Current Pharmaceutical Design - Volume 17, Issue 33, 2011

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Over the last few years, the implication of the (pro)renin receptor [(P)RR] in the pathogenesis of end-organ damage has been shown through many different studies. The (P)RR plays a dual role when stimulated by renin or prorenin as it enhances both cell surface production of angiotensin and stimulates angiotensin-independent intracellular signaling cascades. Since Ichihara's group demonstrated activation of prorenin when it was bound to antibodies targeted against a specific region in the renin prosegment, they designed a complementary decapeptide to this region called the handle region to use as a potential (P)RR blocker (PRRB). The effects of systemic administration of the PRRB on the development and progression of different renal, cardiac and ocular pathologies have been observed and have thus proposed the blocker as a potential new treatment for these afflictions. Conversely, the specificity of the PRRB has been questioned as conflicting results have been reported in the literature. A recent study has described a new high affinity binding site for renin and prorenin to the (P)RR called the hinge region. Hence, although there is great promise in the (P)RR potential as a therapeutic target, still much research is required to better identify adequate blockers.

Cholelithiasis is a common disease worldwide. The majority of gallstones can occur when the bile is supersaturated with cholesterol. Dyslipidaemia, obesity, insulin resistance are associated with an increased risk for cholesterol gallstone formation as well as with vascular risk. Statins and ezetimibe are used to treat dyslipidaemia and appear to have some effect on bile composition and cholesterol gallstone formation. Statin (e.g. pravastatin, simvastatin, fluvastatin and lovastatin) monotherapy or combined with ursodeoxycholic acid (UDCA) have shown reductions in bile cholesterol saturation, preventing gallstone formation and even dissolving pre-existing stones. However, this effect was not consistently reported in all studies. Statin use has also been associated with a reduced risk for cholecystectomy in 2 large epidemiological studies. Ezetimibe was shown to have a beneficial action against cholelithiasis in animal studies but data in humans - although promising - are very limited. The effect of these drugs on gallstone disease warrants further investigation in large human trials. We also consider the links between cholelithiasis, vascular risk and the use of lipid lowering drugs.

Several cross-sectional studies have reported a relationship between elevated serum activity of liver enzymes [e.g. alanine aminotransferase (ALT) and gamma-glutamyltransferase (γGT)] and metabolic syndrome (MetS) and/or diabetes mellitus (DM). Raised serum activity of liver enzymes independently predicted the future development of MetS and DM as well as cardiovascular (CV) events and/or total/CV mortality in prospective studies. However, this association was not consistently demonstrated and it appears to be independent of alcohol intake. Even though these associations can be partly attributed to non-alcoholic fatty liver disease (NAFLD) and insulin resistance, there may be additional underlying mechanisms that contribute to the increased CV risk (e.g. inflammation and oxidative stress). The association of γGT with atherosclerotic plaque is of particular importance. The present review considers the link between serum liver enzyme activities and vascular risk. The links with DM and MetS are also discussed.

Normal aerobic metabolism is associated with reactive oxygen species (ROS) that can damage cellular macromolecules. Analogous free radicals are formed by exposure to ionizing radiation and many dietary products are considered to contain free radical generators. During the past 15 years epidemiological studies and animal experiments have identified bilirubin as a molecule at the crossroads of the protection of the body against ROS. The studies have focused on bilirubin as a biomarker of arterial disease. This review assesses the current state of evidence and sets the data in context. There is no definitive evidence from prospective studies of a causal protective effect from bilirubin in arterial disease or that various genetic polymorphisms, (particularly the 7/7 UGT1A1 repeat polymorphism) impacts coronary artery disease. There is no definitive evidence that high bilirubin levels confer protection against cancer. There is some preliminary evidence that bilirubin may have a protective effect in lung disease and stroke, but the reports have yet to be confirmed. The role of various genotypes of UGT1A1 and HMOX1, if any, in cancer is unclear.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a calcium-independent phospholipase A2 that circulates in plasma in association with lipoprotein particles, whereas in atherosclerotic plaques it is co-localized with macrophages. Lp-PLA2 generates two proinflammatory mediators, lysophosphatidylcholine and oxidized nonesterified fatty acids, which play a role in the development of atherosclerotic lesions and formation of a necrotic core, leading to more vulnerable plaques. Epidemiologic studies demonstrate that increased circulating levels of Lp-PLA2 predict an increased risk of myocardial infarction, stroke and cardiovascular mortality. Furthermore, histologic examination of diseased human coronary arteries reveals intense presence of the enzyme in atherosclerotic plaques that are prone to rupture. These considerations suggest Lp-PLA2 as a promising therapeutic target in cardiovascular disease. Plasma levels of Lp-PLA2 are increased in various types of hyperlipidemias, while hypolipidemic drugs reduce plasma Lp-PLA2 activity and mass along with the improvement of plasma lipid profile. A selective inhibitor of Lp-PLA2 activity, darapladib, has been developed and studies in animal models and humans have shown that it effectively and safely reduces Lp-PLA2 activity in plasma and in atherosclerotic plaques. Furthermore, in animal models darapladib decreases plaque area and necrotic core area whereas in humans it prevents the expansion of necrotic core volume. Whether the results obtained from the use of darapladib in studies in vitro, as well as in preclinical and clinical studies would translate into benefits on cardiovascular event outcomes, awaits to be proved in 2 ongoing phase 3 trials.

