Amiodarone inhibits interleukin 6 production and attenuates myocardial injury induced by viral myocarditis in mice

Cardioprotective effects of amiodarone in a rat model of epilepsy-induced cardiac dysfunction

Cardiac dysfunction is one of the leading causes of death in epilepsy. The anti-arrhythmic drug, amiodarone, is under investigation for its therapeutic effects in epilepsy. We aimed to evaluate the possible effects of amiodarone on cardiac injury during status epilepticus, as it can cause prolongation of the QT interval. Five rat groups were enrolled in the study; three control groups (1) Control, (2) Control-lithium and (3) Control-Amio, treated with 150 mg/kg/intraperitoneal amiodarone, (4) Epilepsy model, induced by sequential lithium/pilocarpine administration, and (5) the epilepsy-Amio group. The model group expressed a typical clinical picture of epileptiform activity confirmed by the augmented electroencephalogram alpha and beta spikes. The anticonvulsive effect of amiodarone was prominent, it diminished (p < 0.001) the severity of seizures and hence, deaths and reduced serum noradrenaline levels. In the model group, the electrocardiogram findings revealed tachycardia, prolongation of the corrected QT (QTc) interval, depressed ST segments and increased myocardial oxidative stress. The in-vitro myocardial performance (contraction force and - (df/dt)_max ) was also reduced. Amiodarone decreased (p < 0.001) the heart rate, improved ST segment depression, and myocardial contractility with no significant change in the duration of the QTc interval. Amiodarone preserved the cardiac histological structure and reduced the myocardial injury markers represented by serum Troponin-I, oxidative stress and IL-1. Amiodarone pretreatment prevented the anticipated cardiac injury induced during epilepsy. Amiodarone possessed an anticonvulsive potential, protected the cardiac muscle and preserved its histological architecture. Therefore, amiodarone could be recommended as a protective therapy against cardiac dysfunction during epileptic seizures with favourable effect on seizure activity.

Amiodarone in the COVID-19 Era: Treatment for Symptomatic Patients Only, or Drug to Prevent Infection?

Amiodarone, one of the most widely prescribed antiarrhythmic drugs to treat both ventricular and supraventricular arrhythmias, has been identified as a candidate drug for use against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We present the rationale of using amiodarone in the COVID-19 scenario, as well as whether or not amiodarone administration represents a potential strategy to prevent SARS-CoV-2 infection, rather than simply used to treat patients already symptomatic and/or with severe coronavirus disease 2019 (COVID-19), based on current evidence.

Effectiveness of amiodarone in treatment of cutaneous leishmaniasis caused by Leishmania major

Development of new chemotherapeutic agents is an essential issue in the treatment and control of a disease. This study aimed to evaluate the anti-leishmanial activity of amiodarone, an antiarrhythmic class III drug, against Leishmania major, the most prevalent etiological agent of cutaneous leishmaniasis in the old world. The proliferation of promastigotes and intracellular amastigotes in the absence or presence of amiodarone was estimated, in an in vitro study. For in vivo study, five weeks after infection of BALB/c mice with L. major, when the lesions appeared at the injection site, the mice were divided into four groups (n = 6 each); treatment was conducted for 28 consecutive days with vehicle, amiodarone at 40 mg/kg orally and glucantime at 60 mg/kg intraperitoneally. Therapy with amiodarone reduced the size of lesions compared to the untreated group after 12 days. Amiodarone decreased the parasite load and inflammatory responses, particularly the macrophages containing amastigotes, and enhanced granulation tissue formation in the dermis and subcutaneous area. The Tumor necrosis factor-α and Interleukin-6 levels were significantly lower in the cell culture supernatants of the inguinal lymph node in the amiodarone treated group compared to the vehicle and untreated groups. Amiodarone significantly increased the activity of glutathione peroxidase in comparison to the vehicle and untreated groups but did not affect the plasma levels of superoxide dismutase, malondialdehyde, adiponectin, and ferric reducing ability of plasma. Therefore, the anti- L. major activity and immunomodulatory effects of amiodarone reduced the parasitic load and enhanced wound healing in cutaneous leishmaniasis in BALB/c mice. Amiodarone reduced the lesion surface area, but it did not cure it completely.

