α-Lipoic acid protects mitochondrial enzymes and attenuates lipopolysaccharide-induced hypothermia in mice

Hypothermia is a key symptom of sepsis, but the mechanism(s) leading to hypothermia during sepsis is largely unknown and thus no effective therapy is available for hypothermia. Therefore, it is important to investigate the mechanism and develop effective therapeutic methods. Lipopolysaccharide (LPS)-induced hypothermia accompanied by excess nitric oxide (NO) production leads to a reduction in energy production in wild-type mice. However, mice lacking inducible nitric oxide synthase did not suffer from LPS-induced hypothermia, suggesting that hypothermia is associated with excess NO production during sepsis. This observation is supported by the treatment of wild-type mice with α-lipoic acid (LA) in that it effectively attenuates LPS-induced hypothermia with decreased NO production. We also found that LA partially restored ATP production, and activities of the mitochondrial enzymes involved in energy metabolism, which were inhibited during sepsis. These data suggest that hypothermia is related to mitochondrial dysfunction, which is probably compromised by excess NO production and that LA administration attenuates hypothermia mainly by protecting mitochondrial enzymes from NO damage.

Mitochondria, endothelial cell function, and vascular diseases

Mitochondria are perhaps the most sophisticated and dynamic responsive sensing systems in eukaryotic cells. The role of mitochondria goes beyond their capacity to create molecular fuel and includes the generation of reactive oxygen species, the regulation of calcium, and the activation of cell death. In endothelial cells, mitochondria have a profound impact on cellular function under both healthy and diseased conditions. In this review, we summarize the basic functions of mitochondria in endothelial cells and discuss the roles of mitochondria in endothelial dysfunction and vascular diseases, including atherosclerosis, diabetic vascular dysfunction, pulmonary artery hypertension, and hypertension. Finally, the potential therapeutic strategies to improve mitochondrial function in endothelial cells and vascular diseases are also discussed, with a focus on mitochondrial-targeted antioxidants and calorie restriction.

Protective effect of Boerhaavia diffusa L. against mitochondrial dysfunction in angiotensin II induced hypertrophy in H9c2 cardiomyoblast cells

Mitochondrial dysfunction plays a critical role in the development of cardiac hypertrophy and heart failure. So mitochondria are emerging as one of the important druggable targets in the management of cardiac hypertrophy and other associated complications. In the present study, effects of ethanolic extract of Boerhaavia diffusa (BDE), a green leafy vegetable against mitochondrial dysfunction in angiotensin II (Ang II) induced hypertrophy in H9c2 cardiomyoblasts was evaluated. H9c2 cells challenged with Ang II exhibited pathological hypertrophic responses and mitochondrial dysfunction which was evident from increment in cell volume (49.09±1.13%), protein content (55.17±1.19%), LDH leakage (58.74±1.87%), increased intracellular ROS production (26.25±0.91%), mitochondrial superoxide generation (65.06±2.27%), alteration in mitochondrial transmembrane potential (ΔΨm), opening of mitochondrial permeability transition pore (mPTP) and mitochondrial swelling. In addition, activities of mitochondrial respiratory chain complexes (I-IV), aconitase, NADPH oxidase, thioredoxin reductase, oxygen consumption rate and calcium homeostasis were evaluated. Treatment with BDE significantly prevented the generation of intracellular ROS and mitochondrial superoxide radicals and protected the mitochondria by preventing dissipation of ΔΨm, opening of mPTP, mitochondrial swelling and enhanced the activities of respiratory chain complexes and oxygen consumption rate in H9c2 cells. Activities of aconitase and thioredoxin reductase which was lowered (33.77±0.68% & 45.81±0.71% respectively) due to hypertrophy, were increased in BDE treated cells (P≤0.05). Moreover, BDE also reduced the intracellular calcium overload in Ang II treated cells. Overall results revealed the protective effects of B. diffusa against mitochondrial dysfunction in hypertrophy in H9c2 cells and the present findings may shed new light on the therapeutic potential of B. diffusa in addition to its nutraceutical potentials.

