Dexmedetomidine prevents septic myocardial dysfunction in rats via activation of α7nAChR and PI3K/Akt- mediated autophagy

Insight into Cardioprotective Effects and Mechanisms of Dexmedetomidine

PURPOSE

Cardiovascular disease remains the leading cause of death worldwide. Dexmedetomidine is a highly selective α2 adrenergic receptor agonist with sedative, analgesic, anxiolytic, and sympatholytic properties, and several studies have shown its possible protective effects in cardiac injury. The aim of this review is to further elucidate the underlying cardioprotective mechanisms of dexmedetomidine, thus suggesting its potential in the clinical management of cardiac injury.

RESULTS AND CONCLUSION

Our review summarizes the findings related to the involvement of dexmedetomidine in cardiac injury and discusses the results in the light of different mechanisms. We found that numerous mechanisms may contribute to the cardioprotective effects of dexmedetomidine, including the regulation of programmed cell death, autophagy and fibrosis, alleviation of inflammatory response, endothelial dysfunction and microcirculatory derangements, improvement of mitochondrial dysregulation, hemodynamics, and arrhythmias. Dexmedetomidine may play a promising and beneficial role in the treatment of cardiovascular disease.

Effectiveness of Dexmedetomidine as Myocardial Protector in Children With Classic Tetralogy of Fallot Having Corrective Surgery: A Randomized Controlled Trial

OBJECTIVES

Efficacy of dexmedetomidine (DEX) as a cardioprotective agent in Indonesian children undergoing classic tetralogy of Fallot (TOF) repair with cardiopulmonary bypass (CPB).

DESIGN

A prospective, parallel trial using block randomization along with double-blinded preparation of treatment agents by other parties.

SETTING

National Cardiovascular Center Harapan Kita, Indonesia.

PARTICIPANTS

Sixty-six children with classic TOF scheduled for corrective surgery. No children were excluded. All patients had fulfilled the criteria for analysis.

INTERVENTIONS

A total of 0.5 µg/kg bolus of DEX was added to the CPB priming solution, followed by 0.25 µg/kg/h maintenance during bypass. The placebo group used normal saline. Follow-ups were up to 30 days.

MEASUREMENTS AND MAIN RESULTS

Troponin I was lower in the DEX group at 6 hours (30.48 ± 19.33 v 42.73 ± 27.16, p = 0.039) and 24 hours after CPB (8.89 ± 5.42 v 14.04 ± 11.17, p = 0.02). Within a similar timeframe, DEX successfully lowered interleukin-6 (p = 0.03; p = 0.035, respectively). Lactate was lower in the Dex group at 1, 6, and 24 hours after CPB (p < 0.01; p = 0.048; p = 0.035; respectively). Dexmedetomidine increased cardiac output and index from 6 hours after bypass, but vice versa in systemic vascular resistance. Reduction of vasoactive inotropic score was seen during intensive care unit monitoring in the Dex group (p = 0.049). Nevertheless, DEX did not significantly affect the length of ventilation (p = 0.313), intensive care unit stay (p = 0.087), and mortality (p > 0.99).

CONCLUSIONS

Dexmedetomidine during CPB is an effective cardioprotective agent in TOF children having surgery. Postoperative mortality was comparable across groups.

Dose-dependent multi-organ injury following lipopolysaccharide gas inhalation

Lipopolysaccharide (LPS) is widely used to establish various animal models, including models of acute lung injury, cardiomyocyte damage, and acute kidney injury. Currently, there is no consensus on the diagnosis and treatment of LPS-induced disease. We herein present a case series of four patients who developed dose-dependent multi-organ injury, including acute lung injury and acute kidney injury, after inhaling LPS gas in a sealed room. These patients exhibited varying degrees of multi-organ injury characterized by inflammatory cell infiltration and secretion of proinflammatory cytokines. One patient showed progressive symptoms even with active treatment, leading to mild pulmonary fibrosis. This study emphasizes the importance of early diagnosis and treatment of significant LPS exposure and suggests personalized treatment approaches for managing LPS poisoning.

Combined administration of anisodamine and neostigmine alleviated colitis by inducing autophagy and inhibiting inflammation

Our previous work demonstrated that the anisodamine (ANI) and neostigmine (NEO) combination produced an antiseptic shock effect and rescued acute lethal crush syndrome by activating the α7 nicotinic acetylcholine receptor (α7nAChR). This study documents the therapeutic effect and underlying mechanisms of the ANI/NEO combination in dextran sulfate sodium (DSS)-induced colitis. Treating mice with ANI and NEO at a ratio of 500:1 alleviated the DSS-induced colitis symptoms, reduced body weight loss, improved the disease activity index, enhanced colon length, and alleviated colon inflammation. The combination treatment also enhanced autophagy in the colon of mice with DSS-induced colitis and lipopolysaccharide/DSS-stimulated Caco-2 cells. Besides, the ANI/NEO treatment significantly reduced INF-γ, TNF-α, IL-6, and IL-22 expression in colon tissues and decreased TNF-α, IL-1β, and IL-6 mRNA levels in Caco-2 cells. Meanwhile, the autophagy inhibitor 3-methyladenine and ATG5 siRNA attenuated these effects. Furthermore, 3-methyladenine (3-MA) and the α7nAChR antagonist methyllycaconitine (MLA) weakened the ANI/NEO-induced protection on DSS-induced colitis in mice. Overall, these results indicate that the ANI/NEO combination exerts therapeutic effects through autophagy and α7nAChR in a DSS-induced colitis mouse model.

Current insight on the mechanisms of programmed cell death in sepsis-induced myocardial dysfunction

Sepsis is a clinical syndrome characterized by a dysregulated host response to infection, leading to life-threatening organ dysfunction. It is a high-fatality condition associated with a complex interplay of immune and inflammatory responses that can cause severe harm to vital organs. Sepsis-induced myocardial injury (SIMI), as a severe complication of sepsis, significantly affects the prognosis of septic patients and shortens their survival time. For the sake of better administrating hospitalized patients with sepsis, it is necessary to understand the specific mechanisms of SIMI. To date, multiple studies have shown that programmed cell death (PCD) may play an essential role in myocardial injury in sepsis, offering new strategies and insights for the therapeutic aspects of SIMI. This review aims to elucidate the role of cardiomyocyte's programmed death in the pathophysiological mechanisms of SIMI, with a particular focus on the classical pathways, key molecules, and signaling transduction of PCD. It will explore the role of the cross-interaction between different patterns of PCD in SIMI, providing a new theoretical basis for multi-target treatments for SIMI.

Liver metabolomics reveals potential mechanism of Jieduan-Niwan formula against acute-on-chronic liver failure (ACLF) by improving mitochondrial damage and TCA cycle

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a refractory disease with high mortality, which is characterized by a pathophysiological process of inflammation-related dysfunction of energy metabolism. Jieduan-Niwan formula (JDNWF) is a eutherapeutic Chinese medicine formula for ACLF. However, the intrinsic mechanism of its anti-ACLF effect still need to be studied systematically.

PURPOSE

This study aimed to investigate the mechanism of JDNWF against ACLF based on altered substance metabolic profile in ACLF the expression levels of related molecules.

MATERIALS AND METHODS

The chemical characteristics of JDNWF were characterized using ultra performance liquid chromatography (UPLC) coupled with triple quadrupole mass spectrometry. Wistar rats subjected to a long-term CCL4 stimulation followed by a combination of an acute attack with LPS/D-GalN were used to establish the ACLF model. Liver metabolites were analyzed by LC-MS/MS and multivariate analysis. Liver function, coagulation function, histopathology, mitochondrial metabolic enzyme activity and mitochondrial damage markers were evaluated. The protein expression of mitochondrial quality control (MQC) was investigated by western blot.

RESULTS

Liver function, coagulation function, inflammation, oxidative stress and mitochondrial enzyme activity were significantly improved by JDNWF. 108 metabolites are considered as biomarkers of JDNWF in treating ACLF, which were closely related to TCA cycle. It was further suggested that JDNWF alleviated mitochondrial damage and MQC may be potential mechanism of JDNWF improving mitochondrial function.

