Dyslipidemia Profiles in Patients with 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.

Mechanical, structural, and physiologic differences between above and below-knee human arteries

Peripheral Artery Disease (PAD) affects the lower extremities and frequently results in poor clinical outcomes, especially in the vessels below the knee. Understanding the biomechanical and structural characteristics of these arteries is important for improving treatment efficacy, but mechanical and structural data on tibial vessels remain limited. We compared the superficial femoral (SFA) and popliteal (PA) arteries that comprise the above-knee femoropopliteal (FPA) segment to the infrapopliteal (IPA) anterior tibial (AT), posterior tibial (PT), and fibular (FA) arteries from the same 15 human subjects (average age 52, range 42-67 years, 87 % male). Vessels were imaged using μCT, evaluated with biaxial mechanical testing and constitutive modeling, and assessed for elastin, collagen, smooth muscle cells (SMCs), and glycosaminoglycans (GAGs). IPAs were more often diseased or calcified compared to the FPAs. They were also twice smaller, 53 % thinner, and significantly stiffer than the FPA longitudinally, but not circumferentially. IPAs experienced 48 % higher physiologic longitudinal stresses (62 kPa) but 27 % lower circumferential stresses (24 kPa) and similar cardiac cycle stretch of <1.02 compared to the FPA. IPAs had lower longitudinal pre-stretch (1.12) than the FPAs (1.29), but there were no differences in the stored elastic energy during pulsation. The physiologic circumferential stiffness was similar in the above and below-knee arteries (718 kPa vs 754 kPa). Structurally, IPAs had less elastin, collagen, and GAGs than the FPA, but maintained similar SMC content. Our findings contribute to a better understanding of segment-specific human lower extremity artery biomechanics and may inform the development of better medical devices for PAD treatment. STATEMENT OF SIGNIFICANCE: Peripheral Artery Disease (PAD) in the lower extremity arteries exhibits distinct characteristics and results in different clinical outcomes when treating arteries above and below the knee. However, their mechanical, structural, and physiologic differences are poorly understood. Our study compared above- and below-knee arteries from the same middle-aged human subjects and demonstrated distinct differences in size, structure, and mechanical properties, leading to variations in their physiological behavior. These insights could pave the way for creating location-specific medical devices and treatments for PAD, offering a more effective approach to its management. Our findings provide new, important perspectives for clinicians, researchers, and medical device developers interested in treating PAD in both above- and below-knee locations.

Prevalence of Peripheral Arterial Disease in Diabetic Foot Ulcer Patients and its Impact in Limb Salvage

Diabetic foot ulcer syndrome is a common complication of diabetes mellitus. Three main factors contribute to it: neuropathy, vasculopathy, and infection. This study was conducted to evaluate the prevalence of peripheral arterial disease (PAD) in diabetic foot ulcer patients and its impact on limb salvage as an outcome. This prospective cross-sectional study included 392 cases, who were divided according to the presence of PAD into 2 groups; patients with PAD were labeled as PAD +ve (172 cases) and those without PAD were labeled as PAD -ve (22 cases). All cases were clinically assessed, and routine laboratory examinations were ordered. Moreover, duplex ultrasound was done for suspected cases of having PAD by examination. Computed tomography angiography was ordered for patients who are in need of a revascularization procedure. Cases were managed by debridement and/or revascularization. After that, these cases were assessed clinically and radiologically for vascularity and infection and the possibility for amputation was evaluated. Infection was classified using Wagner Classification System, and revascularization was decided according to the TASC II system. The incidence of PAD in cases with diabetic foot ulcer syndrome was 43.87%. No difference was detected between the 2 groups regarding age and gender (P > .05). The prevalence of smoking, hemodialysis, ischemic heart disease (IHD), and hypertension was more significantly higher in cases with PAD (P < .05). Revascularization procedures were only performed in cases that had documented severe PAD or chronic limb-threatening ischemia in addition to foot ulcer and/or infection. With regard to limb salvage, it was more significantly performed in cases without PAD (82.3% vs 48.3% in PAD cases; P < .001). Male gender, smoking, ankle-brachial pressure index, hemodialysis, IHD, neuropathy, HbA1C, PAD, and high Wagner classification were predictors of limb amputation (P < .05). PAD is associated with worse outcomes in diabetic foot ulcer patients. Not only does it constitute a great number among diabetic foot ulcer patients, but it also has a negative impact on limb salvage.

