4-hydroxy-2-nonenal and Sepsis

Topics: Acute Kidney Injury; Aldehyde Dehydrogenase, Mitochondrial; Animals; Lipopolysaccharides; Mice; Oxidative Stress; Sepsis

Pyroptosis is a form of cell death triggered by the innate immune system that has been implicated in the pathogenesis of sepsis and acute lung injury. At the cellular level, pyroptosis is characterized by cell swelling, membrane rupture, and release of inflammatory cytokines, such as IL-1β. However, the role of endogenous lipids in pyroptosis remains underappreciated. We discovered that 4-hydroxynonenal (HNE), a major endogenous product of lipid peroxidation, inhibited pyroptosis and inflammasome activation. HNE at physiological concentrations (3 µM) blocked nigericin and ATP-induced cell death, as well as secretion of IL-1β, by mouse primary macrophages and human peripheral blood mononuclear cells. Treatment with HNE, or an increase of endogenous HNE by inhibiting glutathione peroxidase 4, reduced inflammasome activation in mouse models of acute lung injury and sepsis. Mechanistically, HNE inhibited the NLRP3 inflammasome activation independently of Nrf2 and NF-κB signaling, and had no effect on the NLRC4 or AIM2 inflammasome. Furthermore, HNE directly bound to NLRP3 and inhibited its interaction with NEK7. Our findings identify HNE as a novel, endogenous inhibitor of the NLRP3 inflammasome.

Topics: Acute Lung Injury; Aldehydes; Animals; Humans; Inflammasomes; Interleukin-1beta; Leukocytes, Mononuclear; Lipid Peroxidation; Macrophages; Mice; NLR Family, Pyrin Domain-Containing 3 Protein; Pyroptosis; Sepsis

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.

Topics: Aldehydes; Animals; Apoptosis; Biomarkers; Cardiomyopathies; Disease Models, Animal; Echocardiography; Gene Knockdown Techniques; Humans; Inflammation Mediators; Lipopolysaccharides; Male; Mice; Myocardium; Myocytes, Cardiac; NF-kappa B; Oxidative Stress; RNA, Long Noncoding; RNA, Small Interfering; Sepsis; Signal Transduction; Toll-Like Receptor 2

Sepsis is a leading cause of mortality among patients in intensive care units across the USA. Thioredoxin-1 (Trx-1) is an essential 12 kDa cytosolic protein that, apart from maintaining the cellular redox state, possesses multifunctional properties. In this study, we explored the possibility of controlling adverse myocardial depression by overexpression of Trx-1 in a mouse model of severe sepsis.. Adult C57BL/6J and Trx-1. Echocardiography analysis showed preserved cardiac function in the Trx-1. Our results indicate that overexpression of Trx-1 attenuates cardiac dysfunction during CLP. The mechanism of action may involve reduction of oxidative stress, apoptosis, and vascular permeability through activation of Trx-1/HO-1 and anti-apoptotic protein survivin.

Topics: Aldehydes; Animals; Apoptosis; Capillary Permeability; Cardiomyopathies; Carrier Proteins; Caspase 3; Disease Models, Animal; Echocardiography; Female; Heart; Heme Oxygenase-1; Immunohistochemistry; Inhibitor of Apoptosis Proteins; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myocardium; Oxidative Stress; Repressor Proteins; Sepsis; Survivin; Thioredoxins; Tyrosine

The aim of this study was to determine whether non-lethal sepsis induced by cecal ligation and puncture (CLP) modulates oxidative damage and enzymatic antioxidant defenses in diaphragm and hindlimb skeletal muscles (soleus and Extensor Digitorus Longus (EDL)).. Female Wistar rats were divided into four experimental groups: (1) control animals, (2) animals sacrificed 2 hours or (3) 7 days after CLP, and (4) sham-operated animals. At the end of the experimental procedure, EDL, soleus, and diaphragm muscles were harvested and 4-hydroxynonenal (HNE)-protein adducts and protein carbonyl contents were examined in relation to superoxide dismutase and catalase expression and activities.. We observed that both non-respiratory oxidative (i.e. soleus) and glycolytic skeletal muscles (i.e. EDL) are more susceptible to sepsis-induced oxidative stress than diaphragm, as attested by an increase in 4-HNE protein adducts and carbonylated proteins after 2 hours of CLP only in soleus and EDL.. These differences could be explained by higher basal enzymatic antioxidant activities in diaphragm compared to hindlimb skeletal muscles. Together, these results demonstrate that diaphragm is better protected from oxidative stress than hindlimb skeletal muscles during CLP-induced sepsis.