CONCLUSIONS

Metabolomics revealed that TCA cycle was impaired in ACLF rats, and JDNWF had a regulatory effect on it. The potential mechanism may be improving the mitochondrial function through MQC pathway, thus restoring energy metabolism.

Effects of the PI3K/Akt/HO-1 pathway on autophagy in a sepsis-induced acute lung injury mouse model

Sepsis-induced lung injury is an acute hypoxic respiratory insufficiency caused by systemic infectious factors that results in alveolar epithelial cell and capillary endothelial cell injury, diffuse pulmonary interstitial edema, and alveolar edema. Heme oxygenase (HO)-1 is usually associated with inflammation and has anti-inflammatory effects. Autophagy is a degradation pathway that eliminates cellular metabolic waste and plays an important protective role during stress. The phosphatidylinositol 3-kinase/ protein kinase B (PI3K/Akt) signaling pathway plays a key role in mediating cellular responses to inflammatory reactions. Therefore, we hypothesized that HO-1 is associated with autophagy and regulated by the PI3K/Akt signaling pathway in mice with sepsis-induced lung injury. Sepsis-induced lung injury was induced in mice using cecal ligation and puncture (CLP). Hemin or Sn-protoporphyrin IX (SnPP) was administered via intraperitoneal injection before surgery. Survival rates were observed during days 1-7 after the surgery; lung histology was discerned 24 h after the surgery; pro-inflammatory and anti-inflammatory factors in plasma and lung tissue were measured using enzyme-linked immunosorbent assay (ELISA); HO-1, Beclin-1, microtubule-associated protein 1 light chain 3B (LC3B)-II, p62 and lysosome associated membrane protein (LAMP)2 protein expression levels were measured 24 h after the surgery; HO-1 and LC3B-II protein expression levels were observed using immunofluorescence 24 h after the surgery; and autophagosomes were detected using electron microscopy 24 h after the surgery. Furthermore, when PI3K inhibitors LY294002, PI3K activators Recilisib and hemin were administered before the surgery, Akt, p-Akt, HO-1, and LC3-II levels were measured 24 h post-surgery. We found that HO-1 overexpression increased the survival rate and inhibited sepsis-induced lung injury. HO-1 overexpression attenuated the levels of proinflammatory cytokines (TNF-α, IL-1β) and increased the anti-inflammatory cytokine (IL-10, HO-1) overexpression. Moreover, HO-1 overexpression was also associated with increased expression of Beclin-1, LC3B-II and LAMP2 protein expression; decreased p62 protein expression; and significantly increased autophagosome formation. The results for HO-1-downregulated mice contrasted with those mentioned above. LY294002 inhibited p-Akt/Akt, HO-1, and LC3B-II protein expression; and hemin reversed the inhibitory effect of LY294002. The protective effect of HO-1 was involved in the mediation of autophagy, which may be regulated by the PI3K/Akt signaling pathway during sepsis-induced lung injury in mice.

Dexmedetomidine as a myocardial protector in pediatric heart surgery using cardiopulmonary bypass: a systematic review

Background

In recent years, dexmedetomidine has been studied as a cardioprotective agent. However, studies on its application in pediatric heart surgery using cardiopulmonary bypass (CPB) remain limited. This systematic review aimed to provide information on the cardioprotective effect of dexmedetomidine in children undergoing heart surgery using CPB.

Methods

The authors searched several databases (MEDLINE, Embase, Cochrane Library, etc.) to identify all trials comparing the levels of myocardial injury via biomarkers, including pediatric patients undergoing heart surgery using CPB who received dexmedetomidine versus placebo or other anesthetic agents. Literatures from non-primary studies were excluded. Two reviewers independently screened studies for eligibility and extracted data. The Cochrane Risk-of-Bias tool was implemented to evaluate any potential biases. Information from eligible studies was summarized and correspondingly reviewed based on any quantitative outcomes.

Results

We identified six trials composed of 419 participants, three of which (n=241) showed significantly reduced interleukin-6 (IL-6) levels in the dexmedetomidine group, while one study (n=40) showed no IL-6 difference between groups. Cardiac troponin I (cTnI) and creatinine kinase-myocardial band (CK-MB), as myocardial injury biomarkers, were found to be lower in two trials (n=180). Despite several limitations hindering this review from pooling the data objectively, the majority of published studies indicated that dexmedetomidine is a seemingly efficacious agent protecting against cardiac injury during bypass.

Conclusions

These studies suggest that dexmedetomidine has cardioprotective effects through the lowering of cardiac injury biomarkers while improving its clinical outcomes after heart surgery using bypass.

NUCLEOLIN PROMOTES AUTOPHAGY THROUGH PGC-1Α IN LPS-INDUCED MYOCARDIAL INJURY

ABSTRACT

As a multifunctional protein, nucleolin can participate in a variety of cellular processes. Nucleolin also has multiple protective effects on heart disease. Previous studies have shown that nucleolin could not only resist oxidative stress damage and inflammatory damage, but also regulate autophagy to play a protective role in cardiac ischemia. However, the specific mechanism has not been fully elucidated in LPS-induced myocardial injury. Therefore, the aim of this study is to explore the underlying mechanism by which nucleolin regulates autophagy to protect against LPS-induced myocardial injury in vivo and in vitro . In our study, we found that nucleolin could bind to PGC-1α, and we predicted that this interaction could promote autophagy and played a role in inhibiting cardiomyocyte apoptosis. Downregulation of nucleolin in H9C2 cells resulted in decreased autophagy and increased cell apoptosis during LPS-induced myocardial injury, while upregulation of PGC-1α had the opposite protective effect. Upregulation of nucleolin expression in cardiomyocytes could increase the level of autophagy during LPS-induced myocardial injury. In contrast, interference with PGC-1α expression resulted in a decrease in the protective effect of nucleolin, leading to reduced autophagy and thus increasing apoptosis. By using tandem fluorescent-tagged LC3 autophagic flux detection system, we observed autophagic flux and determined that PGC-1α interference could block autophagic lysosomal progression. We further tested our hypothesis in the nucleolin cardiac-specific knockout mice. Finally, we also found that inhibition of autophagy can reduce mitochondrial biogenesis as well as increase apoptosis, which demonstrated the importance of autophagy. Therefore, we can speculate that nucleolin can protect LPS-induced myocardial injury by regulating autophagy, and this protective effect may be mediated by the interaction with PGC-1α, which can positively regulate the ULK1, an autophagy-related protein. Our study provides a new clue for the cardioprotective effect of nucleolin, and may provide new evidence for the treatment of LPS-induced myocardial injury through the regulation of autophagy.

Differential effects of dexmedetomidine on Gram-positive and Gram-negative bacterial killing and phagocytosis

Dexmedetomidine is a commonly used sedative in perioperative and intensive care settings with purported immunomodulatory properties. Since its effects on immune functions against infections have not been extensively studied, we tested the effects of dexmedetomidine on Gram-positive [Staphylococcus aureus and Enterococcus faecalis] and Gram-negative bacteria [Escherichia coli], and on effector functions of human monocytes THP-1 cells against them. We evaluated phagocytosis, reactive oxygen species (ROS) formation, and CD11b activation, and performed RNA sequencing analyses. Our study revealed that dexmedetomidine improved Gram-positive but mitigated Gram-negative bacterial phagocytosis and killing in THP-1 cells. The attenuation of Toll-like receptor 4 (TLR4) signaling by dexmedetomidine was previously reported. Thus, we tested TLR4 inhibitor TAK242. Similar to dexmedetomidine, TAK242 reduced E. coli phagocytosis but enhanced CD11b activation. The reduced TLR4 response potentially increases CD11b activation and ROS generation and subsequently enhances Gram-positive bacterial killing. Conversely, dexmedetomidine may inhibit the TLR4-signaling pathway and mitigate the alternative phagocytosis pathway induced by TLR4 activation through LPS-mediated Gram-negative bacteria, resulting in worsened bacterial loads. We also examined another α2 adrenergic agonist, xylazine. Because xylazine did not affect bacterial clearance, we proposed that dexmedetomidine may have an off-target effect on bacterial killing process, potentially involving crosstalk between CD11b and TLR4. Despite its potential to attenuate inflammation, we provide a novel insight into potential risks of dexmedetomidine use during Gram-negative infections, highlighting the differential effect of dexmedetomidine on Gram-positive and Gram-negative bacteria.

