SRV2 promotes mitochondrial fission and Mst1-Drp1 signaling in LPS-induced septic cardiomyopathy

Cortistatin protects against septic cardiomyopathy by inhibiting cardiomyocyte pyroptosis through the SSTR2-AMPK-NLRP3 pathway

BACKGROUND

Although the pathophysiological mechanism of septic cardiomyopathy has been continuously discovered, it is still a lack of effective treatment method. Cortistatin (CST), a neuroendocrine polypeptide of the somatostatin family, has emerged as a novel cardiovascular-protective peptide, but the specific mechanism has not been elucidated.

PURPOSE

The aim of our study is to explore the role of CST in cardiomyocytes pyroptosis and myocardial injury in sepsis and whether CST inhibits cardiomyocytes pyroptosis through specific binding with somastatin receptor 2 (SSTR2) and activating AMPK/Drp1 signaling pathway.

METHODS AND RESULTS

In this study, plasma CST levels were significantly high and were negatively correlated with N-terminal pro-B type natriuretic peptide (NT-proBNP), a biomarker for cardiac dysfunction, in patients with sepsis. Exogenous administration of CST significantly improved survival rate and cardiac function in mouse models of sepsis by inhibiting the activation of the NLRP3 inflammasome and pyroptosis of cardiomyocytes (decreased cleavage of caspase-1, IL-1β and gasdermin D). Pharmacological inhibition and genetic ablation revealed that CST exerted anti-pyroptosis effects by specifically binding to somatostatin receptor subtype 2 (SSTR2), thus activating AMPK and inactivating Drp1 to inhibit mitochondrial fission in cardiomyocytes.

CONCLUSIONS

This study is the first to report that CST attenuates septic cardiomyopathy by inhibiting cardiomyocyte pyroptosis through the SSTR2-AMPK-Drp1-NLRP3 pathway. Importantly, CST specifically binds to SSTR2, which promotes AMPK phosphorylation, inhibits Drp1-mediated mitochondrial fission, and reduces ROS levels, thereby inhibiting NLRP3 inflammasome activation-mediated pyroptosis and alleviating sepsis-induced myocardial injury.

Docosahexaenoic acid alleviates LPS-induced cytotoxicity in HL-1 cardiac cells via improving stress-induced mitochondrial fragmentation

Sepsis-induced cardiac injury is associated with oxidative stress and mitochondrial dysfunction. Docosahexaenoic acid (DHA), an essential omega-3 fatty acid, protects the injured myocardium by modulating mitochondrial dysfunction. We aimed to confirm whether the cardioprotective effect of DHA is mediated via the alleviation of mitochondrial fragmentation in lipopolysaccharide (LPS)-induced cardiomyopathy in vitro. We found that DHA improved cell viability and alleviated cardiac cell apoptosis by reducing lactate dehydrogenase (LDH) release, expression levels of Cleaved caspase-3, and Caspase 3 activity. DHA attenuated oxidative stress as evidenced by decreased ROS production and increased superoxide dismutase activity. In addition, DHA ameliorated mitochondrial dysfunction by modulating mitochondrial respiratory chain injury and mitochondrial fragmentation, especially decreasing the mitochondrial fission-related protein p-Drp1(ser 616) but no effects on Drp1, p-Drp1(ser 637), and mitochondrial fusion-related protein. Our data suggest that DHA conferred cardioprotection by alleviating oxidative stress-induced apoptosis, which may be associated with alleviation of stress-induced mitochondrial fragmentation.

