β3-Adrenergic receptor blockade reduces mortality in endotoxin-induced heart failure by suppressing induced nitric oxide synthase and saving cardiac metabolism

ENDOGENOUS β 3 -ADRENERGIC RECEPTOR ACTIVATION ALLEVIATES SEPSIS-INDUCED CARDIOMYOCYTE APOPTOSIS VIA PI3K/AKT SIGNALING PATHWAY

ABSTRACT

β 3 -adrenergic receptor (β 3 -AR) has been proposed as a new therapy for several myocardial diseases. However, the effect of β 3 -AR activation on sepsis-induced myocardial apoptosis is unclear. Here, we investigated the effect of β 3 -AR activation on the cardiomyocyte apoptosis and cardiac dysfunction in cecal ligation and puncture (CLP)-operated rats and lipopolysaccharide (LPS)-treated cardiomyocytes. We found that β 3 -AR existed both in adult rat ventricular myocytes (ARVMs) and H9c2 cells. The expression of β 3 -AR was upregulated in LPS-treated ARVMs and the heart of CLP rats. Pretreatment with β 3 -AR agonist, BRL37344, inhibited LPS-induced cardiomyocyte apoptosis and caspase-3, -8, and -9 activation in ARVMs. BRL37344 also reduced apoptosis and increased the protein levels of PI3K, p-Akt Ser473 and p-eNOS Ser1177 in LPS-treated H9c2 cells. Inhibition of PI3K using LY294002 abolished the inhibitory effect of BRL37344 on LPS-induced caspase-3, -8, and -9 activation in H9c2 cells. Furthermore, administration of β 3 -AR antagonist, SR59230A (5 mg/kg), significantly decreased the maximum rate of left ventricular pressure rise (+dP/dt) in CLP-induced septic rats. SR59230A not only increased myocardial apoptosis, reduced p-Akt Ser473 and Bcl-2 contents, but also increased mitochondrial Bax, cytoplasm cytochrome c, cleaved caspase-9, and cleaved caspase-3 levels of the myocardium in septic rats. These results suggest that endogenous β 3 -AR activation alleviates sepsis-induced cardiomyocyte apoptosis via PI3K/Akt signaling pathway and maintains intrinsic myocardial systolic function in sepsis.

Current Perspectives of Mitochondria in Sepsis-Induced Cardiomyopathy

Sepsis-induced cardiomyopathy (SICM) is one of the leading indicators for poor prognosis associated with sepsis. Despite its reversibility, prognosis varies widely among patients. Mitochondria play a key role in cellular energy production by generating adenosine triphosphate (ATP), which is vital for myocardial energy metabolism. Over recent years, mounting evidence suggests that severe sepsis not only triggers mitochondrial structural abnormalities such as apoptosis, incomplete autophagy, and mitophagy in cardiomyocytes but also compromises their function, leading to ATP depletion. This metabolic disruption is recognized as a significant contributor to SICM, yet effective treatment options remain elusive. Sepsis cannot be effectively treated with inotropic drugs in failing myocardium due to excessive inflammatory factors that blunt β-adrenergic receptors. This review will share the recent knowledge on myocardial cell death in sepsis and its molecular mechanisms, focusing on the role of mitochondria as an important metabolic regulator of SICM, and discuss the potential for developing therapies for sepsis-induced myocardial injury.

Ginsenoside Rg3, enriched in red ginseng extract, improves lipopolysaccharides-induced suppression of brown and beige adipose thermogenesis with mitochondrial activation