Integrative metabolomics differentiate coronary artery disease, peripheral artery disease, and venous thromboembolism risks

Rationale

Arterial and venous cardiovascular conditions, such as coronary artery disease (CAD), peripheral artery disease (PAD), and venous thromboembolism (VTE), are genetically correlated. Interrogating distinct and overlapping mechanisms may shed new light on disease mechanisms.

Objective

In this study, we aimed to: identify and compare (1) epidemiologic and (2) causal, genetic relationships between metabolites and CAD, PAD, and VTE.

Methods

We used metabolomic data from 95,402 individuals in the UK Biobank, excluding individuals with prevalent cardiovascular disease. Logistic regression models adjusted for age, sex, genotyping array, first five principal components of ancestry, and statin use estimated the epidemiologic associations of 249 metabolites with incident CAD, PAD, or VTE. Bidirectional two-sample Mendelian randomization (MR) estimated the causal effects between metabolites and cardiovascular phenotypes using genome-wide association summary statistics for metabolites (N = 118,466 from UK Biobank), CAD (N = 184,305 from CARDIoGRAMplusC4D 2015), PAD (N = 243,060 from Million Veterans Project) and VTE (N = 650,119 from Million Veterans Project). Multivariable MR (MVMR) was performed in subsequent analyses.

Results

We found that 194, 111, and 69 metabolites were epidemiologically associated (P < 0.001) with CAD, PAD, and VTE, respectively. Metabolomic profiles exhibited variable similarity between disease pairs: CAD and PAD (N = 100 shared associations, R2 = 0.499), CAD and VTE (N = 68, R2 = 0.455), and PAD and VTE (N = 54, R2 = 0.752). MR revealed 28 metabolites that increased risk for both CAD and PAD and 2 metabolites that increased risk for CAD but decreased risk for VTE. Despite strong epidemiologic overlap, no metabolites had a shared genetic relationship between PAD and VTE. MVMR revealed several metabolites with shared causal effects on CAD and PAD related to cholesterol content within very-low-density lipoprotein particles.

Conclusions

While common arterial and venous conditions are associated with overlapping metabolomic profiles, MR prioritized the role of remnant cholesterol in arterial diseases but not venous thrombosis.

Acute Coronary Syndrome: Disparities of Pathophysiology and Mortality with and without Peripheral Artery Disease

There are a number of devastating complications associated with peripheral artery disease, including limb amputations and acute limb ischemia. Despite the overlap, atherosclerotic diseases have distinct causes that need to be differentiated and managed appropriately. In coronary atherosclerosis, thrombosis is often precipitated by rupture or erosion of fibrous caps around atheromatous plaques, which leads to acute coronary syndrome. Regardless of the extent of atherosclerosis, peripheral artery disease manifests itself as thrombosis. Two-thirds of patients with acute limb ischemia have thrombi associated with insignificant atherosclerosis. A local thrombogenic or remotely embolic basis of critical limb ischemia may be explained by obliterative thrombi in peripheral arteries of patients without coronary artery-like lesions. Studies showed that thrombosis of the above-knee arteries was more commonly due to calcified nodules, which are the least common cause of luminal thrombosis associated with acute coronary events in patients with acute coronary syndrome. Cardiovascular mortality was higher in peripheral artery disease without myocardial infarction/stroke than in myocardial infarction/stroke without peripheral artery disease. The aim of this paper is to gather published data regarding the disparities of acute coronary syndrome with and without peripheral artery disease in terms of pathophysiology and mortality.

Monitoring Muscle Perfusion in Rodents During Short-Term Ischemia Using Power Doppler Ultrasound

OBJECTIVE

The aim of this work was to evaluate the reliability of power Doppler ultrasound (PD-US) measurements made without contrast enhancement to monitor temporal changes in peripheral blood perfusion.

METHODS

On the basis of pre-clinical rodent studies, we found that combinations of spatial registration and clutter filtering techniques applied to PD-US signals reproducibly tracked blood perfusion in skeletal muscle. Perfusion is monitored while modulating hindlimb blood flow. First, in invasive studies, PD-US measurements in deep muscle with laser speckle contrast imaging (LSCI) of superficial tissues made before, during and after short-term arterial clamping were compared. Then, in non-invasive studies, a pressure cuff was employed to generate longer-duration hindlimb ischemia. Here, B-mode imaging was also applied to measure flow-mediated dilation of the femoral artery while, simultaneously, PD-US was used to monitor downstream muscle perfusion to quantify reactive hyperemia. Measurements in adult male and female mice and rats, some with exercise conditioning, were included to explore biological variables.

