Intermittent Fasting After ST-Segment-Elevation Myocardial Infarction Improves Left Ventricular Function: The Randomized Controlled INTERFAST-MI Trial.

BACKGROUND: Intermittent fasting has shown positive effects on numerous cardiovascular risk factors. The INTERFAST-MI trial (Intermittent Fasting in Myocardial Infarction) has been designed to study the effects of intermittent fasting on cardiac function after STEM (ST-segment-elevation myocardial infarction) and the feasibility of future multicenter trials. METHODS: The INTERFAST-MI study was a prospective, randomized, controlled, nonblinded, single-center investigator-initiated trial. From October 1, 2020, to July 15, 2022, 48 patients were randomized to the study groups intermittent fasting or regular diet and followed for 6 months with follow-up visits at 4 weeks and 3 months. RESULTS: In all, 22 of 24 patients in the intermittent fasting group with a mean age of 58.54±12.29 years and 20 of 24 patients in the regular diet group with a mean age of 59.60±13.11 years were included in the intention-to-treat population. The primary efficacy end point (improvement in left ventricular ejection fraction after 4 weeks) was significantly greater in the intermittent fasting group compared with the control group (mean±SD, 6.636±7.122%. versus 1.450±4.828%; P=0.038). This effect was still significant and even more pronounced after 3 and 6 months. The patients in the intermittent fasting group showed a greater reduction in diastolic blood pressure and body weight compared with the control group. The mean adherence of patients in the intermittent fasting group was a median of 83.7% (interquartile range, 69.0%-98.4%) of all days. None of the patients from either group reported dizziness, syncope, or collapse. CONCLUSIONS: Our results suggest that intermittent fasting after myocardial infarction may be safe and could improve left ventricular function after STEMI. REGISTRATION: URL: https://www.drks.de; Unique identifier: DRKS00021784.

Empagliflozin prevents neointima formation by impairing smooth muscle cell proliferation and accelerating endothelial regeneration.

Background: Empagliflozin, an inhibitor of the sodium glucose co-transporter 2 (SGLT2) and developed as an anti-diabetic agent exerts additional beneficial effects on heart failure outcomes. However, the effect of empagliflozin on vascular cell function and vascular remodeling processes remains largely elusive. Methods/Results: Immunocytochemistry and immunoblotting revealed SGLT2 to be expressed in human smooth muscle (SMC) and endothelial cells (EC) as well as in murine femoral arteries. In vitro, empagliflozin reduced serum-induced proliferation and migration of human diabetic and non-diabetic SMCs in a dose-dependent manner. In contrast, empagliflozin significantly increased the cell count and migration capacity of human diabetic ECs, but not of human non-diabetic ECs. In vivo, application of empagliflozin resulted in a reduced number of proliferating neointimal cells in response to femoral artery wire-injury in C57BL/6J mice and prevented neointima formation. Comparable effects were observed in a streptozocin-induced diabetic model of apolipoprotein E-/- mice. Conclusive to the in vitro-results, re-endothelialization was not significantly affected in C57BL/6 mice, but improved in diabetic mice after treatment with empagliflozin assessed by Evan's Blue staining 3 days after electric denudation of the carotid artery. Ribonucleic acid (RNA) sequencing (RNA-seq) of human SMCs identified the vasoactive peptide apelin to be decisively regulated in response to empagliflozin treatment. Recombinant apelin mimicked the in vitro-effects of empagliflozin in ECs and SMCs. Conclusion: Empagliflozin significantly reduces serum-induced proliferation and migration of SMCs in vitro and prevents neointima formation in vivo, while augmenting EC proliferation in vitro and re-endothelialization in vivo after vascular injury. These data document the functional impact of empagliflozin on vascular human SMCs and ECs and vascular remodeling in mice for the first time.

Effect of intermittent fasting after ST-elevation myocardial infarction on left ventricular function: study protocol of a pilot randomised controlled trial (INTERFAST-MI).

