Ginsenoside Rb1 downregulates proinflammatory cytokines expression via the Tlr2/Tlr4 signaling pathway in mice with...

Autoimmune myocarditis is characterized by localized or diffuse inflammation of the myocardium due to immune dysfunction. A significant bioactive component of ginseng, ginsenoside, is used in the treatment of cancer, immune disorders, and diabetes. Among the various ginsenosides, ginsenoside Rb1 stands out for its antiviral, anti-inflammatory, antioxidant, anti-apoptotic, and autophagy-modulating effects. We expect the protective role of ginsenoside Rb1 in a MyHC-α614-629-induced experimental autoimmune myocarditis (EAM) mouse model.

Forty-eight Balb/c mice were randomly and equally divided into six groups: the negative control group, the EAM group, the PBS group, and three ginsenoside Rb1 treatment groups (20 mg/kg, 40 mg/kg, and 80 mg/kg). After the second immunization, mice received daily oral gavage of ginsenoside Rb1 at doses of 20, 40, and 80 mg/kg. On Day 21, the mouse heart and spleen tissues were isolated and weighed, the proportion of peripheral blood lymphocytes was detected. HE staining was used to observe pathological changes in myocardial tissue; Masson staining was used to detect fibrosis changes in myocardial tissue; Immunohistochemical detection of changes in the expression of cardiac troponin I (cTnⅠ), CD4, CD8, F4/80, IL-1β, Tlr2, and Tlr4; qRT-PCR and Western blotting detect the expression changes of CD4, CD8, F4/80, Ly6G, cTnⅠ, IL-1α, IL-1β, IL-6, Tlr2, and Tlr4 signaling pathway related genes in myocardial tissue.

EAM mice had significant cardiac enlargement (P < 0.001) and pallor. The EAM group exhibited slow body weight (BW) gain, alongside increased heart weight (HW), spleen weight (SW), and HW/BW ratios (P < 0.001). Additionally, there was an increase in the proportions of peripheral blood lymphocytes (P < 0.001). Inflammatory infiltration and fibrosis in myocardial tissue were aggravated, accompanied by upregulation of immune cell markers F4/80, CD4, and CD8, as well as the myocardial injury marker cTnⅠ (P < 0.001). Treatment with 40 and 80 mg/kg of ginsenoside Rb1 significantly improved these phenotypic and pathological features. Mechanistic analysis revealed notable upregulation of IL1-α, IL-1β, IL-6, Tlr2, Tlr4, Notch1, and Hes1 in the myocardial tissues of EAM mice, with IL-6 showing the most significant increase (P < 0.001).

Ginsenoside Rb1 provides protective effects in EAM mice by downregulating proinflammatory cytokines expression through the Tlr2/Tlr4 signaling pathway. This study lays the groundwork for potential clinical treatments for myocarditis.