SummaryCD40 plays an important role in the pathogenesis of myocarditis, and inhibition of CD40 expression could be a promising treatment for myocarditis. In this study, we used an animal model, experimental autoimmune myocarditis (EAM), to investigate whether CD40 siRNA could be exploited for myocarditis therapy.Lewis rats were immunized with purified porcine cardiac myosin to induce EAM or were injected with phosphatebuffered saline (PBS) alone (PBS group), scrambled small interfering RNA (siRNA) (negative control group), or CD40-siRNA (CD40 siRNA group).CD40 siRNA treatment suppressed the increase in heart weight/body weight ratio, and attenuated the severity of myocardial lesions. Cytokine production, including Th1-type cytokines, was significantly suppressed in rats with myocarditis after CD40 siRNA treatment; however, production of Th2-type cytokines was higher. Specific knockdown of CD40 in EAM rats resulted in increased FOXP3 gene expression and the CD25+ CD4+ subpopulation of T cells but also a decrease in CD80 and CD86 expression. Lymphocyte (T and B cell) proliferation in response to myosin stimulation was significantly inhibited by CD40 silencing.CD40-siRNA is a useful tool for inhibiting in vivo CD40 expression, and it could have therapeutic potential in the prevention and treatment of myocarditis in humans. (Int Heart J 2014; 55: 539-545) Key words: RNA interference, Lymphocyte M yocarditis, an inflammatory heart muscle disease associated with cardiac dysfunction, can be caused by many agents, such as viruses and drugs, and is a potentially lethal disease, which can cause sudden death.
1,2)The disease has acute and chronic phases. Patients with myocarditis may develop dilated cardiomyopathy, which represents the chronic phase of the disease that leads to heart failure.
3)While there is still no effective therapy for myocarditis, recent studies have shown that autoimmunity plays an important role in the pathogenesis and development of myocarditis. 4) Experimental autoimmune myocarditis (EAM) is a model of post-infectious myocarditis, and can be induced by severe myocardial damage, including infiltration of mononuclear cells into the myocardium and activation of dendritic cells (DCs), with the subsequent activation of autoreactive T-cells, along with the secreted cytokines.
5-7)RNA interference is a post-transcriptional mechanism of gene silencing in which siRNA can lead to specific endonucleolytic cleavage of mRNA.8) RNA interference with siRNA is a specific, long-lasting, and straightforward approach for blocking the expression of specific genes.9) The therapeutic use of siRNA is promising, due to sequence-specific gene silencing, and has been successfully used in several animal models of diseases and clinical trials.
10)CD40 is a member of the TNF receptor superfamily and, as a co-stimulatory molecule, it plays critical roles in T cell activation and differentiation.11,12) CD40 expression can stimulate Th1 activation, 13,14) and the CD40/CD40 ligand (CD40L) interaction has been demonstrated to e...