaques. Proximity ligation assay demonstrated interaction of BCLAF1 with previously reported interaction partners THRAP3 and BCL2, in normal arteries and plaques. In vitro , stimulation of SMCs with pro-survival factors EGF, bFGF, PDGFB resulted in induction of BCLAF1, while it was suppressed by macrophage-conditioned medium. Moreover, BCLAF1 silencing in SMCs led to downregulation of BCL2 and SMC markers, and a decrease in proliferation and adhesion (p<0.0001). Transdifferentiation of SMCs using oxLDL, confirmed by CD68 upregulation and MYH11 repression, was accompanied by upregulation of BCLAF1. However, a combination of oxLDL exposure and BCLAF1 silencing, resulted in preserved expression of MYH11 and prevented transdifferentiation. Finally, BCLAF1 expression in CD68+/BCL2+ cells of SMC origin, was verified in plaques from MYH11-lineage tracing atherosclerotic mice.

Conclusions: Carotid plaque echogenicity correlated with enrichment of molecular pathways associated with cell survival and apoptosis and identified BCLAF1, previously not described in atherosclerosis, as the most dysregulated gene. Functionally, BCLAF1 appeared to promote SMC survival by transdifferentiation into macrophage-like phenotype, by interacting with BCL2 and THRAP3.

Leukocyte Dynamics during the Evolution of Human Coronary Atherosclerosis: Conclusions from a Sevenfold, Chromogen-Based, Immunohistochemical Evaluation

Atherosclerosis is a complex process with strong inflammatory component. We developed a straightforward sevenfold staining protocol for simultaneous assessment of dominant leukocyte classes, vascularization, and expression of the putative foam cell maker CD36. The method was applied on human coronaries covering the full spectrum of atherosclerotic disease. Results confirm the progressive association of macrophages and T cells with the process and a global presence of mast cells. B cells are exclusively present in adventitial follicles that accompany the process plaque destabilization (thin cap and ruptured lesions) and are otherwise absent. Neutrophils are only present as part of the hemorrhage that accompanies plaque rupture. This study does not classify CD36 as a key factor in foam cell formation. Observed macrophage accumulation in the neointima of stabilized fibrous calcified plaques is consistent with a process of neoatherosclerosis. This study on human coronaries shows a progressive association of macrophage and T-cell abundance with plaque progression. Follicle-like structures are transiently present during the process of plaque destabilization. Plaque healing is accompanied by cessation of the inflammatory response but followed by a new cycle of atherosclerosis.

No indications for platelet activation in acute clinical myocardial or renal ischemia/reperfusion injury

The pathophysiology of ischemia/reperfusion (I/R) injury is complex and poorly understood. Animal studies imply platelet activation as an initiator of the inflammatory response upon reperfusion. However, it remains unclear whether and how these results translate to clinical I/R. This study evaluates putative platelet activation in the context of two forms of clinical I/R (heart valve surgery with aortic-cross clamping, n = 39 and kidney transplantation, n = 34). The technique of sequential selective arteriovenous (AV) measurements over the reperfused organs was applied to exclude the influence of systemic changes occurring during surgery while simultaneously maximizing sensitivity. Platelet activation and degranulation was evaluated by assessing the expression levels of established markers, i.e. RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted), β-thromboglobulin (β-TG), platelet-derived growth factor (PDGF)-BB and CXCL8 (known as interleukin-8), and by employing an in-vitro assay that specifically tests for platelet excitability. Moreover, a histological analysis was performed by means of CD41 staining. Results show stable RANTES, β-TG, PDGF-BB and CXCL8 AV-concentrations within the first half hour over the reperfused organs, suggesting that myocardial and renal I/R are not associated with platelet activation. Results from the platelet excitability assay were in line with these findings and indicated reduced and stable platelet excitability following renal and myocardial reperfusion, respectively. Histological analysis yield evidence of platelet marginalization in the reperfused organs. In conclusion, results from this study do not support a role for platelet activation in early phases of clinical I/R injury.

The Consequences of Real Life Practice of Early Abdominal Aortic Aneurysm Repair: A Cost-Benefit Analysis

BACKGROUND

The reported 54 mm median intervention diameter for endovascular aneurysm repair (EVAR) in the Vascular Quality Initiative and European data from the Pharmaceutical Aneurysm Stabilisation Trial (PHAST) implies that in real life the majority of abdominal aortic aneurysm (AAA) repairs occur at diameters smaller than the consensus intervention threshold of 55 mm. This study explores the potential consequences of this practice.

METHODS

The differences between real life AAA repair and consensus based intervention threshold were explored in reported data from vascular quality initiatives and PHAST. The subsequent consequences of advancement of endovascular aneurysm repair (EVAR) were estimated using a multistate model based on life tables for the EVAR Medicare population.

RESULTS

There appears an approximate 5 mm difference in AAA diameter between real life practice and consensus intervention threshold. Assuming a 2.5 mm annual growth rate, this results in an approximately 2 year advancement of AAA repair. According to the model used, early repair reduces overall small aneurysm patient mortality by 2.3%, it results in 21.9% more EVAR procedures, more EVAR related deaths, and 42.3% and 36.8% more open and endovascular re-interventions, respectively. Cost-benefit estimates imply 482 fewer AAA related deaths, but 140 extra EVAR related deaths for a population of more than 30,000 AAA patients, and a 300 million USD increase in health costs for the 8 year observation period in the Medicare population.

