Isoproterenol induces MD2 activation by ß-AR-cAMP-PKA-ROS signalling axis in cardiomyocytes and macrophages drives inflammatory heart failure.

Cardiac inflammation contributes to heart failure (HF) induced by isoproterenol (ISO) through activating ß-adrenergic receptors (ß-AR). Recent evidence shows that myeloid differentiation factor 2 (MD2), a key protein in endotoxin-induced inflammation, mediates inflammatory heart diseases. In this study, we investigated the role of MD2 in ISO-ß-AR-induced heart injuries and HF. Mice were infused with ISO (30 mg·kg-1·d-1) via osmotic mini-pumps for 2 weeks. We showed that MD2 in cardiomyocytes and cardiac macrophages was significantly increased and activated in the heart tissues of ISO-challenged mice. Either MD2 knockout or administration of MD2 inhibitor L6H21 (10 mg/kg every 2 days, i.g.) could prevent mouse hearts from ISO-induced inflammation, remodelling and dysfunction. Bone marrow transplantation study revealed that both cardiomyocyte MD2 and bone marrow-derived macrophage MD2 contributed to ISO-induced cardiac inflammation and injuries. In ISO-treated H9c2 cardiomyocyte-like cells, neonatal rat primary cardiomyocytes and primary mouse peritoneal macrophages, MD2 knockout or pre-treatment with L6H21 (10 µM) alleviated ISO-induced inflammatory responses, and the conditioned medium from ISO-challenged macrophages promoted the hypertrophy and fibrosis in cardiomyocytes and fibroblasts. We demonstrated that ISO induced MD2 activation in cardiomyocytes via ß1-AR-cAMP-PKA-ROS signalling axis, and induced inflammatory responses in macrophages via ß2-AR-cAMP-PKA-ROS axis. This study identifies MD2 as a key inflammatory mediator and a promising therapeutic target for ISO-induced heart failure.

Clinical Impact of Thrombus Aspiration and Interaction With D-Dimer Levels in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention.

Objectives: To evaluate the effect of thrombus aspiration (TA) strategy on the outcomes and its interaction with D-dimer levels in patients with ST-segment elevation myocardial infarction (STEMI) during primary percutaneous coronary intervention (PCI) in "real-world" settings. Materials and Methods: This study included 1,295 patients with STEMI who had undergone primary PCI with or without TA between January 2013 and June 2017. Patients were first divided into a TA+PCI group and a PCI-only group, and the baseline characteristics and long-term mortality between the two groups were analyzed. Furthermore, we studied the effect of TA on the clinical outcomes of patients grouped according to quartiles of respective D-dimer levels. The primary outcome was all-cause mortality, and the secondary outcomes were new-onset heart failure (HF), rehospitalization, re-PCI, and stroke. Results: In the original cohort, there were no significant differences in all-cause mortality between the TA+PCI and PCI-only groups (hazard ratio, 0.789; 95% confidence interval, 0.556-1.120; p = 0.185). After a mean follow-up of 2.5 years, the all-cause mortality rates of patients in the TA + PCI and PCI-only groups were 8.5 and 16.2%, respectively. Additionally, differences between the two groups in terms of the risk of HF, re-PCI, rehospitalization, and stroke were non-significant. However, after dividing into quartiles, as the D-dimer levels increased, the all-cause mortality rate in the PCI group gradually increased (4.3 vs. 6.0 vs. 7.0 vs. 14.7%, p < 0.001), while the death rate in the TA+PCI group did not significantly differ (4.6 vs. 5.0 vs. 4.0 vs. 3.75%, p = 0.85). Besides, in the quartile 3 (Q3) and quartile 4 (Q4) groups, the PCI-only group was associated with a higher risk of all-cause mortality than that of the TA+PCI group (Q3: 4.0 vs. 7.0%, p = 0.029; Q4: 3.75 vs. 14.7%, p < 0.001). Moreover, the multivariate logistic regression analysis demonstrated that TA is inversely associated with the primary outcome in the Q4 group [odds ratio (OR), 0.395; 95% CI, 0.164-0.949; p = 0.038]. Conclusions: The findings of our real-world study express that routine manual TA during PCI in STEMI did not improve clinical outcomes overall. However, patients with STEMI with a higher concentration of D-dimer might benefit from the use of TA during primary PCI. Large-scale studies are recommended to confirm the efficacy of TA.