MST1/2 in inflammation and immunity

The mammalian Sterile 20-like kinase 1/2 (MST1/2) belongs to the serine/threonine (GC) protein kinase superfamily. Collective studies confirm the vital role MST1/2 in inflammation and immunity. MST1/2 is closely related to the progress of inflammation. Generally, MST1/2 aggravates the inflammatory injury through MST1-JNK, MST1-mROS, MST1-Foxo3, and NF-κB pathways, as well as several regulatory factors such as tumor necrosis factor-α (TNF-α), mitochondrial extension factor 1 (MIEF1), and lipopolysaccharide (LPS). Moreover, MST1/2 is also involved in the regulation of immunity to balance immune activation and tolerance by regulating MST1/2-Rac, MST1-Akt1/c-myc, MST1-Foxos, MST1-STAT, Btk pathways, and lymphocyte function-related antigen 1 (LFA-1), which subsequently prevents immunodeficiency syndrome and autoimmune diseases. This article reviews the effects of MST1/2 on inflammation and immunity.

Cyclovirobuxine D pretreatment ameliorates septic heart injury through mitigation of ferroptosis

Myocardial dysfunction is a frequent complication in patients with severe sepsis. However, effective drugs for the prevention of myocardial dysfunction and the molecular mechanisms of the disease remain elusive. The present study demonstrated that Cyclovirobuxine D (CVB-D) could improve cardiac dysfunction in a cecal ligation and puncture (CLP) model in rodents and in a lipopolysaccharide (LPS) model in vitro. Echocardiography and histopathological examination were used to detect changes in cardiac structure and function. Kits were used to detect indicators of cardiac injury, transmission electron microscopy to detect structural changes in mitochondria and reverse transcription-quantitative PCR to detect prostaglandin-endoperoxide synthase 2 and hamp expression levels. L-Glutathione and malondialdehyde levels and superoxide dismutase activity were measured using kits. Cell viability was measured with the Cell Counting Kit-8. Iron metabolism-related proteins, inflammatory factor levels and related pathway proteins were detected using western blot analysis. Changes in L-type calcium currents were detected by membrane clamp, and contractility of cardiomyocytes was measured by Ion Optix. CVB-D attenuated CLP-induced cardiac malfunction in septic rats, with changes observed in myocardial pathological structure, creatine kinase isoenzyme (CK-MB), lactate dehydrogenase (LDH) and cardiac troponin I (cTnI). CVB-D attenuated sepsis-induced lipid peroxidation and iron overload. In addition, CVB-D decreased the expression of CK-MB, LDH and cTnI, suppressed oxidative stress index levels and reduced the production of reactive oxygen species. CVB-D decreased LPS-induced cytoplasmic iron overload by increasing upregulation of iron uptake molecules. Conversely, CVB-D significantly increased the upregulation of ferroportin 1. CVB-D pretreatment significantly reduced the levels of hamp mRNA compared with the LPS-treated group. CVB-D pretreatment significantly reduced inflammatory factor levels and the ratio of phosphorylated vs. total signal transducer and activator of transcription 3. The expression of SLC7A11 and GPX4 was upregulated in septic cells pretreated with CVB-D, however treatment with ML385 largely decreased this upregulation. Of note, CVB-D inhibited the inward flow of calcium ions through the LTCC. In conclusion, these findings suggest that CVB-D alleviated sepsis-induced cardiac iron toxicity by alleviating iron metabolism.

DUSP1 interacts with and dephosphorylates VCP to improve mitochondrial quality control against endotoxemia-induced myocardial dysfunction