CONCLUSIONS

In the real life situation a large proportion of EVAR procedures appear to occur before reaching the consensus threshold. Although this reduces mortality, it comes at a cost of approximately 1 million USD per prevented rupture related death.

Myostatin mediates abdominal aortic atherosclerosis progression by inducing vascular smooth muscle cell dysfunction and monocyte recruitment

Myostatin (Mstn) is a skeletal muscle growth inhibitor involved in metabolic disorders and heart fibrosis. In this study we sought to verify whether Mstn is also operative in atherosclerosis of abdominal aorta. In human specimens, Mstn expression was almost absent in normal vessels, became detectable in the media of non-progressive lesions and increased with the severity of the damage. In progressive atherosclerotic lesions, Mstn was present in the media, neointima, plaque shoulder and in infiltrating macrophages. Mstn co-localized with α-smooth muscle actin (α-SMA) staining and with some CD45+ cells, indicating Mstn expression in VSMCs and bloodstream-derived leukocytes. In vitro, Mstn was tested in VSMCs and monocytes. In A7r5 VSMCs, Mstn downregulated proliferation and Smoothelin mRNA, induced cytoskeletal rearrangement, increased migratory rate and MCP-1/CCR2 expression. In monocytes (THP-1 cells and human monocytes), Mstn acted as a chemoattractant and increased the MCP-1-dependent chemotaxis, F-actin, α-SMA, MCP-1 and CCR2 expression; in turn, MCP-1 increased Mstn mRNA. Mstn induced JNK phosphorylation both in VSMCs and monocytes. Our results indicate that Mstn is overexpressed in abdominal aortic wall deterioration, affects VSMCs and monocyte biology and sustains a chronic inflammatory milieu. These findings propose to consider Mstn as a new playmaker in atherosclerosis progression.

Histological evaluation disqualifies IMT and calcification scores as surrogates for grading coronary and aortic atherosclerosis

BACKGROUND/OBJECTIVES

Carotid intimal media thickness (IMT) and coronary calcium scores (CCS) are thought to reflect atherosclerotic burden. The validity of this assumption for IMT is challenged by recent meta-analyses; for CCS by absence of a relationship between negative scores, and freedom of future events. As such, we considered evaluation of the relationship between tissue IMT and CCS, and extend of atherosclerotic disease relevant.

METHODS

Analyses were performed on donor aortas obtained during renal graft procurement, and on coronary arteries collected during heart valve procurement for tissue donation. Movat pentachrome and Hematoxylin staining was performed, and the degree of atherosclerosis histologically graded. IMT and presence of calcium deposits were quantified on graded tissue sections.

RESULTS

304 aortas and 185 coronary arteries covering the full atherosclerotic spectrum were evaluated. Aortas and coronaries showed similar relationships between tissue IMT and degree of atherosclerosis, with gradual increase in tissue IMT during earlier phases of atherosclerosis (r=0.68 and r=0.30, P<0.00001 for aorta and coronaries respectively), followed by plateauing of the curve in intermediate and advanced stages. Results for tissue IMT reveal high variability, resulting in wide confidence intervals. Results for CCS are similar for aorta and coronaries, with calcium depositions limited to advanced lesions.

CONCLUSIONS

Histological IMT measurements for the aorta and coronaries show large variations around the trend and plateauing of, and possibly reductions in IMT in late stage atherosclerotic disease. These observations for the aorta and coronaries may (partly) explain the limited benefit of including carotid IMT in risk prediction algorithms.

Succinate Accumulation and Ischemia-Reperfusion Injury: Of Mice but Not Men, a Study in Renal Ischemia-Reperfusion

A recent seminal paper implicated ischemia-related succinate accumulation followed by succinate-driven reactive oxygen species formation as a key driver of ischemia-reperfusion injury. Although the data show that the mechanism is universal for all organs tested (kidney, liver, heart, and brain), a remaining question is to what extent these observations in mice translate to humans. We showed in this study that succinate accumulation is not a universal event during ischemia and does not occur during renal graft procurement; in fact, tissue succinate content progressively decreased with increasing graft ischemia time (p < 0.007). Contrasting responses were also found with respect to mitochondrial susceptibility toward ischemia and reperfusion, with rodent mitochondria robustly resistant toward warm ischemia but human and pig mitochondria highly susceptible to warm ischemia (p < 0.05). These observations suggest that succinate-driven reactive oxygen formation does not occur in the context of kidney transplantation. Moreover, absent allantoin release from the reperfused grafts suggests minimal oxidative stress during clinical reperfusion.

The composition of collagen in the aneurysm wall of men and women

BACKGROUND

Loss of vessel wall integrity by degradation is essential for the development of abdominal aortic aneurysm (AAA) and ultimately its rupture. The observed greater rupture rate in women with AAA might be related to gender differences in the biomechanical properties of the aneurysm wall. The aim of the study was to compare the biomechanically important structure of collagen between men and women with AAA.

METHODS

Biopsies of the aneurysm walls were obtained during elective open repair of men (n = 14) and women (n = 14) treated for AAA. High-performance liquid chromatography (HPLC), Western blot, messenger RNA expression, and histochemical analyses were performed to assess the cross-linking and the amount and the composition of collagen.

