Cross-sectional relations of multiple inflammatory biomarkers to peripheral arterial disease: The Framingham Offspring Study

Prognostic impact of peripheral artery disease-related parameters in patients with acute coronary syndrome

BACKGROUND

Lower extremity arterial disease (LEAD) and increased aortic stiffness are associated with higher mortality in patients with chronic coronary syndrome, while their prognostic significance after an acute coronary syndrome (ACS) is less known.

METHODS

We analyzed prevalence, clinical phenotypes and association of LEAD - assessed by the ankle-brachial index (ABI) - and increased aortic stiffness - assessed by the aortic pulse wave velocity (PWV) - with all-cause mortality and major adverse cardiovascular events (MACE) in patients admitted with an ACS.

RESULTS

Among 270 patients admitted for ACS (mean age 67 years, 80% males), 41 (15%) had an ABI ≤0.9, with 14 of them (34%) presenting with intermittent claudication (symptomatic LEAD). Patients with symptomatic LEAD, compared with those with asymptomatic LEAD or without LEAD, had higher prevalence of cardiovascular risk factors, lower estimated glomerular filtration rate and higher high-sensitivity C-reactive protein. Patients with LEAD, either symptomatic or asymptomatic, more frequently presented with non-ST-elevation myocardial infarction and more frequently had multivessel coronary artery disease. Both symptomatic and asymptomatic LEAD were significantly associated with all-cause mortality after adjustment for confounders, including multivessel disease or carotid artery disease (hazard ratio 4.03, 95% confidence interval 1.61-10.08, P  < 0.01), whereas PWV was not associated with the outcome in the univariable model. LEAD and PWV were not associated with a higher risk of MACE (myocardial infarction or unstable angina, stroke, or transient ischemic attack).

CONCLUSIONS

LEAD, either clinical or subclinical, but not increased aortic stiffness, is an independent predictor of all-cause mortality in patients admitted for ACS.

Evaluation of systemic immune-inflammation index for predicting severity of lower extremity arterial disease

OBJECTIVE

Predictive value of systemic immune-inflammation index (SII) has been shown in clinical outcomes and complexity of coronary artery disease, acute coronary syndrome, and heart failure. We sight to evaluate value of SII in patients with lower extremity arterial disease (LEAD).

METHODS

A total of 271 patients diagnosed with LEAD were included to our study. Blood samples of the patients were collected and analyzed for biochemical variables and complete blood count parameters. SII value of each patient was calculated. The complexity of atherosclerotic disease was classified according to Trans-Atlantic Inter-Society Consensus (TASC II) classification.

RESULTS

Patients with TASC C-D were older than patients in TASC A-B group (63.06 ± 9.24 years and 60.85 ± 8.75 years, respectively). Other co-morbidities were comparable in both groups. Hemoglobin level and lymphocyte count were significantly lower, neutrophil, platelet counts, and SII values were significantly higher in patients with TASC C-D disease compared to that of patients with TASC A-B disease. SII showed significant correlation with the severity of LEAD (r = 0.363, p < .001). SII value of 664.24 predicted TASC C-D disease with a sensitivity and specificity of 60.8% and 73.3%, respectively. Results of multivariate logistic regression analysis showed that SII had higher odds ratio compared to platelet, neutrophil, and lymphocyte counts.

CONCLUSION

Higher SII may indicate probability of more complex LEAD. This relationship seems plausible in terms of similar pathophysiology of coronary artery disease and peripheral artery disease.

Overcoming big bottlenecks in vascular regeneration

Bioengineering and regenerative medicine strategies are promising for the treatment of vascular diseases. However, current limitations inhibit the ability of these approaches to be translated to clinical practice. Here we summarize some of the big bottlenecks that inhibit vascular regeneration in the disease applications of aortic aneurysms, stroke, and peripheral artery disease. We also describe the bottlenecks preventing three-dimensional bioprinting of vascular networks for tissue engineering applications. Finally, we describe emerging technologies and opportunities to overcome these challenges to advance vascular regeneration.

Multi-Modality Imaging of Atheromatous Plaques in Peripheral Arterial Disease: Integrating Molecular and Imaging Markers

Peripheral artery disease (PAD) is a common and debilitating condition characterized by the narrowing of the limb arteries, primarily due to atherosclerosis. Non-invasive multi-modality imaging approaches using computed tomography (CT), magnetic resonance imaging (MRI), and nuclear imaging have emerged as valuable tools for assessing PAD atheromatous plaques and vessel walls. This review provides an overview of these different imaging techniques, their advantages, limitations, and recent advancements. In addition, this review highlights the importance of molecular markers, including those related to inflammation, endothelial dysfunction, and oxidative stress, in PAD pathophysiology. The potential of integrating molecular and imaging markers for an improved understanding of PAD is also discussed. Despite the promise of this integrative approach, there remain several challenges, including technical limitations in imaging modalities and the need for novel molecular marker discovery and validation. Addressing these challenges and embracing future directions in the field will be essential for maximizing the potential of molecular and imaging markers for improving PAD patient outcomes.

Validating fatty acid binding protein 3 as a diagnostic and prognostic biomarker for peripheral arterial disease: A three-year prospective follow-up study

BACKGROUND

Patients with peripheral arterial disease (PAD) often remain undiagnosed and therefore suboptimally managed. Here, we investigated the diagnostic and prognostic potential of fatty acid binding protein 3 (FABP3) in patients with PAD.

METHODS

In the discovery phase, 374 PAD and 184 non-PAD patients were recruited from vascular surgery ambulatory clinics at St. Michael's Hospital (Toronto, Ontario, Canada) between October 4, 2017 to October 29, 2018. The diagnostic ability of baseline FABP3 level was investigated through receiver operator characteristic (ROC) curves to determine two cutoff points: 1) an exclusionary "rule out" cutoff point, and 2) a confirmatory "rule in" cutoff point. Next, these cutoff points were confirmed in the external validation phase using a separate cohort of 312 patients (180 PAD and 132 non-PAD) recruited from ambulatory vascular surgery clinics at St. Michael's Hospital (Canada) between November 6, 2018-July 30, 2019. Cox regression analyses were used to explore the independent association between FABP3 and major adverse limb events (MALE - defined as need for arterial revascularization or major amputation) and decrease in ankle-brachial index (ABI -defined as drop ≥0.15) during 3 years of follow-up.

FINDINGS

In the discovery phase, FABP3 levels were significantly elevated in patients with PAD compared to non-PAD patients. ROC analysis demonstrated that FABP3 had an AUC of 0.83 (95% CI: 0.81-0.86, p-value < 0.001). FABP3 exclusionary cutoff was <1.55 ng/ml (sensitivity = 96%; specificity = 40%), whereas FABP3 confirmatory cutoff was >3.55 ng/ml (sensitivity = 43%; specificity = 95%) - values that were confirmed in the external validation phase. Cox regression analysis demonstrated FABP3 to be an independent predictor of increase in MALE [HR = 1.14 (1.03-1.29); p-value = 0.010] and worsening PAD status (drop in ABI >0.15 [HR = 1.11 (1.02-1.19); p-value = 0.009]).

INTERPRETATION

Our findings suggested that FABP3 levels can be used as both a diagnostic and prognostic biomarker for PAD, and may facilitate risk stratification in select individuals for purposes of vascular evaluation or intensive medical management.

FUNDING

Funding for this study was provided by the Bill and Vicky Blair Foundation.

Circulating Biomarkers in Lower Extremity Artery Disease

Lower extremity artery disease (LEAD), a chronic condition with disturbed lower extremity circulation due to narrowing of the arteries, is predominantly caused by atherosclerosis and is associated with the presence of cardiovascular risk factors and an increased risk of cardiovascular events. LEAD is prevalent among older individuals and predicted to rise with the ageing population. In progressive disease, the patient experiences symptoms of ischaemia when walking and, in advanced critical limb-threatening ischaemia, even at rest. However, LEAD is asymptomatic in most patients, delaying diagnosis and treatment. In this setting, circulating biomarkers may facilitate earlier diagnosis in selected individuals. This review provides a broad overview of the circulating biomarkers investigated to date in relation to LEAD and discusses their usefulness in clinical practice.