NFkappaB is a Key Player in the Crosstalk between Inflammation and Cardiovascular Diseases

Inflammation is a key mechanism of cardiovascular diseases. It is an essential component of atherosclerosis and a significant risk factor for the development of cardiovascular events. In the crosstalk between inflammation and cardiovascular diseases, the transcription factor NFκB seems to be a key player since it is involved in the development and progression of both inflammation and cardiac and vascular damage. In this review, we deal with the recent findings of the role of inflammation in cardiac diseases, focusing, in particular, on NFκB as a functional link. We describe strategies for the therapeutic targeting of NFκB as a potential strategy for the failing heart.

Administration of amiodarone during resuscitation is associated with higher tumor necrosis factor-α levels in the early postarrest period in the swine model of ischemic ventricular fibrillation

To compare the early postarrest inflammatory cytokine response between animals administered amiodarone (AMIO) and lidocaine (LIDO) intra-arrest during resuscitation from ventricular fibrillation (VF). Domestic swine (n=32) were placed under general anesthesia and instrumented before spontaneous VF was induced by balloon occlusion of the left anterior descending coronary artery. After 7 min of VF, standard ACLS resuscitation was performed and animals were randomized to either bolus AMIO (5 mg/kg, n=13) or LIDO (1 mg/kg, n=14) for recurrent or refractory VF. A non-antiarrhythmic (n=5) was also used for comparison. Following return of spontaneous circulation (ROSC), tumor necrosis factor (TNF)-α levels were drawn at 30 and 60 min. Groups were comparable with respect to prearrest hemodynamics and resuscitation variables. In the postarrest period, the LIDO and non-antiarrhythmic group demonstrated virtually identical TNF-α response trajectories. However, TNF-α levels were significantly higher in AMIO- than LIDO-treated animals at 30 min (geometric mean 539 versus 240 pg/mL, 2.2-fold higher, 95% confidence interval [CI] 1.3-3.8-fold higher, P=0.003) and at 60 min (geometric mean 570 versus 204 pg/mL, 2.8-fold higher, 95% CI 1.1-7.0-fold higher, P=0.03). Significant differences in the postarrest TNF-α levels were observed between animals treated with AMIO as compared to those treated with LIDO. Improved rates of ROSC seen with AMIO may come at the expense of a heightened proinflammatory state in the postcardiac arrest period.

Amiodarone impairs trafficking through late endosomes inducing a Niemann-Pick C-like phenotype

Patients treated with amiodarone accumulate lysobisphosphatidic acid (LBPA), also known as bis(monoacylglycero)phosphate, in airway secretions and develop in different tissues vacuoles and inclusion bodies thought to originate from endosomes. To clarify the origin of these changes, we studied in vitro the effects of amiodarone on endosomal activities like transferrin recycling, Shiga toxin processing, ESCRT-dependent lentivirus budding, fluid phase endocytosis, proteolysis and exosome secretion. Furthermore, since the accumulation of LBPA might point to a broader disturbance in lipid homeostasis, we studied the effect of amiodarone on the distribution of LBPA, unesterified cholesterol, sphingomyelin and glycosphyngolipids. Amiodarone analogues were also studied, including the recently developed derivative dronedarone. We found that amiodarone does not affect early endosomal activities, like transferrin recycling, Shiga toxin processing and lentivirus budding. Amiodarone, instead, interferes with late compartments of the endocytic pathway, blocking the progression of fluid phase endocytosis and causing fusion of organelles, collapse of lumenal structures, accumulation of undegraded substrates and amassing of different types of lipids. Not all late endocytic compartments are affected, since exosome secretion is spared. These changes recall the Niemann-Pick type-C phenotype (NPC), but originate by a different mechanism, since, differently from NPC, they are not alleviated by cholesterol removal. Studies with analogues indicate that basic pKa and high water-solubility at acidic pH are crucial requirements for the interference with late endosomes/lysosomes and that, in this respect, dronedarone is at least as potent as amiodarone. These findings may have relevance in fields unrelated to rhythm control.

Role of the cholinergic antiinflammatory pathway in murine autoimmune myocarditis

RATIONALE

This study was performed to gain insights into novel therapeutic approaches for the treatment of autoimmune myocarditis.

OBJECTIVE

Chemical stimulation of the efferent arm of the vagus nerve through activation of nicotinic acetylcholine receptor subtype-7α (α7-nAChR) has been shown to be protective in several models of inflammatory diseases. In the present study, we investigated the potentially protective effect of vagus nerve stimulation on myocarditis.

