Agorrody, Guillermo

Abstract Aims Doxorubicin (DXR) is a chemotherapeutic agent that causes dose-dependent cardiotoxicity. Recently, it has been proposed that the NADase CD38 may play a role in doxorubicin-induced cardiotoxicity (DIC). CD38 is the main NAD+-catabolizing enzyme in mammalian tissues. Interestingly, in the heart, CD38 is mostly expressed as an ecto-enzyme that can be targeted by specific inhibitory antibodies. The goal of the present study is to characterize the role of CD38 ecto-enzymatic activity in cardiac metabolism and the development of DIC. Methods and results Using both a transgenic animal model and a non-cytotoxic enzymatic anti-CD38 antibody, we investigated the role of CD38 and its ecto-NADase activity in DIC in pre-clinical models. First, we observed that DIC was prevented in the CD38 catalytically inactive (CD38-CI) transgenic mice. Both left ventricular systolic function and exercise capacity were decreased in wild-type but not in CD38-CI mice treated with DXR. Second, blocking CD38-NADase activity with the specific antibody 68 (Ab68) likewise protected mice against DIC and decreased DXR-related mortality by 50%. A reduction of DXR-induced mitochondrial dysfunction, energy deficiency, and inflammation gene expression were identified as the main mechanisms mediating the protective effects. Conclusion NAD+-preserving strategies by inactivation of CD38 via a genetic or a pharmacological-based approach improve cardiac energetics and reduce cardiac inflammation and dysfunction otherwise seen in an acute DXR cardiotoxicity model.

Abstract Obesity-related type II diabetes (diabesity) has increased global morbidity and mortality dramatically. Previously, the ancient drug salicylate demonstrated promise for the treatment of type II diabetes, but its clinical use was precluded due to high dose requirements. In this study, we present a nitroalkene derivative of salicylate, 5-(2-nitroethenyl)salicylic acid (SANA), a molecule with unprecedented beneficial effects in diet-induced obesity (DIO). SANA reduces DIO, liver steatosis and insulin resistance at doses up to 40 times lower than salicylate. Mechanistically, SANA stimulated mitochondrial respiration and increased creatine-dependent energy expenditure in adipose tissue. Indeed, depletion of creatine resulted in the loss of SANA action. Moreover, we found that SANA binds to creatine kinases CKMT1/2, and downregulation CKMT1 interferes with the effect of SANA in vivo. Together, these data demonstrate that SANA is a first-in-class activator of creatine-dependent energy expenditure and thermogenesis in adipose tissue and emerges as a candidate for the treatment of diabesity.

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

Background: Cardiac tissue possesses high energetic requirements. During development of heart failure there is a shift from fatty acid oxidation to the utilization of other substrates. This transition leads to the decline in NAD/NADH ratio, which increases susceptibility to stress. CD38 is the main NAD + -consuming enzyme responsible for NAD + levels regulation in tissue and therefore represents a possible therapeutic target in such conditions. Objective: To investigate the role of CD38 in cardiovascular performance and its potential use as a therapeutic target in obesity-induced heart failure. Results: When comparing adult Wild-Type (WT) and CD38 Knock-out (KO) mice we observed that the latter had higher exercise performance, increased heart rate variability (HRV) and decreased heart rate (HR). When comparing WT and CD38 catalytically inactive (CI) mice we observed the same results, showing its relation with CD38 catalytic activity. WT mice treated with an antibody which blocks CD38 activity showed improved exercise capacity and HRV. In both genetically modified or antibody treated groups, NAD+ levels were significantly increased in heart. In order to explore the NAD + role in these findings, we compared WT control and CD38KO treated with FK866 (Nampt inhibitor) and observed that NAD+ levels in heart decreased as well as exercise capacity. We then aimed to demonstrate CD38 role as a target for therapeutic intervention in a model of cardiac strain induced by obesity in aged mice. We compared WT and CD38 CI aged mice, placed in normal diet (ND) or high fat diet (HFD). WT animals fed HFD showed decreased exercise capacity and this effect is reversed in CD38 CI fed HFD. Similarly, WT placed in HFD developed diastolic dysfunction seen as a significant increase in E/e’ ratio, and CD38 CI placed in HFD were protect against the development of this dysfunction. Mechanistically, we observed that blockage of CD38 resulted in decreased protein acetylation and increased SERCA expression. Conclusion: CD38 plays a role in cardiovascular performance by regulation of NAD + homeostasis. In a model of obesity-induced diastolic dysfunction NAD+-boosting by blocking CD38 activity led to protection by up-regulating SERCA expression.

Background: Doxorubicin is a chemotherapy medication used to treat several types of cancer. Its major adverse effect is cardiotoxicity, which may limit its use. Doxorubicin-induced cardiotoxicity (DIC), once developed, carries a poor prognosis. Therefore strategies to prevent or treat DIC are of paramount importance but have not yet been fully developed. Being NAD + a critical nucleotide which is involved in oxy-reduction reactions and CD38 the main NAD + -consuming enzyme responsible for NAD levels regulation and homeostasis, we aim to investigate the link of CD38 and NAD + metabolism in DIC and its potential role as a therapeutic target. Methods: We compared Wild-type (WT) control mice with WT mice treated with a single dose injection of 15 mg/kg of doxorubicin who received vehicle or an antibody that blocksCD38 ecto-enzymatic activity. We also compared genetically CD38 catalytic inactive (CI) mice treated or not with the same single dose injection. Results: Doxorubicin caused a decrease in Ejection Fraction (EF) in WT mice. We also observed that CD38 CI mice treated with doxorubicin did not have changes in EF compared to their control. When compared to WT receiving just doxorubicin, WT mice treated also with the antibody had a trend to improve EF. As for exercise performance, our results show a decrease in exercise capacity induced by doxorubicin that was reversed in the antibody group and did not happen in the CD38 CI mice treated with doxorubicin. Doxorubicin caused a decrease in heart rate variability (HRV) which was improved in the antibody treated group. Moreover, our results show a survival rate that is similar to what has been previously shown, with 50% mortality associated with doxorubicin. Blockage of CD38 activity with antibody reduced mortality in this model to approximately 20%. Mechanistically, we did not observe decreases in NAD+ levels induced by Doxorubicin. However, boost of NAD induced by blocking CD38 was related to protection against DIC. Conclusion: Our results indicate that the damage mechanism of DIC may not be related directly with NAD decrease, but NAD boosting induced by CD38 blockage seems to have a positive effect in protection against cardiac dysfunction related to this chemotherapeutic treatment.