Nitric oxide and mitochondrial respiration

Transcriptional and Metabolic Changes Associated with Phytoglobin Expression during Germination of Barley Seeds

To understand how the class 1 phytoglobin is involved in germination process via the modulation of the nitric oxide (NO) metabolism, we performed the analysis of physiological and molecular parameters in the embryos of transgenic barley (Hordeum vulgare L. cv Golden Promise) plants differing in expression levels of the phytoglobin (Pgb1) gene during the first 48 h of germination. Overexpression of Pgb1 resulted in a higher rate of germination, higher protein content and higher ATP/ADP ratios. This was accompanied by a lower rate of NO emission after radicle protrusion, as compared to the wild type and downregulating line, and a lower rate of S-nitrosylation of proteins in the first hours postimbibition. The rate of fermentation estimated by the expression and activity of alcohol dehydrogenase was significantly higher in the Pgb1 downregulating line, the same tendency was observed for nitrate reductase expression. The genes encoding succinate dehydrogenase and pyruvate dehydrogenase complex subunits were more actively expressed in embryos of the seeds overexpressing Pgb1. It is concluded that Pgb1 expression in embryo is essential for the maintenance of redox and energy balance before radicle protrusion, when seeds experience low internal oxygen concentration and exerts the effect on metabolism during the initial development of seedlings.

Neuroprotective efficacy of nano-CoQ against propionic acid toxicity in rats: Role of BDNF and CREB protein expressions

Propionic acid (PRA) is used as a food preservative. This study was aimed to investigate the neuroprotective effect of acetyl-l-carnitine (ALC) and nano-Coenzyme Q (N-CoQ) on brain intoxication induced by PRA in rats. Rats were divided into five groups: group I: control; group II: received PRA; group III: received ALC; group IV: received N-CoQ; and group V: received ALC and N-CoQ for 5 days. The antioxidants in question markedly ameliorated serum interleukin-1β and tumor necrosis factor-α, and brain NO, lipid peroxide, glutathione, and superoxide dismutase levels as well as protein expression of brain-derived neurotrophic factor (BDNF) and P-cyclic-AMP response element-binding protein (CREB) that were altered by a toxic dose of PRA, as well as histopathological alterations, including improvement of the cerebellum architecture. Interestingly, the combination therapy of ALC and N-CoQ achieved the most neuroprotective effect compared with monotherapies. The current study established that N-CoQ is considered as a useful tool to prevent brain injury induced by PRA. BDNF and CREB proteins are involved in both PRA neurotoxicity and treatment.

Behaviorally-Mediated Entrainment of Whole-Body Metabolic Processes: Conservation and Evolutionary Development of Mitochondrial Respiratory Complexes

The relaxation response derives its health benefits by reestablishing “normal” equilibria between the sympathetic and parasympathetic branches of the autonomic nervous system. Recent work suggests that this behavioral training provides positive effects on mitochondrial bioenergetics, insulin secretion, and reductions in pro-inflammatory and stress-related pathways. We have previously contended, however, that correlative associations of relaxation training with positive changes in gene expression in selected biological systems are strongly suggestive of adaptive physiological changes, but do not elucidate an underlying, clinically compelling, unified mechanism of action consistent with its purported positive health effects. We surmise that any plausible model of behaviorally-mediated regulatory effects on whole-body metabolic processes must be intrinsically broad-based and multifaceted via integration of differential contributions of functionally interactive peripheral and CNS organ systems. Accordingly, the initiation of multiple cellular protective/anti-bio-senescence processes may have emerged during evolutionary development to ensure the survival of hybrid prokaryotic/eukaryotic progenitor cells, given the evolvement of oxidative metabolism and its associated negative byproducts. As an essential corollary, preservation and adaptation of multifaceted regulatory molecules, notably nitric oxide, paralleled the development of eukaryotic cell types via multifaceted stereo-selective recognition and conformational matching by complex biochemical and molecular enzyme systems. Hence, the relaxation response may be a manifestation of a metabolic corrective process/response, that may now include cognition (“awareness”).

Mitochondrial respiratory chain inhibition and Na+K+ATPase dysfunction are determinant factors modulating the toxicity of nickel in the brain of indian catfish Clarias batrachus L

Nickel is a potential neurotoxic pollutant inflicting damage in living organisms, including fish, mainly through oxidative stress. Previous studies have demonstrated the impact of nickel toxicity on mitochondrial function, but there remain lacunae on the damage inflicted at mitochondrial respiratory level. Deficient mitochondrial function usually affects the activities of important adenosinetriphosphatases responsible for the maintenance of normal neuronal function, namely Na⁺K⁺ATPase, as explored in our study. Previous reports demonstrated the dysfunction of this enzyme upon nickel exposure but the contributing factors for the inhibition of this enzyme remained unexplored. The main purpose of this study was to elucidate the impact of nickel neurotoxicity on mitochondrial respiratory complexes and Na⁺K⁺ATPase in the piscine brain and to determine the contributing factors that had an impact on the same. Adult Clarias batrachus were exposed to nickel treated water at 10% and 20% of the 96 h LC50 value (41 mg.l^–1) respectively and sampled on 20, 40 and 60 days. Exposure of fish brain to nickel led to partial inhibition of complex IV of mitochondrial respiratory chain, however, the activities of complex I, II and III remained unaltered. This partial inhibition of mitochondrial respiratory chain might have been sufficient to lower mitochondrial energy production in mitochondria that contributed to the partial dysfunction of Na⁺K⁺ATPase. Besides energy depletion other contributing factors were involved in the dysfunction of this enzyme, like loss of thiol groups for enzyme activity and lipid peroxidation-derived end products that might have induced conformational and functional changes. However, providing direct evidence for such conformational and functional changes of Na⁺K⁺ATPase was beyond the scope of the present study. In addition, immunoblotting results also showed a decrease in Na⁺K⁺ATPase protein expression highlighting the impact of nickel neurotoxicity on the expression of the enzyme itself. The implication of the inhibition of mitochondrial respiration and Na⁺K⁺ATPase dysfunction was the neuronal death as evidenced by enhanced caspase-3 and caspase-9 activities. Thus, this study established the deleterious impact of nickel neurotoxicity on mitochondrial functions in the piscine brain and identified probable contributing factors that can act concurrently in the inhibition of Na⁺K⁺ATPase. This study also provided a vital clue about the specific areas that the therapeutic agents should target to counter nickel neurotoxicity.

Exogenous L-Carnitine Promotes Plant Growth and Cell Division by Mitigating Genotoxic Damage of Salt Stress

L-carnitine is a fundamental ammonium compound responsible for energy metabolism in all living organisms. It is an oxidative stress regulator, especially in bacteria and yeast and lipid metabolism in plants. Besides its metabolic functions, l-carnitine has detoxification and antioxidant roles in the cells. Due to the complex interrelationship of l-carnitine between lipid metabolism and salinity dependent oxidative stress, this study investigates the exogenous l-carnitine (1 mM) function on seed germination, cell division and chromosome behaviour in barley seeds (Hordeum vulgare L. cv. Bulbul-89) under different salt stress concentrations (0, 0.25, 0.30 and 0.35 M). The present work showed that l-carnitine pretreatment could not be successful to stimulate cell division on barley seeds under non-stressed conditions compared to stressed conditions. Depending on increasing salinity without pretreatment with l-carnitine, the mitotic index significantly decreased in barley seeds. Pretreatment of barley seeds with l-carnitine under salt stress conditions was found promising as a plant growth promoter and stimulator of mitosis. In addition, pretreatment of barley seeds with l-carnitine alleviated detrimental effects of salt stress on chromosome structure and it protected cells from the genotoxic effects of salt. This may be caused by the antioxidant and protective action of the l-carnitine. Consequently, this study demonstrated that the exogenous application of 1 mM l-carnitine mitigates the harmful effects of salt stress by increasing mitosis and decreasing DNA damage caused by oxidative stress on barley seedlings.

