LPS-induced Myocardial Injury Research Articles

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.

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

ObjectiveSepsis 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). MethodsHL-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. ResultsMALAT1 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. ConclusionMALAT1 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.

Paeoniflorin improves myocardial injury via p38 MAPK/NF-KB p65 inhibition in lipopolysaccharide-induced mouse.

BackgroundPaeoniflorin (Pae) is an active compound with a variety of pharmacological effects. This aim was to investigate how Pae protects against myocardial injury and to explore its potential mechanism.MethodsWe established a BALB/c mouse model that was intraperitoneal injection (i.p.) of RvE1 (25 µg/kg) or Pae (20 mg/kg) for 3 days, and then treated with lipopolysaccharide (LPS, 10 mg/kg, i.p.). The mice were randomly divided into the sham group, the LPS group, the LPS + RvE1 group, the LPS + Pae group (n=8). Cardiac dysfunction was detected by HE staining and ELISA assay. The oxidative stress, mitochondrial membrane potential (MMP), mitochondrial permeability transition pore (mPTP) and apoptosis were assessed. Furthermore, western blotting (WB) assay were employed to analyze the protective mechanisms.ResultsPae improved LPS-induced cardiac function and impeded apoptosis. Pae significantly reduced the release of inflammatory cytokines such as interleukin (IL)-6, tumor necrosis factor-α (TNF-α), and IL-1β. Furthermore, Pae decreased malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species (ROS), and increased superoxide dismutase (SOD). In addition, Pae attenuated the mPTP opening and MMP depolarization. Notably, Pae treatment inhibited the activation of p38 MAPK and NF-κB p65.ConclusionsIt was confirmed that Pae alleviated LPS-induced myocardial injury. Pae might be as a new drug candidate for myocardial ischaemic complications.

Dioscin attenuates lipopolysaccharide-induced inflammatory myocardial injury through oxidative stress-related pathway

Lipopolysaccharide (LPS) is one of the main causes of myocardial injury. Dioscin has a protective effect on myocardial injury induced by LPS; however, the biological function and mechanism remain unclear. The purpose of this study was to investigate the effect of dioscin on myocardial injury induced by LPS. The myocardial injury model was constructed through LPS treatment of primary rat cardiomyocytes. Cardiomyocytes were treated with different concentrations of dioscin (50, 100, and 200 ng/mL). MTT was used to detect the activity of cardiomyocytes; flow cytometry and TUNEL assay were used to detect apoptosis; and enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). The release of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) was detected according to the kit instructions. The levels of apoptosis-related proteins (Bax, caspase-3, and Bcl 2) and the Nrf2-Keap1 pathway proteins were detected by western blot. Dioscin significantly reduced LPS-induced cardiomyocyte injury in neonatal rats in a concentration- and time-dependent manner. Dioscin also significantly inhibited cardiomyocyte inflammation and apoptosis induced by LPS. With the increase of dioscin concentration, reactive oxygen species (ROS) and MDA were downregulated, and SOD and GSH were upregulated. Moreover, dioscin inhibited LPS-induced myocardial injury by inhibiting the Nrf2-Keap1 pathway. Our study suggests that dioscin attenuates LPS-induced myocardial injury through oxidative stress-related pathways.

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.

Selective inhibition of PKCβ2 improves Caveolin-3/eNOS signaling and attenuates lipopolysaccharide-induced injury by inhibiting autophagy in H9C2 cardiomyocytes.