RESULTS

PD-US methods are validated through comparisons with LSCI measurements. As expected, no significant differences were found between sexes or fitness levels in flow-mediated dilation or reactive hyperemia estimates, although post-ischemic perfusion was enhanced with exercise conditioning, suggesting there could be differences between the hyperemic responses of conduit and resistive vessels.

CONCLUSION

Overall, we found non-contrast PD-US imaging can reliably monitor relative spatiotemporal changes in muscle perfusion. This study supports the development of PD-US methods for monitoring perfusion changes in patients at risk for peripheral artery disease.

Medical Management of Peripheral Artery Disease

Peripheral artery disease (PAD) is a common type of atherosclerotic disease of the lower extremities associated with reduced quality of life and ambulatory capacity. Major adverse cardiovascular events and limb amputations are the leading cause of morbidity and mortality in this population. Optimal medical therapy is therefore critical in these patients to prevent adverse events. Risk factor modifications, including blood pressure control and smoking cessation, in addition to antithrombotic agents, peripheral vasodilators, and supervised exercise therapy are key pillars of medical therapy. Revascularization procedures represent key touch points between patients and health care providers and serve as opportunities to optimize medical therapy and improve long-term patency rates and outcomes. This review summarizes the aspects of medical therapy that all providers should be familiar with when caring for patients with PAD in the peri-revascularization period.

Prevalence and predictors of lower extremity atherosclerotic disease amongst high-risk patients using ankle brachial index

INTRODUCTION

The prevalence of lower extremity artery disease (LEAD) continues to increase worldwide. This is expected to translate into logarithmic rise in lower-limb amputations especially in the developing world. Majority of patients suffering from LEAD remain asymptomatic until late and are vulnerable to limb-threatening complications unless actively screened and treated.

METHODS

This was a prospective, single-center, observational study to determine the prevalence and predictors of LEAD. Patients with known atherosclerotic vascular disease (but not known LEAD) or those at risk were enrolled. All underwent ABI measurement as per the standard protocol. A threshold of ABI ≤ 0.90 was taken to diagnose LEAD.

RESULTS

A total of 1000 patients were enrolled. The mean age of the group was 61.4±10.0 years and the prevalence of LEAD was 10.2%. Amongst those who had LEAD, the majority of patients (69.6%) had no symptoms. The prevalence of LEAD in diabetic population in our study was 13.2% and in coronary artery disease patients it was 30.9%. Factors independently linked to LEAD on regression analysis included advanced age, presence of diabetes, smoking history, lower serum HDL and a lower ejection fraction.

CONCLUSIONS

The vast majority of patients suffering from LEAD are asymptomatic. Early diagnoses and institution of appropriate medical and physical therapy can prevent excess morbidity and mortality due to LEAD. Factors independently linked to LEAD are advanced age, presence of diabetes, smoking history, lower serum HDL and a lower ejection fraction. The presence of either of these should signal undertaking of appropriate steps to unmask underlying LEAD.

Virgin Coconut Oil: A Dietary Intervention for Dyslipidaemia in Patients with Diabetes Mellitus

Hyperlipidaemia is causally related to coronary artery diseases (CAD) and peripheral artery diseases (PAD) in people with Diabetes Mellitus (DM). An in vivo study confirmed that virgin coconut oil (VCO) could maintain levels of lipids in the blood as effectively as conventional therapy. Therefore, this study aimed to determine the effect of VCO on the lipid profiles and ankle-brachial index (ABI) of patients with DM. In this experimental study with pre- and post-test design and a control group, the participants were selected purposively. The ABI was evaluated on the first visit. Baseline lipid profile readings were taken. Each participant took 1.2 mL/kgBW of VCO daily and divided it into three doses. After 30 days of taking VCO, laboratory examinations and ABI were repeated, and adverse events were evaluated. The dependent t-test and Wilcoxon sign rank test with a significance level of α ≤ 0.05 showed a significant decrease in low-density lipoprotein (LDL) (p = 0.002), a significant increase in high-density lipoprotein (HDL) levels (p = 0.031), a significant decrease in energy intake (p = 0.046) and cholesterol intake (p = 0.023) at the endpoint in the VCO group. In conclusion, this therapy is beneficial for maintaining lipid profile when combined with dietary therapy. Future studies should investigate the duration and dosage of VCO on patients to maintain lipid-linked protein.

Quantifying leg muscle deoxygenation during incremental cycling in hypoxemic patients with fibrotic interstitial lung disease

BACKGROUND

Hypoxaemia and cardiocirculatory abnormalities may impair muscle oxygen (O₂ ) delivery relative to O₂ requirements thereby increasing the rate of O₂ extraction during incremental exercise in fibrotic interstitial lung disease (f-ILD). Using changes in deoxyhaemoglobin concentration ([HHb]) by near-infrared spectroscopy (NIRS) as a proxy of O₂ extraction, we investigated whether a simplified (double-linear) approach, previously tested in heart failure, would provide useful estimates of muscle deoxygenation in f-ILD.

