Valeria Bisogni

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.

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.

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.

The sympathetic nervous system and catecholamines metabolism in obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is the most common sleep disorder of breathing in middle-aged and overweight subjects. It features recurrent episodes of upper airway total (apnoea) o partial (hypopnea) collapse during sleep, which are associated with a reduction in blood oxygen saturation and with arousal from sleep to re-establish airway patency. An association of OSA with dysregulation of the autonomous nervous system (ANS) and altered catecholamines (CAs) metabolism has been contended for years. However, the pathophysiology mechanisms underlying these alterations remain to be fully clarified. Nonetheless, these alterations are deemed to play a key pathogenic role in the established association of OSA with several conditions besides arterial hypertension (HT), including coronary artery disease, stroke, and, more in general, with increased risk of cardiovascular (CV) events. Hence, in this review we will analyse the relationship between the sleep disturbances associated with OSA and the altered function of the ANS, including CAs metabolism.

Apparent mineralcorticoid excess syndrome, an often forgotten or unrecognized cause of hypokalemia and hypertension: Case report and appraisal of the pathophysiology

Abstract The glicyrrhizic acid, contained in licorice, has a mineralcorticoid-like effect. Chronic excess intake of licorice induces the rare syndrome of “apparent mineralcorticoid excess”, due to the inhibitory effect of glicyrrhizic acid on 11 β-hydroxysteroid dehydrogenase type 2 determining clinical/biochemical manifestations as resistant hypertension, metabolic alkalosis and severe hypokalemia. We report a typical clinical case of licorice abuse to emphasize the importance of a detailed anamnesis, which is essential for the diagnosis, avoid unnecessary and expensive investigations, and reduce the duration of hospitalization. We also provide an appraisal of the pathophysiology of “apparent mineralcorticoid excess” syndrome, still an often forgotten or unrecognized cause of hypokalemia and hypertension.

Androstenedione and 17-α-Hydroxyprogesterone Are Better Indicators of Adrenal Vein Sampling Selectivity Than CortisolNovelty and Significance

For identification of potentially surgically curable primary aldosteronism, guidelines recommend use of adrenal vein sampling (AVS) that requires selective catheterization of both adrenal veins as verified by using the cortisol-derived selectivity index. Unfortunately, bilaterally selective studies are not obtained under unstimulated conditions in a proportion of the cases ranging between 15% and 50% depending on the cutoff used. We therefore investigated whether 17-&agr;-hydroxyprogesterone and androstenedione, which showed a higher step-up between adrenal vein and inferior vena cava blood than cortisol, can ascertain selectivity when cortisol failed to do so. We prospectively recruited 32 hypertensive patients with confirmed primary aldosteronism, who underwent bilaterally simultaneous sampling without cosyntropin stimulation and with the same predefined AVS protocol. All were consecutively selected because of a cortisol-based selectivity index <2.00 in at least one of the paired adrenal vein blood samples collected as per protocol. Results showed that the values of the selectivity index based on 17-&agr;-hydroxyprogesterone and androstenedione were higher (P<0.01) on average by 1.6- and 12-fold, respectively, than those based on cortisol. With use of these steroids, we rescued 43% and 73% of the AVS, respectively, from being judged nonselective. Thus, in challenging patients with primary aldosteronism submitted to AVS use of 17-&agr;-hydroxyprogesterone, and even more so of androstenedione, for ascertaining selectivity allows demonstration of correct catheter placement in a proportion of AVS studies better than cortisol. Thus, replacing cortisol measurement with these steroids, and particularly androstenedione, can improve the diagnostic yield of AVS.

Response to Effectiveness of Adrenalectomy and Aldosterone Antagonists for Long-Term Treatment of Primary Aldosteronism

Our data demonstrated the efficacy of mineralocorticoid receptor (MR) blockers for the treatment of primary aldosteronism (PA).1 However, by no means did we interpret our findings to show the superiority of adrenalectomy over MR blocker therapy. The higher rate of cure of hypertension seen with surgery was intrinsic with the definition of cure: 42% of our adrenalectomized versus none of our medically treated patients could withdraw pharmacological treatment at long term. Hence, when guided by results of adrenal vein sampling, adrenalectomy provides long-term cure of hypertension and allows tapering, or withdrawal, of the antihypertensive medications. Comparing adrenalectomy and MR blockade would require randomization of PA patients to either treatment. Neither the study of Reincke et …

In Patients with Chronic Kidney Disease Short Term Blood Pressure Variability is Associated with the Presence and Severity of Sleep Disorders