Lipopolysaccharide (LPS)-induced autophagy is involved in sepsis-associated myocardial injury with increased PKCβ2 activation. We previously found hyperglycemia-induced PKCβ2 activation impaired the expression of caveolin-3 (Cav-3), the dominant isoform to form cardiomyocytes caveolae which modulate eNOS signaling to confer cardioprotection in diabetes. However, little is known about the roles of PKCβ2 in autophagy and Cav-3/eNOS signaling in cardiomyocytes during LPS exposure. We hypothesize LPS-induced PKCβ2 activation promotes autophagy and impairs Cav-3/eNOS signaling in LPS-treated cardiomyocytes. H9C2 cardiomyocytes were treated with LPS (10µg/mL) in the presence or absence of PKCβ2 inhibitor CGP53353 (CGP, 1µM) or autophagy inhibitor 3-methyladenine (3-MA, 10µM). LPS stimulation induced cytotoxicity overtime in H9C2 cardiomyocytes, accompanied with excessive PKCβ2 activation. Selective inhibition of PKCβ2 with CGP significantly reduced LPS-induced cytotoxicity and autophagy (measured by LC-3II, Beclin-1, p62 and autophagic flux). In addition, CGP significantly attenuated LPS-induced oxidative injury, and improved Cav-3 expression and eNOS activation, similar effects were shown by the treatment of autophagy inhibitor 3-MA. LPS-induced myocardial injury is associated with excessive PKCβ2 activation, which contributes to elevated autophagy and impaired Cav-3/eNOS signaling. Selective inhibition of PKCβ2 improves Cav-3/eNOS signaling and attenuates LPS-induced injury through inhibiting autophagy in H9C2 cardiomyocytes.

Overexpression of miR-365a-3p relieves sepsis-induced acute myocardial injury by targeting MyD88/NF-κB pathway.

Sepsis often leads to systemic multiple organ dysfunction, with the majority of deaths attributable to acute myocardial injury (AMI). In this study, we aimed to explore the functional role of miR-365a-3p in sepsis-induced AMI. The sepsis myocardial injury model was constructed using lipopolysaccharide (LPS) both in vitro and in vivo with selective regulation of miR-365a-3p expression. Real-time PCR or Western blot was employed to detect the expressions of miR-365a-3p, inflammatory cytokines (tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and IL-6), and inflammation-related proteins (nuclear factor-κB (NF-κB), I-κB, myeloid differentiation factor 88 (MyD88)) in myocardial tissues and cells. Also, cell counting kit-8 (CCK8) and flow cytometry assays were used to measure cardiomyocyte proliferation and apoptosis, respectively. Furthermore, the targeting relationship between miR-365a-3p and MyD88 was verified with the dual luciferase activity assay. miR-365a-3p was downregulated in LPS-induced myocardial injury model. miR-365a-3p overexpression attenuated cardiomyocyte apoptosis and suppressed the expressions of inflammatory cytokines and proteins. Inhibiting miR-365a-3p, however, produced the opposite effects. Mechanistically, miR-365a-3p targeted the 3'-untranslated region of MyD88, thereby inactivating MyD88-mediated NF-κB pathway. miR-365a-3p overexpression mitigated sepsis-mediated myocardial injury by inhibiting MyD88-mediated NF-κB activation.

Silencing of CREB Inhibits HDAC2/TLR4/NF-κB Cascade to Relieve Severe Acute Pancreatitis-Induced Myocardial Injury.

The purpose of the present study is to investigate the role of CREB in cardiomyocytes proliferation in regulation of HDAC2-dependent TLR4/NF-κB pathway in severe acute pancreatitis (SAP)-induced myocardial injury. The SAP rat model was developed by injecting sodium touracholate into SD rats and then infected with lentivirus vectors expressing sh-CREB in the presence/absence of LPS. The pathological alterations of rat pancreatic and cardiac tissues were observed by HE staining. TUNEL assay was used to study apoptosis of cardiomyocytes. Next, the loss- and gain-function assay was conducted in LPS-induced myocardial injury cardiomyocytes to define the roles of CREB, HDAC2, and TLR4 in cardiomyocyte proliferation, apoptosis, inflammation, and myocardial injury in vitro. ChIP assay was used to study the enrichment of CREB bound to HDAC2 promoter. RT-qPCR and Western blot analysis were used to detect the expressions of related mRNA and proteins in the NF-κB pathway, respectively. CREB was found to be overexpressed in both SAP tissues and cells. CREB directly bound to the promoter of HDAC2 and activated its expression. Overexpressed CREB or HDAC2 inhibited proliferation and promoted apoptosis of cardiomyocytes. Suppression of CREB inhibited the HDAC2/TLR4/NF-κB cascade to promote proliferation and inhibit apoptosis of cardiomyocytes. The in vitro results were validated in vivo experiments. Coherently, suppression of CREB can inhibit HDAC2/TLR4/NF-κB cascade to promote cardiomyocyte proliferation, thus ameliorating SAP-induced myocardial injury.