Fountain of youth—Targeting autophagy in aging

As our society ages inexorably, geroscience and research focusing on healthy aging is becoming increasingly urgent. Macroautophagy (referred to as autophagy), a highly conserved process of cellular clearance and rejuvenation has attracted much attention due to its universal role in organismal life and death. Growing evidence points to autophagy process as being one of the key players in the determination of lifespan and health. Autophagy inducing interventions show significant improvement in organismal lifespan demonstrated in several experimental models. In line with this, preclinical models of age-related neurodegenerative diseases demonstrate pathology modulating effect of autophagy induction, implicating its potential to treat such disorders. In humans this specific process seems to be more complex. Recent clinical trials of drugs targeting autophagy point out some beneficial effects for clinical use, although with limited effectiveness, while others fail to show any significant improvement. We propose that using more human-relevant preclinical models for testing drug efficacy would significantly improve clinical trial outcomes. Lastly, the review discusses the available cellular reprogramming techniques used to model neuronal autophagy and neurodegeneration while exploring the existing evidence of autophagy’s role in aging and pathogenesis in human-derived in vitro models such as embryonic stem cells (ESCs), induced pluripotent stem cell derived neurons (iPSC-neurons) or induced neurons (iNs).

Age-dependent roles of cardiac remodeling in sepsis defense and pathogenesis

Disease tolerance is a defense strategy essential for survival of infections, limiting physiological damage without killing the pathogen. The disease course and pathology a pathogen may cause can change over the lifespan of a host due to the structural and functional physiological changes that accumulate with age. Since successful disease tolerance responses require the host to engage mechanisms that are compatible with the disease course and pathology caused by an infection, we predicted that this defense strategy would change with age. Animals infected with a lethal dose 50 (LD50) of a pathogen often display distinct health and sickness trajectories due to differences in disease tolerance, and thus can be used to delineate tolerance mechanisms. Using a polymicrobial sepsis model, we found that despite having the same LD50, old and young susceptible mice exhibited distinct disease courses. Young survivors employed a cardioprotective mechanism via FoxO1-mediated regulation of the ubiquitin-proteosome system that was necessary for survival and protection from cardiomegaly. This same mechanism was a driver of sepsis pathogenesis in aged hosts, causing catabolic remodeling of the heart and death. Our findings have implications for the tailoring of therapy to the age of an infected individual and suggest that disease tolerance alleles may exhibit antagonistic pleiotropy.

Posttreatment with dexmedetomidine aggravates LPS-induced myocardial dysfunction partly via activating cardiac endothelial α2A-AR in mice

BACKGROUND

Dexmedetomidine (DEX) administered before or at 30 min after sepsis induction was reported to alleviate septic cardiomyopathy in experimental models. However, sepsis is a life-threatening organ dysfunction due to infection-induced dysregulated host response, whether DEX treatment in the presence of organ dysfunction affects septic cardiomyopathy is unknown. This study investigated the effect of DEX posttreatment on septic cardiomyopathy.

METHODS

Male wild-type and α_2A-adrenergic receptor (AR) knockout mice were exposed to lipopolysaccharide (LPS) or cecal ligation puncture (CLP), and cultured cardiac endothelial cells were used. Mouse survival, myocardial function, inflammatory response and related signaling pathways were determined.

RESULTS

DEX treatment at 6, 9 h after LPS challenge significantly reduced survival rate of LPS-challenged mice, especially at 9 h. DEX administered at 9 h after LPS injection or CLP significantly reduced survival in LPS or CLP-induced sepsis in wild-type mice, but not in α_2A-AR knockout mice. LPS treatment for 20 h decreased the left ventricle + dp/dt, increased myocardial interleukin (IL)-1β and IL-6 concentrations as well as cardiac endothelial tumor necrosis factor (TNF)-α, vascular cell adhesion molecule-1 (VCAM-1) and ICAM-1 expression, which were enhanced by DEX treated at 9 h after LPS injection in wild-type mice, but not in α_2A-AR knockout mice. Furthermore, DEX posttreatment increased p38 phosphorylation, c-Fos nuclear translocation and VCAM-1 expression in LPS-treated cardiac endothelial cells, which were eliminated by α_2A-AR knockout or PKC inhibitor.

CONCLUSIONS

DEX posttreatment aggravates LPS-induced cardiac inflammation and myocardial dysfunction, at least in part, via activating cardiac endothelial α_2A-AR-mediated PKC signal pathway.

Downregulated HDAC3 or up-regulated microRNA-296-5p alleviates diabetic retinopathy in a mouse model

Objective

It has been demonstrated the efficacy of histone deacetylase 3 (HDAC3) in diabetes. Nevertheless, the function of HDAC3 in diabetic retinopathy (DR) remained largely obscure. Here, we investigated the HDAC3 effects in DR mice through the microRNA (miR)-296-5p/G protein subunit alpha i2 (GNAI2) axis.

Methods

The mice diabetes model was established. HDAC3, GNAI2 and miR-296-5p levels in retina tissues of DR mice were evaluated. The weight, blood glucose, Evans blue leakage in DR mice, apoptosis of retinal ganglion cells, vascular endothelial growth factor (VEGF) and malondialdehyde (MDA) contents and superoxide dismutase (SOD) activity in DR mice were detected after miR-296-5p elevation or HDAC3 depletion. The relations among HDAC3, miR-296-5p and GNAI2 were validated.

Results

HDAC3 and GNAI2 expressed at a high level while miR-296-5p expressed at a low level in retina tissues of DR mice. Restoring miR-296-5p or depleting HDAC3 reduced Evans blue leakage in DR mice, attenuated apoptosis of retinal ganglion cells, reduced VEGF and MDA, and enhanced SOD activity in serum and retinal tissues of DR mice. HDAC3 repressed miR-296-5p expression by binding to its promoter region, thereby enhancing GNAI2 expression.

Conclusion

Depleting HDAC3 or restoring miR-296-5p suppresses apoptosis of retinal ganglion cells of DR mice via down-regulating GNAI2.

Dexmedetomidine attenuates renal ischemia-reperfusion injury through activating PI3K/Akt-eNOS signaling via α2 adrenoreceptors in renal microvascular endothelial cells

Renal microvascular endothelial cells (RMECs), which are closely related to regulation of vascular reactivity and modulation of inflammation, play a crucial role in the process of renal ischemia and reperfusion (I/R) injury. Previous studies have reported the protective effects of dexmedetomidine (DEX) against renal I/R injury, but little is known about the role of DEX on RMECs. This study aimed to investigate whether DEX alleviated renal I/R injury via acting on the RMECs. Mice underwent bilateral renal artery clamping for 45 min followed by reperfusion for 48 h, and the cultured neonatal mice RMECs were subjected to hypoxia for 1 h followed by reoxygenation (H/R) for 24 h. The results suggest that DEX alleviated renal I/R injury in vivo and improved cell viability of RMECs during H/R injury in vitro. Gene sequencing revealed that the PI3K/Akt was the top enriched signaling pathway and the endothelial cells were widely involved in renal I/R injury. DEX activated phosphorylation of PI3K and Akt, increased eNOS expression, and attenuated inflammatory responses. In addition, the results confirmed the distribution of α₂ adrenoreceptor (α₂ -AR) in RMECs. Furthermore, the protective effects of DEX against renal I/R injury were abolished by α₂ -AR antagonist (atipamezole), which was partly reversed by the PI3K agonist (740 Y-P). These findings indicated that DEX protects against renal I/R injury by activating the PI3K/Akt-eNOS pathway and inhibiting inflammation responses via α₂ -AR in RMECs.

