Low Density Lipoprotein Cholesterol Decreases the Expression of Adenosine A2A Receptor and Lipid Rafts-Protein Flotillin-1: Insights on Cardiovascular Risk of Hypercholesterolemia.

High blood levels of low-density lipoprotein (LDL)-cholesterol (LDL-C) are associated with atherosclerosis, mainly by promoting foam cell accumulation in vessels. As cholesterol is an essential component of cell plasma membranes and a regulator of several signaling pathways, LDL-C excess may have wider cardiovascular toxicity. We examined, in untreated hypercholesterolemia (HC) patients, selected regardless of the cause of LDL-C accumulation, and in healthy participants (HP), the expression of the adenosine A2A receptor (A2AR), an anti-inflammatory and vasodilatory protein with cholesterol-dependent modulation, and Flotillin-1, protein marker of cholesterol-enriched plasma membrane domains. Blood cardiovascular risk and inflammatory biomarkers were measured. A2AR and Flotillin-1 expression in peripheral blood mononuclear cells (PBMC) was lower in patients compared to HP and negatively correlated to LDL-C blood levels. No other differences were observed between the two groups apart from transferrin and ferritin concentrations. A2AR and Flotillin-1 proteins levels were positively correlated in the whole study population. Incubation of HP PBMCs with LDL-C caused a similar reduction in A2AR and Flotillin-1 expression. We suggest that LDL-C affects A2AR expression by impacting cholesterol-enriched membrane microdomains. Our results provide new insights into the molecular mechanisms underlying cholesterol toxicity, and may have important clinical implication for assessment and treatment of cardiovascular risk in HC.

Adenosinergic System and Neuroendocrine Syncope: What Is the Link?

Although very common, the precise mechanisms that explain the symptomatology of neuroendocrine syncope (NES) remain poorly understood. This disease, which can be very incapacitating, manifests itself as a drop in blood pressure secondary to vasodilation and/or extreme slowing of heart rate. As studies continue, the involvement of the adenosinergic system is becoming increasingly evident. Adenosine, which is an ATP derivative, may be involved in a large number of cases. Adenosine acts on G protein-coupled receptors with seven transmembrane domains. A1 and A2A adenosine receptor dysfunction seem to be particularly implicated since the activation leads to severe bradycardia or vasodilation, respectively, two cardinal symptoms of NES. This mini-review aims to shed light on the links between dysfunction of the adenosinergic system and NHS. In particular, signal transduction pathways through the modulation of cAMP production and ion channels in relation to effects on the cardiovascular system are addressed. A better understanding of these mechanisms could guide the pharmacological development of new therapeutic approaches.

Adenosine and Adenosine Receptors: Advances in Atrial Fibrillation.

Atrial fibrillation (AF) is the most common arrhythmia in the world. Because the key to developing innovative therapies that limit the onset and the progression of AF is to fully understand the underlying molecular mechanisms of AF, the aim of the present narrative review is to report the most recent advances in the potential role of the adenosinergic system in the pathophysiology of AF. After a comprehensive approach describing adenosinergic system signaling and the mechanisms of the initiation and maintenance of AF, we address the interactions of the adenosinergic system's signaling with AF. Indeed, adenosine release can activate four G-coupled membrane receptors, named A1, A2A, A2B and A3. Activation of the A2A receptors can promote the occurrence of delayed depolarization, while activation of the A1 receptors can shorten the action potential's duration and induce the resting membrane's potential hyperpolarization, which promote pulmonary vein firing, stabilize the AF rotors and allow for functional reentry. Moreover, the A2B receptors have been associated with atrial fibrosis homeostasis. Finally, the adenosinergic system can modulate the autonomous nervous system and is associated with AF risk factors. A question remains regarding adenosine release and the adenosine receptors' activation and whether this would be a cause or consequence of AF.

Adenosine Receptors Profile in Fibromuscular Dysplasia.

Fibromuscular dysplasia (FMD) is a non-inflammatory vascular disease that is characterized by unexplained systemic hypertension occurring in young people, associated with arterial stenosis, aneurysm rupture, intracranial/renal infarction, and stroke. Although the gold standard for the diagnosis remains catheter-angiography, biological markers would be helpful due to the delay from first symptom to diagnosis. Adenosine is an ATP derivative, that may be implicated in FMD pathophysiology. We hypothesized that changes in adenosine blood level (ABL) and production of adenosine receptors may be associated with FMD. Using peripheral blood mononuclear cells, we evaluated A1, A2A, and A2B receptor production by Western blot, in 67 patients (17 men and 50 women, mean (range) age 55 (29−77) years and 40 controls, 10 men and 30 women, mean (range) age 56 (37−70)). ABL was evaluated by liquid chromatography, mass spectrometry. ABL was significantly higher in patients vs. controls, mean (range): 1.7 (0.7−3) µmol/L vs. controls 0.6 (0.4−0.8) µmol/L (+180%) p < 0.001. While A1R and A2AR production did not differ in patients and controls, we found an over-production of A2BR in patients: 1.70 (0.90−2.40; arbitrary units) vs. controls = 1.03 (0.70−1.40), mean + 65% (p < 0.001). A2BR production with a cut off of 1.3 arbitrary units, gives a good sensitivity and specificity for the diagnosis. Production measurement of A2BR on monocytes and ABL could help in the diagnosis, especially in atypical or with poor symptoms.

