Giacomo Rossitto

The Role of Oxidized Low-Density Lipoproteins in Atherosclerosis: The Myths and the Facts

The oxidative modification hypothesis of atherosclerosis, which assigns to oxidized low-density lipoproteins (LDLs) a crucial role in atherosclerosis initiation and progression, is still debated. This review examines the role played by oxidized LDLs in atherogenesis taking into account data derived by studies based on molecular and clinical approaches. Experimental data carried out in cellular lines and animal models of atherosclerosis support the proatherogenic role of oxidized LDLs: (a) through chemotactic and proliferating actions on monocytes/macrophages, inciting their transformation into foam cells; (b) through stimulation of smooth muscle cells (SMCs) recruitment and proliferation in the tunica intima; (c) through eliciting endothelial cells, SMCs, and macrophages apoptosis with ensuing necrotic core development. Moreover, most of the experimental data on atherosclerosis-prone animals benefiting from antioxidant treatment points towards a link between oxidative stress and atherosclerosis. The evidence coming from cohort studies demonstrating an association between oxidized LDLs and cardiovascular events, notwithstanding some discrepancies, seems to point towards a role of oxidized LDLs in atherosclerotic plaque development and destabilization. Finally, the results of randomized clinical trials employing antioxidants completed up to date, despite demonstrating no benefits in healthy populations, suggest a benefit in high-risk patients. In conclusion, available data seem to validate the oxidative modification hypothesis of atherosclerosis, although additional proofs are still needed.

A Meta-Analysis of Somatic KCNJ5 K+ Channel Mutations In 1636 Patients With an Aldosterone-Producing Adenoma

CONTEXT Due to selection biases and inadequate statistical power, individual studies may fail to identify the clinical features of patients with an aldosterone-producing adenoma (APA) harboring KCNJ5 mutations. When this failure occurs, meta-analysis can provide significant outcome data. OBJECTIVE The objective was to determine the clinical features of these APA patients. DESIGN We systematically searched the PubMed, Scopus, Web of Science, and Cochrane databases library in January 2015 applying the Population, Intervention, Comparison, and Outcome (PICO) strategy. The standardized differences in mean and corresponding 95% confidence interval of continuous variables were computed by random-effects modeling. SETTING We performed a meta-analysis of all available studies on somatic KCNJ5 mutations in APA. PATIENTS We could identify 13 studies that recruited 1636 patients (age 49 ± 4 years; 55% females). MAIN OUTCOMES AND MEASURES Differences between APA with and without KCNJ5 mutations in gender, plasma renin activity, plasma aldosterone, tumor size, serum potassium, and blood pressure were investigated. RESULTS The overall prevalence of KCNJ5 mutations was 43% (range = 12-80%). Their rate was lower (P < .003) in the studies done in Europe, the United States, and Australia (35%) than in Japan and China (63%); it correlated (r = 0.60, P = .029) with the mean daily urinary sodium excretion. Compared with the wild-type, the mutated APA patients were younger (45 ± 3 vs 52 ± 5 yrs), had higher plasma aldosterone (42 ± 8 vs 33 ± 8 ng/dl), larger tumors (16.1 ± 6.4 versus 14.9 ± 7.4 mm), and were more often females (67% vs 44%) (all P < .05). CONCLUSIONS Meta-analysis showed that more pronounced hyperaldosteronism, young age, female gender, and larger tumors are the phenotypic features of APA patients with KCNJ5 mutations. No significant differences in blood pressure and serum K(+) was found, which suggests that these clinical features do not help in identifying mutated APA patients.

Galectin-3 Predicts Long-Term Cardiovascular Death in High-Risk Patients With Coronary Artery Disease