Background/Aims: In chronic kidney disease (CKD) patients blood pressure variability (BPV) is associated with poor outcome. Sleep disturbances alter BP profiles in hypertensives but their influence on BPV in CKD patients is unknown. We screened a cohort of CKD/ESRD patients to investigate whether sleep quality impacts on BPV. Methods: Consecutive CKD patients’ sleep quality was assessed using validated questionnaires (Epworth Sleepiness Scale-ESS); International Restless legs scale-IRLS; Functional Outcomes of Sleep Questionnaire-FOSQ: Insomnia Severity Index-ISI; STOP-Bang). All patients underwent ambulatory blood pressure measurement. Results: 104 out of 143 enrolled patients (78.32% stage-3 CKD; 10.49% Stage-4; 11.19% Stage-5; 6.99% ESRD-under dialysis) completed all the questionnaires. 95.8% were hypertensives, 70% were non-dippers and 27.8% had resistant hypertension. STOP-Bang>4 proved sleep disorders in 84.84% of patients. Patients with IRLS>10 had greater diastolic nocturnal standard deviation (DNSD) and a trend (p=0.05) for systolic nocturnal SD (SNSD). Patients with ISI>14 had greater SNSD and in 28.8% FOSQ showed severely impaired sleep quality. Their systolic nocturnal BPV was significantly greater. ISI was independently associated with SNSD. FOSQ and diastolic nocturnal BPV were negatively correlated at the bivariate analysis and FOSQ independently predicts systolic nocturnal BPV at multivariate regression analysis. Conclusions: In CKD patients impaired sleep quality increases BPV, might contribute to their disease progression and worsen prognosis. Searching for sleep problems in CKD patients could help planning their treatment of sleep problems contributing to CV risk reduction. Our data provide the rationale working hypothesis for the need of studies with larger number of patients aimed to demonstrate improved outcome of CKD progression and CV risk with the treatment also of sleep disorders.

Quantitative value of aldosterone-renin ratio for detection of aldosterone-producing adenoma: The Aldosterone-Renin Ratio for Primary Aldosteronism (AQUARR) study

Background Current guidelines recommend use of the aldosterone‐renin ratio (ARR) for the case detection of primary aldosteronism followed by confirmatory tests to exclude false‐positive results from further diagnostic workup. We investigated the hypothesis that this could be unnecessary in patients with a high ARR value if the quantitative information carried by the ARR is taken into due consideration. Methods and Results We interrogated 2 large data sets of prospectively collected patients studied with the same predefined protocol, which included the captopril challenge test. We used an unambiguous diagnosis of aldosterone‐producing adenoma as reference index. We also assessed whether the post‐captopril ARR and plasma aldosterone concentration fall furnished a diagnostic gain over baseline ARR values. We found that the false‐positive rate fell exponentially, and, conversely, the specificity increased with rising ARR values. At receiver operating characteristics curves and diagnostic odds ratio analysis, the high baseline ARR values implied very high positive likelihood ratio and diagnostic odds ratio values. The baseline and post‐captopril ARR showed similar diagnostic accuracy (area under the receiver operating characteristics curve) in both the exploratory and validation cohorts, indicating lack of diagnostic gain with this confirmatory test (between‐area under the curve difference, 0.005; 95% CI, −0.031 to 0.040; P=0.7 for comparison, and 0.05; 95% CI, −0.061 to 0.064; P=0.051 for comparison, respectively). Conclusions These results indicate that the ARR conveys key quantitative information that, if properly used, can simplify the diagnostic workup, resulting in saving of money and resources. This can offer the chance of diagnosis and ensuing adrenalectomy to a larger number of hypertensive patients, ultimately resulting in better control of blood pressure.

Assessment of the Quantitative Value Usefulness of the Aldosterone-Renin Ratio (ARR) for Primary Aldosteronism (AQUARR) Study.

Current guidelines recommend use of the aldosterone-renin ratio (ARR) for the case detection of primary aldosteronism (PA), the most common cause of secondary hypertension, in selected hypertensive patients. “Confirmatory” tests are then recommended in patients who tested positive at the ARR to exclude from further diagnostic work-up false positive results. Based on our experience we hypothesized that the ARR carries quantitative information, which can avoid the need of confirmatory tests. We herein describe a study protocol to identify the ARR cut-off value with a high specificity for the exclusion of aldosterone-producing adenoma (APA) based on analysis of two large prospectively collected datasets of patients in which a conclusive diagnosis of APA was made by the four corners criteria. This will also serve to investigate the diagnostic gain provided over this ARR cut-off value by one confirmatory test, the captopril challenge test. Hence, with this protocol we expect to identify an ARR cut-off value that might prevent further testing in patients with either a low or a high probability of APA. This could translate in a higher diagnostic accuracy and, by preventing unnecessary invasive testing, into a substantial saving of money, time, and resources.