CTRP3 alleviates mitochondrial dysfunction and oxidative stress injury in pathological cardiac hypertrophy by activating UPRmt via the SIRT1/ATF5 axis.

Pathological cardiac hypertrophy is an independent risk factor for heart failure. Disruption of mitochondrial protein homeostasis plays a key role in pathological cardiac hypertrophy; however, the mechanism of maintaining mitochondrial homeostasis in pathological cardiac hypertrophy remains unclear. In this study, we investigated the regulatory mechanisms of mitochondrial protein homeostasis in pathological cardiac hypertrophy. Wildtype (WT) mice, knockout mice, and mice transfected with lentivirus overexpressing mouse C1q-tumor necrosis factor-related protein-3 (CTRP3) underwent transverse aortic constriction or sham surgery. After 4 weeks, cardiac function, mitochondrial function, and oxidative stress injury were examined. For mechanistic studies, neonatal rat cardiomyocytes were treated with small interfering RNA or overexpression plasmids for the relevant genes. CTRP3 overexpression attenuated transverse aortic constriction (TAC) induced pathological cardiac hypertrophy, mitochondrial dysfunction, and oxidative stress injury compared to that in WT mice. TAC or Ang II resulted in compensatory activation of UPRmt, but this was not sufficient to counteract pathologic cardiac hypertrophy. CTRP3 overexpression further induced activation of UPRmt during pathologic cardiac hypertrophy and thereby alleviated pathologic cardiac hypertrophy, whereas CTRP3 knockout or knockdown inhibited UPRmt. ATF5 was a key regulatory molecule of UPRmt, as ATF5 knockout prevented the cardioprotective effect of CTRP3 in TAC mice. In vitro, SIRT1 was identified as a possible downstream CTRP3 effector molecule, and SIRT1 knockout blocked the cardioprotective effects of CTRP3. Our results also suggest that ATF5 may be regulated by SIRT1. Our study demonstrates that CTRP3 activates UPRmt via the SIRT1/ATF5 axis under pathological myocardial hypertrophy, thus attenuating mitochondrial dysfunction and oxidative stress injury.

IFITM3 overexpression reverses insufficient healing benefits of small extracellular vesicles from high-fat-diet BMSCs in sepsis via the HMGB1 pathway.

Bone marrow mesenchymal stem cells (BMSCs) are a promising new therapy for sepsis, a common cause of death in hospitals. However, the global epidemic of metabolic syndromes, including obesity and pre-obesity, threatens the health of the human BMSC pool. The therapeutic effects of BMSCs are primarily due to the secretion of the small extracellular vesicles containing lipids, proteins, and RNA. Accordingly, studies on BMSCs, their small extracellular vesicles, and their modifications in obese individuals are becoming increasingly important. In this study, we investigated the therapeutic potential of small extracellular vesicles (sEVs) from high-fat diet BMSCs (sEVsHFD) in sepsis-induced liver-heart axis injury. We found that sEVsHFD yielded diminished therapeutic benefits compared to sEVs from chow diet BMSCs (sEVsCD). We subsequently verified that IFITM3 significantly differed in sEVsCD and sEVsHFD, alternating in septic liver tissue, and indicating its potential as a remodeling target of sEVs. IFITM3-overexpressed high-fat-diet BMSCs (HFD-BMSCs) showed that corresponding sEVs (sEVsHFD-IFITM3) markedly ameliorated liver-heart axis injury during sepsis. Lastly, we identified the protective action mechanisms of sEVsHFD-IFITM3 in sepsis-induced organ failure and HMGB1 expression and secretion was altered in septic liver and serum while HMGB1 has been demonstrated as a critical mediator of multi-organ failure in sepsis. These findings indicate that IFITM3 overexpression regenerates the therapeutic benefit of sEVs from HFD-BMSCs in sepsis via the HMGB1 pathway.

Crosstalk between macrophages and cardiac cells after myocardial infarction.

Cardiovascular diseases, such as myocardial infarction (MI), are a leading cause of death worldwide. Acute MI (AMI) inflicts massive injury to the coronary microcirculation, causing large-scale cardiomyocyte death due to ischemia and hypoxia. Inflammatory cells such as monocytes and macrophages migrate to the damaged area to clear away dead cells post-MI. Macrophages are pleiotropic cells of the innate immune system, which play an essential role in the initial inflammatory response that occurs following MI, inducing subsequent damage and facilitating recovery. Besides their recognized role within the immune response, macrophages participate in crosstalk with other cells (including cardiomyocytes, fibroblasts, immune cells, and vascular endothelial cells) to coordinate post-MI processes within cardiac tissue. Macrophage-secreted exosomes have recently attracted increasing attention, which has led to a more elaborate understanding of macrophage function. Currently, the functional roles of macrophages in the microenvironment of the infarcted heart, particularly with regard to their interaction with surrounding cells, remain unclear. Understanding the specific mechanisms that mediate this crosstalk is essential in treating MI. In this review, we discuss the origin of macrophages, changes in their distribution post-MI, phenotypic and functional plasticity, as well as the specific signaling pathways involved, with a focus on the crosstalk with other cells in the heart. Thus, we provide a new perspective on the treatment of MI. Further in-depth research is required to elucidate the mechanisms underlying crosstalk between macrophages and other cells within cardiac tissue for the identification of potential therapeutic targets. Video Abstract.

GLUT4 mediates the protective function of gastrodin against pressure overload-induced cardiac hypertrophy.

Gastrodia elata exhibits extensive pharmacological activity; its extract gastrodin (GAS) has been used clinically to treat cardiovascular diseases. In the present study, we examined the effect of GAS in a mice model of pathological cardiac hypertrophy, which was induced using transverse aortic constriction (TAC). Male C57BL/6 J mice underwent either TAC or sham surgery. GAS was administered post-surgically for 6 weeks and significantly improved the deterioration of cardiac contractile function caused by pressure overload, cardiac hypertrophy, and fibrosis in mice. Treatment with GAS for 6 weeks upregulated myosin heavy chain α and down-regulated myosin heavy chain ß and atrial natriuretic peptide, while insulin increased the effects of GAS against cardiac hypertrophy. In vitro studies showed that GAS could also protect phenylephrine-induced cardiomyocyte hypertrophy, and these effects were attenuated by BAY-876, and increased by insulin. Taken together, our results suggest that the anti-hypertrophic effect of gastrodin depends on its entry into cardiomyocytes through GLUT4.