Abstract

Inflammation and myocardial weakness, two major hallmarks of chronic viral myocarditis (VMC), often lead to dilated cardiomyopathy or chronic heart failure. It has been reported that indoleamine 2,3-dioxygenase-1 (IDO1) may play a pathogenic role in the progression of inflammatory diseases. Hence, the study is set out to investigate the potential role of IDO1 in chronic VMC by establishing a mouse model of VMC by intraperitoneally injected with coxsackievirus B3 (CVB3). After model establishment, the expression of IDO1 was determined by RT-qPCR and Western blot analysis. IDO1 was identified as an up-regulated gene in CVB3-induced VMC. Then, in order to elucidate the potential role of IDO1 in VMC, macrophages were isolated and treated with the overexpression plasmid of IDO1 or IDO1 inhibitor (1-MT). After that, these transfected macrophages were co-cultured with normal cardiomyocytes, followed by measurement of inflammatory factors and evaluation of cardiomyocyte injury. The overexpression of IDO1 was observed to significantly enhance the levels of interleukin (IL)-6, IL-1β and tumor necrosis factor-α (TNF-α), as well as lactate dehydrogenase (LDH) activity and malondialdehyde (MDA) content. By contrast, the treatment of 1-MT in macrophages reversed the promoting effects of IDO1 on cardiomyocyte injury. Co-culture experiment showed that overexpressed IDO1 impaired cardiomyocyte, which was alleviated upon treatment of 1-MT. Taken together, the key findings of the present study provide evidence that 1-MT-mediated IDO1 suppression could potentially reduce inflammatory response in macrophages and consequently ameliorate cardiomyocyte injury in mice with VMC.