Mitochondrial Mechanisms in Septic Cardiomyopathy

HGF ameliorates cardiomyocyte apoptosis and inflammatory response in sepsis via the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway

OBJECTIVE

This study aimed to analyze the impact of HGF on cardiomyocyte injury, apoptosis, and inflammatory response induced by lipopolysaccharide (LPS).

METHODS

Enzyme-linked immunosorbent assay (ELISA) was utilized to quantify the levels of HGF, interleukin (IL)-6, IL-10, creatine phosphokinase-isoenzyme-MB (CK-MB), and cardiac troponin I (cTnI) in the samples. qPCR and Western blotting (WB) were employed to assess the mRNA and protein expressions of HGF, IL-10, IL-6, PI3K, AKT, p-PI3K, and p-AKT.

RESULTS

The outcomes of the in vivo experiment revealed that serum levels of IL-6, IL-10, HGF and SOFA scores in the SC group were elevated in contrast to the non-SC group. The correlation analysis indicated a substantial and positive association among serum HGF, IL-6, and IL-10 levels and SOFA scores. Relative to IL-6, IL-10 levels, and SOFA scores, serum HGF demonstrated the highest diagnostic value for SC. Following LPS administration to stimulate H9c2 cells across various periods (0, 12, 24, 48, and 72 h), the levels of myocardial injury markers (CK-MB and cTnI) in the cell supernatants, intracellular inflammatory factors (mRNA and protein levels of IL-10 and IL-6), apoptosis and ROS levels, exhibited a gradual increase followed by a subsequent decline. Following the overexpression of HGF, there was an increase in cell viability, and a decrease in apoptosis, inflammation, oxidative stress injuries, and the protein phosphorylation expressions of PI3K and AKT. After knockdown of HGF expression, the activity of LPS-induced H9c2 cells was further reduced, leading to increased cell injury, apoptosis, inflammation, oxidative stress,and the expression levels of PI3K and Akt protein phosphorylation were further elevated.

CONCLUSION

HGF was associated with decreased LPS-induced H9c2 apoptosis and inflammation in H9c2 cells, alongside an improvement in cell viability, indicating potential cytoprotective effects. The mechanism underlying these impacts may be ascribed to the suppression of the PI3K/AKT signaling pathway.

Oxycodone attenuates lipopolysaccharide-induced myocardial injury by inhibiting inflammation, oxidation and pyroptosis via Nrf2/HO-1 signalling pathway

Myocardial injury and cardiovascular dysfunction are the most common complications of sepsis, and effective therapeutic candidate is still lacking. This study aims to investigate the protective effect of oxycodone in myocardial injury of lipopolysaccharide-induced sepsis and its related signalling pathways. Wild-type and nuclear factor erythroid 2-related factor 2 (Nrf2)-knockout mice, as well as H9c2 cardiomyocytes cultures treated with lipopolysaccharide (LPS) were used as models of septic myocardial injury. H9c2 cardiomyocytes culture showed that oxycodone protected cells from pyroptosis induced by LPS. Mice model confirmed that oxycodone pretreatment significantly attenuated myocardial pathological damage and improved cardiac function demonstrated by increased ejection fraction (EF) and fractional shortening (FS), as well as decreased cardiac troponin I (cTnI) and creatine kinase isoenzymes MB (CK-MB). Oxycodone also reduced the levels of inflammatory factors and oxidative stress damage induced by LPS, which involves pyroptosis-related proteins including: Nod-like receptor protein 3 (NLRP3), Caspase 1, Apoptosis-associated speck-like protein contain a CARD (ASC), and Gasdermin D (GSDMD). These changes were mediated by Nrf2 and heme oxygenase-1 (HO-1) because Nrf2-knockout mice or Nrf2 knockdown in H9c2 cells significantly reversed the beneficial effect of oxycodone on oxidative stress, inflammatory responses and NLRP3-mediated pyroptosis. Our findings yielded that oxycodone therapy reduces LPS-induced myocardial injury by suppressing NLRP3-mediated pyroptosis via the Nrf2/HO-1 signalling pathway in vivo and in vitro.

Melatonin regulates mitochondrial dynamics and mitophagy: Cardiovascular protection

Despite extensive progress in the knowledge and understanding of cardiovascular diseases and significant advances in pharmacological treatments and procedural interventions, cardiovascular diseases (CVD) remain the leading cause of death globally. Mitochondrial dynamics refers to the repetitive cycle of fission and fusion of the mitochondrial network. Fission and fusion balance regulate mitochondrial shape and influence physiology, quality and homeostasis. Mitophagy is a process that eliminates aberrant mitochondria. Melatonin (Mel) is a pineal-synthesized hormone with a range of pharmacological properties. Numerous nonclinical trials have demonstrated that Mel provides cardioprotection against ischemia/reperfusion, cardiomyopathies, atherosclerosis and cardiotoxicity. Recently, interest has grown in how mitochondrial dynamics contribute to melatonin cardioprotective effects. This review assesses the literature on the protective effects of Mel against CVD via the regulation of mitochondrial dynamics and mitophagy in both in-vivo and in-vitro studies. The signalling pathways underlying its cardioprotective effects were reviewed. Mel modulated mitochondrial dynamics and mitophagy proteins by upregulation of mitofusin, inhibition of DRP1 and regulation of mitophagy-related proteins. The evidence supports a significant role of Mel in mitochondrial dynamics and mitophagy quality control in CVD.

Progress of heparanase in septic cardiomyopathy: A review

Septic cardiomyopathy (SCM) is a severe complication caused by sepsis, resulting in a high mortality rate. The current understanding of the pathogenic mechanism of SCM primarily involves endocardial injury, microcirculation disturbance, mitochondrial dysfunction and fibrosis. Heparanase (HPA), an endo-β-D-glucuronidase, has been implicated in inflammation, immune response, coagulation promotion, microcirculation disturbance, mitochondrial dysfunction and fibrosis. Therefore, it was hypothesized that HPA may play an important role in the pathogenesis of SCM. The present study provides a summary of various pathophysiological changes and mechanisms behind the involvement of HPA in SCM. It also presents a novel perspective on the pathogenic mechanism, diagnosis and treatment of SCM.

ANXA1sp modulates the protective effect of Sirt3-induced mitophagy against sepsis-induced myocardial injury in mice

AIM

Sepsis-induced myocardial injury (SIMI) may be associated with insufficient mitophagy in cardiomyocytes, but the exact mechanism involved remains unknown. Sirtuin 3 (Sirt3) is mainly found in the mitochondrial matrix and is involved in repairing mitochondrial function through means such as the activation of autophagy. Previously, we demonstrated that the annexin-A1 small peptide (ANXA1sp) can promote Sirt3 expression in mitochondria. In this study, we hypothesized that the activation of Sirt3 by ANXA1sp induces mitophagy, thereby providing a protective effect against SIMI in mice.

METHODS

A mouse model of SIMI was established via cecal ligation and puncture. Intraperitoneal injections of ANXA1sp, 3TYP, and 3MA were administered prior to modeling. After successful modeling, IL-6, TNF-α, CK-MB, and CTn-I levels were measured; cardiac function was assessed using echocardiography; myocardial mitochondrial membrane potential, ROS, and ATP production were determined; myocardial mitochondrial ultrastructure was observed using transmission electron microscopy; and the expression levels of Sirt3 and autophagy-related proteins were detected using western blotting.

RESULTS

ANXA1sp significantly reduced serum IL-6, TNF-α, CK-MB, and CTn-I levels; decreased myocardial ROS production; increased mitochondrial membrane potential and ATP synthesis; and improved myocardial mitochondrial ultrastructure in septic mice. Furthermore, ANXA1sp promoted Sirt3 expression and activated the AMPK-mTOR pathway to induce myocardial mitophagy. These protective effects of ANXA1sp were reversed upon treatment with the Sirt3 blocker, 3-TYP.

CONCLUSION

ANXA1sp can reverse SIMI, and the underlying mechanism may be related to the activation of the AMPK-mTOR pathway following upregulation of Sirt3 by ANXA1sp, which, in turn, induces autophagy.