Melatonin alleviates lipopolysaccharide-induced myocardial injury by inhibiting inflammation and pyroptosis in cardiomyocytes.

BackgroundMelatonin (MT) has been shown to protect against various cardiovascular diseases. However, the effect of MT on lipopolysaccharide (LPS)-induced myocardial injury is poorly understood. This study aims to evaluate the effects of MT on LPS-induced myocardial injury in vitro.MethodsH9C2 cells were divided into a control group, MT group, LPS group, and MT + LPS group. The control group was treated with sterile saline solution, the LPS group received 8 µg/mL LPS for 24 h, MT + LPS cells were pretreated with 200 µmol/L MT for 2 h then with 8 µg/mL LPS for 24 h, and the MT group received only 200 µmol/L MT for 2 h. The CCK-8 assay and lactate dehydrogenase (LDH) activity assay were used to analyze cell viability and LDH release, respectively. Intracellular reactive oxygen species (ROS) and the rate of pyroptosis were measured using the fluorescent probe dichloro-dihydro-fluorescein diacetate (DCFH-DA) and propidium iodide (PI) staining, respectively. The cell supernatants were used to measure the levels of inflammatory cytokines, including IL-6, TNF-α, and IL-1β by enzyme-linked immunosorbent assay (ELISA). The protein levels of iNOS, COX-2, NF-κB, p-NF-κB, NLRP3, caspase-1, and GSDMD were detected by western blot.ResultsMT pretreatment significantly improved LPS-induced myocardial injury by inhibiting inflammation and pyroptosis in H9C2 cells. Moreover, MT inhibited the activation of the NF-κB pathway, and reduced the expression of inflammation-related proteins (iNOS and COX-2), and pyroptosis-related proteins (NLRP3, caspase-1, and GSDMD).ConclusionsOur data suggests that MT can alleviate LPS-induced myocardial injury, providing novel insights into the treatment of sepsis-induced myocardial dysfunction.

Shikonin Ameliorates LPS-Induced Cardiac Dysfunction by SIRT1-Dependent Inhibition of NLRP3 Inflammasome.

Shikonin (SHI) is an anti-inflammatory agent extracted from natural herbs. It is still unknown whether SHI ameliorates lipopolysaccharide (LPS)-induced cardiac dysfunction. This study aims to explore the protective effects of SHI on LPS-induced myocardial injury and its mechanism. The LPS-induced cardiac dysfunction mouse model was employed to investigate the protective effects of SHI. In the present study, we found that SHI treatment improved the survival rate and cardiac function and remarkably ameliorated the release of inflammatory cytokines and macrophage infiltration in heart tissue of LPS-treated mice. SHI also reduced lactate dehydrogenase (LDH) and cardiac troponin (cTn) release, cell inflammation, and apoptosis in LPS plus adenosine triphosphate (ATP)-treated H9c2 cells. In addition, SHI significantly upregulated silent information regulator 1 (SIRT1) expression and suppressed the upregulation of NOD-like receptor protein 3 (NLRP3), cleaved caspase-1, and caspase-1 activity in heart tissues induced by LPS. Meanwhile, we got the same results in LPS plus ATP-treated H9c2 cells in vitro. Further, SIRT1 inhibitor or siRNA partially blocked SHI-mediated upregulation of SIRT1 expression and downregulation of NLRP3, cleaved caspase-1, and caspase-1 activity in heart tissues induced by LPS. Therefore, we conclude that SHI ameliorates LPS-induced cardiac dysfunction by inhibiting SIRT1-dependent activation of NLRP3 inflammasomes and might be a promising therapeutic strategy for the treatment of LPS-induced cardiac dysfunction.