Inducible nitric oxide synthase-derived extracellular nitric oxide flux regulates proinflammatory responses at the single cell level

The role of nitric oxide (NO) in cancer progression has largely been studied in the context of tumor NOS2 expression. However, pro- versus anti-tumor signaling is also affected by tumor cell-macrophage interactions. While these cell-cell interactions are partly regulated by NO, the functional effects of NO flux on proinflammatory (M1) macrophages are unknown. Using a triple negative murine breast cancer model, we explored the potential role of macrophage Nos2 on 4T1 tumor progression. The effects of NO on macrophage phenotype were examined in bone marrow derived macrophages from wild type and Nos2^−/− mice following in vitro stimulation with cytokine/LPS combinations to produce low, medium, and high NO flux. Remarkably, Nos2 induction was spatially distinct, where Nos2^high cells expressed low cyclooxygenase-2 (Cox2) and vice versa. Importantly, in vitro M1 polarization with IFNγ+LPS induced high NO flux that was restricted to cells harboring depolarized mitochondria. This flux altered the magnitude and spatial extent of hypoxic gradients. Metabolic and single cell analyses demonstrated that single cell Nos2 induction limited the generation of hypoxic gradients in vitro, and Nos2-dependent and independent features may collaborate to regulate M1 functionality. It was found that Cox2 expression was important for Nos2^high cells to maintain NO tolerance. Furthermore, Nos2 and Cox2 expression in 4T1 mouse tumors was spatially orthogonal forming distinct cellular neighborhoods. In summary, the location and type of Nos2^high cells, NO flux, and the inflammatory status of other cells, such as Cox2^high cells in the tumor niche contribute to Nos2 inflammatory mechanisms that promote disease progression of 4T1 tumors.

Bioinspired oxidation of oximes to nitric oxide with dioxygen by a nonheme iron(II) complex

The ability of two iron(II) complexes, [(Tp^Ph2)Fe^II(benzilate)] (1) and [(Tp^Ph2)(Fe^II)₂(NPP)₃] (2) (Tp^Ph2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate, NPP-H = α-isonitrosopropiophenone), of a monoanionic facial N3 ligand in the O₂-dependent oxidation of oximes is reported. The mononuclear complex 1 reacts with dioxygen to decarboxylate the iron-coordinated benzilate. The oximate-bridged dinuclear complex (2), which contains a high-spin (Tp^Ph2)Fe^II unit and a low-spin iron(II)-oximate unit, activates dioxygen at the high-spin iron(II) center. Both the complexes exhibit the oxidative transformation of oximes to the corresponding carbonyl compounds with the incorporation of one oxygen atom from dioxygen. In the oxidation process, the oxime units are converted to nitric oxide (NO) or nitroxyl (HNO). The iron(II)-benzilate complex (1) reacts with oximes to afford HNO, whereas the iron(II)-oximate complex (2) generates NO. The results described here suggest that the oxidative transformation of oximes to NO/HNO follows different pathways depending upon the nature of co-ligand/reductant.Graphic abstract.

Effects of isoflurane on complex II‑associated mitochondrial respiration and reactive oxygen species production: Roles of nitric oxide and mitochondrial KATP channels

Volatile anesthetics may protect the heart against ischemia‑reperfusion injury via the direct action on mitochondrial complexes and by regulating the production of reactive oxygen species (ROS). Recently, we reported that isoflurane induced the attenuation of mitochondrial respiration caused by complex I substrates. This process was not associated with endogenous production of mitochondrial nitric oxide (NO). In the present study, we investigated the effects of isoflurane on mitochondrial respiration and ROS production using complex II substrates. The detailed mechanism of these effects was explored with regards to NO production and the expression of mitochondrial ATP‑dependent K+ (mKATP) channels. Mitochondria were isolated from the heart of Sprague‑Dawley rats. The respiratory rates of mitochondria (0.5 mg/ml) were measured via polarography at 28˚C with computer‑controlled Clark‑type O2 electrodes. The complex II substrate succinate (5 mM) was used; 0.25 mM of isoflurane was administered prior to ADP‑initiated state 3 respiration. The mitochondrial membrane potential (ΔΨm) was measured under treatment with the substrate succinate, or succinate in the presence of the complex I inhibitor rotenone. The detection was achieved in a cuvette‑based spectrophotometer operating at wavelengths of 503 nm (excitation) 527 nm (emission) in the presence of 50 nM of the fluorescent dye rhodamine 123. The H2O2 release rates in the mitochondria were measured spectrophotometrically with succinate, or succinate and rotenone using the fluorescent dye Amplex red (12.5‑25 µM). The results indicated that isoflurane increased the state 3 and 4 respiration rates caused by succinate, which were higher than those noted in the control group in the presence of succinate alone. The NOS inhibitor L‑NIO or the NO‑sensitive guanylyl cyclase 1H‑[1,2,4]oxadiazolo[4,3‑a]quinoxalin‑1‑one did not inhibit the increase in the respiration rate (state 3) induced by isoflurane. The ROS scavengers SPBN and manganese (III) tetrakis (4‑benzoic acid) porphyrin chloride inhibited the increase in the respiration rate (state 3 and 4) induced by isoflurane. This effect was not noted for the putative KATP channel blockers 5‑hydroxydecanoic acid and glibenclamide. Isoflurane caused a greater decrease in the concentration of H2O2 during ADP‑initiated state 3 respiration, and L‑N5‑(1‑Iminoethyl)‑ornithine did not inhibit this effect. In conclusion, isoflurane was determined to modulate mitochondrial respiration and ROS production caused by the complex II substrate succinate. These effects were independent of endogenous mitochondrial NO generation and mitochondrial KATP channel opening.

Nitric oxide accelerates germination via the regulation of respiration in chickpea

Seed germination is crucial for the plant life cycle. We investigated the role of nitric oxide (NO) in two chickpea varieties that differ in germination capacity: Kabuli, which has a low rate of germination and germinates slowly, and Desi, which shows improved germination properties. Desi produced more NO than Kabuli and had lower respiratory rates. As a result of the high respiration rates, Kabuli had higher levels of reactive oxygen species (ROS). Treatment with the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) reduced respiration in Kabuli and decreased ROS levels, resulting in accelerated germination rates. These findings suggest that NO plays a key role in the germination of Kabuli. SNAP increased the levels of transcripts encoding enzymes involved in carbohydrate metabolism and the cell cycle. Moreover, the levels of amino acids and organic acids were increased in Kabuli as a result of SNAP treatment. 1H-nuclear magnetic resonance analysis revealed that Kabuli has a higher capacity for glucose oxidation than Desi. An observed SNAP-induced increase in 13C incorporation into soluble alanine may result from enhanced oxidation of exogenous [13C]glucose via glycolysis and the pentose phosphate pathway. A homozygous hybrid that originated from a recombinant inbred line population of a cross between Desi and Kabuli germinated faster and had increased NO levels and a reduced accumulation of ROS compared with Kabuli. Taken together, these findings demonstrate the importance of NO in chickpea germination via the control of respiration and ROS accumulation.

Mechanism of nitrite-dependent NO synthesis by human sulfite oxidase

In addition to nitric oxide (NO) synthases, molybdenum-dependent enzymes have been reported to reduce nitrite to produce NO. Here, we report the stoichiometric reduction in nitrite to NO by human sulfite oxidase (SO), a mitochondrial intermembrane space enzyme primarily involved in cysteine catabolism. Kinetic and spectroscopic studies provide evidence for direct nitrite coordination at the molybdenum center followed by an inner shell electron transfer mechanism. In the presence of the physiological electron acceptor cytochrome c, we were able to close the catalytic cycle of sulfite-dependent nitrite reduction thus leading to steady-state NO synthesis, a finding that strongly supports a physiological relevance of SO-dependent NO formation. By engineering SO variants with reduced intramolecular electron transfer rate, we were able to increase NO generation efficacy by one order of magnitude, providing a mechanistic tool to tune NO synthesis by SO.

Mitochondrial metabolism: Inducer or therapeutic target in tumor immune-resistance?

Mitochondria have been considered for a long time only as the principal source of building blocks and energy upon aerobic conditions. Recently they emerged as key players in cell proliferation, invasion and resistance to therapy. The most aggressive tumors are able to evade the immune-surveillance. Alterations in the mitochondria metabolism either in cancer cells or in host immune system cells are involved in such tumor-induced immune-suppression. This review will focus on the main mitochondrial dysfunctions in tumor and immune cell populations determining immune-resistance, and on the therapies that may target mitochondrial metabolism and restore a powerful anti-tumor immune-activity.

