Alveolar Mitochondrial Quality Control During Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) is a leading cause of respiratory failure and death in patients in the intensive care unit. Experimentally, acute lung injury resolution depends on the repair of mitochondrial oxidant damage by the mitochondrial quality control (MQC) pathways, mitochondrial biogenesis, and mitophagy, but nothing is known about this in the human lung. In a case-control autopsy study, we compared the lungs of subjects dying of ARDS (n = 8; cases) and age-/gender-matched subjects dying of nonpulmonary causes (n = 7; controls). Slides were examined by light microscopy and immunofluorescence confocal microscopy, randomly probing for co-localization of citrate synthase with markers of oxidant stress, mitochondrial DNA damage, mitophagy, and mitochondrial biogenesis. ARDS lungs showed diffuse alveolar damage with edema, hyaline membranes, and neutrophils. Compared with controls, a high degree of mitochondrial oxidant damage was seen in type 2 epithelial (AT2) cells and alveolar macrophages by 8-hydroxydeoxyguanosine and malondialdehyde co-staining with citrate synthase. In ARDS, antioxidant protein heme oxygenase-1 and DNA repair enzyme N-glycosylase/DNA lyase (Ogg1) were found in alveolar macrophages but not in AT2 cells. Moreover, MAP1 light chain-3 (LC3) and serine/threonine-protein kinase (Pink1) staining were absent in AT2 cells, suggesting a mitophagy failure. Nuclear respiratory factor-1 staining was missing in the alveolar region, suggesting impaired mitochondrial biogenesis. Widespread hyperproliferation of AT2 cells in ARDS could suggest defective differentiation into type 1 cells. ARDS lungs show profuse mitochondrial oxidant DNA damage but little evidence of MQC activity in AT2 epithelium. Because these pathways are important for acute lung injury resolution, our findings support MQC as a novel pharmacologic target for ARDS resolution.

The Molecular Context of Oxidant Stress Response in Cancer Establishes ALDH1A1 as a Critical Target: What This Means for Acute Myeloid Leukemia.

The protein family of aldehyde dehydrogenases (ALDH) encompasses nineteen members. The ALDH1 subfamily consists of enzymes with similar activity, having the capacity to neutralize lipid peroxidation products and to generate retinoic acid; however, only ALDH1A1 emerges as a significant risk factor in acute myeloid leukemia. Not only is the gene ALDH1A1 on average significantly overexpressed in the poor prognosis group at the RNA level, but its protein product, ALDH1A1 protects acute myeloid leukemia cells from lipid peroxidation byproducts. This capacity to protect cells can be ascribed to the stability of the enzyme under conditions of oxidant stress. The capacity to protect cells is evident both in vitro, as well as in mouse xenografts of those cells, shielding cells effectively from a number of potent antineoplastic agents. However, the role of ALDH1A1 in acute myeloid leukemia has been unclear in the past due to evidence that normal cells often have higher aldehyde dehydrogenase activity than leukemic cells. This being true, ALDH1A1 RNA expression is significantly associated with poor prognosis. It is hence imperative that ALDH1A1 is methodically targeted, particularly for the acute myeloid leukemia patients of the poor prognosis risk group that overexpress ALDH1A1 RNA.

[Regulative effects of endogenous sulfur dioxide on oxidant stress in myocardium of rat with sepsis].

