Selective thyromimetics for atherosclerosis and dyslipidaemia: another old target making progress

Thyroid hormone analogues and derivatives: Actions in fatty liver

Fatty liver or nonalcoholic fatty liver disease (NAFLD), a problem of increasing clinical significance and prevalence worldwide, is associated with increased risk for the development of cirrhosis and hepatocellular carcinoma. Although several therapeutic approaches can be used in the context of NAFLD, dietary and physical activities are still the most frequently used strategies. Some pharmacological agents show promising results although no conclusions can be drawn from recent clinical trials. Thyroid hormones [THs; thyroxine (T4) and 3,3′,5-triiodo-L-thyronine (T3)] coordinate a diverse array of physiological events during development and lipid/energy homeostasis and have some potentially therapeutic actions which include inducing weight loss, and lowering plasma cholesterol levels and tissue adiposity. The thyroid hormones exert their physiological effects by binding to specific nuclear receptors [thyroid hormone receptors (TR)] of which the TRβ isoform is liver specific and has been considered a putative target for the treatment of dyslipidemia and fatty liver. In view of this, the aim of the review is (1) to provide an overview of the action of T3 on lipid metabolism with implications for liver steatosis and (2) to provide an update on the current knowledge concerning the administration of TRβ selective thyromimetics (GC-1 and MB07811), as well as of 3,5-diiodo-L-thyronine and its novel functional analogue TRC150094 in animal models of overweight and related disorders including primarily fatty liver.

Nonalcoholic fatty liver disease: molecular pathways and therapeutic strategies

Along with rising numbers of patients with metabolic syndrome, the prevalence of nonalcoholic fatty liver disease (NAFLD) has increased in proportion with the obesity epidemic. While there are no established treatments for NAFLD, current research is targeting new molecular mechanisms that underlie NAFLD and associated metabolic disorders. This review discusses some of these emerging molecular mechanisms and their therapeutic implications for the treatment of NAFLD. The basic research that has identified potential molecular targets for pharmacotherapy will be outlined.

Novel pharmacotherapies of familial hyperlipidemia

Familial hyperlipidemia is an inherited metabolic disorder characterized by elevated lipid and/or lipoprotein levels in the blood. Despite improvements in lipid-lowering therapy during the last decades, it still remains a substantial contributor to the incidence of cardiovascular disease since patients on current conventional therapies do not achieve their target LDL-cholesterol levels. With a view to lower LDL-cholesterol levels, a number of new therapeutic strategies have been developed over recent years. In this review, we provide an overview of these treatment options that are currently in clinical development and may offer alternative or adjunctive therapies for this high-risk population.

Focus on therapeutic strategies of nonalcoholic Fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the Western world (it affects 30% of the general adult population). The NAFLD encompasses a histological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), defined by steatosis, hepatocellular damage, and lobular inflammation in individuals without significant alcohol consumption and negative viral, congenital, and autoimmune liver disease markers. Currently, NAFLD is considered an emerging epidemic in light of the dramatic increase in obesity rates. With the progressive nature of NASH and its rising prevalence there is a significant need for a specific and targeted treatments since to date there has not been any validated therapies for NAFLD other than weight loss, which is well known to have a poor long-term success rate. In recent years, visceral adipose tissue has taken an important role in NAFLD pathogenesis, and current therapeutic approaches aim at reducing visceral obesity and free fatty acid overflow to the liver. This paper is focused on the treatments used for NAFLD and the potential new therapy.

Emerging molecular targets for the treatment of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic fat accumulation in the absence of significant ethanol consumption, viral infection, or other specific causes of liver disease. Currently the most common chronic liver disease, affecting 30% of the Western world, NAFLD may progress to cirrhosis and end-stage liver disease and may increase the risk of developing diabetes and cardiovascular disease. Although its pathogenesis is unclear, NAFLD is tightly associated with insulin resistance and the metabolic syndrome. No established treatment exists, and current research is targeting new molecular mechanisms that underlie NAFLD and associated cardiometabolic disorders. This review discusses some of these emerging molecular mechanisms and their therapeutic implications for the treatment of NAFLD: microRNAs, incretin analogs/antagonists, liver-specific thyromimetics, AMP-activated protein kinase activators, and nuclear receptors farnesoid X receptor and pregane X receptor.

Structural overview of the nuclear receptor superfamily: insights into physiology and therapeutics

As ligand-regulated transcription factors, the nuclear hormone receptors are nearly ideal drug targets, with internal pockets that bind to hydrophobic, drug-like molecules and well-characterized ligand-induced conformational changes that recruit transcriptional coregulators to promoter elements. Yet, due to the multitude of genes under the control of a single receptor, the major challenge has been the identification of ligands with gene-selective actions, impacting disease outcomes through a narrow subset of target genes and not across their entire gene-regulatory repertoire. Here, we summarize the concepts and work to date underlying the development of steroidal and nonsteroidal receptor ligands, including the use of crystal structures, high-throughput screens, and rational design approaches for finding useful therapeutic molecules. Difficulties in finding selective receptor modulators require a more complete understanding of receptor interdomain communications, posttranslational modifications, and receptor-protein interactions that could be exploited for target gene selectivity.