Dexmedetomidine attenuates lipopolysaccharide-induced inflammation through macrophageal IL-10 expression following α7 nAchR activation

Dexmedetomidine, a highly selective α₂-adrenoceptor agonist, has been recently reported to alleviate systemic inflammatory response induced by lipopolysaccharide (LPS), in addition to its sedative, analgesic, bradycardic and hypotensive properties. This study aimed to illustrate the molecular mechanisms underlying dexmedetomidine-induced anti-inflammation. In the LPS-pretreated mice, subcutaneous injection of dexmedetomidine reduced the spleen weight as well as serum and spleen expression of proinflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1β, and increased serum and spleen expression of IL-10, a known anti-inflammatory cytokine. In addition, dexmedetomidine-attenuated proinflammatory cytokine reduction was entirely inhibited by selective α7 nicotinic acetylcholine receptor (nAChR) antagonist methyllycaconitine but not α₂-adrenoceptor antagonist yohimbine. Dexmedetomidine also increased macrophageal IL-10 expression in the presence and absence of LPS, which was also attenuated by methyllycaconitine but not yohimbine. Furthermore, the stimulatory effect of dexmedetomidine on the expression of IL-10 was also reduced by the α7 nAChR gene silencer siRNA/α7 nAChR. Lastly, pretreatment with the IL-10 neutralizing antibody reversed dexmedetomidine-supressed expression of proinflammatory cytokines. Our findings illustrate that dexmedetomidine-induced anti-inflammation is through macrophageal expression of IL-10 following activation of α7 nAchRs but not α₂-adrenoceptors.

Cardiomyocyte death in sepsis: Mechanisms and regulation (Review)

Sepsis‑induced cardiac dysfunction is one of the most common types of organ dysfunction in sepsis; its pathogenesis is highly complex and not yet fully understood. Cardiomyocytes serve a key role in the pathophysiology of cardiac function; due to the limited ability of cardiomyocytes to regenerate, their loss contributes to decreased cardiac function. The activation of inflammatory signalling pathways affects cardiomyocyte function and modes of cardiomyocyte death in sepsis. Prevention of cardiomyocyte death is an important therapeutic strategy for sepsis‑induced cardiac dysfunction. Thus, understanding the signalling pathways that activate cardiomyocyte death and cross‑regulation between death modes are key to finding therapeutic targets. The present review focused on advances in understanding of sepsis‑induced cardiomyocyte death pathways, including apoptosis, necroptosis, mitochondria‑mediated necrosis, pyroptosis, ferroptosis and autophagy. The present review summarizes the effect of inflammatory activation on cardiomyocyte death mechanisms, the diversity of regulatory mechanisms and cross‑regulation between death modes and the effect on cardiac function in sepsis to provide a theoretical basis for treatment of sepsis‑induced cardiac dysfunction.

Research Progress on the Mechanism of Sepsis Induced Myocardial Injury

Sepsis is an abnormal condition with multiple organ dysfunctions caused by the uncontrolled infection response and one of the major diseases that seriously hang over global human health. Besides, sepsis is characterized by high morbidity and mortality, especially in intensive care unit (ICU). Among the numerous subsequent organ injuries of sepsis, myocardial injury is one of the most common complications and the main cause of death in septic patients. To better manage septic inpatients, it is necessary to understand the specific mechanisms of sepsis induced myocardial injury (SIMI). Therefore, this review will elucidate the pathophysiology of SIMI from the following certain mechanisms: apoptosis, mitochondrial damage, autophagy, excessive inflammatory response, oxidative stress and pyroptosis, and outline current therapeutic strategies and potential approaches in SIMI.

Protective effects of dexmedetomidine in vital organ injury: crucial roles of autophagy

Vital organ injury is one of the leading causes of global deaths. Accumulating studies have demonstrated that dexmedetomidine (DEX) has an outstanding protective effect on multiple organs for its antiinflammatory and antiapoptotic properties, while the underlying molecular mechanism is not clearly understood. Autophagy, an adaptive catabolic process, has been found to play a crucial role in the organ-protective effects of DEX. Herein, we present a first attempt to summarize all the evidence on the proposed roles of autophagy in the action of DEX protecting against vital organ injuries via a comprehensive review. We found that most of the relevant studies (17/24, 71%) demonstrated that the modulation of autophagy was inhibited under the treatment of DEX on vital organ injuries (e.g. brain, heart, kidney, and lung), but several studies suggested that the level of autophagy was dramatically increased after administration of DEX. Albeit not fully elucidated, the underlying mechanisms governing the roles of autophagy involve the antiapoptotic properties, inhibiting inflammatory response, removing damaged mitochondria, and reducing oxidative stress, which might be facilitated by the interaction with multiple associated genes (i.e., hypoxia inducible factor-1α, p62, caspase-3, heat shock 70 kDa protein, and microRNAs) and signaling cascades (i.e., mammalian target of rapamycin, nuclear factor-kappa B, and c-Jun N-terminal kinases pathway). The authors conclude that DEX hints at a promising strategy in the management of vital organ injuries, while autophagy is crucially involved in the protective effect of DEX.

The cardioprotective effects of perindopril in a model of polymicrobial sepsis: The role of radical oxygen species and the inflammation pathway

Mortality rates associated with myocardial dysfunction due to sepsis and septic shock are generally high across the world. The present study focused on the antioxidant and anti-inflammatory effects of perindopril (PER) for the purpose of preventing the adverse effects of sepsis on the myocardium and developing new alternatives in treatment. The control group received only saline solution via the oral route for 4 days. The second group underwent cecal ligation puncture (CLP), and the third underwent CLP and received PER (2 mg/kg). Rats in the third group received 2 mg/kg PER per oral (p.o.) from 4 days before induction of sepsis. Thiobarbituric acid reactive species (TBARS), total thiol (-SH), interleukin-1 beta (IL-1β), IL-6, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and nuclear factor kappa B (NF-κB/p65) levels increased in the CLP groups. In contrast, PER (2 mg/kg) decreased the levels of biochemical parameters other than total-SH and decreased 8-OHdG, NF-κB/p65 immunopositivity in rat heart tissues. The data from this study show that impairment of the oxidant/antioxidant balance and inflammatory cytokine levels in favor of inflammation in heart tissue under septic conditions results in severe tissue damage. PER administration before sepsis was shown to exhibit antioxidant and anti-inflammatory properties by reducing these effects. This in turn increased the importance of PER as new evidence of its protective effects in heart tissue.

Clemastine protects against sepsis-induced myocardial injury in vivo and in vitro

Sepsis-induced myocardial dysfunction (SIMD) is associated with high morbidity and mortality rates; however, it lacks targeted therapies. Modulating cardiomyocyte autophagy maintains intracellular homeostasis during SIMD. Clemastine, a histamine receptor inhibitor, promotes autophagy and other effective biological functions. Nevertheless, the effect of clemastine on SIMD remains unclear. This study aimed to explore the underlying mechanism of clemastine in cardiomyocyte injury in cecum ligation and perforation (CLP)-induced rats and lipopolysaccharide (LPS)-stimulated H9c2 cells. Clemastine (10 mg/kg, 30 mg/kg, and 50 mg/kg) was intraperitoneally injected after 30 min of CLP surgery. Serum cTnI levels and the 7-day survival rate were evaluated. Echocardiograms and H&E staining were used to evaluate cardiac function and structure. TEM was used to detect the mitochondrial ultrastructure and autophagosomes. Clemastine significantly improved the survival rate and reduced cTnI production in serum. Clemastine ameliorated cellular apoptosis, improved mitochondrial ultrastructure both in vivo and in vitro, increased ATP content, decreased dynamin-related protein 1 (DRP1) expression, and decreased mitochondrial ROS levels. Additionally, clemastine treatment increased autophagosome concentration, LC3II/LC3I rate, and Beclin 1 expression. However, 3-methyladenine (3-MA), an autophagy inhibitor, could abolish the effect of clemastine on alleviating myocardial apoptosis. In conclusion, clemastine protected against cardiac structure destruction and function dysfunction, mitochondrial damage, apoptosis, and autophagy in vivo and in vitro. Moreover, clemastine attenuated myocardial apoptosis by promoting autophagy. This study provides a novel favorable perspective for SIMD therapy.