INTRODUCTION: Preclinical studies consistently show robust disease-modifying effects of intermittent fasting in animal models of cardiovascular disease. However, the impact of intermittent fasting on cardiovascular endpoints after myocardial infarction has not been investigated in a clinical trial so far. METHODS AND ANALYSIS: The INTERmittent FASTing after Myocardial Infarction (INTERFAST-MI) trial is a monocentric prospective randomised controlled non-confirmatory pilot study including 48 patients with ST-segment elevation myocardial infarction. They will be randomised in a 1:1 ratio to either intermittent fasting (daily time-restricted eating; consuming food for not more than 8 hours/day, fasting for at least 16 hours/day) or to a control group without a particular diet. The follow-up time is 6 months. The prespecified primary outcome is change in left ventricular systolic function at 4 weeks from baseline to estimate effect size required to establishing sample size and power calculation for a future full-scale trial. Secondary outcomes include protocol adherence, recruitment, major adverse cardiac events, revascularisation, changes in left ventricular systolic function at 3 and 6 months, patient weight, blood pressure, and serum markers of inflammation and cardiovascular disease. Enrolment began on 1 November 2020 and is expected to conclude in December 2021. ETHICS AND DISSEMINATION: The trial has received ethics approval from the Medical Ethics Committee of the Martin-Luther-University Halle-Wittenberg. Results of the study will be submitted for publication in a peer-reviewed journal and presented at scientific conferences. TRIAL REGISTRATION NUMBER: DRKS00021784.

Toxic Epidermal Necrolysis Caused by Allopurinol: A Serious but Still Underestimated Adverse Reaction.

BACKGROUND Allopurinol is the first-line therapy for the treatment of symptomatic hyperuricemia (gout). In clinical practice, there is a tendency to overmedicate asymptomatic patients who have elevated serum urate. Because of this practice, serious and life-threatening reactions such as Stevens-Johnson syndrome (SJS) or the more dramatic toxic epidermal necrolysis (TEN), both frequently caused by uricostatics, may occur. To increase awareness of these complications, we present a case with fulminant TEN caused by allopurinol. CASE REPORT A 75-year-old woman noticed a mildly itching skin rash accompanied by fever, shivering, and weakness approximately 3 weeks after taking newly prescribed allopurinol. The initial clinical examination revealed a generalized maculopapular exanthema. An adverse drug reaction was recognized, and allopurinol was discontinued. Ambulatory supportive therapy using prednisolone and cetirizine was started but failed. The patient developed a progressive exanthema with painful widespread blistering, skin peeling, and mucosal and conjunctival lesions. After recurrent presentations to the Emergency Department, the patient was transferred to our Intensive Care Unit (ICU). The clinical picture confirmed the suspected diagnosis of TEN. Massive fluid replacement, prednisolone, and cyclosporine were used as anti-inflammatory therapy. Polyhexanide and octenidine were applied for local treatment. All treatment measures were guided daily by a multidisciplinary team. After 7 days in the ICU, the patient was transferred to the Dermatology Department and was discharged from the hospital 42 days later. CONCLUSIONS With the prescription of allopurinol, there should be awareness of potentially life-threatening complications such as SJS or TEN. Patients with SJS or TEN should be immediately transferred to an ICU with dermatological expertise and multidisciplinary therapy.

Landscape of T-cell repertoires with public COVID-19-associated T-cell receptors in pre-pandemic risk cohorts.

OBJECTIVES: T cells have an essential role in the antiviral defence. Public T-cell receptor (TCR) clonotypes are expanded in a substantial proportion of COVID-19 patients. We set out to exploit their potential use as read-out for COVID-19 T-cell immune responses. METHODS: We searched for COVID-19-associated T-cell clones with public TCRs, as defined by identical complementarity-determining region 3 (CDR3) beta chain amino acid sequence that can be reproducibly detected in the blood of COVID-19 patients. Of the different clonotype identification algorithms used in this study, deep sequencing of brain tissue of five patients with fatal COVID-19 delivered 68 TCR clonotypes with superior representation across 140 immune repertoires of unrelated COVID-19 patients. RESULTS: Mining of immune repertoires from subjects not previously exposed to the virus showed that these clonotypes can be found in almost 20% of pre-pandemic immune repertoires of healthy subjects, with lower representation in repertoires from risk groups like individuals above the age of 60 years or patients with cancer. CONCLUSION: Together, our data show that at least a proportion of the SARS-CoV-2 T-cell response is mediated by public TCRs that are present in repertoires of unexposed individuals. The lower representation of these clones in repertoires of risk groups or failure to expand such clones may contribute to more unfavorable clinical COVID-19 courses.