CytoSorb® in burn patients with septic shock and Acute Kidney Injury on Continuous Kidney Replacement Therapy is associated with improved clinical outcome and survival

BACKGROUND

In burn patients, septic shock and acute kidney injury (AKI) with use of continuous renal replacement therapy (CRRT) severely increase morbidity and mortality. Sorbent therapies could be an adjunctive therapy to address the underlying metabolic changes in inflammatory and anti-inflammatory cytokines dysregulated production.

METHODS

A retrospectively observational study of 35 severe burn patients admitted to the Burn Center (Turin, Italy, from January 2017 to December 2022), who underwent CRRT for AKI-associated septic shock. Out of 35 patients, 11 were treated with CytoSorb® as adjunctive therapy to CRRT (Sorbent group) and 24 patients only with CRRT (Control group).

RESULTS

The application of CytoSorb® took place in a very dispersed way. Out of 11 patients, 7 started the CRRT together with the sorbent application. The patients of the sorbent group exhibited a significant reduction in norepinephrine use compared to that of the control group. A clinical improvement over the first 4 days of Cytosorb® was observed in both survivors and no survivors of the sorbent group, with significant norepinephrine decreased use on day 4 compared to day 1. In-hospital mortality was 45.4% and 70.8% in the sorbent and control group, respectively, and significantly better at Kaplan-Meier survival analysis at 270 days (p = 0.0445). In both groups, all survivor patients recovered renal function at discharge, whereas no survivors did not.

CONCLUSIONS

Adjunctive treatment with CytoSorb® for burn patients with AKI-CRRT and septic shock poorly responsive to standard therapy led to a significant clinical improvement, and was associated with a lower mortality rate compared to CRRT alone.

BMAL1 alleviates myocardial damage in sepsis by activating SIRT1 signaling and promoting mitochondrial autophagy

BACKGROUND

Brain and muscle arnt-like protein-1 (BMAL1) deficiency is associated with myocardial dysfunction and suppressed sirtuin 1 (SIRT1). However, whether BMAL1 promotes mitophagy via SIRT1 to alleviate myocardial injury in sepsis remains unknown.

METHODS

An in vitro myocardial injury model was established using lipopolysaccharide (LPS)-treated H9C2 cells. Knockdown or overexpression of genes was performed using plasmid transfection. Gene and protein expression was assessed by qRT-PCR and Western blot, respectively. Cell proliferation was evaluated using cell counting kit-8, and cellular apoptosis and reactive oxygen species (ROS) levels were analyzed using flow cytometry. An in vivo myocardial injury model of sepsis was established by cecal ligation and puncture in rats. Myocardial function was characterized by analyzing the damage-associated proteins, inflammatory factors, ejection fraction, and fraction shortening.

RESULTS

sgBMAL1 significantly decreased BMAL1 levels and remarkably increased the sensitivity of H9C2 cells to LPS stimulation, consequently enhancing LPS-induced apoptosis, inflammation, and ROS levels. These effects were further attenuated by BMAL1 overexpression. BMAL1 knockdown inhibited the expression of SIRT1 and mitophagy-associated proteins. SIRT1 overexpression reversed the enhancement of shBMAL1 on cell proliferation and inflammation. In the rat model of sepsis, BMAL1 overexpression decreased the myocardial injury-associated proteins to recover the myocardial function and suppressed inflammatory activities by promoting mitophagy via SIRT1.

CONCLUSION

BMAL1 enhances mitophagy dependent on SIRT1, thereby alleviating myocardial injury in sepsis.

2,4'-Dihydroxybenzophenone: A Promising Anti-Inflammatory Agent Targeting Toll-like Receptor 4/Myeloid Differentiation Factor 2-Mediated Mitochondrial Reactive Oxygen Species Production during Lipopolysaccharide-Induced Systemic Inflammation

The biochemical properties of 2,4'-dihydroxybenzophenone (DHP) have not been extensively studied. Therefore, this study aimed to investigate whether DHP could alleviate inflammatory responses induced by lipopolysaccharide (LPS) and endotoxemia. The results indicated that DHP effectively reduced mortality and morphological abnormalities, restored heart rate, and mitigated macrophage and neutrophil recruitment to inflammatory sites in LPS-microinjected zebrafish larvae. Additionally, the expression of pro-inflammatory mediators, including inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), and interleukin-12 (IL-12), was significantly reduced in the presence of DHP. In RAW 264.7 macrophages, DHP inhibited the LPS-induced inflammatory response by downregulating pro-inflammatory mediators and decreasing the expression of myeloid differentiation primary response 88 (MyD88), phosphorylation of IL-1 receptor-associated protein kinase-4 (p-IRAK4), and nuclear factor-κB (NF-κB). Molecular docking analysis demonstrated that DHP occupies the hydrophobic pocket of myeloid differentiation factor 2 (MD2) and blocks the dimerization of Toll-like receptor 4 (TLR4). A molecular dynamics simulation confirmed that DHP stably bound to the hydrophobic pocket of MD2. Furthermore, the DHP treatment inhibited mitochondrial reactive oxygen species (mtROS) production during the LPS-induced inflammatory response in both RAW 264.7 macrophages and zebrafish larvae, which was accompanied by stabilizing mitochondrial membrane potential. In conclusion, our study highlights the therapeutic potential of DHP in alleviating LPS-induced inflammation and endotoxemia. The findings suggest that DHP exerts its anti-inflammatory effects by inhibiting the TLR4/MD2 signaling pathway and reducing the level of mtROS production. These results contribute to a better understanding of the biochemical properties of DHP and support its further exploration as a potential therapeutic agent for inflammatory conditions and endotoxemia.

Sepsis increases the risk of in-hospital cardiac arrest: a population-based analysis

Sepsis patients have a high risk of developing in-hospital cardiac arrest (IHCA), which portends poor survival. However, little is known about whether the increased incidence of IHCA is due to sepsis itself or to comorbidities harbored by sepsis patients. We conducted a retrospective population-based cohort study comprising 20,022 patients admitted with sepsis to hospitals in Taiwan using the National Health Insurance Research Database (NHIRD). We constructed three non-sepsis comparison cohorts using risk set sampling and propensity score (PS) matching. We used univariate conditional logistic regression to evaluate the risk of IHCA and associated mortality. We identified 12,790 inpatients without infection (matched cohort 1), 12,789 inpatients with infection but without sepsis (matched cohort 2), and 10,536 inpatients with end-organ dysfunction but without sepsis (matched cohort 3). In the three PS-matched cohorts, the odds ratios (OR) for developing ICHA were 21.17 (95% CI 17.19, 26.06), 18.96 (95% CI: 15.56, 23.10), and 1.23 (95% CI: 1.13, 1.33), respectively (p < 0.001 for all ORs). In conclusion, in our study of inpatients across Taiwan, sepsis was independently associated with an increased risk of IHCA. Further studies should focus on identifying the proxy causes of IHCA using real-time monitoring data to further reduce the incidence of cardiopulmonary insufficiency in patients with sepsis.

The DNA-dependent protein kinase catalytic subunit promotes sepsis-induced cardiac dysfunction through disrupting INF-2-dependent mitochondrial dynamics

Sepsis-induced cardiomyopathy (SIC) represents a severe complication of systemic infection, characterized by significant cardiac dysfunction. This study examines the role of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and Inverted Formin 2 (INF2) in the pathogenesis of SIC, focusing on their impact on mitochondrial homeostasis and dynamics. Our research demonstrates that silencing DNA-PKcs alleviates lipopolysaccharide (LPS)-induced cardiomyocyte death and dysfunction. Using HL-1 cardiomyocytes treated with LPS, we observed that DNA-PKcs knockdown notably reverses LPS-induced cytotoxicity, indicating a protective role against cellular damage. This effect is further substantiated by the reduction in caspase-3 and caspase-9 activation, key markers of apoptosis, upon DNA-PKcs knockdown. Besides, our data further reveal that DNA-PKcs knockdown attenuates LPS-induced mitochondrial dysfunction, evidenced by improved ATP production, enhanced activities of mitochondrial respiratory complexes, and preserved mitochondrial membrane potential. Moreover, DNA-PKcs deletion counteracts LPS-induced shifts towards mitochondrial fission, indicating its regulatory influence on mitochondrial dynamics. Conclusively, our research elucidates the intricate interplay between DNA-PKcs and INF2 in the modulation of mitochondrial function and dynamics during sepsis-induced cardiomyopathy. These findings offer new insights into the molecular mechanisms underpinning SIC and suggest potential therapeutic targets for mitigating mitochondrial dysfunction in this critical condition.