OBJECTIVE: To explore the modulating effect of endogenous sulfur dioxide (SO2) on the ba-lance of oxidation/reduction in the cecal-ligation-and-puncture-induced septic rat myocardium. METHODS: Forty male Sprague Dawley rats were randomized into control group, SO2group, sepsis group and sepsis + SO2group. The levels of procalcitonin (PCT), creatine kinase isoenzyme (CK-MB), cardiac troponin Ⅰ (cTn Ⅰ) and fatty acid binding protein (FABP) in plasma in each group of the rats were measured; The level of hydrogen peroxide (H2O2), level of nitric oxide (NO), activity of myeloperoxidase (MPO), activity of hydroxyl free radical (·OH) and level of malondialdehyde (MDA) in myocardial tissue were measured; Total antioxidant capacity (T-AOC), activity of catalase (CAT), level of cytochrome oxidase (CO), level of glutathione (GSH), level of glutathione oxidase (GSH-px) and activity of superoxide dismutase (SOD) in myocardial tissue were measured. RESULTS: The level of PCT in plasma in the rats with sepsis increased from (0.93±0.26) µg/L to (2.45±0.52) µg/L (P < 0.01), and decreased to (1.58±0.36) µg/L after the intervention of sulfur dioxide donor (P < 0.01). In sepsis, the plasma CK-MB, cTn Ⅰ and FABP levels in the rats increased respectively from (14.46±6.48) µg/L, (151.25±30.14) ng/L and (2.72±0.65) µg/L to (23.72±7.72) µg/L, (272.78±52.70) ng/L and (5.22±1.01) µg/L (P all < 0.01), and decreased to (16.74±3.63) µg/L, (184.86±37.72) µg/L and (3.31±0.84) µg/L (all P < 0.05) after the intervention of sulfur dioxide donor. The level of H2O2, level of NO, activity of MPO, activity of ·OH and level of MDA in myocardial tissue in the rats with sepsis increased respectively from (67.26±8.77) mmol/g, (38.39±6.93) µmol/g, (358.25±68.12) U/g, (648.42±93.69) U/ mg and (4.55±0.96) µmol/g to (111.45±17.35) mmol/g, (51.04±5.91) µmol/g, (465.88±76.76) U/g, (873.75±123.47) U/mg and (7.25±0.86) µmol/g (all P < 0.01), and decreased respectively to (75.99±10.52) mmol/g, (39.39±7.80) µmol/g, (393.17±51.5) U/g, (710.54±106.33) U/mg and (5.16±0.65) µmol/g after the intervention of the sulfur dioxide donor (all P < 0.05). The activity of T-AOC, activity of CAT, level of CO, level of GSH, level of GSH-px and activity of SOD in myocardial tissue in the rats with sepsis increased respectively from (2.07±0.37) U/mg, (169.25±36.86) U/g, (1.35±0.32) µmol/g, (103.51±16.62) µmol/g, (38.40±7.97) µmol/g and (38.50±8.30) U/mg to (1.42±0.39) U/mg, (98.44±26.56) U/g, (0.96±0.21) µmol/g, (68.05±7.35) µmol/ g, (23.83±5.04) µmol/g and (23.11±4.63) U/mg (P all < 0.01), and increased respectively to (1.83±0.37) U/mg, (146.14±31.63) U/g, (1.28±0.20) µmol/g, (92.10±11.84) µmol/g, (37.16±3.01) µmol/g and (37.29±2.62) U/mg (P all < 0.05) after the intervention of the sulfur dioxide donor. CONCLUSION: Endogenous SO2 can protect rat myocardium in sepsis by modulating the ba-lance of oxidation and reduction.

Small molecule compound M12 reduces vascular permeability in obese mice via blocking endothelial TRPV4-Nox2 interaction.

Transient receptor potential channel TRPV4 and nicotinamide adenine dinucleotide phosphate oxidase (Nox2) are involved in oxidative stress that increases endothelial permeability. It has been shown that obesity enhances the physical association of TRPV4 and Nox2, but the role of TRPV4-Nox2 association in obesity has not been clarified. In this study we investigated the function of TRPV4-Nox2 complex in reducing oxidative stress and regulating abnormal vascular permeability in obesity. Obesity was induced in mice by feeding a high-fat diet (HFD) for 14 weeks. The physical interaction between TRPV4 and Nox2 was measured using FRET, co-immunoprecipitation and GST pull-down assays. The functional interaction was measured by rhodamine phalloidin, CM-H2DCFDA in vitro, the fluorescent dye dihydroethidium (DHE) staining assay, and the Evans blue permeability assay in vivo. We demonstrated that TRPV4 physically and functionally associated with Nox2, and this physical association was enhanced in aorta of obese mice. Furthermore, we showed that interrupting TRPV4-Nox2 coupling by TRPV4 knockout, or by treatment with a specific Nox2 inhibitor Nox2 dstat or a specific TRPV4 inhibitor HC067046 significantly attenuated obesity-induced ROS overproduction in aortic endothelial cells, and reversed the abnormal endothelial cytoskeletal structure. In order to discover small molecules disrupting the over-coupling of TPRV4 and Nox2 in obesity, we performed molecular docking analysis and found that compound M12 modulated TRPV4-Nox2 association, reduced ROS production, and finally reversed disruption of the vascular barrier in obesity. Together, this study, for the first time, provides evidence for the TRPV4 physically interacting with Nox2. TRPV4-Nox2 complex is a potential drug target in improving oxidative stress and disruption of the vascular barrier in obesity. Compound M12 targeting TRPV4-Nox2 complex can improve vascular barrier function in obesity.

Low serum uric acid levels are associated with incidence and severity in trigeminal neuralgia.

