Antioxidant treatment reverses mitochondrial dysfunction in a sepsis animal model

Beneficial impact of cardiac heavy metal scavenger metallothionein in sepsis-provoked cardiac anomalies dependent upon regulation of endoplasmic reticulum stress and ferroptosis but not autophagy

AIMS

Sepsis represents a profound proinflammatory response with a major contribution from oxidative injury. Here we evaluated possible impact of heavy metal scavenger metallothionein (MT) on endotoxin lipopolysaccharide (LPS)-induced oxidative stress, endoplasmic reticulum (ER) stress, autophagy, and ferroptosis enroute to myocardial injury along with interplay among these stress domains.

MATERIALS AND METHODS

Echocardiographic, cardiomyocyte mechanical and intracellular Ca2+ responses were monitored in myocardia from WT and transgenic mice with cardiac-selective MT overexpression challenged with LPS. Oxidative stress, stress signaling (p38, ERK, JNK), ER stress, autophagy, and ferroptosis were scrutinized.

KEY FINDINGS

RNAseq analysis revealed discrepant patterns in ferroptosis between LPS-exposed and normal murine hearts. LPS insult enlarged LV end systolic dimension, suppressed fractional shortening, ejection fraction, maximal velocity of shortening/relengthening and peak shortening, as well as elongated relengthening along with dampened intracellular Ca2+ release and reuptake. In addition, LPS triggered oxidative stress (lowered glutathione/glutathione disulfide ratio and O2- production), activation of stress cascades (p38, ERK, JNK), ER stress (GRP78, PERK, Gadd153, and IRE1α), inflammation (TNFα and iNOS), unchecked autophagy (LCB3, Beclin-1 and Atg7), ferroptosis (GPx4 and SLC7A11) and interstitial fibrosis. Although MT overexpression itself did not reveal response on cardiac function, it attenuated or mitigated LPS-evoked alterations in echocardiographic, cardiomyocyte contractile and intracellular Ca2+ characteristics, O2- production, TNFα level, ER stress and ferroptosis (without affecting autophagy, elevated AMP/ATP ratio, and iNOS). In vitro evidence revealed beneficial effects of suppression of oxidative stress, ER stress and ferroptosis against LPS-elicited myocardial anomalies.

SIGNIFICANCE

These data strongly support the therapeutic promises of MT and ferroptosis in septic cardiomyopathy.

Mitochondrial Sirt3 serves as a biomarker for sepsis diagnosis and mortality prediction

The purpose of this study is to determine whether the levels of serum Sirt3 correlate with disease severity and perfusion indicators in septic patients, as well as to assess the clinical value of Sirt3 as a potential novel marker for sepsis diagnosis and mortality prediction. A total of 79 patients in the ICU were included in the study, of which 28 were postoperatively noninfectious and the remaining 51 patients were all diagnosed with sepsis during the study period. The levels of Sirt3 were detected and dynamically monitored by enzyme-linked adsorption method, Pearson or Spearman coefficient for correlation analysis between Sirt3 and clinical indicators, ROC curve for evaluation of diagnosis and mortality prediction, Kaplan-Meier method for the significance of Sirt3 in 28-day survival. The serum levels of Sirt3 were lower in the sepsis patients on day 1 (P < 0.0001), and the septic shock group had lower Sirt3 levels than the sepsis group (P = 0.013). Sirt3 had good negative correlations with SOFA scores both in sepsis and septic shock groups (Pearson: r² = - 0.424, - 0.518; P = 0.011, 0.040), and Sirt3 correlated strongly with ScvO₂ in the septic shock group (Pearson: r² = - 0.679, P = 0.004) and with PCT in the sepsis group (Pearson: r² = - 0.409, P = 0.015). Sirt3 not only performed well in identifying sepsis (AUC = 0.995, 95% CI 0.987-1, P < 0.0001) but also greatly enhanced lactate's specificity in detecting septic shock (from 91.43 to 94.29%). Patients in the low Sirt3 group had higher ScvO₂, lactate, APACHE II score, SOFA score, longer ICU stays, and worse indicators of inflammation (TNF-α, IL-6) and infection (PCT) than those in the high Sirt3 group (P < 0.05). Additionally, Sirt3 can predict mortality of sepsis (AUC = 0.746, 95% CI 0.571-0.921, P = 0.022), patients with serum Sirt3 < 10.07 pg/ml have a lower 28-day survival (log-rank P = 0.008). Low serum levels of Sirt3 are significantly correlated with the disease severity. At the same time, Sirt3 increases the sensitivity of lactate to detect "cellular hypoxia" in septic shock. Sirt3 is a promising biomarker for the diagnosis of sepsis and predicting mortality risk in septic patients.

Association of Metformin Use During Hospitalization and Mortality in Critically Ill Adults With Type 2 Diabetes Mellitus and Sepsis

OBJECTIVES

Whether metformin exposure is associated with improved outcomes in patients with type 2 diabetes mellitus and sepsis.

DESIGN

Retrospective cohort study.

SETTING

Patients admitted to ICUs in 16 hospitals in Pennsylvania from October 2008 to December 2014.

PATIENTS

Adult critical ill patients with type 2 diabetes mellitus and sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We conducted a retrospective cohort study to compare 90-day mortality in diabetic patients with sepsis with and without exposure to metformin during hospitalization. Data were obtained from the electronic health record of a large healthcare system in Pennsylvania from October 2008 to December 2014, on patients admitted to the ICU at any of the 16 hospitals within the system. The primary outcome was mortality at 90 days. The absolute and adjusted odds ratio (OR) with 95% CI were calculated in a propensity score-matched cohort. Among 14,847 patients with type 2 diabetes mellitus and sepsis, 682 patients (4.6%) were exposed to metformin during hospitalization and 14,165 (95.4%) were not. Within a total of 2,691 patients subjected to propensity score-matching at a 1:4 ratio, exposure to metformin (n = 599) was associated with decreased 90-day mortality (71/599, 11.9% vs 475/2,092, 22.7%; OR, 0.46; 95% CI, 0.35-0.60), reduced severe acute kidney injury (50% vs 57%; OR, 0.75; 95% CI, 0.62-0.90), less Major Adverse Kidney Events at 1 year (OR, 0.27; 95% CI, 0.22-0.68), and increased renal recovery (95% vs 86%; OR, 6.43; 95% CI, 3.42-12.1).

CONCLUSIONS

Metformin exposure during hospitalization is associated with a decrease in 90-day mortality in patients with type 2 diabetes mellitus and sepsis.

Regulation of Oxidative Phosphorylation of Liver Mitochondria in Sepsis

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

In vivo evaluation of the protective effects of arjunolic acid against lipopolysaccharide-induced septic myocardial injury

Lipopolysaccharide (LPS) is a glycolipid component of the cell wall of Gram-negative bacteria, which induces multiple organ dysfunctions, eventually leading to septic shock and death. Arjunolic acid (AA) has been shown to have therapeutic benefits against various organ pathophysiologies, although its role in sepsis remains unclear. Here, we evaluated the effects of AA on LPS-induced free radical production and cardiotoxicity. Male albino mice were allocated to four groups: normal, 1.5 µg/30 g b.w. of LPS (LPS), 20 mg/kg b.w. AA with LPS (AA+LPS) and 20 mg/kg b.w. of AA (AA). Subsequently, blood and heart samples were harvested for biochemical and histopathological examinations. Pretreatment with AA attenuated LPS-induced increased serum levels of cardiac troponin I, lactate dehydrogenase and creatine kinase. In the meantime, AA pretreatment before LPS resulted in a significant increase in endogenous antioxidants (superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione) and a significant decrease in the level of lipid peroxidation product (malondialdehyde) in the heart as compared to the LPS group, while cardiac cytochrome c activity were significantly increased. In addition, in the AA-pretreated mice, C-reactive protein and proinflammatory cytokines (interlukin-1 and tumor necrosis factor-alpha) were significantly reduced, and anti-inflammatory cytokines (interleukin-4 and -10) were significantly increased in cardiac tissues as compared to the LPS-treated animals. Furthermore, prior administration of AA to LPS exposed mice led to a significant a significant decrease in heart caspase-3, -8, and -9 as compared to the LPS group. Interestingly, AA was also able to improve LPS-induced histopathological changes in the cardiomyocytes. In conclusion, these in vivo findings indicate that AA may be a promising cardioprotective agent against LPS-stimulated cardiotoxicity, at least in part, through upregulation of cardiac antioxidants, reduction of lipid peroxidation, and inhibition of inflammation and cardiac cell death.