Brown adipose tissue (BAT) which is a critical regulator of energy homeostasis, and its activity is inhibited by obesity and low-grade chronic inflammation. Ginsenoside Rg3, the primary constituent of Korean red ginseng (steamed Panax ginseng CA Meyer), has shown therapeutic potential in combating inflammatory and metabolic diseases. However, it remains unclear whether Rg3 can protect against the suppression of browning or activation of BAT induced by inflammation. In this study, we conducted a screening of ginsenoside composition in red ginseng extract (RGE) and explored the anti-adipogenic effects of both RGE and Rg3. We observed that RGE (exist 0.25 mg/mL of Rg3) exhibited significant lipid-lowering effects in adipocytes during adipogenesis. Moreover, treatment with Rg3 (60 μM) led to the inhibition of triglyceride accumulation, subsequently promoting enhanced fatty acid oxidation, as evidenced by the conversion of radiolabeled 3H-fatty acids into 3H-H2O with mitochondrial activation. Rg3 alleviated the attenuation of browning in lipopolysaccharide (LPS)-treated beige adipocytes and primary brown adipocytes by recovered by uncoupling protein 1 (UCP1) and the oxygen consumption rate compared to the LPS-treated group. These protective effects of Rg3 on inflammation-induced inhibition of beige and BAT-derived thermogenesis were confirmed in vivo by treating with CL316,243 (a beta-adrenergic receptor agonist) and LPS to induce browning and inflammation, respectively. Consistent with the in vitro data, treatment with Rg3 (2.5 mg/kg, 8 weeks) effectively reversed the LPS-induced inhibition of brown adipocyte features in C57BL/6 mice. Our findings confirm that Rg3-rich foods are potential browning agents that counteract chronic inflammation and metabolic complications.

Dexmedetomidine post-treatment exacerbates metabolic disturbances in septic cardiomyopathy via α2A-adrenoceptor

Cardiomyopathy is a common complication and significantly increases the risk of death in septic patients. Our previous study demonstrated that post-treatment with dexmedetomidine (DEX) aggravates septic cardiomyopathy. However, the mechanisms for the side effect of DEX post-treatment on septic cardiomyopathy are not well-defined. Here we employed a cecal ligation and puncture (CLP) model and α2A-adrenoceptor deficient (Adra2a-/-) mice to observe the effects of DEX post-treatment on myocardial metabolic disturbances in sepsis. CLP mice displayed significant cardiac dysfunction, altered mitochondrial dynamics, reduced cardiac lipid and glucose uptake, impaired fatty acid and glucose oxidation, enhanced glycolysis and decreased ATP production in the myocardium, almost all of which were dramatically enhanced by DEX post-treatment in septic mice. In Adra2a-/- mice, DEX post-treatment did not affect cardiac dysfunction and metabolic disruptions in CLP-induced sepsis. Additionally, Adra2a-/- mice exhibited impaired cardiac function, damaged myocardial mitochondrial structures, and disturbed fatty acid metabolism and glucose oxidation. In sum, DEX post-treatment exacerbates metabolic disturbances in septic cardiomyopathy in a α2A-adrenoceptor dependent manner.

Ameliorating effects of berberine on sepsis-associated lung inflammation induced by lipopolysaccharide: molecular mechanisms and preclinical evidence

As a life-threatening disorder, sepsis-associated lung injury is a dysregulated inflammatory response to microbial infection, characterized by the infiltration of inflammatory cells into lung tissues and excessive production of pro-inflammatory mediators. Therefore, immunomodulatory/anti-inflammatory agents are a potential treatment for sepsis-associated lung injury. Berberine, one of the well-studied medicinal plant-derived compounds, has shown promising anti-inflammatory potential in inflammatory conditions, through modulating excessive immune responses induced by various immune cells. A systematic literature search in electronic databases indicated several publications that studied the effect of berberine on lipopolysaccharide (LPS)-induced sepsis in preclinical investigations. The current review article aims to provide evidence on the effects of berberine against LPS-induced acute lung injury (ALI), together with underlying molecular mechanisms. The findings reveal that berberine through inhibiting the excessive production of multiple pro-inflammatory cytokines, suppressing the infiltration of immune cells into lung tissues, as well as preventing pulmonary edema and coagulation, can relieve pulmonary histopathological changes from LPS-mediated inflammation, thereby attenuating sepsis-associated lung injury and lethality in the experimental models. In conclusion, berberine shows great potential as a preventing and therapeutic agent for sepsis-associated lung injury, however, further proof-of-concept studies and clinical investigations are warranted for translating these preclinical findings into clinical practices.