Targeting ferroptosis in the maintenance of mitochondrial homeostasis in the realm of septic cardiomyopathy

Septic cardiomyopathy is one of the predominant culprit factors contributing to the rising mortality in patients with severe sepsis. Among various mechanisms responsible for the etiology of septic heart anomalies, disruption of mitochondrial homeostasis has gained much recent attention, resulting in myocardial inflammation and even cell death. Ferroptosis is a novel category of regulated cell death (RCD) provoked by iron-dependent phospholipid peroxidation through iron-mediated phospholipid (PL) peroxidation, enroute to the rupture of plasma membranes and eventually cell death. This review summarizes the recent progress of ferroptosis in mitochondrial homeostasis during septic cardiomyopathy. We will emphasize the role of mitochondrial iron transport channels and the antioxidant system in ferroptosis. Finally, we will summarize and discuss future research, which should help guide disease treatment.

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.

Sepsis‑induced cardiac dysfunction and pathogenetic mechanisms (Review)

Sepsis is a manifestation of the immune and inflammatory response to infection, which may lead to multi‑organ failure. Health care advances have improved outcomes in critical illness, but it still remains the leading cause of death. Septic cardiomyopathy is heart dysfunction brought on by sepsis. Septic cardiomyopathy is a common consequence of sepsis and has a mortality rate of up to 70%. There is a lack of understanding of septic cardiomyopathy pathogenesis; knowledge of its pathogenesis and the identification of potential therapeutic targets may reduce the mortality rate of patients with sepsis and lead to clinical improvements. The present review aimed to summarize advances in the pathogenesis of cardiac dysfunction in sepsis, with a focus on mitochondrial dysfunction, metabolic changes and cell death modalities and pathways. The present review summarized diagnostic criteria and outlook for sepsis treatment, with the goal of identifying appropriate treatment methods for this disease.

Design and synthesis of salidroside analogs and their bioactivity against septic myocardial injury

Cardiac tissue suffers much from sepsis, and the incidence of myocardial injury is high in septic patients. The treatment of sepsis myocardial injury (SMI) has been the focus of clinical medicine. Salidroside shows myocardial cell protection, anti-oxidation and anti- inflammation effects, and it is thought as one of the potential compounds to treat sepsis myocardial injury. However, its anti-inflammatory activity is lower and its pharmacokinetic properties are not ideal, which is far from clinical application. Here, a series of salidroside analogs were synthesized, and their bioactivities were evaluated from several aspects, including their anti-oxidant and anti-inflammatory activities in vitro and anti-sepsis myocardial injury activities in vivo. Of all the compounds which synthesized, compounds 2 and 3 exhibited stronger anti-inflammatory activities than the others; after treating LPS-stimulated RAW264.7 or H9c2 cells with each of them, the levels of IL-1β, IL-6 and TNF-α were down-regulated in a dose-dependent manner. In the anti-oxidative stress injury test, compounds 2 and 3 not only markedly increased the survival rate of cells, and but also improved the cellular oxidative stress-related indicators MDA, SOD and cell damage marker LDH in a dose-dependent manner. In the LPS-induced septic rat myocardial injury models (in vivo), the two compounds also showed good bioactivities. They also reduced the expression of IL-1β, IL-6 and TNF-α, and blocked cell damage by suppressing overhauled oxidation in septic rats. In addition, the myocardial injury was significantly improved and the inflammatory infiltration was reduced after treatment with the two compounds. In conclusion, the salidroside analogs (2 and 3) showed promising therapeutical effect on septic myocardial injury in LPS-model rats, and they could be good candidates for clinical trials against inflammation and septic myocardial injury.

Lipid oxidation dysregulation: an emerging player in the pathophysiology of sepsis

Sepsis is a life-threatening organ dysfunction caused by abnormal host response to infection. Millions of people are affected annually worldwide. Derangement of the inflammatory response is crucial in sepsis pathogenesis. However, metabolic, coagulation, and thermoregulatory alterations also occur in patients with sepsis. Fatty acid mobilization and oxidation changes may assume the role of a protagonist in sepsis pathogenesis. Lipid oxidation and free fatty acids (FFAs) are potentially valuable markers for sepsis diagnosis and prognosis. Herein, we discuss inflammatory and metabolic dysfunction during sepsis, focusing on fatty acid oxidation (FAO) alterations in the liver and muscle (skeletal and cardiac) and their implications in sepsis development.

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.

RIGHT VENTRICULAR DYSFUNCTION IN SEPSIS: AN UPDATED NARRATIVE REVIEW

ABSTRACT

Sepsis is a multisystem disease process, which constitutes a significant public health challenge and is associated with high morbidity and mortality. Among other systems, sepsis is known to affect the cardiovascular system, which may manifest as myocardial injury, arrhythmias, refractory shock, and/or septic cardiomyopathy. Septic cardiomyopathy is defined as the reversible systolic and/or diastolic dysfunction of one or both ventricles. Left ventricle dysfunction has been extensively studied in the past, and its prognostic role in patients with sepsis is well documented. However, there is relatively scarce literature on right ventricle (RV) dysfunction and its role. Given the importance of timely detection of septic cardiomyopathy and its bearing on prognosis of patients, the role of RV dysfunction has come into renewed focus. Hence, through this review, we sought to describe the pathophysiology of RV dysfunction in sepsis and what have we learnt so far about its multifactorial nature. We also elucidate the roles of different biomarkers for its detection and prognosis, along with appropriate management of such patient population.

MECHANISMS OF CARDIAC DYSFUNCTION IN SEPSIS

ABSTRACT

Studies in animal models of sepsis have elucidated an intricate network of signaling pathways that lead to the dysregulation of myocardial Ca 2+ handling and subsequently to a decrease in cardiac contractile force, in a sex- and model-dependent manner. After challenge with a lethal dose of LPS, male animals show a decrease in cellular Ca 2+ transients (ΔCa i ), with intact myofilament function, whereas female animals show myofilament dysfunction, with intact ΔCa i . Male mice challenged with a low, nonlethal dose of LPS also develop myofilament desensitization, with intact ΔCa i . In the cecal ligation and puncture (CLP) model, the causative mechanisms seem similar to those in the LPS model in male mice and are unknown in female subjects. ΔCa i decrease in male mice is primarily due to redox-dependent inhibition of sarco/endoplasmic reticulum Ca 2+ ATP-ase (SERCA). Reactive oxygen species (ROS) are overproduced by dysregulated mitochondria and the enzymes NADPH/NADH oxidase, cyclooxygenase, and xanthine oxidase. In addition to inhibiting SERCA, ROS amplify cardiomyocyte cytokine production and mitochondrial dysfunction, making the process self-propagating. In contrast, female animals may exhibit a natural redox resilience. Myofilament dysfunction is due to hyperphosphorylation of troponin I, troponin T cleavage by caspase-3, and overproduction of cGMP by NO-activated soluble guanylate cyclase. Depleted, dysfunctional, or uncoupled mitochondria likely synthesize less ATP in both sexes, but the role of energy deficit is not clear. NO produced by NO synthase (NOS)-3 and mitochondrial NOSs, protein kinases and phosphatases, the processes of autophagy and sarco/endoplasmic reticulum stress, and β-adrenergic insensitivity may also play currently uncertain roles.

Functional restoration of lysosomes and mitochondria through modulation of AKT activity ameliorates senescence

Senescence is a phenomenon defined by alterations in cellular organelles and is the primary cause of aging and aging-related diseases. Recent studies have shown that oncogene-induced senescence is driven by activation of serine/threonine protein kinases (AKT1, AKT2 and AKT3). In this study, we evaluated twelve AKT inhibitors and revealed GDC0068 as a potential agent to ameliorate senescence. Senescence-ameliorating effect was evident from the finding that GDC0068 yielded lysosomal functional recovery as observed by reduction in lysosomal mass and induction in autophagic flux. Furthermore, GDC0068-mediated restoration of lysosomal function activated the removal of dysfunctional mitochondria, resulting in restoration of mitochondrial function. Together, our findings revealed a unique mechanism by which senescence is recovered by functional restoration of lysosomes and mitochondria through modulation of AKT activity.