Role of Creatine Supplementation in Conditions Involving Mitochondrial Dysfunction: A Narrative Review

Creatine monohydrate (CrM) is one of the most widely used nutritional supplements among active individuals and athletes to improve high-intensity exercise performance and training adaptations. However, research suggests that CrM supplementation may also serve as a therapeutic tool in the management of some chronic and traumatic diseases. Creatine supplementation has been reported to improve high-energy phosphate availability as well as have antioxidative, neuroprotective, anti-lactatic, and calcium-homoeostatic effects. These characteristics may have a direct impact on mitochondrion's survival and health particularly during stressful conditions such as ischemia and injury. This narrative review discusses current scientific evidence for use or supplemental CrM as a therapeutic agent during conditions associated with mitochondrial dysfunction. Based on this analysis, it appears that CrM supplementation may have a role in improving cellular bioenergetics in several mitochondrial dysfunction-related diseases, ischemic conditions, and injury pathology and thereby could provide therapeutic benefit in the management of these conditions. However, larger clinical trials are needed to explore these potential therapeutic applications before definitive conclusions can be drawn.

Electroacupuncture Relieves Hippocampal Injury by Heme Oxygenase-1 to Improve Mitochondrial Function

INTRODUCTION

Electroacupuncture (EA) treatment has been demonstrated to have the potential to prevent sepsis-induced hippocampal injury; however, the mechanisms underlying the protective effects of EA against such injury remain unclear. Herein, to elucidate these mechanisms, we constructed a mouse model of lipopolysaccharide (LPS)-induced hippocampal injury to investigate the protection mechanism of EA and to determine whether heme oxygenase-1 (HO-1)-mediated mitochondrial function is involved in the protective effect of EA.

MATERIALS AND METHODS

The sepsis model of hippocampal injury was induced by administering LPS. The Zusanli and Baihui acupoints were stimulated using EA for 30 min once a day, for 5 d before LPS exposure and the first day after administering LPS. Hippocampal injury was investigated by hematoxylin and eosin staining and Nissl staining. HO-1 levels were measured using Western blotting. Mitochondrial metabolism was validated by assessing adenosine triphosphate, superoxide dismutase, malondialdehyde levels, reactive oxygen species production, and mitochondrial respiratory chain activity. Mitochondrial morphology was analyzed by transmission electron microscopy.

RESULTS

EA treatment alleviated neuronal injury, impeded oxidative stress, and improved mitochondrial respiratory function, energy metabolism, and mitochondrial morphology in LPS-exposed mice. In addition, HO-1 knockout aggravated LPS-induced hippocampal injury, aggravated oxidative stress, and reduced mitochondrial respiratory function and aggravated mitochondrial swelling, crest relaxation, and vacuole degeneration. Moreover, EA was unable to reverse the hippocampal damage and mitochondrial dysfunction caused by LPS exposure after HO-1 knockout.

CONCLUSIONS

EA improves LPS-induced hippocampal injury by regulating HO-1-mediated mitochondrial function. Furthermore, HO-1 plays a critical role in maintaining mitochondrial function and resisting oxidative injury.

Sirtuins and Sepsis: Cross Talk between Redox and Epigenetic Pathways

Sepsis and septic shock are the leading causes of death among hospitalized patients in the US. The immune response in sepsis transitions from a pro-inflammatory and pro-oxidant hyper-inflammation to an anti-inflammatory and cytoprotective hypo-inflammatory phase. While 1/3rd sepsis-related deaths occur during hyper-, a vast majority of sepsis-mortality occurs during the hypo-inflammation. Hyper-inflammation is cytotoxic for the immune cells and cannot be sustained. As a compensatory mechanism, the immune cells transition from cytotoxic hyper-inflammation to a cytoprotective hypo-inflammation with anti-inflammatory/immunosuppressive phase. However, the hypo-inflammation is associated with an inability to clear invading pathogens, leaving the host susceptible to secondary infections. Thus, the maladaptive immune response leads to a marked departure from homeostasis during sepsis-phases. The transition from hyper- to hypo-inflammation occurs via epigenetic programming. Sirtuins, a highly conserved family of histone deacetylators and guardians of homeostasis, are integral to the epigenetic programming in sepsis. Through their anti-inflammatory and anti-oxidant properties, the sirtuins modulate the immune response in sepsis. We review the role of sirtuins in orchestrating the interplay between the oxidative stress and epigenetic programming during sepsis.

Anti-Inflammatory Mechanisms of Novel Synthetic Ruthenium Compounds

Inflammation is the primary biological reaction to induce severe infection or injury in the immune system. Control of different inflammatory cytokines, such as nitric oxide (NO), interleukins (IL), tumor necrosis factor alpha-(TNF-α), noncytokine mediator, prostaglandin E2 (PGE2), mitogen activated protein kinases (MAPKs) and nuclear factor kappa B (NF-κB), facilitates anti-inflammatory effect of different substances. Coordination metal complexes have been applied as metallo-drugs. Several metal complexes have found to possess potent biological activities, especially anticancer, cardioprotective, chondroprotective and anti-parasitosis activities. Among the metallo drugs, ruthenium-based (Ru) complexes have paid much attention in clinical applications. Despite the kinetic nature of Ru complexes is similar to platinum in terms of cell division events, their toxic effect is lower than that of cisplatin. This paper reviews the anti-inflammatory effect of novel synthetic Ru complexes with potential molecular mechanisms that are actively involved.

6-Shogaol Mitigates Sepsis-Associated Hepatic Injury through Transcriptional Regulation

Sepsis-associated liver dysfunction presents a significant public health problem. 6-Shogaol is the key bioactive component in dry ginger, which has antioxidant and anti-inflammation capacity. The present study aims to investigate the preventive effect of 6-shogaol on sepsis-induced liver injury. 6-Shogaol was administered to mice for 7 consecutive days before being intraperitoneally injected with lipopolysaccharide (LPS). After 24 h, mice were sacrificed, and biochemical and transcriptomic analyses were performed. Our results demonstrated that 6-shogaol prevented LPS-induced impairment in antioxidant enzymes and elevation in malondialdehyde level in the liver. The hepatic inflammatory response was significantly suppressed by 6-shogaol through suppressing the MAPK/NFκB pathway. RNA-sequencing data analysis revealed that 41 overlapped genes between the LPS vs. control group and 6-shogaol vs. LPS group were identified, among which 36 genes were upregulated, and 5 genes were downregulated for the LPS vs. control group. These overlapped genes are enriched in inflammation-related pathways, e.g., TNF and NFκB. The mRNA expression of the overlapped genes was also verified in the LPS-induced BRL-3A cell model. In summary, 6-shogaol shows great potential as a natural chemopreventive agent to treat sepsis-associated hepatic disorders.

Columbianadin Dampens In Vitro Inflammatory Actions and Inhibits Liver Injury via Inhibition of NF-κB/MAPKs: Impacts on ∙OH Radicals and HO-1 Expression

Columbianadin (CBN), a natural coumarin isolated from Angelica decursiva, is reported to have numerous biological activities, including anticancer and platelet aggregation inhibiting properties. Here, we investigated CBN’s anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated RAW 264.7 cell activation and deciphered the signaling process, which could be targeted by CBN as part of the mechanisms. Using a mouse model of LPS-induced acute liver inflammation, the CBN effects were examined by distinct histologic methods using trichrome, reticulin, and Weigert’s resorcin fuchsin staining. The result showed that CBN decreased LPS-induced expressions of TNF-α, IL-1β, and iNOS and NO production in RAW 264.7 cells and mouse liver. CBN inhibited LPS-induced ERK and JNK phosphorylation, increased IκBα levels, and inhibited NF-κB p65 phosphorylation and its nuclear translocation. Application of inhibitors for ERK (PD98059) and JNK (SP600125) abolished the LPS-induced effect on NF-κB p65 phosphorylation, which indicated that ERK and JNK signaling pathways were involved in CBN-mediated inhibition of NF-κB activation. Treatment with CBN decreased hydroxyl radical (^•OH) generation and increased HO-1 expression in RAW 264.7 cells. Furthermore, LPS-induced liver injury, as indicated by elevated serum levels of liver marker enzymes (aspartate aminotransferase (AST) and alanine aminotransferase (ALT)) and histopathological alterations, were reversed by CBN. This work demonstrates the utility of CBN against LPS-induced inflammation, liver injury, and oxidative stress by targeting JNK/ERK and NF-κB signaling pathways.