METHODS

A total of 25 patients (23 men, 72 ± 8 years; 20 with idiopathic pulmonary fibrosis, lung diffusing capacity for carbon monoxide = 44 ± 11% predicted) and 12 age- and sex-matched healthy controls performed incremental cycling to symptom limitation. Changes in vastus lateralis [HHb] assessed by NIRS were analysed in relation to work rate (WR) and O₂ uptake throughout the exercise.

RESULTS

Patients showed lower exercise capacity than controls (e.g., peak WR = 67 ± 18% vs. 105 ± 20% predicted, respectively; p < 0.001). The [HHb] response profile was typically S-shaped, presenting three distinct phases. Exacerbated muscle deoxygenation in patients versus controls was evidenced by: (i) a steeper mid-exercise [HHb]-WR slope (0.30 ± 0.22 vs. 0.11 ± 0.08 μmol/W; p = 0.008) (Phase 2), and (ii) a larger late-exercise increase in [HHb] (p = 0.002) (Phase 3). Steeper [HHb]-WR slope was associated with lower peak WR (r = -0.70) and greater leg discomfort (r = 0.77; p < 0.001) in f-ILD.

CONCLUSION

This practical approach to interpreting [HHb] during incremental exercise might prove useful to determine the severity of muscle deoxygenation and the potential effects of interventions thereof in hypoxemic patients with f-ILD.

Genetic evidence for a causal relationship between type 2 diabetes and peripheral artery disease in both Europeans and East Asians

BACKGROUND

Observational studies have revealed that type 2 diabetes (T2D) is associated with an increased risk of peripheral artery disease (PAD). However, whether the two diseases share a genetic basis and whether the relationship is causal remain unclear. It is also unclear as to whether these relationships differ between ethnic groups.

METHODS

By leveraging large-scale genome-wide association study (GWAS) summary statistics of T2D (European-based: N_case = 21,926, N_control = 342,747; East Asian-based: N_case = 36,614, N_control = 155,150) and PAD (European-based: N_case = 5673, N_control = 359,551; East Asian-based: N_case = 3593, N_control = 208,860), we explored the genetic correlation and putative causal relationship between T2D and PAD in both Europeans and East Asians using linkage disequilibrium score regression and seven Mendelian randomization (MR) models. We also performed multi-trait analysis of GWAS and two gene-based analyses to reveal candidate variants and risk genes involved in the shared genetic basis between T2D and PAD.

RESULTS

We observed a strong genetic correlation (r_g) between T2D and PAD in both Europeans (r_g = 0.51; p-value = 9.34 × 10^-15) and East Asians (r_g = 0.46; p-value = 1.67 × 10^-12). The MR analyses provided consistent evidence for a causal effect of T2D on PAD in both ethnicities (odds ratio [OR] = 1.05 to 1.28 for Europeans and 1.15 to 1.27 for East Asians) but not PAD on T2D. This putative causal effect was not influenced by total cholesterol, body mass index, systolic blood pressure, or smoking initiation according to multivariable MR analysis, and the genetic overlap between T2D and PAD was further explored employing an independent European sample through polygenic risk score regression. Multi-trait analysis of GWAS revealed two novel European-specific single nucleotide polymorphisms (rs927742 and rs1734409) associated with the shared genetic basis of T2D and PAD. Gene-based analyses consistently identified one gene ANKFY1 and gene-gene interactions (e.g., STARD10 [European-specific] to AP3S2 [East Asian-specific]; KCNJ11 [European-specific] to KCNQ1 [East Asian-specific]) associated with the trans-ethnic genetic overlap between T2D and PAD, reflecting a common genetic basis for the co-occurrence of T2D and PAD in both Europeans and East Asians.

CONCLUSIONS

Our study provides the first evidence for a genetically causal effect of T2D on PAD in both Europeans and East Asians. Several candidate variants and risk genes were identified as being associated with this genetic overlap. Our findings emphasize the importance of monitoring PAD status in T2D patients and suggest new genetic biomarkers for screening PAD risk among patients with T2D.