The Role of Early Revascularization and Biomarkers in the Management of Diabetic Foot Ulcers: A Single Center Experience

Diabetic neuropathy and Peripheral Arterial Disease (PAD) are the main etiological factors in foot ulceration. Herein, we report our experience of diabetic foot ulceration (DFU) management, with an analysis of the relationship between the rate of lower extremity amputation, in persons with infected DFU, after revascularization procedures performed to prevent major amputation. This study highlights the role of different biomarkers, showing their usefulness and potentiality in diabetic foot ulcer management, especially for the early diagnosis and therapy effectiveness monitoring. A retrospective analysis, from September 2016 to January 2021, of diabetic patients presenting diabetic foot with DFU, was performed. All patients were treated with at least one vascular procedure (endovascular, open, hybrid procedures) targeting PAD lesions. Outcomes measured were perioperative mortality and morbidity. Freedom from occlusion, primary and secondary patency, and amputation rate were registered. A total of 267 patients, with a mean age of 72.5 years, were included in the study. The major amputation rate was 6.2%, minor amputation rate was 17%. In our experience, extreme revascularization to obtain direct flow reduced the rate of amputations, with an increase in ulcer healing.

X‑irradiation induces acute and early term inflammatory responses in atherosclerosis‑prone ApoE‑/‑ mice and in endothelial cells

Thoracic radiotherapy is an effective treatment for many types of cancer; however it is also associated with an increased risk of developing cardiovascular disease (CVD), appearing mainly ≥10 years after radiation exposure. The present study investigated acute and early term physiological and molecular changes in the cardiovascular system after ionizing radiation exposure. Female and male ApoE^‑/‑ mice received a single exposure of low or high dose X‑ray thoracic irradiation (0.1 and 10 Gy). The level of cholesterol and triglycerides, as well as a large panel of inflammatory markers, were analyzed in serum samples obtained at 24 h and 1 month after irradiation. The secretion of inflammatory markers was further verified in vitro in coronary artery and microvascular endothelial cell lines after exposure to low and high dose of ionizing radiation (0.1 and 5 Gy). Local thoracic irradiation of ApoE^‑/‑ mice increased serum growth differentiation factor‑15 (GDF‑15) and C‑X‑C motif chemokine ligand 10 (CXCL10) levels in both female and male mice 24 h after high dose irradiation, which were also secreted from coronary artery and microvascular endothelial cells in vitro. Sex‑specific responses were observed for triglyceride and cholesterol levels, and some of the assessed inflammatory markers as detailed below. Male ApoE^‑/‑ mice demonstrated elevated intercellular adhesion molecule‑1 and P‑selectin at 24 h, and adiponectin and plasminogen activator inhibitor‑1 at 1 month after irradiation, while female ApoE^‑/‑ mice exhibited decreased monocyte chemoattractant protein‑1 and urokinase‑type plasminogen activator receptor at 24 h, and basic fibroblast growth factor 1 month after irradiation. The inflammatory responses were mainly significant following high dose irradiation, but certain markers showed significant changes after low dose exposure. The present study revealed that acute/early inflammatory responses occurred after low and high dose thoracic irradiation. However, further research is required to elucidate early asymptomatic changes in the cardiovascular system post thoracic X‑irradiation and to investigate whether GDF‑15 and CXCL10 could be considered as potential biomarkers for the early detection of CVD risk in thoracic radiotherapy‑treated patients.

The Role of Circulating Biomarkers in Peripheral Arterial Disease

Peripheral arterial disease (PAD) of the lower extremities is a chronic illness predominantly of atherosclerotic aetiology, associated to traditional cardiovascular (CV) risk factors. It is one of the most prevalent CV conditions worldwide in subjects >65 years, estimated to increase greatly with the aging of the population, becoming a severe socioeconomic problem in the future. The narrowing and thrombotic occlusion of the lower limb arteries impairs the walking function as the disease progresses, increasing the risk of CV events (myocardial infarction and stroke), amputation and death. Despite its poor prognosis, PAD patients are scarcely identified until the disease is advanced, highlighting the need for reliable biomarkers for PAD patient stratification, that might also contribute to define more personalized medical treatments. In this review, we will discuss the usefulness of inflammatory molecules, matrix metalloproteinases (MMPs), and cardiac damage markers, as well as novel components of the liquid biopsy, extracellular vesicles (EVs), and non-coding RNAs for lower limb PAD identification, stratification, and outcome assessment. We will also explore the potential of machine learning methods to build prediction models to refine PAD assessment. In this line, the usefulness of multimarker approaches to evaluate this complex multifactorial disease will be also discussed.

The Proinflammatory Soluble CD40 Ligand Is Associated with the Systemic Extent of Stable Atherosclerosis

Background and objectives: Polyvascular atherosclerosis is frequent and associated with a high cardiovascular risk, although the mechanisms regulating the atherosclerosis extent to single or multiple arterial territories are still poorly understood. Inflammation regulates atherogenesis and soluble CD40 ligand (sCD40L) is an inflammatory mediator associated with the presence of single-territorial atherosclerosis. We assessed whether the sCD40L expression is associated with the atherosclerosis extent to single or multiple arterial territories and with the atherosclerosis severity in different territories. Materials and Methods: We prospectively enrolled 94 participants with no atherosclerosis (controls, n = 26); isolated coronary atherosclerosis (group 1, n = 20); coronary and lower extremity (LE) atherosclerosis (group 2, n = 18); coronary and carotid atherosclerosis (group 3, n = 12); and coronary, LE, and carotid atherosclerosis (group 4, n = 18). Serum sCD40L levels were quantified. Results: The sCD40L levels (ng/mL, mean (standard deviation)) were 4.0 (1.5), 5.6 (2.6), 7.2 (4.2), 5.9 (3.7), and 5.1 (2.4) in controls and groups 1 to 4, respectively (ANOVA p = 0.012). In nonrevascularized patients, the sCD40L levels were significantly higher in group 2 than in group 1 and were correlated with the number of LE diseased segments. Prior LE bypass surgery was associated with lower sCD40L levels. Coexistence of coronary and LE atherosclerosis was independently associated with the sCD40L levels. Conclusions: The sCD40L levels were increased in stable atherosclerosis, particularly in polyvascular coronary and LE atherosclerosis. The number of LE diseased segments and prior LE revascularization were associated with sCD40L expression. To our knowledge, these are novel data, which provide insights into the mechanisms underlying multi-territorial atherosclerosis expression. sCD40L may be a promising noninvasive tool for refining the stratification of the systemic atherosclerotic burden.

Soluble CD40 ligand expression in stable atherosclerosis: A systematic review and meta-analysis

BACKGROUND AND AIMS

The role of inflammation in atherosclerosis development and expression in different arterial territories is unclear. Soluble CD40 ligand (sCD40L) mediates inflammation and atherogenesis. Through a systematic review and meta-analysis, we assessed whether sCD40L was dysregulated in stable atherosclerosis, irrespective of the diseased arterial territory, and whether this dysregulation differed according to the specific territory.

METHODS

Systematic literature searches were performed in MEDLINE, Cochrane Library, Web of Science, and Embase for studies reporting circulating sCD40L levels in individuals with and without stable atherosclerosis. sCD40L levels were compared using random-effects meta-analysis, weighted by the inverse variance method (study protocol: PROSPERO CRD42020181392).

RESULTS

Fifty-four studies (59 estimates) including 7705 patients and 7841 controls were analyzed. sCD40L levels were found to be increased in patients with atherosclerosis, irrespective of the territory (standardized mean difference [SMD] 0.43, 95% CI 0.29-0.57; 59 estimates; χ² heterogeneity p < 0.001; I² = 92%). SMD was greatest in carotid atherosclerosis (SMD 0.58, 95% CI 0.30-0.86; 17 estimates), followed by coronary (SMD 0.43, 95% CI 0.24-0.62; 33 estimates), lower extremity (SMD 0.26, 95% CI -0.02-0.54; 7 estimates), and renal atherosclerosis (SMD -0.07, 95% CI -2.77-2.64; 2 estimates) (χ² heterogeneity p < 0.001; I² ≥ 80% for all). Subgroup analysis revealed that sCD40L levels were increased in clinical, but not subclinical, atherosclerosis.

CONCLUSIONS

sCD40L levels were increased in stable atherosclerosis, particularly in the carotid and coronary territories. These novel data support sCD40L as a marker of systemic atherosclerosis, possibly with differential roles in specific territories.

Fibroblast growth factor 21 in patients with cardiac cachexia: a possible role of chronic inflammation

Aims

Cardiac cachexia is a wasting syndrome characterized by chronic inflammation and high mortality. Fibroblast growth factor 21 (FGF‐21) and monocyte chemoattractant protein 1 (MCP‐1) are associated with cardiovascular disease and systemic inflammation. We investigated FGF‐21 and MCP‐1 in relations to cardiac function, inflammation, and wasting in patients with heart failure with reduced ejection fraction (HFrEF) and cardiac cachexia.

