Citations

Background and Purpose: XO (xanthine oxidase) is a key enzyme of uric acid metabolism and is thought to contribute to oxidative pathways that promote atherosclerotic plaque progression, yet its role in plaque destabilization is not well elucidated. We hypothesized that XO is expressed in carotid plaque from symptomatic patients in association with cardiovascular risk factors. Methods: Patients were stratified by symptoms, defined as presentation with an ipsilateral cerebral ischemic event. Carotid atherosclerotic plaques were obtained from 44 patients with symptomatic plaque and 44 patients without ischemic cerebral events. Protein expression of XO was evaluated by immunohistochemical staining and the percentage of cells expressing XO and CD68 (macrophage marker) compared between the groups. Biochemical and demographic cardiometabolic risk factors of study participants also were measured. Results: Carotid atherosclerotic plaques from symptomatic patients were associated with significantly higher XO expression versus asymptomatic plaque (median [interquartile range]: 1.24 [2.09] versus 0.16 [0.34]; P <0.001) and with significantly higher circulating uric acid levels (mean±SD: 7.36±2.10 versus 5.37±1.79 mg/dL; P <0.001, respectively). In addition, XO expression in atherosclerotic carotid plaque was inversely associated with serum high-density lipoproteins cholesterol levels ( P =0.010, r =−0.30) and directly with circulating uric acid levels ( P <0.001, r =0.45). The average percentage of macrophages that expressed XO was significantly higher in symptomatic versus asymptomatic plaques (median [interquartile range]: 93.37% [25] versus 46.15% [21], respectively; P <0.001). Conclusions: XO overexpression in macrophages is associated with increased serum uric acid and low high-density lipoproteins cholesterol levels and may potentially have a mechanistic role in carotid plaque destabilization. The current study supports a potential role for uric acid synthesis pathway as a target for management of carotid atherosclerosis in humans.

AbstractRegenerative, cell-based therapy is a promising treatment option for diabetic kidney disease (DKD), which has no cure. To prepare for clinical translation, this systematic review and meta-analysis summarized the effect of cell-based interventions in DKD animal models and treatment-related factors modifying outcomes. Electronic databases were searched for original investigations applying cell-based therapy in diabetic animals with kidney endpoints (January 1998-May 2019). Weighted or standardized mean differences were estimated for kidney outcomes and pooled using random-effects models. Subgroup analyses tested treatment-related factor effects for outcomes (creatinine, urea, urine protein, fibrosis, and inflammation). In 40 studies (992 diabetic rodents), therapy included mesenchymal stem/stromal cells (MSC; 61%), umbilical cord/amniotic fluid cells (UC/AF; 15%), non-MSC (15%), and cell-derived products (13%). Tissue sources included bone marrow (BM; 65%), UC/AF (15%), adipose (9%), and others (11%). Cell-based therapy significantly improved kidney function while reducing injury markers (proteinuria, histology, fibrosis, inflammation, apoptosis, epithelial-mesenchymal-transition, oxidative stress). Preconditioning, xenotransplantation, and disease-source approaches were effective. MSC and UC/AF cells had greater effect on kidney function while cell products improved fibrosis. BM and UC/AF tissue sources more effectively improved kidney function and proteinuria vs adipose or other tissues. Cell dose, frequency, and administration route also imparted different benefits. In conclusion, cell-based interventions in diabetic animals improved kidney function and reduced injury with treatment-related factors modifying these effects. These findings may aid in development of optimal repair strategies through selective use of cells/products, tissue sources, and dose administrations to allow for successful adaptation of this novel therapeutic in human DKD.

Background Resistive reserve ratio (RRR), or the ratio of baseline to hyperemic microvascular resistance, has prognostic implications in predicting clinical outcomes in patients with obstructive coronary artery disease. However, its value in patients with angina or ischemia with nonobstructive coronary artery disease is unknown. Methods and Results We included 1692 patients with nonobstructive coronary artery disease who underwent invasive coronary vasoreactivity testing. Abnormal coronary flow reserve (CFR, the ratio of hyperemic and baseline resting flow velocities) and RRR were defined as <2.5 and <2.62, respectively. The mortality rate was marginally higher in patients with abnormal CFR (428 patients [25%]) than those with normal CFR (38 [9%] versus 81 [6%]; P =0.08), and was significantly higher in patients with abnormal RRR (716 patients [42%]) than those with normal RRR (70 [10%] versus 49 [5%], P =0.0002) over the median follow‐up of 11.3 years. Patients with abnormal CFR had marginally lower survival than those with normal CFR (log‐rank P =0.08). In contrast, patients with abnormal RRR had significantly lower survival than those with normal RRR (log‐rank P =0.001). Abnormal RRR was associated with shorter time to death even after adjustment for other covariates (adjusted hazard ratio, 1.63; 95% CI, 1.11–2.38; P =0.01). Conclusions In patients with no obstructive coronary artery disease, RRR was superior to CFR in predicting long‐term survival. An RRR <2.62 was associated with 1.6 times increased risk of death in patients with nonobstructive coronary artery disease. Indices of coronary microcirculatory resistive reserve comprising flow‐ and pressure‐derived values may reflect underlying microvascular pathology more faithfully than flow‐alone indices like CFR.