Association of Gut Microbiota with Atherogenic Dyslipidemia, and Its Impact on Serum Lipid Levels after Bariatric Surgery

Gut microbiota has been suggested to modulate circulating lipids. However, the relationship between the gut microbiota and atherogenic dyslipidemia (AD), defined as the presence of both low HDL-C and hypertriglyceridemia, is not fully understood. Moreover, because obesity is among the main causes of secondary AD, it is important to analyze the effect of gut microbiota composition on lipid profiles after a weight loss intervention. We compared the microbial diversity and taxonomic composition in patients with AD (n = 41) and controls (n = 38) and sought correlations of genera abundance with serum lipid levels in 20 patients after weight loss induced by Roux-en-Y gastric bypass (RYGB) surgery. Gut microbiota composition was profiled using next-generation sequencing of 16S rRNA. Gut microbiota diversity was significantly lower in atherogenic dyslipidemia. Moreover, relative abundance of two genera with LDA score >3.5 (Megasphaera and LPS-producing Escherichia-Shigella), was significantly higher in AD subjects, while the abundance of four short chain fatty acids (SCFA) producing-genera (Christensenellaceae R-7, Ruminococcaceae UCG-014; Akkermansia and [Eubacterium] eligens group) was significantly higher in controls. Notably, [Eubacterium] eligens group abundance was also significantly associated with higher HDL-C levels in RYGB patients one year after surgery. Although dietary polyunsaturated fatty acid/saturated fatty acid (PUFA/SFA) ratio and PUFA intake were higher in controls than in AD subjects, of the four genera differentiated in cases and controls, only Akkermansia abundance showed a positive and significant correlation with PUFA/SFA ratio. Our results suggest that SCFA-producing bacteria promote a healthy lipid homeostasis, while the presence of LPS-producing bacteria such Escherichia-Shigella may contribute to the development of atherogenic dyslipidemia.

Risk of peripheral artery occlusive disease in patients with lower leg fracture who received fixation and non-fixation treatments: A population cohort study

Background

The risk of peripheral artery occlusive disease (PAOD) in patients with lower leg fracture who underwent fixation procedures is not yet completely understood. Therefore, the current study aimed to examine the risk of subsequent PAOD in patients with lower leg fracture who received fixation and non-fixation treatments.

Methods

We included 6538 patients with lower leg fracture who received non-fixation treatment and a matched cohort comprising 26152 patients who received fixation treatment from the National Health Insurance Database. Patients were frequency matched according to age, sex, and index year. The incidence and risk of PAOD in patients with lower leg fracture who received fixation and non-fixation treatments were evaluated via the stratification of different characteristics and comorbidities.

Results

Non-fixation treatment, male sex, older age (≥ 50 years old), diabetes mellitus, and gout were associated with a significantly higher risk of lower extremity PAOD compare to each comparison group, respectively. Moreover, there was a significant correlation between fixation treatment and a lower risk of lower extremity PAOD in women (adjusted hazard ratio [aHR] = 0.58, 95% confidence interval [CI] = 0.38–0.90), women aged > 50 years (aHR = 0.61, 95% CI = 0.38–0.96), and patients with coronary artery disease (aHR = 0.43, 95% CI = (0.23–0.81). Further, patients with fixation treatment had a significantly lower risk of lower extremity PAOD within 2 years after trauma (aHR = 0.57, 95% CI = 0.34–0.97). The Kaplan–Meier analysis showed that the cumulative incidence of PAOD was significantly higher in the non-fixation treatment group than in the fixation treatment group at the end of the 10-year follow-up period (log-rank test: P = 0.022).

Conclusion

Patients with lower leg fracture who received non-fixation treatment had a significantly higher risk of PAOD than those who received fixation treatment. Moreover, the risk of PAOD was higher in women aged > 50 years, as well as in coronary artery disease patients who received non-fixation treatment than in those who received fixation treatment. Therefore, regular assessment of vessel patency are recommended for these patients. Nevertheless, further studies must be conducted to validate the results of our study.

Grain-Based Dietary Background Impairs Restoration of Blood Flow and Skeletal Muscle During Hindlimb Ischemia in Comparison With Low-Fat and High-Fat Diets

Background: Among vascular pathologies associated with obesity, peripheral artery disease (PAD) occupies the important position. In clinical practice, nutritional interventions are recommended for patients with PAD. In this work, we investigated how the different dietary backgrounds affect the regeneration rate of ischemic hindlimb in mice.

Methods: Male C57BL/6J mice were housed on three types of diet: low-fat (LFD), high-fat (HFD), and grain-based diet (GBD) for 13 weeks. Metabolic parameters including FBG level, ITT, and GTT were evaluated. The blood flow was assessed by laser Doppler scanning on 7, 14, and 21 days after hindlimb ischemia. Necrotic area of m.tibialis, macrophage infiltration, and angiogenesis/arteriogenesis were evaluated by histology. Glucose uptake in recovered skeletal muscle was analyzed using [3H]-2-deoxyglucose, and GLUT1 and GLUT4 expression were assessed by Western blotting.