Methods and results

Plasma FGF‐21 and MCP‐1 were measured in a cross‐sectional study among the three study groups: 19 patients with HFrEF with cardiac cachexia, 19 patients with HFrEF without cachexia, and 19 patients with ischaemic heart disease and preserved ejection fraction. Patients with HFrEF and cardiac cachexia displayed higher FGF‐21 levels median (inter quantile range) 381 (232–577) pg/mL than patients with HFrEF without cachexia 224 (179–309) pg/mL and ischaemic heart disease patients 221 (156–308) pg/mL (P = 0.0496). No difference in MCP‐1 levels were found among the groups (P = 0.345). In a multivariable regression analysis, FGF‐21 (logarithm 2) was independently associated with interleukin 6 (logarithm 2) (P = 0.015) and lower muscle mass (P = 0.043), while no relation with N‐terminal pro‐hormone brain natriuretic peptide was observed.

Conclusions

Fibroblast growth factor 21 (FGF‐21) levels were elevated in patients with HFrEF and cardiac cachexia, which could be mediated by increased inflammation and muscle wasting rather than impaired cardiac function.

Inflammation and Peripheral Arterial Disease

Peripheral arterial disease (PAD) is an atherosclerotic disease closely associated with high morbidity and mortality in cardiac events. Inflammation is crucial in atherosclerosis both at triggering and in progression. Numerous inflammatory biomarkers (cytokines, matrix metalloproteinases (MMPs), selectin, intracellular adhesion molecule (ICAM), vascular cell adhesion molecule (VCAM) C-reactive protein (CRP), fibrinogen) have been measured in atherosclerotic diseases including PAD. This paper summarizes the data on the inflammatory biomarkers for PAD pathophysiology and highlights the most useful markers in monitoring PAD outcomes.

Short-term exposure to ambient air pollution and circulating biomarkers of endothelial cell activation: The Framingham Heart Study

BACKGROUND

Short-term exposure to air pollution has been associated with cardiovascular events, potentially by promoting endothelial cell activation and inflammation. A few large-scale studies have examined the associations and have had mixed results.

METHODS

We included 3820 non-current smoking participants (mean age 56 years, 54% women) from the Framingham Offspring cohort examinations 7 (1998-2001) and 8 (2005-2008), and Third Generation cohort examination 1 (2002-2005), who lived within 50 km of a central monitoring station. We calculated the 1- to 7-day moving averages of fine particulate matter (PM_2.5), black carbon (BC), sulfate (SO₄^2-), nitrogen oxides (NO_x), and ozone before examination visits. We used linear mixed effect models for P-selectin, monocyte chemoattractant protein 1 (MCP-1), intercellular adhesion molecule 1, lipoprotein-associated phospholipase A2 activity and mass, and osteoprotegerin that were measured up to twice, and linear regression models for CD40 ligand and interleukin-18 that were measured once, adjusting for demographics, life style and clinical factors, socioeconomic position, time, and meteorology.

RESULTS

We found negative associations of PM_2.5 and BC with P-selectin, of ozone with MCP-1, and of SO₄^2- and NO_x with osteoprotegerin. At the 5-day moving average, a 5 µg/m³ higher PM_2.5 was associated with 1.6% (95% CI: - 2.8, - 0.3) lower levels of P-selectin; a 10 ppb higher ozone was associated with 1.7% (95% CI: - 3.2, - 0.1) lower levels of MCP-1; and a 20 ppb higher NO_x was associated with 2.0% (95% CI: - 3.6, - 0.4) lower levels of osteoprotegerin.

CONCLUSIONS

We did not find evidence of positive associations between short-term air pollution exposure and endothelial cell activation. On the contrary, short-term exposure to higher levels of ambient pollutants were associated with lower levels of P-selectin, MCP-1, and osteoprotegerin in the Framingham Heart Study.

Markers of Atherosclerosis: Part 1 - Serological Markers

Atherosclerosis is a major contributor to morbidity and mortality worldwide. With therapeutic consequences in mind, several risk scores are being used to differentiate individuals with low, intermediate or high cardiovascular (CV) event risk. The most appropriate management of intermediate risk individuals is still not known, therefore, novel biomarkers are being sought to help re-stratify them as low or high risk. This narrative review is presented in two parts. Here, in Part 1, we summarise current knowledge on serum (serological) biomarkers of atherosclerosis. Among novel biomarkers, high sensitivity C-reactive protein (hsCRP) has emerged as the most promising in chronic situations, others need further clinical studies. However, it seems that a combination of serum biomarkers offers more to risk stratification than either biomarker alone. In Part 2, we address genetic and imaging markers of atherosclerosis, as well as other developments relevant to risk prediction.

Prognostic Values of Inflammatory and Redox Status Biomarkers on the Risk of Major Lower-Extremity Artery Disease in Individuals With Type 2 Diabetes

OBJECTIVE

Inflammation and oxidative stress play an important role in the pathogenesis of lower-extremity artery disease (LEAD). We assessed the prognostic values of inflammatory and redox status biomarkers on the risk of LEAD in individuals with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Plasma concentrations of tumor necrosis factor-α receptor 1 (TNFR1), angiopoietin-like 2, ischemia-modified albumin (IMA), fluorescent advanced glycation end products, protein carbonyls, and total reductive capacity of plasma were measured at baseline in the SURDIAGENE (Survie, Diabete de type 2 et Genetique) cohort. Major LEAD was defined as the occurrence during follow-up of peripheral revascularization or lower-limb amputation.

RESULTS

Among 1,412 participants at baseline (men 58.2%, mean [SD] age 64.7 [10.6] years), 112 (7.9%) developed major LEAD during 5.6 years of follow-up. High plasma concentrations of TNFR1 (hazard ratio [95% CI] for second vs. first tertile 1.12 [0.62-2.03; P = 0.71] and third vs. first tertile 2.16 [1.19-3.92; P = 0.01]) and of IMA (2.42 [1.38-4.23; P = 0.002] and 2.04 [1.17-3.57; P = 0.01], respectively) were independently associated with an increased risk of major LEAD. Plasma concentrations of TNFR1 but not IMA yielded incremental information, over traditional risk factors, for the risk of major LEAD as follows: C-statistic change (0.036 [95% CI 0.013-0.059]; P = 0.002), integrated discrimination improvement (0.012 [0.005-0.022]; P < 0.001), continuous net reclassification improvement (NRI) (0.583 [0.294-0.847]; P < 0.001), and categorical NRI (0.171 [0.027-0.317]; P = 0.02).

CONCLUSIONS

Independent associations exist between high plasma TNFR1 or IMA concentrations and increased 5.6-year risk of major LEAD in people with type 2 diabetes. TNFR1 allows incremental prognostic information, suggesting its use as a biomarker for LEAD.

Exercise training in intermittent claudication: Effects on antioxidant genes, inflammatory mediators and proangiogenic progenitor cells

Exercise training remains a therapy of choice in intermittent claudication (IC). However, too exhaustive exercise may cause ischaemic injury and inflammatory response. We tested the impact of three-month treadmill training and single treadmill exercise on antioxidant gene expressions, cytokine concentrations and number of marrow-derived proangiogenic progenitor cells (PPC) in the blood of IC patients. Blood samples of 12 patients were collected before and after training, before and 1, 3 and 6 hours after the single exercise. PPCs were analysed with flow cytometry, cytokine concentrations were checked with Milliplex MAP, while expression of mRNAs and miRNAs was evaluated with qRT-PCR. Treadmill training improved pain-free walking time (from 144 ± 44 seconds [s] to 311 ± 134 s, p=0.02) and maximum walking time (from 578 ± 293 s to 859 ± 423 s, p=0.01) in IC patients. Before, but not after training, the single treadmill exercise increased the number of circulating CD45dimCD34+CD133-KDR+ PPCs (p=0.048), decreased expression of HMOX1 (p=0.04) in circulating leukocytes, reduced tumour necrosis factor-α (p=0.03) and tended to elevate myeloperoxidase (p=0.06) concentrations in plasma. In contrast, total plasminogen activator inhibitor-1 was decreased by single exercise only after, but not before training (p=0.02). Both before and after training the single exercise decreased monocyte chemoattractant protein (MCP)-1 (p=0.006 and p=0.03) concentration and increased SOD1 (p=0.001 and p=0.01) expression. Patients after training had also less interleukin-6 (p=0.03), but more MCP-1 (p=0.04) in the blood. In conclusion, treadmill training improves walking performance of IC patients, attenuates the single exercise-induced changes in gene expressions or PPC mobilisation, but may also lead to higher production of some proinflammatory cytokines.