Berberine attenuates sepsis‑induced cardiac dysfunction by upregulating the Akt/eNOS pathway in mice

The present study aimed to investigate the cardioprotective role of berberine in sepsis-induced cardiac dysfunction and consider the underlying mechanisms. C57BL/6J mice were randomized into four groups, namely, Control, lipopolysaccharide (LPS), LPS + berberine and LPS + N^ω-nitro-L-arginine methyl ester (L-NAME) + berberine. A single dose (10 mg/kg body weight) of LPS was intraperitoneally administered to mice to induce cardiac dysfunction, whereas the Control group was administered with an equivalent volume of saline. In the LPS + berberine and LPS + L-NAME + berberine group, berberine (10 mg/kg body weight) dissolved in hot water was intraperitoneally administered 30 min after the LPS treatment. In the LPS + L-NAME + berberine group, L-NAME (100 mg/kg body weight) dissolved in saline was intraperitoneally administered 30 min before the LPS treatment. Then, ~6 h after the LPS treatment, a significant decrease was observed in the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS). Meanwhile, the plasma myocardial injury markers, inflammatory factors and oxidative stress levels were significantly increased in the LPS group compared with the Control group. The administration of berberine improved the ventricular function and decreased the plasma myocardial injury markers, inflammatory factors and oxidative stress levels. In addition, it increased the heart total nitric oxide synthase (NOS) activity and upregulated the protein expressions of p-Akt and phosphorylated endothelial (e)NOS, which indicated that the Akt/eNOS pathway was activated by berberine. However, the cardioprotective effects of berberine were counteracted by L-NAME, an NOS inhibitor, which inhibited the eNOS activity. In conclusion, berberine attenuated sepsis-induced cardiac dysfunction by upregulating the Akt/eNOS pathway in mice.

Cardiac Metabolism in Sepsis

The mechanism of sepsis-induced cardiac dysfunction is believed to be different from that of myocardial ischemia. In sepsis, chemical mediators, such as endotoxins, cytokines, and nitric oxide, cause metabolic abnormalities, mitochondrial dysfunction, and downregulation of β-adrenergic receptors. These factors inhibit the production of ATP, essential for myocardial energy metabolism, resulting in cardiac dysfunction. This review focuses on the metabolic changes in sepsis, particularly in the heart. In addition to managing inflammation, interventions focusing on metabolism may be a new therapeutic strategy for cardiac dysfunction due to sepsis.

Depletion of β3-adrenergic receptor relieves pressure overload-induced cardiac hypertrophy and heart failure via enhancing innate immune response

Cardiac pressure overload is a crucial risk factor for cardiac hypertrophy and heart failure. Our previous study showed that depletion of the β3-adrenergic receptor (ADRB3) induced left ventricular diastolic dysfunction via potential regulation of energy metabolism and cardiac contraction. However, the effects of ADRB3 on pressure overload-induced heart failure remain unclear. In the present study, systemic ADRB3-knockout mice suffering from transverse aortic constriction (TAC) surgery were used to identify the effects of ADRB3 on pressure overload-induced heart failure. Compared to wild-type mice, ADRB3 depletion significantly improved the left ventricular ejection fraction, reduced left ventricular posterior wall thickness and interventricular septum thickness, and decreased the area of cardiomyocytes after TAC. RNA sequencing and bioinformatics analysis showed that ADRB3 depletion up-regulated 275 mRNAs and down-regulated 105 mRNAs in mice suffering TAC surgery. GO analysis, GO-tree analysis, and GSEA showed that ADRB3 depletion mainly enhanced the innate immune response of hearts in cardiac pressure overload mice. In addition, pathway analysis and Pathway-Act analysis presented that innate immune response-related pathways, including RIG-I-like receptor signaling pathway, antigen processing and presentation, Toll-like receptor signaling pathway, and cell adhesion molecules, were significantly enriched in ADRB3-KO-TAC mice. Ten hub genes were identified using protein-protein interaction network, MCODE, and cytoHubba analysis. Furthermore, the depletion and activation of ADRB3 validated the effects of ADRB3 on the innate immune response of hearts after TAC. In conclusion, ADRB3 depletion relieves pressure overload-induced cardiac hypertrophy and heart failure, and these effects could be explained by the enhancement of innate immune response.