Introduction: Previous studies in patients with Raynaud’s phenomenon (RP) have found an association between microvascular abnormalities assessed via nail fold capillaroscopy as well as macrovascular peripheral endothelial dysfunction (PED). However, the association between RP and microvascular PED is not yet established. Hypothesis: We hypothesized that patients with RP have greater microvascular PED compared to controls without RP Methods: We performed a retrospective cross-sectional analysis of patients referred to Mayo Clinic between 2006 and 2014 for routine cardiovascular evaluation, and who underwent evaluation of Reactive Hyperemia Peripheral Arterial Tonometry (index < 2 consistent with PED). Patients with RP were identified by chart review. Results: Six hundred sixty six individuals were included in this study (mean age 51.9±13.5 years, 411 (61.3%) women), 637 (95.1%) individuals did not have RP (control group), and 29 (4.3%) had secondary RP. Only 4 patients had primary RP and were excluded from the final analyses. Individuals with secondary RP had a higher frequency of microvascular PED compared to controls ( Figure ). In a multivariate analysis adjusting for age, sex, smoking status, and use of statins we found a significant association between secondary RP and microvascular PED (OR: 2.45; 95% CI 1.13-5.34; P=0.0236) that remained significant in women after stratifying by sex. In a sensitivity analysis, we compared the frequency of PED in 29 patients with secondary RP and 58 controls matched with respect to age, sex, hypertension, dyslipidemia, and diabetes mellitus. Individuals with secondary RP had a higher frequency of microvascular PED compared to the risk factor-matched controls (18/29 [62.1%] vs 18/58 [31.0%], P=0.01). Conclusions: Secondary RP is associated with microvascular PED. Early detection of microvascular PED could help identify individuals with secondary RP who are at risk for developing cardiovascular disease.

Introduction: Cardiac allograft vasculopathy (CAV) is a major determinant of long term graft survival. Endothelial progenitor cells (EPC) expressing osteocalcin (OC) have been linked to atherosclerosis. However, little is known regarding bone-forming osteoblast-lineage (OL) cells, and their role in atherosclerosis and CAV. Methods: Heart transplant patients undergoing serial Intravascular Ultrasound (IVUS) and progenitor cell studies were included in the study. OL cells, defined as cells positive for alkaline phosphatase (AP) and OC, were counted using flow cytometry on the day of baseline IVUS. A follow up IVUS was done 3 years later. Gray-scale and virtual-histology IVUS were used to evaluate vessel size, plaque burden, and plaque composition (fibrous, fibrofatty, necrotic core, calcified). Patients were divided into two groups by the median change (Δ) in necrotic core volume and plaque volume over 3 years. Results: A total of 55 patients (mean age 52±15 years, 65% males) were included. At baseline, median time after transplant was 4.2 years. Average vessel area at baseline and three years were 15.8 ±4.6 and 15.3 ±5.4 mm2, respectively (p=0.32). However, 24/55 patients (44%) had positive remodeling. The number of OL cells was positively correlated with Δvessel (r=0.36, p=0.01) and Δlumen areas. (r=0.30, p=0.02). Patients with greater Δplaque volume and Δnecrotic core volume had higher OL cell levels compared to those with below medians (Δplaque volume: 95 [30,348] vs. 30 [10, 90] OL per 100,000 counts, p=0.01; Δnecrotic core volume: 95 [22.5, 320] vs. 30 [10, 90] OL per 100,000 counts, p=0.03) (Fig. 1A and 1B). Conclusions: The number of OL cells in heart transplant patients correlates with positive vascular remodeling, accompanied by increased lumen area over 3 months. Furthermore, patients with unstable plaque features had higher OL cells, suggesting a possible role in pathologic plaque progression.

