Astragaloside IV in Combination with Tanshinone IIA Ameliorates Cardiac Fibrosis After Myocardial Infarction by Inhibiting CTR1/ATOX1/LOX Axis-Mediated Collagen Cross-Linking in Myofibroblasts

Purpose: This study aims to elucidate the molecular mechanism underlying the therapeutic effect of AS-IV in combination with Tan IIA in ameliorating cardiac fibrosis by inhibiting excessive Collagen cross-linking following myocardial infarction (MI).

Methods: MI model mice were administered AS-IV and Tan IIA for a duration of four weeks. After the treatment was completed, serum and cardiac specimens were collected from the mice to assess cardiac Collagen fiber deposition, Collagen cross-linking, cardiac function, copper homeostasis, Lysyl Oxidase (LOX) content, and the expression of related molecules. Meanwhile, utilizing an in vitro model of myofibroblasts and employing CTR1 overexpression or siRNA-mediated CTR1 silencing and recombinant LOX, we systematically investigated the effects of AS-IV and Tan IIA on key phenotypic features in myofibroblasts, including cross-linking and copper levels.

Results: Our results demonstrate that AS-IV and Tan IIA significantly inhibited excessive Collagen cross-linking in infarcted hearts, reduced cardiac Collagen deposition, and consequently attenuated adverse cardiac remodeling while preserving cardiac function. Mechanistically, AS-IV and Tan IIA suppress intracellular copper accumulation by downregulating the CTR1/ATOX1 axis in the copper transport pathway within myofibroblasts. This downregulation subsequently reduces both the expression and enzymatic activity of LOX, a copper-dependent enzyme, thereby inhibiting excessive Collagen cross-linking in these cells. Moreover, AS-IV and Tan IIA demonstrate potential in restoring abnormal copper homeostasis after myocardial infarction and modulating copper distribution within myofibroblasts.

Conclusion: AS-IV and Tan IIA attenuate Collagen cross-linking in myofibroblasts by downregulating the CTR1/ATOX1/LOX axis, thereby reducing aberrant Collagen cross-linking and deposition in the infarcted heart and ultimately inhibiting cardiac fibrosis.