Shengmai san-derived compound prescriptions: A review on chemical constituents, pharmacokinetic studies, quality control, and pharmacological properties

BACKGROUND

Shengmai San Formula (SMS), composed of Ginseng Radix et Rhizoma, Ophiopogon Radix and Schisandra chinensis Fructus, was a famous formula in Tradition Chinese Medicine (TCM). With the expansion of clinical applications, SMS was developed to different dosage forms, including Shengmai Yin Oral liquid (SMY), Shengmai Capsule (SMC), Shengmai Granule (SMG), Shengmai Injection (SMI) and Dengzhan Shengmai Capsule (DZSMC). These above SMS-derived compound prescriptions (SSCPs) play an important role in the clinical treatment. This review is aimed to providing a comprehensive perspective of SSCP.

METHODS

The relevant literatures were collected from classical TCM books and a variety of databases, including PubMed, Google Scholar, Science Direct, Springer Link, Web of Science, China National Knowledge Infrastructure, and Wanfang Data.

RESULTS

The chemical constituents of SSCPs, arrived from the individual medicinal materials including Ginseng Radix et Rhizoma, Ophiopogon Radix, Schisandra chinensis Fructus, Erigerontis Herba, were firstly summarized respectively. Then the pharmacokinetics studies, quality control, and pharmacological properties of SSCPs were all reviewed. The active compounds, pharmacokinetics characterizes, quality control markers, the effects and mechanisms of pharmacology of the different dosage forms of SSCPs were summarized. Furthermore, the research deficiencies of SSCPs and an innovative research paradigm for Chinese materia medica (CMM) formula were proposed.

CONCLUSIONS

SMS, as a famous CMM formula, has great values in drug research and in clinical treatment especially for cardiocerebrovascular diseases. This article firstly make a comprehensive and systematic review on SMS.

Restoration of Lysosomal and Mitochondrial Function Through p38 Mitogen-Activated Protein Kinase Inhibition Ameliorates Senescence

Oncogene-induced senescence (OIS), characterized by irreversible cell cycle arrest by oncogene activation, plays an important role in the pathogenesis of aging and age-related diseases. Recent research indicates that OIS is driven by activation of mitogen-activated protein kinase (MAPK). However, it is not apparent whether MAPK inhibition helps to recover senescence. In our previous study, we uncovered p38 MAPK inhibitor, SB203580, as an effective agent to reduce reactive oxygen species and increase proliferation in premature senescent cells. In this study, we evaluated whether SB203580 could ameliorate senescence in normal senescent cells. The senescence-improving effect was observed in the results that SB203580 treatment restored lysosomal function, as evidenced by a decrease in lysosomal mass and an increase in autophagic vacuoles. Then, SB203580-mediated lysosomal function restoration triggered the clearance of damaged mitochondria, leading to metabolic reprogramming necessary for amelioration of senescence. Indeed, p38 MAPK inhibition by SB203580 improved key senescent phenotypes. Our findings suggest a novel mechanism by which modulation of p38 MAPK activity leads to senescence improvement through functional restoration of lysosome and mitochondria.

Exploration of the Shared Gene Signatures between Myocardium and Blood in Sepsis: Evidence from Bioinformatics Analysis

Background

Septic cardiomyopathy is widespread during sepsis and has adverse effects on mortality. Diagnosis of septic cardiomyopathy now mainly depends on transthoracic echocardiogram. Although some laboratory tests such as troponin T and atrial brain natriuretic peptide play a role in the diagnosis, specific blood biochemistry biomarkers are still lacking. Objective and Methods. In our study, we sought to find potential biological markers from genes and pathways that are covariant in the blood and myocardium of septic patients. Bioinformatics and machine learning methods were applied to achieve our goal. Datasets of myocardium and peripheral blood of patients with sepsis were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were selected and received functional enrichment analysis. Unsupervised hierarchical clustering analysis was performed to identify the subtypes of sepsis. Random forest, lasso regression, and logistic regression were used for variable screening and model construction. Internal and external validation sets were applied to verify the efficiency of the model in classifying disease and predicting mortality.

Results

By defining significance for genes using Student's t-test, we obtained 1,049 genes commonly changed in both myocardium and blood of patients with sepsis. The upregulated genes (LogFC >0) were related to inflammation pathways, and downregulated (LogFC <0) genes were related to mitochondrial and aerobic metabolism. We divided 468 sepsis patients into two groups with different clinical result based on the mortality-related commonly changed genes (104 genes), using unsupervised hierarchical clustering analysis. In our validation datasets, a six-gene model (SMU1, CLIC3, SP100, ARHGAP25, DECR1, and TNS3) was obtained and proven to perform well in classifying groups and predicting mortality.

Conclusion

We have identified genes that have the potential to become biomarkers for septic cardiomyopathy. Additionally, the pathophysiological changes in the myocardium of patients with sepsis were also reflected in peripheral blood to some extent. The co-occurring pathological processes can affect the prognosis of sepsis.

An Overview on Mitochondrial-Based Therapies in Sepsis-Related Myocardial Dysfunction: Mitochondrial Transplantation as a Promising Approach

Sepsis is defined as a life-threatening organ failure due to dysregulated host response to infection. Despite current advances in our knowledge about sepsis, it is still considered as a major global health challenge. Myocardial dysfunction is a well-defined manifestation of sepsis which is related to worse outcomes in septic patients. Given that the heart is a mitochondria-rich organ and the normal function of mitochondria is essential for successful modulation of septic response, the contribution of mitochondrial damage in sepsis-related myocardial dysfunction has attracted the attention of many scientists. It is widely accepted that mitochondrial damage is involved in sepsis-related myocardial dysfunction; however, effective and potential treatment modalities in clinical setting are still lacking. Mitochondrial-based therapies are potential approaches in sepsis treatment. Although various therapeutic strategies have been used for mitochondrial function improvement, their effects are limited when mitochondria undergo irreversible alterations under septic challenge. Therefore, application of more effective approaches such as mitochondrial transplantation has been suggested. This review highlights the crucial role of mitochondrial damage in sepsis-related myocardial dysfunction, then provides an overview on mitochondrial-based therapies and current approaches to mitochondrial transplantation as a novel strategy, and proposes future directions for more researches in this field.

Regulation of Oxidative Phosphorylation of Liver Mitochondria in Sepsis

The link between liver dysfunction and decreased mitochondrial oxidative phosphorylation in sepsis has been clearly established in experimental models. Energy transduction is plastic: the efficiency of mitochondrial coupling collapses in the early stage of sepsis but is expected to increase during the recovery phases of sepsis. Among the mechanisms regulating the coupling efficiency of hepatic mitochondria, the slipping reactions at the cytochrome oxidase and ATP synthase seem to be a determining element, whereas other regulatory mechanisms such as those involving proton leakage across the mitochondrial membrane have not yet been formally proven in the context of sepsis. If the dysfunction of hepatic mitochondria is related to impaired cytochrome c oxidase and ATP synthase functions, we need to consider therapeutic avenues to restore their activities for recovery from sepsis. In this review, we discussed previous findings regarding the regulatory mechanism involved in changes in the oxidative phosphorylation of liver mitochondria in sepsis, and propose therapeutic avenues to improve the functions of cytochrome c oxidase and ATP synthase in sepsis.

Pyruvate-Driven Oxidative Phosphorylation is Downregulated in Sepsis-Induced Cardiomyopathy: A Study of Mitochondrial Proteome

BACKGROUND

Sepsis-induced cardiomyopathy (SIC) is a major contributing factor for morbidity and mortality in sepsis. Accumulative evidence has suggested that cardiac mitochondrial oxidative phosphorylation is attenuated in sepsis, but the underlying molecular mechanisms remain incompletely understood.

METHODS

Adult male mice of 9 to 12 weeks old were subjected to sham or cecal ligation and puncture procedure. Echocardiography in vivo and Langendorff-perfused hearts were used to assess cardiac function 24 h after the procedures. Unbiased proteomics analysis was performed to profile mitochondrial proteins in the hearts of both sham and SIC mice. Seahorse respirator technology was used to evaluate oxygen consumption in purified mitochondria.