Modulating effect of tiron on the capability of mitochondrial oxidative phosphorylation in the brain of rats exposed to radiation or manganese toxicity

The brain is an important organ rich in mitochondria and more susceptible to oxidative stress. Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) is a potent antioxidant. This study aims to evaluate the effect of tiron on the impairment of brain mitochondria induced by exposure to radiation or manganese (Mn) toxicity. We assessed the capability of oxidative phosphorylation (OXPHOS) through determination of mitochondrial redox state, the activity of electron transport chain (ETC), and Krebs cycle as well as the level of adenosine triphosphate (ATP) production. Rats were exposed to 7 Gy of γ-rays or injected i.p. with manganese chloride (100 mg/kg), then treated with tiron (471 mg/kg) for 7 days. The results showed that tiron treatment revealed positive modulation on the mitochondrial redox state manifested by a marked decrease of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and total nitrate/nitrite (NO_x) associated with a significant increase in total antioxidant capacity (TAC), glutathione (GSH) content, manganese superoxide dismutase (MnSOD), and glutathione peroxidase (GPx) activities. Moreover, tiron can increase the activity of ETC through preventing the depletion in the activity of mitochondrial complexes (I, II, III, and IV), an elevation of coenzyme Q10 (CoQ10) and cytochrome c (Cyt-c) levels. Additionally, tiron showed a noticeable increase in mitochondrial aconitase (mt-aconitase) activity as the major component of Krebs cycle to maintain a high level of ATP production. Tiron also can restore mitochondrial metal homeostasis through positive changes in the levels of calcium (Ca), iron (Fe), Mn, and copper (Cu). It can be concluded that tiron may be used as a good mitigating agent to attenuate the harmful effects on the brain through the inhibition of mitochondrial injury post-exposure to radiation or Mn toxicity.

Effects of elamipretide on skeletal muscle in dogs with experimentally induced heart failure

AIMS

Elamipretide (ELAM), an aromatic-cationic tetrapeptide, interacts with cardiolipin and normalizes dysfunctional mitochondria of cardiomyocytes. This study examined the effects of ELAM on skeletal muscle mitochondria function in dogs with chronic heart failure (HF).

METHODS AND RESULTS

Studies were performed in skeletal muscle biopsy specimens obtained from normal dogs (n = 7) and dogs with chronic intracoronary microembolization-induced HF (n = 14) treated with subcutaneous ELAM 0.5 mg/kg (HF + ELAM, n = 7) or vehicle (normal saline control, HF-CON, n = 7). After 3 months of therapy, triceps skeletal muscle samples were obtained from all dogs, and the proportion of type 1 and type 2 fibres was assessed. Mitochondria isolated from myofibrils of the vastus lateralis skeletal muscle exposed in vitro to ELAM for 1 h were used to assess mitochondrial function. The proportion of skeletal muscle type 1 fibres was lower in HF-CON dogs compared with normal dogs (23 ± 4 vs. 32 ± 5%, P < 0.05). Treatment with ELAM restored a near-normal fibre-type composition (31 ± 7%, P < 0.05 vs. HF-CON). Skeletal muscle mitochondria showed significantly lower levels of adenosine diphosphate-dependent mitochondrial respiration (100 ± 9 vs. 164 ± 15 natom O/min/mg protein, P < 0.05), mitochondrial membrane potential (0.17 ± 0.03 vs. 0.53 ± 0.03 red/green fluorescence ratio, P < 0.05), mitochondrial permeability transition pore (38 ± 3 vs. 62 ± 2 relative light units, P < 0.05), maximum rate of adenosine triphosphate synthesis (3284 ± 418 vs. 8835 ± 423 RLU/μg protein, P < 0.05), and cytochrome c oxidase activity (1390 ± 108 vs. 2459 ± 210 natom O/min/mg protein, P < 0.05) compared with normal dogs. Exposure of skeletal muscle myofibrillar mitochondria from HF dogs to ELAM showed a dose-dependent improvement/normalization of all measures of mitochondrial function. In mitochondria from skeletal muscle of HF dogs exposed to 0.10 μM ELAM, adenosine diphosphate-dependent mitochondrial respiration increased to 183 ± 18 natom O/min/mg protein, membrane potential increased to 0.30 ± 0.03 red/green fluorescence ratio, mitochondrial permeability transition pore increased to 54 ± 4 RLU, maximum rate of adenosine triphosphate synthesis increased to 4423 ± 414, and cytochrome c oxidase activity increased to 2033 ± 191 natom O/min/mg protein. Exposure of skeletal muscle myofibrillar mitochondria from normal dogs to ELAM had no effect on mitochondrial function parameters.

CONCLUSIONS

The results indicate that ELAM, previously shown to positively influence mitochondrial function of the failing heart, can also positively impact mitochondrial function of skeletal muscle and potentially help restore skeletal muscle function and improve exercise tolerance.

Absence of Nonclassical Monocytes in Hemolytic Patients: Free Hb and NO-Mediated Mechanism

In a recent work, we have described the kinetics among the monocyte subsets in the peripheral blood of hemolytic patients including paroxysmal nocturnal hemoglobinuria (PNH) and sickle cell disease (SCD). After engulfing Hb-activated platelets, classical monocytes (CD14⁺CD16^-) significantly transformed into highly inflammatory (CD14⁺CD16^hi) subsets in vitro. An estimated 40% of total circulating monocytes in PNH and 70% in SCD patients existed as CD14⁺CD16^hi subsets. In this study, we show that the nonclassical (CD14^dimCD16⁺) monocyte subsets are nearly absent in patients with PNH or SCD, compared to 10-12% cells in healthy individuals. In mechanism, we have described the unique role of both free Hb and nitric oxide (NO) in reducing number of nonclassical subsets more than classical monocytes. After engulfing Hb-activated platelets, the monocytes including nonclassical subsets acquired rapid cell death within 12 h in vitro. Further, the treatment to monocytes either with the secretome of Hb-activated platelets containing NO and free Hb or purified free Hb along with GSNO (a physiological NO donor) enhanced rapid cell death. Besides, our data from both PNH and SCD patients exhibited a direct correlation between intracellular NO and cell death marker 7AAD in monocytes from the peripheral blood. Our data together suggest that due to the immune surveillance nature, the nonclassical or patrolling monocytes are encountered frequently by Hb-activated platelets, free Hb, and NO in the circulation of hemolytic patients and are predisposed to die rapidly.

Molecular Mechanisms of Nitric Oxide in Cancer Progression, Signal Transduction, and Metabolism

SIGNIFICANCE

Cancer is a complex disease, which not only involves the tumor but its microenvironment comprising different immune cells as well. Nitric oxide (NO) plays specific roles within tumor cells and the microenvironment and determines the rate of cancer progression, therapy efficacy, and patient prognosis. Recent Advances: Key understanding of the processes leading to dysregulated NO flux within the tumor microenvironment over the past decade has provided better understanding of the dichotomous role of NO in cancer and its importance in shaping the immune landscape. It is becoming increasingly evident that nitric oxide synthase 2 (NOS2)-mediated NO/reactive nitrogen oxide species (RNS) are heavily involved in cancer progression and metastasis in different types of tumor. More recent studies have found that NO from NOS2+ macrophages is required for cancer immunotherapy to be effective.

CRITICAL ISSUES

NO/RNS, unlike other molecules, are unique in their ability to target a plethora of oncogenic pathways during cancer progression. In this review, we subcategorize the different levels of NO produced by cells and shed light on the context-dependent temporal effects on cancer signaling and metabolic shift in the tumor microenvironment.

FUTURE DIRECTIONS

Understanding the source of NO and its spaciotemporal profile within the tumor microenvironment could help improve efficacy of cancer immunotherapies by improving tumor infiltration of immune cells for better tumor clearance.