Protective effects of ginsenoside-Rg2 and -Rh1 on liver function through inhibiting TAK1 and STAT3-mediated inflammatory activity and Nrf2/ARE-mediated antioxidant signaling pathway

Systemic or hepatic inflammation is caused by intraperitoneal application of lipopolysaccharide (LPS). In this study, we investigated anti-inflammatory and antioxidant properties of combination of ginsenoside-Rg2 (G-Rg2) and -Rh1 (G-Rh1) on liver function under LPS challenging. We first confirmed that G-Rg2 and -Rh1 at 100 μg/ml did not show cytotoxicity in HepG2 cells. G-Rg2 and -Rh1 treatment significantly inhibited activation of STAT3 and TAK1, and inflammatory factors including iNOS, TNF-α, and IL-1β in peritoneal macrophages. In HepG2 cells, G-Rg2 and -Rh1 treatment inhibited activation of STAT3 and TAK1/c-Jun N-terminal kinase, and down-regulated nuclear translocation of NF-κB transcription factor. In addition, LPS-induced mitochondrial dysfunction was restored by treatment with G-Rg2 and -Rh1. Interestingly, pretreatment with G-Rg2 and -Rh1 effectively inhibited mitochondrial damage-mediated ROS production induced by LPS stimulation, and alterations of Nrf2 nuclear translocation and ARE promotor activity were involved in G-Rg2 and -Rh1 effects on balancing ROS levels. In liver tissues of LPS-treated mice, G-Rg2 and -Rh1 treatment protected liver damages and increased Nrf2 expression while reducing CD45 expression. Taken together, G-Rg2 and -Rh1 exerts a protective effect on liver function by increasing antioxidant through Nrf2 and anti-inflammatory activities through STAT3/TAK1 and NF-κB signaling pathways in liver cells and macrophages.

Effects of Moringa oleifera Leaf Extract on Diabetes-Induced Alterations in Paraoxonase 1 and Catalase in Rats Analyzed through Progress Kinetic and Blind Docking

In our study, we aimed to evaluate the effects of Moringa oleifera leaves extract on rat paraoxonase 1 (rPON1) and catalase (rCAT) activities in alloxan-induced diabetic rats. Our study included three groups; group C (control, n = 5); group D (diabetic, n = 5); and group DM (M. oleifera extract-supplemented diabetic rats, n = 5). Daily oral administration of M. oleifera extract at 200 mg/kg doses produced an increase in endogenous antioxidants. Serum rPON1 (lactonase) and liver cytosol catalase activities were determined by a spectrophotometric assay using progress curve analysis. We found a decrease in the Vm value of rPON1 in diabetic rats, but dihydrocoumarin (DHC) affinity (Km) was slightly increased. The value of Vm for the DM group was found to be reduced approximately by a factor of 3 compared with those obtained for group C, whereas Km was largely changed (96 times). Catalase activity was significantly higher in the DM group. These data suggest that the activation of rPON1 and rCAT activities by M. oleifera extracts may be mediated via the effect of the specific flavonoids on the enzyme structure. In addition, through molecular blind docking analysis, rPON1 was found to have two binding sites for flavonoids. In contrast, flavonoids bound at four sites in rCAT. In conclusion, the data suggest that compounds from M. oleifera leaves extract were able to influence the catalytic activities of both enzymes to compensate for the changes provoked by diabetes in rats.

Oleuropein protects against lipopolysaccharide-induced sepsis and alleviates inflammatory responses in mice

Sepsis results from a major systemic inflammatory response and can induce disorders in multiple organs. The present study evaluated the potential protective effects of oleuropein (OLE) against hyperinflammatory responses during lipopolysaccharide (LPS)-induced sepsis in mice. Sixty male Balb/c mice were randomly categorized into five groups of 12 animals each: control, intraperitoneally injected with OLE (50 mg/kg), injected with LPS (10 mg/kg, intraperitoneal), and two groups administered OLE (25 and 50 mg/kg) for 3 days prior to LPS injection. Twenty-four hours after lipopolysaccharide injection, the animals were sacrificed. Serum, liver, and kidney tissue samples were collected for biochemical analyses, histopathological examinations, and investigation of inflammation-related gene expression. OLE pretreatment significantly reduced liver damage parameters (alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase) and kidney damage parameters (blood urea nitrogen, creatinine, and kidney injury molecule-1) in the septic mice. OLE pretreatment ameliorated LPS-induced liver and kidney histological changes. OLE significantly mitigated the increased levels of malondialdehyde in the liver and kidneys and reduced levels of reduced glutathione induced by LPS. LPS injection also resulted in increased expression of the proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and inflammation-related genes (Nos2, Hmgb1, Mpo, Cd46, Map2k4, and Map2k7) in the hepatic and renal tissues. OLE reduced these expressions to ameliorate the inflammatory response. Moreover, OLE pretreatment enhanced the survival rate of septic mice. In conclusion, OLE alleviated the inflammatory response to protect against LPS-induced sepsis in mice.

Inhibition of miR-103a-3p suppresses lipopolysaccharide-induced sepsis and liver injury by regulating FBXW7 expression

Inflammation, apoptosis, and oxidative stress are involved in septic liver dysfunction. Herein, the role of miR‐103a‐3p/FBXW7 axis in lipopolysaccharides (LPS)‐induced septic liver injury was investigated in mice. Hematoxylin‐eosin staining was used to evaluate LPS‐induced liver injury. Quantitative real‐time polymerase chain reaction was performed to determine the expression of microRNA (miR) and messenger RNA, and western blot analysis was conducted to examine the protein levels. Dual‐luciferase reporter assay was used to confirm the binding between miR‐103a‐3p and FBXW7. Both annexin V‐fluoresceine isothiocyanate/propidium iodide staining and caspase‐3 activity were employed to determine cell apoptosis. First, miR‐103a‐3p was upregulated in the septic serum of mice and patients with sepsis, and miR‐103a‐3p was elevated in the septic liver of LPS‐induced mice. Then, interfering miR‐103a‐3p significantly decreased apoptosis by suppressing Bax expression and upregulating Bcl‐2 levels in LPS‐induced AML12 and LO2 cells, and septic liver of mice. Furthermore, inhibition of miR‐103a‐3p repressed LPS‐induced inflammation by downregulating the expression of tumor necrosis factor, interleukin 1β, and interleukin 6 in vitro and in vivo. Meanwhile, interfering miR‐103a‐3p obviously attenuated LPS‐induced overactivation of oxidation via promoting expression of antioxidative enzymes, including catalase, superoxide dismutase, and glutathione in vitro and in vivo. Moreover, FBXW7 was a target of miR‐103a‐3p, and overexpression of FBXW7 significantly ameliorated LPS‐induced septic liver injury in mice. Finally, knockdown of FBXW7 markedly reversed anti‐miR‐103a‐3p‐mediated suppression of septic liver injury in mice. In conclusion, interfering miR‐103a‐3p or overexpression of FBXW7 improved LPS‐induced septic liver injury by suppressing apoptosis, inflammation, and oxidative reaction.

Activation of Alpha-7 Nicotinic Acetylcholine Receptors (α7nAchR) Promotes the Protective Autophagy in LPS-Induced Acute Lung Injury (ALI) In Vitro and In Vivo

The release of inflammatory cytokines and chemokines and autophagy has been reported to be involved in the pathogenic mechanism of acute lung injury (ALI). Reportedly, alpha-7 nicotinic acetylcholine receptors (α7nAchR) might play a protective role in LPS-induced ALI. In the current research, we established LPS-induced ALI model in mice and α7nAchR agonist PNU-282987 improved LPS-induced injury. In MH-S cells, LPS stimulation inhibited, whereas α7nAchR agonist PNU-282987 enhanced the autophagy. α7nAchR agonist PNU-282987 protected MH-S cells from LPS-induced inflammation by reducing the concentrations of IL-6, TNF-α, and IL-1β. Finally, LPS stimulation dramatically inhibited MH-S cell viability but enhanced cell apoptosis, whereas PNU-282987 treatment exerted opposite effects; α7nAchR might regulate the cellular homeostasis via affecting the crosstalk between the autophagy and apoptosis in MH-S cells; in other words, α7nAChR agonist enhances MH-S cell autophagy and inhibits MH-S cell apoptosis. In conclusion, α7nAchR promote the protective autophagy in LPS-induced ALI model in mice and MH-S cells. The application of α7nAchR agonist is considered a potent target for LPS-induced ALI, which needs further clinical investigation.