Elevated Levels of Adhesion Proteins Are Associated With Low Ankle-Brachial Index

Inflammation plays a pivotal role in peripheral artery disease (PAD). Cellular adhesion proteins mediate the interaction of leukocytes with endothelial cells during inflammation. To determine the association of cellular adhesion molecules with ankle-brachial index (ABI) and ABI category (≤1.0 vs >1.0) in a diverse population, 15 adhesion proteins were measured in the Multi-Ethnic Study of Atherosclerosis (MESA). To assess multivariable associations of each protein with ABI and ABI category, linear and logistic regression was used, respectively. Among 2364 participants, 23 presented with poorly compressible arteries (ABI > 1.4) and were excluded and 261 had ABI ≤ 1.0. Adjusting for traditional risk factors, elevated levels of soluble P-selectin, hepatocyte growth factor, and secretory leukocyte protease inhibitor were associated with lower ABI ( P = .0004, .001, and .002, respectively). Per each standard deviation of protein, we found 26%, 20%, and 19% greater odds of lower ABI category ( P = .001, .01, and .02, respectively). Further investigation into the adhesion pathway may shed new light on biological mechanisms implicated in PAD.

Prevalent peripheral arterial disease and inflammatory burden

Background

Strong evidence implicates inflammation in the development of atherosclerotic heart disease but less is known about peripheral arterial disease (PAD). Our objective was to test the hypothesis that a composite index of inflammatory burden is associated with PAD.

Methods

Cross-sectional analysis of a randomly-selected group of 903 community-dwelling men in the MrOS cohort recruited between 2000 and 2002. Using blood samples, we measured seven cytokines and related these levels to prevalent PAD (ankle-brachial index (ABI) <0.9) both individually and as part of an “inflammatory burden score” (a composite sum of the number of pro-inflammatory cytokines in the highest quartile).

Results

Overall, 6.75% of men had ABI <0.9. The odds of prevalent PAD were higher in men with the highest quartile (Q4) levels of interleukin-6 multivariable (MV) adjusted (odds ratio (OR) =3.95 (95% CI, 1.4–11.3), tumor necrosis factor alpha OR = 4.44 (95% confidence interval (CI), 1.5–12.8), and C-reactive protein OR = 3.63 (95% CI, 1.4–9.4) compared to men in Q1. The magnitude of the association of these cytokines with PAD was similar to the effect of being 10 years older, OR = 2.41 (95% CI, 1.16–3.7). These significant effects persisted after additional MV adjustment for smoking except for CRP. Men with the highest inflammatory burden score (≥3) had 3.6 (95% CI, 1.5–8.7) increased odds of PAD, p trend = 0.03. After smoking adjustment the linear trend was borderline statistically significant (p trend = 0.10).

Conclusion

Inflammatory burden is associated with prevalent PAD, an association similar to aging 10 years. The inflammatory effects of smoking contributes to the underlying association between inflammation and PAD.

Comparison of protein-chip array analysis and traditional ELISAs for biomarker detection of diabetic limb arterial stenosis

The aim of this study was to screen the biomarkers of diabetic limb arterial stenosis. Fasting blood samples of 40 patients with diabetic limb arterial stenosis (experimental group), 40 diabetes patients (diabetic control group), and 40 healthy individuals (healthy control group) were collected. Protein-chip assay analysis and ELISA were used to detect tumor necrosis factor α, interleukin-6, endothelin-1, calcitonin gene-related peptide and high-sensitivity C-reactive protein in the three groups. Protein-chip array analysis and ELISA found consistent results that endothelin-1, tumor necrosis factor α, interleukin-6 and high-sensitivity C-reactive protein in the experimental group were significantly up-regulated while the expression of calcitonin gene-related peptide was down-regulated compared with the healthy control group ( P < 0.01). When compared with the diabetic control group, only markedly increased calcitonin gene-related peptide and interleukin-6 were observed in the experimental group ( P < 0.01). The study suggests that high-throughput protein-chip may be a reliable method to screen biomarkers of diabetic limb arterial stenosis. Calcitonin gene-related peptide and interleukin-6 might be promising biomarkers for diabetic limb arterial stenosis.

Lipoprotein-Associated Phospholipase A2 and Incident Peripheral Arterial Disease in Older Adults: The Cardiovascular Health Study

OBJECTIVE

Although prior studies report a relationship between elevated lipoprotein-associated phospholipase A2 (Lp-PLA2) and incident cardiovascular disease, the prospective association of Lp-PLA2 with incident peripheral arterial disease (PAD) has not been studied. We investigated the association between Lp-PLA2 mass and activity and the risk of developing clinical PAD and low ankle-brachial index (ABI).

APPROACH AND RESULTS

Among Cardiovascular Health Study participants, a population-based cohort of 5888 adults aged ≥65 years enrolled in 1989 to 1990, Lp-PLA2 mass and activity were measured in 4537 individuals without baseline PAD. Clinical PAD, defined as leg artery revascularization or diagnosed claudication, was ascertained through 2011. Incident low ABI, defined as ABI <0.9 and decline of ≥0.15, was assessed among 3537 individuals who had an ABI >0.9 at baseline and a second ABI measurement 3 or 6 years later. Analyses were adjusted for demographics, cholesterol, smoking, comorbidities, and C-reactive protein. Each standard deviation increment in Lp-PLA2 mass (117 ng/mL) was associated with a higher risk of developing clinical PAD (hazard ratio 1.28; 95% confidence interval 1.13, 1.45) and incident low ABI (odds ratio 1.16; 95% confidence interval 1.00, 1.33). Results per standard deviation increment in Lp-PLA2 activity (13 nmol/min per mL) were similar for clinical PAD (hazard ratio 1.24; 95% confidence interval 1.07, 1.44) and low ABI (odds ratio 1.28; 95% confidence interval 1.09, 1.50).

CONCLUSIONS

Higher Lp-PLA2 mass and activity were associated with development of both incident clinical PAD and low ABI. Future studies are needed to determine whether pharmacological inhibition of Lp-PLA2 reduces the incidence of PAD.

A review of the pathophysiology and potential biomarkers for peripheral artery disease

Peripheral artery disease (PAD) is due to the blockage of the arteries supplying blood to the lower limbs usually secondary to atherosclerosis. The most severe clinical manifestation of PAD is critical limb ischemia (CLI), which is associated with a risk of limb loss and mortality due to cardiovascular events. Currently CLI is mainly treated by surgical or endovascular revascularization, with few other treatments in routine clinical practice. There are a number of problems with current PAD management strategies, such as the difficulty in selecting the appropriate treatments for individual patients. Many patients undergo repeated attempts at revascularization surgery, but ultimately require an amputation. There is great interest in developing new methods to identify patients who are unlikely to benefit from revascularization and to improve management of patients unsuitable for surgery. Circulating biomarkers that predict the progression of PAD and the response to therapies could assist in the management of patients. This review provides an overview of the pathophysiology of PAD and examines the association between circulating biomarkers and PAD presence, severity and prognosis. While some currently identified circulating markers show promise, further larger studies focused on the clinical value of the biomarkers over existing risk predictors are needed.

Soluble P-selectin predicts lower extremity peripheral artery disease incidence and change in the ankle brachial index: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

To determine the association of circulating P-selectin with prevalent and incident peripheral artery disease (PAD), the ankle brachial index (ABI), and change in the ABI.

METHODS

The Multi-Ethnic Study of Atherosclerosis (MESA) is a prospective population-based cohort study including 6814 European descent, African American, Hispanic and Chinese men and women aged 45-84 at baseline. Four clinical exams took place after the baseline exam. After excluding those with ABI>1.4, prevalent and incident PAD were defined as an ABI≤0.90. ABI progression was defined as progression from a normal ABI (0.91-1.4) to abnormal (≤0.90 or >1.4) at a later exam.

RESULTS

In adjusted models, each SD (13 ng/mL) higher P-selectin was significantly associated with 0.007 lower ABI (95% CI ((-0.011, -0.004)), p < 0.001), and an average change in the ABI of -0.006 ((-0.010, -0.003, p < 0.001). P-selectin was significantly associated with a 1.17-fold greater odds of prevalent PAD ((1.02, 1.33), p = 0.03), and a 30% greater risk of incident PAD ((1.11, 1.53), p = 0.001), as well as progression from a normal ABI to an ABI≤ 0.90 (p = 0.003), but not to an ABI>1.4 (p = 0.96). Addition of P-selectin to models containing traditional PAD risk factors and markers of inflammation/coagulation significantly improved the net reclassification for ABI progression (p = 0.03), but was only marginally significant for incident PAD (p = 0.06).