Inhibition of Classical and Alternative Modes of Respiration in Candida albicans Leads to Cell Wall Remodeling and Increased Macrophage Recognition

The human fungal pathogen Candida albicans requires respiratory function for normal growth, morphogenesis, and virulence. Mitochondria therefore represent an enticing target for the development of new antifungal strategies. This possibility is bolstered by the presence of characteristics specific to fungi. However, respiration in C. albicans, as in many fungal organisms, is facilitated by redundant electron transport mechanisms, making direct inhibition a challenge. In addition, many chemicals known to target the electron transport chain are highly toxic. Here we made use of chemicals with low toxicity to efficiently inhibit respiration in C. albicans We found that use of the nitric oxide donor sodium nitroprusside (SNP) and of the alternative oxidase inhibitor salicylhydroxamic acid (SHAM) prevents respiration and leads to a loss of viability and to cell wall rearrangements that increase the rate of uptake by macrophages in vitro and in vivo We propose that treatment with SNP plus SHAM (SNP+SHAM) leads to transcriptional changes that drive cell wall rearrangement but which also prime cells to activate the transition to hyphal growth. In line with this, we found that pretreatment of C. albicans with SNP+SHAM led to an increase in virulence. Our data reveal strong links between respiration, cell wall remodeling, and activation of virulence factors. Our findings demonstrate that respiration in C. albicans can be efficiently inhibited with chemicals that are not damaging to the mammalian host but that we need to develop a deeper understanding of the roles of mitochondria in cellular signaling if they are to be developed successfully as a target for new antifungals.IMPORTANCE Current approaches to tackling fungal infections are limited, and new targets must be identified to protect against the emergence of resistant strains. We investigated the potential of targeting mitochondria, which are organelles required for energy production, growth, and virulence, in the human fungal pathogen Candida albicans Our findings suggest that mitochondria can be targeted using drugs that can be tolerated by humans and that this treatment enhances their recognition by immune cells. However, release of C. albicans cells from respiratory inhibition appears to activate a stress response that increases the levels of traits associated with virulence. Our results make it clear that mitochondria represent a valid target for the development of antifungal strategies but that we must determine the mechanisms by which they regulate stress signaling and virulence ahead of successful therapeutic advance.

Augmentation of Whole-Body Metabolic Status by Mind-Body Training: Synchronous Integration of Tissue- and Organ-Specific Mitochondrial Function

The objective of our concise review is to elaborate an evidence-based integrative medicine model that incorporates functional linkages of key aspects of cortically-driven mind-body training procedures to biochemical and molecular processes driving enhanced cellular bioenergetics and whole-body metabolic advantage. This entails the adoption of a unified biological systems approach to selectively elucidate basic biochemical and molecular events responsible for achieving physiological relaxation of complex cellular structures. We provide accumulated evidence in support of the potential synergy of voluntary breathing exercises in combination with meditation and/or complementary cognitive tasks to promote medically beneficial enhancements in whole-body relaxation, anti-stress mechanisms, and restorative sleep. Accordingly, we propose that the widespread metabolic and physiological advantages emanating from a sustained series of complementary mind-body exercises will ultimately engender enhanced functional integration of cortical and limbic areas controlling voluntary respiratory processes with autonomic brainstem neural pattern generators. Finally, a unified mechanism is proposed that links behaviorally-mediated enhancements of whole-body metabolic advantage to optimization of synchronous regulation of mitochondrial oxygen utilization via recycling of nitrite and nitric oxide by iron-sulfur centers of coupled respiratory complexes and nitrite reductases.

Controlled Delivery of Nitric Oxide for Cancer Therapy

Nitric oxide (NO) is a short-lived, endogenously produced, signaling molecule which plays multiple roles in mammalian physiology. Underproduction of NO is associated with several pathological processes; hence a broad range of NO donors have emerged as potential therapeutics for cardiovascular and respiratory disorders, wound healing, the immune response to infection, and cancer. However, short half-lives, chemical reactivity, rapid systemic clearance, and cytotoxicity have hindered the clinical development of most low molecular weight NO donors. Hence, for controlled NO delivery, there has been extensive effort to design novel NO-releasing biomaterials for tumor targeting. This review covers the effects of NO in cancer biology, NO releasing moieties which can be used for NO delivery, and current advances in the design of NO releasing biomaterials focusing on their applications for tumor therapy.

Nitric oxide-releasing nanoparticles improve doxorubicin anticancer activity

Purpose

Anticancer drug delivery systems are often limited by hurdles, such as off-target distribution, slow cellular internalization, limited lysosomal escape, and drug resistance. To overcome these limitations, we have developed a stable nitric oxide (NO)-releasing nanoparticle (polystyrene-maleic acid [SMA]-tert-dodecane S-nitrosothiol [tDodSNO]) with the aim of enhancing the anticancer properties of doxorubicin (Dox) and a Dox-loaded nanoparticle (SMA-Dox) carrier.

Materials and methods

Effects of SMA-tDodSNO and/or in combination with Dox or SMA-Dox on cell viability, apoptosis, mitochondrial membrane potential, lysosomal membrane permeability, tumor tissue, and tumor growth were studied using in vitro and in vivo model of triple-negative breast cancer (TNBC). In addition, the concentrations of SMA-Dox and Dox in combination with SMA-tDodSNO were measured in cells and tumor tissues.

Results

Combination of SMA-tDodSNO and Dox synergistically decreased cell viability and induced apoptosis in 4T1 (TNBC cells). Incubation of 4T1 cells with SMA-tDodSNO (40 µM) significantly enhanced the cellular uptake of SMA-Dox and increased Dox concentration in the cells resulting in a twofold increase (P<0.001). Lysosomal membrane integrity, evaluated by acridine orange (AO) staining, was impaired by 40 µM SMA-tDodSNO (P<0.05 vs control) and when combined with SMA-Dox, this effect was significantly potentiated (P<0.001 vs SMA-Dox). Subcutaneous administration of SMA-tDodSNO (1 mg/kg) to xenografted mice bearing 4T1 cells showed that SMA-tDodSNO alone caused a twofold decrease in the tumor size compared to the control group. SMA-tDodSNO in combination with SMA-Dox resulted in a statistically significant 4.7-fold reduction in the tumor volume (P<0.001 vs control), without causing significant toxicity as monitored through body weight loss.

Conclusion

Taken together, these results suggest that SMA-tDodSNO can be used as a successful strategy to increase the efficacy of Dox and SMA-Dox in a model of TNBC.

Nitric oxide triggers the assembly of "type II" stress granules linked to decreased cell viability

We show that 3-morpholinosydnonimine (SIN-1)-induced nitric oxide (NO) triggers the formation of SGs. Whereas the composition of NO-induced SGs is initially similar to sodium arsenite (SA)-induced type I (cytoprotective) SGs, the progressive loss of eIF3 over time converts them into pro-death (type II) SGs. NO-induced SG assembly requires the phosphorylation of eIF2α, but the transition to type II SGs is temporally linked to the mTOR-regulated displacement of eIF4F complexes from the m⁷ guanine cap. Whereas SA does not affect mitochondrial morphology or function, NO alters mitochondrial integrity and function, resulting in increased ROS production, decreased cytoplasmic ATP, and plasma membrane permeabilization, all of which are supported by type II SG assembly. Thus, cellular energy balance is linked to the composition and function of NO-induced SGs in ways that determine whether cells live or die.

Composition and biochemical properties of l-carnitine fortified Makgeolli brewed by using fermented buckwheat

Makgeolli is a traditional Korean alcoholic rice beverage. It is brewed of ingredients containing starch, Nuruk, and water. In order to improve the quality and functionality of Makgeolli, the Rhizopus oligosporus fermented buckwheat containing 18.7 mg/kg of l-carnitine were utilized to brew l-carnitine fortified Makgeolli with rice. Makgeolli was prepared in two-stage fermentation method and total rutin and quercetin in each fermented buckwheat Makgeolli were increased 1.8-fold greater than buckwheat Makgeolli. DPPH antioxidant activity was enhanced in fermented buckwheat Makgeolli than buckwheat Makgeolli (21.9%-65.7%). The amounts of l-carnitine in rice Makgeolli, buckwheat Makgeolli, and fermented buckwheat Makgeolli were 0.9, 0.8-1.0, and 1.0-1.9 mg/L, respectively. The fermented buckwheat Makgeolli not only promoted health benefit by increasing l-carnitine and flavonols, but also made effective alcohol production (2.8%-8.4%) compared to common buckwheat Makgeolli, indicating the potential industrial application with health benefits.

