Darapladib

Cardiolipin in myocardial ischaemia-reperfusion injury: From molecular mechanisms to clinical strategies

Myocardial reperfusion injury occurs when blood flow is restored after ischemia, an essential process to salvage ischemic tissue. However, this phenomenon is intricate, characterized by various harmful effects. Tissue damage in ischemia-reperfusion injury arises from various factors, including the production of reactive oxygen species, the sequestration of proinflammatory immune cells in ischemic tissues, the induction of endoplasmic reticulum stress, and the occurrence of postischemic capillary no-reflow. Secretory phospholipase A2 (sPLA2) plays a crucial role in the eicosanoid pathway by releasing free arachidonic acid from membrane phospholipids' sn-2 position. This liberated arachidonic acid serves as a substrate for various eicosanoid biosynthetic enzymes, including cyclooxygenases, lipoxygenases, and cytochromes P450, ultimately resulting in inflammation and an elevated risk of reperfusion injury. Therefore, the activation of sPLA2 directly correlates with the heightened and accelerated damage observed in myocardial ischemia-reperfusion injury (MIRI). Presently, clinical trials are in progress for medications aimed at sPLA2, presenting promising avenues for intervention. Cardiolipin (CL) plays a crucial role in maintaining mitochondrial function, and its alteration is closely linked to mitochondrial dysfunction observed in MIRI. This paper provides a critical analysis of CL modifications concerning mitochondrial dysfunction in MIRI, along with its associated molecular mechanisms. Additionally, it delves into various pharmacological approaches to prevent or alleviate MIRI, whether by directly targeting mitochondrial CL or through indirect means.

Lipoprotein-associated phospholipase A2: The story continues

Inflammation is thought to play an important role in the pathogenesis of vascular diseases. Lipoprotein-associated phospholipase A2 (Lp-PLA2) mediates vascular inflammation through the regulation of lipid metabolism in blood, thus, it has been extensively investigated to identify its role in vascular inflammation-related diseases, mainly atherosclerosis. Although darapladib, the most advanced Lp-PLA2 inhibitor, failed to meet the primary endpoints of two large phase III trials in atherosclerosis patients cotreated with standard medical care, the research on Lp-PLA2 has not been terminated. Novel pathogenic, epidemiologic, genetic, and crystallographic studies regarding Lp-PLA2 have been reported recently, while novel inhibitors were identified through a fragment-based lead discovery strategy. More strikingly, recent clinical and preclinical studies revealed that Lp-PLA2 inhibition showed promising therapeutic effects in diabetic macular edema and Alzheimer's disease. In this review, we not only summarized the knowledge of Lp-PLA2 established in the past decades but also emphasized new findings in recent years. We hope this review could be valuable for helping researchers acquire a much deeper insight into the nature of Lp-PLA2, identify more potent and selective Lp-PLA2 inhibitors, and discover the potential indications of Lp-PLA2 inhibitors.

Structure, Biosynthesis, and Occurrence of Bacterial Pyrrolizidine Alkaloids

Pyrrolizidine alkaloids (PAs) are widespread plant natural products with potent toxicity and bioactivity. Herein, the identification of bacterial PAs from entomopathogenic bacteria using differential analysis by 2D NMR spectroscopy (DANS) and mass spectrometry is described. Their biosynthesis was elucidated to involve a non-ribosomal peptide synthetase. The occurrence of these biosynthesis gene clusters in Gram-negative and Gram-positive bacteria indicates an important biological function in bacteria.

Health care resource utilization and costs associated with nonfatal major adverse cardiovascular events

BACKGROUND

Risk of recurrent cardiovascular events following an initial cardiovascular-related hospitalization remains high despite available interventions. Rates of cardiovascular events as well as associated health care resource utilization and costs are needed to assess the value of treatments.

OBJECTIVE

To quantify, in patients with previous hospitalization for acute coronary syndrome (ACS), rates of nonfatal major adverse cardiovascular events (MACE) and secondary coronary events (SCE), as well as health care utilization and costs associated with a first MACE.