SARS-CoV-2-specific antibody rearrangements in prepandemic immune repertoires of risk cohorts and patients with COVID-19.

A considerable fraction of B cells recognize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with germline-encoded elements of their B cell receptor, resulting in the production of neutralizing and nonneutralizing antibodies. We found that antibody sequences from different discovery cohorts shared biochemical properties and could be retrieved across validation cohorts, confirming the stereotyped character of this naive response in coronavirus disease 2019 (COVID-19). While neutralizing antibody sequences were found independently of disease severity, in line with serological data, individual nonneutralizing antibody sequences were associated with fatal clinical courses, suggesting detrimental effects of these antibodies. We mined 200 immune repertoires from healthy individuals and 500 repertoires from patients with blood or solid cancers - all acquired prior to the pandemic - for SARS-CoV-2 antibody sequences. While the largely unmutated B cell rearrangements occurred in a substantial fraction of immune repertoires from young and healthy individuals, these sequences were less likely to be found in individuals over 60 years of age and in those with cancer. This reflects B cell repertoire restriction in aging and cancer, and may to a certain extent explain the different clinical courses of COVID-19 observed in these risk groups. Future studies will have to address if this stereotyped B cell response to SARS-CoV-2 emerging from unmutated antibody rearrangements will create long-lived memory.

BET bromodomain-containing epigenetic reader proteins regulate vascular smooth muscle cell proliferation and neointima formation.

AIMS: Recent studies revealed that the bromodomain and extra-terminal (BET) epigenetic reader proteins resemble key regulators in the underlying pathophysiology of cancer, diabetes, or cardiovascular disease. However, whether they also regulate vascular remodelling processes by direct effects on vascular cells is unknown. In this study, we investigated the effects of the BET proteins on human smooth muscle cell (SMC) function in vitro and neointima formation in response to vascular injury in vivo. METHODS AND RESULTS: Selective inhibition of BETs by the small molecule (+)-JQ1 dose-dependently reduced proliferation and migration of SMCs without apoptotic or toxic effects. Flow cytometric analysis revealed a cell cycle arrest in the G0/G1 phase in the presence of (+)-JQ1. Microarray- and pathway analyses revealed a substantial transcriptional regulation of gene sets controlled by the Forkhead box O (FOXO1)1-transcription factor. Silencing of the most significantly regulated FOXO1-dependent gene, CDKN1A, abolished the antiproliferative effects. Immunohistochemical colocalization, co-immunoprecipitation, and promoter-binding ELISA assay data confirmed that the BET protein BRD4 directly binds to FOXO1 and regulates FOXO1 transactivational capacity. In vivo, local application of (+)-JQ1 significantly attenuated SMC proliferation and neointimal lesion formation following wire-induced injury of the femoral artery in C57BL/6 mice. CONCLUSION: Inhibition of the BET-containing protein BRD4 after vascular injury by (+)-JQ1 restores FOXO1 transactivational activity, subsequent CDKN1A expression, cell cycle arrest and thus prevents SMC proliferation in vitro and neointima formation in vivo. Inhibition of BET epigenetic reader proteins might thus represent a promising therapeutic strategy to prevent adverse vascular remodelling.

Next-Generation Sequencing of T and B Cell Receptor Repertoires from COVID-19 Patients Showed Signatures Associated with Severity of Disease.

We profiled adaptive immunity in COVID-19 patients with active infection or after recovery and created a repository of currently >14 million B and T cell receptor (BCR and TCR) sequences from the blood of these patients. The B cell response showed converging IGHV3-driven BCR clusters closely associated with SARS-CoV-2 antibodies. Clonality and skewing of TCR repertoires were associated with interferon type I and III responses, early CD4+ and CD8+ T cell activation, and counterregulation by the co-receptors BTLA, Tim-3, PD-1, TIGIT, and CD73. Tfh, Th17-like, and nonconventional (but not classical antiviral) Th1 cell polarizations were induced. SARS-CoV-2-specific T cell responses were driven by TCR clusters shared between patients with a characteristic trajectory of clonotypes and traceability over the disease course. Our data provide fundamental insight into adaptive immunity to SARS-CoV-2 with the actively updated repository providing a resource for the scientific community urgently needed to inform therapeutic concepts and vaccine development.