Introduction: CD34+ progenitor cells play a role in vascular repair and plaque stability. However, their role in cardiac allograft vasculopathy (CAV), vessel remodeling, and changes in plaque morphology is incompletely understood. Hypothesis: We hypothesized that decreased levels of baseline CD34+ progenitor cells would be associated with Intravascular Ultrasound (IVUS)-defined vulnerable plaque characteristics and CAV progression. Methods: In heart transplant patients undergoing annual IVUS, CD34+ cells were counted in peripheral blood using flow cytometry, on the same day as baseline IVUS. Gray-scale and virtual-histology IVUS were used to evaluate vessel size, plaque burden, and plaque composition (fibrous, fibrofatty, necrotic core, calcific). Positive remodeling was defined as expansion of external elastic membrane area on follow-up. Patients were divided into two groups by the median of the change (Δ) in necrotic core volume over the subsequent 3 years. Results: A total of 55 patients (mean age 52±15 years, 65% males) were included. Median time after transplant was 4.2 years at baseline. Average vessel area at baseline and three years were 15.8±4.6 and 15.3±5.4 mm, respectively (p=0.32). Twenty-four patients (44%) who showed positive remodeling at follow-up, compared to those who did not, had lower levels of baseline CD34+ progenitor cells (absolute count per 100,000 counts, 980 [690, 1460]) vs. 665 [438, 1015], p=0.02) (Fig. 1A). Patients with greater than median (>1.96 mm3) Δnecrotic core volume, as compared to those with below median Δ, also had lower baseline CD34+ cells (705 [483, 998] vs. 1180 [660, 1620] per 100,000 counts, p=0.04) (Fig. 1B). Conclusions: Lower levels of CD34+ progenitor cells are associated with long-term positive coronary vascular remodeling and increased plaque necrotic core volume in patients who underwent allograft heart transplant. This study supports the notion that circulating CD34+ progenitor cells play a role in CAV.

Introduction: Coronary microvascular dysfunction (CMD) is prevalent in symptomatic patients with no obstructive coronary artery disease. We postulated that exercise capacity and cardiac output augmentation in response to exercise are linked to coronary microvascular function in this patient population. Methods: Fifty-one consecutive patients with unexplained cardiac exertion symptoms, non-obstructive coronary artery disease on angiography (<50% stenosis), and normal left ventricular ejection fraction (>50%) who underwent concurrent clinically indicated coronary reactivity testing and invasive cardiopulmonary exercise testing (CPEX) were included. Microvascular function was assessed by coronary flow reserve (CFR; hyperemic/resting flow) in response to intracoronary adenosine injection. Cardiac output (CO) was calculated at rest and peak exercise using Fick’s formula. CO limitation was defined as a measured (peak CO - resting CO) <80% than the expected [6*absolute ΔVO 2 (Peak VO 2 -Rest VO 2 ) increase in CO in L/min]. The relationship between CFR, maximal exercise capacity, and CO augmentation at peak exercise was explored. Results: Patients were 56.6±10.5 years old and 73% were females. CFR had a modest positive correlation with measured increase in CO (r=0.42; P=0.003) ( Fig 1A ), and with maximal ergometric exercise capacity [in Watts/Kg] (Pearson’s r=0.33, P=0.02) ( Fig 1B ). Patients with, vs. without impaired cardiac limitations during exercise, had significantly lower CFR levels (2.6±0.5 vs 3.1±0.7; P=0.01) ( Fig 2 ). Conclusion: Impaired coronary microvascular function is associated with lower peak exercise capacity and reduced cardiac output augmentation in response to exercise, underscoring the functional ramification of CMD in symptomatic patients.

Title: Serum NT-proB-type Natriuretic Peptide is associated with Coronary Microvascular Dysfunction in Patients with Angina and Non-obstructive Coronary Artery Disease Authors: Ali Ahmad, MD, Jaskanwal D. Sara, MBChB, Michel T. Corban, MD, Takumi Toya, MD, Ilke Özcan, MD, Lilach O. Lerman, MD PhD, Amir Lerman, MD Introduction: Coronary microvascular dysfunction (CMD) is prevalent in patients with heart failure with preserved ejection fraction. Subclinical ischemia and myocardial fibrosis in CMD might raise filling pressure, a hallmark of HFpEF, which induces secretion of NT-proB-type natriuretic peptide (NTpro-BNP). We sought to explore the relationship between CMD and NT-proBNP. Methods: We studied 698 patients with signs and/or symptoms of ischemia and with non-obstructive CAD (<40% angiographic stenosis) who underwent invasive CMD evaluation and had NT-proBNP checked within 6 weeks. CMD was defined as coronary flow reserve (CFR) (hyperemic flow/baseline flow as measured by the doppler wire) of ≤2.5 in response to intracoronary adenosine injection. Results: Overall mean age was 52.8±12.2 years, and women represented 69% of the patients. Log NT-proBNP showed a modest inverse correlation with CFR (Pearson’s R = -0.22, P<0.0001; Figure 1 ), which remained significant after adjusting for age and gender (Standardized ß coefficient = -0.14; P = 0.001). Patients with CMD had higher levels of NT-proBNP than those without (82 [44-190] vs. 62 (33-130], P <0.0001; Figure 2) . Conclusion: Declining coronary microvascular function is correlated with higher NT-proBNP levels. Patients with CMD had higher levels of NT-proBNP, a marker of elevated LV pressure, contributing to the possible role of CMD in early HFpEF pathophysiology. Keywords: Coronary microvascular dysfunction, NT-proBNP