Effect of Dexmedetomidine on Tachyarrhythmias After Cardiac Surgery: A Systematic Review and Meta-Analysis

ABSTRACT

Tachyarrhythmias after cardiac surgery is a common occurrence in clinical practice, which can be life threatening. We searched 6 databases, including Embase, PubMed, Cochrane, CNKI, Wanfang, and Sinomed, to evaluate the effect of dexmedetomidine on tachyarrhythmias after adult cardiac surgery. The primary end point was the number of patients with atrial fibrillation (AF) after cardiac surgery. The secondary end points included the number of patients with supraventricular tachycardia or with ventricular tachycardia or with ventricular fibrillation or with myocardial infarction or deceased patients, the duration of mechanical ventilation, the intensive care unit stay, hospital stay, and the number of patients with bradycardia and those with hypotension. Among the 1388 retrieved studies, 18 studies (n = 3171 participants) met our inclusion criteria. Dexmedetomidine reduced the incidence of AF by 17% [relative risk (RR) = 0.83; 95% confidence interval (CI), 0.73-0.93; P = 0.002]. Through subgroup analysis, we found that when the maintenance dose of dexmedetomidine was >0.7 µg·kg-1·h-1, the effect of preventing AF was obvious (RR = 0.58; 95%CI 0.43-0.78; P = 0.0003). Dexmedetomidine also reduced the incidence of supraventricular tachycardia by approximately 70% (RR = 0.29; 95% CI, 0.11-0.77; P = 0.01) and the incidence of ventricular tachycardia by approximately 80% (RR = 0.23; 95% CI, 0.08-0.63; P = 0.004) but had no effect on ventricular fibrillation (RR = 1.02; 95% CI, 0.14-7.31; P = 0.99). The major side effect of dexmedetomidine was bradycardia. Dexmedetomidine can reduce the incidence of AF (especially high dosages), supraventricular tachycardia, and ventricular tachycardia after cardiac surgery in adults, but it does not affect the occurrence of ventricular fibrillation.

Long non-coding RNA MALAT1 silencing elevates microRNA-26a-5p to ameliorate myocardial injury in sepsis by reducing regulator of calcineurin 2

OBJECTIVE

Sepsis is a leading cause of morbidity and mortality after surgery. We aimed to explore the role of long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) sponging microRNA-26a-5p in sepsis-induced myocardial injury by regulating regulator of calcineurin 2 (Rcan2).

METHODS

HL-1 cells were incubated with lipopolysaccharide (LPS) to induce in vitro cardiomyocyte injury models, which were then treated with silenced MALAT1 vector, miR-26a-5p mimic or Rcan2 overexpression vector. Next, inflammatory factor level and apoptosis of cells were determined. The in vivo mouse models were constructed by intraperitoneal injection of LPS. The modeled mice were injected with relative oligonucleotides and the pathology, apoptosis, and inflammation in mouse myocardial tissues were assessed. Expression of MALAT1, miR-26a-5p and Rcan2 in vivo and in vitro was evaluated.

RESULTS

MALAT1 and Rcan2 were upregulated while miR-26a-5p was downregulated in LPS-treated HL-1 cells and mice. MALAT1 silencing or miR-26a-5p upregulation suppressed LPS-induced inflammation and apoptosis of cardiomyocytes in cellular and animal models. These effects of elevated miR-26a-5p could be reversed by upregulating Rcan2, and MALAT1 knockdown-induced ameliorative impacts could be reversed by miR-26a-5p downregulation.

CONCLUSION

MALAT1 silencing elevated miR-26a-5p to ameliorate LPS-induced myocardial injury by reducing Rcan2. Our research may provide novel biomarkers for the treatment of sepsis.

Recent Advances in the Clinical Value and Potential of Dexmedetomidine

Dexmedetomidine, a highly selective α2-adrenoceptor agonist, has sedative, anxiolytic, analgesic, sympatholytic, and opioid-sparing properties and induces a unique sedative response which shows an easy transition from sleep to wakefulness, thus allowing a patient to be cooperative and communicative when stimulated. Recent studies indicate several emerging clinical applications via different routes. We review recent data on dexmedetomidine studies, particularly exploring the varying routes of administration, experimental implications, clinical effects, and comparative advantages over other drugs. A search was conducted on the PubMed and Web of Science libraries for recent studies using different combinations of the words “dexmedetomidine”, “route of administration”, and pharmacological effect. The current routes, pharmacological effects, and application categories of dexmedetomidine are presented. It functions by stimulating pre- and post-synaptic α2-adrenoreceptors within the central nervous system, leading to hyperpolarization of noradrenergic neurons, induction of an inhibitory feedback loop, and reduction of norepinephrine secretion, causing a sympatholytic effect, in addition to its anti-inflammation, sleep induction, bowel recovery, and sore throat reduction effects. Compared with similar α2-adrenoceptor agonists, dexmedetomidine has both pharmacodynamics advantage of a significantly greater α2:α1-adrenoceptor affinity ratio and a pharmacokinetic advantage of having a significantly shorter elimination half-life. In its clinical application, dexmedetomidine has been reported to present a significant number of benefits including safe sedation for various surgical interventions, improvement of intraoperative and postoperative analgesia, sedation for compromised airways without respiratory depression, nephroprotection and stability of hypotensive hemodynamics, reduction of postoperative nausea and vomiting and postoperative shivering incidence, and decrease of intraoperative blood loss. Although the clinical application of dexmedetomidine is promising, it is still limited and further research is required to enhance understanding of its pharmacological properties, patient selection, dosage, and adverse effects.

Protective Effects of Dexmedetomidine on Sepsis-Induced Vascular Leakage by Alleviating Ferroptosis via Regulating Metabolic Reprogramming

Introduction

Vascular leakage plays a vital role in sepsis-induced multi-organ dysfunction. Currently, no specific measures are available for vascular leakage. Ferroptosis, as a recently recognized form of cell death, plays a crucial role in cell dysfunction. It is still unknown whether ferroptosis participates in the occurrence of organ dysfunction following sepsis. Our previous study showed that dexmedetomidine (Dex) could alleviate sepsis-induced organ dysfunction. However, whether the mechanism is related to ferroptosis is not clear.

Methods

The publicly available datasets of septic patients were reanalyzed, and septic models in vivo and vitro by cecal ligation and puncture and lipopolysaccharide-stimulated vascular endothelial cells (VECs) were applied. The occurrence of ferroptosis in septic patients and rats was observed, and the protective effects of Dex on ferroptosis, and related mechanisms on regulating metabolic reprogramming and mitochondrial fission were further studied.

Results

The transcriptomics data of patients from the GEO database showed that ferroptosis was closely related to sepsis. Sepsis induced significant ferroptosis in VECs by metabolomics analysis. The level of lipid peroxidation was increased in VECs, and the mitochondrial cristae was decreased after sepsis. Metabolomics analysis showed that Dex activated the pentose phosphate pathway and increased glutathione in VECs via up-regulation of G6PD expression. Dex could antagonize sepsis-induced the decrease in the level of Nrf2. The Nrf2 inhibitor reversed the protective effect of Dex on ferroptosis. Further study showed that Dex significantly alleviated sepsis-induced mitochondrial over-division, improved mitochondrial function, and decreased ROS, further inhibiting the ferroptosis of VECs. Dex alleviated the permeability of vessels by reducing ferroptosis and enhanced the intercellular junction of VECs.

Conclusion

Dex protects vascular leakage following sepsis by inhibiting ferroptosis. The mechanism is mainly related to metabolic reprogramming via Nrf2 up-regulation and inhibition of mitochondrial fission.

The Protective Mechanism of Dexmedetomidine in Regulating Atg14L-Beclin1-Vps34 Complex Against Myocardial Ischemia-Reperfusion Injury

The blood flow restoration of ischemic tissues causes myocardial injury. Dexmedetomidine (Dex) protects multi-organs against ischemia/reperfusion (I/R) injury. This study investigated the protective mechanism of Dex post-treatment in myocardial I/R injury. The rat model of myocardial I/R was established. The effects of Dex post-treatment on cardiac function and autophagy flow were observed. Dex attenuated myocardial I/R injury and reduced I/R-induced autophagy in rats. Dex weakened the interactions between Beclin1 and Vps34 and Beclin1 and Atg14L, thus downregulating Vps34 kinase activity. In vitro, the cardiomyocytes subjected to oxygen glucose deprivation/reoxygenation were treated with Dex and PI3K inhibitor LY294002. LY294002 attenuated the myocardial protective effect of DEX, indicating that Dex protected against cardiac I/R by activating the PI3K/Akt pathway. In conclusion, Dex upregulated the phosphorylation of Beclin1 at S295 site by activating the PI3K/Akt pathway and reduced the interactions of Atg14L-Beclin1-Vps34 complex, thus inhibiting autophagy and protecting against myocardial I/R injury.