Comprehensive Mechanism, Novel Markers and Multidisciplinary Treatment of Severe Acute Pancreatitis-Associated Cardiac Injury - A Narrative Review

Acute pancreatitis (AP) is one of the common acute abdominal inflammatory diseases in clinic with acute onset and rapid progress. About 20% of the patients will eventually develop into severe acute pancreatitis (SAP) characterized by a large number of inflammatory cells infiltration, gland flocculus flaky necrosis and hemorrhage, finally inducing systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). Pancreatic enzyme activation, intestinal endotoxemia (IETM), cytokine activation, microcirculation disturbance, autonomic nerve dysfunction and autophagy dysregulation all play an essential role in the occurrence and progression of SAP. Organ dysfunction is the main cause of early death in SAP. Acute kidney injury (AKI) and acute lung injury (ALI) are common, while cardiac injury (CI) is not, but the case fatality risk is high. Many basic studies have observed obvious ultrastructure change of heart in SAP, including myocardial edema, cardiac hypertrophy, myocardial interstitial collagen deposition. Moreover, in clinical practice, patients with SAP often presented various abnormal electrocardiogram (ECG) and cardiac function. Cases complicated with acute myocardial infarction and pericardial tamponade have also been reported and even result in stress cardiomyopathy. Due to the molecular mechanisms underlying SAP-associated cardiac injury (SACI) remain poorly understood, and there is no complete, unified treatment and sovereign remedy at present, this article reviews reports referring to the pathogenesis, potential markers and treatment methods of SACI in recent years, in order to improve the understanding of cardiac injury in severe pancreatitis.

Targeting Adrenergic Receptors in Metabolic Therapies for Heart Failure

The heart has a reduced capacity to generate sufficient energy when failing, resulting in an energy-starved condition with diminished functions. Studies have identified numerous changes in metabolic pathways in the failing heart that result in reduced oxidation of both glucose and fatty acid substrates, defects in mitochondrial functions and oxidative phosphorylation, and inefficient substrate utilization for the ATP that is produced. Recent early-phase clinical studies indicate that inhibitors of fatty acid oxidation and antioxidants that target the mitochondria may improve heart function during failure by increasing compensatory glucose oxidation. Adrenergic receptors (α₁ and β) are a key sympathetic nervous system regulator that controls cardiac function. β-AR blockers are an established treatment for heart failure and α_1A-AR agonists have potential therapeutic benefit. Besides regulating inotropy and chronotropy, α₁- and β-adrenergic receptors also regulate metabolic functions in the heart that underlie many cardiac benefits. This review will highlight recent studies that describe how adrenergic receptor-mediated metabolic pathways may be able to restore cardiac energetics to non-failing levels that may offer promising therapeutic strategies.

Intravenous Infusion of the β3-Adrenergic Receptor Antagonist APD418 Improves Left Ventricular Systolic Function in Dogs With Systolic Heart Failure

BACKGROUND

Unlike β₁- and β₂-adrenergic receptors (ARs), β₃-AR stimulation inhibits cardiac contractility and relaxation. In the failing left ventricular (LV) myocardium, β₃-ARs are upregulated, and can be maladaptive in the setting of decompensation by contributing to LV dysfunction. This study examined the effects of intravenous infusions of the β₃-AR antagonist APD418 on cardiovascular function and safety in dogs with systolic heart failure (HF).