Selenium Supplementation Protects Against Lipopolysaccharide-Induced Heart Injury via Sting Pathway in Mice.

Sepsis-induced myocardial dysfunctions are associated with high morbidity and mortality. Selenium, an essential trace element, has been reported to exert anti-inflammation, anti-oxidative stress, and anti-apoptosis. However, the protective effects of selenium on LPS-induced heart injury are still poorly illustrated. Therefore, in the present study, we sought to explore the effects of selenium pretreatment on LPS-induced myocardial injury in mice. We firstly found that selenium pretreatment significantly improved markers of myocardial injury and alleviated LPS-induced myocardial dysfunctions. Moreover, selenium supplementation reduced pro-inflammatory cytokines expression, decreased oxidative stress, and inhibited myocardial apoptosis. In addition, selenium supplementation inactivated the Sting pathway. In conclusion, our study suggests that selenium exerts protective effects on LPS-induced myocardial injury, and the underlying molecular mechanism may be related to the inactivation of Sting pathway, implying a potential therapy for sepsis-induced myocardial dysfunctions.

LncRNA MIAT Promotes Inflammation and Oxidative Stress in Sepsis-Induced Cardiac Injury by Targeting miR-330-5p/TRAF6/NF-κB Axis.

Sepsis is a whole-body inflammation and main cause of death in intensive care units worldwide. We aimed to investigate the roles of lncRNA MIAT and miR-330-5p in modulating inflammatory responses and oxidative stress in lipopolysachariden (LPS)-induced septic cardiomyopathy. Serum and heart tissue were collected from in vivo septic mice model, ELISA and qRT-PCR were used to measure the expression of pro-inflammation cytokines, MIAT and miR-330-5p, respectively. The knockdown of MIAT and overexpression of miR-330-5p were conducted to assess their effects on regulating inflammation response and intracellular oxidative stress in LPS-stimulated HL-1 cells. The reactive oxygen (ROS) level, mitochondrial membrane potential (MMP), GSH/GSSH ratio, and lipid peroxidation assessment (MDA) were used to evaluate the intracellular oxidative stress. Dual-luciferase reporter assay was performed to identify the association between MIAT and miR-330-5p, TRAF6 and miR-330-5p, respectively. In septic mice, the expression of MIAT and pro-inflammation cytokines was elevated while the expression of miR-330-5p decreased. Knockdown of MIAT or overexpression of miR-330-5p restrained inflammation and oxidative stress induced by LPS in vitro; MIAT directly targeted miR-330-5p to regulate NF-κB signaling, and miR-330-5p targeted against TRAF6 to suppress the activation of NF-κB signaling. We determined that lncRNA MIAT directly binds to miR-330-5p to activate TRAF6/NF-κB signaling axis and further promotes inflammation response as well as oxidative stress in LPS-induced septic cardiomyopathy. This finding suggests the potential therapeutic role of lncRNA MIAT and miR-330-5p in LPS-induced myocardial injury.

MiR-16 exhibits protective function in LPS-treated cardiomyocytes by targeting DOCK2 to repress cell apoptosis and exert anti-inflammatory effect.

This study aims to investigate the effects of microRNA (miR)-16/dedicator of cytokinesis 2 (DOCK2) on myocarditis. The differences in the expression of genes in acute myocarditis were filtered out across Gene Expression Omnibus (GEO) database. Myocarditis cell model was established by lipopolysaccharide (LPS) stimulation in cardiomyocytes. The association between miR-16 and DOCK2 was predicted by bioinformatics software and confirmed by dual-luciferase assay. Polymerase chain reaction and western blot analysis were employed to assess the expression levels of miR-16 and DOCK2 under different conditions. Cells viability, apoptosis, and inflammatory reaction were evaluated by Cell Counting Kit-8, flow cytometry, and enzyme-linked immunosorbent assays. miR-16, as an upstream regulator of DOCK2, exhibited lower expression in LPS-induced myocarditis model. More importantly, we revealed that a marked augmentation of miR-16 promoted the growth of LPS-stimulated cardiomyocytes, and attenuated cell apoptosis and inflammatory response. However, an increasing expression of DOCK2 inhibited the remission of LPS-induced myocardial injury caused by miR-16 mimic. Herein, our results highlighted that upregulation of miR-16 resulted in the protective effects on LPS-induced myocardial injury by reducing DOCK2 expression, affording a pair of novel target molecules for ameliorating the symptoms of myocarditis.