RESULTS

Of the 665 mitochondrial proteins identified in the proteomics assay, 35 were altered in septic mice. The mitochondrial remodeling involved various energy metabolism pathways including subunits of the electron transport chain, fatty acid catabolism, and carbohydrate oxidative metabolism. We also identified a significant increase of pyruvate dehydrogenase (PDH) kinase 4 (PDK4) and inhibition of PDH activity in septic hearts. Furthermore, compared to sham mice, mitochondrial oxygen consumption of septic mice was significantly reduced when pyruvate was provided as a substrate. However, it was unchanged when PDH was bypassed by directly supplying the Complex I substrate NADH, or by using the Complex II substrate succinate, or using Complex IV substrate, or by providing the beta-oxidation substrate palmitoylcarnitine, neither of which require PDH for mitochondrial oxygen consumption.

CONCLUSIONS

These data demonstrate a broad mitochondrial protein remodeling, PDH inactivation and impaired pyruvate-fueled oxidative phosphorylation during SIC, and provide a molecular framework for further exploration.

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.

MIAT, a potent CVD-promoting lncRNA

The initial identification of long non-coding RNA myocardial infarction associated transcript (MIAT) as a genetic risk factor of myocardial infarction has made this lncRNA (designated as lncR-MIAT here) a focus of intensive studies worldwide. Emerging evidence supports that lncR-MIAT is susceptible in its expression to multiple deleterious factors like angiotensin II, isoproterenol, hypoxia, and infection and is anomaly overexpressed in serum, plasma, blood cells and myocardial tissues under a variety of cardiovascular conditions including myocardial infarction, cardiac hypertrophy, diabetic cardiomyopathy, dilated cardiomyopathy, sepsis cardiomyopathy, atrial fibrillation and microvascular dysfunction. Experimental results consistently demonstrated that upregulation of lncR-MIAT plays active roles in the pathological processes of the cardiovascular system and knockdown of this lncRNA effectively ameliorates the adverse conditions. The available data revealed that lncR-MIAT acts through multiple mechanisms such as competitive endogenous RNA, natural antisense RNA and RNA/protein interactions. Moreover, the functional domains of lncR-MIAT accounting for certain specific cellular functions of the full-length transcript have been identified and characterized. These insights will not only tremendously advance our understanding of lncRNA biology and pathophysiology, but also offer good opportunities for more innovative and precise design of agents that have the potential to be developed into new drugs for better therapy of cardiovascular diseases (CVDs) in the future. Herein, we provide an overview of lncR-MIAT, focusing on its roles in cardiovascular diseases, underline the unique cellular/molecular mechanisms for its actions, and speculate the perspectives about the translational studies on the potential diagnostic and therapeutic applications of lncR-MIAT.

Roles of LncRNAs in Regulating Mitochondrial Dysfunction in Septic Cardiomyopathy

Sepsis is an abnormal systemic inflammatory response of the host immune system to infection and can lead to fatal multiorgan dysfunction syndrome. Epidemiological studies have shown that approximately 10-70% of sepsis cases can lead to septic cardiomyopathy. Since the pathogenesis of septic cardiomyopathy is not clear, it is difficult for medical doctors to treat the disease. Therefore, finding effective interventions to prevent and reduce myocardial damage in septic cardiomyopathy is clinically significant. Epigenetics is the study of stable genetic phenotype inheritance that does not involve changing gene sequences. Epigenetic inheritance is affected by both gene and environmental regulation. Epigenetic studies focus on the modification and influence of chromatin structure, mainly including chromatin remodelling, DNA methylation, histone modification and noncoding RNA (ncRNA)-related mechanisms. Recently, long ncRNA (lncRNA)-related mechanisms have been the focus of epigenetic studies. LncRNAs are expected to become important targets to prevent, diagnose and treat human diseases. As the energy metabolism centre of cells, mitochondria are important targets in septic cardiomyopathy. Intervention measures to prevent and treat mitochondrial damage are of great significance for improving the prognosis of septic cardiomyopathy. LncRNAs play important roles in life activities. Recently, studies have focused on the involvement of lncRNAs in regulating mitochondrial dysfunction. However, few studies have revealed the involvement of lncRNAs in regulating mitochondrial dysfunction in septic cardiomyopathy. In this article, we briefly review recent research in this area.

GSDMD Mediates LPS-Induced Septic Myocardial Dysfunction by Regulating ROS-dependent NLRP3 Inflammasome Activation

Myocardial dysfunction is a serious consequence of sepsis and contributes to high mortality. Currently, the molecular mechanism of myocardial dysfunction induced by sepsis remains unclear. In the present study, we investigated the role of gasdermin D (GSDMD) in cardiac dysfunction in septic mice and the underlying mechanism. C57BL/6 wild-type (WT) mice and age-matched Gsdmd-knockout (Gsdmd ^-/-) mice were intraperitoneally injected with lipopolysaccharide (LPS) (10 mg/kg) to mimic sepsis. The results showed that GSDMD-NT, the functional fragment of GSDMD, was upregulated in the heart tissue of septic WT mice induced by LPS, which was accompanied by decreased cardiac function and myocardial injury, as shown by decreased ejection fraction (EF) and fractional shortening (FS) and increased cardiac troponin I (cTnI), creatine kinase isoenzymes MB (CK-MB), and lactate dehydrogenase (LDH). Gsdmd ^-/- mice exhibited protection against LPS-induced myocardial dysfunction and had a higher survival rate. Gsdmd deficiency attenuated LPS-induced myocardial injury and cell death. Gsdmd deficiency prevented LPS-induced the increase of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in serum, as well as IL-1β and TNF-α mRNA levels in myocardium. In addition, LPS-mediated inflammatory cell infiltration into the myocardium was ameliorated and activation of NF-κB signaling pathway and the NOD-like receptor protein 3 (NLPR3) inflammasome were suppressed in Gsdmd ^-/- mice. Further research showed that in the myocardium of LPS-induced septic mice, GSDMD-NT enrichment in mitochondria led to mitochondrial dysfunction and reactive oxygen species (ROS) overproduction, which further regulated the activation of the NLRP3 inflammasome. In summary, our data suggest that GSDMD plays a vital role in the pathophysiology of LPS-induced myocardial dysfunction and may be a crucial target for the prevention and treatment of sepsis-induced myocardial dysfunction.

Targeting Mitochondrial Metabolism as a Strategy to Treat Senescence

Mitochondria are one of organelles that undergo significant changes associated with senescence. An increase in mitochondrial size is observed in senescent cells, and this increase is ascribed to the accumulation of dysfunctional mitochondria that generate excessive reactive oxygen species (ROS). Such dysfunctional mitochondria are prime targets for ROS-induced damage, which leads to the deterioration of oxidative phosphorylation and increased dependence on glycolysis as an energy source. Based on findings indicating that senescent cells exhibit mitochondrial metabolic alterations, a strategy to induce mitochondrial metabolic reprogramming has been proposed to treat aging and age-related diseases. In this review, we discuss senescence-related mitochondrial changes and consequent mitochondrial metabolic alterations. We assess the significance of mitochondrial metabolic reprogramming for senescence regulation and propose the appropriate control of mitochondrial metabolism to ameliorate senescence. Learning how to regulate mitochondrial metabolism will provide knowledge for the control of aging and age-related pathologies. Further research focusing on mitochondrial metabolic reprogramming will be an important guide for the development of anti-aging therapies, and will provide novel strategies for anti-aging interventions.

MiR-125b enhances autophagic flux to improve septic cardiomyopathy via targeting STAT3/HMGB1

We explore the role of miR-125b in septic cardiomyopathy, focusing on miR-125b/STAT3/HMGB1 axis. CLP mouse model and LPS-stimulated primary rat cardiomyocytes (CMs) and H9C2 cell were used as in vivo and in vitro models of septic cardiomyopathy, respectively. qRT-PCR and western blot were performed to measure expression levels of miR-125b, STAT3, HMGB1, and autophagy-related proteins. MTT assay was employed to examine LPS toxicity. Dual luciferase activity assay and CHIP were performed to validate interactions of miR-125b/STAT3 and STAT3/HMGB1 promoter. Immunostaining was used to assess the level of autophagic flux. ROS level was measured by fluorescence assay. Heart functions were examined via intracoronary Doppler ultrasound. miR-125b was diminished while STAT3 and HMGB1 were elevated in the heart tissue following CLP surgery and in LPS-treated H9C2 cells. LPS treatment up-regulated ROS generation and suppressed autophagic flux. Overexpression of miR-125b mimics or knockdown of STAT3 or HMGB1 alleviated LPS-induced hindrance of autophagic flux and ROS production. miR-125b directly targeted STAT3 mRNA and STAT3 bound with HMGB1 promoter. Overexpression of miR-125b mitigated myocardial dysfunction induced by CLP in vivo. Hyperactivation of STAT3/HMGB1 caused by reduced miR-125b contributes to ROS generation and the hindrance of autophagic flux during septic cardiomyopathy, leading to myocardial dysfunction.

