Archiv für Kreislaufforschung

CD40L–CD40–TRAF signaling plays a role in atherosclerosis progression and affects the pathogenesis of coronary heart disease (CHD). We tested the hypothesis that CD40L–CD40–TRAF signaling is a potential therapeutic target in hyperlipidemia, diabetes, and hypertension. In mouse models of hyperlipidemia plus diabetes (db/db mice) or hypertension (1 mg/kg/d angiotensin-II for 7 days), TRAF6 inhibitor treatment (2.5 mg/kg/d for 7 or 14 days) normalized markers of oxidative stress and inflammation. As diabetes and hypertension are important comorbidities aggravating CHD, we explored whether the CD40L–CD40–TRAF signaling cascade and their associated inflammatory pathways are expressed in CHD patients suffering from comorbidities. Therefore, we analyzed vascular bypass material (aorta or internal mammary artery) and plasma from patients with CHD with diabetes and/or hypertension. Our Olink targeted plasma proteomic analysis using the IMMUNO-ONCOLOGY panel revealed a pattern of step-wise increase for 13/92 markers of low-grade inflammation with significant changes. CD40L or CD40 significantly correlated with 38 or 56 other inflammatory targets. In addition, specific gene clusters that correlate with the comorbidities were identified in isolated aortic mRNA of CHD patients through RNA-sequencing. These signaling clusters comprised CD40L–CD40–TRAF, immune system, hemostasis, muscle contraction, metabolism of lipids, developmental biology, and apoptosis. Finally, immunological analysis revealed key markers correlated with comorbidities in CHD patients, such as CD40L, NOX2, CD68, and 3-nitrotyrosine. These data indicate that comorbidities increase inflammatory pathways in CHD, and targeting these pathways will be beneficial in reducing cardiovascular events in CHD patients with comorbidities.

Chronic activation of Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway contributes to vascular inflammation and atherosclerosis by inducing expression of genes involved in cell proliferation, differentiation and migration. We aimed to investigate whether enforced expression of negative regulators, the suppressors of cytokine signaling (SOCS1 and SOCS3), inhibits harmful JAK/STAT-mediated responses and affects atherosclerosis in apolipoprotein E knockout mice. Adenovirus-mediated SOCS1 transgene expression impaired the onset and progression of atherosclerosis without impact on lipid profile, whereas SOCS3 was only effective on early atherosclerosis. Mechanistically, SOCS gene delivery, primarily SOCS1, attenuated STAT1 and STAT3 activation and reduced the expression of STAT-dependent genes (chemokine/chemokine receptors, adhesion molecules, pro-inflammatory cytokines and scavenger receptors) in aortic tissue. Furthermore, atherosclerotic plaques exhibit a more stable phenotype characterized by lower lipids, T cells and M1 macrophages and higher M2 macrophages and collagen. Atheroprotection was accompanied by a systemic alteration of T helper- and T regulatory-related genes and a reduced activation state of circulating monocytes. In vascular smooth muscle cells and macrophages, SOCS gene delivery inhibited cytokine-induced STAT activation, pro-inflammatory gene expression, cell migration and proliferation. In conclusion, targeting SOCS proteins, predominantly SOCS1, to suppress pathological mechanisms involved in atheroma plaque progression and destabilization could be an interesting anti-atherosclerotic strategy.

Ligation of the anterior descending coronary artery two-thirds from its origin in the pig was found to precipitate ventricular arrhythmias and fibrillation, starting approximately 20 min post-ligation, which were associated with regional accumulation of myocardial cAMP in the ischaemic area. When the arrhythmias stopped, cyclic AMP levels in the ischaemic zone were decreased. Arrhythmias could then be induced by subepicardial infusion (10 μl/min) close to the visible edge of ischaemia of cAMP analogues [N6-monobutyryl cAMP, N6,O2-dibutyryl cAMP (5·102M each)] or agents which increase the myocardial contents of cAMP. These agents were: isoproterenol (10−6 M), noradrenalin, adrenalin (10−5 M each), glucagon, histamine (10−3 M each), theophylline and caffeine (5·10−2 M each). Also active were dopamine (10−3 M), oubain (10−5 M) and aconitine (10−6 M). The arrhythmias induced by infusion of catecholamines were dependent on Ca2+ and were abolished by beta-adrenoceptor blocking agents (pindolol, 10−6 M) and calcium antagonists (isoptin, D 600, 10−4 M each). Infusion of 150 mM sodium chloride or 100 mM sodium butyrate did not precipitate arrhythmias. It is concluded that myocardial cAMP may play an important role in the genesis of ventricular arrhythmias in the ischaemic heart, probably by augmenting the slow calcium inward current.