Impact of intravenous dexmedetomidine on postoperative bowel movement recovery after laparoscopic nephrectomy: A consort-prospective, randomized, controlled trial

BACKGROUND

Postoperative ileus is a frequent postoperative complication, especially after abdominal surgery. Sympathetic excitation is the primary factor for postoperative ileus. Sympathetic activation becomes increased by surgical stress, postoperative pain, and inflammation. Dexmedetomidine (DEX) can inhibit sympathetic nerve activity, inflammation, and pain.

AIM

To observe whether DEX promotes bowel movements in patients after laparoscopic nephrectomy.

METHODS

One hundred and twenty patients undergoing laparoscopic nephrectomy were assigned to three groups: C (normal saline infusion), D1 (DEX 0.02 µg/kg/h), and D2 (DEX 0.04 µg/kg/h). The primary outcomes were the recorded times to first flatus, defecation, and eating after surgery. The secondary outcomes were postoperative pain, assessed using the numerical rating scale (NRS), adverse effects, and the duration of the postoperative hospital stay.

RESULTS

The times to first flatus, defecation, and eating in groups D1 and D2 were significantly shorter than those in group C (P < 0.01). The NRS scores at 8 h and 24 h after surgery were significantly lower in groups D1 and D2 than in group C (P < 0.05). No adverse effects were observed (P > 0.05).

CONCLUSION

Postoperative infusion of DEX at 0.04 µg/kg/h facilitates bowel movements in patients undergoing laparoscopic nephrectomy.

microRNA-193-3p attenuates myocardial injury of mice with sepsis via STAT3/HMGB1 axis

Objective

Little is known regarding the functional role of microRNA-193-3p (miR-193-3p) in sepsis. Hence, the aim of the present study was to investigate the effect of miR-193-3p on myocardial injury in mice with sepsis and its mechanism through the regulation of signal transducers and activators of transcription 3 (STAT3).

Methods

The mice model of sepsis was established by cecal ligation and puncture (CLP), septic mice were injected with miR-193-3p agomir, miR-193-3p antagomir or siRNA-STAT3. The expression of miR-193-3p, STAT3 and HMGB1 in the myocardial tissue of septic mice were detected. Cardiac ultrasound, hemodynamics, myocardial injury markers, inflammatory factors and cardiomyocyte apoptosis in septic mice were measured.

Results

MiR-193-3p expression was reduced while STAT3 expression was increased in septic mice. Down-regulated STAT3 or up-regulated miR-193-3p improved cardiac function, attenuated myocardial injury, inflammation and cardiomyocyte apoptosis in septic mice. Knockdown STAT3 reversed the role of inhibited miR-193-3p for mice with sepsis. miR-193-3p targeted STAT3, thereby inhibiting HMGB1 expression.

Conclusion

This study provides evidence that miR-193-3p targets STAT3 expression to reduce HMGB1 expression, thereby reducing septic myocardial damage. MiR-193-3p might be a potential candidate marker and therapeutic target for sepsis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03022-x.

miR‑214 ameliorates sepsis‑induced acute kidney injury via PTEN/AKT/mTOR‑regulated autophagy

Previous studies have suggested that oxidative stress and autophagy results in acute kidney injury (AKI) during sepsis and microRNA (miR)-214 serves a vital role in the protection of kidneys subjected to oxidative stress. The present study aimed to test whether the renoprotection of miR-214 is related to autophagy in sepsis. The role of autophagy was investigated in a mouse model of cecal ligation and puncture (CLP). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to analyze the expression of miR-214. The structure and function of kidneys harvested from the mice were evaluated. Kidney autophagy levels were detected with immunohistochemical, immunofluorescent and western blotting. It was found that miR-214 could alleviate AKI in septic mice by inhibiting the level of kidney autophagy. Furthermore, miR-214 inhibited autophagy by silencing PTEN expression in the kidney tissues of septic mice. These findings indicated that miR-214 ameliorated CLP-induced AKI by reducing oxidative stress and inhibiting autophagy through the regulation of the PTEN/AKT/mTOR pathway.

Dexmedetomidine alleviates cardiomyocyte apoptosis and cardiac dysfunction may be associated with inhibition of RhoA/ROCK pathway in mice with myocardial infarction

The global incidence of myocardial infarction has been consistently high, and it is one of the main causes of poor cardiovascular prognosis. Dexmedetomidine (DEX) is a highly selective α2 receptor agonist. Recent studies have found that DEX has a protective effect on myocardial infarction, but its specific mechanism is still unclear. In this experiment, we permanently ligated the anterior descending branch of mice to explore the protective mechanism of DEX against myocardial infarction. Our study found that intraperitoneal injection of DEX for 7 days after myocardial infarction in mice can increase the reduction of ejection fraction (EF) and fractional shortening (FS) caused by myocardial infarction and significantly reduce the release of serum markers. The results of myocardial HE and Sirius red staining suggest that the changes in the myocardial structure of mice after using DEX are reduced. Immunohistochemistry shows that DEX reduces the expression of ROCK1 protein after myocardial infarction. TUNEL staining and the protein expression levels of cleaved caspase-3 and cleaved caspase-9 were used to detect cell apoptosis and results make clear that DEX can reduce the apoptosis caused by myocardial infarction. Western blot experiments showed that DEX can reduce the expression levels of ROCK1 and ROCK2 (Rho-kinase). At the same time, it was observed that DEX improved the Bcl-2/Bax ratio. The above results indicate that DEX reduces cardiomyocyte apoptosis and improves cardiac function likely through inhibiting the RhoA/ROCK signaling pathway. This study may provide new insights into the protective effect of DEX after myocardial infarction in mice.

Melatonin Alleviates Cardiac Dysfunction Via Increasing Sirt1-Mediated Beclin-1 Deacetylation and Autophagy During Sepsis

Cardiac dysfunction is a major cause leading to multiple organ failure in sepsis. Beclin-1-dependent autophagy has been evidenced to exert protective effects on hearts in sepsis. However, the mechanisms on how Beclin-1 and autophagy are regulated remains enigmatic. To explore the detailed mechanisms controlling Beclin-1-dependent autophagy in septic heart and whether melatonin could protect against sepsis via regulating cardiac autophagy, adult Sprague-Dawley (SD) rats were subjected to cecal ligation and puncture (CLP) to induce sepsis. Rats were intraperitoneally administrated with 30 mg/kg melatonin within 5-min post-CLP surgery. Our data showed that sepsis induced Becline-1 acetylation and inhibited autophagy in hearts, resulting in impaired cardiac function. However, melatonin treatment facilitated Beclin-1 deacetylation and increased autophagy in septic hearts, thus improved cardiac function. Moreover, melatonin increased the expression and activity of Sirtuin 1 (Sirt1), and inhibition of Sirt1 abolished the protective effects of melatonin on Beclin-1 deacetylation and cardiac function. In conclusion, increased Beclin-1 acetylation was involved in impaired autophagy in septic hearts, while melatonin contributed to Beclin-1 deacetylation via Sirt1, leading to improved autophagy and cardiac function in sepsis. Our study sheds light on the important role of Beclin-1 acetylation in regulating autophagy in sepsis and suggests that melatonin is a potential candidate drug for the treatment of sepsis.