Hypothermia Effects on Liver and Kidney Oxidative Stress Parameters in an Experimental Model of Sepsis in Rats

INTRODUCTION

Oxidative stress (OS) seems to be an important mediator of cellular injury, from which sepsis can proceed. Studies have demonstrated the protective effect of controlled hypothermia in sepsis. This study aimed to evaluate its effects on OS parameters in rat hepatic and renal tissue septic after caecal ligation and puncture (CLP).

MATERIAL AND METHODS

Three groups were appointed (10 rats/group): C (control), SN (sepsis normothermic), and SH (sepsis hypothermic). Ten hours from CLP, the liver and kidneys were harvested and total protein concentration, superoxide dismutase (SOD), glutathione peroxidase (GPx) activities, lipid peroxidation level (malondialdehyde (MDA), carbonylated proteins (2,4-dinitrophenylhydrazine (DNPH), and fatty acid profile were analysed.

RESULTS

Sepsis significantly increased SOD and GPx activities in the liver, regardless of the temperature. In renal tissue, GPx activity increased significantly in normothermic conditions and SOD tended to decrease in hypothermic conditions. MDA and DNPH concentrations increase in both tissues after CLP. Hypothermia significantly lowered MDA in the liver but only changed it insignificantly in the kidneys. The DNPH in the liver and kidneys was significantly lower in hypothermic conditions. The unsaturated-to-saturated fatty acids ratio was significantly lower in sepsis, and the fall in temperature raised this ratio.

CONCLUSION

Experimentally induced sepsis in rats enhances OS in the liver and kidneys. The effect of hypothermia on OS indices is dependent on the type of tissue.

Mitochondria and Critical Illness

Classically, mitochondria have largely been believed to influence the development of illness by modulating cell metabolism and determining the rate of production of high-energy phosphate compounds (eg, adenosine triphosphate). It is now recognized that this view is simplistic and that mitochondria play key roles in many other processes, including cell signaling, regulating gene expression, modulating cellular calcium levels, and influencing the activation of cell death pathways (eg, caspase activation). Moreover, these multiple mitochondrial functional characteristics are now known to influence the evolution of cellular and organ function in many disease states, including sepsis, ICU-acquired skeletal muscle dysfunction, acute lung injury, acute renal failure, and critical illness-related immune function dysregulation. In addition, diseased mitochondria generate toxic compounds, most notably released mitochondrial DNA, which can act as danger-associated molecular patterns to induce systemic toxicity and damage multiple organs throughout the body. This article reviews these evolving concepts relating mitochondrial function and acute illness. The discussion is organized into four sections: (1) basics of mitochondrial physiology; (2) cellular mechanisms of mitochondrial pathophysiology; (3) critical care disease processes whose initiation and evolution are shaped by mitochondrial pathophysiology; and (4) emerging treatments for mitochondrial dysfunction in critical illness.

Mitochondrial dysfunction mediated through dynamin-related protein 1 (Drp1) propagates impairment in blood brain barrier in septic encephalopathy

Background

Out of the myriad of complications associated with septic shock, septic-associated encephalopathy (SAE) carries a significant risk of morbidity and mortality. Blood-brain-barrier (BBB) impairment, which subsequently leads to increased vascular permeability, has been associated with neuronal injury in sepsis. Thus, preventing BBB damage is an attractive therapeutic target. Mitochondrial dysfunction is an important contributor of sepsis-induced multi-organ system failure. More recently, mitochondrial dysfunction in endothelial cells has been implicated in mediating BBB failure in stroke, multiple sclerosis and in other neuroinflammatory disorders. Here, we focused on Drp1-mediated mitochondrial dysfunction in endothelial cells as a potential target to prevent BBB failure in sepsis.

Methods

We used lipopolysaccharide (LPS) to induce inflammation and BBB disruption in a cell culture as well as in murine model of sepsis. BBB disruption was assessed by measuring levels of key tight-junction proteins. Brain cytokines levels, oxidative stress markers, and activity of mitochondrial complexes were measured using biochemical assays. Astrocyte and microglial activation were measured using immunoblotting and qPCR. Transwell cultures of brain microvascular endothelial cells co-cultured with astrocytes were used to assess the effect of LPS on expression of tight-junction proteins, mitochondrial function, and permeability to fluorescein isothiocyanate (FITC) dextran. Finally, primary neuronal cultures exposed to LPS were assessed for mitochondrial dysfunction.

Results

LPS induced a strong brain inflammatory response and oxidative stress in mice which was associated with increased Drp1 activation and mitochondrial localization. Particularly, Drp1-(Fission 1) Fis1-mediated oxidative stress also led to an increase in expression of vascular permeability regulators in the septic mice. Similarly, mitochondrial defects mediated via Drp1-Fis1 interaction in primary microvascular endothelial cells were associated with increased BBB permeability and loss of tight-junctions after acute LPS injury. P110, an inhibitor of Drp1-Fis1 interaction, abrogated these defects, thus indicating a critical role for this interaction in mediating sepsis-induced brain dysfunction. Finally, LPS mediated a direct toxic effect on primary cortical neurons, which was abolished by P110 treatment.

Conclusions

LPS-induced impairment of BBB appears to be dependent on Drp1-Fis1-mediated mitochondrial dysfunction. Inhibition of mitochondrial dysfunction with P110 may have potential therapeutic significance in septic encephalopathy.

Hepatoprotective Effect of the Ethanol Extract of Illicium henryi against Acute Liver Injury in Mice Induced by Lipopolysaccharide

The root bark of Illicium henryi has been used in traditional Chinese medicine to treat lumbar muscle strain and rheumatic pain. Its ethanol extract (EEIH) has been previously reported to attenuate lipopolysaccharide (LPS)-induced acute kidney injury in mice. The present study aimed to evaluate the in vitro antioxidant activities and in vivo protective effects of EEIH against LPS-induced acute liver injury (ALI) in mice as well as explore its molecular mechanisms. The mice were injected intraperitoneally (i.p.) with EEIH at the doses of 1.25, 2.5, and 5.0 mg/kg every day for 5 days. One hour after the last administration, the mice were administered i.p. with LPS (8 mg/kg). After fasting for 12 h, blood and liver tissues were collected to histopathological observation, biochemical assay, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot analyses. EEIH possessed 2,2-diphenyl-1-picrylhydrazil (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiozoline-6-sulfonic acid) disodium salt (ABTS) radical scavenging activities and ferric-reducing antioxidant capacity in vitro. The histopathological examination, serum biochemical analysis, and liver myeloperoxidase (MPO) activity showed that EEIH pretreatment alleviated LPS-induced liver injury in mice. EEIH significantly dose-dependently decreased the mRNA and protein expression levels of inflammatory factors TNF-α, IL-1β, IL-6, and COX-2 in liver tissue of LPS-induced ALI mice via downregulating the mRNA and protein expressions of toll-like receptor 4 (TLR4) and inhibiting the phosphorylation of nuclear factor-κB (NF-κB) p65. Furthermore, EEIH markedly ameliorated liver oxidative and nitrosative stress burden in LPS-treated mice through reducing the content of thiobarbituric acid reactive substances (TBARS), inducible nitric oxide synthase (iNOS), and nitric oxide (NO) levels, restoring the decreased superoxide dismutase (SOD) and reduced glutathione (GSH) levels, and up-regulating nuclear factor erythroid 2 related factor 2 (Nrf2). These results demonstrate that EEIH has protective effects against ALI in mice via alleviating inflammatory response, oxidative and nitrosative stress burden through activating the Nrf2 and suppressing the TLR4/NF-κB signaling pathways. The hepatoprotective activity of EEIH might be attributed to the flavonoid compounds such as catechin (1), 3',4',7-trihydroxyflavone (2), and taxifolin (7) that most possibly act synergistically.

