Contribution of mammalian target of rapamycin in the pathophysiology of cirrhotic cardiomyopathy

Self-eating and Heart: The Emerging Roles of Autophagy in Calcific Aortic Valve Disease

Autophagy is a self-degradative pathway by which subcellular elements are broken down intracellularly to maintain cellular homeostasis. Cardiac autophagy commonly decreases with aging and is accompanied by the accumulation of misfolded proteins and dysfunctional organelles, which are undesirable to the cell. Reduction of autophagy over time leads to aging-related cardiac dysfunction and is inversely related to longevity. However, despite the increasing interest in autophagy in cardiac diseases and aging, the process remains an undervalued and disregarded object in calcific valvular disease. Neither the nature through which autophagy is triggered nor the interplay between autophagic machinery and targeted molecules during aortic valve calcification are fully understood. Recently, the upregulation of autophagy has been shown to result in cardioprotective effects against cell death as well as its origin. Here, we review the evidence that shows how autophagy can be both beneficial and detrimental as it pertains to aortic valve calcification in the heart.

Protective Effects of Spermidine Against Cirrhotic Cardiomyopathy in Bile Duct-Ligated Rats

Cirrhotic cardiomyopathy is a critical factor that causes morbidity and mortality in crucial conditions such as liver transplantation. In animal model, the common pathophysiologic mechanisms of cirrhotic cardiomyopathy are similar to those associated with bile duct ligation (BDL). Overproduction of inflammatory and oxidant markers plays a crucial role in cirrhotic cardiomyopathy. Spermidine, a multifunctional polyamine, is known for its antioxidant and anti-inflammatory effects. In this study, we investigated the effects of spermidine on development of cirrhotic cardiomyopathy in BDL rats. Rats were randomly housed in 6 groups. Except the normal and sham groups, BDL was performed for all the control and spermidine groups. Seven days after operation, 3 different doses of spermidine (5, 10 and 50 mg/kg) were administrated until day 28, in spermidine groups. At the end of the fourth week, the electrocardiography (ECG) and papillary muscle isolation were performed. The serum level of tumor necrosis factor-a (TNF-α), interleukin-1β (IL-1β), and IL-10 and cardiac level of superoxide dismutase, glutathione (GSH). and malondialdehyde (MDA) were assessed. Furthermore, the nuclear factor-κB (NF-κB) expression was assessed by western blot. Cardiac histopathological changes were monitored. The serum levels of magnesium (Mg) and potassium (K) were investigated. Control group, exhibited exaggerated signs of cirrhotic cardiomyopathy in comparison with the sham group. Co-administration of spermidine at the dose of 10 mg/kg in BDL rats significantly improved the cardiac condition, reduced the inflammatory mediators, and increased antioxidant enzymes. In addition, the histopathologic findings were in accordance with the other results of the study. Besides, there was no significant alteration in serum levels of Mg and K. This study demonstrates that spermidine at the dose of 10 mg/kg significantly improved the cirrhotic cardiomyopathy in BDL model in rats.

The Role of MicroRNAs in Regulating Cytokines and Growth Factors in Coronary Artery Disease: The Ins and Outs

Coronary artery diseases (CAD), as a leading cause of mortality around the world, has attracted the researchers' attention for years to find out its underlying mechanisms and causes. Among the various key players in the pathogenesis of CAD cytokines, microRNAs (miRNAs) are crucial. In this study, besides providing a comprehensive overview of the involvement of cytokines, growth factors, and miRNAs in CAD, the interplay between miRNA with cytokine or growth factors during the development of CAD is discussed.

The protective potential of metformin against acetaminophen-induced hepatotoxicity in BALB/C mice

CONTEXT

Acetaminophen overdose is regarded to a common cause of acute liver failure. The hepatotoxicity leads to mitochondrial oxidative stress and subsequent necrotic hepatocellular death.

OBJECTIVE

This study examines the protective effect of metformin on acetaminophen-induced oxidative stress, inflammation and subsequent hepatotoxicity in mice.

MATERIALS AND METHODS

Male BALB/c mice were orally administered to acetaminophen (250 mg/kg/d) for a 7-day period. The mice received metformin (100 and 200 mg/kg/d, p.o.) for 21 days. To evaluate acetaminophen-induced oxidative stress, liver tissue level of malodialdehyde (MDA), end product of membrane lipid peroxidation, and activities of superoxide dismutase (SOD) and glutathione (GSH) were measured. Histological analysis and measurement of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were performed. Moreover, tissue concentrations of proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), along with, C-reactive protein (CRP) were assessed.

RESULTS

Acetaminophen caused focal hepatocyte necrosis, inflammation and fatty degeneration, as well as increased tissue levels of AST, ALT, ALP and MDA, and also decreased GSH and SOD activities. Moreover, IL-6, TNF-α and CRP levels were increased following acetaminophen hepatotoxicity. Metformin (200 mg/kg/d) significantly normalized MDA, SOD and GSH levels (p < 0.001), and exerted a hepatoprotective effect by significant decreasing ALT, AST and ALP concentrations (p < 0.001). The tissue levels of IL-6, TNF-α and CRP were markedly decreased by 21-day treatment with metformin (200 mg/kg/d) (p < 0.001).

DISCUSSION

The results suggest metformin protects hepatocytes against acute acetaminophen toxicity. Metformin is indicated to diminish oxidative stress, proinflammatory cytokines, and hepatocyte necrosis.