Early Escalation of Mechanical Circulatory Support Stabilizes and Potentially Rescues Patients in Refractory Cardiogenic Shock.

BACKGROUND: Limited progress has been made in the management of cardiogenic shock (CS). Morbidity and mortality of refractory CS remain high. The effects of mechanical circulatory support (MCS) are promising, although many aspects are elusive. We evaluated efficacy and safety of early combined MCS (Impella microaxial pump + venoarterial extracorporeal membrane oxygenation [VA-ECMO]) in refractory CS and aimed to determine factors for decision-making in combined MCS. METHODS AND RESULTS: We analyzed 69 consecutive patients with refractory CS from our registry requiring combined MCS. In 12 cases, therapy was actively withdrawn according to patient's will. Patients were severely sick (Survival After Venoarterial ECMO score mean±SD, -8.9±4.4) predicting 30% in-hospital survival; ventilation 94%, dialysis 56%. Impella pumps and VA-ECMO were combined early (duration of combined MCS: median 94 hours; interquartile range, 49-150 hours). Early MCS escalation stabilized patients rapidly, reducing number and doses of catecholamines (P<0.05 versus baseline) while hemodynamics improved. Reflecting an improved microcirculation, lactate levels normalized within 24 hours (P<0.05 versus baseline). Despite refractory CS and disease severity, survival was favorable (on MCS 61%, 30 days 49%, 6 months 40%). In multivariate Cox-regression, duration of shock-to-first device (hours, hazard ratio, 1.05 [95% CI, 1.01-1.08]; P=0.007) and lactate levels after 12 hours of MCS (hazard ratio, 1.28 [95% CI, 1.09-1.51]; P=0.002) independently predicted survival. Additional right ventricular failure predisposed to futility (hazard ratio, 8.48 [95% CI, 1.85-38.91]; P=0.006). CONCLUSIONS: The early and consequent combination of MCS by Impella microaxial pumps and VA-ECMO enables stabilization and may rescue high-risk patients with refractory CS at low overall risk. Independent predictors of survival may guide prognostication, decision-making, and allocation of medical resources.

Senescence-induced inflammation: an important player and key therapeutic target in atherosclerosis.

Inflammation is a hallmark and potent driver of pathological vascular remodelling in atherosclerosis. However, current anti-inflammatory therapeutic strategies have shown mixed results. As an alternative perspective on the conundrum of chronic inflammation emerging evidence points towards a small subset of senescent cells as a critical player and central node driving atherosclerosis. Senescent cells belonging to various cell types are a dominant and chronic source of a large array of pro-inflammatory cytokines and various additional plaque destabilizing factors, being involved with various aspects of atherosclerosis pathogenesis. Antagonizing these key agitators of local chronic inflammation and plaque instability may provide a causative and multi-purpose therapeutic strategy to treat atherosclerosis. Anti-senescence treatment options with translational potential are currently in development. However, several questions and challenges remain to be addressed before these novel treatment approaches may enter the clinical setting.

Mortality in Patients With Out-of-Hospital Cardiac Arrest Undergoing a Standardized Protocol Including Therapeutic Hypothermia and Routine Coronary Angiography: Experience From the HACORE Registry.

OBJECTIVES: This study sought to analyze the impact of mandatory therapeutic hypothermia and cardiac catheterization in the absence of overt noncardiac cause of arrest as part of the Hannover Cardiac Resuscitation Algorithm before intensive care admission. BACKGROUND: Despite advanced therapies, out-of-hospital cardiac arrest (OHCA) is still associated with high mortality rates. Recently, the TTM (Target Temperature Management 33°C Versus 36°C After Out-of-Hospital Cardiac Arrest)-trial caused severe uncertainty about the efficacy of and need for therapeutic hypothermia. Furthermore, the role of early coronary angiography in OHCA survivors without ST-segment elevation remains undetermined. METHODS: In the HACORE (HAnnover Cooling REgistry) we investigated 233 consecutive patients (median age 64 [interquartile range: 53 to 74] years) with OHCA admitted to our institution between January 2011 and December 2015 who were treated according to the algorithm. RESULTS: A total of 73% had ventricular fibrillation as primary rhythm. Return of spontaneous circulation was achieved after 20 (interquartile range: 10 to 30) min. Immediate percutaneous coronary angiography was performed in 96% and coronary angioplasty in 59% of all cases. ST-segment elevation was present in 47%. Critical coronary stenosis requiring percutaneous coronary intervention was present in 67% of patients with and 52% of patients without ST-segment elevation. Overall 30-day intrahospital mortality in this real-world registry was 37%. Patients in our local registry who matched the inclusion/exclusion criteria of the TTM-trial (n = 145) had a markedly lower 30-day mortality (27%) compared with the published trial (44%). CONCLUSIONS: Standardized treatment of patients with OHCA following a strict protocol incorporating computed tomography, cardiac catheterization and revascularization, liberal use of active hemodynamic support in presence of shock, and mandatory therapeutic hypothermia results in mortality rates lower than previously reported.