METHODS AND RESULTS

Three separate studies were performed in 21 dogs with coronary microembolization-induced HF (LV ejection fraction [LVEF] of approximately 35%). Studies 1 and 2 (n = 7 dogs each) were APD418 dose escalation studies (dosing range, 0.35-15.00 mg/kg/h) designed to identify an effective dose of APD418 to be used in study 3. Study 3, the sustained efficacy study, (n = 7 dogs) was a 6-hour constant intravenous infusion of APD418 at a dose of 4.224 mg/kg (0.70 mg/kg/h) measuring key hemodynamic endpoints (e.g., EF, cardiac output, the time velocity integral of the mitral inflow velocity waveform representing early filling to time-velocity integral representing left atrial contraction [Ei/Ai]). Studies 1 and 2 showed a dose-dependent increase of LVEF and Ei/Ai, the latter being an index of LV diastolic function. In study 3, infusion of APD418 over 6 hours increased LVEF from 31 ± 1% to 38 ± 1% (P < .05) and increased Ei/Ai from 3.4 ± 0.4 to 4.9 ± 0.5 (P < .05). Vehicle had no effect on the LVEF or Ei/Ai. In study 3, APD418 had no significant effects on the HR or the systemic blood pressure.

CONCLUSIONS

Intravenous infusions of APD418 in dogs with systolic HF elicit significant positive inotropic and lusitropic effects. These findings support the development of APD418 for the in-hospital treatment of patients with an acute exacerbation of chronic HF.

The Beta3 Adrenergic Receptor in Healthy and Pathological Cardiovascular Tissues

The third isotype of beta-adrenoreceptors (β3-AR) has recently come (back) into focus after the observation of its expression in white and beige human adipocytes and its implication in metabolic regulation. This coincides with the recent development and marketing of agonists at the human receptor with superior specificity. Twenty years ago, however, we and others described the expression of β3-AR in human myocardium and its regulation of contractility and cardiac remodeling. Subsequent work from many laboratories has since expanded the characterization of β3-AR involvement in many aspects of cardiovascular physio(patho)logy, justifying the present effort to update current paradigms under the light of the most recent evidence.

Astaxanthin suppresses lipopolysaccharide‑induced myocardial injury by regulating MAPK and PI3K/AKT/mTOR/GSK3β signaling

Cardiac dysfunction is a significant manifestation of sepsis and it is associated with the prognosis of the disease. Astaxanthin (ATX) has been discovered to serve a variety of pharmacological effects, including anti‑inflammatory, antioxidant and antiapoptotic properties. The present study aimed to investigate the role and mechanisms of ATX in sepsis‑induced myocardial injury. Male C57BL/6 mice were divided into three groups (15 mice per group): Control group, lipopolysaccharide (LPS) group and LPS + ATX group. The cardiac dysfunction model was induced through an intraperitoneal injection of LPS (10 mg/kg) and ATX (40 mg/kg) was administered to the LPS + ATX group by intraperitoneal injection 30 min following the administration of LPS. All animals were sacrificed after 24 h. Inflammatory cytokine levels in the serum were detected using ELISAs, and cardiac B‑type natriuretic peptide (BNP) levels were analyzed using western blot analysis and reverse transcription‑quantitative PCR. Furthermore, the extent of myocardial injury was evaluated using pathological analysis, and cardiomyocyte apoptosis was analyzed using a TUNEL assay, in addition to determining the expression levels of Bcl‑2 and Bax. The expression levels of proteins involved in the mitogen activated protein kinase (MAPK) and PI3K/AKT signaling pathways were also analyzed using western blot analysis. ATX significantly suppressed the LPS‑induced increased production of TNF‑α and IL‑6 and suppressed the protein expression levels of BNP, Bax and Bcl‑2 to normal levels. ATX also prevented the histopathological changes to the myocardial tissue and reduced the extent of necrosis. Furthermore, the treatment with ATX suppressed the LPS‑activated MAPK and PI3K/AKT signaling. ATX additionally exerted a protective effect on cardiac dysfunction caused by sepsis by inhibiting MAPK and PI3K/AKT signaling.