Insights in pathogenesis of multiple sclerosis: nitric oxide may induce mitochondrial dysfunction of oligodendrocytes

Demyelinating diseases, such as multiple sclerosis (MS), are kinds of common diseases in the central nervous system (CNS), and originated from myelin loss and axonal damage. Oligodendrocyte dysfunction is the direct reason of demyelinating lesions in the CNS. Nitric oxide (NO) plays an important role in the pathological process of demyelinating diseases. Although the neurotoxicity of NO is more likely mediated by peroxynitrite rather than NO itself, NO can impair oligodendrocyte energy metabolism through mediating the damaging of mitochondrial DNA, mitochondrial membrane and mitochondrial respiratory chain complexes. In the progression of MS, NO can mainly mediate demyelination, axonal degeneration and cell death. Hence, in this review, we extensively discuss endangerments of NO in oligodendrocytes (OLs), which is suggested to be the main mediator in demyelinating diseases, e.g. MS. We hypothesize that NO takes part in MS through impairing the function of monocarboxylate transporter 1, especially causing axonal degeneration. Then, it further provides a new insight that NO for OLs may be a reliable therapeutic target to ameliorate the course of demyelinating diseases.

Effect of Melittin on Metabolomic Profile and Cytokine Production in PMA-Differentiated THP-1 Cells

Melittin, the major active peptide of honeybee venom (BV), has potential for use in adjuvant immunotherapy. The immune system response to different stimuli depends on the secretion of different metabolites from macrophages. One potent stimulus is lipopolysaccharide (LPS), a component isolated from gram-negative bacteria, which induces the secretion of pro-inflammatory cytokines in macrophage cell cultures. This secretion is amplified when LPS is combined with melittin. In the present study, pure melittin was isolated from whole BV by flash chromatography to obtain pure melittin. The ability of melittin to enhance the release of tumour necrosis factor-α (TNF-α), Interleukin (IL-1β, IL-6, and IL-10) cytokines from a macrophage cell line (THP-1) was then assessed. The response to melittin and LPS, applied alone or in combination, was characterised by metabolic profiling, and the metabolomics results were used to evaluate the potential of melittin as an immune adjuvant therapy. The addition of melittin enhanced the release of inflammatory cytokines induced by LPS. Effective chromatographic separation of metabolites was obtained by liquid chromatography-mass spectrometry (LC-MS) using a ZIC-pHILIC column and an ACE C4 column. The levels of 108 polar and non-polar metabolites were significantly changed (p ˂ 0.05) following cell activation by the combination of LPS and melittin when compared to untreated control cells. Overall, the findings of this study suggested that melittin might have a potential application as a vaccine adjuvant.

Characterization of quinoa (Chenopodium quinoa) fermented by Rhizopus oligosporus and its bioactive properties

Quinoa is a pseudocereal that contains high quality protein, minerals, vitamins, polyphenols, and phytosterols. In this study, quinoa was fermented by Rhizopus oligosporus (R. oligosporus) up to 5 days and the functional compounds (l-carnitine, GABA, vanillic acid and gallic acid) were analyzed by LC/MS. The amounts of l-carnitine and GABA were 0.13 mg/kg and 540 mg/kg for nonfermented quinoa (NF), 3.15 mg/kg and 1040 mg/kg for fermented quinoa at 3 days (3F), and 1.54 mg/kg and 810 mg/kg for fermented quinoa at 5 days (5F). The vanillic acid and gallic acid were 1.3 and 0.1 mg/kg for NF, 1.55 and 2.37 mg/kg for 3F, and 1.83 and 0.84 mg/kg for 5F, respectively. Total phenolic contents and total flavonoids contents were 41 mg gallic acid (GAE)/kg and 13 mg quercetin equivalent (QE)/kg for NF, 74 mg GAE/kg and 16 mg QE/kg for 3F, and 80 mg GAE/kg and 19 mg QE/kg for 5F, respectively. Antioxidant activity (SC₅₀) was 3.6 mg/mL for NF, 3.4 mg/mL for 3F, and 2.3 mg/mL for 5F. Nitric oxide production on RAW264.7 macrophages of fermented quinoa revealed 29% and 56% inhibition of nitric oxide production for NF and 5F, respectively. Therefore, fermented quinoa can be used as a healthy and valuable food product.

Effect of Hepatic Preconditioning with the Use of Methylene Blue on the Liver of Wistar Rats Submitted to Ischemia and Reperfusion

BACKGROUND

The liver may be injured in situations where it is submitted to ischemia, such as partial hepatectomy and liver transplantation. In all cases, ischemia is followed by reperfusion and, although it is essential for the reestablishment of tissue function, reperfusion may cause greater damage than ischemia, an injury characterized as ischemia-reperfusion (I/R) damage. The aim of this work was to analyze the effect of ischemic preconditioning with the use of methylene blue (MB; 15 mg/kg) 5 or 15 minutes before I/R (IRMB5' and IRMB15', respectively) on the hepatic injury occurring after I/R.

METHODS

Twenty-eight male Wistar rats were used, and liver samples submitted to partial ischemia (IR) or not (NI) were obtained from the same animal. The samples were divided into 7 groups. Data were analyzed statistically by means of the nonparametric Mann-Whitney test and Wilcoxon Matched test, with the level of significance set at 5% (P < .05).

RESULTS

The rate of oxygen consumption by state 3 mitochondria was inhibited in all ischemic groups compared with the sham group (SH vs IR: P = .0052; SH vs IRMB5': P = .0006; SH vs IRMB15': P = .0048), which did not occur in the nonischemic contralateral portion of the same liver (SH vs NI: P = .7652; SH vs NIMB5': P = .059; SH vs NIMB15': P = .3153). The inhibition of the rate of oxygen consumption by state 3 mitochondria was maintained in the presence of MB (IR vs IRMB5': P = .4563; IR vs IRMB15': P = .9021). The respiratory control ratio was reduced in all ischemic groups compared with the sham group, owing to the inhibition of oxygen consumption in state 3 (SH vs IR: P = .0151; SH vs IRMB5': P = .005; SH vs IRMB15': P = .0007).

CONCLUSIONS

Methylene blue had no effect on the mitochondrial respiratory parameters studied, but was able to reduce lipid peroxidation, preventing the production of reactive oxygen species (SH vs IRMB15': P = .0210).

Interaction of nitric oxide with the components of the plant mitochondrial electron transport chain

Mitochondria are not only major sites for energy production but also participate in several alternative functions, among these generation of nitric oxide (NO), and its different impacts on this organelle, is receiving increasing attention. The inner mitochondrial membrane contains the chain of protein complexes, and electron transfer via oxidation of various organic acids and reducing equivalents leads to generation of a proton gradient that results in energy production. Recent evidence suggests that these complexes are sources and targets for NO. Complex I and rotenone-insensitive NAD(P)H dehydrogenases regulate hypoxic NO production, while complex I also participates in the formation of a supercomplex with complex III under hypoxia. Complex II is a target for NO which, by inhibiting Fe-S centres, regulates reactive oxygen species (ROS) generation. Complex III is one of the major sites for NO production, and the produced NO participates in the phytoglobin-NO cycle that leads to the maintenance of the redox level and limited energy production under hypoxia. Expression of the alternative oxidase (AOX) is induced by NO under various stress conditions, and evidence exists that AOX can regulate mitochondrial NO production. Complex IV is another major site for NO production, which can also be linked to ATP generation via the phytoglobin-NO cycle. Inhibition of complex IV by NO can prevent oxygen depletion at the frontier of anoxia. The NO production and action on various complexes play a major role in NO signalling and energy metabolism.