Imaging of chemokine receptor CXCR4 expression in culprit and nonculprit coronary atherosclerotic plaque using motion-corrected [68Ga]pentixafor PET/CT.

PURPOSE: The chemokine receptor CXCR4 is a promising target for molecular imaging of CXCR4+ cell types, e.g. inflammatory cells, in cardiovascular diseases. We speculated that a specific CXCR4 ligand, [68Ga]pentixafor, along with novel techniques for motion correction, would facilitate the in vivo characterization of CXCR4 expression in small culprit and nonculprit coronary atherosclerotic lesions after acute myocardial infarction by motion-corrected targeted PET/CT. METHODS: CXCR4 expression was analysed ex vivo in separately obtained arterial wall specimens. [68Ga]Pentixafor PET/CT was performed in 37 patients after stent-based reperfusion for a first acute ST-segment elevation myocardial infarction. List-mode PET data were reconstructed to five different datasets using cardiac and/or respiratory gating. Guided by CT for localization, the PET signals of culprit and various groups of nonculprit coronary lesions were analysed and compared. RESULTS: Ex vivo, CXCR4 was upregulated in atherosclerotic lesions, and mainly colocalized with CD68+ inflammatory cells. In vivo, elevated CXCR4 expression was detected in culprit and nonculprit lesions, and the strongest CXCR4 PET signal (median SUVmax 1.96; interquartile range, IQR, 1.55-2.31) was observed in culprit coronary artery lesions. Stented nonculprit lesions (median SUVmax 1.45, IQR 1.23-1.88; P = 0.048) and hot spots in naive remote coronary segments (median SUVmax 1.34, IQR 1.23-1.74; P = 0.0005) showed significantly lower levels of CXCR4 expression. Dual cardiac/respiratory gating provided the strongest CXCR4 PET signal and the highest lesion detectability. CONCLUSION: We demonstrated the basic feasibility of motion-corrected targeted PET/CT imaging of CXCR4 expression in coronary artery lesions, which was triggered by vessel wall inflammation but also by stent-induced injury. This novel methodology may serve as a platform for future diagnostic and therapeutic clinical studies targeting the biology of coronary atherosclerotic plaque.

Vasa Vasorum Angiogenesis: Key Player in the Initiation and Progression of Atherosclerosis and Potential Target for the Treatment of Cardiovascular Disease.

Plaque microvascularization and increased endothelial permeability are key players in the development of atherosclerosis, from the initial stages of plaque formation to the occurrence of acute cardiovascular events. First, endothelial dysfunction and increased permeability facilitate the entry of diverse inflammation-triggering molecules and particles such as low-density lipoproteins into the artery wall from the arterial lumen and vasa vasorum (VV). Recognition of entering particles by resident phagocytes in the vessel wall triggers a maladaptive inflammatory response that initiates the process of local plaque formation. The recruitment and accumulation of inflammatory cells and the subsequent release of several cytokines, especially from resident macrophages, stimulate the expansion of existing VV and the formation of new highly permeable microvessels. This, in turn, exacerbates the deposition of pro-inflammatory particles and results in the recruitment of even more inflammatory cells. The progressive accumulation of leukocytes in the intima, which trigger proliferation of smooth muscle cells in the media, results in vessel wall thickening and hypoxia, which further stimulates neoangiogenesis of VV. Ultimately, this highly inflammatory environment damages the fragile plaque microvasculature leading to intraplaque hemorrhage, plaque instability, and eventually, acute cardiovascular events. This review will focus on the pivotal roles of endothelial permeability, neoangiogenesis, and plaque microvascularization by VV during plaque initiation, progression, and rupture. Special emphasis will be given to the underlying molecular mechanisms and potential therapeutic strategies to selectively target these processes.