BACKGROUND: Uric acid is a natural antioxidant, and low levels of uric acid have been reported to be a potential risk factor in the development of nervous system diseases. Herein, we investigated whether uric acid levels play a role in trigeminal neuralgia (TN). METHODS: We conducted a cohort study to compare the serum uric acid levels of patients with TN and healthy controls. We also analyzed the impact of uric acid levels on the risk of TN and symptom severity. RESULTS: In comparison to control participants (n = 133), uric acid levels were remarkably decreased in patients with TN (n = 181). Uric acid (OR = 0.989; 95% CI 0.986-0.993; P < 0.001) was also determined as a protective factor against TN based on multivariate logistic regression models. Furthermore, nonlinear relationships between serum uric acid levels and TN incidence rate and between that and the Barrow Neurological Institute (BNI) grading were observed. CONCLUSIONS: Our study is the first to show a relationship between serum uric acid levels and TN. Specifically, low serum uric acid levels were associated with an increased risk of TN and more severe clinical symptoms. We expect that these findings will provide new insights into the prevention and treatment of TN.

Association of LTA and SOD Gene Polymorphisms with Cerebral White Matter Hyperintensities in Migraine Patients.

White matter hyperintensities (WMHs) in migraine could be related to inflammatory and antioxidant events. The aim of this study is to verify whether migraine patients with WMHs carry a genetic pro-inflammatory/pro-oxidative status. To test this hypothesis, we analyzed lymphotoxin alpha (LTA; rs2071590T and rs2844482G) and superoxide dismutase 1 (SOD1; rs2234694C) and 2 (SOD2; rs4880T) gene polymorphisms (SNPs) in 370 consecutive patients affected by episodic (EM; n = 251) and chronic (CM; n = 119) migraine and in unrelated healthy controls (n = 100). Brain magnetic resonance was available in 183/370 patients. The results obtained show that genotypes and allele frequencies for all tested SNPs did not differ between patients and controls. No association was found between single SNPs or haplotypes and sex, migraine type, cardiovascular risk factors or disorders. Conversely, the LTA rs2071590T (OR = 2.2) and the SOD1 rs2234694C (OR = 4.9) alleles were both associated with WMHs. A four-loci haplotype (TGCT haplotype: rs2071590T/rs2844482G/rs2234694C/rs4880T) was significantly more frequent in migraineurs with WMHs (7 of 38) compared to those without WMHs (4 of 134; OR = 8.7). We may, therefore, conclude by suggesting that that an imbalance between pro-inflammatory/pro-oxidative and antioxidant events in genetically predisposed individuals may influence the development of WMHs.

Effects of Apamin on MPP+-Induced Calcium Overload and Neurotoxicity by Targeting CaMKII/ERK/p65/STAT3 Signaling Pathways in Dopaminergic Neuronal Cells.

Parkinson's disease (PD), a neurodegenerative disorder, is characterized by the loss of dopaminergic (DA) neurons. The pathogenesis of PD is associated with several factors including oxidative stress, inflammation, and mitochondrial dysfunction. Ca2+ signaling plays a vital role in neuronal signaling and altered Ca2+ homeostasis has been implicated in many neuronal diseases including PD. Recently, we reported that apamin (APM), a selective antagonist of the small-conductivity Ca2+-activated K+ (SK) channel, suppresses neuroinflammatory response. However, the mechanism(s) underlying the vulnerability of DA neurons were not fully understood. In this study, we investigated whether APM affected 1-methyl-4-phenyl pyridinium (MPP+)-mediated neurotoxicity in SH-SY5Y cells and rat embryo primary mesencephalic neurons. We found that APM decreased Ca2+ overload arising from MPP+-induced neurotoxicity response through downregulating the level of CaMKII, phosphorylation of ERK, and translocation of nuclear factor NFκB/signal transducer and activator of transcription (STAT)3. Furthermore, we showed that the correlation of MPP+-mediated Ca2+ overload and ERK/NFκB/STAT3 in the neurotoxicity responses, and dopaminergic neuronal cells loss, was verified through inhibitors. Our findings showed that APM might prevent loss of DA neurons via inhibition of Ca2+-overload-mediated signaling pathway and provide insights regarding the potential use of APM in treating neurodegenerative diseases.

ß1-adrenergic receptor N-terminal cleavage by ADAM17; the mechanism for redox-dependent downregulation of cardiomyocyte ß1-adrenergic receptors.