Mitochondrial Damage and Mitochondria-Targeted Antioxidant Protection in LPS-Induced Acute Kidney Injury

Induced and frequently unwanted alterations in the mitochondrial structure and functions are a key component of the pathological cascade in many kidney pathologies, including those associated with acute damage. One of the principal pathogenic elements causing mitochondrial dysfunction in Acute Kidney Injury (AKI) is oxidative stress. After ischemia and nephrotoxic action of drugs, sepsis and systemic inflammation are the most frequent causes of AKI. As the kidney suffers from oxidative stress during sepsis, one of the most promising approaches to alleviate such damaging consequences is the use of antioxidants. Considering administration of lipopolysaccharide (LPS) as a model of sepsis, we demonstrate that the mitochondria of neonatal renal tissue are severely affected by LPS-induced AKI, with pathological ultrastructural changes observed in both the mitochondria of the renal tubular epithelium and the vascular endothelium. Upon mitochondrial damage, we evaluated the effect of the mitochondria-targeted antioxidant plastoquinol decylrhodamine 19 (SkQR1) on the development of acute renal failure in newborn rats associated with systemic inflammation induced by the administration of LPS. We found that SkQR1 administration 3 h before LPS led to decreased urinal expression of the AKI marker neutrophil gelatinase-associated lipocalin 2 (NGAL), in addition to a decrease in urea and creatinine levels in the blood. Additionally, an observed impairment of proliferative activity in the neonatal kidney caused by LPS treatment was also prevented by the treatment of rat pups with SkQR1. Thus, one of the key events for renal tissue damage in neonatal sepsis is an alteration in the structure and function of the mitochondria and the mitochondria-targeted antioxidant SkQR1 is an effective nephroprotective agent, which protects the neonatal kidney from sepsis-induced AKI.

HIPK1 Interference Attenuates Inflammation and Oxidative Stress of Acute Lung Injury via Autophagy

<strong>BACKGROUND</strong> Acute respiratory distress syndrome (ARDS), which is characterized by severe hypoxemia (PaO2/FIO2 ≤300 mmHg), is usually companied by uncontrolled inflammation, oxidative injury, and the damage to the alveolar-capillary barrier. Severe ARDS is usually companied with acute lung injury that worsen the patients' condition. HIPK1 is a modulator of homeodomain-containing transcription factors and regulates multiple cellular biological process associated with inflammation and anti-stress responses. <strong>MATERIAL AND METHODS</strong> We used an LPS-induced mouse acute lung injury (ALI) model to investigate the possible role of HIPK1 in ALI pathophysiology. <strong>RESULTS</strong> We found the HIPK1 was elevated in ALI model mice while interference of HIPK1 by siRNA attenuated the inflammation and oxidative stress indicators (H2O2, O-2, and NO). Further research found HIPK1 interference enhanced the autophagy. <strong>CONCLUSIONS</strong> Decreased HIPK1 in ALI showed protective effects in attenuating inflammation and oxidative stress and enhancing autophagy, indicating HIPK1 as a possible target in ALI management.

Potential therapy strategy: targeting mitochondrial dysfunction in sepsis

Recently, the definition of sepsis was concluded to be a life-threatening organ dysfunction caused by a dysregulated host response to infection. Severe patients always present with uncorrectable hypotension or hyperlactacidemia, which is defined as septic shock. The new definition emphasizes dysregulation of the host response and multiple organ dysfunction, which is partially attributed to metabolic disorders induced by energy crisis and oxidative stress. Mitochondria are a cellular organelle that are well known as the center of energy production, and mitochondrial damage or dysfunction is commonly induced in septic settings and is a predominant factor leading to a worse prognosis. In the present review, we determine the major mitochondrial disorders from morphology to functions in sepsis. In the following, several clinical or pre-clinical assays for monitoring mitochondrial function are demonstrated according to accumulated evidence, which is the first step of specific therapy targeting to modulate mitochondrial function. Accordingly, various reagents used for regulating mitochondrial enzyme activities and promoting biogenesis have been documented, among which mitochondria-targeted cation, TPP-conjugated antioxidants are the most valuable for future trials and clinical treatment to improve mitochondrial function as they may take advantage of the prognosis associated with septic complications.

Time course of liver mitochondrial function and intrinsic changes in oxidative phosphorylation in a rat model of sepsis

Background

Tissue ATP depletion and oxidative stress have been associated with the severe outcomes of septic shock. One of the compensatory mechanisms to alleviate the sepsis-induced mitochondrial dysfunction could be the increase in oxidative phosphorylation efficiency (ATP/O). We propose to study liver mitochondrial function and oxidative stress and the regulatory mechanism of mitochondrial oxidative phosphorylation efficiency in an animal model of sepsis.

Methods

We induced sepsis in rats by cecal ligation and perforation (CLP). Six, 24, or 36 h following CLP, we measured liver mitochondrial respiration, cytochrome c oxidase activity, and membrane permeability. We determine oxidative phosphorylation efficiency, by measuring ATP synthesis related to oxygen consumption at various exogenous ADP concentrations. Finally, we measured radical oxygen species (ROS) generation by liver mitochondria and mRNA concentrations of UCP2, biogenesis factors, and cytokines at the same end points.

Results

CLP rats presented hypotension, lactic acidosis, liver cytolysis, and upregulation of proinflammatory cytokines mRNA as compared to controls. Liver mitochondria showed a decrease in ATP synthesis and oxygen consumption at 24 h following CLP. A marked uncoupling of oxidative phosphorylation appeared 36 h following CLP and was associated with a decrease in cytochrome c oxidase activity and content and ATP synthase subunit β content (slip mechanism) and an increase in mitochondrial oligomycin-insensitive respiration, but no change in mitochondrial inner membrane permeability (no leak). Upregulation of UCP2 mRNA resulted in a decrease in mitochondrial ROS generation 24 h after the onset of CLP, whereas ROS over-generation associated with slip at cytochrome c oxidase observed at 36 h was concomitant with a decrease in UCP2 mRNA expression.

Conclusions

Despite a compensatory increase in mitochondrial biogenesis factors, liver mitochondrial functions remain altered after CLP. This suggests that the functional compensatory mechanisms reported in the present study (slip at cytochrome c oxidase and biogenesis factors) were not strong enough to increase oxidative phosphorylation efficiency and failed to limit liver mitochondrial ROS over-generation. These data suggest that treatments based on cytochrome c infusion could have a role in mitochondrial dysfunction and/or ROS generation associated with sepsis.

Electronic supplementary material

The online version of this article (10.1186/s40635-018-0197-y) contains supplementary material, which is available to authorized users.

Sophocarpine Attenuates LPS-Induced Liver Injury and Improves Survival of Mice through Suppressing Oxidative Stress, Inflammation, and Apoptosis

Septic liver injury/failure that is mainly characterized by oxidative stress, inflammation, and apoptosis led to a great part of terminal liver pathology with limited effective intervention. Here, we used a lipopolysaccharide (LPS) stimulation model to simulate the septic liver injury and investigated the effect of sophocarpine on LPS-stimulated mice with endotoxemia. We found that sophocarpine increases the survival rate of mice and attenuates the LPS-induced liver injury, which is indicated by pathology and serum liver enzymes. Further research found that sophocarpine ameliorated hepatic oxidative stress indicators (H₂O₂, O₂^∙−, and NO) and enhanced the expression of antioxidant molecules such as superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). In addition, sophocarpine also attenuated regional and systematic inflammation and further reduced apoptosis of hepatocytes. Mechanistic evidence was also investigated in the present study as sophocarpine inhibited hepatic expression of the CYP2E/Nrf2 pathway during oxidative stress, inactivated p38/JNK cascade and NF-κB pathway, and, meanwhile, suppressed PI3K/AKT signaling that reduced apoptosis. Conclusively, the present study unveiled the protective role of sophocarpine in LPS-stimulated oxidative reaction, inflammation, and apoptosis by suppressing the CYP2E/Nrf2/ROS as well as PI3K/AKT pathways, suggesting its promising role in attenuating inflammation and liver injury of septic endotoxemia.

Effects of Erdosteine in Experimental Sepsis Model in Rats

Objective

Erdosteine is a mucolytic agent that is known to possess antioxidant effects. This study investigated the effects of erdosteine on endothelin-1 (ET-1) levels and oxidative stress parameters superoxide dismutase (SOD) and malondialdehyde (MDA) in a rat sepsis model.

Methods

Four groups of Wistar albino rats (n=8 per group) were randomly allocated to the following groups: sham (group 1), sepsis (group 2), erdosteine control (group 3) and a sepsis group pretreated with erdosteine (group 4). Sepsis was induced using E. Coli ATCC 25922 inoculation. Serum ET-1, liver tissue SOD and MDA levels were determined in all groups.

Results

ET-1 levels were significantly higher in group 2 compared to groups 1, 3 and 4 (p<0.001, p=0.002 and p<0.001, respectively). Similarly, MDA levels in groups 1, 3 and 4 were significantly lower relative to group 2 (p<0.001, p=0.022 and p=0.010, respectively). Additionally, SOD activities in these same three groups were found to be significantly higher than those in group 2 (p<0.001, p=0.004 and p=0.028, respectively).