Introduction: Subjects with renovascular hypertension (RVH) often manifest with metabolic syndrome (MetS), increasing risk for heart failure, yet the mechanisms underlying cardiac injury remain unknown. Reduced mitophagy and accumulation of impaired mitochondria have been linked to progression of heart failure. Hypothesis: We hypothesized that superimposition of MetS on RVH in swine inhibits myocardial mitophagy, aggravating mitochondrial damage, cardiac injury and dysfunction. Methods: Pigs were studied after 16 weeks of RVH (renal artery stenosis) with or without diet-induced MetS, and Lean controls (n=6 each). Cardiac function was assessed in vivo (multidetector-CT), and cardiac mitochondrial structure, function, mitophagy, and myocardial fibrosis ex vivo. Results: MetS groups developed obesity, whereas RVH groups developed hypertension (Table). Mitochondrial matrix density and ATP production were lower and H2O2 production higher in both RVH groups vs. Lean and MetS (Fig. AB). However, MetS+RVH failed to activate mitophagy and downregulate myocardial expression of mitophagy-related microRNAs achieved by Lean+RVH (Fig. CD). Myocardial expression of the mitophagy marker PTEN-induced kinase (PINK)-1 inversely correlated with myocardial fibrosis (R 2 =0.195, p=0.031). Cardiac fibrosis, hypertrophy, and diastolic dysfunction (decreased E/A ratio) were greater in MetS+RVH vs. Lean+RVH (Table, Fig. E). Conclusions: MetS aggravates myocardial mitochondrial damage and dysfunction in swine RVH. MetS+RVH failed to activate mitophagy, resulting in greater cardiac remodeling, fibrosis, and diastolic dysfunction. Mitochondrial injury and impaired mitophagy may constitute important mechanisms and potential therapeutic targets to ameliorate cardiac structural damage and dysfunction in patients with coexisting MetS and RVH.

Mesenchymal stem/stromal cells (MSCs) facilitate repair in experimental diabetic kidney disease (DKD). However, the hyperglycemic and uremic milieu may diminish regenerative capacity of patient-derived therapy. We hypothesized that DKD reduces human MSC paracrine function. Adipose-derived MSC from 38 participants with DKD and 16 control subjects were assessed for cell surface markers, trilineage differentiation, RNA sequencing (RNA-seq), in vitro function (coculture or conditioned medium experiments with T cells and human kidney cells [HK-2]), secretome profile, and cellular senescence abundance. The direction of association between MSC function and patient characteristics were also tested. RNA-seq analysis identified 353 differentially expressed genes and downregulation of several immunomodulatory genes/pathways in DKD-MSC versus Control-MSC. DKD-MSC phenotype, differentiation, and tube formation capacity were preserved, but migration was reduced. DKD-MSC with and without interferon-γ priming inhibited T-cell proliferation greater than Control-MSC. DKD-MSC medium contained higher levels of anti-inflammatory cytokines (indoleamine 2,3-deoxygenase 1 and prostaglandin-E2) and prorepair factors (hepatocyte growth factor and stromal cell–derived factor 1) but lower IL-6 versus control-MSC medium. DKD-MSC medium protected high glucose plus transforming growth factor-β–exposed HK-2 cells by reducing apoptotic, fibrotic, and inflammatory marker expression. Few DKD-MSC functions were affected by patient characteristics, including age, sex, BMI, hemoglobin A1c, kidney function, and urine albumin excretion. However, senescence-associated β-galactosidase activity was lower in DKD-MSC from participants on metformin therapy. Therefore, while DKD altered the transcriptome and migratory function of culture-expanded MSCs, DKD-MSC functionality, trophic factor secretion, and immunomodulatory activities contributing to repair remained intact. These observations support testing of patient-derived MSC therapy and may inform preconditioning regimens in DKD clinical trials.