Prohibitin-1 Is a Dynamically Regulated Blood Protein With Cardioprotective Effects in Sepsis

Background In sepsis, circulating cytokines and lipopolysaccharide elicit mitochondrial dysfunction and cardiomyopathy, a major cause of morbidity and mortality with this condition. Emerging research places the PHB1 (lipid raft protein prohibitin-1) at the nexus of inflammation, metabolism, and oxidative stress. PHB1 has also been reported in circulation, though its function in this compartment is completely unknown. Methods and Results Using a wide-ranging approach across multiple in vitro and in vivo models, we interrogated the functional role of intracellular and circulating PHB1 in the heart during sepsis, and elucidated some of the mechanisms involved. Upon endotoxin challenge or sepsis induction in rodent models, PHB1 translocates from mitochondria to nucleus in cardiomyocytes and is secreted into the circulation from the liver in a manner dependent on nuclear factor (erythroid-derived 2)-like 2, a key transcriptional regulator of the antioxidant response. Overexpression or treatment with recombinant human PHB1 enhances the antioxidant/anti-inflammatory response and protects HL-1 cardiomyocytes from mitochondrial dysfunction and toxicity from cytokine stress. Importantly, administration of recombinant human PHB1 blunted inflammation and restored cardiac contractility and ATP production in mice following lipopolysaccharide challenge. This cardioprotective, anti-inflammatory effect of recombinant human PHB1 was determined to be independent of nuclear factor (erythroid-derived 2)-like 2, but partially dependent on PI3K/AKT  signaling in the heart. Conclusions These findings reveal a previously unknown cardioprotective effect of PHB1 during sepsis, and illustrate a pro-survival, protective role for PHB1 in the circulation. Exploitation of circulating PHB1 as a biomarker and/or therapeutic could have widespread benefit in the clinical management of sepsis and other severe inflammatory disorders.

Pathogenetic mechanisms of septic cardiomyopathy

Sepsis is a serious complication after infection, whose further development may lead to multiple organ dysfunction syndrome and so on. It is an important cause of death in critically ill patients who suffered an infection. Sepsis cardiomyopathy is a common complication that exacerbates the prognosis of patients. At present, though the pathogenesis of sepsis cardiomyopathy is not completely clear, in-depth study of the pathogenesis of sepsis cardiomyopathy and the discovery of its potential therapeutic targets may decrease the mortality of sepsis patients and bring clinical benefits. This article reviews mitochondrial dysfunction, mitophagy, oxidation stress, and other mechanisms in sepsis cardiomyopathy.

Overexpression of Peroxisome Proliferator-Activated Receptor γ Coactivator 1-α Protects Cardiomyocytes from Lipopolysaccharide-Induced Mitochondrial Damage and Apoptosis

Mitochondrial damage is considered one of the main pathogenetic mechanisms in septic cardiomyopathy. Peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) is critical for maintaining energy homeostasis in different organs and in various physiological and pathological states. It is also a key regulator gene in mitochondrial metabolism. In this study, we investigated whether regulation of the PGC-1α gene had protective effects on septic cardiomyopathy. We developed a rat model of septic cardiomyopathy. H9c2 myocardiocytes were treated with lipopolysaccharide (LPS) and PGC-1α expression measured. PGC-1α-overexpressing lentivirus was used to transfect H9c2 cells. ZLN005 was used to activate PGC-1α. The effect of the inhibition of PGC-1α expression on myocardial cell injury and its underlying mechanisms were also explored. Cell viability was measured by CCK-8 assay. Mitochondrial damage was determined by measuring cellular ATP, reactive oxygen species, and the mitochondrial membrane potential. An apoptosis analysis kit was used to measure cellular apoptosis. Mitochondrial DNA was extracted and real-time PCR performed. LC3B, mitochondrial transcription factor A (TFA), P62, Bcl2, and Bax were determined by immunofluorescence. LC3B, TFA, P62, Parkin, PTEN-induced putative kinase 1, and PGC-1α proteins were determined by Western blotting. We found mitochondrial damage and apoptotic cells in the myocardial tissue of rats with septic cardiomyopathy and in LPS-treated cardiomyocytes. PGC-1α expression was decreased in the late phase of septic cardiomyopathy and in LPS-treated cardiomyocytes. PGC-1α activation by ZLN005 and PGC-1α overexpression reduced apoptosis in myocardiocytes after LPS incubation. PGC-1α gene overexpression alleviated LPS-induced cardiomyocyte mitochondrial damage by activating mitochondrial biogenesis and autophagy functions. Our study indicated that mitochondrial damage and apoptosis occurred in septic cardiomyopathy and LPS-treated cardiomyocytes. The low expression level of PGC-1α protein may have contributed to this damage. By activating the expression of PGC-1α, apoptosis was reduced in cardiomyocytes. The underlying mechanism may be that PGC-1α can activate mitochondrial biogenesis and autophagy functions, reducing mitochondrial damage and thereby reducing apoptosis.

Emodin alleviates LPS-induced myocardial injury through inhibition of NLRP3 inflammasome activation

Myocardial injury and cardiovascular dysfunction are serious consequences of sepsis and contribute to high mortality. Currently, the pathogenesis of myocardial injury in sepsis is still unclear, and therapeutic approaches are limited. In this study, we investigated the protective effect of emodin on septic myocardial injury and the underlying mechanism. Lipopolysaccharide (LPS)-induced C57BL/6 mice and cardiomyocytes were used as models of sepsis in vivo and in vitro, respectively. The results showed that emodin alleviated cardiac dysfunction, myocardial injury and improved survival rate in LPS-induced septic mice. Emodin attenuated the levels of inflammatory cytokines and cardiac inflammation induced by LPS. Emodin reduced NOD-like receptor protein 3 (NLRP3) and Gasdermin D (GSDMD) expression in the heart tissue of LPS-induced septic mice. In vitro, emodin alleviated LPS-induced cell injury and inflammation in cardiomyocytes by inhibiting NLRP3 inflammasome activation. In addition, an NLRP3 inhibitor was used to further confirm the function of the NLRP3 inflammasome in LPS-induced myocardial injury. Taken together, our findings suggest that emodin improves LPS-induced myocardial injury and cardiac dysfunction by alleviating the inflammatory response and cardiomyocyte pyroptosis by inhibiting NLRP3 inflammasome activation, which provides a feasible strategy for preventing and treating myocardial injury in sepsis.

Silencing Cardiac Troponin I-Interacting Kinase Reduces Lipopolysaccharide-Induced Sepsis-Induced Myocardial Dysfunction in Rat by Regulating Apoptosis-Related Proteins

The aim of this study was to investigate the effect of cardiac troponin I-interacting kinase (TNNI3K) on sepsis-induced myocardial dysfunction (SIMD) and further explore the underlying molecular mechanisms. In this study, a lipopolysaccharide- (LPS-) induced myocardial injury model was used. qRT-PCR was performed to detect the mRNA expression of TNNI3K. Western blot was conducted to quantitatively detect the expression of TNNI3K and apoptosis-related proteins (Bcl-2, Bax, and caspase-3). ELISA was performed to detect the content of lactate dehydrogenase (LDH) and creatine kinase (CK). TUNEL assay was used to detect the apoptosis of H9C2 cells. In LPS-induced H9C2 cells, TNNI3K was up regulated. Besides, the CK activity, the content of LDH, and the apoptosis of H9C2 cells were significantly increased after treatment with LPS. Silencing TNNI3K decreased the LDH release activity and CK activity and inhibited apoptosis of H9C2 cell. Further research illustrated that si-TNNI3K promoted the protein expression of Bcl-2 and decreased the protein expression of Bax and cleaved caspase-3. The study concluded that TNNI3K was upregulated in LPS-induced H9C2 cells. Importantly, functional research findings indicated that silencing TNNI3K alleviated LPS-induced H9C2 cell injury by regulating apoptosis-related proteins.