Mitigating peroxynitrite mediated mitochondrial dysfunction in aged rat brain by mitochondria-targeted antioxidant MitoQ

Although reactive oxygen species mediated oxidative stress is a well-documented mechanism of aging, recent evidences indicate involvement of nitrosative stress in the same. As mitochondrial dysfunction is considered as one of the primary features of aging, the present study was designed to understand the involvement of nitrosative stress by studying the impact of a mitochondria-targeted antioxidant MitoQ, a peroxynitrite (ONOO^-) scavenger, on mitochondrial functions. Four groups of rats were included in this study: Group I: Young-6 months (-MitoQ), Group II: Aged-22 months (- MitoQ), Group III: Young-6 months (+ MitoQ), Group IV: Aged-22 months (+ MitoQ). The rats belonging to group III and IV were treated with oral administration of MitoQ (500 μM) daily through drinking water for 5 weeks. MitoQ efficiently suppressed synaptosomal lipid peroxidation and protein oxidation accompanied by diminution of nitrite production and protein bound 3-nitrotyrosine. MitoQ normalized enhanced caspase 3 and 9 activities in aged rat brains and efficiently reversed ONOO^- mediated mitochondrial complex I and IV inhibition, restored mitochondrial ATP production and lowered mitochondrial membrane potential loss. To ascertain these findings, a mitochondrial in vitro model (iron/ascorbate) was used involving different free radical scavengers and anti-oxidants. MitoQ provided better protection compared to mercaptoethylguanidine, N-nitro-L-arginine-methyl ester and superoxide dismutase establishing the predominancy of ONOO^- in the process compared to ^•NO and O ₂^•- . These results clearly highlight the involvement of nitrosative stress in aging process with MitoQ having therapeutic potential to fight against ONOO^- mediated aging deficits.

Alkaloids, Nitric Oxide, and Nitrite Reductases: Evolutionary Coupling as Key Regulators of Cellular Bioenergetics with Special Relevance to the Human Microbiome

Typical alkaloids expressed by prokaryotic and eukaryotic cells are small heterocyclic compounds containing weakly basic nitrogen groups that are critically important for mediating essential biological activities. The prototype opiate alkaloid morphine represents a low molecular mass heterocyclic compound that has been evolutionarily fashioned from a relatively restricted role as a secreted antimicrobial phytoalexin into a broad spectrum regulatory molecule. As an essential corollary, positive evolutionary pressure has driven the development of a cognate 6-transmembrane helical (TMH) domain μ3 opiate receptor that is exclusively responsive to morphine and related opiate alkaloids. A key aspect of “morphinergic” signaling mediated by μ3 opiate receptor activation is its functional coupling with regulatory pathways utilizing constitutive nitric oxide (NO) as a signaling molecule. Importantly, tonic and phasic intra-mitochondrial NO production exerts profound inhibitory effects on the rate of electron transport, H+ pumping, and O2 consumption. Given the pluripotent role of NO as a selective, temporally-defined chemical regulator of mitochondrial respiration and cellular bioenergetics, the expansion of prokaryotic denitrification systems into mitochondrial NO/nitrite cycling complexes represents a series of evolutionary modifications of existential proportions. Presently, our short review provides selective discussion of evolutionary development of morphine, opiate alkaloids, μ3 opiate receptors, and NO systems, within the perspectives of enhanced mitochondrial function, cellular bioenergetics, and the human microbiome.

13 reasons why the brain is susceptible to oxidative stress

The human brain consumes 20% of the total basal oxygen (O2) budget to support ATP intensive neuronal activity. Without sufficient O2 to support ATP demands, neuronal activity fails, such that, even transient ischemia is neurodegenerative. While the essentiality of O2 to brain function is clear, how oxidative stress causes neurodegeneration is ambiguous. Ambiguity exists because many of the reasons why the brain is susceptible to oxidative stress remain obscure. Many are erroneously understood as the deleterious result of adventitious O2 derived free radical and non-radical species generation. To understand how many reasons underpin oxidative stress, one must first re-cast free radical and non-radical species in a positive light because their deliberate generation enables the brain to achieve critical functions (e.g. synaptic plasticity) through redox signalling (i.e. positive functionality). Using free radicals and non-radical derivatives to signal sensitises the brain to oxidative stress when redox signalling goes awry (i.e. negative functionality). To advance mechanistic understanding, we rationalise 13 reasons why the brain is susceptible to oxidative stress. Key reasons include inter alia unsaturated lipid enrichment, mitochondria, calcium, glutamate, modest antioxidant defence, redox active transition metals and neurotransmitter auto-oxidation. We review RNA oxidation as an underappreciated cause of oxidative stress. The complex interplay between each reason dictates neuronal susceptibility to oxidative stress in a dynamic context and neural identity dependent manner. Our discourse sets the stage for investigators to interrogate the biochemical basis of oxidative stress in the brain in health and disease.

Loss of tafazzin results in decreased myoblast differentiation in C2C12 cells: A myoblast model of Barth syndrome and cardiolipin deficiency

Barth syndrome (BTHS) is an X-linked genetic disorder resulting from mutations in the tafazzin gene (TAZ), which encodes the transacylase that remodels the mitochondrial phospholipid cardiolipin (CL). While most BTHS patients exhibit pronounced skeletal myopathy, the mechanisms linking defective CL remodeling and skeletal myopathy have not been determined. In this study, we constructed a CRISPR-generated stable tafazzin knockout (TAZ-KO) C2C12 myoblast cell line. TAZ-KO cells exhibit mitochondrial deficits consistent with other models of BTHS, including accumulation of monolyso-CL (MLCL), decreased mitochondrial respiration, and increased mitochondrial ROS production. Additionally, tafazzin deficiency was associated with impairment of myocyte differentiation. Future studies should determine whether alterations in myogenic determination contribute to the skeletal myopathy observed in BTHS patients. The BTHS myoblast model will enable studies to elucidate mechanisms by which defective CL remodeling interferes with normal myocyte differentiation and skeletal muscle ontogenesis.

Elevated nitrate alters the metabolic activity of embryonic zebrafish

Nitrate accumulation in aquatic reservoirs from agricultural pollution has often been overlooked as a water quality hazard, yet a growing body of literature suggests negative effects on human and wildlife health following nitrate exposure. This research seeks to understand differences in oxygen consumption rates between different routes of laboratory nitrate exposure, whether via immersion or injection, in zebrafish (Danio rerio) embryos. Embryos were exposed within 1 h post fertilization (hpf) to 0, 10, and 100 mg/L NO₃-N with sodium nitrate, or to counter ion control (CIC) treatments using sodium chloride. Embryos in the immersion treatments received an injection of 4 nL of appropriate treatment solution into the perivitelline space. At 24 hpf, Oxygen Consumption Rates (OCR) were measured and recorded in vivo using the Agilent Technologies XF^e96 Extracellular Flux Analyzer and Spheroid Microplate. Immersion exposures did not induce significant changes in OCR, yet nitrate induced significant changes when injected through the embryo chorion. Injection of 10 and 100 mg/L NO₃-N down-regulated OCR compared to the control treatment group. Injection of the 100 mg/L CIC also significantly down-regulated OCR compared to the control treatment group. Interestingly, the 100 mg/L NO₃-N treatment further down-regulated OCR compared to the 100 mg/L CIC treatment, suggesting the potential for additive effects between the counter ion and the ion of interest. These data support that elevated nitrate exposure can alter normal metabolic activity by changing OCR in 24 hpf embryos. These results highlight the need for regularly examining the counter ion of laboratory nitrate compounds while conducting research with developing zebrafish, and justify examining different routes of laboratory nitrate exposure, as the chorion may act as an effective barrier to nitrate penetration in zebrafish, which may lead to conservative estimates of significant effects in other species for which nitrate more readily penetrates the chorion.

Elevated mitochondrial SLC25A29 in cancer modulates metabolic status by increasing mitochondria-derived nitric oxide

Warburg effect has been recognized as a hallmark of cancer cells for many years, but its modulation mechanism remains a great focus. Our current study found a member of solute carrier family 25 (SLC25A29), the main arginine transporter on mitochondria, significantly elevated in various cancer cells. Knockout of SLC25A29 by CRISPR/Cas9 inhibited proliferation and migration of cancer cells both in vitro and in vivo. SLC25A29-knockout cells also showed an altered metabolic status with enhanced mitochondrial respiration and reduced glycolysis. All of above impacts could be reversed after rescuing SLC25A29 expression in SLC25A29-knockout cells. Arginine is transported into mitochondria partly for nitric oxide (NO) synthesis. Deletion of SLC25A29 resulted in severe decrease of NO production, indicating that the mitochondria is a significant source of NO. SLC25A29-knockout cells dramatically altered the variation of metabolic processes, whereas addition of arginine failed to reverse the effect, highlighting the necessity of transporting arginine into mitochondria by SLC25A29. In conclusion, aberrant elevated SLC25A29 in cancer functioned to transport more arginine into mitochondria, improved mitochondria-derived NO levels, thus modulated metabolic status to facilitate increased cancer progression.