METHODS AND RESULTS

A/J mice were immunized with cardiac troponin I (TnI) to induce autoimmune myocarditis. Mice were exposed to drinking water that contained nicotine in different concentrations and for different time periods (for 3 days at 12.5 mg/L; 3 days at 125 mg/L; 21 days at 12.5 mg/L; and 21 days at 125 mg/L after first immunization). TnI-immunized mice with no pharmacological treatment showed extensive myocardial inflammation and fibrosis and significantly elevated levels of interleukin-6 and tumor necrosis factor-α. Furthermore, elevated levels of mRNA transcripts of proinflammatory chemokines (monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and RANTES) and chemokine receptors (CCR1, CCR2, and CCR5) were found. Oral nicotine administration reduced inflammation within the myocardium, decreased the production of interleukin-6 and tumor necrosis factor-α, and downregulated the expression of monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, RANTES, CCR1, CCR2, and CCR5. In addition, nicotine treatment resulted in decreased expression of matrix metalloproteinase-14, natriuretic peptide precursor B, tissue inhibitor of metalloproteinase-1, and osteopontin, proteins that are commonly involved in heart failure. Finally, we found that nicotine reduced levels of pSTAT3 (phosphorylated signal transducer and activator of transcription 3) protein expression within the myocardium. Neostigmine treatment did not affect the progression of myocarditis.

CONCLUSIONS

We showed that activation of the cholinergic antiinflammatory pathway with nicotine reduces inflammation in autoimmune myocarditis. Our results may open new possibilities in the therapeutic management of autoimmune myocarditis.

Short-term amiodarone treatment attenuates the production of monocyte cytokines and chemokines by C-reactive protein and improves cardiac function in patients with idiopathic dilated cardiomyopathy and ventricular tachycardia

BACKGROUND

Increased expression of cytokines and chemokines has been observed in chronic heart failure (CHF). Amiodarone reduces circulating cytokine levels, so it may attenuate the production of monocyte cytokines and chemokines by C-reactive protein (CRP) and thus improve the left ventricular ejection fraction (LVEF) in dilated cardiomyopathy (DCM) patients with ventricular tachycardia (VT).

METHODS AND RESULTS

Peripheral blood mononuclear cells (PBMCs) were stimulated by 25 microg/ml CRP in 23 patients with DCM, who were divided into 2 groups based on whether or not amiodarone was included in their treatment (Amiodarone group n=8; No amiodarone group n=15). Tumor necrosis factor (TNF)-alpha and monocyte chemoattractant protein (MCP)-1 on monocytes at baseline and after 4 weeks of treatment was measured by ELISA and expressed as mean+/-SD (pg.ml(-1)x10(-6) PBMCs). The LVEF and the CRP-induced monocyte cytokine and chemokine production were unchanged in the No amiodarone group after 4 weeks; however, LVEF in the Amiodarone group was increased (32.7+/-6.9 to 39.2+/-6.9%; P=0.005), and TNF-alpha and MCP-1 production in the Amiodarone group were decreased (P=0.012, respectively).

CONCLUSIONS

Amiodarone attenuates the production of monocyte cytokines and chemokines by CRP, and improves LVEF in CHF patients with VT.

Involvement of thymus in amiodarone-treated autoimmune myocarditis in rats

We previously showed that amiodarone, an iodine-rich benzofuranic derivative, interferes with the progression of myocarditis using a rat model of experimental autoimmune myocarditis. Further studies have also revealed that intraperitoneal treatment with 12.5 mg/kg amiodarone, which is below the range of its therapeutic plasma concentration, also effectively interferes with the progression of myocarditis using the same model. The relationship between myocarditis and the thymus has not been studied in either patients or animal models. To investigate whether the thymus is involved in the effect of amiodarone on experimental autoimmune myocarditis, we examined its phenotypic distribution in thymocytes and peripheral blood lymphocytes using flow cytometry. We found no significant differences in the proportions of CD4(+) and CD8(+) T cells and the CD4(+)/CD8(+) T cell ratio in the control group compared with amiodarone-treated group. However, amiodarone-treated group induced a decrease in the proportion of CD4(+)TNF(+) and CD4(+)IL-4(+) T cells and an increase in CD4(+)IFN(+) T cells, resulting in a significant reduction of the CD4(+)TNF(+)/CD4(+)IFN(+) and CD4(+)IL-4(+)/CD4(+)IFN(+) T cell ratios. These results suggest for the first time that the thymus is actively involved when myocarditis is treated with amiodarone.