CONCLUSIONS

P-selectin is significantly associated with the development of PAD. However, further research is needed in population-based studies to confirm prospective associations of P-selectin with incident PAD and change in the ABI, as well as its potential predictive ability.

Impact of peripheral artery disease on prognosis in hospitalized heart failure patients

BACKGROUND

The impact of peripheral artery disease (PAD) on heart failure (HF) prognosis remains unclear.

METHODS AND RESULTS

A total of 388 consecutive decompensated HF patients were divided into 2 groups based on the presence of PAD: HF with PAD (PAD group, n=101, 26.0%) and HF without PAD (non-PAD group, n=287, 74.0%). We compared clinical features, echocardiographic parameters, cardiopulmonary exercise testing results, laboratory findings, as well as cardiac, non-cardiac, and all-cause mortality between the 2 groups. The PAD group, as compared with the non-PAD group, had (1) higher prevalence of coronary artery disease (40.6 vs. 27.5%, P=0.011) and cerebrovascular disease (34.7 vs. 18.2%, P=0.001); (2) higher tumor necrosis factor-α (1.82 vs. 1.49 pg/ml, P=0.023), C-reactive protein (0.32 vs. 0.19 mg/dl, P=0.045), and troponin T (0.039 vs. 0.021 ng/ml, P=0.019); (3) lower LVEF (42.4 vs. 48.5%, P<0.001); (4) lower peak V̇O2(13.4 vs. 15.9 ml·kg(-1)·min(-1), P=0.001); and (5) higher V̇E/V̇CO2slope (38.8 vs. 33.7, P<0.001). On Kaplan-Meier analysis, cardiac, non-cardiac, and all-cause mortality were significantly higher in the PAD group than in the non-PAD group (P<0.05, respectively). On Cox proportional hazard analysis after adjusting for confounding factors, PAD was an independent predictor of cardiac and all-cause mortality (P<0.05, respectively) in HF patients.

CONCLUSIONS

PAD was common and an independent predictor of cardiac and all-cause mortality in HF patients.

Understanding the role of circulating chemokine (C-C motif) ligand 2 in patients with chronic ischemia threatening the lower extremities

The role of chemokine (C-C motif) ligand 2 (CCL2) in peripheral artery disease is unclear. We measured the difference between serum and plasma levels of CCL2 in patients with chronic ischemia threatening the lower extremities following the observation that atypical chemokine receptors in blood and tissue cells may prevent CCL2 from entering the circulation and consequently modulate its function of attracting monocytes to the site of lesion. To identify the influence of CCL2, we compared the patients' values to those in bio-banked samples from a control population. Further, we explored the association with the Asp42Gly polymorphism (rs12075) in Duffy antigen chemokine receptor; one of these atypical chemokine receptors. When possible, we evaluated in surgically excised normal and affected arteries the calcium burden as well as the expression of CCL2 and related receptors reflecting the inflammatory status. Our findings indicate that circulating CCL2 was significantly associated with the severity and presence of the disease (OR 0.966, 95% CI 0.944 to 0.988, p = 0.003). Circulating CCL2 was dependent on the rs12075 genotype (AA>AG>GG), which, probably, indicates a higher expression of chemokine receptor in the arteries of AA subjects. The associations with genetic variants and the over-expression of atypical chemokine receptors in diseased arteries may have potential implications and our data indicate that CCL2 may represent a previously unrecognized factor that needs to be considered in the screening of patients with risk factors for peripheral artery disease.

Increased calcification in osteoprotegerin-deficient smooth muscle cells: Dependence on receptor activator of NF-κB ligand and interleukin 6

OBJECTIVE

Vascular calcification is highly correlated with cardiovascular disease morbidity and mortality. Osteoprotegerin (OPG) is a secreted decoy receptor for receptor activator of NF-κB ligand (RANKL). Inactivation of OPG in apolipoprotein E-deficient (ApoE-/-) mice increases lesion size and calcification. The mechanism(s) by which OPG is atheroprotective and anticalcific have not been entirely determined. We investigated whether OPG-deficient vascular smooth muscle cells (VSMCs) are more susceptible to mineralization and whether RANKL mediates this process.

RESULTS

Lesion-free aortas from 12-week-old ApoE-/-OPG-/- mice had spotty calcification, an appearance of osteochondrogenic factors and a decrease of smooth muscle markers when compared to ApoE-/-OPG+/+ aortas. In osteogenic conditions, VSMCs isolated from ApoE-/-OPG-/- (KO-VSMC) mice deposited more calcium than VSMCs isolated from ApoE-/-OPG+/+ (WT-VSMC) mice. Gene expression and biochemical analysis indicated accelerated osteochondrogenic differentiation. Ablation of RANKL signaling in KO-VSMCs rescued the accelerated calcification. While WT-VSMCs did not respond to RANKL treatment, KO-VSMCs responded with enhanced calcification and the upregulation of osteochondrogenic genes. RANKL strongly induced interleukin 6 (IL-6), which partially mediated RANKL-dependent calcification and gene expression in KO-VSMCs.

CONCLUSIONS

OPG inhibits vascular calcification by regulating the procalcific effects of RANKL on VSMCs and is thus a possible target for therapeutic intervention.

Atherosclerotic biomarkers and aortic atherosclerosis by cardiovascular magnetic resonance imaging in the Framingham Heart Study

BACKGROUND

The relations between subclinical atherosclerosis and inflammatory biomarkers have generated intense interest but their significance remains unclear. We sought to determine the association between a panel of biomarkers and subclinical aortic atherosclerosis in a community-based cohort.

METHODS AND RESULTS

We evaluated 1547 participants of the Framingham Heart Study Offspring cohort who attended the 7th examination cycle and underwent both cardiovascular magnetic resonance imaging (CMR) and assays for 10 biomarkers associated with atherosclerosis: high-sensitivity C-reactive protein, fibrinogen, intercellular adhesion molecule-1, interleukin-6, interleukin-18, lipoprotein-associated phospholipase-A2 activity and mass, monocyte chemoattractant protein-1, P-selectin, and tumor necrosis factor receptor-2. In logistic regression analysis, we found no significant association between the biomarker panel and the presence of aortic plaque (global P=0.53). Using Tobit regression with aortic plaque as a continuous variable, we noted a modest association between biomarker panel and aortic plaque volume in age- and sex-adjusted analyses (P=0.003). However, this association was attenuated after further adjustment for clinical covariates (P=0.09).

CONCLUSIONS

In our community-based cohort, we found no significant association between our multibiomarker panel and aortic plaque. Our results underscore the strengths and limitations of the use of biomarkers for the identification of subclinical atherosclerosis and the importance of traditional risk factors.

Anemia and type 2 diabetes mellitus associated with peripheral arterial disease progression in Chinese male patients

OBJECTIVE

Peripheral arterial disease (PAD) is a chronic occlusive disease mainly occurred in elderly adults. Arteriosclerosis obliterans (ASO) mainly occurring from small or medium sized arteries of the lower extremities is one of the most common causes of PAD. The gender-related differences of circulating risk factors in diabetic patients with ASO in China remain unknown. The aim of this study is to investigate the gender-related differences in the pattern of several potential risk factors between male and female patients with ASO and type 2 diabetes mellitus (T2D).

DESIGN AND METHODS

Clinical profiles and risk factors were analyzed in 323 Chinese patients with ASO and 112 patients were confirmed with T2D. Severities of limb ischemia were staged according to Fontaine classification.

RESULTS

The significant inverse correlation was seen between the increased age and hemoglobin. The significant positive correlation was seen between the increased age, urea and creatinine both in the non-diabetic and diabetic male patients. The expression levels of hemoglobin significantly correlate with the classification of Fontaine clinical symptoms in Chinese male patients with T2D/ASO.

CONCLUSION

The study is the first report indicating that the gender-related differences of circulating risk factors are associated with T2D patients with ASO in China. Anemia in Chinese male patients with T2D/ASO may play an important role in peripheral arterial disease progression.

Multiple inflammatory biomarkers in relation to cardiovascular events and mortality in the community

OBJECTIVE

Evidence suggests that chronic low-grade inflammation and oxidative stress are related to cardiovascular disease (CVD) and mortality.