Results: In our work, we developed three experimental groups with different metabolic parameters: LFD with normal glucose metabolism, GBD with mild hyperglycemia, and HFD with impaired glucose tolerance. GBD-fed mice had a tendency to increase necrosis of m. tibialis and significantly higher macrophage infiltration than LFD and HFD groups. Moreover, GBD-fed mice had a trend to decreased blood flow recovery and significantly impaired arteriogenesis. Recovered skeletal muscle of GBD-fed mice had lower glucose uptake and decreased level of GLUT4 expression.

Conclusion: Thus, we conclude that dietary background and metabolic status determine the rate of post-ischemic regeneration including angiogenesis, skeletal muscle recovery and metabolic activity. The most effective regeneration is supported by LFD, while the lowest rate of regeneration occurs on GBD.

Lipid profiles of patients with manifest coronary versus peripheral atherosclerosis - Is there a difference?

AIM

Peripheral arterial disease (PAD) and coronary artery disease (CAD) are both caused by atherosclerosis. Serum lipids and lipoproteins are predictive of the development of atherosclerosis but it is not clear if they differ in the two manifestations, PAD and CAD. We tested whether a more detailed characterization of the lipid and lipoprotein patterns of PAD and CAD allows a clear differentiation between the two atherosclerotic phenotypes.

METHODS

A cohort of 274 statin-naïve patients with either newly diagnosed imaging proven PAD (n = 89) or stable CAD (n = 185) was characterized using nuclear magnetic resonance- and liquid chromatography-tandem mass spectrometry-based advanced lipid and lipoprotein analysis. An independent cohort of 1239 patients with PAD and CAD was used for validation.

RESULTS

We found a significant difference in markers of inflammation as well as ceramide and phosphatidylcholine levels between patients with PAD and CAD. In contrast, basic lipid markers including total cholesterol, LDL cholesterol, HDL cholesterol, lipoprotein(a) or detailed lipoprotein profiles did not differ significantly between patients with PAD and CAD. Applying ratios and scores derived from ceramides and phosphatidylcholines further improved the discrimination between PAD and CAD. These significant differences were independent of body composition, from the status of smoking or type 2 diabetes mellitus, and also from apolipoprotein C-III and other inflammatory parameters which were different between CAD and PAD.

CONCLUSION

The present study clearly suggests that PAD and CAD differ in terms of their ceramide- and phosphatidylcholine-based lipid patterns but not in lipoprotein characteristics.

Medical Management of Peripheral Artery Disease

Peripheral artery disease is a highly morbid yet undertreated atherosclerotic disease. The cornerstones of peripheral artery disease therapy consist of smoking cessation, lipid-lowering therapy, and hypertension treatment. More recently, clinical trials have demonstrated that novel antiplatelet and antithrombotic therapies reduce the risk of both cardiovascular and limb events in this patient population. In this review, we highlight the components of optimal medical therapy of peripheral artery disease and the evidence base for these therapies.

Association Between Cumulative Exposure to Increased Low-Density Lipoprotein Cholesterol and the New Occurrence of Peripheral Artery Disease

Background and Purpose: Peripheral artery disease (PAD) is a manifestation of systemic atherosclerosis with increased risk of severe cardiovascular and cerebrovascular events. The relationship between one-time measuring of low-density lipoprotein cholesterol (LDL-C) and PAD is inconsistent. Increasing evidence shows that the predictive value of non-high-density lipoprotein cholesterol (non-HDLC) on atherosclerosis disease is superior to LDL-C. We aimed to investigate the relationship between cumulative exposure to increased LDL-C and the risk of newly developed PAD and compare the predictive value of LDL-C with non-HDLC. Materials and Methods: In the Asymptomatic Polyvascular Abnormalities Community study, we enrolled 2,923 participants with LDL-C and non-HDLC measured every 2 years from 2006 to 2012. Cumulative exposure to increased LDL-C and non-HDLC, defined as LDL-C burden and non-HDLC burden, respectively, was calculated as the weighted sum of the difference between the measured value and the cutoff value. A new occurrence of PAD was identified through ankle brachial index measured in 2010 and 2012. Multivariate models were adopted to analyze the association of LDL-C burden and non-HDLC burden with the newly developed PAD. The receiver operating curve was drawn, and the area under the curve was calculated to compare the predictive performance of LDL-C burden with a single measure of LDL-C in 2006 and non-HDL-C burden adjusted with a model including traditional risk factors. Results: Of the 2,923 participants, 5.4% (158/2,923) were diagnosed as newly developed PAD. In the univariate analysis, the highest quartile of LDL-C burden was significantly associated with new occurrence of PAD [odds ratio (OR) 1.75, 95% confidence interval (CI) 1.13-2.73]. After adjustment for confounding factors, the same result was obtained (OR 1.59, 95%CI 1.01-2.49). The non-HDLC burden failed to show any statistical significance on the newly developed PAD (OR 1.31, 95% CI 0.84-2.04). Though LDL-C burden had a tendency to show better predictive performance than non-HDLC, it did not reach statistical significance (AUCLDL-C = 0.554 vs. AUCnon-HDLC = 0.544, P = 0.655). Conclusions: Cumulative exposure to increased LDL-C is an independent risk factor of newly developed PAD. The predictive value of non-HDLC burden was not revealed.