METHODS

Administrative data from a large population of commercial managed care and managed Medicare enrollees in the United States were retrospectively analyzed. Patients with an ACS-related hospitalization from 2006 to 2011 were followed for 12 months to assess subsequent MACE and SCE rates. Patients were aged ≥ 18 years at initial ACS hospitalization (the index episode) and had ≥ 12 months of continuous health plan enrollment before and after the end of the index episode. Resource utilization and costs during a first MACE were assessed. Multivariable analyses were used to assess the associations between cardiovascular risk factors and the occurrence of a MACE, as well as the costs incurred during a first MACE.

RESULTS

Of 75,231 study patients identified, 3.3% had a MACE and 8.3% had an SCE during the 12-month follow-up. Median time to first MACE and SCE from end of the index episode was 4.6 and 3.7 months, respectively. Mean MACE-related cost incurred during the first MACE was $19,642. Logistic analyses showed that age and diabetes were associated with increased odds of a MACE, while index ACS episodes involving ST-elevation myocardial infarction were associated with reduced odds. Findings from generalized linear models indicated that statin use and age were associated with lower episode-related costs and that MACE occurrence within 3 months of ACS hospitalization was associated with increased episode-related costs.

CONCLUSIONS

MACEs and SCEs represent a common and costly burden in the year following ACS hospitalization. Our findings may inform future economic assessments of new therapies aimed at prevention of MACEs and SCEs.

Can lipoprotein-associated phospholipase A2 be used as a predictor of long-term outcome in patients with acute coronary syndrome?

Studies indicate that elevated plasma concentrations of lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with increased risk of cardiovascular disease. Lp-PLA2 seems to play a crucial role in the formation of plaques and acute inflammation, and plasma Lp-PLA2 could therefore potentially be used as a predictor of long-term outcome in ACS patients. To evaluate this, data concerning Lp-PLA2 as a predictor in ACS patients was gathered through a systematic literature review, and studies on this issue were extracted from relevant databases, incl. PubMed and Cochrane. A total of 14 articles were retrieved, but after thorough evaluation and elimination of irrelevant articles only seven studies were eligible for the literature review. All studies except two showed significant correlation between Lp-PLA2 and CV events in ACS patients. Only one study found an independent value to predict CV events 30 days after ACS. Altogether, there was inconsistency in the findings regarding the potential use of Lp-PLA2 and a lack of knowledge on several issues. Lp-PLA2 seems to give valuable information on which ACS patients are prone to new events and also provides important information on plaque size. However, more focused studies concerning genetic variations, time-window impact, patients with and without CV risk factors (e.g. diabetes), and treatment effects are needed. In conclusion, Lp-PLA2 offers new insight in the pathophysiological development of ACS, but until the aforementioned issues are addressed the biomarker will mainly be of interest in a research setting, not as a predictive parameter in a clinical setting.

Latest drug developments in the field of cardiovascular disease

Cardiovascular disease has been responsible for more deaths annually than any other disease category since 1900, except for the influenza epidemic in 1916. Yet, the drug pipeline has been largely bereft of new entrants. In 2008, one new cardiovascular medication was marketed in the United States. In 2009, there were two new cardiovascular medications. In comparison, there were seven new drugs for oncology in 2009. The present review explores new agents within the context of models currently in the drug pipeline. Of course, there is no guarantee that any of these agents will be marketed. A discussion of the models is illustrative of the types of approaches being used to develop new cardiovascular agents.

Phospholipase A2 inhibition and atherosclerotic vascular disease: prospects for targeting secretory and lipoprotein-associated phospholipase A2 enzymes

PURPOSE OF REVIEW

Selective inhibitors of secretory phospholipase A2 and lipoprotein-associated phospholipase A2 are potential candidates for reducing recurrent cardiovascular events in patients with established coronary heart disease (CHD). With the active enrollment of CHD patients into phase III clinical trials with both classes of inhibitors, this article reviews the available experimental animal and human trial evidence that provides the rationale for the development of the phospholipase A2 inhibitors varespladib methyl and darapladib as preventive therapy.

RECENT FINDINGS

Recently completed experimental animal studies, human biomarker data, and vascular imaging studies provide support for proceeding with clinical outcome trials secretory phospholipase A2 and lipoprotein-associated phospholipase A2 inhibition.

SUMMARY

Both secretory phospholipase A2 and lipoprotein-associated phospholipase A2 inhibitors hold promise for the reduction of recurrent cardiovascular events in patients treated with current standards of care. The completion of the ongoing clinical event trials has the potential to provide a new dimension to secondary preventive therapy.