APPROACH AND RESULTS

We examined 11 established and novel biomarkers representing inflammation and oxidative stress (C-reactive protein, fibrinogen, interleukin-6, intercellular adhesion molecule-1, lipoprotein-associated phospholipase-A2 [mass and activity], monocyte chemoattractant protein-1, myeloperoxidase, CD40 ligand, P-selectin, and tumor necrosis factor receptor II [TNFRII]) in relation to incident major CVD and mortality in the community. We studied 3035 participants (mean age, 61 ± 9 years; 53% women). During follow-up (median, 8.9 years), 253 participants experienced a CVD event and 343 died. C-reactive protein (hazard ratio [HR] reported per SD ln-transformed biomarker, 1.18; 95% confidence interval [CI], 1.02-1.35; nominal P=0.02) and TNFRII (HR, 1.15; 95% CI, 1.01-1.32; nominal P=0.04) were retained in multivariable-adjusted models for major CVD, but were not significant after adjustment for multiple testing. The biomarkers related to mortality were TNFRII (HR, 1.33; 95% CI, 1.19-1.49; P<0.0001), ICAM-1 (HR, 1.24; 95% CI, 1.12-1.37; P<0.0001), and interleukin-6 (HR, 1.25; 95% CI, 1.12-1.39; P<0.0001). The addition of these markers to the model, including traditional risk factors, increased discrimination and reclassification for risk of death (P<0.0001), but not for CVD.

CONCLUSIONS

Of 11 inflammatory biomarkers tumor necrosis factor receptor II was related to cardiovascular disease and mortality in the Framingham Heart Study. The combination of TNFRII with C-reactive protein in relation to CVD and with interleukin-6 to mortality increased the predictive ability in addition to CVD risk factors for total mortality but not for incident CVD.

Clinical correlates of change in inflammatory biomarkers: The Framingham Heart Study

OBJECTIVES

Traditional clinical risk factors are associated with inflammation cross-sectionally, but associations of longitudinal variation in inflammatory biomarkers with corresponding changes in clinical risk factors are incompletely described. We sought to analyze clinical factors associated with change in inflammation in the community.

METHODS

We studied 3013 Framingham Offspring (n = 2735) and Omni Cohort (n = 278) participants (mean age 59 years, 55% women, 9% ethnic/racial minority) who attended two consecutive examination cycles (mean 6.7 years apart). We selected ten inflammatory biomarkers representing distinctive biological functions: C-reactive protein (CRP), intercellular adhesion molecule-1, interleukin-6, isoprostanes, lipoprotein-associated phospholipase-2 (Lp-PLA2) activity, Lp-PLA2-mass, monocyte chemoattractant protein-1, osteoprotegerin, P-selectin, and tumor necrosis factor receptor II (TNFRII). We constructed multivariable-adjusted regression models to assess the relations of baseline, follow-up and change in clinical risk factors with change in biomarker concentrations over time.

RESULTS

Baseline, follow-up and change in clinical risk factors explain a moderate amount of the variation in biomarker concentrations across 2 consecutive examinations (ranging from r(2) = 0.28 [TNFRII] up to 0.52 [Lp-PLA2-mass]). In multivariable models, increasing body-mass index, smoking initiation, worsening lipid profile, and increasing waist size were associated with increasing concentrations of several biomarkers. Conversely, hypercholesterolemia therapy and hormone replacement cessation were associated with decreasing concentrations of biomarkers such as CRP, Lp-PLA2-mass and activity.

CONCLUSION

Cardiovascular risk factors have different patterns of association with longitudinal change in inflammatory biomarkers and explain modest amounts of variability in biomarker concentrations. Nevertheless, a substantial proportion of longitudinal change in inflammatory markers is not explained by traditional risk factors.

Associations of candidate biomarkers of vascular disease with the ankle-brachial index and peripheral arterial disease

BACKGROUND

The use of multiple biomarkers representing various etiologic pathways of atherosclerosis may improve the prediction of interindividual variation in the ankle-brachial index (ABI). To this end, we investigated associations of 47 candidate biomarkers with the ABI and presence of peripheral arterial disease (PAD) in African-Americans (AAs) and non-Hispanic whites (NHWs).

METHODS

Study participants included 1,291 AAs (71.1% women, mean age, 63.4±9.3 years) and 1,152 NHWs (57.5% women, mean age 58.5±10.1 years) belonging to hypertensive sibships. Peripheral arterial disease was defined as an ABI ≤ 0.90. Circulating levels of 47 candidate biomarkers were log-transformed before analysis because of skewed distribution. Multivariate regression analyses were used to identify biomarkers associated with ABI or PAD independently of age, sex, conventional risk factors, and medication use.

RESULTS

After adjustment for covariates, higher levels of nine biomarkers were associated with a lower ABI in AAs (all P ≤ 0.005); these biomarkers were C-reactive protein (CRP), interleukin-6, tumor necrosis factor receptor-II (TNF-R II), lipoprotein(a), N-terminal pro-brain natriuretic peptide (NT-proBNP), pro-atrial natriuretic peptide, C-terminal pro-arginine vasopressin, osteoprotegerin, and fibrinogen. Three biomarkers - myeloperoxidase, NT-proBNP, and D-dimer - were associated with ABI in NHWs (all P ≤ 0.01). C-reactive protein, interleukin-6, TNF-R II, lipoprotein(a), NT-proBNP, pro-atrial natriuretic peptide, D-dimer, and fibrinogen were associated with PAD (all P ≤ 0.005) in AAs after adjustment for covariates. None of the biomarkers were independently associated with PAD in NHWs.

CONCLUSION

A multimarker approach improved the prediction of interindividual variation in the ABI in AAs and NHWs, and improved prediction of the presence of PAD in AAs.

Long term prognostic value of subclinical carotid and femoral arterial wall lesions in patients with ST-elevation-myocardial infarction having percutaneous coronary intervention

The presence of clinical peripheral arterial disease (PAD) is associated with an increased risk for adverse cardiovascular outcomes in patients with coronary artery disease. However, there are few data regarding the impact of the presence and degree of the subclinical PAD on outcomes in patients with coronary artery disease. The aim of this study was to assess prospectively the grade of subclinical PAD in the setting of patients who underwent primary percutaneous coronary intervention for the prediction of intermediate- and long-term clinical outcomes. A total of 971 consecutive patients without histories of clinical PAD who under went primary percutaneous coronary intervention for ST-segment elevation myocardial infarction were included in a prospective follow-up. Subclinical PAD severity was blindly assessed on the basis of an ultrasound arterial morphologic classification defined with the assessment of wall carotid and femoral artery bifurcations. This classification included 4 increasing classes of subclinical carotid and femoral arterial wall lesions, and the total group was divided accordingly. Death and major cardiovascular and cerebrovascular events were evaluated. During a median follow-up period of 40 months, a total of 109 patients (11.2%) died, 9 (2.8%) in class I, 12 (3.1%) in class II, 37 (23.7%) in class III, and 51 (49.0%) in class IV (p <0.001). On multivariate analysis, mortality in class IV was sevenfold higher (hazard ratio [HR] 7.34, 95% confidence interval [CI] 3.3 to 16.33, p <0.001) compared to class I and was also increased in class III (HR 5.38, 95% CI 2.42 to 11.92, p <0.001). Similar results were obtained for major adverse cardiovascular and cerebrovascular events in class IV (HR 7.50, 95% confidence interval 5.36 to 10.50, p <0.0001), class III (HR 6.44, 95% CI 4.45 to 9.32, p <0.001), and class II (HR 1.73, 95% CI 1.23 to 2.43, p = 0.002). In conclusion, ultrasound arterial morphologic classification may be applied in patients with ST-segment elevation myocardial infarctions who undergo primary percutaneous coronary intervention and can stratify patients for poor clinical outcomes during long-term follow-up.

Ethnic differences in ankle brachial index are present in middle-aged individuals without peripheral arterial disease

INTRODUCTION

To better understand the basis for previously reported ethnic differences in ankle brachial index (ABI), we investigated whether these differences were present in individuals without known peripheral arterial disease (PAD).

METHODS

We used data from National Health and Nutrition Examination surveys (NHANES 1999-2004) to determine whether ethnic differences were present in respondents without PAD (1 ≤ ABI ≤ 1.3). We assessed whether ethnicity was an independent predictor of ABI and ankle systolic blood pressure (SBP) in linear regression models that adjusted for conventional and novel cardiovascular risk factors. To minimize effects of atherosclerosis on ABI, we studied adults aged ≤ 60 years, and also repeated our analyses in a subset aged ≤ 50 years that did not have risk factors for PAD.