Dual specificity phosphatase 1 (DUSP1) and valosin-containing protein (VCP) have both been reported to regulate mitochondrial homeostasis. However, their impact on mitochondrial quality control (MQC) and myocardial function during LPS-induced endotoxemia remains unclear. We addressed this issue by modeling LPS-induced endotoxemia in DUSP1 transgenic (DUSP1TG) mice and in cultured DUSP1-overexpressing HL-1 cardiomyocytes. Accompanying characteristic structural and functional deficits, cardiac DUSP1 expression was significantly downregulated following endotoxemia induction in wild type mice. In contrast, markedly reduced myocardial inflammation, cardiomyocyte apoptosis, cardiac structural disorder, cardiac injury marker levels, and normalized systolic/diastolic function were observed in DUSP1TG mice. Furthermore, DUSP1 overexpression in HL-1 cells significantly attenuated LPS-mediated mitochondrial dysfunction by preserving MQC, as indicated by normalized mitochondrial dynamics, improved mitophagy, enhanced biogenesis, and attenuated mitochondrial unfolded protein response. Molecular assays showed that VCP was a substrate of DUSP1 and the interaction between DUSP1 and VCP primarily occurred on the mitochondria. Mechanistically, DUSP1 phosphatase domain promoted the physiological DUSP1/VCP interaction which prevented LPS-mediated VCP Ser784 phosphorylation. Accordingly, transfection with a phosphomimetic VCP mutant abolished the protective actions of DUSP1 on MQC and aggravated inflammation, apoptosis, and contractility/relaxation capacity in HL-1 cardiomyocytes. These findings support the involvement of the novel DUSP1/VCP/MQC pathway in the pathogenesis of endotoxemia-caused myocardial dysfunction.

MST1: A future novel target for cardiac diseases

Major heart diseases pose a serious threat to human health. Finding early diagnostic markers and key therapeutic targets is an urgent scientific problem in this field. Mammalian sterile 20-like kinase 1 (MST1) is a protein kinase, and the occurrence of many heart diseases is related to the continuous activation of the MST1 gene. With the deepening of the research, the potential role of MST1 in promoting the development of heart disease has become more apparent. Therefore, to better understand the role of MST1 in the pathogenesis of heart disease, this work systematically summarizes the role of MST1 in the pathogenesis of heart disease, gives a comprehensive overview of its possible strategies in the diagnosis and treatment of heart disease, and analyzes its potential significance as a marker for the diagnosis and treatment of heart disease.

TMBIM6 prevents VDAC1 multimerization and improves mitochondrial quality control to reduce sepsis-related myocardial injury

BACKGROUND

The regulatory mechanisms involved in mitochondrial quality control (MQC) dysfunction during septic cardiomyopathy (SCM) remain incompletely characterized. Transmembrane BAX inhibitor motif containing 6 (TMBIM6) is an endoplasmic reticulum protein with Ca²⁺ leak activity that modulates cellular responses to various cellular stressors.

METHODS

In this study, we evaluated the role of TMBIM6 in SCM using cardiomyocyte-specific TMBIM6 knockout (TMBIM6^CKO) and TMBIM6 transgenic (TMBIM6^TG) mice.

RESULTS

Myocardial TMBIM6 transcription and expression were significantly downregulated in wild-type mice upon LPS exposure, along with characteristic alterations in myocardial systolic/diastolic function, cardiac inflammation, and cardiomyocyte death. Notably, these alterations were further exacerbated in LPS-treated TMBIM6^CKO mice, and largely absent in TMBIM6^TG mice. In LPS-treated primary cardiomyocytes, TMBIM6 deficiency further impaired mitochondrial respiration and ATP production, while defective MQC was suggested by enhanced mitochondrial fission, impaired mitophagy, and disrupted mitochondrial biogenesis. Structural protein analysis, Co-IP, mutant TMBIM6 plasmid transfection, and molecular docking assays subsequently indicated that TMBIM6 exerts cardioprotection against LPS-induced sepsis by interacting with and preventing the oligomerization of voltage-dependent anion channel-1 (VDAC1), the major route of mitochondrial Ca²⁺ uptake.

CONCLUSION

We conclude that the TMBIM6-VDAC1 interaction prevents VDAC1 oligomerization and thus sustains mitochondrial Ca²⁺ homeostasis as well as MQC, contributing to improved myocardial function in SCM.

Verbascoside protects from LPS-induced septic cardiomyopathy via alleviating cardiac inflammation, oxidative stress and regulating mitochondrial dynamics

BACKGROUND

Verbascoside (VB), as an active component of multiple medicinal plants, has been proved to exert anti-oxidative, anti-aging and neuroprotective effects. This study was designed to investigate whether VB could play a cardioprotective role in septic heart injury.

