HDAC Inhibitors as Epigenetic Regulators

Cardiac contractility and relaxation were significantly ameliorated in MSC-treated compared with PBS-injected CVB3-infected mice, as indicated by a 1.5-fold (P= 0.0002) and 1.7-fold (P= 0.001) improvement in the contractility parameters dP/dtmaxand dP/dtmin, respectively (Physique5). MSCs required priming via interferon- (IFN-) to exert their protective effects.In vivo, MSC application improved the contractility and relaxation parameters in CVB3-induced myocarditis, which was paralleled with a reduction in cardiac apoptosis, cardiomyocyte 21-Norrapamycin damage, left ventricular tumour necrosis factor- mRNA expression, and cardiac mononuclear cell activation. Mesenchymal stem cells reduced the CVB3-induced CD4 and CD8 T cell activation in an NO-dependent way and required IFN- priming. == Conclusion == We conclude that MSCs improve murine acute CVB3-induced myocarditis via their anti-apoptotic and immunomodulatory properties, which occur in an NO-dependent manner and require priming via IFN-. Keywords:Mesenchymal stem cells, Coxsackievirus, Apoptosis, Immunoregulation, Nitric 21-Norrapamycin oxide, Interferon- == Introduction == Myocarditis is usually a common inflammatory cardiomyopathy which can lead to a chronic impaired left ventricular (LV) function. Many different infectious brokers have been considered the cause of viral myocarditis, including enteroviruses, adenovirus, cytomegalovirus, hepatitis C virus, parvovirus B19, and others. Among the most commonly identified infectious brokers are the coxsackie B viruses (CVB), members of the enteroviral family. A direct CVB3-mediated injury of the cardiomyocytes in infected hearts1,2as well as cardiac inflammation3underlies CVB3-induced viral myocarditis. Under present pharmacological treatment, which is mainly focused on decreasing the activity of the neuroendocrine system, the prognosis against virus-induced inflammatory cardiomyopathy is not improved. This might be due to the lack of effects on the direct virus-induced components of the disorder. Therefore, different strategies, including gene therapeutic approaches and pharmaca directed at blocking viral replication or stimulating the anti-viral directed immune response,4are under investigation in experimental5and/or clinical studies.6 There is accumulating experimental2and clinical support7,8for the application of cellular transplantation as a 21-Norrapamycin strategy to improve myocardial function. Mesenchymal stem cells (MSCs) have anti-apoptotic,9anti-fibrotic,10and pro-angiogenic11features. They have the advantage over other stem cells that they are non-immunogenic, enabling the use of allogeneic MSCs for clinical application.8Moreover, MSCs have immunomodulatory properties,12which make them an attractive cell source for the treatment of virus-induced inflammatory cardiomyopathy, given the importance of the inflammatory component in this disorder. Among others, MSCs suppress T cell responses,13,14induce apoptosis of activated T cells,15and increase T regulatory cells.16Interferon- (IFN-) has been shown PECAM1 to play an important role in priming MSC-mediated immunoregulatory effects12,17as well as in inducing nitric oxide (NO) production in MSCs.18On the other hand, NO exerts anti-apoptotic effects on cardiomyocytes19,20and has anti-viral properties.21Moreover, MSCs have been shown to exert their immunomodulatory effects in an NO-dependent manner.12 The present study focuses at investigating whether MSCs are potential candidates for the treatment of acute CVB3-induced inflammatory cardiomyopathy. In view of clinical translation, the safety aspect whether MSCs can be infected by CVB3 is usually investigated. In addition, the study focuses at evaluating whether and how MSCs can (i) reduce the direct CVB3-mediated cardiomyocyte injuryin vitro, and (ii) decrease cardiac apoptosis and improve LV function in an experimental model of murine acute CVB3-induced myocarditis. Furthermore, the role of NO and of IFN- priming in the MSC-mediated protective effects is investigated. == Methods == For detailed methodology, please seeSupplementary material online. Human adult MSCs were isolated from iliac crest bone marrow aspirates of normal male donors (n= 6) after their written approval. Mesenchymal stem cells were characterized by flow cytometry analysis according to Bingeret al.22To investigate whether MSCs can be infected with CVB3, MSCs were serum starved or exposed to CVB3 at a multiplication of infection (m.o.i.) of 5 for 1 h under serum-starvation conditions. Next, cell morphology, cell viability, and CVB3 RNA copy number were evaluated 4, 12, 24, and 48 h after serum starvation/contamination via phase contrast pictures, MTS viability assay, and real-time PCR, respectively. Next, to determine whether MSCs can protect against direct CVB3-induced cardiomyocyte damage, MSCs were co-cultured with uninfected or CVB3-infected HL-1 cardiomyocytes at a ratio of 1 1 MSC to 10 HL-1. The effect of MSC supplementation on CVB3-induced HL-1 cardiomyocyte apoptosis, oxidative stress, virion progeny release, and intracellular virion production was decided via annexin V/7AAD flow cytometry and caspase 3/7 activity analysis, DCF flow cytometry, and plaque assay,.