Conclusion

In conclusion, erdosteine decreases ET-1 levels and ameliorates oxidative stress parameters induced by sepsis in an experimental rat model of sepsis.

Evidence of Oxidative Stress and Secondary Mitochondrial Dysfunction in Metabolic and Non-Metabolic Disorders

Mitochondrial dysfunction and oxidative stress have been implicated in the pathogenesis of a number of diseases and conditions. Oxidative stress occurs once the antioxidant defenses of the body become overwhelmed and are no longer able to detoxify reactive oxygen species (ROS). The ROS can then go unchallenged and are able to cause oxidative damage to cellular lipids, DNA and proteins, which will eventually result in cellular and organ dysfunction. Although not always the primary cause of disease, mitochondrial dysfunction as a secondary consequence disease of pathophysiology can result in increased ROS generation together with an impairment in cellular energy status. Mitochondrial dysfunction may result from either free radical-induced oxidative damage or direct impairment by the toxic metabolites which accumulate in certain metabolic diseases. In view of the importance of cellular antioxidant status, a number of therapeutic strategies have been employed in disorders associated with oxidative stress with a view to neutralising the ROS and reactive nitrogen species implicated in disease pathophysiology. Although successful in some cases, these adjunct therapies have yet to be incorporated into the clinical management of patients. The purpose of this review is to highlight the emerging evidence of oxidative stress, secondary mitochondrial dysfunction and antioxidant treatment efficacy in metabolic and non-metabolic diseases in which there is a current interest in these parameters.

IGF-1 may predict the severity and outcome of patients with sepsis and be associated with microRNA-1 level changes

IGF-1 functions as an anti-oxidative stress molecule and some critical patients with sepsis have a lower level of serum IGF-1. However, the association between IGF-1 and the severity or prognosis of sepsis remains unclear. This study aimed to elucidate the relationship between serum IGF-1 levels and the severity and prognosis of sepsis, and the possible mechanism was analyzed. Clinical characteristics of patients with sepsis were recorded and analyzed. Serum IGF-1 levels and micro (mi)RNA-1 levels were tested using radioimmunoassay and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis, respectively. The A549 cell line and HKC cell line were cultured in vitro and exposed to H₂O₂ with or without IGF-1 treatment. Cell death was detected by analyzing cell death markers via ELISA kits, and miRNA-1 levels were detected after H₂O₂ exposure using RT-qPCR analysis. miRNA-1 in cells was upregulated by transfection and IGF-1 mRNA was detected to determine its relationship with miRNA-1. Once again, cell ELISA kits were used to analyze cell death markers after transfection. Serum IGF-1 levels were reduced in patients with sepsis, whereas miRNA-1 levels were higher (P<0.05 vs. healthy control). Patients in the septic shock subgroup or dead patients had the lowest IGF-1 levels and the highest miRNA-1 levels (P<0.05 vs. sepsis and severe sepsis). IGF-1 levels were inversely proportional to the miRNA-1 level. In vitro, IGF-1 reduced the cell death caused by H₂O₂. miRNA-1 transfection effectively increased the sensitivity of cells to H₂O₂ damage by reducing the expression of IGF-1, which was able to prevent cells from injury caused by H₂O₂. The transfection of negative control miRNA did not influence the level of IGF-1 miRNA and the sensitivity to H₂O₂ damage. In conclusion, low IGF-1 levels in patients with sepsis may predict increased severity of the condition and poor prognosis. The possible mechanism is that the excessive miRNA-1 levels reduce IGF-1 levels, resulting in insufficient anti-oxidative action by IGF-1 which increases the injury caused by oxidative stress in patients with sepsis.

Intraperitoneal gardiquimod protects against hepatotoxicity through inhibition of oxidative stress and inflammation in mice with sepsis

Many reports recapitulate the contribution of reactive oxygen species (ROS) over-accumulation to the organ damage; it is of significance to strictly target ROS production. In this study, we evaluated the potential role of TLR7 agonist gardiquimod (GDQ) in oxidative stress (OS) in liver injury induced by sepsis. Here, we observed that intraperitoneal pretreatment with GDQ dramatically elevated the septic survival rate and effectively attenuated the septic liver injury. Interestingly, the increased ROS and inflammatory factor IL-6 levels were reversed after GDQ intervention. Subsequently, Western blot was employed to determine the definite mechanism. As expected, it was showed that the upregulation of c-Jun N-terminal kinase (JNK)/c-Jun pathway in liver of septic animals was considerably suppressed by GDQ pre-exposure. Our current result highlight that pre-administration of GDQ ameliorated sepsis induced hepatotoxicity and reduced the generation of IL-6 and OS responses, which was associated with downregulation of JNK/c-Jun pathway. Our strategies might be ultimately beneficial in mitigating liver injury symptom.

Endotoxemia accelerates diaphragm dysfunction in ventilated rabbits

BACKGROUND

Ventilators may induce diaphragm dysfunction, and most of the septic population who are admitted to the intensive care unit require mechanical ventilation. However, there is no evidence that sepsis accelerates the onset of ventilator-induced diaphragm dysfunction or affects the microcirculation. Our study investigated whether lipopolysaccharide (LPS)-induced endotoxemia accelerated diaphragm dysfunction in ventilated rabbits by evaluating microcirculation, lipid accumulation, and diaphragm contractility.

METHODS

After anesthesia and tracheostomy, 25 invasively monitored and mechanically ventilated New Zealand white rabbits were randomized to control (n = 5), controlled mechanical ventilation (CMV) (n = 5), pressure support ventilation (PSV; n = 5), CMV or PSV with LPS-induced endotoxemia (CMV-LPS and PSV-LPS, respectively; n = 5 for each). Rabbits were anesthetized and ventilated for 24 h, except the control rabbits (30 min). Diaphragmatic contractility was evaluated using neuromechanical and neuroventilatory efficiency. We evaluated the following at the end of the protocol: (1) diaphragm microcirculation; (2) lipid accumulation; and (3) diaphragm muscular fibers structure.

RESULTS

Diaphragm contractility, microcirculation, lipid accumulation, and fiber structures were severely compromised in endotoxemic animals after 24 h compared to nonendotoxemic rabbits. Moreover, a slight but significant increase in lipid accumulation was observed in CMV and PSV groups compared with controls (P < 0.05).

CONCLUSIONS

Endotoxemia accelerates the diaphragm dysfunction process in ventilated rabbits, affects the microcirculation, and results in diaphragmatic lipid accumulation and contractility impairment.

Does rosmarinic acid treatment have protective role against sepsis-induced oxidative damage in Wistar Albino rats?

Reactive oxygen species are believed to be involved in the development of sepsis. Plant-derived phenolic compounds are thought to be possible therapeutic agents against sepsis because of their antioxidant properties. Rosmarinic acid (RA) is a phenolic compound commonly found in various plants, which has many biological activities including antioxidant activity. The aim of this study was to investigate the effects of RA on sepsis-induced DNA damage in the lymphocytes and liver and kidney cells of Wistar albino rats by alkaline comet assay with and without formamidopyrimidine DNA glycosylase protein. The oxidative stress parameters such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and total glutathione (GSH) and malondialdehyde (MDA) levels in the liver and kidney tissues and an inflammatory cytokine, tumor necrosis factor α (TNF-α) level in plasma were also evaluated. It is found that DNA damage in the lymphocytes, livers, and kidneys of the RA-treated rats was significantly lower than that in the sepsis-induced rats. RA treatment also decreased the MDA levels and increased the GSH levels and SOD and GSH-Px activities in the livers and kidneys of the sepsis-induced rats. Plasma TNF-α level was found to be decreased in the RA-treated rats. It seems that RA might have a role in the attenuation of sepsis-induced oxidative damage not only by decreasing the DNA damage but also by increasing the antioxidant status and DNA repair capacity of the animals.

MITOCHONDRIAL FUNCTION IN SEPSIS

Mitochondria are an essential part of the cellular infrastructure, being the primary site for high-energy adenosine triphosphate production through oxidative phosphorylation. Clearly, in severe systemic inflammatory states, like sepsis, cellular metabolism is usually altered, and end organ dysfunction is not only common, but also predictive of long-term morbidity and mortality. Clearly, interest is mitochondrial function both as a target for intracellular injury and response to extrinsic stress have been a major focus of basic science and clinical research into the pathophysiology of acute illness. However, mitochondria have multiple metabolic and signaling functions that may be central in both the expression of sepsis and its ultimate outcome. In this review, the authors address five primary questions centered on the role of mitochondria in sepsis. This review should be used both as a summary source in placing mitochondrial physiology within the context of acute illness and as a focal point for addressing new research into diagnostic and treatment opportunities these insights provide.