Interleukin-2 serum levels variations in recent onset atrial fibrillation are related with cardioversion outcome

We evaluated the hypothesis that a relationship exists between inflammation and the outcome of pharmaceutical cardioversion with amiodarone in recent onset atrial fibrillation. We studied 86 patients with symptomatic recent onset AF and coexisting hypertension and/or chronic stable coronary artery disease. All study participants underwent evaluation with a standardized protocol including echocardiography, cytokine level measurement [interleukin-2 (IL-2), interleukin-6 (IL-6) and high sensitivity C reactive protein (hsCRP)] on admission and at 48h, and administration of intravenous amiodarone. By 48h, 70 patients cardioverted to sinus rhythm. Median serum IL-2 levels on admission were higher in non-cardioverted compared to cardioverted patients (P=0.002). At 48h, non-cardioverted had significantly higher IL-6 (P=0.005) and hsCRP values (P=0.001) compared to cardioverted. Multivariate logistic regression analysis showed that lower IL-2 admission levels were a powerful independent predictor for successful cardioversion (OR: 0.154, 95% CI: 0.043-0.552, P=0.004). In patients with hypertension and/or chronic stable coronary artery disease and symptomatic recent onset AF, low serum IL-2 levels on admission are associated with successful cardioversion with amiodarone. This observation highlights the role of inflammation in AF and might have further prognostic and therapeutic implications.

Emerging treatments for viral myocarditis

Although viral myocarditis has been mostly attributed to enterovirus and adenovirus infection, the importance of hepatitis C virus has recently been noted. Clinical trials of antiviral agents, such as interferons, are in progress, while new therapies such as viral vaccines, recombinant virus and virus receptors, are in preclinical development. Whereas immunosuppression with corticosteroids or cyclosporin is ineffective, immunosuppressors that do not promote viral replication, such as FTY720, and immunomodulation by interleukin-10, are promising new approaches. Inhibition of nuclear factor-κB, angiotensin II and endothelin effectively suppresses inflammation in experimental viral myocarditis. Embryonic stem cell therapy has been demonstrated to be beneficial; however, this requires further investigation.

Amiodarone improves cardiac sympathetic nerve function to hold norepinephrine in the heart, prevents left ventricular remodeling, and improves cardiac function in rat dilated cardiomyopathy

BACKGROUND

It is unclear how amiodarone therapy exerts its effects on left ventricular remodeling and cardiac sympathetic nerve function in chronic heart failure. We investigated long-term effects of amiodarone on rat dilated cardiomyopathy after healing of cardiac myosin-induced autoimmune myocarditis.

METHODS AND RESULTS

Rats were treated with oral amiodarone or vehicle for 6 weeks. We determined cardiac function, left ventricular remodeling, and cardiac sympathetic nerve function with iodine-125-labeled metaiodobenzylguanidine ([I125]MIBG). Amiodarone treatment improved left ventricular pressure, central venous pressure, and rate of isovolumetric contraction and decreased ventricular weight (P<0.005). Expression of cytokine mRNA was unchanged; expression of atrial natriuretic peptide, collagen III, and transforming growth factor-beta1 mRNA was decreased in amiodarone-treated rats (P<0.05). Phenotype of myosin heavy chain was moved toward that of normal rats by amiodarone. Initial myocardial uptake of MIBG decreased by 67% (P<0.001) and washout rate accelerated by 221% in rats with chronic heart failure compared with normal rats. Whereas amiodarone decreased the initial uptake by 71% in normal rats, amiodarone decelerated the early washout and the late washout and improved the late myocardial distribution of MIBG in rats with chronic heart failure (257% compared with vehicle-treated rats with chronic heart failure; P<0.01). In proportion to MIBG distributions, cardiac tissue catecholamines were increased by amiodarone treatment.

CONCLUSIONS

Long-term amiodarone treatment prevented left ventricular remodeling and improved cardiac function in rat dilated cardiomyopathy. Long-term amiodarone treatment also restored cardiac sympathetic tone to hold norepinephrine in the heart.