Evidence for the use of mineralocorticoid receptor antagonists in the treatment of coronary artery disease and post-angioplasty restenosis.

Mineralocorticoid receptor antagonists (MRAs), such as spironolactone and eplerenone have an established role in the treatment of heart failure. However, many experimental and clinical studies have shown that aldosterone also plays a pivotal role in a variety of other pathophysiological conditions within the cardiovascular system. Aldosterone has been suggested to promote inflammation, endothelial dysfunction and smooth muscle cell hyperplasia during the development of atherosclerosis, thereby promoting the development of coronary artery disease (CAD). Since CAD and subsequent ischemic cardiomyopathy are the major causes of heart failure, it is of major interest, whether pharmacological therapy with MRAs among heart failure patients will also affect the common underlying conditions, namely, atherosclerosis and subsequent coronary vessel narrowing/rarefication. Therefore, in this article, we reviewed and discussed the preclinical and clinical evidence of MRAs for the treatment of acute or chronic vascular remodeling processes, such as atherosclerosis and post-angioplasty restenosis, which determine the progression of CAD and subsequent ischemic cardiomyopathy.

Sonic hedgehog-dependent activation of adventitial fibroblasts promotes neointima formation.

AIMS: Adventitial cells have been suggested to contribute to neointima formation, but the functional relevance and the responsible signalling pathways are largely unknown. Sonic hedgehog (Shh) is a regulator of vasculogenesis and promotes angiogenesis in the adult. METHODS AND RESULTS: Here we show that proliferation of vascular smooth muscle cells (SMC) after wire-induced injury in C57BL/6 mice is preceded by proliferation of adventitial fibroblasts. Simultaneously, the expression of Shh and its downstream signalling protein smoothened (SMO) were robustly increased within injured arteries. In vitro, combined stimulation with Shh and platelet-derived growth factor (PDGF)-BB strongly induced proliferation and migration of human adventitial fibroblasts. The supernatant of these activated fibroblasts contained high levels of interleukin-6 and -8 and strongly induced proliferation and migration of SMC. Inhibition of SMO selectively prevented fibroblast proliferation, cytokine release, and paracrine SMC activation. Mechanistically, we found that PDGF-BB activates protein kinase A in fibroblasts and thereby induces trafficking of SMO to the plasma membrane, where it can be activated by Shh. In vivo, SMO-inhibition significantly prevented the proliferation of adventitial fibroblasts and neointima formation following wire-induced injury. CONCLUSIONS: The initial activation of adventitial fibroblasts is essential for the subsequent proliferation of SMC and neointima formation. We identified SMO-dependent Shh signalling as a specific process for the activation of adventitial fibroblasts.

The novel mineralocorticoid receptor antagonist finerenone attenuates neointima formation after vascular injury.

BACKGROUND: The novel nonsteroidal mineralocorticoid receptor (MR) antagonist finerenone holds promise to be safe and efficient in the treatment of patients with heart failure and/or chronic kidney disease. However, its effects on vascular function remain elusive. PURPOSE: The aim of this study was to determine the functional effect of selective MR antagonism by finerenone in vascular cells in vitro and the effect on vascular remodeling following acute vascular injury in vivo. METHODS AND RESULTS: In vitro, finerenone dose-dependently reduced aldosterone-induced smooth muscle cell (SMC) proliferation, as quantified by BrdU incorporation, and prevented aldosterone-induced endothelial cell (EC) apoptosis, as measured with a flow cytometry based caspase 3/7 activity assay. In vivo, oral application of finerenone resulted in an accelerated re-endothelialization 3 days following electric injury of the murine carotid artery. Furthermore, finerenone treatment inhibited intimal and medial cell proliferation following wire-induced injury of the murine femoral artery 10 days following injury and attenuated neointimal lesion formation 21 days following injury. CONCLUSION: Finerenone significantly reduces apoptosis of ECs and simultaneously attenuates SMC proliferation, resulting in accelerated endothelial healing and reduced neointima formation of the injured vessels. Thus, finerenone appears to provide favorable vascular effects through restoring vascular integrity and preventing adverse vascular remodeling.

