Matrine promotes macrophage polarization to repair myocardial tissue injury in rats

Abstract

BACKGROUND: Matrine exerts therapeutic effects on pneumonia, sepsis, and hepatitis B because of its significant anti-inflammatory and anti-tumor properties. However, its role and mechanisms in macrophage-mediated inflammation post myocardial infarction remain poorly understood. OBJECTIVE: To investigate the effects of matrine on inflammation and myocardial tissue repair following myocardial infarction, and to clarify its potential molecular mechanism. METHODS: (1) In vivo experiment: 32 Sprague-Dawley rats were randomly divided into sham operation group, myocardial infarction group, low-dose matrine [200 mg/(kg·d)] group, and high-dose matrine [300 mg/(kg·d)] group, with 8 rats in each group. Myocardial infarction model was established in rats. Matrine was continuously gavaged for 3 days after surgery. On day 4, echocardiography and serum inflammatory cytokine levels were detected, and heart tissues were collected for histological analysis (hematoxylin-eosin staining, Masson staining) to assess myocardial injury. (2) In vitro experiment: Mouse bone marrow-derived macrophages were isolated and induced with lipopolysaccharide to establish an inflammation model, then treated with 10 μmol/L or 20 μmol/L matrine. Western blot, RT-qPCR, and flow cytometry were used to detect M1/M2 macrophage markers (inducible nitric oxide synthase, CD86, arginase 1, CD206) expression and cell proportions. Western blot was used to detect phosphorylation levels of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3). Additionally, H9C2 cells were used to construct a hypoxia injury model to evaluate the effect of matrine on cellular reactive oxygen species levels. RESULTS AND CONCLUSION: (1) In vivo: Matrine significantly improved cardiac function in myocardial infarction rats. Compared with the myocardial infarction group, both low-dose and high-dose matrine groups significantly increased left ventricular ejection fraction and left ventricular fractional shortening, with the high-dose group showing more pronounced improvement. Furthermore, matrine significantly inhibited the elevation of peripheral inflammatory cytokines (interleukin-1β and interleukin-6) after myocardial infarction. Histopathological analysis showed that matrine effectively reduced myocardial inflammatory cell infiltration, collagen deposition area, tissue edema, and necrosis range. (2) In vitro: RT-qPCR and Western blot results showed that matrine significantly inhibited the expression of M1 markers (inducible nitric oxide synthase, CD86) while upregulating M2 markers (arginase 1, CD206). Flow cytometry showed a decrease in CD86-positive cells and a significant increase in CD206-positive cells. Additionally, matrine significantly reduced intracellular reactive oxygen species levels. (3) Signaling pathway: Western blot results showed that matrine significantly inhibited the phosphorylation of JAK2 and STAT3 proteins, blocking pro-inflammatory signal transduction and promoting macrophage phenotype switch, thereby exerting anti-inflammatory effects. These results indicate that matrine can promote macrophage polarization toward M2 phenotype by inhibiting the JAK/STAT pathway, attenuate post-myocardial infarction inflammation, and protect cardiomyocytes in a dose-dependent manner.

1. Introduction

Myocardial infarction and subsequent heart failure are key factors leading to long-term disability and death in patients [1-2]. With the update of treatment methods, the short-term mortality rate after acute myocardial infarction (in-hospital or within 30 days) is declining, but the long-term mortality rate (1 year and above) remains high, mainly due to the increasing number of patients who survive acute myocardial infarction but eventually develop heart failure [3-4]. To improve the prognosis of patients with myocardial infarction, the development of new therapeutic methods is crucial, aiming to reduce the inflammatory response after myocardial infarction, shrink the infarct size, maintain left ventricular function, and prevent the progression of heart failure [5].

The inflammatory response after myocardial infarction is a key factor determining the final infarct size and ventricular remodeling, making control of inflammation an important means of myocardial protection [6]. The initial acute inflammatory response after acute myocardial infarction is triggered by the innate immune response to cell necrosis, including the release of mitochondrial DNA fragments into tissues, complement activation, and inflammasome formation [7]. Macrophages, as the main immune cells in the body, play a key role in the inflammatory environment after myocardial infarction [8]. In the early stage of myocardial infarction, macrophages are recruited into the infarcted tissue, and undifferentiated macrophages (M0) polarize into pro-inflammatory M1 macrophages under the stimulation of a large number of inflammatory mediators and cytokines in the infarct area [9]. M1 macrophages aggravate the inflammatory response by releasing a series of inflammatory cytokines such as interleukin-1β and interleukin-6, promoting pathogen clearance and inflammation maintenance [10-11]. In the late stage of myocardial infarction, M1 macrophages gradually polarize into anti-inflammatory M2 macrophages, which release anti-inflammatory cytokines such as interleukin-10 [12], playing an important role in inhibiting inflammation, promoting fibrosis, tissue repair, and angiogenesis in the infarct area [13-14]. Studies have pointed out that regulating the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway can promote fibrotic repair after myocardial infarction [15]. Therefore, by regulating the immune microenvironment and inducing macrophage polarization from M1 to M2, it is of great significance to attenuate the inflammatory response after myocardial infarction and promote myocardial repair.