The Protective Effects of Melatonin Against LPS-Induced Septic Myocardial Injury: A Potential Role of AMPK-Mediated Autophagy.

Aim: Melatonin is an indolamine secreted by the pineal gland, as well as most of the organs and tissues. In addition to regulating circadian biology, studies have confirmed the multiple pharmacological effects of melatonin. Melatonin provides a strong defense against septic myocardial injury. However, the underlying mechanism has not been fully described. In this study, we investigated the protective effects of melatonin against lipopolysaccharide (LPS)-induced myocardial injury as well as the mechanisms involved.Methods: Mice were intraperitoneally injected with LPS to induce a septic myocardial injury model or an LPS shock model, depending on the dose of LPS. Melatonin was given (20 mg/kg/day, via intraperitoneal injection) for a week prior to LPS insult. 6 h after LPS injection, echocardiographic analysis, TUNEL staining, transmission electron microscopy (TEM), western blot, quantitative real-time PCR and ELISA were used to investigate the protective effects of melatonin against LPS induced myocardial injury. AMPK inhibitor, autophagy activator and inhibitor, siRNAs were used for further validation.Results: Survival test showed that melatonin significantly increased the survival rate after LPS-induced shock. In the sepsis model, melatonin markedly ameliorated myocardial dysfunction, decreased the release of inflammatory cytokines, activated AMP-activated protein kinase (AMPK), improved mitochondrial function, and activated autophagy. To confirm whether the protection of melatonin was mediated by AMPK and autophagy, Compound C, an AMPK inhibitor; 3-MA, an autophagy inhibitor; and Rapamycin (Rapa), an autophagy activator, were used in this study. AMPK inhibition down-regulated autophagy, abolished protection of melatonin, as indicated by significantly decreased cardiac function, increased inflammation and damaged mitochondrial function. Furthermore, autophagy inhibition by 3-MA significantly impaired the protective effects of melatonin, whereas autophagy activation by Rapa reversed LPS + Compound C induced myocardial injury. In addition, in vitro studies further confirmed the protection of melatonin against LPS-induced myocardial injury and the mechanisms involving AMPK-mediated autophagy signaling.Conclusions: In summary, our results demonstrated that melatonin protects against LPS-induced septic myocardial injury by activating AMPK mediated autophagy pathway.

LncRNA NEAT1 promotes the progression of sepsis-induced myocardial cell injury by sponging miR-144-3p.

Sepsis is a systemic inflammatory response that can lead to the dysfunction of many organs, including the cardiac one. Long noncoding RNAs (lncRNAs) have been shown to be involved in multiple organ injuries induced by sepsis. However, the regulatory effect of nuclear enriched abundant transcript 1 (NEAT1) on sepsis-induced myocardial injury remains to be explored. The sepsis models of myocardial cell injury were constructed using lipopolysaccharide (LPS). Cell counting kit-8 (CCK-8) assay was used to detect cell viability. Flow cytometry was performed to assess cell apoptosis. Moreover, the levels of apoptosis-related and nuclear factor-kappa B (NF-κB) signaling pathway-related proteins were evaluated by Western blot (WB) analysis. Besides, the contents of inflammatory cytokines were tested by enzyme-linked immunosorbent assay (ELISA). The expression levels of NEAT1 and microRNA-144-3p (miR-144-3p) were determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). In addition, Dual-Luciferase reporter and RNA immunoprecipitation (RIP) assays were used to verify the interaction between NEAT1 and miR-144-3p. LPS could induce myocardial cell injury to construct sepsis models. NEAT1 was upregulated in LPS-treated myocardial cells, and its knockdown promoted viability, suppressed apoptosis, and relieved inflammatory response in LPS-induced myocardial cell injury. MiR-144-3p was downregulated in LPS-treated myocardial cells, and the effect of its overexpression on LPS-induced myocardial cell injury was similar to the effect of NEAT1 knockdown. Besides, miR-144-3p could be sponged by NEAT1, and its inhibitor could reverse the effect of NEAT1 knockdown on LPS-induced myocardial cell injury. Moreover, NEAT1 and miR-144-3p could regulate the activity of NF-κB signaling pathway. LncRNA NEAT1 could interact with miR-144-3p to regulate sepsis-induced myocardial cell injury through the NF-κB signaling pathway, which might provide a new theoretical basis for the study on the effect of sepsis treatment.