Inhibiting miR-22 Alleviates Cardiac Dysfunction by Regulating Sirt1 in Septic Cardiomyopathy

High morbidity and mortality are the most typical characteristics of septic cardiomyopathy. We aimed to reveal the role of miR-22 in septic cardiomyopathy and to explore the underlying mechanisms. miR-22 cardiac-specific knockout (miR-22^cKO) mice and miR-22 cardiac-specific transgenic (miR-22^cOE) mice were subjected to a cecal ligation and puncture (CLP) operation, while a sham operation was used in the control group. The echocardiogram results suggested that miR-22^cKO CLP mice cardiac dysfunction was alleviated. The serum LDH and CK-MB were reduced in the miR-22^cKO CLP mice. As expected, there was reduced apoptosis, increased autophagy and alleviated mitochondrial dysfunction in the miR-22^cKO CLP mice, while it had contrary role in the miR-22^cOE group. Inhibiting miR-22 promoted autophagy by increasing the LC3II/GAPDH ratio and decreasing the p62 level. Additionally, culturing primary cardiomyocytes with lipopolysaccharide (LPS) simulated sepsis-induced cardiomyopathy in vitro. Inhibiting miR-22 promoted autophagic flux confirmed by an increased LC3II/GAPDH ratio and reduced p62 protein level under bafilomycin A1 conditions. Knocking out miR-22 may exert a cardioprotective effect on sepsis by increasing autophagy and decreasing apoptosis via sirt1. Our results revealed that targeting miR-22 may become a new strategy for septic cardiomyopathy treatment.

Septic Cardiomyopathy: From Basics to Management Choices

Septic cardiomyopathy (SCM) is increasingly recognized as a potential complication of septic shock; it is understood to be a reversible left ventricular systolic dysfunction. The presence of SCM in septic shock, in previous studies, infer a poorer prognosis as it significantly increases the mortality rate of patients to 70%-90% and its incidence varies from 18% to 40% of septic shock patients. The pathogenesis is unclear, but believed to be a combination of bacterial toxins, cytokines, nitric oxide, and cardiac mitochondrial dysfunction, that depresses intrinsic cardiac contractility. The presence of SCM can be diagnosed in patients using a bedside transthoracic echocardiogram which typically shows left ventricular ejection fraction <45% and right ventricular dilatation. For management, levosimendan provides a good hemodynamic response without increasing cardiac oxygen demand when compared to dobutamine, while more invasive techniques such as extracorporeal membrane oxygenation, and intra-aortic balloon pulsation are being explored as well as potential rescue strategies for patients with severe SCM.

Exploring plasma metabolomic changes in sepsis: a clinical matching study based on gas chromatography-mass spectrometry

Background

Sepsis is a deleterious systemic inflammatory response to infection, and despite advances in treatment, the mortality rate remains high. We hypothesized that plasma metabolism could clarify sepsis in patients complicated by organ dysfunction.

Methods

Plasma samples from 31 patients with sepsis and 23 healthy individuals of comparable age, gender, and body mass index (BMI) were collected. Plasma metabolites were detected through gas chromatography–mass spectrometry (GC–MS), and relevant metabolic pathways were predicted using the Kyoto Encyclopedia of Genes and Genomics (KEGG) pathway database. Student’s t-test was employed for statistical analysis. In addition, to explore sepsis organ dysfunction, plasma samples of sepsis patients were further analyzed by metabolomics subgroup analysis according to organ dysfunction.

Results

A total of 222 metabolites were detected, which included 124 metabolites with statistical significance between the sepsis and control groups. Among these, we found 26 were fatty acids, including 3 branched fatty acids, 10 were saturated fatty acids, and 13 were unsaturated fatty acids that were found in sepsis plasma samples but not in the controls. In addition, 158 metabolic pathways were predicted, 74 of which were significant. Further subgroup analysis identified seven metabolites in acute kidney injury (AKI), three metabolites in acute respiratory distress syndrome (ARDS), seven metabolites in sepsis-induced myocardial dysfunction (SIMD), and four metabolites in acute hepatic ischemia (AHI) that were significantly different. The results showed that the sepsis samples exhibited extensive changes in amino acids, fatty acids, and tricarboxylic acid (TCA)–cycle products. In addition, three metabolic pathways—namely, energy metabolism, amino acid metabolism, and lipid metabolism—were downregulated in sepsis patients.

Conclusions

The downregulated energy, amino acid, and lipid metabolism found in our study may serve as a novel clinical marker for the dysregulated internal environment, particularly involving energy metabolism, which results in sepsis.

Shenfu injection prevents sepsis-induced myocardial injury by inhibiting mitochondrial apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Shenfu injection (SFI) is a well-known Chinese herbal medicine widely used in the treatment of septic shock in China.

AIMS

The aims of this study are to investigate the protective effects of SFI on sepsis-induced myocardial injury in mice and to identify the underlying mechanism of action.

MATERIALS AND METHODS

Seventy-two male C57/B6J mice (5-6 weeks old) were randomly divided into five groups: control (NC), sham sepsis (sham), sepsis (Lipopolysaccharide- LPS), sepsis treated with a low dose SFI, and sepsis treated with a high dose SFI. Sepsis was induced in mice by intraperitoneal injection of LPS. Myocardial tissue samples were collected from different groups at 6 h, 12 h, and 24 h post-LPS injection. Myocardial injury was examined using hematoxylin-eosin (H&E) and TUNEL staining. Western-blot analysis was performed to determine the protein expression of B-cell lymphoma 2 (Bcl-2), BH3 interacting-domain death agonist (Bid), truncated-Bid (t-Bid) and caspase-9 in all the groups. Moreover, the structural changes in the mitochondria of cardiomyocytes were also observed by transmission electron microscopy.

RESULTS

H&E staining revealed structural damage, local necrosis, interstitial edema, inflammatory cell infiltration and vacuolar changes in the myocardial tissue in the sepsis (LPS) group; almost intact myocardial tissue was observed in the high dose SFI group with improvements in interstitial edema and inflammatory cell infiltration. We observed that LPS-induced cardiomyocyte apoptosis was significantly improved with high dose SFI as compared with sepsis (LPS) group (P ˂ 0.05). LPS was found to decrease the protein expression of Bcl-2 and increase the level of Bid, t-Bid and caspase-9. Treatment with SFI significantly increased the Bcl-2 protein expression (P ˂ 0.05) and decreased the protein expression of Bid, t-Bid and caspase-9 as compared with LPS group (P ˂ 0.05). Markedly swollen myocardial mitochondria with partial vacuolation were observed in LPS treated mice while SFI treatment was found to significantly improve the LPS-induced morphological damage of the mitochondria.

CONCLUSION

In conclusion, we demonstrate that SFI protects against sepsis-induced myocardial injury in mice through the suppression of myocardial apoptosis. It upregulates the protein expression of Bcl-2 and downregulates the protein expression of Bid, t-Bid and caspase-9, and alleviates sepsis-induced mitochondrial damage.

Exploring the pathophysiology of post-sepsis syndrome to identify therapeutic opportunities

Sepsis is a major health problem worldwide. As the number of sepsis cases increases, so does the number of sepsis survivors who suffer from “post-sepsis syndrome” after hospital discharge. This syndrome involves deficits in multiple systems, including the immune, cognitive, psychiatric, cardiovascular, and renal systems. Combined, these detrimental consequences lead to rehospitalizations, poorer quality of life, and increased mortality. Understanding the pathophysiology of these issues is crucial to develop new therapeutic opportunities to improve survival rate and quality of life of sepsis survivors. Such novel strategies include modulating the immune system and addressing mitochondrial dysfunction. A sepsis follow-up clinic may be useful to identify long-term health issues associated with post-sepsis syndrome and evaluate existing and novel strategies to improve the lives of sepsis survivors.