Blood-cell bioenergetics are associated with physical function and inflammation in overweight/obese older adults

BACKGROUND

Physical function and strength decline with age and lead to limited mobility and independence in older adults. Alterations in mitochondrial function are thought to underlie numerous age-related changes, including declining physical ability. Recent studies suggest that systemic changes in bioenergetic capacity may be reported by analyzing mitochondrial function in circulating cells. The objective of this study was to determine whether the bioenergetic capacity of peripheral blood mononuclear cells (PBMCs) is related to differences in physical function among older, overweight/obese, adults. To address this, we tested the hypothesis that greater PBMC respirometric capacity would be associated with better physical function, muscular strength, leg lean mass, and muscle quality. Furthermore, we tested whether the respirometric capacity of PBMCs is related to cellular composition and inflammatory status reported by interleukin-6 (IL-6).

METHODS

Fasted PBMC respiration (pmol/min/500,000 cells), expanded short physical performance battery (Ex-SPPB), peak knee extensor (KE) strength (Nm), grip strength (kg), leg lean mass (kg, via dual energy X-ray absorptiometry [DXA]), muscle quality (Nm/kg), and plasma IL-6 (pg/mL) were analyzed in 15 well-functioning, community-dwelling, sedentary overweight/obese older men (n=9) and women (n=6) aged 65 to 78 (mean 68.3 ± 3.5 years). Pearson and partial correlations were calculated to determine associations between PBMC respiration and these variables.

RESULTS

Higher maximal respiration of PBMCs was associated with better Ex-SPPB (r=0.58, p=0.02), greater KE strength (r=0.60, p=0.02), greater grip strength (r=0.52, p=0.05) and lower IL-6 (r=-0.58, p=0.04). Higher spare respiratory capacity was associated with better Ex-SPPB (r=0.59, p=0.02), greater KE strength (r=0.60, p=0.02), greater grip strength (r=0.54, p=0.04), greater leg muscle quality (r=0.56, p=0.04), and lower IL-6 (r=-0.55, p=0.05). Monocyte and lymphocyte counts were not related to PBMC respiratory capacity.

CONCLUSIONS

Our results indicate that respirometric profiles of readily obtainable blood cells are associated with physical function and strength. Future studies should be undertaken in order to determine whether blood-based bioenergetic profiling can provide an objective index of systemic mitochondrial health.

Inhibition of MAP kinase/NF-kB mediated signaling and attenuation of lipopolysaccharide induced severe sepsis by cerium oxide nanoparticles

Sepsis is a life threatening disease that is associated with high mortality. Existing treatments have failed to improve survivability in septic patients. The purpose of this present study is to evaluate whether cerium oxide nanoparticles (CeO2NPs) can prevent lipopolysaccharide (LPS) induced severe sepsis mortality by preventing hepatic dysfunction in male Sprague Dawley rats. Administration of a single dose (0.5 mg/kg) of CeO2NPs intravenously to septic rats significantly improved survival rates and functioned to restore body temperature, respiratory rate and blood pressure towards baseline. Treatment-induced increases in animal survivability were associated with decreased hepatic damage along with reductions in serum cytokines/chemokines, and diminished inflammatory related signaling. Kupffer cells and macrophage cells exposed to CeO2NPs exhibited decreases in LPS-induced cytokine release (TNF-α, IL-1β, IL-6, HMGB1) which were associated with diminished cellular ROS, reduced levels of nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), and decreased nuclear factor-kappa light chain enhancer of activated B cells (NF-kB) transcriptional activity. The findings of this study indicate that CeO2NPs may be useful as a therapeutic agent for sepsis.

Changes in mitochondrial enzymatic activities of monocytes during prolonged hypobaric hypoxia and influence of antioxidants: A randomized controlled study

OBJECTIVES

Exposure to high altitudes is associated with oxidative cellular damage due to the increased level of reactive oxygen and nitrogen species and altered activity of antioxidant systems. Subjects were submitted to prolonged hypoxia, to evaluate changes in mitochondrial enzyme activities of monocytes and their attenuation by supplementation with antioxidants.

METHODS

Twelve subjects were randomly assigned to receive antioxidant supplements or placebo prior to and during an expedition to Pik Lenin (7145 m). Monocytes were isolated from blood samples to determine the activity of mitochondrial enzymes cytochrome c oxidase and citrate synthase at 490 m (baseline) and at the altitudes of 3550 m, 4590 m, and 5530 m.

RESULTS

An increase in citrate synthase activity at all altitudes levels was observed. Hypoxia induced an increase in the activity of cytochrome c oxidase only at 4590 m. Neither citrate synthase activity nor cytochrome c oxidase activity differed between the subjects receiving antioxidant supplements and those receiving placebo.

CONCLUSIONS

Hypoxia leads to an increase in citrate synthase activity of monocyte mitochondria as a marker of mitochondrial mass, which is not modified by antioxidant supplementation. The increase in mitochondrial mass may represent a compensatory mechanism to preserve oxidative phosphorylation of monocytes at high altitudes.

Value of caffeic acid phenethyl ester pretreatment in experimental sepsis model in rats

Background and Aim. The aim of this study was to determine the actions of caffeic acid phenethyl ester (CAPE) on the changes of endothelin-1 (ET-1) level, tumor necrosis factor- (TNF-) alpha, and oxidative stress parameters such as superoxide dismutase (SOD) activities and malondialdehyde (MDA) levels in experimental sepsis model in rats. Materials and Methods. Twenty-four rats were randomly divided into three experimental groups: sham (group 1), sepsis (group 2), and sepsis + CAPE (group 3), n = 8 each. CAPE was administered (10 µmol/kg) intraperitoneally to group 3 before sepsis induction. Serum ET-1, serum TNF-alpha, tissue SOD activity, and tissue MDA levels were measured in all groups. Results. Pretreatment with CAPE decreased ET-1, TNF-alpha, and MDA levels in sepsis induced rats. Additionally SOD activities were higher in rats pretreated with CAPE after sepsis induction. Conclusion. Our results demonstrate that CAPE may have a beneficial effect on ET and TNF-alpha levels and oxidative stress parameters induced by sepsis in experimental rat models. Therefore treatment with CAPE can be used to avoid devastating effects of sepsis.

Effect of cerium oxide nanoparticles on sepsis induced mortality and NF-κB signaling in cultured macrophages

Aim: To investigate whether cerium oxide (CeO2) nanoparticles could be used for the treatment of severe sepsis. Materials & methods: Cecal peritonitis was induced in male Sprague–Dawley rats in the presence and absence of CeO2 nanoparticles. Cultured macrophages (RAW264.7 cells) were challenged with lipopolysaccharide in the absence and presence of CeO2 nanoparticles. The effect of nanoparticles on the growth of Escherichia coli and Staphylococcus aureus was determined in culture. Results: Nanoparticle treatment decreased sepsis-induced mortality, organ damage, serum IL-6, blood urea nitrogen and inflammatory markers. Nanoparticle treatment diminished lipopolysaccharide-induced cytokine release and p65-nuclear factor-KB (NF-KB) activation in cultured RAW264.7 cells. Exposure to CeO2 nanoparticles inhibited E. coli growth. Conclusion: The findings of this study indicate that CeO2 nanoparticles may be useful for the treatment of sepsis.

Mitochondria-Targeted Peptide Reverses Mitochondrial Dysfunction and Cognitive Deficits in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is associated with increased mortality, morbidity, and long-term cognitive impairments. Its pathophysiology remains to be determined and an effective pharmacologic treatment is lacking. The goal of this study was to investigate the effects of the mitochondria-targeted peptide SS-31 on mitochondrial function and cognitive deficits in SAE mice. C57BL/6 male mice were randomly divided into sham, sham + SS-31, cecal ligation and puncture (CLP), and CLP + SS-31 groups. Peptide SS-31 (5 mg/kg) was intraperitoneally administrated immediately after operation and afterwards once daily for six consecutive days. Surviving mice were subjected to behavioral tests and the hippocampus was collected for biochemical analysis 7 days after operation. The results showed that CLP resulted in high mortality rate and cognitive deficits, representative characteristics of SAE. A physiological mechanistic investigation revealed that mitochondrial function of hippocampus was severely impaired, coupled with reactive oxygen species (ROS) generation, triggering neuronal apoptosis and inflammation. Notably, administration of peptide SS-31 protected the integrity of mitochondria, reversed the mitochondrial dysfunction, inhibited the apoptosis resulting from the release of cytochrome c, diminished the response of inflammation, and ultimately reversed the behavior deficits in the SAE mice. In conclusion, our data demonstrate that daily treatment with mitochondria-targeted peptide SS-31 reduces mortality rate and ameliorates cognitive deficits, which is possibly through a mechanism of reversing mitochondrial dysfunction and partial inhibition of neuronal apoptosis and inflammation in the hippocampus of the SAE mice.