Testosterone induces apoptosis in vascular smooth muscle cells via extrinsic apoptotic pathway with mitochondria-generated reactive oxygen species involvement

Testosterone exerts both beneficial and harmful effects on the cardiovascular system. Considering that testosterone induces reactive oxygen species (ROS) generation and ROS activate cell death signaling pathways, we tested the hypothesis that testosterone induces apoptosis in vascular smooth muscle cells (VSMCs) via mitochondria-dependent ROS generation. Potential mechanisms were addressed. Cultured VSMCs were stimulated with testosterone (10(-7) mol/l) or vehicle (2-12 h) in the presence of flutamide (10(-5) mol/l), CCCP (10(-6) mol/l), mimetic manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP; 3 × 10(-5) mol/l), Z-Ile-Glu(O-ME)-Thr-Asp(O-Me) fluoromethyl ketone (Z-IETD-FMK; 10(-5) mol/l), or vehicle. ROS were determined with lucigenin and dichlorodihydrofluorescein; apoptosis, with annexin V and calcein; O2 consumption, with a Clark-type electrode, and procaspases, caspases, cytochrome c, Bax, and Bcl-2 levels by immunoblotting. Testosterone induced ROS generation (relative light units/mg protein, 2 h; 162.6 ± 16 vs. 100) and procaspase-3 activation [arbitrary units, (AU), 6 h; 166.2 ± 19 vs. 100]. CCCP, MnTMPyP, and flutamide abolished these effects. Testosterone increased annexin-V fluorescence (AU, 197.6 ± 21.5 vs. 100) and decreased calcein fluorescence (AU, 34.4 ± 6.4 vs. 100), and O2 consumption (nmol O2/min, 18.6 ± 2.0 vs. 34.4 ± 3.9). Testosterone also reduced Bax-to-Bcl-2 ratio but not cytochrome-c release from mitochondria. Moreover, testosterone (6 h) induced cleavage of procaspase 8 (AU, 161.1 ± 13.5 vs. 100) and increased gene expression of Fas ligand (2(ΔΔCt), 3.6 ± 1.2 vs. 0.7 ± 0.5), and TNF-α (1.7 ± 0.4 vs. 0.3 ± 0.1). CCCP, MnTMPyP, and flutamide abolished these effects. These data indicate that testosterone induces apoptosis in VSMCs via the extrinsic apoptotic pathway with the involvement of androgen receptor activation and mitochondria-generated ROS.

Depression-like behaviors in mice subjected to co-treatment of high-fat diet and corticosterone are ameliorated by AICAR and exercise

Major depressive disorder (MDD) and type II diabetes mellitus (T2DM) are highly co-morbid, and there may be a bi-directional connection between the two. Herein, we have described a mouse model of a depression-like and insulin-resistant (DIR) state induced by the co-treatment of high-fat diet (HFD) and corticosterone (CORT). 5-Aminoimidazole-4-carboxamide-1-β-d- ribofuranoside (AICAR), a pharmacological activator of AMP-activated protein kinase (AMPK), was originally used to improve insulin resistance (IR). Interestingly, our results show a clear potential for AICAR as a putative antidepressant with a chronic action on the DIR mice. In contrast to the traditional antidepressants, AICAR as a promising antidepressant avoids reducing insulin actions of skeletal muscle in the context of long-term HFD. Exercise also produced antidepressant effects. Our data suggest that the effects of AICAR and exercise on DIR may further increase our understanding on the link between depression and diabetes.

Lipopolysaccharide stimulates p62-dependent autophagy-like aggregate clearance in hepatocytes

Impairment of autophagy has been associated with liver injury. TLR4-stimulation by LPS upregulates autophagy in hepatocytes, although the signaling pathways involved remain elusive. The objective of this study was to determine the signaling pathway leading to LPS-stimulated autophagy in hepatocytes. Cell lysates from livers of wild type (WT; C57BL/6) mice given LPS (5 mg/kg-IP) and hepatocytes from WT, TLR4ko, and MyD88ko mice treated with LPS (100 ng/mL) up to 24 h were collected. LC3II, p62/SQSTM1, Nrf2, and beclin1 levels were determined by immunoblot, immunofluorescence, and qPCR. Autophagy-like activation was measured by GFP-LC3-puncta formation and LC3II-expression. Beclin1, Nrf2, p62, MyD88, and TIRAP were knocked-down using siRNA. LC3II-expression increased in both liver and hepatocytes after LPS and was dependent on TLR4. Beclin1 expression did not increase after LPS in hepatocytes and beclin1-knockdown did not affect LC3II levels. In hepatocytes given LPS, expression of p62 increased and p62 colocalized with LC3. p62-knockdown prevented LC3II puncta formation. LPS-induced LC3II/p62-puncta also required MyD88/TIRAP signaling and localization of both Nrf2 and NF κ B transcription factors to the nucleus to upregulate p62-expression. Therefore, TLR4-activation by LPS in hepatocytes induces a p62-mediated, not beclin1-mediated, autophagy-like clearance pathway that is hepatoprotective by clearing aggregate-prone or misfolded proteins from the cytosol and preserving energy homeostasis under stress.