Cardiac MRI Features and Prognostic Value in Immune Checkpoint Inhibitor-induced Myocarditis.

Background Cardiac MRI features are not well-defined in immune checkpoint inhibitor (ICI)-induced myocarditis (ICI-M), a severe complication of ICI therapy in patients with cancer. Purpose To analyze the cardiac MRI features of ICI-M and to explore their prognostic value in major adverse cardiovascular events (MACE). Materials and Methods In this retrospective study from May 2017 to January 2020, cardiac MRI findings (including late gadolinium enhancement [LGE], T1 and T2 mapping, and extracellular volume fraction [ECV] z scores) of patients with ICI-M were compared with those of patients with cancer scheduled to receive ICI therapy (pre-ICI group) and patients with viral myocarditis. As a secondary objective, the potential value of cardiac MRI for predicting MACE in patients with ICI-M by using Cox proportional hazards models was explored. Results Thirty-three patients with ICI-M (mean age ± standard deviation, 68 years ± 14; 23 men) were compared with 21 patients scheduled to receive to ICI therapy (mean age, 65 years ± 14; 14 men) and 85 patients with viral myocarditis (mean age, 32 years ± 13; 67 men). Compared with the pre-ICI group, patients with ICI-M showed higher global native T1, ECV, and T2 z scores (0.03 ± 0.85 vs 1.79 ± 1.93 [P < .001]; 1.34 ± 0.57 vs 2.59 ± 1.97 [P = .03]; and -0.76 ± 1.41 vs 0.88 ± 1.96 [P = .002], respectively), and LGE was more frequently observed (27 of 33 patients [82%] vs two of 21 [10%]; P < .001). LGE was less frequent in patients with ICI-M than those with viral myocarditis (27 of 33 patients [82%] vs 85 of 85 [100%]; P < .001) but was more likely to involve the septal segments (16 of 33 patients [48%] vs 25 of 85 [29%]; P < .001) and midwall layer (11 of 33 patients [33%] vs two of 85 [2%]; P < .001). Septal LGE was the only cardiac MRI predictor of MACE at 1 year even after adjustment for peak troponin (adjusted hazard ratio, 2.7 [95% CI: 1.1, 6.7]; P = .03). Conclusion Cardiac MRI features of immune checkpoint inhibitor (ICI)-induced myocarditis (ICI-M) seem to differ from those in patients scheduled to receive ICIs and patients with viral myocarditis. Septal late gadolinium enhancement might be a predictor of major cardiovascular events in patients with ICI-M. Clinical trial registration no. NCT03313544 © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Edelman and Pursnani in this issue.

Intensified immunosuppressive therapy in patients with immune checkpoint inhibitor-induced myocarditis.

BACKGROUND: Myocarditis is a rare but life-threatening adverse event of cancer treatments with immune checkpoint inhibitors (ICIs). Recent guidelines recommend the use of high doses of corticosteroids as a first-line treatment, followed by intensified immunosuppressive therapy (IIST) in the case of unfavorable evolution. However, this strategy is empirical, and no studies have specifically addressed this issue. Therefore, we aimed to investigate and compare the clinical course, management and outcome of ICI-induced myocarditis patients requiring or not requiring IIST. METHODS: This case-control study included all patients consecutively admitted to The Mediterranean University Center of Cardio-Oncology (Aix-Marseille University, France) for the diagnosis of ICI-induced myocarditis according to Bonaca's criteria and treated with or without IIST. In addition, we searched PubMed and included patients from previously published case reports treated with IIST in the analysis. The clinical, biological, imaging, treatment, all-cause death and cardiovascular death data of patients who required IIST were compared with those of patients who did not. RESULTS: A total of 60 patients (69±12 years) were included (36 were treated with IIST and 24 were not). Patients requiring IIST were more likely to have received a combination of ICIs (39% vs 8%, p=0.01), and developed the first symptoms/signs of myocarditis earlier after the onset of ICI therapy (median, 18 days vs 60 days, p=0.002). They had a significantly higher prevalence of sustained ventricular arrhythmia, complete atrioventricular block, cardiogenic shock and troponin elevation. Moreover, they were more likely to have other immune-related adverse events simultaneously (p<0.0001), especially myositis (p=0.0002) and myasthenia gravis (p=0.009). Patients who required IIST were more likely to die from any cause (50% vs 21%, p=0.02). Among them, patients who received infliximab were more likely to die from cardiovascular causes (OR, 12.0; 95% CI 2.1 to 67.1; p=0.005). CONCLUSION: The need for IIST was more common in patients who developed myocarditis very early after the start of ICI therapy, as well as when hemodynamic/electrical instability or neuromuscular adverse events occurred. Treatment with infliximab might be associated with an increased risk of cardiovascular death.