Inhibition of circulating dipeptidyl-peptidase 3 restores cardiac function in a sepsis-induced model in rats: A proof of concept study

Sepsis is a global economic and health burden. Dipeptidyl peptidase 3 (DPP3) is elevated in the plasma of septic patients. The highest levels of circulating DPP3 (cDPP3) are found in non-survivor septic shock patients. The aim of this study was to evaluate the benefits of inhibiting cDPP3 by a specific antibody, Procizumab (PCZ), on cardiac function in an experimental model of sepsis, the caecal ligature and puncture (CLP) model. Rats were monitored by invasive blood pressure and echocardiography. Results are presented as mean ± SD, with p <0.05 considered significant. PCZ rapidly restored left ventricular shortening fraction (from 39 ± 4% to 51 ± 2% before and 30 min after PCZ administration (p = 0.004)). Cardiac output and stroke volume were higher in the CLP + PCZ group when compared to the CLP + PBS group (152 ± 33 mL/min vs 97 ± 25 mL/min (p = 0.0079), and 0.5 ± 0.1 mL vs 0.3 ± 1.0 mL (p = 0.009), respectively) with a markedly reduced plasma DPP3 activity (138 ± 70 U/L in CLP + PCZ group versus 735 ± 255 U/L (p = 0.048) in the CLP + PBS group). Of note, PCZ rapidly reduced oxidative stress in the heart of the CLP + PCZ group when compared to those of the CLP + PBS group (13.3 ± 8.2 vs 6.2 ± 2.5 UI, p = 0.005, 120 min after administration, respectively). Our study demonstrates that inhibition of cDPP3 by PCZ restored altered cardiac function during sepsis in rats.

Heart Dysfunction in Sepsis

Cardiac involvement during sepsis frequently occurs. A series of molecules induces a set of changes at the cellular level that result in the malfunction of the myocardium. The understanding of these molecular alterations has simultaneously promoted the implementation of diagnostic strategies that are much more precise and allowed the advance of the therapeutics. The heart is a vital organ for survival. Its well-being ensures the adequate supply of essential elements for organs and tissues.

Neuregulin‑1: An underlying protective force of cardiac dysfunction in sepsis (Review)

Neuregulin-1 (NRG-1) is a type of epidermal growth factor‑like protein primarily distributed in the nervous and cardiovascular systems. When sepsis occurs, the incidence of cardiac dysfunction in myocardial injury is high and the mechanism is complicated. It directly causes myocardial cell damage, whilst also causing damage to the structure and function of myocardial cells, weakening of endothelial function and coronary microcirculation, autonomic dysfunction, and activation of myocardial inhibitory factors. Studies investigating NRG‑1 have been performed using a variety of methods, including in vitro models, and animal and human clinical trials; however, the results are not consistent. NRG‑1/ErbBs signaling is involved in a variety of cardiac processes, from the development of the myocardium and cardiac conduction systems to the promotion of angiogenesis in cardiomyocytes, and in cardio‑protective effects during injury. NRG‑1 may exert a multifaceted cardiovascular protective effect by activating NRG‑1/ErbBs signaling and regulating multiple downstream signaling pathways, thereby improving myocardial cell dysfunction in sepsis, and protecting cardiomyocytes and endothelial cells. It may alleviate myocardial microvascular endothelial injury in sepsis; its anti‑inflammatory effects inhibit the production of myocardial inhibitory factors in sepsis, improve myocardial ischemia, decrease oxidative stress, regulate the disruption to the homeostasis of the autonomic nervous system, improve diastolic function, and offer protective effects at multiple target sites. As the mechanism of action of NRG‑1 intersects with the pathways involved in the pathogenesis of sepsis, it may be applicable as a treatment strategy to numerous pathological processes in sepsis.

STAPLAg: a convenient early warning score for use in infected patients in the intensive care unit

Sepsis is a life-threatening disease in the intensive care unit (ICU). The current diagnostic criteria for sequential organ failure assessment (SOFA) scores do not reflect the current understanding of sepsis. We developed a novel and convenient score to aid early prognosis.Retrospective multivariable regression analysis of 185 infected emergency ICU (EICU) patients was conducted to identify independent variables associated with death, to develop the new "STAPLAg" score; STAPLAg was then validated in an internal cohort (n = 106) and an external cohort (n = 78) and its predictive efficacy was compared with that of the initial SOFA score.Age, and initial serum albumin, sodium, PLR, troponin, and lactate tests in the emergency department were independent predictors of death in infected EICU patients, and were used to establish the STAPLAg score (area under the curve [AUC] 0.865). The initial SOFA score on admission was predictive of death (AUC 0.782). Applying the above categories to the derivation cohort yielded mortality risks of 7.7% for grade I, 56.3% for grade II, and 75.0% for grade III. Internal (AUC 0.884) and external (AUC 0.918) cohort validation indicated that the score had good predictive power.The STAPLAg score can be determined early in infected EICU patients, and exhibited better prognostic capacity than the initial SOFA score on admission in both internal and external cohorts. STAPLAg constitutes a new resource for use in the clinical diagnosis of sepsis and can also predict mortality in infected EICU patients. REGISTRATION NUMBER:: ChinCTR-PNC-16010288.

Shenfu injection attenuates lipopolysaccharide-induced myocardial inflammation and apoptosis in rats

Shenfu injection (SFI), a Chinese medicinal product, shows potent efficacy in treating sepsis. The aim of the present study was to clarify the protective effects of SFI against lipopolysaccharide (LPS)-induced myocardial inflammation and apoptosis. Experiments were carried out in Sprague-Dawley (SD) rats treated with LPS or LPS + SFI, and in H9C2 cardiomyocytes. The sepsis-associated myocardial inflammation and apoptosis was induced by the intraperitoneal injection of LPS (20 mg·kg^-1). SFI attenuated the increased expression of tumor necrosis factor (TNF)-α and interleukin (IL)-1β induced by LPS both in serum and heart. In LPS group, cell viability was reduced, and reversed after SFI administration. LPS treatment increased the expression levels of cleaved-caspase 3 and Bax, and those of Bcl2 and Bcl2/Bax. These two trends were reversed by SFI administration. The expression levels of phosphorylated mitogen-activated protein kinase kinase (p-MEK) and phosphorylated extracellular regulated protein kinases (p-ERK) were increased by LPS, and reversed by SFI. MEK inhibitor U0126 attenuated the apoptosis induced by LPS. These results indicate that SFI could treat LPS-induced cardiac dysfunction. In conclusion, SFI attenuates the inflammation and apoptosis induced by LPS via downregulating the MEK and ERK signaling pathways.

Role of eotaxin-1/CCL11 in sepsis-induced myocardial injury in elderly patients

Myocardial injury is a serious complication of sepsis. The present study aimed to identify potential biomarkers of sepsis-induced myocardial injury. Differentially expressed genes (DEGs) in patients and mice with sepsis-induced myocardial injury were identified via bioinformatic analysis. The identified DEG was tested in elderly patients with sepsis-induced myocardial injury. We identified 19 co-expressed DEGs. The most significant DEG was eotaxin-1/CCL11. We enrolled 25 controls without infections and 28 patients with sepsis-induced myocardial injury. Six of patients died within 30 days. Circulating eotaxin-1/CCL11 levels were significantly higher in patients with sepsis-induced myocardial injury than controls and were higher in non-survivors than survivors (both P < 0.01). Eotaxin-1/CCL11 was positively correlated with troponin I (r=0.48, P=0.01), B-type natriuretic peptide (BNP, r=0.44, P=0.02), and white blood cell (WBC) count (r=0.41, P=0.03). For the prediction of 30-day mortality, eotaxin-1/CCL11 had the greatest discriminatory ability (AUC 0.97) compared with troponin I (AUC 0.89), BNP (AUC 0.80), and WBC count (AUC 0.86). Taken together, eotaxin-1/CCL11 was upregulated in sepsis-injured myocardium and circulating eotaxin-1/CCL11 was a biomarker for predicting severity and mortality of elderly patients with sepsis-induced myocardial injury. These results suggest that eotaxin-1/CCL11 may become a useful biomarkers and potential therapeutic target for sepsis-induced myocardial injury.

Current Status of Septic Cardiomyopathy: Basic Science and Clinical Progress

Septic cardiomyopathy (SCM) is a complication that is sepsis-associated cardiovascular failure. In the last few decades, there is progress in diagnosis and treatment despite the lack of consistent diagnostic criteria. According to current studies, several hypotheses about pathogenic mechanisms have been revealed to elucidate the pathophysiological characteristics of SCM. The objective of this manuscript is to review literature from the past 5 years to provide an overview of current knowledge on pathogenesis, diagnosis and treatment in SCM.