Effects of statins on liver cell function and inflammation in septic rats

Early Diagnosis and Prevention of Infections in Cirrhosis

Strategies to prevent infection and improve outcomes in patients with cirrhosis. HAV, hepatitis A virus; HBV, hepatitis B virus; COVID-19, novel coronavirus disease 2019; NSBB, nonselective β-blocker; PPI, proton pump inhibitors.Cirrhosis is a risk factor for infections. Majority of hospital admissions in patients with cirrhosis are due to infections. Sepsis is an immunological response to an infectious process that leads to end-organ dysfunction and death. Preventing infections may avoid the downstream complications, and early diagnosis of infections may improve the outcomes. In this review, we discuss the pathogenesis, diagnosis, and biomarkers of infection; the incremental preventive strategies for infections and sepsi; and the consequent organ failures in cirrhosis. Strategies for primary prevention include reducing gut translocation by selective intestinal decontamination, avoiding unnecessary proton pump inhibitors' use, appropriate use of β-blockers, and vaccinations for viral diseases including novel coronavirus disease 2019. Secondary prevention includes early diagnosis and a timely and judicious use of antibiotics to prevent organ dysfunction. Organ failure support constitutes tertiary intervention in cirrhosis. In conclusion, infections in cirrhosis are potentially preventable with appropriate care strategies to then enable improved outcomes.

Cirrhosis as new indication for statins

In the recent years, there have been an increasing number of reports on favourable effects of statins in patients with advanced chronic liver disease. These include reduction in portal pressure, improved liver sinusoidal endothelial and hepatic microvascular dysfunction, decreased fibrogenesis, protection against ischaemia/reperfusion injury, safe prolongation of ex vivo liver graft preservation, reduced sensitivity to endotoxin-mediated liver damage, protection from acute-on-chronic liver failure, prevention of liver injury following hypovolaemic shock and preventing/delaying progression of cirrhosis of any aetiology. Moreover, statins have been shown to have potential beneficial effects in the progression of other liver diseases, such as chronic sclerosing cholangitis and in preventing hepatocellular carcinoma. Because of these many theoretically favourable effects, statins have evolved from being considered a risk to kind of wonder drugs for patients with chronic liver diseases. The present article reviews the current knowledge on the potential applications of statins in chronic liver diseases, from its mechanistic background to objective evidence from clinical studies.

Mitophagy is required for acute cardioprotection by simvastatin

AIMS

We have shown that autophagy and mitophagy are required for preconditioning. While statin's cardioprotective effects are well known, the role of autophagy/mitophagy in statin-mediated cardioprotection is not. In this study, we used HL-1 cardiomyocytes and mice subjected to ischemia/reperfusion to elucidate the mechanism of statin-mediated cardioprotection.

RESULTS

HL-1 cardiomyocytes exposed to simvastatin for 24 h exhibited diminished protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling, increased activation of unc-51-like kinase 1, and upregulation of autophagy and mitophagy. Similar findings were obtained in hearts of mice given simvastatin. Mevalonate abolished simvastatin's effects on Akt/mTOR signaling and autophagy induction in HL-1 cells, indicating that the effects are mediated through inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. Simvastatin-treated HL-1 cells exhibited mitochondrial translocation of Parkin and p62/SQSTM1, fission, and mitophagy. Because Parkin is required for mitophagy and is expressed in heart, we investigated the effect of simvastatin on infarct size in Parkin knockout mice. Simvastatin reduced infarct size in wild-type mice but showed no benefit in Parkin knockout mice. Inhibition of HMG-CoA reductase limits mevalonate availability for both cholesterol and coenzyme Q10 (CoQ) biosynthesis. CoQ supplementation had no effect on statin-induced Akt/mTOR dephosphorylation or macroautophagy in HL-1 cells, but it potently blocked mitophagy. Importantly, CoQ supplementation abolished statin-mediated cardioprotection in vivo.

INNOVATION AND CONCLUSION

Acute simvastatin treatment suppresses mTOR signaling and triggers Parkin-dependent mitophagy, the latter which is required for cardioprotection. Coadministration of CoQ with simvastatin impairs mitophagy and cardioprotection. These results raise the concern that CoQ may interfere with anti-ischemic benefits of statins mediated through stimulation of mitophagy.

Statins, fibrates, thiazolidinediones and resveratrol as adjunctive therapies in sepsis: could mitochondria be a common target?

Through their pleiotropic actions, statins, fibrates, thiazolidinediones and resveratrol can target multiple mechanisms involved in sepsis. Their actions on mitochondrial function are of interest in a pathological state where bioenergetic failure may play a key role in the development of organ dysfunction. We review these four drug groups as potential adjunctive therapies in sepsis with a particular focus upon mitochondria. Systematic review of clinical and experimental trials was done with a literature search using the PubMed database. Search terms included statins, fibrates, thiazolidinediones, resveratrol, mitochondria, sepsis, peroxisome proliferator-activated receptors, inflammation, oxidative stress and organ dysfunction. With the exception of statins, most of the compelling evidence for the use of these agents in sepsis comes from the experimental literature. The agents all exert anti-inflammatory and anti-oxidant properties, plus protective effects against mitochondrial dysfunction and stimulation of mitochondrial biogenesis. Improved outcomes (organ dysfunction, survival) have been reported in a variety of sepsis models. Notably, positive outcome effects were more commonly seen when the agents were given as pre- rather than post-treatment of sepsis. Statins, fibrates, thiazolidinediones and resveratrol prevent sepsis-induced injury to organs and organelles with outcome improvements. Their effects on mitochondrial function may be integral in offering this protection. Definitive clinical trials are needed to evaluate their utility in septic patients or those at high risk of developing sepsis.

Atorvastatin inhibits the expression of RAGE induced by advanced glycation end products on aortas in healthy Sprague-Dawley rats

BACKGROUND

Atorvastatin can downregulate the expression of receptor for advanced glycation end products (RAGE) in the aortas of diabetic rats. However, its effect on healthy rats remains unclear. The aim of this study was to observe the direct impact of atorvastatin on advanced glycation end products- (AGEs) induced RAGE expression in healthy Sprague Dawley (SD) rats.

METHODS

SD rats received AGE-BSA (20 mg/kg/day or 40 mg/kg/day), dual treatment (AGE-BSA 40 mg/kg/day and atorvastatin 20 mg/kg/day) or no treatment for 12 and 24 weeks, respectively. The deposition of AGEs and expression of RAGE in the animals' aortas were assessed by Quantitative RT-PCR, immunohistochemistry, and western-blot tests. Serum levels of AGEs were measured using ELISA.

RESULTS

AGE-BSA upregulated the serum level of AGEs, deposition of AGEs, and expression of RAGE in aortas in a time- and dose-dependent way that can accelerate the development and progression of atherosclerosis. These upregulations could be significantly attenuated by atorvastatin in the absence of its lipid-lowering effects. These data provide further evidence for the novo mechanism of atorvastatin's pleiotropic effect.

CONCLUSION

Atorvastatin has a direct inhibitory effect on AGEs-RAGE expression in healthy SD rats. These potential pleiotropic vasculoprotective effects are independent of effects on glucose and lipid control.