RESULTS

3348 participants aged ≤ 60 years were included in the study. Mean ABI was 1.11 in non-Hispanic Blacks (NHB) and 1.13 in non-Hispanic Whites (NHW) (P < 0.0001). In multivariable linear regression analysis that adjusted for age, gender, ethnicity, smoking, height, diabetes, brachial SBP, dyslipidemia, diabetes, renal function, concurrent cardiovascular disease, and plasma levels of homocysteine, fibrinogen and C-reactive protein, NHB had lower ABI than NHW (β = -0.03 ± 0.004, P < 0.00001). Although, NHBs had higher ankle SBP than NHWs (by 5.4 mm Hg), NHBs had a lower mean ankle SBP (β = -3.663 mm Hg ± 0.500, P < 0.0001) after adjusting for clinical covariates, including brachial SBP, in multivariable analysis.

CONCLUSION

Ethnic differences in ABI are present in middle-aged adults at low risk for peripheral atherosclerosis.

Low ankle-brachial index and the development of rapid estimated GFR decline and CKD

BACKGROUND

Low ankle-brachial index (ABI) is associated with increases in serum creatinine level. Whether low ABI is associated with the development of rapid estimated glomerular filtration rate (eGFR) decline, stage 3 chronic kidney disease (CKD), or microalbuminuria is uncertain.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Framingham Offspring cohort participants who attended the sixth (1995-1998) and eighth (2005-2008) examinations.

PREDICTOR

ABI, categorized as normal (>1.1 to <1.4), low-normal (>0.9 to 1.1), and low (≤0.9).

OUTCOMES

Rapid eGFR decline (eGFR decline ≥3 mL/min/1.73 m(2) per year), incident stage 3 CKD (eGFR <60 mL/min/1.73 m(2)), incident microalbuminuria.

MEASUREMENTS

GFR was estimated using the serum creatinine-based CKD-EPI (CKD Epidemiology Collaboration) equation. Urinary albumin-creatinine ratio (UACR) was determined based on spot urine samples.

RESULTS

During 9.5 years, 9.0% (232 of 2,592) experienced rapid eGFR decline and 11.1% (270 of 2,426) developed stage 3 CKD. Compared to normal ABI, low ABI was associated with 5.73-fold increased odds of rapid eGFR decline (95% CI, 2.77-11.85; P<0.001) after age, sex, and baseline eGFR adjustment; this persisted after multivariable adjustment for standard CKD risk factors (OR, 3.60; 95% CI, 1.65-7.87; P = 0.001). After adjustment for age, sex, and baseline eGFR, low ABI was associated with a 2.51-fold increased odds of stage 3 CKD (OR, 2.51; 95% CI, 1.16-5.44; P = 0.02), although this was attenuated after multivariable adjustment (OR, 1.68; 95% CI, 0.75-3.76; P = 0.2). In 1,902 free of baseline microalbuminuria, low ABI was associated with increased odds of microalbuminuria after adjustment for age, sex, and baseline UACR (OR, 2.81; 95% CI, 1.07-7.37; P = 0.04), with attenuation upon further adjustment (OR, 1.88; P = 0.1).

LIMITATIONS

Limited number of events with low ABI. Outcomes based on single serum creatinine and UACR measurements at each examination.

CONCLUSIONS

Low ABI is associated with an increased risk of rapid eGFR decline, suggesting that systemic atherosclerosis predicts a decrease in kidney function.

Patients with unrecognized peripheral arterial disease (PAD) assessed by ankle-brachial index (ABI) present a defined profile of proinflammatory markers compared to healthy subjects

BACKGROUND

Many studies have postulated that atherosclerosis should be considered as an inflammatory disease. In addition, some studies have focused on the relationship between inflammation and peripheral arterial disease (PAD).

OBJECTIVE

Define the plasma levels of soluble markers, including the proinflammatory cytokine interleukin-6 (IL-6), the anti-inflammatory cytokine transforming growth factor-β1 (TGF-β1), the endothelial-specific adhesion factor (E-selectin) and two proteinases involved in extracellular matrix degradation (matrix metalloproteinases-2 and -9, MMP-2, and MMP-9) in previously unrecognized patients with peripheral artery disease (PAD) and non-PAD controls.

RESULTS

Significantly higher levels of IL-6, E-selectin and MMP-2/MMP-9 and significantly reduced levels of TGF-β1 were found in PAD patients (ankle-brachial index, ABI⩽0.9) compared to non-PAD control subjects (1.4>ABI>0.9).

CONCLUSION

The results demonstrated the subjects with unrecognized PAD (ABI⩽0.9) show a characteristic phlogistic pattern differently from healthy subjects and it strongly supports the pivotal role played by inflammatory and immunological mechanisms in the initiation and progression of the atherosclerotic process in peripheral arteries. These biomarkers could be helpful to screen the susceptibility for the diseases in peripheral arteries.

Evaluation of serum adipokines in peripheral arterial occlusive disease

Aim. Out study aimed to assess the serum levels of adipokines in patients with peripheral arterial occlusive disease (PAOD) caused by atherosclerosis. Methods. Serum samples were obtained from 221 patients. One hundred and forty patients, (26 females and 114 males) met the inclusion criteria and were assigned into the case group. Eighty one patients (17 females and 64 males), were included in the control group. Circulating plasma levels of adiponectin, leptin, resistin, and TNF-α were measured using the enzyme-linked immunosorbent assay (ELISA) method. Results. Significant lower levels of adiponectin were present (P = 0.0061) in PAOD patients (2380.23 ± 1634.42 pg/mL) compared to the control group (3065.06 ± 1901.2 pg/mL). The mean value of leptin (2844.42 ± 3301.08 pg/mL) and resistin (2047.81±3301.08 pg/mL) patients included in the PAOD group was higher, as compared to the control group. Statistically significant difference was found between the two groups for leptin (P = 0.0332) and for resistin (P = 0.0352). No statistically significant difference for TNF-α was found between the two groups (P > 0.05). Conclusion. The markers of inflammation secreted by the adipose tissue (adiponectin, leptin, resistin) showed significant differences in patients from the case group (with PAOD) compared to the control group.

Epoxyeicosatrienoic acids and heme oxygenase-1 interaction attenuates diabetes and metabolic syndrome complications

MSCs are considered to be the natural precursors to adipocyte development through the process of adipogenesis. A link has been established between decreased protective effects of EETs or HO-1 and their interaction in metabolic syndrome. Decreases in HO-1 or EET were associated with an increase in adipocyte stem cell differentiation and increased levels of inflammatory cytokines. EET agonist (AKR-I-27-28) inhibited MSC-derived adipocytes and decreased the levels of inflammatory cytokines. We further describe the role of CYP-epoxygenase expression, HO expression, and circulating cytokine levels in an obese mouse, ob/ob(-/-) mouse model. Ex vivo measurements of EET expression within MSCs derived from ob/ob(-/-) showed decreased levels of EETs that were increased by HO induction. This review demonstrates that suppression of HO and EET systems exist in MSCs prior to the development of adipocyte dysfunction. Further, adipocyte dysfunction can be ameliorated by induction of HO-1 and CYP-epoxygenase, i.e. EET.

IκBNS regulates interleukin-6 production and inhibits neointimal formation after vascular injury in mice

AIMS

IκBNS regulates a subset of Toll-like receptor (TLR)-dependent genes including interleukin-6 (IL-6) by inhibiting nuclear factor-κB (NF-κB). IL-6 is an inflammatory biomarker for cardiovascular diseases. The aim of this study was to determine whether IκBNS changes arterial inflammation and intimal hyperplasia after vascular injury.

METHODS AND RESULTS

We investigated neointimal formation in IκBNS-deficient (IκBNS(-/-); C57BL/6 background) and wild-type (IκBNS(+/+)) mice 2 weeks after cuff injury. The mean intimal area and the intima/media ratio of IκBNS(-/-) mice increased 89% (8066 ± 1141 vs. 4267 ± 1095 μm(2); P = 0.027) and 100% (0.72 ± 0.13 vs. 0.36 ± 0.09; P = 0.032) compared with IκBNS(+/+) mice. We observed significant up-regulation of TLR4 in injured arteries of IκBNS(-/-) mice. NF-κB activity in the intima of IκBNS(-/-) mice was 5.1-fold higher (P = 0.008) compared with IκBNS(+/+) mice at 7 days post-injury. IL-6 mRNA levels in injured arteries of IκBNS(-/-) mice were 1.8-fold higher (P = 0.002) compared with those of IκBNS(+/+) mice at 3 days post-injury. Vascular smooth muscle cells from IκBNS(-/-) mice showed a significant increase in cell migration compared with those from IκBNS(+/+) mice after IL-6 stimulation in the scratch-wound healing assay. Furthermore, anti-mouse IL-6 receptor antibody (MR16-1) significantly reduced intimal hyperplasia compared with control IgG injection in IκBNS(-/-) mice. These findings suggest that IL-6 participates in the development of neointimal hyperplasia after vascular injury in IκBNS(-/-) mice.