RESULTS

There was neither a difference in the thickness of the aneurysm wall, nor in the histological evaluation of the collagen composition between the sexes. Relative collagen content in the aneurysm wall was similar in men and women, as assessed by messenger RNA expression and HPLC. Collagen cross-linking differed between the sexes; women had more lysyl pyridinoline (LP) than men (0.140 vs 0.07; P = .005), resulting in a lower hydroxyl pyridinoline (HP):LP ratio (3.28 vs 8.41; P = .003). There was no difference in messenger RNA and protein expressions of lysyl hydroxylase and lysyl oxidase to associate with the lower HP:LP ratio in women.

CONCLUSIONS

The composition of collagen in the aneurysm wall of men and women are in several aspects similar, with the exception of collagen cross-linking, suggesting that the difference in rupture rate between the sexes rather depend on the composition of other vessel wall structures.

Effects of doxycycline on local and systemic inflammation in stable COPD patients, a randomized clinical trial

Neutrophilic inflammation plays a causal role in Chronic Obstructive Pulmonary Disease (COPD). Neutrophil derived myeloperoxidase(MPO) matrix metalloproteinases(MMP's), and elastases are thought to contribute to the perpetuation of the disease. The tetracycline analogue doxycycline has been shown to inhibit neutrophil-mediated inflammation. It was thus reasoned that doxycycline may attenuate neutrophil-mediated inflammation in COPD.

METHODS

In this double blind randomized controlled trial the effect of a 3-week course of doxycycline on sputum and systemic inflammatory parameters was evaluated in stable COPD patients. In order to exclude inflammation by bacterial colonisation patients must have 2 negative sputum cultures in the previous year. The effect of doxycycline treatment on inflammatory markers (TNF-α, IL-1β and IL-6) and neutrophil specific markers in sputum (MPO, MMP's, and IL-8) and serum C-reactive protein was evaluated. Sputum was obtained by sputum induction with hypertonic saline.

RESULTS

A total of 41 patients were included. Ten patients were excluded as they were not able to produce sputum at the first or second visit. Baseline characteristics were similar in the two groups. In the remaining patients doxycycline did not influence sputum MPO concentrations. Also MMP-8 and 9, IL-6 and IL-8 concentrations as well as lung function parameters were not affected by doxycycline. Systemic inflammation by means of CRP was also not influenced by doxycycline.

CONCLUSION

A three week course of doxycycline did not influence MPO sputum levels nor any of the other inflammatory sputum and systemic markers.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00857038 URL: clinicaltrials.gov.

TElmisartan in the management of abDominal aortic aneurYsm (TEDY): The study protocol for a randomized controlled trial

BACKGROUND

Experimental studies suggest that angiotensin II plays a central role in the pathogenesis of abdominal aortic aneurysm. This trial aims to evaluate the efficacy of the angiotensin receptor blocker telmisartan in limiting the progression of abdominal aortic aneurysm.

METHODS/DESIGN

Telmisartan in the management of abdominal aortic aneurysm (TEDY) is a multicentre, parallel-design, randomised, double-blind, placebo-controlled trial with an intention-to-treat analysis. We aim to randomly assign 300 participants with small abdominal aortic aneurysm to either 40 mg of telmisartan or identical placebo and follow patients over 2 years. The primary endpoint will be abdominal aortic aneurysm growth as measured by 1) maximum infra-renal aortic volume on computed tomographic angiography, 2) maximum orthogonal diameter on computed tomographic angiography, and 3) maximum diameter on ultrasound. Secondary endpoints include change in resting brachial blood pressure, abdominal aortic aneurysm biomarker profile and health-related quality of life. TEDY is an international collaboration conducted from major vascular centres in Australia, the United States and the Netherlands.

DISCUSSION

Currently, no medication has been convincingly demonstrated to limit abdominal aortic aneurysm progression. TEDY will examine the potential of a promising treatment strategy for patients with small abdominal aortic aneurysms.

TRIAL REGISTRATION

Australian and Leiden study centres: Australian New Zealand Clinical Trials Registry ACTRN12611000931976 , registered on 30 August 2011; Stanford study centre: clinicaltrials.gov NCT01683084 , registered on 5 September 2012.

Abstract 136: Identification of Melanoregulin as Novel Marker for Atherosclerosis

Introduction: Novel biomarkers identification in atherosclerosis is needed for early detection/intervention of vascular diseases. Impaired lysosomal function and autophagy cause abnormal lipid accumulation in foam cells and contribute to atherosclerosis progression. By microarray of human carotid plaques in the Biobank of Karolinska Endarterectomies (BiKE), we found that melanoregulin (MREG), a protein associated with lysosomes, phagocytosis and autophagy and previously not associated with atherosclerosis, was significantly up-regulated in symptomatic (S) versus asymptomatic (AS) patients. MREG expression was also significantly correlated to inflammatory, lipid and endo/lysosome markers.

Hypothesis: We hypothesized that MREG modulates clearance of engulfed lipids and extracellular material in lipid-loaded foam cells.

Methods: MREG mRNA and protein levels were evaluated in human carotid plaque tissue from S and AS patients by qPCR and immunohistochemistry, respectively. MREG, together with lysosome and lipid markers (LAMP2 and PLIN2 respectively) was identified by immunofluorescence in human monocyte cells (THP-1), loaded with modified LDL. To investigate autophagy/MREG correlation, THP-1 cells were incubated with autophagy inhibitor (chloroquine, CQ) and MREG mRNA was assessed by qPCR.