ß1-adrenergic receptors (ß1ARs) are the principle mediators of catecholamine action in cardiomyocytes. We previously showed that the ß1AR extracellular N-terminus is a target for post-translational modifications that impact on signaling responses. Specifically, we showed that the ß1AR N-terminus carries O-glycan modifications at Ser37/Ser41, that O-glycosylation prevents ß1AR N-terminal cleavage, and that N-terminal truncation influences ß1AR signaling to downstream effectors. However, the site(s) and mechanism for ß1AR N-terminal cleavage in cells was not identified. This study shows that ß1ARs are expressed in cardiomyocytes and other cells types as both full-length and N-terminally truncated species and that the truncated ß1AR species is formed as a result of an O-glycan regulated N-terminal cleavage by ADAM17 at R31↓L32. We identify Ser41 as the major O-glycosylation site on the ß1AR N-terminus and show that an O-glycan modification at Ser41 prevents ADAM17-dependent cleavage of the ß1-AR N-terminus at S41↓L42, a second N-terminal cleavage site adjacent to this O-glycan modification (and it attenuates ß1-AR N-terminal cleavage at R31↓L32). We previously reported that oxidative stress leads to a decrease in ß1AR expression and catecholamine responsiveness in cardiomyocytes. This study shows that redox-inactivation of cardiomyocyte ß1ARs is via a mechanism involving N-terminal truncation at R31↓L32 by ADAM17. In keeping with the previous observation that N-terminally truncated ß1ARs constitutively activate an AKT pathway that affords protection against doxorubicin-dependent apoptosis, overexpression of a cleavage resistant ß1AR mutant exacerbates doxorubicin-dependent apoptosis. These studies identify the ß1AR N-terminus as a structural determinant of ß1AR responses that can be targeted for therapeutic advantage.

Fatty acid desaturase activity in mature red blood cells and implications for blood storage quality.

BACKGROUND: Increases in the red blood cell (RBC) degree of fatty acid desaturation are reported in response to exercise, aging, or diseases associated with systemic oxidant stress. However, no studies have focused on the presence and activity of fatty acid desaturases (FADS) in the mature RBC. STUDY DESIGN AND METHODS: Steady state metabolomics and isotope-labeled tracing experiments, immunofluorescence approaches, and pharmacological interventions were used to determine the degree of fatty acid unsaturation, FADS activity as a function of storage, oxidant stress, and G6PD deficiency in human and mouse RBCs. RESULTS: In 250 blood units from the REDS III RBC Omics recalled donor population, we report a storage-dependent accumulation of free mono-, poly-(PUFAs), and highly unsaturated fatty acids (HUFAs), which occur at a faster rate than saturated fatty acid accumulation. Through a combination of immunofluorescence, pharmacological inhibition, tracing experiments with stable isotope-labeled fatty acids, and oxidant challenge with hydrogen peroxide, we demonstrate the presence and redox-sensitive activity of FADS2, FADS1, and FADS5 in the mature RBC. Increases in PUFAs and HUFAs in human and mouse RBCs correlate negatively with storage hemolysis and positively with posttransfusion recovery. Inhibition of these enzymes decreases accumulation of free PUFAs and HUFAs in stored RBCs, concomitant to increases in pyruvate/lactate ratios. Alterations of this ratio in G6PD deficient patients or units supplemented with pyruvate-rich rejuvenation solutions corresponded to decreased PUFA and HUFA accumulation. CONCLUSION: Fatty acid desaturases are present and active in mature RBCs. Their activity is sensitive to oxidant stress, storage duration, and alterations of the pyruvate/lactate ratio.

Radioprotective effect of radiation-induced Lactococcus lactis cell-free extract against 60Coγ injury in mice.

Ionizing radiation (IR) is widely used in the diagnosis and treatment of various cancers. However, IR can cause damage to human health by producing reactive oxygen species. Lactococcus lactis is a type of microorganism that is beneficial to human health and has a strong antioxidant capacity. In this study, the protective effect of normal and IR-induced L. lactis IL1403 cell-free extracts (CFE and IR-CFE, respectively) against oxidative damage in vitro and the radioprotective effect of IR-CFE in vivo was evaluated using 60Coγ-induced oxidative damage model in mice. Results showed that IR-CFE exhibited a stronger oxidative damage-protective effect than CFE for L. lactis IL1403 under H2O2 in vitro. Moreover, IR-CFE also showed strong radioprotective effect on hepatocyte cells (AML-12) under radiation condition, and the effect was better than that of CFE. Animal experiment indicated that IR-CFE could reduce the IR-induced damage to the hematopoietic system by increasing the number of white blood cells and red blood cells in peripheral blood of irradiated mice. It was also observed that IR-CFE could markedly alleviate the 60Coγ-induced oxidative stress via increasing the activities of superoxide dismutase and glutathione peroxidase, enhancing the levels of glutathione, and decreasing the contents of malondialdehyde in serum, liver, and spleen. In addition, IR-CFE also could reduce the activities of alanine transaminase and aspartate aminotransferase in serum, thereby reducing radiation damage to the liver. These results suggested that IR-CFE could be considered as potential candidates for natural radioprotective agents. This study provides a theoretical basis for improving the application of lactic acid bacteria.