Targeting vasa vasorum dysfunction to prevent atherosclerosis.

Vasa vasorum are blood microvessels which penetrate the adventitia and outer layers of the media of large blood vessels, supplying them with nutrients and oxygen. A growing body of evidence suggests that vasa vasorum play a central role in the pathogenesis of atherosclerosis. In this review, we will make a case for the role of microvascular dysfunction in the initiation of disease. When seen through this lens, new therapeutic opportunities for prevention can be envisioned. In particular, we discuss how targeting the cellular metabolism and epigenetic machinery of vasa vasorum neovessels could be harnessed to render vasa vasorum endothelial cells less sensitive to atherogenic stimuli.

Targeting of Extracellular RNA Reduces Edema Formation and Infarct Size and Improves Survival After Myocardial Infarction in Mice.

BACKGROUND: Following myocardial infarction (MI), peri-infarct myocardial edema formation further impairs cardiac function. Extracellular RNA (eRNA) released from injured cells strongly increases vascular permeability. This study aimed to assess the role of eRNA in MI-induced cardiac edema formation, infarct size, cardiac function, and survival after acute MI and to evaluate the therapeutic potential of ribonuclease 1 (RNase-1) treatment as an eRNA-degrading intervention. METHODS AND RESULTS: C57BL/6J mice were subjected to MI by permanent ligation of the left anterior descending coronary artery. Plasma eRNA levels were significantly increased compared with those in controls starting from 30 minutes after ligation. Systemic application of RNase-1, but not DNase, significantly reduced myocardial edema formation 24 hours after ligation compared with controls. Consequently, eRNA degradation by RNase-1 significantly improved the perfusion of collateral arteries in the border zone of the infarcted myocardium 24 hours after ligation of the left anterior descending coronary artery, as detected by micro-computed tomography imaging. Although there was no significant difference in the area at risk, the area of vital myocardium was markedly larger in mice treated with RNase-1 compared with controls, as detected by Evans blue and 2,3,5-triphenyltetrazolium chloride staining. The increase in viable myocardium was associated with significantly preserved left ventricular function, as assessed by echocardiography. Moreover, RNase-1 significantly improved 8-week survival following MI. CONCLUSIONS: eRNA is an unrecognized permeability factor in vivo, associated with myocardial edema formation after acute MI. RNase-1 counteracts eRNA-induced edema formation and preserves perfusion of the infarction border zone, reducing infarct size and protecting cardiac function after MI.

Systemic application of sirolimus prevents neointima formation not via a direct anti-proliferative effect but via its anti-inflammatory properties.

BACKGROUND: Systemic treatment with sirolimus, as used for immunosuppression in transplant patients, results in markedly low rates of in-stent restenosis. Since the underlying mechanisms remain obscure, we aimed to determine the molecular and cellular effects of systemic sirolimus treatment on vascular remodeling processes. METHODS AND RESULTS: Systemic sirolimus treatment significantly reduced smooth muscle cell (SMC) proliferation 14days after wire-induced injury and neointima formation 28days after injury in C57BL/6 mice, while simultaneously impairing re-endothelialization. Interestingly, in vitro, sirolimus had no direct effect on the proliferation of SMC or endothelial cells (EC) at serum concentrations observed after systemic application. In contrast, sirolimus reduced the adhesion of leukocytes (CD45+) and bone marrow-derived progenitor cells (CD34+) to activated EC by down-regulating the adhesion molecules ICAM-1 and VCAM-1. In addition, sirolimus treatment also significantly reduced the upregulation of ICAM-1 and VCAM-1 and the recruitment of monocytic cells (MOMA-2+) in neointimal lesions in vivo. CONCLUSION: Our findings show that systemic sirolimus treatment effectively prevents SMC and EC proliferation in vivo without directly affecting these cells. Instead, sirolimus prevents neointima formation and re-endothelialization by attenuating the inflammatory response after injury with secondary effects on SMC and EC proliferation. Thus, despite a similar net effect, the mechanisms of systemic sirolimus treatment are largely different from the local effects achieved after application of sirolimus-eluting stents.