Objective— Galectin-3 (Gal-3) can affect atherogenesis by multiple mechanisms, but it remains scarcely known whether plasma Gal-3 levels predict cardiovascular events in patients with coronary artery disease. Therefore, we investigated if Gal-3 predicts cardiovascular death in patients with coronary artery disease of the Genetic and ENvironmental factors In Coronary Artery disease study. Approach and Results— In a prospective cohort study, we measured the plasma levels of Gal-3 in 1013 randomly selected patients who underwent coronary angiography and long-term follow-up to assess incident cardiovascular events. The primary end points were (1) cardiovascular death and (2) a composite of cardiovascular death, acute coronary syndrome, and stroke. Secondary end points entailed (1) acute myocardial infarction, (2) stroke, and (3) a composite fatal ischemic event including fatal myocardial infarction and stroke. The effect of Gal-3 on prognosis was assessed using Kaplan–Meier analysis and multivariate Cox’s regression. During long-term follow-up (median, 7.2 years), 115 cardiovascular deaths occurred (15.2%), more commonly in the high Gal-3 tertile (25.2%) than in the intermediate and the low tertiles (13.6% versus 7.5%, respectively; P<0.001). The adverse prognostic effect of high Gal-3 was confirmed in subgroup analysis of the patients with angiographically documented coronary artery disease and also of those with a normal left ventricular ejection fraction. At multivariate analysis, Gal-3 was a predictor of cardiovascular mortality (hazard ratio, 1.79; 95% confidence interval, 1.10–2.93; P=0.020) along with age, left ventricular ejection fraction, and coronary atherosclerotic burden. Conclusions— In high cardiovascular risk patients referred for coronary angiography Gal-3 is a strong independent predictor of cardiovascular death.

Elevation of Angiotensin-II Type-1-Receptor Autoantibodies Titer in Primary Aldosteronism as a Result of Aldosterone-Producing Adenoma

The mechanisms of excess aldosterone secretion in primary aldosteronism (PA) remain poorly understood, although a role for circulating factors has been hypothesized for decades. Agonistic autoantibodies against type-1 angiotensin-II receptor (AT1AA) are detectable in malignant hypertension and preeclampsia and might play a role in PA. Moreover, if they were elevated in aldosterone-producing adenoma (APA) and not in idiopathic hyperaldosteronism (IHA), they might be useful for discriminating between these conditions. To test these hypotheses, we measured the titer of AT1AA in serum of 46 patients with PA (26 with APA, 20 with IHA), 62 with primary hypertension (PH), 13 preeclamptic women, and 45 healthy normotensive blood donors.We found that the AT1AA titer was higher (P<0.05) in both PA and PH patients (2.65±1.55 and 1.86±0.63, respectively) than in normotensive subjects (1.00±0.20). In APA, it was 2-fold higher than in IHA patients (3.43±1.20 versus 1.64±1.39, respectively, P<0.001), despite similar blood pressure values. Of note, it allowed effective discrimination of APA from either PH or IHA, as shown by Receiver Operator Characteristics curve analysis. Moreover, after captopril challenge, plasma aldosterone concentration fell more in AT1AA-positive than in AT1AA-negative PA patients (–32.4% [21.1–42.9] versus 0.0% [0.0–22.6], P=0.015), suggesting an agonistic role for these autoantibodies. Thus, a higher serum AT1AA titer in patients with APA than in IHA and PH patients can be useful in differentiating APA patients from either PH or IHA, and thus in selecting PA patients to be submitted to adrenal vein sampling.

Treatment of atherosclerotic renovascular hypertension: review of observational studies and a meta-analysis of randomized clinical trials

Atherosclerotic renal artery stenosis can cause ischaemic nephropathy and arterial hypertension. We herein review the observational and randomized clinical trials (RCTs) comparing medical and endovascular treatment for control of hypertension and renal function preservation. Using the Population Intervention Comparison Outcome (PICO) strategy, we identified the relevant studies and performed a novel meta-analysis of all RCTs to determine the efficacy and safety of endovascular treatment when compared with medical therapy. The following outcomes were examined: baseline follow-up difference in mean systolic and diastolic blood pressure (BP), serum creatinine, number of drugs at follow-up, incident events (heart failure, stroke, and worsening renal function), mortality, cumulative relative risk of heart failure, stroke, and worsening renal function. Seven studies comprising a total of 2155 patients (1741 available at follow-up) were considered, including the recently reported CORAL Study. Compared with baseline, diastolic BP fell more at follow-up in patients in the endovascular than in the medical treatment arm (standard difference in means -0.21, 95% confidence interval (CI): -0.342 to -0.078, P = 0.002) despite a greater reduction in the mean number of antihypertensive drugs (standard difference in means -0.201, 95% CI: -0.302 to -0.1, P < 0.001). At variance, follow-up changes (from baseline) of systolic BP, serum creatinine, and incident cardiovascular event rates did not differ between treatment arms. Thus, patients with atherosclerotic renal artery stenosis receiving endovascular treatment required less anti-antihypertensive drugs at follow-up than those medically treated. Notwithstanding this, they evidenced a better control of diastolic BP.