Toxic effects of TiO2 NPs in the blood-milk barrier of the maternal dams and growth of offspring.

Titanium dioxide nanoparticles (TiO2 NPs) are amongst the most frequently used nanomaterial in everyday consumer products, and their widespread applications have raised concerns of the consequent deleterious effects on human health, particularly to vulnerable populations, such as lactating females remains elusive. Therefore, this study was initiated to investigate the detrimental effects and toxic mechanisms induced by TiO2 NPs in maternal dams and offspring during the lactation period. Dams were randomly divided into three groups. The water (Control; Group I) and TiO2 NPs (100 mg/kg; Group II) were orally administered from postnatal day 1-20, respectively. The results indicated that TiO2 NPs could cause toxicity in the dams, such as pathological damages to mammary gland tissues. The excessive accumulation of TiO2 NPs could induce oxidative stress in the mammary gland, leading to the dysfunctional blood-milk barrier; besides, TiO2 NPs could also be transferred to offspring via breastfeeding, causing abnormal development of infant. We further accessed the possible underlying molecular mechanism; for this, we orally administered TiO2 NPs with vitamin E (100 mg/kg; Group III). The results revealed that toxicity induced by TiO2 NPs was rescued. Collectively, this study presented the deleterious pathological effects of oral exposure to TiO2 NPs in the mammary gland tissues and blood-milk barrier via the production of reactive oxygen species (ROS) in dams and developmental concerns in offspring. However, the administration of VE could mitigate the toxic effects induced by the TiO2 NPs.

Rapamycin attenuates the paraquat-induced pulmonary fibrosis through activating Nrf2 pathway.

Oxidative stress is a key regulator of idiopathic pulmonary fibrosis. Paraquat (PQ)-induced pulmonary fibrosis seriously endangers people's health. Rapamycin has been reported to alleviate PQ-induced pulmonary fibrosis, but its underlying mechanism is unclear. The nuclear factor E2-related factor 2 (Nrf2) plays an important regulatory role in the antioxidant therapy of PQ-induced pulmonary fibrosis. In this study, we tried to confirm that rapamycin attenuates PQ-induced pulmonary fibrosis by regulating Nrf2 pathway. In vivo, we proved that rapamycin could inhibit the degree of PQ-induced oxidant stress as well as enhanced the expression of Nrf2. In vitro, rapamycin decreased the upregulated effects of cell death and apoptosis, fibrosis-related factors expression and fibroblast-to-myofibroblast transformation by PQ treatment. In vivo, rapamycin treatment reduced fibrosis degree and the expression of fibrosis-related factors in lung tissues of rat treated PQ. Furthermore, we also found that Nrf2 knockdown reduced the inhibitory effect of rapamycin on PQ-induced pulmonary fibrosis, as well as decreased Nrf2 transfer from the cytoplasm into the nucleus. Our findings demonstrated that the protective effect of rapamycin is associated with the activation of the Nrf2 pathway in pulmonary fibrosis induced by PQ poisoning.

Mice deficient in pyruvate dehydrogenase kinase 4 are protected against acetaminophen-induced hepatotoxicity.

Though mitochondrial oxidant stress plays a critical role in the progression of acetaminophen (APAP) overdose-induced liver damage, the influence of mitochondrial bioenergetics on this is not well characterized. This is important, since lifestyle and diet alter hepatic mitochondrial bioenergetics and an understanding of its effects on APAP-induced liver injury is clinically relevant. Pyruvate dehydrogenase (PDH) is critical to mitochondrial bioenergetics, since it controls the rate of generation of reducing equivalents driving respiration, and pyruvate dehydrogenase kinase 4 (PDK4) regulates (inhibits) PDH by phosphorylation. We examined APAP-induced liver injury in PDK4-deficient (PDK4-/-) mice, which would have constitutively active PDH and hence elevated flux through the mitochondrial electron transport chain. PDK4-/- mice showed significant protection against APAP-induced liver injury when compared to wild type (WT) mice as measured by ALT levels and histology. Deficiency of PDK4 did not alter APAP metabolism, with similar APAP-adduct levels in PDK4-/- and WT mice, and no difference in JNK activation and translocation to mitochondria. However, subsequent amplification of mitochondrial dysfunction with release of mitochondrial AIF, peroxynitrite formation and DNA fragmentation were prevented. Interestingly, APAP induced a rapid decline in UCP2 protein levels in PDK4-deficient mice. These data suggest that adaptive changes in mitochondrial bioenergetics induced by enhanced respiratory chain flux in PDK4-/- mice render them highly efficient in handling APAP-induced oxidant stress, probably through modulation of UCP2 levels. Further investigation of these specific adaptive mechanisms would provide better insight into the control exerted by mitochondrial bioenergetics on cellular responses to an APAP overdose.