CONCLUSION

IκBNS down-regulates TLR4 expression, NF-κB activity, and IL-6 production after vascular injury. IκBNS might suppress intimal hyperplasia caused by vascular inflammation such as atherosclerosis, and restenosis after angioplasty.

Inflammatory markers in population studies of aging

PURPOSE

To review findings from major epidemiologic studies regarding risk factors for and consequences of elevated markers of inflammation in older adults.

RESULTS

Most large, current epidemiologic studies of older adults have measured serum interleukin-6 (IL-6), C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-alpha) and some studies also include more extensive batteries of measures including soluble receptors. There are few defined risk factors for the modest elevations in inflammatory markers seen with aging. These include visceral adiposity, lower sex steroid hormones, smoking, depression and periodontal disease. Of the markers assessed, IL-6 is most robustly associated with incident disease, disability and mortality.

CONCLUSION

Though correlated with age, the etiology of elevated inflammatory markers remains incompletely defined. Inflammation, especially IL-6 may be a common cause of multiple age-related diseases or a final common pathway by which disease leads to disability and adverse outcomes in older adults. Future research targeting inflammation should examine these pathways.

Peripheral artery disease. Part 1: clinical evaluation and noninvasive diagnosis

Peripheral artery disease (PAD) is a marker of systemic atherosclerosis. Most patients with PAD also have concomitant coronary artery disease (CAD), and a large burden of morbidity and mortality in patients with PAD is related to myocardial infarction, ischemic stroke, and cardiovascular death. PAD patients without clinical evidence of CAD have the same relative risk of death from cardiac or cerebrovascular causes as those diagnosed with prior CAD, consistent with the systemic nature of the disease. The same risk factors that contribute to CAD and cerebrovascular disease also lead to the development of PAD. Because of the high prevalence of asymptomatic disease and because only a small percentage of PAD patients present with classic claudication, PAD is frequently underdiagnosed and thus undertreated. Health care providers may have difficulty differentiating PAD from other diseases affecting the limb, such as arthritis, spinal stenosis or venous disease. In Part 1 of this Review, we explain the epidemiology of and risk factors for PAD, and discuss the clinical presentation and diagnostic evaluation of patients with this condition.

Adipocyte heme oxygenase-1 induction attenuates metabolic syndrome in both male and female obese mice

Increases in visceral fat are associated with increased inflammation, dyslipidemia, insulin resistance, glucose intolerance, and vascular dysfunction. We examined the effect of the potent heme oxygenase (HO)-1 inducer, cobalt protoporphyrin (CoPP), on regulation of adiposity and glucose levels in both female and male obese mice. Both lean and obese mice were administered CoPP intraperitoneally (3 mg/kg once per week) for 6 weeks. Serum levels of adiponectin, tumor necrosis factor α (TNFa), interleukin (IL)-1β and IL-6, and HO-1, PPARγ, pAKT, and pAMPK protein expression in adipocytes and vascular tissue were measured. While female obese mice continued to gain weight at a rate similar to controls, induction of HO-1 slowed the rate of weight gain in male obese mice. HO-1 induction led to lowered blood pressure levels in obese male and female mice similar to that of lean male and female mice. HO-1 induction also produced a significant decrease in the plasma levels of IL-6, TNFα, IL-1β, and fasting glucose of obese females compared to untreated female obese mice. HO-1 induction increased the number and decreased the size of adipocytes of obese animals. HO-1 induction increased adiponectin, pAKT, pAMPK, and PPARγ levels in adipocyte of obese animals. Induction of HO-1 in adipocytes was associated with an increase in adiponectin and a reduction in inflammatory cytokines. These findings offer the possibility of treating not only hypertension, but also other detrimental metabolic consequences of obesity including insulin resistance and dyslipidemia in obese populations by induction of HO-1 in adipocytes.

Tumor necrosis factor-alpha serum levels in healthy smokers and nonsmokers

Background:

Tobacco smoking is the most important risk factor for chronic obstructive pulmonary disease (COPD) development. Inhaled cigarette smoke can induce tumor necrosis factor-α (TNF-α) production by alveolar macrophages, which in turn may enhance the production of metalloproteinases (MMPs). MMPs have been involved in mediating airway inflammation and lung destruction.

Objectives:

We aimed to measure the TNF-α serum levels in healthy heavy smokers and healthy nonsmokers to determine the dose-response relationship based on the cigarette smoke exposure.

Subjects and methods:

We included in our study 43 healthy heavy smokers and 19 healthy nonsmokers (the control group). The smokers group was classified as less than one pack, one pack, and more than one pack per day. A clinical and paraclinical evaluation was performed in both groups, without any evidence of infection or COPD. The serum levels of TNF-α were assessed by ELISA.

Results:

The TNF-α serum levels were significantly higher for the group of smokers compared to the group of nonsmokers (P < 0.004). We also noticed an increased TNF-α concentration in the serum of smokers with more than one pack per day compared with those with less than one pack per day (P < 0.03). There was a positive correlation between the serum level of TNF-α and tobacco smoke exposure.

Conclusions:

The high levels of TNF-α in the serum of smokers suggest an imbalance between the proinflammatory and anti-inflammatory factors as a result of tobacco smoke exposure. The concentration of TNF-α is elevated in the serum of healthy heavy smokers in a cigarette dose-dependent manner. We speculate that the serum level of TNF-α might be a useful biomarker for the selection of heavy smokers with a high risk of developing smoke induced pulmonary diseases.

Biomarkers of peripheral arterial disease

Atherosclerotic arterial occlusive disease affecting the lower extremities is also known as peripheral artery disease (PAD). This disorder affects 8 to 12 million individuals in the U.S. and is increasingly prevalent in Europe and Asia. Unfortunately, most patients are not diagnosed and are not optimally treated. A blood test for PAD, if sufficiently sensitive and specific, would be expected to improve recognition and treatment of these individuals. Even a biomarker panel of moderate sensitivity and specificity for PAD could refine risk stratification to select individuals for diagnostic vascular examination. Alternatively, biomarkers for PAD may be useful in determining prognosis, the risk for progression, or the response to therapy. Finally, the discovery of biomarkers associated with PAD may provide novel insights into the pathophysiology of PAD and new therapeutic avenues to pursue. Biomarkers may be derived from studies of the genome, transcriptome, proteome, or metabolome. The focus of this review is on proteomic biomarkers associated with PAD.

Impact of clinical and subclinical peripheral arterial disease in mid-term prognosis of patients with acute coronary syndrome

Observational studies report poor prognosis of patients after acute coronary syndrome (ACS) in the presence of previous peripheral arterial disease (PAD), but data on subclinical PAD are scarce. This study was designed to assess the predictive value of clinical and subclinical PAD in the follow-up of patients after an ACS. We included 1,054 patients hospitalized for an ACS who survived the acute phase. Patients were divided into 3 groups: clinical PAD (previously diagnosed PAD or intermittent claudication), subclinical PAD (defined as ankle-brachial index <or=0.9 or >1.4), and no PAD. Clinical PAD was present in 150 patients (14.2%) and 298 cases of subclinical PAD were detected (28.3%). Patients with PAD (clinical and subclinical PAD) were significantly older and had a higher prevalence of hypertension and diabetes mellitus than those without PAD. During the 1-year follow-up, 59 patients died (5.6%). Previous PAD (hazard ratio 4.38, 95% confidence interval 1.96 to 9.82, p <0.001) and subclinical PAD (hazard ratio 2.35, 95% confidence interval 1.05 to 5.23, p <0.05) were associated with increased cardiovascular mortality. Moreover, patients with clinical PAD had higher rates of major cardiovascular events (myocardial infarction, angina, and heart failure) than patients with subclinical PAD or without PAD. In conclusion, beyond clinical PAD, measurement of ankle-brachial index after ACS provides substantial information on intermediate-term prognosis.