The Effect of Mitochondrial Complex I-Linked Respiration by Isoflurane Is Independent of Mitochondrial Nitric Oxide Production

BACKGROUND

Anesthetic preconditioning (APC) of the myocardium is mediated in part by reversible alteration of mitochondrial function. Nitric oxide (NO) inhibits mitochondrial respiration and may mediate APC-induced cardioprotection. In this study, the effects of isoflurane on different states of mitochondrial respiration during the oxidation of complex I-linked substrates and the role of NO were investigated.

METHODS

Mitochondria were isolated from Sprague-Dawley rat hearts. Respiration rates were measured polarographically at 28ºC with a computer-controlled Clark-type O2 electrode in the mitochondria (0.5 mg/mL) with complex I substrates glutamate/malate (5 mM). Isoflurane (0.25 mM) was administered before or after adenosine diphosphate (ADP)-initiated state 3 respiration. The NO synthase (NOS) inhibitor L-N5-(1-iminoethyl)-ornithine (L-NIO, 10 μM) and the NO donor S-nitroso-N-acetylpenicillamine (SNAP, 1 μM) were added before or after the addition of ADP.

RESULTS

Isoflurane administered in state 2 increased state 2 respiration and decreased state 3 respiration. This attenuation of state 3 respiration by isoflurane was similar when it was given during state 3. L-NIO did not alter mitochondrial respiration or the effect of isoflurane. SNAP only, added in state 3, decreased state 3 respiration and enhanced the isoflurane-induced attenuation of state 3 respiration.

CONCLUSION

Isoflurane has clearly distinguishable effects on different states of mitochondrial respiration during the oxidation of complex I substrates. The uncoupling effect during state 2 respiration and the attenuation of state 3 respiration may contribute to the mechanism of APC-induced cardioprotection. These effects of isoflurane do not depend on endogenous mitochondrial NO, as the NOS inhibitor L-NIO did not alter the effects of isoflurane on mitochondrial respiration.

Sex and nitric oxide bioavailability interact to modulate interstitial Po2 in healthy rat skeletal muscle

Premenopausal women express reduced blood pressure and risk of cardiovascular disease relative to age-matched men. This purportedly relates to elevated estrogen levels increasing nitric oxide synthase (NOS) activity and NO-mediated vasorelaxation. We tested the hypotheses that female rat skeletal muscle would: 1) evince a higher O₂ delivery-to-utilization ratio (Q̇o₂/V̇o₂) during contractions; and 2) express greater modulation of Q̇o₂/V̇o₂ with changes to NO bioavailability compared with male rats. The spinotrapezius muscle of Sprague-Dawley rats (females = 8, males = 8) was surgically exposed and electrically-stimulated (180 s, 1 Hz, 6 V). OxyphorG4 was injected into the muscle and phosphorescence quenching employed to determine the temporal profile of interstitial Po₂ (Po_2is, determined by Q̇o₂/V̇o₂). This was performed under three conditions: control (CON), 300 µM sodium nitroprusside (SNP; NO donor), and 1.5 mM N^ω-nitro-l-arginine methyl ester (l-NAME; NOS blockade) superfusion. No sex differences were found for the Po_2is kinetics parameters in CON or l-NAME ( P > 0.05), but females elicited a lower baseline following SNP (males 42 ± 3 vs. females 36 ± 2 mmHg, P < 0.05). Females had a lower ΔPo_2is during contractions following SNP (males 22 ± 3 vs. females 17 ± 2 mmHg, P < 0.05), but there were no sex differences for the temporal response to contractions ( P > 0.05). The total NO effect (SNP minus l-NAME) on Po_2is was not different between sexes. However, the spread across both conditions was shifted to a lower absolute range for females (reduced SNP baseline and greater reduction following l-NAME). These data support that females have a greater reliance on basal NO bioavailability and males have a greater responsiveness to exogenous NO and less responsiveness to reduced endogenous NO. NEW & NOTEWORTHY Interstitial Po₂ (Po_2is; determined by O₂ delivery-to-utilization matching) plays an important role for O₂ flux into skeletal muscle. We show that both sexes regulate Po_2is at similar levels at rest and during skeletal muscle contractions. However, modulating NO bioavailability exposes sex differences in this regulation with females potentially having a greater reliance on basal NO bioavailability and males having a greater responsiveness to exogenous NO and less responsiveness to reduced endogenous NO.

Interaction between Mitochondrial Reactive Oxygen Species, Heme Oxygenase, and Nitric Oxide Synthase Stimulates Phagocytosis in Macrophages

Background

Macrophages are cells of the innate immune system that populate every organ. They are required not only for defense against invading pathogens and tissue repair but also for maintenance of tissue homeostasis and iron homeostasis.

Aim

The aim of this study is to understand whether heme oxygenase (HO) and nitric oxide synthase (NOS) contribute to the regulation of nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity and phagocytosis, two key components of macrophage function.

Methods

This study was carried out using resting J774A.1 macrophages treated with hemin or vehicle. Activity of NOS, HO, or NOX was inhibited using specific inhibitors. Reactive oxygen species (ROS) formation was determined by Amplex^® red assay, and phagocytosis was measured using fluorescein isothiocyanate-labeled bacteria. In addition, we analyzed the fate of the intracellular heme by using electron spin resonance.

Results

We show that both enzymes NOS and HO are essential for phagocytic activity of macrophages. NOS does not directly affect phagocytosis, but stimulates NOX activity via nitric oxide-triggered ROS production of mitochondria. Treatment of macrophages with hemin results in intracellular accumulation of ferrous heme and an inhibition of phagocytosis. In contrast to NOS, HO products, including carbon monoxide, neither clearly affect NOX activity nor clearly affect phagocytosis, but phagocytosis is accelerated by HO-mediated degradation of heme.

Conclusion

Both enzymes contribute to the bactericidal activity of macrophages independently, by controlling different pathways.

Enhanced cerebral perfusion during brief exposures to cyclic intermittent hypoxemia

Cerebral vasodilation and increased cerebral oxygen extraction help maintain cerebral oxygen uptake in the face of hypoxemia. This study examined cerebrovascular responses to intermittent hypoxemia in eight healthy men breathing 10% O2 for 5 cycles, each 6 min, interspersed with 4 min of room air breathing. Hypoxia exposures raised heart rate ( P < 0.01) without altering arterial pressure, and increased ventilation ( P < 0.01) by expanding tidal volume. Arterial oxygen saturation ([Formula: see text]) and cerebral tissue oxygenation ([Formula: see text]) fell ( P < 0.01) less appreciably in the first bout (from 97.0 ± 0.3% and 72.8 ± 1.6% to 75.5 ± 0.9% and 54.5 ± 0.9%, respectively) than the fifth bout (from 94.9 ± 0.4% and 70.8 ± 1.0% to 66.7 ± 2.3% and 49.2 ± 1.5%, respectively). Flow velocity in the middle cerebral artery ( VMCA) and cerebrovascular conductance increased in a sigmoid fashion with decreases in [Formula: see text] and [Formula: see text]. These stimulus-response curves shifted leftward and upward from the first to the fifth hypoxia bouts; thus, the centering points fell from 79.2 ± 1.4 to 74.6 ± 1.1% ( P = 0.01) and from 59.8 ± 1.0 to 56.6 ± 0.3% ( P = 0.002), and the minimum VMCA increased from 54.0 ± 0.5 to 57.2 ± 0.5 cm/s ( P = 0.0001) and from 53.9 ± 0.5 to 57.1 ± 0.3 cm/s ( P = 0.0001) for the [Formula: see text]- VMCA and [Formula: see text]- VMCA curves, respectively. Cerebral oxygen extraction increased from prehypoxia 0.22 ± 0.01 to 0.25 ± 0.02 in minute 6 of the first hypoxia bout, and remained elevated between 0.25 ± 0.01 and 0.27 ± 0.01 throughout the fifth hypoxia bout. These results demonstrate that cerebral vasodilation combined with enhanced cerebral oxygen extraction fully compensated for decreased oxygen content during acute, cyclic hypoxemia.