Calcium Signaling and Reactive Oxygen Species in Mitochondria.

In heart failure, alterations of Na+ and Ca2+ handling, energetic deficit, and oxidative stress in cardiac myocytes are important pathophysiological hallmarks. Mitochondria are central to these processes because they are the main source for ATP, but also reactive oxygen species (ROS), and their function is critically controlled by Ca2+ During physiological variations of workload, mitochondrial Ca2+ uptake is required to match energy supply to demand but also to keep the antioxidative capacity in a reduced state to prevent excessive emission of ROS. Mitochondria take up Ca2+ via the mitochondrial Ca2+ uniporter, which exists in a multiprotein complex whose molecular components were identified only recently. In heart failure, deterioration of cytosolic Ca2+ and Na+ handling hampers mitochondrial Ca2+ uptake and the ensuing Krebs cycle-induced regeneration of the reduced forms of NADH (nicotinamide adenine dinucleotide) and NADPH (nicotinamide adenine dinucleotide phosphate), giving rise to energetic deficit and oxidative stress. ROS emission from mitochondria can trigger further ROS release from neighboring mitochondria termed ROS-induced ROS release, and cross talk between different ROS sources provides a spatially confined cellular network of redox signaling. Although low levels of ROS may serve physiological roles, higher levels interfere with excitation-contraction coupling, induce maladaptive cardiac remodeling through redox-sensitive kinases, and cell death through mitochondrial permeability transition. Targeting the dysregulated interplay between excitation-contraction coupling and mitochondrial energetics may ameliorate the progression of heart failure.

The Role of the Nrf2 Signaling in Obesity and Insulin Resistance.

Obesity, a metabolic disorder characterized by excessive accumulation of adipose tissue, has globally become an increasingly prevalent disease. Extensive studies have been conducted to elucidate the underlying mechanism of the development of obesity. In particular, the close association of inflammation and oxidative stress with obesity has become increasingly evident. Obesity has been shown to exhibit augmented levels of circulating proinflammatory cytokines, which have been associated with the activation of pathways linked with inflammation-induced insulin resistance, a major pathological component of obesity and several other metabolic disorders. Oxidative stress, in addition to its role in stimulating adipose differentiation, which directly triggers obesity, is considered to feed into this pathway, further aggravating insulin resistance. Nuclear factor E2 related factor 2 (Nrf2) is a basic leucine zipper transcription factor that is activated in response to inflammation and oxidative stress, and responds by increasing antioxidant transcription levels. Therefore, Nrf2 has emerged as a critical new target for combating insulin resistance and subsequently, obesity. However, the effects of Nrf2 on insulin resistance and obesity are controversial. This review focuses on the current state of research on the interplay of inflammation and oxidative stress in obesity, the role of the Nrf2 pathway in obesity and insulin resistance, and the potential use of Nrf2 activators for the treatment of insulin resistance.

Thiol-disulfide homeostasis: an integrated approach with biochemical and clinical aspects

Dynamic thiol-disulfide homeostasis (TDH) is a new area has begun to attract more scrutiny. Dynamic TDH is reversal of thiol oxidation in proteins and represents the status of thiols (-SH) and disulfides (-S-S-). Organic compounds containing the sulfhydryl group is called thiol, composed of sulfur and hydrogen atoms. Disulfides are the most important class of dynamic, redox responsive covalent bonds build in between two thiol groups. For many years, thiol levels were analyzed by several methods. During last years, measurements of disulfide levels have been analyzed by a novel automated method, developed by Erel and Neselioglu. In this method, addition to thiol (termed as native thiol) levels, disulfide levels were also measured and sum of native thiol and disulfide levels were termed as total thiol. Therefore, TDH was begun to be understood in organism. In healthy humans, TDH is maintained within a certain range. Dysregulated dynamic TDH has been implicated several disorders with unknown etiology. A growing body of evidence has demonstrated that the thiol-disulfide homeostasis is involved in variety diseases, such as diabetes mellitus, hypertension, nonsmall cell lung cancer, familial Mediterranean fever (FMF), inflammatory bowel diseases, occupational diseases, gestational diabetes mellitus and preeclampsia. These results may elucidate some pathogenic mechanism or may be a predictor indicating diagnostic clue, prognostic marker or therapeutic sign. In conclusion, protection of the thiol-disulfide homeostasis is of great importance for the human being. Evidence achieved so far has proposed that thiol-disulfide homeostasis is an important issue needs to elucidate wholly.

