Department of Cardiology, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan, China.
Department of Cardiology, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan 430060, China; Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China; Hubei Key Laboratory of Cardiology, Wuhan, China.
Biomed Pharmacother. 2023 Sep;165:115083. doi: 10.1016/j.biopha.2023.115083. Epub 2023 Jul 4.
OBJECTIVES/AIMS: Inflammation is crucial in structural and electrical remodeling after myocardial infarction (MI), affecting cardiac pump function and conduction pathways. Phloretin possesses an anti-inflammation role by inhibiting the NLRP3/Caspase-1/IL-1β pathway. However, the effects of Phloretin on cardiac contractile and electrical conduction function after MI remained unclear. Therefore, we aimed to investigate the potential role of Phloretin in a rat model of MI.
Rats were assigned into four groups: Sham, Sham+Phloretin, MI and MI+Phloretin, with ad libitum food and water. In the MI and MI+Phloretin groups, the left anterior descending coronary artery was occluded for 4 weeks, while the Sham and Sham+Phloretin groups received sham operation. The Sham+Phloretin group and the MI+Phloretin group received oral administration of Phloretin. In vitro, H9c2 cells were subjected to hypoxic conditions to simulate an MI model, with Phloretin for 24 h. Cardiac electrophysiological properties were assessed following MI, including the effective refractory period (ERP), action potential duration (APD)90 and ventricular fibrillation (VF) incidence. Echocardiography evaluated left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), left ventricular internal diameter at end-diastole (LVIDd), left ventricular internal diameter at end-systole (LVIDs), left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) to assess cardiac function. Serum type B natriuretic peptide (BNP) level was applied to evaluate the degree of Heart failure (HF). The fibrosis area and severity were assessed by Masson staining and protein expression levels of collagen 3, collagen 1, TGF-β and α-SMA. Western blot analysis estimated the protein expression levels of NLRP3, Pro Caspase-1, Caspase-1, ASC, IL-18, IL-1β, pp38, p38, and Connexin43(Cx43) to elucidate the influence of inflammation on electrical remodeling after MI.
Our findings demonstrate that Phloretin inhibits the NLRP3/Caspase-1/IL-1β pathway, leading to the upregulation of Cx43 by limiting p38 phosphorylation, which further decreases susceptibility to ventricular arrhythmias (VAs). Additionally, Phloretin attenuated fibrosis by inhibiting inflammation to prevent HF. In vitro experiments also provided strong evidence supporting the inhibitory effects of Phloretin on the NLRP3/Caspase-1/IL-1β pathway.
Our results suggest that Phloretin could suppress the NLRP3/Caspase-1/IL-1β pathway to reverse structural and electrical remodeling after MI to prevent the occurrence of VAs and HF.
目的/目标：炎症在心肌梗死后的结构和电重构中起着关键作用，影响心脏泵功能和传导途径。根皮苷通过抑制 NLRP3/Caspase-1/IL-1β 通路发挥抗炎作用。然而，根皮苷对心肌梗死后心脏收缩和电传导功能的影响仍不清楚。因此，我们旨在研究根皮苷在大鼠心肌梗死后模型中的潜在作用。
大鼠被分为四组：假手术组、假手术+根皮苷组、心肌梗死组和心肌梗死+根皮苷组，自由进食和饮水。在心肌梗死和心肌梗死+根皮苷组中，结扎左前降支冠状动脉 4 周，而假手术和假手术+根皮苷组则接受假手术。假手术+根皮苷组和心肌梗死+根皮苷组给予根皮苷口服。在体外，将 H9c2 细胞置于缺氧条件下模拟心肌梗死模型，并用根皮苷处理 24 小时。心肌梗死后评估心脏电生理特性，包括有效不应期（ERP）、动作电位时程 90（APD90）和室颤（VF）发生率。超声心动图评估左心室射血分数（LVEF）、左心室缩短分数（LVFS）、左心室舒张末期内径（LVIDd）、左心室收缩末期内径（LVIDs）、左心室收缩末期容积（LVESV）和左心室舒张末期容积（LVEDV），以评估心功能。血清 B 型利钠肽（BNP）水平用于评估心力衰竭（HF）程度。通过 Masson 染色和胶原 3、胶原 1、TGF-β和α-SMA 的蛋白表达水平评估纤维化面积和严重程度。Western blot 分析估计 NLRP3、Pro Caspase-1、Caspase-1、ASC、IL-18、IL-1β、pp38、p38 和连接蛋白 43（Cx43）的蛋白表达水平，以阐明炎症对心肌梗死后电重构的影响。
我们的研究结果表明，根皮苷通过限制 p38 磷酸化来抑制 NLRP3/Caspase-1/IL-1β 通路，从而上调 Cx43，进一步降低心室性心律失常（VAs）的易感性。此外，根皮苷通过抑制炎症减轻纤维化，预防 HF。体外实验也为根皮苷抑制 NLRP3/Caspase-1/IL-1β 通路提供了有力证据。
我们的结果表明，根皮苷可能通过抑制 NLRP3/Caspase-1/IL-1β 通路来逆转心肌梗死后的结构和电重构，以防止 VAs 和 HF 的发生。