Lipoprotein-associated phospholipase A2 prognostic role in atherosclerotic complications

Atherosclerosis manifests itself clinically at advanced stages when plaques undergo hemorrhage and/or rupture with superimposed thrombosis, thus abruptly stopping blood supply. Identification of markers of plaque destabilization at a pre-clinical stage is, therefore, a major goal of cardiovascular research. Promising results along this line were provided by studies investigating the lipoprotein-associated phospholipase A2 (Lp-PLA2), a member of phospholipase A2 proteins family that plays a key role in the metabolism of pro-inflammatory phospholipids, as oxidized low-density lipoproteins, and in the generation of pro-atherogenic metabolites, including lysophosphatidylcholine and oxidized free fatty acids. We herein review the experimental and clinical studies supporting use of Lp-PLA2 activity for predicting cardiovascular events. To his end we considered not only Lp-PLA2 activity and mass, but also Lp-PLA2 gene variations and their association with incident coronary artery disease, stroke, and cardiovascular mortality. Based on these evidences the major scientific societies have included in their guidelines the measurement of Lp-PLA2 activity among the biomarkers that are useful in risk stratification of adult asymptomatic patients at intermediate cardiovascular risk. The results of two recently published major clinical trials with the Lp-PLA2 inhibitor darapladib, which seem to challenge the pathogenic role of Lp-PLA2, will also be discussed.

Prospective validation of an automated chemiluminescence-based assay of renin and aldosterone for the work-up of arterial hypertension

Abstract Background: The availability of simple and accurate assays of plasma active renin (DRC) and aldosterone concentration (PAC) can improve the detection of secondary forms of arterial hypertension. Thus, we investigated the performance of an automated chemiluminescent assay for DRC and PAC in referred hypertensive patients. Methods: We prospectively recruited 260 consecutive hypertensive patients referred to an ESH Center for Hypertension. After exclusion of six protocol violations, 254 patients were analyzed: 67.3% had primary hypertension, 17.3% an aldosterone producing adenoma (APA), 11.4% idiopathic hyperaldosteronism (IHA), 2.4% renovascular hypertension (RVH), 0.8% familial hyperaldosteronism type 1 (FH-1), 0.4% apparent mineralocorticoid excess (AME), 0.4% a renin-producing tumor, and 3.9% were adrenalectomized APA patients. Bland-Altman plots and Deming regression were used to analyze results. The diagnostic accuracy (area under the curve, AUC of the ROC) of the DRC-based aldosterone-renin ratio (ARRCL) was compared with that of the PRA-based ARR (ARRRIA) using as reference the conclusive diagnosis of APA. Results: At Bland-Altman plot, the DRC and PAC assay showed no bias as compared to the PRA and PAC assay. A tight relation was found between the DRC and the PRA values (concordance correlation coefficient=0.92, p<0.0001) and the PAC values measured with radioimmunoassay and chemiluminescence (concordance correlation coefficient=0.93, p<0.001). For APA identification the AUC of the ARRCL was higher than that of the ARRRIA [0.974 (95% CI 0.940–0.991) vs. 0.894 (95% CI 0.841–0.933), p=0.02]. Conclusions: This rapid automated chemiluminescent DRC/PAC assay performed better than validated PRA/PAC radioimmunoassays for the identification of APA in referred hypertensive patients.