Down-regulation of Xist and Mir-7a-5p improves LPS-induced myocardial injury.

Background: X-inactive specific transcript (Xist) is a lncRNA, which plays a significant role in X-chromosome inactivation, regulates cell proliferation in tumor cells, and inhibits apoptosis in acute myocardial infarction. On the other hand, miR-7a-5p is involved in cardiomyocytes injury in myocardial ischemia/reperfusion. However, their roles in LPS-induced damage remain unclear.Objectives: This study aimed at using siRNA transfection and lentivirus infection to regulate the expression of xist and miR-7a-5p, and to evaluate their effects on LPS-induced myocardial damage.Method: Mice cardiomyocytes (MCM) cells were divided into six groups, namely the control group, the LPS group, the LPS + lncRNA- group, the LPS + lncRNA+ group, the LPS + miRNA- group, and the LPS + miRNA+ group. Quantitative real-time PCR (qRT-PCR) was performed to assay for the RNA expressions of xist, miR-7a-5p, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), and recombinant mitochondrial transcription factor A (Tfam) in all the groups. The ATP level was determined using the adenosine triphosphate (ATP) assay kit according to the manufacturer's instructions. Flow cytometry was performed to estimate the level of apoptosis and proliferation in cells in each group.Results: The level of xist in the myocardial cells was markedly higher in the LPS group compared with the control group; however, it was reduced in the LPS+ lncRNA- group. There was no significant difference in the expression of xist among the LPS+miRNA-, LPS+miRNA+, and LPS groups. Moreover, the expression of mir-7a-5p was significantly reduced in myocardial cells in the LPS group, and moderately reduced in the LPS+ miRNA- group, but remarkably elevated in the LPS+ miRNA+ group (P<0.05). The expression of mir-7a-5p was comparably similar in the LPS+ lncRNA- group, LPS+ lncRNA+ group, and LPS groups. Further, the levels of PGC-1a, and Tfam were determined. In the LPS group, the expression of PGC-1α was significantly reduced but elevated in the LPS+lncRNA- and LPS+ miRNA- groups (P<0.05). There was no significant difference in the level of PGC-1α among the LPS, LPS+ lncRNA+, and LPS+ miRNA+ groups. The expression of Tfam was markedly reduced in the LPS group (P < 0.05), but elevated after the suppression of xist and mir-7a-5p. The expression of Tfam was not significantly different among the LPS group, LPS+ lncRNA+ and LPS+ miRNA+ groups. Notably, overexpression of mir-7a-5p had a mild effect on the expression of Tfam in the LPS+ miRNA+ group compared with the control group. Besides, ATP expression in the LPS group was markedly reduced, but elevated after the inhibition of xist and mir-7a-5p. Suppressing the expression of xist or mir-7a-5p resulted in reduced cell apoptosis and increased cell proliferation.Conclusions: In this study, we established that down-regulation of xist and mir-7a-5p reduces apoptosis in response to LPS.

LncRNA NEAT1 alleviates sepsis-induced myocardial injury by regulating the TLR2/NF-κB signaling pathway.