Adiponectin Attenuates Lipopolysaccharide-induced Apoptosis by Regulating the Cx43/PI3K/AKT Pathway

Cardiomyocyte apoptosis is a crucial factor leading to myocardial dysfunction. Adiponectin (APN) has a cardiomyocyte-protective impact. Studies have shown that the connexin43 (Cx43) and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathways play an important role in the heart, but whether APN plays a protective role by regulating these pathways is unclear. Our study aimed to confirm whether APN protects against lipopolysaccharide (LPS)-induced cardiomyocyte apoptosis and to explore whether it plays an important role through regulating the Cx43 and PI3K/AKT signaling pathways. In addition, our research aimed to explore the relationship between the Cx43 and PI3K/AKT signaling pathways. In vitro experiments: Before H9c2 cells were treated with LPS for 24 h, they were pre-treated with APN for 2 h. The cytotoxic effect of APN on H9c2 cells was evaluated by a CCK-8 assay. The protein levels of Bax, Bcl2, cleaved caspase-3, cleaved caspase-9, Cx43, PI3K, p-PI3K, AKT and p-AKT were evaluated by Western blot analysis, and the apoptosis rate was evaluated by flow cytometry. APN attenuated the cytotoxicity induced by LPS. LPS upregulated Bax, cleaved caspase-3 and cleaved caspase-9 and downregulated Bcl2 in H9c2 cells; however, these effects were attenuated by APN. In addition, LPS upregulated Cx43 expression, and APN downregulated Cx43 expression and activated the PI3K/AKT signaling pathway. LPS induced apoptosis and inhibited PI3K/AKT signaling pathway in H9c2 cells, and these effects were attenuated by Gap26 (a Cx43 inhibitor). Moreover, the preservation of APN expression was reversed by LY294002 (a PI3K/AKT signaling pathway inhibitor). In vivo experiments: In C57BL/6J mice, a sepsis model was established by intraperitoneal injection of LPS, and APN was injected into enterocoelia. The protein levels of Bax, Bcl2, cleaved caspase-3, and Cx43 were evaluated by Western blot analysis, and immunohistochemistry was used to detect Cx43 expression and localization in myocardial tissue. LPS upregulated Bax and cleaved caspase-3 and downregulated Bcl2 in sepsis; however, these effects were attenuated by APN. In addition, the expression of Cx43 was upregulated in septic myocardial tissue, and APN downregulated Cx43 expression in septic myocardial tissue. In conclusion, both in vitro and in vivo, the data demonstrated that APN can protect against LPS-induced apoptosis during sepsis by modifying the Cx43 and PI3K/AKT signaling pathways.

Dexmedetomidine Protects Against Septic Liver Injury by Enhancing Autophagy Through Activation of the AMPK/SIRT1 Signaling Pathway

Background: Liver injury is one of the serious complications of sepsis. Previous studies suggested that dexmedetomidine (DEX) could alleviate cecal ligation and puncture (CLP)-induced liver injury. However, it is unclear whether the protective effect of DEX on sepsis-induced liver injury is related to autophagy.

Methods: Mice (n = 105) were randomly divided into the following groups: (i) CON group (Sham); (ii) CLP group (CLP-induced liver injury + saline); (iii) CLP + DEX group (CLP-induced liver injury + DEX). Mouse models of sepsis-induced liver injury were established using CLP. DEX or normal saline was administered by intraperitoneal injection at 0, 2, and 4 h after CLP surgery. The mortality rate within 120 h was calculated. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and inflammatory cytokines were measured at 6, 12, and 24 h in each group. Hematoxylin and eosin staining assay was carried out to detect the morphological changes of mouse liver cells in each group. The levels of autophagy-associated proteins LC3II, Beclin-1, p62, and LAMP-2 were detected in three groups of mice using western blotting. The expression of LC3II was detected using immunofluorescence. Transmission electron microscopy (TEM) of liver tissue was used to observe autophagosomes and autophagosome–lysosomes. Lastly, the effect of DEX on the AMPK/SIRT1 pathway-associated protein levels were detected using western blotting. Meanwhile, we used L0-2 cells infected with mRFP-GFP-LC3 adenovirus to further analyze the role of SIRT1 in DEX-induced autophagy in liver injury model in vitro.

Results: DEX significantly improved the survival rate of septic mice at the early stage and ameliorated the pathology of sepsis-induced liver injury. The level of autophagy-associated proteins, phosphorylated (p)-AMPK/AMPK, and SIRT1 in the liver of CLP-induced sepsis mice peaked at 12 h post-CLP and decreased significantly at 24 h. In the CLP + DEX group, the levels of autophagy-associated proteins, p-AMPK/AMPK, and SIRT1 increased, whereas inflammatory cytokines decreased at 24 h. The autophagosome structure was clearly observed at different time points in the CLP + DEX group. In the in vitro hepatocyte injury model, the SIRT1 inhibitor significantly increased intracellular ROS levels and reversed the effect of DEX on autophagy flux.

Conclusion: We demonstrated a novel mechanism in which DEX protects against CLP-induced liver injury. DEX enhances autophagy, which alleviates the inflammatory responses in CLP-induced liver injury by regulating the SIRT1/AMPK pathway.

Cartilage endplate stem cells inhibit intervertebral disc degeneration by releasing exosomes to nucleus pulposus cells to activate Akt/autophagy

Degeneration of the cartilage endplate (CEP) induces intervertebral disc degeneration (IVDD). Nucleus pulposus cell (NPC) apoptosis is also an important exacerbating factor in IVDD, but the cascade mechanism in IVDD is not clear. We investigated the apoptosis of NPCs and IVDD when stimulated by normal cartilage endplate stem cell (CESC)-derived exosomes (N-Exos) and degenerated CESC-derived exosomes (D-Exos) in vitro and in vivo. Tert-butyl hydroperoxide (TBHP) was used to induce inflammation of CESCs. The bioinformatics differences between N-Exos and D-Exos were analyzed using mass spectrometry, heat map, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. NPC apoptosis was examined using TUNEL staining. The involvement of the AKT and autophagy signaling pathways was investigated using the signaling inhibitor LY294002. Magnetic resonance imaging, Western blotting, and immunofluorescence staining were used to evaluate the therapeutic effects of N-Exos in rats with IVDD. TBHP effectively induced inflammation and the degeneration of CEP in rat. N-Exos were more conducive to autophagy activation than D-Exos. The apoptotic rate of NPCs decreased obviously after treatment with N-Exos compared to D-Exos. N-Exos inhibited NPCs apoptosis and attenuated IVDD in rat via activation of the AKT and autophagy pathways. These results are the first findings to confirm that CEP delayed the progression of IVDD via exosomes. The therapeutic effects of N-Exos on NPC apoptosis inhibition and the slowing of IVDD progression were more effective than D-Exos due to activation of the PI3K/AKT/autophagy pathway, which explained the increase in the incidence of IVDD after inflammation of the CEP.

Dexmedetomidine Attenuates Ischemia/Reperfusion-Induced Myocardial Inflammation and Apoptosis Through Inhibiting Endoplasmic Reticulum Stress Signaling

Background

Endoplasmic reticulum stress (ERS)-mediated myocardial inflammation and apoptosis plays an important role in myocardial ischemia/reperfusion (I/R) injury. Dexmedetomidine has been used clinically with sedative, analgesic, and anti-inflammatory properties. This study aimed to determine the effects of dexmedetomidine pretreatment on inflammation, apoptosis, and the expression of ERS signaling during myocardial I/R injury.

Methods

Rats underwent myocardial ischemia for 30 min and reperfusion for 6 h, and H9c2 cardiomyocytes were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) injury (OGD for 12 h and reoxygenation for 3 h). Dexmedetomidine was administered prior to myocardial ischemia in rats or ODG in cardiomyocytes. In addition, the α2-adrenergic receptor antagonist (yohimbine) or the PERK activator (CCT020312) was given prior to dexmedetomidine treatment.

Results

Dexmedetomidine pretreatment decreased serum levels of cardiac troponin I, reduced myocardial infarct size, alleviated histological structure damage, and improved left ventricular function following myocardial I/R injury in rats. In addition, dexmedetomidine pretreatment increased cell viability and reduced cytotoxicity following OGD/R injury in cardiomyocytes. Mechanistically, the cardioprotection offered by dexmedetomidine was mediated via the inhibition of inflammation and apoptosis through downregulating the expression of the ERS signaling pathway, including glucose-regulated protein 78 (GRP78), protein kinase R-like endoplasmic reticulum kinase (PERK), C/EBP homologous protein (CHOP), inositol-requiring protein 1 (IRE1), and activating transcription factor 6 (ATF6). Conversely, the protective effects of dexmedetomidine were diminished by blocking the α2 adrenergic receptors with yohimbine or promoting PERK phosphorylation with CCT020312.