Management and research in cancer treatment-related cardiovascular toxicity: Challenges and perspectives.

Cardiovascular toxicity is a potentially serious complication that can result from the use of various cancer therapies and can impact the short- and long-term prognosis of treated patients as well as cancer survivors. In addition to their potential acute cardiovascular adverse events, new treatments can lead to late toxicity even after their completion because patients who survive longer generally have an increased exposure to the cancer therapies combined to standard cardiovascular risk factors. These complications expose the patient to the risk of cardiovascular morbi-mortality, which makes managing cardiovascular toxicity a significant challenge. Cardio-oncology programs offer the opportunity to improve cardiovascular monitoring, safety, and management through a better understanding of the pathogenesis of toxicity and interdisciplinary collaborations. In this review, we address new challenges, perspectives, and research priorities in cancer therapy-related cardiovascular toxicity to identify strategies that could improve the overall prognosis and survival of cancer patients. We also focus our discussion on the contribution of cardio-oncology in each step of the development and use of cancer therapies.

Aldosterone regulation of T-type calcium channels.

Voltage-operated calcium channels play a crucial role in signal transduction in many excitable and non-excitable cell types. While a rapid modulation of their activity by hormone-activated kinases and/or G proteins has been recognized for a long time, a sustained control of their expression level has been only recently demonstrated. In adrenal H295R cells, for example, aldosterone treatment selectively increased low threshold T-type calcium current density without affecting L-type currents. Antagonizing the mineralocorticoid receptor (MR) with spironolactone prevented aldosterone action on T-type currents. By RT-PCR, we detected in these cells the presence of two different isoforms of L-type channels, alpha(1)C and alpha(1)D, and one isoform of T channel, alpha(1)H. A second T channel isoform (alpha(1)G) was also observed under particular culture conditions. Quantification of the specific messenger RNA by real time RT-PCR allowed us to show a 40% increase of the alpha1H messenger levels upon aldosterone treatment (alpha(1)G was insensitive), a response that was also completely prevented by spironolactone. Because T-type, but not L-type channel activity is linked to steroidogenesis, this modulation represents a positive, intracrine feed back mechanism exerted by aldosterone on its own production. Aldosterone has been also implicated in the pathogenesis and progression of ventricular hypertrophy and heart failure independently of its action on arterial blood pressure. We have observed that, in rat neonatal cardiomyocytes, aldosterone increases (by two-fold) L-type calcium current amplitude in ventricular but not in atrial cells. No significant effect of aldosterone could be detected on T-type currents, that were much smaller than L-type currents in these cells. However, aldosterone exerted opposite effects on T channel isoform expression, increasing alpha(1)H and decreasing alpha(1)G. Although the functional role of T channels is still poorly defined in ventricular cardiomyocytes, an overexpression of alpha(1)H could be partially responsible for the arrhythmias linked to hyperaldosteronism.Finally, T channels also appear to be involved in the neuroendocrine differentiation of prostate epithelial cells, a poor prognosis in prostate cancer. We have shown that the only calcium channel expressed in the prostatic LNCaP cells is the alpha(1)H isoform and that induction of cell differentiation with cAMP leads to a concomitant increase in both T-type current and alpha(1)H mRNA. In spite of the presence of MR in these cells, aldosterone only modestly increased alpha(1)H mRNA levels. A functional role for these channels was suggested by the observation that low nickel concentrations prevent neuritic process outgrowth. In conclusion, it appears that T-type calcium channel expression vary in different patho-physiological conditions and that aldosterone, in several cell types, is able to modulate this expression.

Overexpression of an alpha 1H (Cav3.2) T-type calcium channel during neuroendocrine differentiation of human prostate cancer cells.

Neuroendocrine differentiation of prostate epithelial cells is usually associated with an increased aggressivity and invasiveness of prostate tumors and a poor prognosis. However, the molecular mechanisms involved in this process remain poorly understood. We have investigated the possible expression of voltage-gated calcium channels in human prostate cancer epithelial LNCaP cells and their modulation during neuroendocrine differentiation. A small proportion of undifferentiated LNCaP cells displayed a voltage-dependent calcium current. This proportion and the calcium current density were significantly increased during neuroendocrine differentiation induced by long-term treatments with cyclic AMP permeant analogs or with a steroid-reduced culture medium. Biophysical and pharmacological properties of this calcium current suggest that it is carried by low-voltage activated T-type calcium channels. Reverse transcriptase-PCR experiments demonstrated that only a single type of LVA calcium channel mRNA, an alpha(1H) calcium channel mRNA, is expressed in LNCaP cells. Quantitative real-time reverse transcriptase-PCR revealed that alpha(1H) mRNA was overexpressed during neuroendocrine differentiation. Finally, we show that this calcium channel promotes basal calcium entry at resting membrane potential and may facilitate neurite lengthening. This voltage-dependent calcium channel could be involved in the stimulation of mitogenic factor secretion and could therefore be a target for future therapeutic strategies.