To investigate the effect of long non-coding ribonucleic acid nuclear paraspeckle assembly transcript 1 (lncRNA NEAT1) on lipopolysaccharide (LPS)-induced myocardial injury in mice and the underlying mechanism. This study aims to provide some references for the prevention and treatment of sepsis-induced myocardial injury. According to the random number table, 60 male C57 mice were divided into the Sham group (n=20), LPS group (n=20) and LPS + NEAT1 small interfering ribonucleic acid (siRNA) group (n=20). Sepsis-induced myocardial injury model in mice was established by intraperitoneal injection of LPS (10 mg/kg), and the NEAT1 knockout model was established by tail vein injection of NEAT1 siRNAs. After 12 h, the cardiac function of mice in each group was detected via the two-dimensional ultrasound; ejection fraction [EF (%)] and fraction shortening [FS (%)] were recorded. Hematoxylin and eosin (H&E) staining was conducted to evaluate the pathological changes in the heart tissues in each group. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was used to detect the apoptotic levels of myocardial cells and fibroblasts in each group. In addition, the expression level of the oxidative stress marker 4-hydroxynonena (4-HNE) and the positive proportions of cluster of differentiation 45 (CD45) and CD68 in the mouse heart of three groups were detected via immunohistochemical staining. Moreover, the messenger RNA (mRNA) expression levels of inflammatory indicators [interleukin-1 (IL-1), IL-6, monocyte chemotactic protein 1 (MCP-1) and tumor necrosis factor-alpha (TNF-α)] in mouse serum of the three groups were examined by enzyme-linked immunosorbent assay (ELISA). Finally, the effects of NEAT1 siRNAs on the Toll-like receptor 2 (TLR2)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway were detected by Western blotting. ENEAT1 knockdown could significantly improve ischemia/reperfusion (I/R)-induced cardiac insufficiency in rats, and increase EF (%) and FS (%) (p<0.05). Besides, NEAT1 knockdown remarkably inhibited the LPS-induced myocardial injury. Compared with the LPS group, LPS + NEAT 1 siRNA group has more orderly arranged cardiac myofilament, a lower degree of degradation and necrosis, and significantly reduced cell edema. TUNEL staining showed that NEAT1 knockdown markedly reduced LPS-induced apoptosis of cardiac cells (p<0.05). Immunohistochemical results revealed that NEAT1 knockdown could remarkably reverse LPS-induced elevation of the myocardial 4-HNE expression and decrease the oxidative stress in the heart (p<0.05). At the same time, CD45+ and CD68+ cells were reduced after NEAT1 knockdown in myocardial tissues (p<0.05). Reverse Transcription-Polymerase Chain Reaction (RT-PCR) showed that the mRNA levels of inflammatory indicators in LPS + NEAT1 siRNA group were lower than that in the LPS group (p<0.05). According to Western blotting results, NEAT1 siRNAs could significantly downregulate the protein expressions of TLR2 and p-p65. NEAT1 knockdown can improve LPS-induced myocardial injury in mice by inhibiting the TLR2/NF-κB signaling pathway. LncRNA NEAT1 is expected to be a potential target for clinical treatment of the sepsis-induced myocardial injury.

Circumferential strain rate to detect lipopolysaccharide-induced cardiac dysfunction: a speckle tracking echocardiography study.

Lipopolysaccharide (LPS)-induced myocardial dysfunction is a widely used indicator to study septic cardiomyopathy (SC). This study investigated the efficiency of strain rate imaging (SRI) in detecting LPS-induced myocardial dysfunction. A total of 30 mice were randomly assigned to saline group (n=10), 10 mg/kg LPS group (n=10) and 20 mg/kg LPS group (n=10). Then at baseline, 6 and 20 h after LPS injection, 2-D and M-mode echocardiography were conducted with GE Vivid 7 ultrasound (il3L linear probe, 10.0-14.0 MHz) and Echopac PC software. Ejection fraction (EF) and fractional shortening (FS) were measured with M-mode tracings. Serum biochemical examination was then performed to evaluate sepsis-induced myocardial injury. In LPS 20 mg/kg group, at 6 h after LPS injection, SRI found significantly decreased early diastolic strain rate (SRe, 1.76±1.05 vs. 3.18±0.83 unit/s, P<0.05), but M-mode echo found no change in EF and FS. In 10 mg/kg LPS group, compared with those at 6 h after LPS injection, SRI found a decline in SRe (1.57±0.75 vs. 3.18±0.83 unit/s, P<0.05), and M-mode tracings found an elevation in EF (71.31%±11.68% vs. 55.36%±7.42%, P<0.05) and FS (35.67%±8.79% vs. 25.43%±4.32%, P<0.05) at 20 h. Furthermore, LPS elevated the levels of serum creatine kinase-MB (CK-MB) and cardiac troponin-T (cTnT) at 20 h. SRI is useful to early assess LPS-induced cardiac deformation in mice. circumferential strain rate (SRcirc) is a sensitive indicator for LPS-induced myocardial injury in severe sepsis.