Results: MREG mRNA is elevated in human atherosclerotic lesions versus normal artery (11.21 folds, P<0.0001). In human aortic tissue MREG expression is correlated to the lesion progression and localizes in infiltrating macrophage-derived foam cells. In the human carotid plaque, MREG co-localizes with CD68+ and PLIN2+ cells, lined to the necrotic core. MREG protein was also detected in PMA-differentiated THP-1 cells. In lipid-loaded THP-1, MREG is co-localized with lysosomal LAMP2. Moreover, MREG expression is increased in THP-1 cells by incubation with PMA, starving medium and CQ.

Conclusions: We show here for the first time that MREG is expressed in atherosclerotic lesions and is associated with endo/lysosomes in human macrophages. Furthermore we show that autophagy inhibition increases MREG mRNA expression. Future studies will investigate how MREG expression levels will affect phagocytic activity of lipid-loaded macrophages.

SLUG Is Expressed in Endothelial Cells Lacking Primary Cilia to Promote Cellular Calcification

Objective—

Arterial calcification is considered a major cause of death and disabilities worldwide because the associated vascular remodeling leads to myocardial infarction, stroke, aneurysm, and pulmonary embolism. This process occurs via poorly understood mechanisms involving a variety of cell types, intracellular mediators, and extracellular cues within the vascular wall. An inverse correlation between endothelial primary cilia and vascular calcified areas has been described although the signaling mechanisms involved remain unknown. We aim to investigate the signaling pathways regulated by the primary cilium that modulate the contribution of endothelial cells to vascular calcification.

Approach and Results—

We found that human and murine endothelial cells lacking primary cilia are prone to undergo mineralization in response to bone morphogenetic proteins stimulation in vitro. Using the Tg737 orpk/orpk cillium-defective mouse model, we show that nonciliated aortic endothelial cells acquire the ability to transdifferentiate into mineralizing osteogenic cells, in a bone morphogenetic protein–dependent manner. We identify β-CATENIN–induced SLUG as a key transcription factor controlling this process. Moreover, we show that the endothelial expression of SLUG is restricted to atheroprone areas in the aorta of LDLR −/− mice. Finally, we demonstrate that SLUG and phospho-homolog of the Drosophila protein, mothers against decapentaplegic (MAD) and the Caenorhabditis elegans protein SMA (from gene sma for small body size)-1/5/8 expression increases in endothelial cells constituting the vasa vasorum in the human aorta during the progression toward atherosclerosis.

Conclusions—

We demonstrated that the lack of primary cilia sensitizes the endothelium to undergo bone morphogenetic protein–dependent-osteogenic differentiation. These data emphasize the role of the endothelial cells on the vascular calcification and uncovers SLUG as a key target in atherosclerosis.

Establishment of a general NAFLD scoring system for rodent models and comparison to human liver pathology

Background and aims

The recently developed histological scoring system for non-alcoholic fatty liver disease (NAFLD) by the NASH Clinical Research Network (NASH-CRN) has been widely used in clinical settings, but is increasingly employed in preclinical research as well. However, it has not been systematically analyzed whether the human scoring system can directly be converted to preclinical rodent models. To analyze this, we systematically compared human NAFLD liver pathology, using human liver biopsies, with liver pathology of several NAFLD mouse models. Based upon the features pertaining to mouse NAFLD, we aimed at establishing a modified generic scoring system that is applicable to broad spectrum of rodent models.

Methods

The histopathology of NAFLD was analyzed in several different mouse models of NAFLD to define generic criteria for histological assessment (preclinical scoring system). For validation of this scoring system, 36 slides of mouse livers, covering the whole spectrum of NAFLD, were blindly analyzed by ten observers. Additionally, the livers were blindly scored by one observer during two separate assessments longer than 3 months apart.

Results

The criteria macrovesicular steatosis, microvesicular steatosis, hepatocellular hypertrophy, inflammation and fibrosis were generally applicable to rodent NAFLD. The inter-observer reproducibility (evaluated using the Intraclass Correlation Coefficient) between the ten observers was high for the analysis of macrovesicular steatosis and microvesicular steatosis (ICC = 0.784 and 0.776, all p<0.001, respectively) and moderate for the analysis of hypertrophy and inflammation (ICC = 0.685 and 0.650, all p<0.001, respectively). The intra-observer reproducibility between the different observations of one observer was high for the analysis of macrovesicular steatosis, microvesicular steatosis and hypertrophy (ICC = 0.871, 0.871 and 0.896, all p<0.001, respectively) and very high for the analysis of inflammation (ICC = 0.931, p<0.001).

Conclusions

We established a simple NAFLD scoring system with high reproducibility that is applicable for different rodent models and for all stages of NAFLD etiology.

ACE inhibitors potently reduce vascular inflammation, results of an open proof-of-concept study in the abdominal aortic aneurysm

BACKGROUND

Independent of their blood pressure lowering effect, ACE inhibitors are thought to reduce vascular inflammation. The clinical relevance of this effect is unclear with the current knowledge. Abdominal aortic aneurysms (AAA) are characterized by a broad, non-specific inflammatory response, and thus provide a clinical platform to evaluate the anti-inflammatory potential of ACE inhibitors.

