Rakesh Chaudhary

The utility of cardiac biomarkers and echocardiography for the early detection of bevacizumab- and sunitinib-mediated cardiotoxicity

The recent introduction of novel anticancer therapies, including bevacizumab (BVZ) and sunitinib (SNT), is associated with an increased risk of cardiotoxicity. However, early identification of left ventricular (LV) systolic dysfunction may facilitate dose modification and avoid the development of advanced heart failure. Using a murine model of BVZ- and SNT-mediated cardiotoxicity, we investigated whether cardiac biomarkers and/or tissue velocity imaging (TVI) using echocardiography can detect early changes in cardiac function, before a decrease in LV ejection fraction is identified. A total of 75 wild-type C57Bl/6 male mice were treated with either 0.9% saline, BVZ, or SNT. Serial monitoring of blood pressure, high-sensitivity troponin I, and echocardiographic indexes were performed over a 14-day study period, after which the mice were euthanized for histological and biochemical analyses. Mice treated with either BVZ or SNT developed systemic hypertension as early as day 7, which increased by day 14. Cardiac biomarkers, specifically high-sensitivity troponin I, were not predictive of early LV systolic dysfunction. Although conventional LV ejection fraction values decreased at day 13 in mice treated with either BVZ or SNT, TVI confirmed early LV systolic dysfunction at day 8. Histological and biochemical analysis demonstrated loss of cellular integrity, increased oxidative stress, and increased cardiac apoptosis in mice treated with BVZ or SNT therapy at day 14. In a murine model of BVZ- or SNT-mediated cardiomyopathy, noninvasive assessment by TVI detected early LV systolic dysfunction before alterations in conventional echocardiographic indexes.

Congenital Absence of Nitric Oxide Synthase 3 Potentiates Cardiac Dysfunction and Reduces Survival in Doxorubicin- and Trastuzumab-Mediated Cardiomyopathy

BACKGROUND Doxorubicin (DOX) and trastuzumab (TRZ) are highly effective chemotherapeutic agents in the breast cancer setting, limited by their cardiotoxic side effects. Among the potential mechanisms for this drug-induced cardiomyopathy, increased production of oxidative stress (OS) through a nitric oxide synthase 3 (NOS3)-dependent pathway has gained recent attention. The objective of the study was to determine the role of NOS3 and OS in a clinically relevant female murine model of DOX- and TRZ-induced heart failure. METHODS A total of 120 female mice (60 wild-type [WT] and 60 NOS3 knockout [NOS3(-/-)]) were treated with either 0.9% saline, DOX, TRZ, or DOX with TRZ (DOX+TRZ). Serial echocardiography was performed for a total of 10 days, after which the mice were euthanized for histological and biochemical analyses. RESULTS In WT female mice receiving DOX+TRZ, left ventricular ejection fraction (LVEF) decreased from 75 ± 3% at baseline to 46 ± 2% at day 10 (P < 0.05). In the NOS3(-/-) group, LVEF decreased from 72 ± 3% at baseline to 35 ± 2% at day 10 (P < 0.05). LVEF was significantly lower in NOS3(-/-) female mice receiving DOX+TRZ than WT mice at day 10 (P < 0.05). Compared with WT, NOS3(-/-) female mice also demonstrated increased mortality after treatment with DOX+TRZ, corroborating the echocardiographic findings. Histological analysis demonstrated increased myofibrillar degradation and loss of cell integrity in NOS3(-/-) female mice treated with DOX+TRZ. There was increased generation of oxidized phosphatidylcholine, a marker of OS, in NOS3(-/-) female mice receiving DOX+TRZ compared with control mice. CONCLUSIONS Congenital absence of NOS3 potentiates the cardiotoxic side effects of DOX+TRZ in an acute female murine model of chemotherapy-induced cardiomyopathy.

Role of Phospholipases and Oxidized Phospholipids in Inflammation

Long thought of as a bystander in pathophysiological processes, lipid molecules have emerged as bioactive mediators of cellular activity. Oxidized phospholipids (OxPLs), generated during enzymatic and non-enzymatic processes, modulate cellular processes through receptor-mediated pathways that can effect a whole host of activities including apoptosis, monocyte adhesion, platelet aggregation, and regulation of immune responses. Initially discovered as platelet activating factor analogs, there have been close to 50 distinct OxPL molecules that have been identified within biological tissues. With the advent of robust analytical systems, we are better able to identify and quantitate these molecules in an ever growing list of different biological tissues which has allowed for the generation of a comprehensive oxolipid profiles in both normal and disease states. Given the increased affinity of phospholipases towards OxPLs we are in the early stages of understanding of the complex interplay between the modification of OxPL through phospholipase activity and the cellular responses to the released hydrolyzed products. In this review we will summarize the role of OxPL in different pathological states and the specific phospholipases that have been shown to interact with OxPLs.

INCREASED PRODUCTION OF OXIDIZED PHOSPHOTIDYLCHOLINE MOLECULES IN PATIENTS PRESENTING WITH STEMI

BACKGROUND: Despite restoration of blood flow to myocardial cells after ischemia, a large percentage of myocardial cells die after reperfusion. Oxidized phophatidylcholines (OxPC) are a group of molecules that are generated during reperfusion that have been shown to mediate inflammation, platelet aggregation, thrombosis and cell death, however their presence and role in STEMI remains unclear. METHODS: Blood and coronary thrombectomy samples were collected from 13 subjects with STEMI and 4 subjects with non-obstructive CAD prior to, and at completion of angioplasty/angiography respectively. The complete oxidative lipidomic profile at the onset of STEMI and after reperfusion was compared to control prior to and after diagnostic angiography. The oxidative lipidomic profile of each was established and compared using high-performance electrospray mass spectrometry of plasma and coronary thrombectomy samples. RESULTS: Thirteen STEMI subjects age 57 8years and 4 patients age 56 8 years who presented for clinically indicated coronary angiography/angioplasty were enrolled in this study. Seventy-nine distinct OxPC molecules were identified in human plasma. During ischemia, 22 OxPC molecules were significantly different compared to control subjects and following reperfusion, 40 OxPC molecules were significantly different compared to control subjects. Fragmented OxPC molecules in the control vs ischemia population went from 3.8 vs 20.6ng/mg of protein, (p 1⁄4 0.07) and with reperfusion increased to 1.8 vs 34.7ng/mg of protein, (p1⁄40.01) and was 54.8ng/mg of protein in the coronary thrombus sample, increased compared to reperfusion (p1⁄40.3). The increase in fragmented OxPCs in plasma during reperfusion was due to a significant increase in carboxylic acid OxPCs and aldehyde OxPCs. In coronary thrombus, the increase in fragmented OxPCs was due to a significant increase in aldehyde OxPCs only. In all, fragmented OxPCs increased by 5 fold with onset of ischemia, 19 fold with reperfusion. While coronary thrombus had the highest concentration of fragmented OxPCs, it did not correlate with plasma samples indicating that thrombus and reperfusion samples were independent of one another. CONCLUSION: We have shown for the first time that OxPC molecules are present in human STEMI subjects during ischemia, reperfusion and coronary thrombus. Consistent with reperfusion injury, OxPC levels undergo marked increases with reperfusion. Coronary thrombus contains high levels of OxPCs due to coronary plaque disruption and is independent of reperfusion. In light of our findings, attenuation of the biologic effects of OxPCs may be a novel therapeutic approach to reduce the deleterious effects of reperfusion injury.