Assessment of Serum Neopterin as a Biomarker in Peripheral Artery Disease

Neopterin (NPT), a pyrazino-pyrimidine compound mainly produced by activated macrophages, has been regarded as a proinflammatory and proatherosclerotic agent. The study was designed to evaluate NPT level and its interaction with conventional peripheral artery disease (PAD) biomarkers and vascular regenerative potential in severe PAD. The study included 59 patients (females n = 17, males n = 42) aged 67.0 ± 8.2 years classified into two groups based on ankle-brachial index (ABI) measurements (ABI ≤ 0.9 n = 43, ABI ≤ 0.5 n = 16). A total of 60 subjects aged 70.4 ± 5.5 years (females n = 42, males n = 18) with ABI > 0.9 constituted a reference group. NPT concentration reached values above 10 nmol/L in patients with PAD, which differed significantly from reference group (8.15 ± 1.33 nmol/L). High levels of CRP > 5 mg/L, TC > 200 mg/dL as well as lipoproteins LDL > 100 mg/dL and non-HDL > 130 mg/dL were found in the same group, indicating the relationship between NPT and conventional atherogenic markers. The endothelial progenitor cells (EPCs) tended toward lower values in patients with ABI ≤ 0.5 when compared to reference group, and inversely correlated with NPT. These findings indicate a crucial role of NPT in atheromatous process and its usefulness in monitoring PAD severity. However, the role of NPT in chronic PAD needs further studies including relatively high number of subjects.

Prioritizing the Role of Major Lipoproteins and Subfractions as Risk Factors for Peripheral Artery Disease

BACKGROUND

Lipoprotein-related traits have been consistently identified as risk factors for atherosclerotic cardiovascular disease, largely on the basis of studies of coronary artery disease (CAD). The relative contributions of specific lipoproteins to the risk of peripheral artery disease (PAD) have not been well defined. We leveraged large-scale genetic association data to investigate the effects of circulating lipoprotein-related traits on PAD risk.

METHODS

Genome-wide association study summary statistics for circulating lipoprotein-related traits were used in the mendelian randomization bayesian model averaging framework to prioritize the most likely causal major lipoprotein and subfraction risk factors for PAD and CAD. Mendelian randomization was used to estimate the effect of apolipoprotein B (ApoB) lowering on PAD risk using gene regions proxying lipid-lowering drug targets. Genes relevant to prioritized lipoprotein subfractions were identified with transcriptome-wide association studies.

RESULTS

ApoB was identified as the most likely causal lipoprotein-related risk factor for both PAD (marginal inclusion probability, 0.86; P=0.003) and CAD (marginal inclusion probability, 0.92; P=0.005). Genetic proxies for ApoB-lowering medications were associated with reduced risk of both PAD (odds ratio,0.87 per 1-SD decrease in ApoB [95% CI, 0.84-0.91]; P=9×10-10) and CAD (odds ratio,0.66 [95% CI, 0.63-0.69]; P=4×10-73), with a stronger predicted effect of ApoB lowering on CAD (ratio of effects, 3.09 [95% CI, 2.29-4.60]; P<1×10-6). Extra-small very-low-density lipoprotein particle concentration was identified as the most likely subfraction associated with PAD risk (marginal inclusion probability, 0.91; P=2.3×10-4), whereas large low-density lipoprotein particle concentration was the most likely subfraction associated with CAD risk (marginal inclusion probability, 0.95; P=0.011). Genes associated with extra-small very-low-density lipoprotein particle and large low-density lipoprotein particle concentration included canonical ApoB pathway components, although gene-specific effects were variable. Lipoprotein(a) was associated with increased risk of PAD independently of ApoB (odds ratio, 1.04 [95% CI, 1.03-1.04]; P=1.0×10-33).