METHODS AND RESULTS

Eleven patients scheduled for open AAA repair received ramipril (5 mg/day) during 2-4 weeks preceding surgery. Aortic wall samples were collected during surgery, and compared to matched samples obtained from a biobank. An anti-inflammatory potential was evaluated in a comprehensive analysis that included immunohistochemistry, mRNA and protein analysis. A putative effect of ACE inhibitors on AAA growth was tested separately by comparing 18-month growth rate of patients on ACE inhibitors (n = 82) and those not taking ACE inhibitors (n = 204). Ramipril reduces mRNA expression of multiple pro-inflammatory cytokines such as IL-1β, IL-6, IL-8, TNF -α, Interferon-[Formula: see text], and MCP-1, as well as aortic wall IL-8 and MCP-1 (P = 0.017 and 0.008, respectively) protein content. The is followed by clear effects on cell activation that included a shift towards anti-inflammatory macrophage (M2) subtype. Evaluation of data from the PHAST cohort did not indicate an effect of ACE inhibitors on 18-month aneurysm progression (mean difference at 18 months: -0.24 mm (95% CI: -0.90-0.45, P = NS).

CONCLUSIONS

ACE inhibition quenches multiple aspects of vascular inflammation in AAA. However, this does not translate into reduced aneurysm growth.

TRIAL REGISTRATION

Nederlands Trial Register 1345.

Metabolically induced liver inflammation leads to NASH and differs from LPS- or IL-1β-induced chronic inflammation

The nature of the chronic inflammatory component that drives the development of non-alcoholic steatohepatitis (NASH) is unclear and possible inflammatory triggers have not been investigated systematically. We examined the effect of non-metabolic triggers (lipopolysaccharide (LPS), interleukin-1β (IL-1β), administered by slow-release minipumps) and metabolic dietary triggers (carbohydrate, cholesterol) of inflammation on the progression of bland liver steatosis (BS) to NASH. Transgenic APOE3*Leiden.huCETP (APOE3L.CETP) mice fed a high-fat diet (HFD) developed BS after 10 weeks. Then, inflammatory triggers were superimposed or not (control) for six more weeks. Mouse livers were analyzed with particular emphasis on hallmarks of inflammation which were defined in human liver biopsies with and without NASH. Livers of HFD-treated control mice remained steatotic and did not progress to NASH. All four inflammatory triggers activated hepatic nuclear factor-κB (NF-κB) significantly and comparably (≥5-fold). However, HFD+LPS or HFD+IL-1β did not induce a NASH-like phenotype and caused intrahepatic accumulation of almost exclusively mononuclear cells. By contrast, mice treated with metabolic triggers developed NASH, characterized by enhanced steatosis, hepatocellular hypertrophy, and formation of mixed-type inflammatory foci containing myeloperoxidase-positive granulocytes (neutrophils) as well as mononuclear cells, essentially as observed in human NASH. Specific for the metabolic inducers was an activation of the proinflammatory transcription factor activator protein-1 (AP-1), neutrophil infiltration, and induction of risk factors associated with human NASH, that is, dyslipidemia (by cholesterol) and insulin resistance (by carbohydrate). In conclusion, HFD feeding followed by NF-κB activation per se (LPS, IL-1β) does not promote the transition from BS to NASH. HFD feeding followed by metabolically evoked inflammation induces additional inflammatory components (neutrophils, AP-1 pathway) and causes NASH.

VEGF-B-induced vascular growth leads to metabolic reprogramming and ischemia resistance in the heart

Angiogenic growth factors have recently been linked to tissue metabolism. We have used genetic gain- and loss-of function models to elucidate the effects and mechanisms of action of vascular endothelial growth factor-B (VEGF-B) in the heart. A cardiomyocyte-specific VEGF-B transgene induced an expanded coronary arterial tree and reprogramming of cardiomyocyte metabolism. This was associated with protection against myocardial infarction and preservation of mitochondrial complex I function upon ischemia-reperfusion. VEGF-B increased VEGF signals via VEGF receptor-2 to activate Erk1/2, which resulted in vascular growth. Akt and mTORC1 pathways were upregulated and AMPK downregulated, readjusting cardiomyocyte metabolic pathways to favor glucose oxidation and macromolecular biosynthesis. However, contrasting with a previous theory, there was no difference in fatty acid uptake by the heart between the VEGF-B transgenic, gene-targeted or wildtype rats. Importantly, we also show that VEGF-B expression is reduced in human heart disease. Our data indicate that VEGF-B could be used to increase the coronary vasculature and to reprogram myocardial metabolism to improve cardiac function in ischemic heart disease.