Hemodynamics and myocardial contractility were evaluated in five unanesthetized calves during acute hypocapnic and isocapnic hypoxia and during acute hypocapnic hypoxia with beta-adrenergic blockade. Both hypocapnic and isocapnic hypoxia, with mean PaO 2 levels of 33.1 and 39.1 mm Hg respectively, produced a decline in stroke volume and index, while cardiac output and index were maintained at normoxic control levels by an increase in heart rate. Evaluation of myocardial contractility indices suggested an augmentation of left ventricular contractility during both hypocapnic and isocapnic hypoxia. Betaadrenergic blockade effectively eliminated the increase in left ventricular contractility during hypocapnic hypoxia, suggesting an important role of the adrenergic nervous system in the genesis of the cardiovascular response of the calf to acute hypoxia. Right ventricular contractility indices failed to demonstrate a clear-cut augmentation of contractility during hypocapnic and isocapnic hypoxia when the concurrent increase in afterload was considered. Mean pulmonary arterial blood pressure rose significantly during hypocapnic and isocapnic hypoxia. The pulmonary pressor response to hypocapnic hypoxia was significantly augmented by beta blockade, indicating that the autonomic nervous system is capable of modifying the hypoxic pulmonary pressor response in this species.

Platelet activation and aggregation in the coronary circulation may be important in the pathogenesis of myocardial ischemia. Molsidomine (M), isosorbide dinitrate (ISDN) and nitroglycerin (NTG) have been found to inhibit platelet aggregationin vitro. In the present study, the activity of these compounds was investigated in a model of coronary artery thrombosisin vivo. Dogs were ancsthetized, thoracotomized, and their heart was exposed. An electrode was inserted into the left circumflex coronary artery and set to rest on the intima. Electrical stimulation (9 V, 150 μA) lasted for 6 h. Compounds (each in 2 dose levels) were given as an i.v. infusion starting 30 min after the beginning of the stimulation and lasting for the duration of the experiment. All control (saline-treated) animals underwent thrombotic occlusion of the coronary artery as assessed by flow measurement. On the other hand, 2/8 dogs treated with the lower M dose and 4/8 dogs treated with the higher M dose did not have a coronary occlusion. Neither ISDN nor NTG, at both doses, prevented the coronary occlusion. In control animals thrombus wet weight was 74.43±11.25 mg. M reduced the thrombus weight in a doserelated manner, while ISDN (marginally) and NTG (significantly at the higher dose) increased this parameter. Following the coronary thrombosis, all control animals developed myocardial infarcts as assessed by the tetrazolium technique. Similarly all animals treated with ISDN and with NTG (at both doses) showed infarcts. However, 3/8 M-dogs did not have a myocardial infarction in the lower as well as in the higher dose groups. The hemodynamic changes induced by the 3 compounds were similar in magnitude. Thus M but not ISDN or NTG showed in thisin-vivo study antithrombotic and consequently antiischemic activity.

The effects ofmyocardial ischaemia on twomitochondrial preparations (polytron and nagarse) were evaluated, using three different substrates to localize the defect in the electron transport chain. Coronary artery ligation and normothermic ischaemic arrest (NICA) of the isolated working perfused rat heart were used as models of ischaemia. The results showed that, although the degree to which these two mitochondrial preparations were affected by ischaemia might differ, mitochondrial function was altered in a similar manner. After 20 min of NICA, the polytron mitochondria appeared to be more susceptible to injury than the nagarse fraction. However, coronary artery ligation for 55 min depressed the QO2 (State 3) values of polytron and nagarse mitochondria to the same extent. Moderate ischaemia (coronary artery ligation for 55 min or NICA for 20 min) depressed the oxidative phosphorylation function of both mitochondrial populations with glutamate as substrate only, indicating that the NADH-coenzyme Q region of the electron transport chain is most sensitive to ischaemic injury. As the period and severity of ischaemia increased, the rest of the electron transport chain and the phosphorylating capacity of the mitochondria became depressed. In moderate ischaemia, addition of exogenous cytochrome C caused a complete return to normal QO2 values of both mitochondrial preparations. However, in severe ischaemia (55 min NICA), although cytochrome C improved mitochondrial oxygen uptake, the values were still significantly lower than those of control hearts.