Anti-inflammatory therapy for heart failure

Recently, inflammation has been shown to be an important aspect of cardiovascular diseases, and markers of inflammation predict risk of adverse cardiovascular events. Accumulating evidence shows that heart failure is an inflammatory disease, and anti-inflammatory therapy by various agents would be a promising future treatment for heart failure.

Amiodarone Decreases Heat, Cold, and Mechanical Hyperalgesia in a Rat Model of Neuropathic Pain

Lidocaine is effective in controlling ventricular dysrhythmia and neuropathic pain. Amiodarone, like lidocaine, has sodium channel blocking properties. In the present study we explore whether amiodarone has a similar effect as lidocaine on the heat, cold, and mechanical hyperalgesia seen in the rat model of neuropathic pain. Ten male Sprague-Dawley rats were anesthetized. Four loose ligatures were placed on the sciatic nerve of the right hindpaw. A sham operation was performed on the contralateral hindpaw (control). Heat hyperalgesia was determined by comparing each paw withdrawal latency to heat stimulation (radiant heat source, 50 degrees C). Cold hyperalgesia was assessed with acetone application. Mechanical hyperalgesia was determined by comparing the mechanical threshold in the ligated and control hind paws using calibrated von Frey filaments. Amiodarone was intraperitoneally administered at doses of 1, 5, 10, 20, 50, and 100 mg/kg after the development of hyperalgesia. The animals were tested for hyperalgesia before and 1, 3, and 24 h after the administration of a single dose of amiodarone. Intrathecal catheters were implanted in 5 new rats, and amiodarone 5 mg/kg was injected. Testing for heat, mechanical, and cold hyperalgesia was performed similarly in the intrathecal amiodarone administration group. Amiodarone produces statistically significant decreases of heat, cold, and mechanical hyperalgesia after intraperitoneal administration. Results are statistically significant at 10 mg/kg (heat hyperalgesia), 20 mg/kg (mechanical hyperalgesia), and 100 mg/kg (cold hyperalgesia) intraperitoneally. Hyperalgesia returns 24 h after a dose. The intrathecal administration of amiodarone produces a nonstatistically significant reduction of hyperalgesia. Amiodarone seems to have a similar effect as lidocaine on the hyperalgesia seen in the rat model of neuropathic pain. As the half-life of amiodarone is significantly longer that that of lidocaine (mean, 53 days versus 90 min) in humans, it may have the potential to provide a longer lasting (and perhaps more effective) effect than lidocaine on neuropathic pain states.

IMPLICATIONS

Amiodarone was found to produce a statistically significant decrease in heat, cold, and mechanical hyperalgesia in a rat model of neuropathic pain after intraperitoneal injection. Considering its long half-life in humans, amiodarone has the potential to provide long lasting pain relief in neuropathic pain states.

Cardioprotective effects of phosphoramidon on myocardial structure and function in murine Chagas' disease

Chagas' disease is an important cause of cardiomyopathy. Endothelin-1, a vasoactive peptide has been implicated in the pathogenesis of chagasic cardiomyopathy. C57BL/6 x 129sv and CD1 mice were thus, infected with trypomastigotes of Trypanosoma cruzi (Brazil strain) and these infected mice were compared with infected mice treated with phosphoramidon. This compound inhibits endothelin-converting enzyme and neutral endopeptidases and does not affect the growth of the parasite in culture. Phosphoramidon was given in a dose of 10mg/kg for the initial 15 days post-infection None of the C57Bl/6 x 129sv mice died as a result of infection. However, there was marked myocardial inflammation and fibrosis in infected, untreated mice. The hearts of the infected, phosphoramidon-treated mice showed significantly less pathology. Cardiac magnetic resonance imaging of infected mice revealed right ventricular dilation that was less severe in those treated with phosphoramidon. Phosphoramidon-treated CD1 mice survived the acute infection. Transthoracic echocardiography demonstrated left ventricular dilation and reduced percent fractional shortening and relative wall thickness. These alterations were also attenuated as a result of phosphoramidon treatment. These data suggest that endothelin-1 contributes to the pathogenesis of chagasic cardiomyopathy and interventions that inhibit the synthesis of endothelin-1 and/or neutral endopeptidase might have a protective effect on myocardial structure and function in murine Chagas' disease.