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. There is growing evidence that molecular chaperones, many of which are heat shock proteins HSPs, are involved in CVD pathogenesis. In this review we focus on HSP60, the human mitochondrial chaperone that also displays extramitochondrial and extracellular functions. HSP60 is typically cytoprotective but a number of stress conditions determine its conversion to a potentially toxic molecule for cells and tissues. We present illustrative examples of specific subtypes of CVD where HSP60 is implicated in the initiation and/or progression of disease. The data not only indicate a pathogenic role for HSP60 but also its potential as a biomarker with applications for diagnosis, assessing prognosis and response to treatment, as well as for preventing and treating CVD.

Hypercholesterolemia is a major risk factor for cardiovascular disease (CVD), the leading cause of death worldwide. Since the late 1980s, statins have emerged as effective lipid-lowering therapies and are now widely used to protect against and slow the progression of CVD and cerebrovascular disease. However, there is a significant gap between disease improvement in clinical trials and daily practice possibly attributable to poor adherence with statin therapy. High discontinuation rates were reported in primary and secondary prevention. This systematic review aims to summarize the current literature regarding the association between statin therapy discontinuation and cardiovascular and cerebrovascular events and all-cause mortality in high-risk patients. Available English literature was reviewed using Medline, Embase, Web of Sciences and the Cochrane Library; 39 studies were identified. In primary and secondary prevention, as well as perioperatively, non-adherence or discontinuation of statin therapy was associated with detrimental effects on cardiovascular and cerebrovascular outcomes, including disease severity and mortality. Importantly, some studies reported that very low adherence and discontinuation was associated with worse outcomes than never using statins. In conclusion, non-adherence and discontinuation of statin therapy significantly increased the incidence of cardiovascular and cerebrovascular events as well as all-cause mortality in high-risk patients. Patients would therefore benefit from closer adherence assessment and education programs aimed at increasing awareness of the risk associated with discontinuation of statin therapy.

Evidence suggests that patient gender is associated with the quality of care provided in the treatment of cardiometabolic diseases. The majority of findings suggest that female patients receive less intensified care than male patients. However, the question whether physician gender plays a role in the quality of care has been debated for some time. For example, it has been postulated that the practice styles of female physicians, such as spending more time with a patient, hearing and listening more effectively, and including more preventive measures, may result in more efficient clinical encounters that may positively affect clinical outcomes. This narrative review examines the existing evidence regarding the effects of physician gender on the quality of care provided, focusing mainly on patients with cardiometabolic diseases.

The metabolic syndrome (MetS) is common, and its associated risk burdens of diabetes and cardiovascular disease (CVD) are a major public health problem. The hypothesis that main constituent parameters of the MetS share common pathophysiologic mechanisms provides a conceptual framework for the future research. Exercise and weight loss can prevent insulin resistance and reduce the risk of diseases associated with the MetS. Interrupting intracellular and extracellular reactive oxygen species (ROS) overproduction could also contribute to normalizing the activation of metabolic pathways leading to the onset of diabetes, endothelial dysfunction, and cardiovascular (CV) complications. On the other hand, it is difficult to counteract the development of CV complications by using conventional antioxidants. Indeed, interest has focused on strategies that enhance the removal of ROS using either antioxidants or drugs that enhance endogenous antioxidant defense. Although these strategies have been effective in laboratory experiments, several clinical trials have shown that they do not reduce CV events, and in some cases antioxidants have actually worsened the outcome. More research is needed in this field.

Protein-protein and protein-nucleic acid interactions are involved in many regulatory cellular pathways, playing a key role in cell growth and proliferation, as well as in the progression and development of various diseases such as infectious diseases. Especially in the anti-AIDS research, protein-protein and protein-nucleic acid complexes are being considered as promising targets for pharmaceutical interventions aimed at overcoming the drug resistance observed for most of the classic enzyme inhibitors. Consequently, more and more protein-protein and protein-nucleic acid interaction inhibitors have being identified and developed as candidate agents for antiretroviral therapy. Here, we review the state of the art in the discovery and development of protein-protein and protein-nucleic acid interaction inhibitors that block the main steps of the HIV-1 replication cycle, giving a medicinal chemistry-oriented view of strategies for inhibiting these regulatory interactions that are involved in the entry process, in the dimerization of reverse transcriptase and protease enzymes, and in the activity of the nucleocapsid protein by means of small molecular potential therapeutic agents.

The blood-brain barrier (BBB) provides a vast interface for cytokines to affect CNS function. The BBB is a target for therapeutic intervention. It is essential, therefore, to understand how cytokines interact with each other at the level of the BBB and how secondary signals modulate CNS functions beyond the BBB. The interactions between cytokines and lipids, however, have not been fully addressed at the level of the BBB. Here, we summarize current understanding of the localization of cytokine receptors and transporters in specific membrane microdomains, particularly lipid rafts, on the luminal (apical) surface of the microvascular endothelial cells composing the BBB. We then illustrate the clinical context of cytokine effects on the BBB by neuroendocrine regulation and amplification of inflammatory signals. Two unusual aspects discussed are signaling crosstalk by different classes of cytokines and genetic regulation of drug efflux transporters. We also introduce a novel area of focus on how cytokines may act through nuclear hormone receptors to modulate efflux transporters and other targets. A specific example discussed is the ATP-binding cassette transporter-1 (ABCA-1) that regulates lipid metabolism. Overall, cytokine signaling at the level of the BBB is a crucial feature of the dynamic regulation that can rapidly change BBB function and affect brain health and disease.