Mitochondrial impairment and oxidative stress in leukocytes after testosterone administration to female-to-male transsexuals

INTRODUCTION

Testosterone undecanoate (T) treatment is common in female-to-male transsexuals (FtMs) but can induce impairment of mitochondrial function and oxidative stress.

AIM

The effect of T treatment on the mitochondrial function and redox state of leukocytes of FtMs subjects was evaluated.

METHODS

This was an observational study conducted in a university hospital. Fifty-seven FtMs were treated with T (1,000 mg) for 12 weeks, after which anthropometric and metabolic parameters and mitochondrial function were evaluated.

MAIN OUTCOME MEASURES

Anthropometric and metabolic parameters were evaluated. Mitochondrial function was studied by assessing mitochondrial oxygen (O2) consumption, membrane potential, reactive oxygen species (ROS) production, glutathione levels (GSH), and the reduced glutathione/oxidized glutathione (GSH)/(GSSG) ratio in polymorphonuclear cells.

RESULTS

T treatment led to mitochondrial impairment in FtMs as a result of a decrease in mitochondria O2 consumption, the membrane potential, GSH levels, and the (GSH)/(GSSG) ratio and an increase in ROS production. Mitochondrial O2 consumption and membrane potential negatively correlated with T levels, which was further confirmed that the T treatment had induced mitochondrial dysfunction. T also produced a significant increase in total testosterone, free androgenic index, and atherogenic index of plasma, and a decrease in sex hormone-binding globulin and high-density lipoprotein cholesterol.

CONCLUSIONS

Treatment of FtMs with T can induce impairment of mitochondrial function and a state of oxidative stress. This effect should be taken into account in order to modulate possible comorbidities in these patients.

Perspectives and potential applications of mitochondria-targeted antioxidants in cardiometabolic diseases and type 2 diabetes

There is abundant evidence to suggest that mitochondrial dysfunction is a main cause of insulin resistance and related cardiometabolic comorbidities. On the other hand, insulin resistance is one of the main characteristics of type 2 diabetes, obesity, and metabolic syndrome. Lipid and glucose metabolism require mitochondria to generate energy, and when O2 consumption is low due to inefficient nutrient oxidation, there is an increase in reactive oxygen species, which can impair different types of molecules, including DNA, lipids, proteins, and carbohydrates, thereby inducing proinflammatory processes. Factors which contribute to mitochondrial dysfunction, such as mitochondrial biogenesis and genetics, can also lead to insulin resistance in different insulin-target tissues, and its association with mitochondrial dysfunction can culminate in the development of cardiovascular diseases. In this context, therapies that improve mitochondrial function may also improve insulin resistance. This review explains mechanisms of mitochondrial function related to the pathological effects of insulin resistance in different tissues. The pathogenesis of cardiometabolic diseases will be explained from a mitochondrial perspective and the potential beneficial effects of mitochondria-targeted antioxidants as a therapy for modulating mitochondrial function in cardiometabolic diseases, especially diabetes, will also be considered.

An association between MPO -463 G/A polymorphism and type 2 diabetes

Myeloperoxidase (MPO) is an enzyme which is a member of the haem-peroxidase superfamily and plays a role in production of reactive oxygen species. The most common polymorphism in the promoter region of MPO gene is -463 G/A. It was shown that carrying the GG genotype means increased activity of the gene approximately 2-3-fold compared to GA and AA genotypes. It was found that hyperglycaemia, modified oxidized proteins and increased advanced glycosylated end products (AGE) are related to oxidative stress in diabetes. Under the hyperglycaemic conditions, production of reactive oxygen radical is elevated in smooth muscle endothelial cells, mesengial and tubular endothelial cells. Especially, elevated lipid oxidation plays an important role in pathogenesis of diabetic complications such as cardiovascular complications. We examined the MPO -463 G/A polymorphism by using the PCR-RFLP method in 145 type 2 diabetic patients and 151 healthy controls. We observed that the AA genotype and A allele were protective variants against type 2 diabetes and the GG genotype was a risk factor for diabetes. While we studied the relationship between genotypes and biochemical parameters, we found that patients with the A allele had decreased serum cholesterol, triglyceride, VLDL levels and body mass index. We suggest that the MPO gene has an important role in pathogenesis of type 2 diabetes because of the increased frequency of GG genotype, which is related to increased activity and oxidant capacity of MPO in the patients.