Inhibition of oxidative stress and autophagy by arbutin in lipopolysaccharide-induced myocardial injury

Background: Sepsis is a syndrome characterized by a systemic inflammatory response. Arbutin (Ar) is an active natural product known for its bactericidal and anti-inflammatory effects. Many studies have reported the diverse pharmacological actions of Ar, but there is no relevant research on the effect of Ar on lipopolysaccharide (LPS)-induced myocardial injury. Objective: The purpose of this study was to investigate the effect of Ar on LPS-induced myocardial injury and its underlying mechanisms. Materials and Methods: The levels of tumor necrosis factor alpha, interleukin 6, cardiac troponin-I, and procalcitonin were detected by ELISA. The levels of phosphorylated c-Jun N-terminal kinase (p-JNK), phosphorylated extracellular regulated protein kinase (p-ERK), and phosphorylated p38 (p-p38) proteins were detected by flow cytometry using Cytometric Bead Array. Western blot was used to detect the expression of autophagy-related and estrogen receptor (ER)-associated proteins. Levels of the oxidative stress-related markers were detected by the cuvette assay. Results: The levels of the inflammatory factors, LC3B, malondialdehyde, p-JNK, and p-p38 were increased in LPS-treated rats, while the ERK, total superoxide dismutase, glutathione peroxidase, p62, and ER-associated proteins were decreased. These effects could be effectively reversed by Ar, which could be blocked by ER antagonist ICI182780. Our previous study found Ar to possess an estrogen-like activity. Conclusion: Ar inhibits the oxidative stress and autophagy and offers protection from the LPS-induced myocardial injury via the ER pathway.

Sulfur dioxide attenuates sepsis-induced cardiac dysfunction via inhibition of NLRP3 inflammasome activation in rats

ObjectiveSulfur dioxide (SO2) plays an important role in maintaining homeostasis of cardiovascular system. This study was aimed to investigate cardioprotective effects of SO2 on in the rat and the underlying mechanism. Methods and resultsSepsis model induced by cecal ligation and puncture (CLP) in rats were used. SO2 donor (NaHSO3/Na2SO3, 1:3 M/M) was administered intraperitoneally at a dose of 85 mg/kg. Primary neonatal rat cardiac ventricular myocytes (NRCMs) were stimulated with LPS (1 mg/mL) in presence or absence of different concentrations of SO2 (10, 50 and 100 μmol/L). SO2 donor could restore the decreased levels of SO2 in plasma and heart of septic rats. SO2 exhibited dramatic improvement in cardiac functions. At 24 h after CLP, SO2 treatments decreased the number of TUNEL-positive cells, Bax/Bcl-2 ratio and activity of caspase-3. Moreover CLP-induced inflammatory response was also relieved by SO2. In NRCMs, SO2 could suppress the LPS-induced myocardial injury, leading to an increase in cell viability, a decrease in LDH and apoptotic rate. Western blot showed that the expression of TLR4, NLRP3, and Caspase-1 were obviously increased in myocardial tissue of CLP group or in NRCMs of LPS group, while SO2 significantly inhibited the CLP-induced or LPS-induced TLR4, NLRP3, and Caspase-1 expression. ConclusionSO2 attenuated sepsis-induced cardiac dysfunction likely in association with the inhibiting inflammation via TLR4/NLRP3 signaling pathway.