CONCLUSIONS

ApoB was prioritized as the major lipoprotein fraction causally responsible for both PAD and CAD risk. However, ApoB-lowering drug targets and ApoB-containing lipoprotein subfractions had diverse associations with atherosclerotic cardiovascular disease, and distinct subfraction-associated genes suggest possible differences in the role of lipoproteins in the pathogenesis of PAD and CAD.

Bench-to-Bedside in Vascular Medicine: Optimizing the Translational Pipeline for Patients With Peripheral Artery Disease

Peripheral arterial disease is a growing worldwide problem with a wide spectrum of clinical severity and is projected to consume >$21 billion per year in the United States alone. While vascular researchers have brought several therapies to the clinic in recent years, few of these approaches have leveraged advances in high-throughput discovery screens, novel translational models, or innovative trial designs. In the following review, we discuss recent advances in unbiased genomics and broader omics technology platforms, along with preclinical vascular models designed to enhance our understanding of disease pathobiology and prioritize targets for additional investigation. Furthermore, we summarize novel approaches to clinical studies in subjects with claudication and ischemic ulceration, with an emphasis on streamlining and accelerating bench-to-bedside translation. By providing a framework designed to enhance each aspect of future clinical development programs, we hope to enrich the pipeline of therapies that may prevent loss of life and limb for those with peripheral arterial disease.

Apolipoprotein E Gene Polymorphism, Glycated Hemoglobin, and Peripheral Arterial Disease Risk in Chinese Type 2 Diabetic Patients

Background

The apolipoprotein E (ApoE) gene polymorphism has been found to influence plasma lipid concentration, and its correlation with peripheral arterial disease (PAD) has been investigated. However, it is unclear whether ApoE is associated with PAD in Chinese type 2 diabetes mellitus (T2DM) patients. Therefore, our study is aimed at investigating the relationship between the ApoE gene polymorphism and PAD in Chinese T2DM patients.

Methods

A total of 192 T2DM patients were divided into two groups: T2DM and T2DM with PAD. The clinical and biochemical parameters were obtained. Polymerase chain reaction was used to identify the genotypes of ApoE. The multivariable logistic regression analysis was used to identify the possible risk factor for PAD.

Results

There were no significant differences in the genotype and allele frequencies of ApoE between the T2DM and T2DM with PAD groups. However, the T2DM with PAD group tended to have more ε4/ε4/

Conclusions

These results demonstrated that there was no evidence of a relationship between ApoE and PAD.

Vitamin D Deficiency May Not Be an Independent Risk Factor for Peripheral Arterial Disease in Middle-Aged and Elderly Patients with Type 2 Diabetes in China

Background

Vitamin D deficiency can lead to the increased severity and prevalence of metabolic disorders. However, the relationship between levels of 25-hydroxyvitamin D (25(OH)D) and peripheral arterial disease (PAD) is controversial. Therefore, the purpose of our study was to explore the relationship between 25(OH)D levels and PAD in middle-aged and elderly type 2 diabetes mellitus (T2DM) patients in China.

Methods

In this study, a total of 183 patients with T2DM were enrolled and categorized into groups with or without PAD. Clinical and biochemical parameters were assessed, and a Pearson analysis was used to identify a possible association between levels of 25(OH)D and glycated hemoglobin (HbA1c). Some biochemical parameters were also assessed in the T2DM patients with PAD according to vitamin D status. Interactions were also explored among HbA1c control, 25(OH)D levels, and PAD. The possible risk factors for PAD were measured by multivariable logistic regression analyses.

Results

Firstly, the parameters including age, HbA1c, and disease duration between T2DM and T2DM+PAD groups showed significantly different. In addition, the frequency of smoking in the group of T2DM patients was significantly less than that in the T2DM patients with the PAD group, while the frequency of well-controlled HbA1c in the patients with T2DM was significantly higher. There is a trend that the levels of 25(OH)D and HbA1c are correlated, but no interactions among vitamin D deficiency, HbA1c control, and PAD were found. However, HbA1c significantly differed between groups with vitamin D deficiency and insufficiency in the T2DM patients with PAD. According to the multivariate logistic regression analyses, the PAD risk factors of T2DM patients were family history of diabetes, smoking, age, disease duration, HbA1c, and LDL.

Conclusions

The findings demonstrate that the deficiency of vitamin D level is not related to PAD, but HbA1c may be linked to the presence of PAD in middle-aged and elderly patients with T2DM in China.