Sustained high serum malondialdehyde levels are associated with severity and mortality in septic patients

Introduction

There is a hyperoxidative state in sepsis. The objective of this study was to determine serum malondialdehyde (MDA) levels during the first week of follow up, whether such levels are associated with severity during the first week and whether non-surviving patients showed higher MDA levels than survivors during the first week.

Methods

We performed an observational, prospective, multicenter study in six Spanish Intensive Care Units. Serum levels of MDA were measured in 328 patients (215 survivors and 113 non-survivors) with severe sepsis at days one, four and eight of diagnosis, and in 100 healthy controls. The primary endpoint was 30-day mortality and the secondary endpoint was six -month mortality. The association between continuous variables was carried out using Spearman’s rank correlation coefficient. Cox regression analysis was applied to determine the independent contribution of serum MDA levels on the prediction of 30-day and 6-month mortality. Hazard ratio (HR) and 95% confidence intervals (CI) were calculated as measures of the clinical impact of the predictor variables.

Results

We found higher serum MDA in septic patients at day one (p < 0.001), day four (p < 0.001) and day eight (p < 0.001) of diagnosis than in healthy controls. Serum MDA was lower in surviving than non-surviving septic patients at day one (p < 0.001), day four (p < 0.001) and day eight (p < 0.001). Serum MDA levels were positively correlated with lactic acid and SOFA during the first week. Finally, serum MDA levels were associated with 30-day mortality (HR = 1.05; 95% CI = 1.02-1.09; p = 0.005) and six-month mortality (hazard ratio (HR) = 1.05; 95% CI = 1.02-1.09; p = 0.003) after controlling for lactic acid levels, acute physiology and chronic health evaluation (APACHE)-II, diabetes mellitus, bloodstream infection and chronic renal failure.

Conclusions

To our knowledge, this is the largest series providing data on the oxidative state in septic patients to date. The novel finding is that high serum MDA levels sustained throughout the first week of follow up were associated with severity and mortality in septic patients.

Is myeloperoxidase a key component in the ROS-induced vascular damage related to nephropathy in type 2 diabetes?

It is still unclear whether microvascular complications of type 2 diabetes correlate with leukocyte-endothelium interactions and/or myeloperoxidase (MPO) levels. In the present study, we found that serum levels of glucose, the rate of ROS and MPO concentration were higher in type 2 diabetic patients. Patients with nephropathy (39.6%) presented higher MPO levels that correlate positively with the albumin/creatinine ratio (r = 0.59, p<0.05). In addition, nephropatic patients showed increased leukocyte-endothelium interactions due to an undermining of polymorphonuclear leukocytes (PMN) rolling velocity and increased rolling flux and adhesion, which was accompanied by a rise in levels of the proinflammatory cytokine tumour necrosis factor alpha (TNFα) and the adhesion molecule E-selectin. Furthermore, MPO levels were positively correlated with PMN rolling flux (r = 0.855, p < 0.01) and adhesion (r = 0.682, p<0.05). Our results lead to the hypothesis that type 2 diabetes induces oxidative stress and an increase in MPO levels and leukocyte-endothelium interactions, and that these effects correlate with the development of nephropathy.

Bariatric surgery rapidly improves mitochondrial respiration in morbidly obese patients

BACKGROUND

Obesity and its attendant comorbidities are an emerging epidemic. Chronic metabolic inflammation (metainflammation) is thought to precipitate obesity-associated morbidities; however, its mechanistic progression is poorly understood. Moreover, although interventions such as diet, exercise, and bariatric surgery can control body weight, their effects on metainflammation are also poorly understood. Recently, metainflammation and the pathobiology of obesity have been linked to mitochondrial dysfunction. Herein we examined the effects of bariatric surgery on mitochondrial respiration as an index of resolving metainflammation in morbidly obese patients.

METHODS

This institutional review board-approved study involved morbidly obese patients (body mass index > 35 kg/m(2)) undergoing sleeve gastrectomy or Roux-en-Y gastric bypass. Mitochondrial respiration was assessed in peripheral blood monocytes and in skeletal muscle samples before surgery and at 12 weeks after surgery. Patient biometrics, homeostasis model assessment-estimated insulin resistance (HOMA-IR) score, C-reactive protein, and lipid profile were analyzed.