Endothelial dysfunction is a potential contributor to multiple organ failure and mortality in aged mice subjected to septic shock: preclinical studies in a murine model of cecal ligation and puncture

INTRODUCTION

The goal of the current study was to investigate the effect of aging on the development of endothelial dysfunction in a murine model of sepsis, and to compare it with the effect of genetic deficiency of the endothelial isoform of nitric oxide synthase (eNOS).

METHODS

Cecal ligation and puncture (CLP) was used to induce sepsis in mice. Survival rates were monitored and plasma indices of organ function were measured. Ex vivo studies included the measurement of vascular function in thoracic aortic rings, assessment of oxidative stress/cellular injury in various organs and the measurement of mitochondrial function in isolated liver mitochondria.

RESULTS

eNOS deficiency and aging both exacerbated the mortality of sepsis. Both eNOS-deficient and aged mice exhibited a higher degree of sepsis-associated multiple organ dysfunction syndrome (MODS), infiltration of tissues with mononuclear cells and oxidative stress. A high degree of sepsis-induced vascular oxidative damage and endothelial dysfunction (evidenced by functional assays and multiple plasma markers of endothelial dysfunction) was detected in aortae isolated from both eNOS(-/-) and aged mice. There was a significant worsening of sepsis-induced mitochondrial dysfunction, both in eNOS-deficient mice and in aged mice. Comparison of the surviving and non-surviving groups of animals indicated that the severity of endothelial dysfunction may be a predictor of mortality of mice subjected to CLP-induced sepsis.

CONCLUSIONS

Based on the studies in eNOS mice, we conclude that the lack of endothelial nitric oxide production, on its own, may be sufficient to markedly exacerbate the severity of septic shock. Aging markedly worsens the degree of endothelial dysfunction in sepsis, yielding a significant worsening of the overall outcome. Thus, endothelial dysfunction may constitute an early predictor and independent contributor to sepsis-associated MODS and mortality in aged mice.

The protective role of ferulic acid on sepsis-induced oxidative damage in Wistar albino rats

Oxidative stress has an important role in the development of sepsis-induced multiorgan failure. Ferulic acid (FA), a well-established natural antioxidant, has several pharmacological activities including anti-inflammatory, anticancer and hepatoprotective. This study aimed to investigate the effects of FA on sepsis-induced oxidative damage in Wistar albino rats. Sepsis-induced DNA damage in the lymphocytes, liver and kidney cells of rats were evaluated by comet assay with and without formamidopyrimidine DNA glycosylase (Fpg). The oxidative stress parameters such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and total glutathione (GSH) and malondialdehyde (MDA) levels were also measured. It is found that DNA damage in sepsis+FA-treated group was significantly lower than the sepsis group. FA treatment also decreased the MDA levels and increased the GSH levels and SOD and GSH-Px activities in the sepsis-induced rats. It seems that FA might have ameliorative effects against sepsis-induced oxidative damage.

Early identification and management of patients with severe sepsis and septic shock in the emergency department

Severe sepsis and septic shock have great relevance to Emergency Medicine physicians because of their high prevalence, morbidity, and mortality. Treatment is time-sensitive, depends on early identification risk stratification, and has the potential to significantly improve patient outcomes. In this article, we review the pathophysiology of, and evidence basis for, the emergency department management of severe sepsis and septic shock.

Energy crisis: the role of oxidative phosphorylation in acute inflammation and sepsis

Mitochondrial dysfunction is increasingly recognized as an accomplice in most of the common human diseases including cancer, neurodegeneration, diabetes, ischemia/reperfusion injury as seen in myocardial infarction and stroke, and sepsis. Inflammatory conditions, both acute and chronic, have recently been shown to affect mitochondrial function. We here discuss the role of oxidative phosphorylation (OxPhos), focusing on acute inflammatory conditions, in particular sepsis and experimental sepsis models. We discuss mitochondrial alterations, specifically the suppression of oxidative metabolism and the role of mitochondrial reactive oxygen species in disease pathology. Several signaling pathways including metabolic, proliferative, and cytokine signaling affect mitochondrial function and appear to be important in inflammatory disease conditions. Cytochrome c oxidase (COX) and cytochrome c, the latter of which plays a central role in apoptosis in addition to mitochondrial respiration, serve as examples for the entire OxPhos system since they have been studied in more detail with respect to cell signaling. We propose a model in which inflammatory signaling leads to changes in the phosphorylation state of mitochondrial proteins, including Tyr304 phosphorylation of COX catalytic subunit I. This results in an inhibition of OxPhos, a reduction of the mitochondrial membrane potential, and consequently a lack of energy, which can cause organ failure and death as seen in septic patients.

Evidence of oxidative stress and mitochondrial respiratory chain dysfunction in an in vitro model of sepsis-induced kidney injury

To investigate the role of oxidative stress and/or mitochondrial impairment in the occurrence of acute kidney injury (AKI) during sepsis, we developed a sepsis-induced in vitro model using proximal tubular epithelial cells exposed to a bacterial endotoxin (lipopolysaccharide, LPS). This investigation has provided key features on the relationship between oxidative stress and mitochondrial respiratory chain activity defects. LPS treatment resulted in an increase in the expression of inducible nitric oxide synthase (iNOS) and NADPH oxidase 4 (NOX-4), suggesting the cytosolic overexpression of nitric oxide and superoxide anion, the primary reactive nitrogen species (RNS) and reactive oxygen species (ROS). This oxidant state seemed to interrupt mitochondrial oxidative phosphorylation by reducing cytochrome c oxidase activity. As a consequence, disruptions in the electron transport and the proton pumping across the mitochondrial inner membrane occurred, leading to a decrease of the mitochondrial membrane potential, a release of apoptotic-inducing factors and a depletion of adenosine triphosphate. Interestingly, after being targeted by RNS and ROS, mitochondria became in turn producer of ROS, thus contributing to increase the mitochondrial dysfunction. The role of oxidants in mitochondrial dysfunction was further confirmed by the use of iNOS inhibitors or antioxidants that preserve cytochrome c oxidase activity and prevent mitochondrial membrane potential dissipation. These results suggest that sepsis-induced AKI should not only be regarded as failure of energy status but also as an integrated response, including transcriptional events, ROS signaling, mitochondrial activity and metabolic orientation such as apoptosis.

Early septic shock induces loss of oxidative phosphorylation yield plasticity in liver mitochondria

We aimed to study the change in mitochondrial oxidative phosphorylation efficiency occurring at the early stage of septic shock in an experimental model. Thirty-six male Wistar rats were divided into two groups. In the first group, a cecal ligation and puncture (CLP) was carried out to induce septic shock for 5 h. The second group includes sham-operated rats and constitutes the control group. Blood gas analysis, alanine amino transferase, and lactic acid dosages were assayed 5 h after surgery. Liver mitochondria were isolated for in vitro functional characterization, including mitochondrial respiratory parameters, oxidative phosphorylation efficiency, oxi-radical production, membrane potential, and cytochrome c oxidase activity and content. Liver interleukin 1β (IL-1β) and tumor necrosis α mRNA levels were determined. Septic shock induced a severe hypotension occurring 180 min after CLP in association with a metabolic acidosis, an increase in plasma alanine amino transferase, liver IL-1β gene expression, and mitochondrial reactive oxygen species production. The rates of mitochondrial oxygen consumption and the activity and content of cytochrome c oxidase were significantly decreased while no alterations in the oxidative phosphorylation efficiency and inner membrane integrity were found. These results show that contrary to what was expected, liver mitochondria felt to adjust their oxidative phosphorylation efficiency in response to the decrease in the mitochondrial oxidative activity induced by CLP. This loss of mitochondrial bioenergetics plasticity might be related to mitochondrial oxidative stress and liver cytokines production.