Deficiency of nuclear receptor interaction protein leads to cardiomyopathy by disrupting sarcomere structure and mitochondrial respiration.

BACKGROUND: Cardiomyopathy is a common and lethal complication in patients with limb-girdle muscular dystrophy (LGMD), one of the most prevalent forms of muscular dystrophy. The pathogenesis underlying LGMD-related cardiomyopathy remains unclear. NRIP (gene name DCAF6), a Ca2+-dependent calmodulin binding protein, was reduced in dystrophic muscles from LGMD patients. Mice lacking NRIP exhibit a myopathic phenotype resembling that in LGMD patients, making NRIP deficiency a potential culprit leading to cardiomyopathy. This study aimed to determine if NRIP deficiency leads to cardiomyopathy and to explore the underlying molecular mechanisms. METHODS AND RESULTS: NRIP expression was reduced in both human and mouse failing hearts. Muscle-specific NRIP knockout (MCK-Cre::Dcaf6flox/flox) mouse heart and isolated cardiomyocytes exhibited markedly reduced contractility. Transmission electron microscopy revealed abnormal sarcomere structures and mitochondrial morphology in MCK-Cre::Dcaf6flox/flox hearts. Protein co-immunoprecipitation and confocal imaging revealed that NRIP interacts with α-actinin 2 (ACTN2) at the Z-disc. We found that NRIP facilitated ACTN2-mediated F-actin bundling, and that NRIP deficiency resulted in reduced binding between Z-disc proteins ACTN2 and Cap-Z. In addition, NRIP-deficiency led to increased mitochondrial ROS and impaired mitochondrial respiration/ATP production owing to elevated cellular NADH/NAD+ ratios. Treatment with mitochondria-directed antioxidant mitoTEMPO or NAD+ precursor nicotinic acid restored mitochondrial function and cardiac contractility in MCK-Cre::Dcaf6flox/flox mice. CONCLUSIONS: NRIP is essential to maintain sarcomere structure and mitochondrial/contractile function in cardiomyocytes. Our results revealed a novel role for NRIP deficiency in the pathogenesis of LGMD and heart failure. Targeting NRIP, therefore, could be a powerful new approach to treat myocardial dysfunction in LGMD and heart failure patients.

Vascular TSP1-CD47 signaling promotes sickle cell-associated arterial vasculopathy and pulmonary hypertension in mice.

Pulmonary hypertension (PH) is a leading cause of death in sickle cell disease (SCD) patients. Hemolysis and oxidative stress contribute to SCD-associated PH. We have reported that the protein thrombospondin-1 (TSP1) is elevated in the plasma of patients with SCD and, by interacting with its receptor CD47, limits vasodilation of distal pulmonary arteries ex vivo. We hypothesized that the TSP1-CD47 interaction may promote PH in SCD. We found that TSP1 and CD47 are upregulated in the lungs of Berkeley (BERK) sickling (Sickle) mice and patients with SCD-associated PH. We then generated chimeric animals by transplanting BERK bone marrow into C57BL/6J (n = 24) and CD47 knockout (CD47KO, n = 27) mice. Right ventricular (RV) pressure was lower in fully engrafted Sickle-to-CD47KO than Sickle-to-C57BL/6J chimeras, as shown by the reduced maximum RV pressure (P = 0.013) and mean pulmonary artery pressure (P = 0.020). The afterload of the sickle-to-CD47KO chimeras was also lower, as shown by the diminished pulmonary vascular resistance (P = 0.024) and RV effective arterial elastance (P = 0.052). On myography, aortic segments from Sickle-to-CD47KO chimeras showed improved relaxation to acetylcholine. We hypothesized that, in SCD, TSP1-CD47 signaling promotes PH, in part, by increasing reactive oxygen species (ROS) generation. In human pulmonary artery endothelial cells, treatment with TSP1 stimulated ROS generation, which was abrogated by CD47 blockade. Explanted lungs of CD47KO chimeras had less vascular congestion and a smaller oxidative footprint. Our results show that genetic absence of CD47 ameliorates SCD-associated PH, which may be due to decreased ROS levels. Modulation of TSP1-CD47 may provide a new molecular approach to the treatment of SCD-associated PH.

Ethanol withdrawal mitigates fatty liver by normalizing lipid catabolism.