Antibodies to malondialdehyde oxidized low-density lipoproteins predict long term cardiovascular mortality in high risk patients

AIMS Antibodies to oxidized low-density lipoproteins (oxLDLAbs) are detectable in the serum of patients with and without atherosclerosis, but it is unclear if they play a pathogenic or a protective role in atherogenesis or if they are simply a marker of atherosclerosis. Therefore, in a prospective cohort study we investigated if oxLDLAbs titer predicts cardiovascular (CV) events in high-risk coronary artery disease patients. METHODS AND RESULTS The titer of IgG antibodies to malondialdehyde modified oxidized low-density lipoproteins was measured in 748 randomly selected patients of the GENICA study who underwent coronary angiography and assessment of incident CV events at follow-up. Patients were classified by oxLDLAbs into a low and a high titer group, corresponding to the first three and the last quartile, respectively. Cardiovascular event-free survival was compared between oxLDLAbs groups by Kaplan-Meier and multivariate technique including propensity score matching analysis. During long-term follow-up (median 7.2 years) CV deaths were observed in 65 patients (11.6%), more commonly in the high than in the low oxLDLAbs group (patients free from CV death 83.1% vs. 89% respectively, p=0.025). The incidence of CV events was also higher in the former than in latter (event-free survival 69.2% vs. 77.7% respectively, p=0.030). CONCLUSIONS An oxLDLAbs titer above the 75th percentile is a marker of LDL oxidation which predicts a worse CV prognosis at long term follow-up in high-risk Caucasian patients referred for coronary angiography.

Lipoprotein-Associated Phospholipase A2 Activity Predicts Cardiovascular Events in High Risk Coronary Artery Disease Patients

Objective Lipoprotein-associated phospholipase A2 (Lp-PLA2) is deemed to play a role in atherosclerosis and plaque destabilization as demonstrated in animal models and in prospective clinical studies. However, most of the literature is either focused on high-risk, apparently healthy patients, or is based on cross sectional studies. Therefore, we tested the hypothesis that serum Lp-PLA2 mass and activity are useful for predicting cardiovascular (CV) events over the coronary atherosclerotic burden and conventional risk factors in high-risk coronary artery disease patients. Methods and Results In a prospective cohort study of 712 Caucasian patients, who underwent coronary angiography and measurement of both Lp-PLA2 mass and activity at baseline, we determined incident CV events at follow-up after splitting the patients into a high and a low Lp-PLA2 mass and activity groups based on ROC analysis and Youden index. Kaplan-Meier and propensity score matching analysis were used to compare CV event-free survival between groups. Follow-up data were obtained in 75% of the cohort after a median of 7.2 years (range 1–12.7 years) during which 129 (25.5%) CV events were observed. The high Lp-PLA2 activity patients showed worse CV event-free survival (66.7% vs. 79.5%, p = 0.023) and acute coronary syndrome-free survival (75.4% vs. 85.6%, p = 0.04) than those in low Lp-PLA2 group. Conclusions A high Lp-PLA2 activity implies a worse CV prognosis at long term follow up in high-risk Caucasian patients referred for coronary angiography.

Metoclopramide unmasks potentially misleading contralateral suppression in patients undergoing adrenal vein sampling for primary aldosteronism.

Objective: As metoclopramide stimulates aldosterone secretion, we tested its usefulness in the assessment of lateralization of primary aldosteronism by adrenal vein sampling (AVS). Design: Prospective within-patient study in consecutive patients undergoing AVS for primary aldosteronism subtyping. Methods: We compared the diagnostic accuracy of baseline and postmetoclopramide lateralization index and relative (to cortisol) aldosterone secretion indices (RASI) for each adrenal gland with aldosterone-producing adenoma (APA) determined by the four corners criteria as the reference diagnosis. Results: We recruited 93 consecutive patients (mean age: 52 years; women 31%). Metoclopramide increased plasma aldosterone in the inferior vena cava and in both adrenal veins. The postmetoclopramide lateralization index was accurate in identifying APA, but did not increase diagnostic accuracy over baseline lateralization index, because the RASI increased similarly in both sides. Conversely, metoclopramide raised RASI to values more than 0.90 bilaterally in non-APA patients allowing accurate identification of factitious aldosterone suppression. In contrast, RASI was 0.90 or less in 48% contralateral to the tumor in APA patients. Regression analysis showed the APA patients with persistent suppression of RASI contralaterally showed a more florid primary aldosteronism phenotype. Conclusion: Metoclopramide does not enhance lateralization of aldosterone excess in APA, but consistently increased the value of RASI in non-APA cases, thus unmasking potentially misleading suppression of aldosterone. Postmetoclopramide RASI may therefore allow a more precise diagnosis when AVS can be achieved only unilaterally.