Subject Categories Cardiovascular System; Metabolism

See also: C Kupatt and R Hinkel (March 2014)

Quantitative profiling of oxylipins through comprehensive LC-MS/MS analysis: application in cardiac surgery

Oxylipins, including eicosanoids, affect a broad range of biological processes, such as the initiation and resolution of inflammation. These compounds, also referred to as lipid mediators, are (non-) enzymatically generated by oxidation of polyunsaturated fatty acids such as arachidonic acid (AA). A plethora of lipid mediators exist which makes the development of generic analytical methods challenging. Here we developed a robust and sensitive targeted analysis platform for oxylipins and applied it in a biological setting, using high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) operated in dynamic multiple reaction monitoring (dMRM). Besides the well-described AA metabolites, oxylipins derived from linoleic acid, dihomo-γ-linolenic acid, α-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid were included. Our comprehensive platform allows the quantitative evaluation of approximately 100 oxylipins down to low nanomolar levels. Applicability of the analytical platform was demonstrated by analyzing plasma samples of patients undergoing cardiac surgery. Altered levels of some of the oxylipins, especially in certain monohydroxy fatty acids such as 12-HETE and 12-HEPE, were observed in samples collected before and 24 h after cardiac surgery. These findings indicate that this generic oxylipin profiling platform can be applied broadly to study these highly bioactive compounds in relation to human disease.

Abstract 63: CXCL8 Signaling Pathways and the Aortic Abdominal Aneurysm: The Oral CXCR2 Antagonist DF2156A Fully Abrogates Aneurysm Formation

An aneurysm of the abdominal aorta (AAA) is part of the atherososclerotic spectrum of diseases. The disease is characterized by a localized dilatation of the infrarenal artery and rupture of the weakened segment is now responsible for more than 15.000 annual deaths in the US alone. The pathology of AAA is complex and poorly understood. It is generally conceived that AAA is characterized by a localized general pro-inflammatory response and an accompanying protease imbalance that is held responsible for the progressive weakening of the aortic wall. The exact inflammatory pathways that drive aneurysm progression and that distinguish AAA from occlusive atherosclerotic disease have not yet been identified. We previously reported a 21-fold increase in CXCL8 mRNA expression and an approx. 300-fold increase in CXCL8 protein levels in human AAA, as compared to human occlusive atherosclerotic disease (p<0.001); suggesting that activation of the CXCL8/CXCR1-2 axis is a distinctive feature of AAA.

We now performed a histological and protein analysis of human AAA and human occlusive atherosoclerotic disease, showing abundant presence of the CXCL8 receptors CXCR1 and 2 as well as increased ERK phosphorylation in AAA. Evaluation on cellular level identified abundant neutrophils (fully absent in atherosoclerosis) as well as increased neovascularization as clear distinctive features of AAA, a finding that is consistent with increased CXCL8 signaling. To test a putative role of CXCL8/CXCR1-2 system in AAA we next tested whether the oral CXCR2 antagonist DF2156A prevents aneurysm formation in the elastase model, a well established model of the disease. This study showed that a once daily dose of 15mg/kg DF2156A fully abrogates aneurysm formation in the elastase model (71.86% aortic diameter growth in 14 days (SEM 4.88) in untreated animals vs. 17.66% growth (SEM 1.71) in animals treated with DF2156A) (p<0.001).

In conclusion, these studies identify activation of the CXCL8/CXCR1-2 pathway as a distinctive feature of AAA and characterize this pathway as a potential target for the stabilization of AAA.

Genome-wide association study identifies six new loci influencing pulse pressure and mean arterial pressure

Numerous genetic loci influence systolic blood pressure (SBP) and diastolic blood pressure (DBP) in Europeans ^1-3. We now report genome-wide association studies of pulse pressure (PP) and mean arterial pressure (MAP). In discovery (N=74,064) and follow-up studies (N=48,607), we identified at genome-wide significance (P= 2.7×10^-8 to P=2.3×10^-13) four novel PP loci (at 4q12 near CHIC2/PDGFRAI, 7q22.3 near PIK3CG, 8q24.12 in NOV, 11q24.3 near ADAMTS-8), two novel MAP loci (3p21.31 in MAP4, 10q25.3 near ADRB1) and one locus associated with both traits (2q24.3 near FIGN) which has recently been associated with SBP in east Asians. For three of the novel PP signals, the estimated effect for SBP was opposite to that for DBP, in contrast to the majority of common SBP- and DBP-associated variants which show concordant effects on both traits. These findings indicate novel genetic mechanisms underlying blood pressure variation, including pathways that may differentially influence SBP and DBP.

The outer wall of small airways is a major site of remodeling in fatal asthma

BACKGROUND

Structural and inflammatory changes in asthma involve both the large and small airways, with involvement of the distal lung being related to disease severity. We have previously shown that changes in the extracellular matrix (ECM) composition of the distal lung are associated with loss of alveolar attachments in patients with fatal asthma. However, major ECM elements, such as collagen I and fibronectin and their regulators, have not been addressed at the distal level.

OBJECTIVE

We sought to evaluate ECM remodeling in the distal lungs of asthmatic patients.

METHODS

Using immunohistochemistry and image analysis, we determined the content of collagen I and III, fibronectin, and matrix metalloproteinases (MMPs) 1, 2, and 9 and tissue inhibitors of metalloproteinase (TIMPs) 1 and 2 in the large and small airways and lung parenchyma of 24 patients with fatal asthma and compared the results with those of 11 nonasthmatic control subjects. Protein content was defined as the area of positive staining divided by basement membrane or septum length.

RESULTS

We observed increased collagen I and decreased collagen III content in the small airways of asthmatic patients compared with that seen in control subjects. Greater fibronectin and MMP-1, MMP-2, and MMP-9 content was observed at the outer area of the small airways in asthmatic patients. MMP content was also increased in the peribronchiolar parenchyma in asthmatic patients. In contrast, TIMP expression was only increased in the large airways of asthmatic patients compared with that seen in control subjects.