Topics: Aldehydes; Animals; Antioxidants; Catalase; Cecum; Diaphragm; Female; Hindlimb; Ligation; Muscle, Skeletal; Oxidative Stress; Protein Carbonylation; Rats, Wistar; Sepsis; Superoxide Dismutase

Oxidative stress and inflammation contribute to the diaphragm contractile dysfunction observed in animal models of sepsis and endotoxemia. In septic patients, molecular events have never been explored in their respiratory muscles. Levels of oxidative stress and inflammation were evaluated in a respiratory muscle, the external intercostal, and a limb muscle, the vastus lateralis, of patients with sepsis.. Levels of oxidized and nitrated proteins, protein adducts of malondialdehyde and hydroxinonenal, antioxidant enzymes catalase and Mn-superoxide dismutase, tumor necrosis factor (TNF)-α, TNF-α receptors i and ii, interleukin (IL)-1 and IL-6, the panleukocyte marker CD18, and fiber type composition were explored using immunoblotting, real time-polymerase chain reaction, and immunohistochemistry in the external intercostal and vastus lateralis of patients with severe sepsis and/or septic shock.. Compared to the controls, in septic patients, levels of oxidized and nitrated proteins were increased in the vastus lateralis, but not in the external intercostal, while those of the antioxidant enzymes did not differ, and the proportions and sizes of the muscle fibers were not significantly different in any muscle between patients and controls.. Differences in activity between the respiratory and limb muscles may account for the differential pattern of oxidative stress and inflammation observed among patients with severe sepsis. These findings may have relevant implications for the clinical and therapeutic management of these patients.

Topics: Adult; Aged; Aged, 80 and over; Aldehydes; Biomarkers; Catalase; Cross-Sectional Studies; Cytokines; Female; Humans; Inflammation; Intercostal Muscles; Male; Malondialdehyde; Middle Aged; Muscle Fibers, Skeletal; Muscle Proteins; Nitrogen; Oxidation-Reduction; Oxidative Stress; Quadriceps Muscle; Sepsis; Shock, Septic; Superoxide Dismutase

This study describes increased sarcolemmal permeability and myofilamentar damage that occur together with lipid peroxidation and protein nitration in the myocardium in severe sepsis induced by cecal ligation and puncture. Male C57BL/6 mice were submitted to moderate and severe septic injury and sham operation. Using light and laser confocal microscopy, diffuse foci of myocytolysis associated with focal disruption of the actin/myosin contractile apparatus could be seen in hearts with severe septic injury. The myocardial expressions of the sarcomeric proteins myosin and actin were downregulated by both severe and moderate injuries. The detection of albumin staining in the cytoplasm of myocytes to evaluate sarcolemmal permeability provided evidence of severe and mild injury of the plasma membrane in hearts with severe and moderate septic injury, respectively. The administration of a superoxide scavenger caused marked reduction of sarcolemmal permeability, indicating the involvement of free radicals in its genesis. On electron microscopy, these changes were seen to correspond to spread blocks of a few myocytes with fragmentation and dissolution of myofibrils, intracellular edema, and, occasionally, rupture of the sarcolemma. In addition, oxidative damage to lipids, using anti-4-hydroxynonenal, an indicator of oxidative stress and disruption of plasma membrane lipids, and to proteins, using antinitrotyrosine, a stable biomarker of peroxynitrite-mediated protein nitration, was demonstrated. These findings make plausible the hypothesis that increased sarcolemmal permeability might be a primary event in myocardial injury in severe sepsis possibly due to oxidative damage to lipids and proteins that could precede phenotypic changes that characterize a septic cardiomyopathy.

Topics: Actins; Aldehydes; Animals; Cardiomyopathies; Cecum; Down-Regulation; Ligation; Lipid Peroxidation; Male; Mice; Mice, Inbred C57BL; Models, Animal; Myocardium; Myosins; Permeability; Proteins; Punctures; Sarcolemma; Sepsis

Although 4-hydroxy-2-nonenal (HNE, a product of lipid peroxidation) is a major cause of oxidative damage inside skeletal muscles, the exact proteins modified by HNE are unknown. We used two-dimensional electrophoresis, immunoblotting, and mass spectrometry to identify selective proteins targeted by HNE inside the diaphragm of rats under two conditions: severe sepsis [induced by E. coli lipopolysaccharides (LPS)] and during strenuous muscle contractions elicited by severe inspiratory resistive loading (IRL). Diaphragm HNE-protein adduct formation (detected with a polyclonal antibody) increased significantly after 1 and 3 h of LPS injection with a return to baseline values thereafter. Similarly, HNE-protein adduct formation inside the diaphragm rose significantly after 6 but not 3 h of IRL. Mass spectrometry analysis of HNE-modified proteins revealed enolase 3b, aldolase and triosephosphate isomerase 1, creatine kinase, carbonic anyhdrase III, aconitase 2, dihydrolipoamide dehydrogenase, and electron transfer flavoprotein-beta. Measurements of in vitro enolase activity in the presence of pure HNE revealed that HNE significantly attenuated enolase activity in a dose-dependent fashion, suggesting that HNE-derived modifications have inhibitory effects on enzyme activity. We conclude that lipid peroxidation products may inhibit muscle contractile performance through selective targeting of enzymes involved in glycolysis, energy production as well as CO(2) hydration.

