Chinese medicinal herb Radix Astragali suppresses cardiac contractile dysfunction and inflammation in a rat model of autoimmune myocarditis

Radix Astragali, a Chinese medicinal herb, consists of polysaccharides and flavonoids as its main active ingredients. It has been widely used for treatment of cardiovascular diseases such as heart failure, angina pectoris, myocardial infarction and stroke in Asian countries. This study was designed to evaluate the effect of Radix Astragali on myocardial dysfunction, cardiac remodeling and morphological alteration in an experimental model of autoimmune myocarditis, a clinical condition often resulting in dilated cardiomyopathy. Experimental autoimmune myocarditis was established with a subcutaneous injection of porcine cardiac myosin into rear footpad in Lewis rats. Radix Astragali treatment was delivered via an intravenous injection (0.2 ml/100 g body weight, daily) for 3 weeks. Results from transthoracic echocardiography indicated that experimental autoimmune myocarditis led to impaired myocardial contractile function which was reconciled by Radix Astragali. The experimental autoimmune myocarditis triggered profound inflammation and fibrosis in myocardium as assessed by hematoxylin and eosin (H and E) and Masson’s trichrome staining. Interestingly, Radix Astragali significantly attenuated autoimmune myocarditis-induced myocardial inflammation and fibrosis. Similarly, Radix Astragali treatment alleviated autoimmune myocarditis-triggered overt lymphocyte proliferation. Furthermore, Radix Astragali significantly attenuated elevated levels of the Th1 cytokines (IFN-γ and IL-2), and increased the Th2 cytokines (IL-4 and IL-10) in autoimmune myocarditis. Collectively, our data revealed that Radix Astragali effectively protected against cardiac functional and morphological aberrations in experimental autoimmune myocarditis.