METHODS

Mice were injected with lipopolysaccharide (LPS; 10 mg/kg) to induce sepsis. The treatment group received an intraperitoneally injection of VB (20 mg/kg) before LPS challenge. Transthoracic echocardiography, ELISA, immunofluorescence, and qPCR were performed to assess the effect of VB on heart function, oxidative stress, inflammation and apoptosis. Transmission electronic microscopy and immunoblotting were used to evaluate the mitochondrial morphology and biogenesis of the septic heart. In vitro experiments were also performed to repeat above-mentioned assays.

RESULTS

Compared with LPS group, the VB treatment group showed improved cardiac function in sepsis. VB alleviated oxidative stress and inflammatory cell infiltration, as well as cardiomyocyte apoptosis. Specifically, VB could restore sepsis-induced mitochondrial alterations via regulating mitochondrial biogenesis. These results were also confirmed in in vitro experiments.

CONCLUSION

Verbascoside could protected from sepsis-induced cardiomyopathy by inhibiting oxidative stress, inflammation, and apoptosis, as well as promoting mitochondrial biogenesis.

Advances in Cardiotoxicity Induced by Altered Mitochondrial Dynamics and Mitophagy

Mitochondria are the most abundant organelles in cardiac cells, and are essential to maintain the normal cardiac function, which requires mitochondrial dynamics and mitophagy to ensure the stability of mitochondrial quantity and quality. When mitochondria are affected by continuous injury factors, the balance between mitochondrial dynamics and mitophagy is broken. Aging and damaged mitochondria cannot be completely removed in cardiac cells, resulting in energy supply disorder and accumulation of toxic substances in cardiac cells, resulting in cardiac damage and cardiotoxicity. This paper summarizes the specific underlying mechanisms by which various adverse factors interfere with mitochondrial dynamics and mitophagy to produce cardiotoxicity and emphasizes the crucial role of oxidative stress in mitophagy. This review aims to provide fresh ideas for the prevention and treatment of cardiotoxicity induced by altered mitochondrial dynamics and mitophagy.

MiR-141 attenuates sepsis-induced cardiomyopathy by targeting DAPK1

OBJECTIVE

To discuss the possible effects of microRNA-141 (miR-141) in sepsis-induced cardiomyopathy (SIC) via targeting death-associated protein kinase 1 (DAPK1).

METHODS

An SIC mouse model was constructed by abdominal injection of lipopolysaccharide (LPS) and divided into control, LPS, LPS + pre-miR-141, and LPS + anti-miR-141 groups. Hemodynamic indicators and heart function indexes of mice were detected. ELISA was used to determine the serum levels of inflammatory cytokines, while TUNEL staining to observe the apoptosis of myocardial cells of mice, as well as qRT-PCR and Western blotting to clarify the expression of miR-141 and DAPK1. Lastly, in vitro experiment was also conducted on the primary neonatal rat ventricular cardiomyocytes (NRVCMs) to validate the results.

RESULTS

Mice in the LPS group, as compared to the control group, had lower left ventricular ejection fraction, left ventricular fractional shortening, left ventricular systolic pressure, and ±dp/dt, but a higher left ventricular end-diastolic pressure, while the serum expression of IL-1β, IL-6, TNF-α, and cTn-T was up-regulated evidently with the increased apoptotic index of myocardial tissues. However, miR-141 and Bcl-2/Bax were down-regulated with elevated DAPK1 and cleaved caspase-3. The above changes were ameliorated in mice from the LPS + pre-miR-141 group relative to the LPS group, while those in the LPS + anti-miR-141 group were further deteriorated. In vitro experiment showed that miR-141 overexpression could reduce the apoptosis of LPS-induced NRVCMs and the levels of inflammatory cytokines with the increased cell viability.

CONCLUSION

MiR-141 could decrease inflammatory response and reduce myocardial cell apoptosis by targeting DAPK1, thereby playing the promising protective role in SIC.