Topics: Aldehydes; Animals; Disease Models, Animal; Electrophoresis, Gel, Two-Dimensional; Enzymes; Escherichia coli; Growth Inhibitors; Lipid Peroxidation; Lipopolysaccharides; Male; Rats; Rats, Sprague-Dawley; Respiratory Muscles; Sepsis

UCP3 has been postulated to function in the defense against lipid-induced oxidative muscle damage (lipotoxicity). We explored this hypothesis during cachexia in rats (zymosan-induced sepsis), a condition characterized by increased oxidative stress and supply of fatty acids to the muscle. Muscle UCP3 protein content was increased 2, 6 and 11 days after zymosan injection. Plasma FFA levels were increased at day 2, but dropped below control levels on days 6 and 11. Muscular levels of the lipid peroxidation byproduct 4-hydroxy-2-nonenal (4-HNE) were increased at days 6 and 11 in zymosan-treated rats, supporting a role for UCP3 in modulating lipotoxicity during cachexia.

Topics: Aldehydes; Animals; Cachexia; Disease Models, Animal; Humans; Ion Channels; Lipid Peroxidation; Male; Mitochondrial Proteins; Muscle, Skeletal; Muscular Atrophy; Oxidation-Reduction; Oxidative Stress; Protein Biosynthesis; Rats; Rats, Wistar; Sepsis; Uncoupling Protein 3; Wasting Syndrome; Zymosan

We investigated the role of oxidative stress in the pathogenesis of septic ileus. Sepsis was induced by intraperitoneal (i.p.) injection of lipopolysaccharides (LPS, 20 mg kg(-1)) in mice. The effect of two i.p. injections of superoxide dismutase [polyethylene glycol (PEG)-SOD, 4000 U kg(-1)] and catalase (PEG-CAT, 15,000 U kg(-1)) was investigated on gastric emptying, intestinal transit and total nitrite plasma concentrations. We also performed immunohistochemical experiments on gastric and ileal tissue. LPS significantly delayed gastric emptying and intestinal transit while plasma nitrite levels increased. Polyethylene glycol (PEG)-SOD reversed the endotoxin-induced delay in gastric emptying and improved the delay in intestinal transit without effect on plasma nitrite levels. PEG-CAT slightly improved the delay in gastric emptying without effect on intestinal transit. Immunohistochemistry showed the presence of nitrotyrosine (NT) and 4-hydroxy-2-nonenal (HNE) in the gastric and ileal mucosa of LPS-treated mice. Treatment with PEG-SOD or PEG-CAT of LPS mice diminished the presence of NT or HNE in both tissues. In addition, LPS induced a significant increase in inducible nitric oxide synthase (iNOS)-positive residential macrophages in the external musculature of stomach and ileum, which significantly decreased after PEG-SOD or PEG-CAT treatment. The present results support a role for oxidative and nitrosative stress in the pathogenesis of septic ileus in mice.

Topics: Aldehydes; Animals; Antioxidants; Catalase; Disease Models, Animal; Gastric Emptying; Gastrointestinal Transit; Ileus; Immunohistochemistry; Intestinal Mucosa; Lipopolysaccharides; Macrophages; Male; Mice; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; Oxidative Stress; Sepsis; Superoxide Dismutase; Tyrosine

Immunohistochemical analysis of the distribution of the lipid peroxidation product 4-hydroxynonenal (HNE) in the brain of baboons exposed to experimental hemorrhagic traumatic shock or sepsis showed that systemic oxidative stress and the thereby generated HNE affect the blood:brain barrier and the regulation of cerebral blood flow determining secondary brain damage. Similarly, HNE was determined during ischemia in the brain blood vessels of rats exposed to ischemia/reperfusion injury of the brain. After reperfusion, HNE disappeared from the blood vessels but remained in neurones and in glial cells. Since HNE modulates cell proliferation and differentiation (including proto-oncogene expression), it is postulated that HNE might have prominent local and systemic effects that are not only harmful but beneficial, too, determining the outcome of various pathophysiological conditions based on oxidative stress.

Topics: Aldehydes; Animals; Antibodies, Monoclonal; Brain; Cell Division; Cerebral Hemorrhage; Free Radicals; HeLa Cells; Humans; Immunohistochemistry; Ischemic Attack, Transient; Muscle, Smooth, Vascular; Papio; Proto-Oncogene Mas; Proto-Oncogene Proteins c-fos; Rats; Rats, Wistar; Second Messenger Systems; Sepsis; Shock; Thymidine