Conclusion

Dexmedetomidine pretreatment protects the hearts against I/R injury via inhibiting inflammation and apoptosis through downregulation of the ERS signaling pathway. Future clinical studies are needed to confirm the cardioprotective effects of dexmedetomidine in patients at risk of myocardial I/R injury.

LncRNA HOTAIR Promotes LPS-Induced Inflammation and Apoptosis of Cardiomyocytes via Lin28-Mediated PDCD4 Stability

Sepsis is one of the primary causes of death in intensive care units. Recently, increasing evidence has identified lncRNA HOTAIR is involved in septic cardiomyopathy. However, the potential mechanism underlying HOTAIR on septic cardiomyopathy is still unknown. H9C2 cells were treated with lipopolysaccharide (LPS) after transfection with sh-HOTAIR, sh-Lin28, pcDNA3.1-HOTAIR, and pcDNA3.1-PDCD4. qRT-PCR was used to examine the level of HOTAIR, Lin28, PDCD4, and sepsis-related inflammatory cytokines. Flow cytometric analysis was applied to detect cell apoptosis. The interaction between Lin28 and HOTAIR or PDCD4 was verified by RNA pull-down and RIP assay. HOTAIR levels were interfered by AAV9-sh-HOTAIR in LPS-induced septic cardiomyopathy mice. ELISA analysis was used to evaluate TNF-α, IL-6, and IL-1β level. Western blot was used to detect the expression of LIN28 and PDCD4 in mouse cardiomyocytes. Echocardiography was used to evaluate the cardiac function. In our study, knockdown of HOTAIR inhibited LPS-induced inflammation and H9C2 cells apoptosis. HOTAIR promoted LPS-induced inflammatory response and apoptosis of H9C2 cells by enhancing PDCD4 stability. RNA pull-down and RIP assay exhibited that Lin28, a highly conserved RNA-binding protein, was combined with HOTAIR and PDCD4. The in vivo experiments verified that the HOTAIR knockdown alleviated the cardiac function injury and secretion of inflammatory factors caused by sepsis. In conclusion, our findings supported that the HOTAIR/Lin28/PDCD4 axis serves as a critical regulator of sepsis, which may open a new direction for the development of sepsis therapeutic.

The role of the cholinergic anti-inflammatory pathway in septic cardiomyopathy

Septic cardiomyopathy (SCM)is common in septic patients and results in cardiovascular failure. The pathogenesis of SCM is complicated, and patients with SCM have high mortality because current treatment methods are limited. The cholinergic anti-inflammatory pathway (CAP) modulates inflammatory responses through vagus nerve stimulation that leads to the release of acetylcholine (ACh), which binds to the alpha7 nicotinic acetylcholine receptor (α7nAChR). Moreover, α7nAChR activation by its agonists at the tissue level inhibits inflammatory mediators and regulates the function of immune cells in sepsis. Therefore, the α7nAChR can maintain balance of the inflammatory-immune response in sepsis. CAP has been elucidated as a critical regulator of anti-inflammation in many diseases, including rheumatoid arthritis, inflammatory boweldisease and SCM. Additionally, some clinical and preclinical trials show therapeutic potential via regulating CAP. There are excellent studies regarding the beneficial role of CAP activation, especially α7nAChR, in experimental SCM. This review aims to discuss the CAP in attenuating inflammation and the potential role of α7nAChR activation in regulating immune and reducing inflammation in SCM.

Pharmacological and cardiovascular perspectives on the treatment of COVID-19 with chloroquine derivatives

The novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19) and an ongoing severe pandemic. Curative drugs specific for COVID-19 are currently lacking. Chloroquine phosphate and its derivative hydroxychloroquine, which have been used in the treatment and prevention of malaria and autoimmune diseases for decades, were found to inhibit SARS-CoV-2 infection with high potency in vitro and have shown clinical and virologic benefits in COVID-19 patients. Therefore, chloroquine phosphate was first used in the treatment of COVID-19 in China. Later, under a limited emergency-use authorization from the FDA, hydroxychloroquine in combination with azithromycin was used to treat COVID-19 patients in the USA, although the mechanisms of the anti-COVID-19 effects remain unclear. Preliminary outcomes from clinical trials in several countries have generated controversial results. The desperation to control the pandemic overrode the concerns regarding the serious adverse effects of chloroquine derivatives and combination drugs, including lethal arrhythmias and cardiomyopathy. The risks of these treatments have become more complex as a result of findings that COVID-19 is actually a multisystem disease. While respiratory symptoms are the major clinical manifestations, cardiovascular abnormalities, including arrhythmias, myocarditis, heart failure, and ischemic stroke, have been reported in a significant number of COVID-19 patients. Patients with preexisting cardiovascular conditions (hypertension, arrhythmias, etc.) are at increased risk of severe COVID-19 and death. From pharmacological and cardiovascular perspectives, therefore, the treatment of COVID-19 with chloroquine and its derivatives should be systematically evaluated, and patients should be routinely monitored for cardiovascular conditions to prevent lethal adverse events.

Metabolomics approach based on utra-performance liquid chromatography coupled to mass spectrometry with chemometrics methods for high-throughput analysis of metabolite biomarkers to explore the abnormal metabolic pathways associated with myocardial dysfunction

Ultra-performance liquid chromatography/mass spectrometry-based metabolomics can been used for discovery of metabolite biomarkers to explore the metabolic pathway of diseases. Identification of metabolic pathways is key to understanding the pathogenesis and mechanism of disease. Myocardial dysfunction induced by sepsis (SMD) is a severe complication of septic shock and represents major causes of death in intensive care units; however its pathological mechanism is still not clear. In this study, ultrahigh-pressure liquid chromatography with mass spectrometry-based metabolomics with chemometrics anaylsis and multivariate pattern recognition analysis were used to detect urinary metabolic profile changes in a lipopolysaccharide-induced SMD mouse model. Multivariate statistical analysis including principal component analysis and orthogonapartial least squares discriminant analysis for the discrimination of SMD was conducted to identify potential biomarkers. A total of 19 differential metabolites were discovered by high-resolution mass spectrometry-based urinary metabolomics strategy. The altered biochemical pathways based on these metabolites showed that tyrosine metabolism, phenylalanine metabolism, ubiquinone biosynthesis and vitamin B6 metabolism were closely connected to the pathological processes of SMD. Consequently, integrated chemometric analyses of these metabolic pathways are necessary to extract information for the discovery of novel insights into the pathogenesis of disease.

Exercise Preconditioning Plays a Protective Role in Exhaustive Rats by Activating the PI3K-Akt Signaling Pathway

Objective

To investigate whether exercise preconditioning (EP) protects the rat heart from exhaustive exercise- (EE-) induced injury by inducing the PI3K-Akt signaling pathway.

Methods

84 male Sprague-Dawley rats were randomly divided into 6 groups (n = 14 rats per group): control group (Con), exhaustive exercise group (EE), exercise preconditioning group (EP), exercise preconditioning + exhaustive exercise group (EP + EE), LY294002 (PI3K inhibitor) + exercise preconditioning + exhaustive exercise group (LY + EP + EE), and LY294002 group (LY). The Con and LY did not exercise. The remaining groups were subjected to treadmill running. The structure of myocardial tissue and serum biomarkers of myocardial injury were observed. Hemodynamic parameters were recorded with a pressure-volume catheter. TUNEL assay was used to detect the apoptosis of cardiac myocytes, and the level of mitochondrial membrane permeability transforming pore (mPTP) in myocardium was evaluated using ELISA. Pathway and apoptosis-related proteins in myocardium were assessed using western blotting.

Results

Compared to the Con group, the EE group showed remarkable myocardial injury, such as cardiac dysfunction and myocardial apoptosis. Compared to the EE group, the injuries in the EP + EE group were improved. EP increased the PI3K-Akt signaling pathway and regulated Bcl-2 family to decrease the mPTP openness level. However, the cardioprotective effects of EP were attenuated when pretreated with the LY294002.

Conclusions

EP protected the heart from EE-induced injury, and it may improve the cardiac function and reduce the cardiomyocyte apoptosis by activating the PI3K-Akt signaling pathway.