RESULTS

Twenty patients were enrolled and showed an average percent excess body weight loss of 30.3% weight loss at 12 weeks after surgery. Average HOMA-IR score decreased from 3.0 to 1.2 in insulin-resistant patients. C-reactive protein, an index of metainflammation, showed a modest decrease. Lipid profile remained stable. Intriguingly, mitochondrial basal and maximal respiration rates in peripheral blood monocytes increased after surgery. Basal rates of skeletal muscle mitochondrial respiration were unchanged, but the maximal respiration rate trended toward an increase after surgery.

CONCLUSIONS

Cellular and tissue mitochondrial respiration increased in a morbidly obese patient cohort after laparoscopic bariatric surgery. These changes were consistent in patients with postsurgical weight loss. Importantly, no significant changes or improvements occurred in canonical indices used to assess recovery after bariatric surgery over this short time course. Thus, increased mitochondrial respiration may represent a novel biomarker of early improvement and positive outcome after surgery in morbidly obese patients.

Correlation of the oxygen radical activity and antioxidants and severity in critically ill surgical patients - study protocol

BACKGROUND

Surgical patients who require an emergent operation commonly have severe sepsis or septic shock, followed by high morbidity and mortality rates.Despite advances in treatment however, no predictable markers are available. In severe sepsis, many pathophysiologic mechanisms are involved in progression to organ failure, and oxygen free radical and antioxidants are known to contribute to this process. Oxygen free radical and antioxidants contribute to progression of organ failure in severe sepsis. In fact, oxygen radical activity has been reported to be correlated with disease severity and prognosis in patients with severe sepsis or septic shock. Accordingly, we aim to assess the usefulness of oxygen free radical and antioxidant concentrations to predict the disease severity and mortality in a cohort of critically ill surgical patients.

METHODS/DESIGN

This is a prospective observation study including patient demographic characteristics, clinical information, blood sampling/serum oxygen radical activity, serum antioxidant activity, serum antioxidant concentrations (zinc, selenium and glutamate), disease severity scores, outcomes, lengths of stay in intensive care unit, hospital 30-day mortality.

Reduced plasmalogen concentration as a surrogate marker of oxidative stress in elderly septic patients

Severe sepsis is reportedly accompanied by oxidative stress with a depletion of antioxidant defense. We estimated plasmalogen vinyl ether bond (PVEB) levels in blood plasma of 20 elderly patients with initial severe sepsis, serving as a sensitive surrogate marker of oxidative stress, and compared them with standard markers, i.e., Acute Physiology and Chronic Health Evaluation (APACHE) II score, C-reactive protein (CRP), creatinine, white blood cell and platelet counts. Patients were included in the study and then blood samples were taken within 24h of the onset of symptoms of severe sepsis. Twenty sex- and age-matched, healthy individuals were included in the study as controls. We measured plasmalogen-derived hexadecanal dimethyl acetal (16:0 DMA) in isolated phospholipids from EDTA-plasma using gas chromatography. We found a 55% lower concentration of 16:0 DMA, corresponding to lower levels of PVEB in the patients' plasma compared to the controls (0.26±0.15 vs 0.58±0.13g/100g; p<0.001). In all patients' and non-survivors' samples the 16:0 DMA levels correlated negatively with plasma CRP values (RS=-0.48 and RS=-0.70, respectively; p<0.05), but not with APACHE II scores or other markers. The observed lower baseline content of PVEB may indicate oxidative stress contributing to the sequlae of sepsis, but did not correlate with the outcome or the severity of illness. Serial measurements are needed to validate PVEB as a marker in sepsis.

Roles for PI3K/AKT/PTEN Pathway in Cell Signaling of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver pathologies and is associated with obesity and the metabolic syndrome, which represents a range of fatty liver diseases associated with an increased risk of type 2 diabetes. Molecular mechanisms underlying how to make transition from simple fatty liver to nonalcoholic steatohepatitis (NASH) are not well understood. However, accumulating evidence indicates that deregulation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway in hepatocytes is a common molecular event associated with metabolic dysfunctions including obesity, metabolic syndrome, and the NAFLD. A tumor suppressor PTEN negatively regulates the PI3K/AKT pathways through its lipid phosphatase activity. Molecular studies in the NAFLD support a key role for PTEN in hepatic insulin sensitivity and the development of steatosis, steatohepatitis, and fibrosis. We review recent studies on the features of the PTEN and the PI3K/AKT pathway and discuss the protein functions in the signaling pathways involved in the NAFLD. The molecular mechanisms contributing to the diseases are the subject of considerable investigation, as a better understanding of the pathogenesis will lead to novel therapies for a condition.