NEW & NOTEWORTHY Five bouts of 6-min intermittent hypoxia (IH) exposures to 10% O2 progressively reduce arterial oxygen saturation ([Formula: see text]) to 67% without causing discomfort or distress. Cerebrovascular responses to hypoxemia are dynamically reset over the course of a single IH session, such that threshold and saturation for cerebral vasodilations occurred at lower [Formula: see text] and cerebral tissue oxygenation ([Formula: see text]) during the fifth vs. first hypoxia bouts. Cerebral oxygen extraction is augmented during acute hypoxemia, which compensates for decreased arterial O2 content.

The low affinity neurotensin receptor antagonist levocabastine impairs brain nitric oxide synthesis and mitochondrial function by independent mechanisms

Neurotensin is known to inhibit neuronal Na⁺ , K⁺ -ATPase, an effect that is rescued by nitric oxide (NO) synthase inhibition. However, whether the neurotensinergic and the nitrergic systems are independent pathways, or are mechanistically linked, remains unknown. Here, we addressed this issue and found that the administration of low affinity neurotensin receptor (NTS2) antagonist, levocabastine (50 μg/kg, i.p.) inhibited NO synthase (NOS) activity by 74 and 42% after 18 h in synaptosomal and mitochondrial fractions isolated from the Wistar rat cerebral cortex, respectively; these effects disappeared 36 h after levocabastine treatment. Intriguingly, whereas neuronal NOS protein abundance decreased (by 56%) in synaptosomes membranes, it was enhanced (by 86%) in mitochondria 18 h after levocabastine administration. Levocabastine enhanced the respiratory rate of synaptosomes in the presence of oligomycin, but it failed to alter the spare respiratory capacity; furthermore, the mitochondrial respiratory chain (MRC) complexes I-IV activities were severely diminished by levocabastine administration. The inhibition of NOS and MRC complexes activities were also observed after incubation of synaptosomes and mitochondria with levocabastine (1 μM) in vitro. These data indicate that the NTS2 antagonist levocabastine regulates NOS expression and activity at the synapse, suggesting an interrelationship between the neurotensinergic and the nitrergic systems. However, the bioenergetics effects of NTS2 activity inhibition are likely to be independent from the regulation of NO synthesis.

Recent developments in d-α-tocopheryl polyethylene glycol-succinate-based nanomedicine for cancer therapy

Cancer remains an obstacle to be surmounted by humans. As an FDA-approved biocompatible drug excipient, d-α-tocopheryl polyethylene glycol succinate (TPGS) has been widely applied in drug delivery system (DDS). Along with in-depth analyses of TPGS-based DDS, increasingly attractive results have revealed that TPGS is able to act not only as a simple drug carrier but also as an assistant molecule with various bio-functions to improve anticancer efficacy. In this review, recent advances in TPGS-based DDS are summarized. TPGS can inhibit P-glycoprotein, enhance drug absorption, induce mitochondrial-associated apoptosis or other apoptotic pathways, promote drug penetration and tumor accumulation, and even inhibit tumor metastasis. As a result, many formulations, by using original TPGS, TPGS-drug conjugates or TPGS copolymers, were prepared, and as expected, an enhanced therapeutic effect was achieved in different tumor models, especially in multidrug resistant and metastatic tumors. Although the mechanisms by which TPGS participates in such functions are not yet very clear, considering its effectiveness in tumor treatment, TPGS-based DDS appears to be one of the best candidates for future clinical applications.

T cells display mitochondria hyperpolarization in human type 1 diabetes

T lymphocytes constitute a major effector cell population in autoimmune type 1 diabetes. Despite essential functions of mitochondria in regulating activation, proliferation, and apoptosis of T cells, little is known regarding T cell metabolism in the progression of human type 1 diabetes. In this study, we report, using two independent cohorts, that T cells from patients with type 1 diabetes exhibited mitochondrial inner-membrane hyperpolarization (MHP). Increased MHP was a general phenotype observed in T cell subsets irrespective of prior antigen exposure, and was not correlated with HbA1C levels, subject age, or duration of diabetes. Elevated T cell MHP was not detected in subjects with type 2 diabetes. T cell MHP was associated with increased activation-induced IFNγ production, and activation-induced IFNγ was linked to mitochondria-specific ROS production. T cells from subjects with type 1 diabetes also exhibited lower intracellular ATP levels. In conclusion, intrinsic mitochondrial dysfunction observed in type 1 diabetes alters mitochondrial ATP and IFNγ production; the latter is correlated with ROS generation. These changes impact T cell bioenergetics and function.

Nitric Oxide and Related Aspects Underlying Angina

Increased number of patients affected by metabolic syndrome (MS) has prompted the necessity of better understanding what is involved in such syndrome. Nevertheless, the establishment of promising therapies depends on the knowledge about the interaction of molecules within MS. In such context, Nitric Oxide (NO) emerges from a bulk of works relating its roles on aspects of MS, including cardiovascular diseases, their symptoms and comorbidities, which are thought to be triggered by similar sources. NO, nitric oxide synthase and enzymatic chains are keys for those disease and symptoms processes. NO has been separately described as part of hypertensive, ischemic and pain signaling. Although there are similar pathways likely shared for generating cardiovascular symptoms such angina, they are barely associated to NO in literature. The present review aims to clarify the patterns of NO alteration in metabolic syndrome directly concerned to cardiovascular symptoms, especially angina.

Mitochondrial and endoplasmic reticulum dysfunction and related defense mechanisms in critical illness-induced multiple organ failure

Patients with critical illness-induced multiple organ failure suffer from a very high morbidity and mortality, despite major progress in intensive care. The pathogenesis of this condition is complex and incompletely understood. Inadequate tissue perfusion and an overwhelming inflammatory response with pronounced cellular damage have been suggested to play an important role, but interventions targeting these disturbances largely failed to improve patient outcome. Hence, new therapeutic perspectives are urgently needed. Cellular dysfunction, hallmarked by mitochondrial dysfunction and endoplasmic reticulum stress, is increasingly recognized as an important contributor to the development of organ failure in critical illness. Several cellular defense mechanisms are normally activated when the cell is in distress, but may fail or respond insufficiently to critical illness. This insight may open new therapeutic options by stimulating these cellular defense mechanisms. This review summarizes the current understanding of the role of mitochondrial dysfunction and endoplasmic reticulum stress in critical illness-induced multiple organ failure and gives an overview of the corresponding cellular defense mechanisms. Therapeutic perspectives based on these cellular defense mechanisms are discussed. This article is part of a Special Issue entitled: Immune and Metabolic Alterations in Trauma and Sepsis edited by Dr. Raghavan Raju.

Muscle atrophy is associated with cervical spinal motoneuron loss in BACHD mouse model for Huntington's disease

Involuntary choreiform movements are clinical hallmark of Huntington's disease, an autosomal dominant neurodegenerative disorder caused by an increased number of CAG trinucleotide repeats in the huntingtin gene. Involuntary movements start with an impairment of facial muscles and then affect trunk and limbs muscles. Huntington's disease symptoms are caused by changes in cortex and striatum neurons induced by mutated huntingtin protein. However, little is known about the impact of this abnormal protein in spinal cord motoneurons that control movement. Therefore, in this study we evaluated abnormalities in the motor unit (spinal cervical motoneurons, motor axons, neuromuscular junctions and muscle) in a mouse model for Huntington's disease (BACHD). Using light, fluorescence, confocal, and electron microscopy, we showed significant changes such as muscle fibers atrophy, fragmentation of neuromuscular junctions, axonal alterations, and motoneurons death in BACHD mice. Noteworthy, the surviving motoneurons from BACHD spinal cords were smaller than WT. We suggest that this loss of larger putative motoneurons is accompanied by a decrease in the expression of fast glycolytic muscle fibers in this model for Huntington's disease. These observations show spinal cord motoneurons loss in BACHD that might help to understand neuromuscular changes in Huntington's disease.