CONCLUSIONS

The outer area of the small airways is a major site of ECM remodeling in fatal asthma, potentially contributing to functional changes and the loss of airway-parenchyma interdependence observed in patients with fatal asthma.

Intramuscular or combined intramuscular/intra-arterial administration of bone marrow mononuclear cells: a clinical trial in patients with advanced limb ischemia

AIM

Recent evidence indicates that bone marrow mononuclear cells (BMC) promote collateral vessel formation in patients with severe peripheral arterial disease (PAD). However, aspects concerning optimal administration mode, durability and long-term safety require consideration. Combined intra-arterial (IA) plus intramuscular (IM) BMC delivery may be more effective than exclusive intramuscular injections. The aim of this study was to evaluate feasibility, safety and effect of exclusive IM versus combined IM+IA delivery of autologous BMC in patients who were not candidates for surgical or endovascular treatment.

METHODS

Twenty-seven patients were treated with either combined IA+IM (N=12) or sole IM (N=15) administration of autologous BMC. Efficacy was assessed after 1, 6 and 12 months. Limb salvage, pain-free walking distance, ankle-brachial pressure index (ABI) and pain scores were evaluated.

RESULTS

There were no adverse reactions related to injection of the cells. Three patients died within the first year of follow-up due to non-procedure related causes. Two patients in the IA+IM group required limb amputation because of ongoing critical ischemia versus 7 patients in the IM group (P=0.17). BMC treatment in the remaining patients resulted in a significant and sustained (>12 months) improvement. Pain-free walking distance improved from 81+/-56 meters at baseline to 257+/-126 meters at t=6 months (P=0.0002). Mean ABI increased 23% after 6 months (P=0.01) and pain score reduced for up to 50% as shown by Brief Pain Inventory (P=0.001).

CONCLUSION

Both IM and combined IM/IA delivery of autologous BMC are safe, and result in relevant and sustained improvement in a considerable proportion of patients with severe PAD who are not amenable for conventional treatment.

Postnatal changes in plasma ceruloplasmin and transferrin antioxidant activities in preterm babies

Postnatal changes in plasma ceruloplasmin ferroxidase and transferrin iron-binding antioxidant activity were studied in 10 healthy preterm babies during the first 6 weeks of life. Ceruloplasmin levels and ceruloplasmin ferroxidase activity were low at birth, remained stable for the first 3 weeks, and increased between 3 and 6 weeks. The transferrin levels were also low at birth, and this finding persisted throughout the 6-week study period. However, although the plasma iron-binding antioxidant activity was correspondingly low at birth, it thereafter rose and remained high. In four cord blood samples, but not in subsequent postnatal samples, peroxidation was actually stimulated in the assay measuring plasma iron-binding antioxidant activity. We have previously shown that this phenomenon is probably due to the presence of non-protein-bound iron.

Vitamin E status in preterm infants: assessment by plasma and erythrocyte vitamin E-lipid ratios and hemolysis tests

BACKGROUND

Vitamin E is an essential component of the antioxidant defenses, but supplementation can have side effects in the preterm infant. Careful monitoring of vitamin E status is thus essential, however no consensus has been reached on the best clinical method.

METHODS

In 47 healthy preterm infants, several methods for assessment of vitamin E status were evaluated: plasma and erythrocyte vitamin E levels were measured, vitamin E lipid ratios were calculated, and two variations of the hydrogen peroxide hemolysis test were conducted.

RESULTS

At birth, the plasma and erythrocyte vitamin E levels were low. After birth, the plasma levels rose gradually, whereas the erythrocyte levels remained low. In contrast, the vitamin E-total-lipid ratio was in the low normal range from birth onwards. Vitamin E-lipid ratios using two lipid components (cholesterol with triglycerides, or cholesterol with phospholipids) or one lipid component (cholesterol) correlated with the vitamin E-total-lipid ratio with a good sensitivity and specificity. The susceptibility of erythrocytes to hydrogen peroxide-induced damage (measured as potassium release or malondialdehyde production) was high at birth and declined after birth. However, this susceptibility did not correlate with plasma or erythrocyte vitamin E levels or vitamin E-total-lipid ratio, and the hydrogen peroxide hemolysis test is not a reliable indicator of vitamin E status in preterm infants.

CONCLUSIONS

Our study indicated that a gold standard for clinical assessment of vitamin E status in preterm infants is yet to be found.

Markers of oxidative stress and antioxidant activity in plasma and erythrocytes in neonatal respiratory distress syndrome

Markers of oxidative stress and antioxidant activity in plasma and erythrocytes were studied for 14 d after birth in infants with neonatal respiratory distress syndrome (n = 9) and controls (n = 36). In plasma, the total radical trapping antioxidant capacity and the chain-breaking antioxidants vitamin C, sulfhydryl groups and bilirubin were similar. The differences in uric acid levels were not consistent, but vitamin E levels and vitamin E/total-lipid ratio were lower in the neonatal respiratory distress group (p < 0.01). In erythrocytes, the antioxidant enzymes glutathione peroxidase, glutathione reductase and superoxide dismutase did not differ postnatally. Indicators of oxidative damage in plasma (sulfhydryl/protein ratio and thiobarbituric acid reactive substances) showed the same postnatal course in both groups and were not influenced by oxygen therapy. In erythrocytes the reduced/oxidized glutathione ratio showed no consistent differences. In conclusion, this study, using erythrocytes and plasma, does not provide convincing evidence of oxidative damage and diminished antioxidant defenses in preterm infants with neonatal respiratory distress syndrome.