We are investigating the changes in hepatic lipid catabolism that contribute to alcohol-induced fatty liver. Following chronic ethanol (EtOH) exposure, abstinence from alcohol resolves steatosis. Here, we investigated the hepatocellular events that lead to this resolution by quantifying specific catabolic parameters that returned to control levels after EtOH was withdrawn. We hypothesized that, after its chronic consumption, EtOH withdrawal reactivates lipid catabolic processes that restore lipostasis. Male Wistar rats were fed control and EtOH liquid diets for 6 wk. Randomly chosen EtOH-fed rats were then fed control diet for 7 days. Liver triglycerides (TG), lipid peroxides, key markers of fatty acid (FA) metabolism, lipophagy, and autophagy were quantified. Compared with controls, EtOH-fed rats had higher hepatic triglycerides, lipid peroxides, and serum free fatty acids (FFA). The latter findings were associated with higher levels of FA transporters (FATP 2, 4, and 5) but lower quantities of peroxisome proliferator-activated receptor-α (PPAR-α), which governs FA oxidation. EtOH-fed animals also had lower nuclear levels of the autophagy-regulating transcription factor EB (TFEB), associated with lower hepatic lipophagy and autophagy. After EtOH-fed rats were refed control diet for 7 days, their serum FFA levels and those of FATPs fell to control (normal) levels, whereas PPAR-α levels rose to normal. Hepatic TG and malondialdehyde levels in EtOH-withdrawn rats declined to near control levels. EtOH withdrawal restored nuclear TFEB content, hepatic lipophagy, and autophagy activity to control levels. EtOH withdrawal reversed aberrant FA metabolism and restored lysosomal function to promote resolution of alcohol-induced fatty liver. NEW & NOTEWORTHY Here, using an animal model, we show mechanisms of reversal of fatty liver and injury following EtOH withdrawal. Our data indicate that reactivation of autophagy and lysosome function through the restoration of transcription factor EB contribute to reversal of fatty liver and injury following EtOH withdrawal.

Melatonin prevents bone destruction in mice with retinoic acid-induced osteoporosis.

BACKGROUND: The protective effect of melatonin against bone metabolism imbalance in osteoporosis (OP) induced by drugs such as retinoic acid (RA) is unclear. The aim of this study was to explore the role of melatonin in bone destruction based on a mouse model. METHODS: RA-induced OP model mice were established. To assess the effect of melatonin on these mice, micro-CT was used to characterize the trabecular structure of normal mice and those treated with RA (model), RA + low-dose melatonin (Mlt-L), RA + high-dose melatonin (Mlt-H), and RA + alendronate sodium (positive control). The shape of the trabecular bone, the length and diameter of the femoral head and the height and diameter of vertebra(L1) of each group were also measured and the number of osteoclasts was determined by Tartrate-resistant acid phosphatase (TRACP) staining. Meanwhile, the expression of alkaline phosphatase (ALP) was evaluated by immunohistochemistry assays. The differences between groups in terms of liver and kidney oxidation-related indexes and serum and urinary indicators related to bone metabolism were also analyzed. Furthermore, qRT-PCR and western blotting were used to evaluate the effect of melatonin on osteogenic and osteoclastic differentiation in MC3T3-E1 and RAW264.7 cells, respectively. RESULTS: RA induction led to a decrease in the amount and density of trabecular bone, a decrease in the length and diameter of the femur and height, diameter of the vertebra (L1), a decrease in bone mass and density and the expression of ALP, and an increase in the number of osteoclasts. Melatonin treatment alleviated these effects induced by RA, increasing the amount of trabecular bone in OP mice, improving the microstructure of the femur and vertebra(L1) and increasing bone mass bone density and the expression of ALP, as well as decreasing the number of osteoclasts. Additionally, blood and urinary bone metabolism-related indicators showed that melatonin promoted bone formation and inhibited bone resorption. Determination of oxidant and antioxidant biomarkers in the livers and kidneys of the mice revealed that melatonin promoted the antioxidant level and suppressed the level of oxidant molecules in these organs. In vitro, RA promoted osteoclasts and inhibit osteogenesis by increasing oxidative stress levels in the RAW264.7 and MC3T3-E1 cells, but melatonin reversed this effect. Melatonin may, therefore, play a role in the ERK/SMAD and NF-κB pathways. CONCLUSIONS: Melatonin can alleviate bone loss in RA-induced OP model mice, repair the trabecular microstructure, and promote bone formation. These effects may be related to reducing oxidation levels in vivo and vitro through the ERK/SMAD and NF-κB pathways.