Measured versus calculated latent iron binding capacity in plasma of newborns

Iron overload as well as iron deficiency may play a role in the pathogenesis of diseases in the newborn and infant and therefore knowledge of the iron status is essential. Using an automated method for the determination of plasma latent iron-binding capacity (LIBC) we measured the LIBC in 20 full term and 20 preterm babies and 20 adults. LIBC was also calculated from transferrin and iron concentration.

Diminished protection against copper-induced lipid peroxidation by cord blood plasma of preterm and term infants

BACKGROUND

Blood plasma of neonates is less able to inhibit iron induced lipid peroxidation than plasma of older patients. Copper, also a powerful pro-oxidant, may accumulate in ill babies because of excess intake or decreased excretion. We assessed in vitro the ability of plasma of neonates to inhibit copper induced peroxidation damage.

METHODS

Peroxidation of phospholipid liposomes, induced by CuCl2, was measured with a thiobarbituric acid assay. The ability of plasma from venous blood of adults and cord blood of babies to inhibit peroxidation was compared. The levels of the copper binding plasma proteins, albumin and ceruloplasmin, were also measured.

RESULTS

Protection against copper induced lipid peroxidation was much higher with adult plasma compared to neonatal plasma. Despite their lower albumin and ceruloplasma levels the protection by the plasma of preterm babies was higher than that of the term babies.

CONCLUSIONS

At birth, babies have a limited ability to inhibit copper induced oxidative damage in vitro. Postnatal studies are needing to assess the influence of maturation and nutrition on these findings and their relevance in diseases induced by reactive oxygen species.

Postnatal changes in plasma chain-breaking antioxidants in healthy preterm infants fed formula and/or human milk

Concentrations of chain-breaking antioxidants were studied in the first 6 postnatal weeks in 29 healthy preterm infants (gestational age 30-35 wk). Vitamin C, uric acid, and sulfhydryl groups declined, whereas vitamin E rose and bilirubin followed its typical biphasic postnatal course. The influence of these changes on the plasma peroxyl radical trapping capacity was assessed in vitro (TRAP assay). The trapping capacity decreased postnatally and this appeared to be related to the coincident fall in uric acid concentrations. Results did not differ between babies fed with only preterm formula (n = 12) and those fed predominantly with human milk (n = 6), except for higher bilirubin and TRAP values in the breast-fed infants. There are major postnatal changes in the concentrations of the plasma chain-breaking antioxidants and this may influence the susceptibility of the preterm baby to oxygen toxicity.

Effect of an exchange transfusion on plasma antioxidants in the newborn

The effect of an exchange transfusion on antioxidants in the plasma of newborns with rhesus hemolytic disease was studied. The antioxidant concentrations in donor blood were similar to normal adult values except for the lower vitamin C concentrations. Exchange transfusion decreased the newborns' iron and ferritin levels and increased their ceruloplasmin and transferrin (primary antioxidants) concentrations and latent iron-binding capacity. The changes in secondary antioxidant concentrations were variable; uric acid and thiols were stable, vitamin C and bilirubin fell, and vitamin E rose. The total peroxyl-radical trapping capacity of the secondary antioxidants did not change significantly. The fall in levels of thiobarbituric acid reactive substances, an index of lipid peroxidation, was related to the lower levels present in the donor blood. Exchange transfusion rapidly produced variable changes in the concentrations of prooxidant and antioxidant substances in plasma and may thus influence free radical metabolism in the newborn.

Limited protection against iron-induced lipid peroxidation by cord blood plasma

The ability of plasma from newborn babies (cord blood) and adults to inhibit iron-induced lipid peroxidation was compared. The caeruloplasmin and transferrin concentrations, and latent iron-binding capacity were lower in the babies (p less than 0.001). The plasma of many of the babies had no latent iron-binding capacity and contained non-protein-bound iron (measured by the bleomycin assay). The in vitro ability of plasma to inhibit iron-induced liposome peroxidation by either ferroxidase antioxidant activity (caeruloplasmin) or iron-binding antioxidant activity (transferrin) was measured. The antioxidant activity in both assays was decreased in the babies (p less than 0.001). The percentage inhibition of peroxidation in the iron-binding antioxidant assay correlated positively with the latent iron-binding capacity (p less than 0.001) and negatively with the presence of bleomycin-detectable iron (p less than 0.02) in the babies. This assay produced stimulation of peroxidation in 42% of the babies but none of the adults. The diminished capacity of cord blood plasma to prevent iron-induced lipid peroxidation may predispose the newborn baby to the toxic effects of oxygen.

Iron overload, free radical damage, and rhesus haemolytic disease

To test the hypothesis that iron overload induces free radical damage in rhesus haemolytic disease (RHD), cord blood plasma of babies with RHD was compared with that of controls matched for gestational age. Babies with RHD had higher ferritin levels, lower latent iron-binding capacity, increased concentrations of lipid-peroxidation products, and low vitamin C levels. Plasma of 3 RHD babies did not inhibit peroxidation stress. These findings, of iron overload and free radical damage, have implications for treatment of RHD.