Changes In Mitochondrial Function Research Articles

Assessing the Association of Mitochondrial Function and Inflammasome Activation in Murine Macrophages Exposed to Select Mitotoxic Tri-Organotin Compounds.

Background:Mitochondrial function is implicated as a target of environmental toxicants and found in disease or injury models, contributing to acute and chronic inflammation. One mechanism by which mitochondrial damage can propagate inflammation is via activation of the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family, pyrin domain-containing receptor (NLRP)3 inflammasome, a protein complex that processes mature interleukin . plays an important role in the innate immune response and dysregulation is associated with autoinflammatory disorders.Objective:The objective was to evaluate whether mitochondrial toxicants recruit inflammasome activation and processing.Method:Murine macrophages (RAW 264.7) exposed to tri-organotins (triethyltin bromide (TETBr), trimethyltin hydroxide (TMTOH), triphenyltin hydroxide (TPTOH), bis(tributyltin)oxide) [Bis(TBT)Ox] were examined for pro-inflammatory cytokine induction. TMTOH and TETBr were examined in RAW 264.7 and bone marrow-derived macrophages for mitochondrial bioenergetics, reactive oxygen species (ROS) production, and inflammasome activation via visualization of aggregate formation, caspase-1 flow cytometry, enzyme-linked immunosorbent assay and Western blots, and microRNA (miRNA) and mRNA arrays.Results:TETBr and TMTOH induced inflammasome aggregate formation and release in lipopolysaccharide (LPS)-primed macrophages. Mitochondrial bioenergetics and mitochondrial ROS were suppressed. Il1a and Il1b induction with LPS or challenge was diminished. Differential miRNA and mRNA profiles were observed. Lower miR-151-3p targeted cyclic adenosine monophosphate (cAMP)-mediated and AMP-activated protein kinase signaling pathways; higher miR-6909-5p, miR-7044-5p, and miR-7686-5p targeted Wnt beta-catenin signaling, retinoic acid receptor activation, apoptosis, signal transducer and activator of transcription 3, IL-22, IL-12, and IL-10 signaling. Functional enrichment analysis identified apoptosis and cell survival canonical pathways.Conclusion:Select mitotoxic tri-organotins disrupted murine macrophage transcriptional response to LPS, yet triggered inflammasome activation. The differential response pattern suggested unique functional changes in the inflammatory response that may translate to suppressed host defense or prolong inflammation. We posit a framework to examine immune cell effects of environmental mitotoxic compounds for adverse health outcomes. https://doi.org/10.1289/EHP8314

Metabolic and behavioral features of acute hyperpurinergia and the maternal immune activation mouse model of autism spectrum disorder.

Since 2012, studies in mice, rats, and humans have suggested that abnormalities in purinergic signaling may be a final common pathway for many genetic and environmental causes of autism spectrum disorder (ASD). The current study in mice was conducted to characterize the bioenergetic, metabolomic, breathomic, and behavioral features of acute hyperpurinergia triggered by systemic injection of the purinergic agonist and danger signal, extracellular ATP (eATP). Responses were studied in C57BL/6J mice in the maternal immune activation (MIA) model and controls. Basal metabolic rates and locomotor activity were measured in CLAMS cages. Plasma metabolomics measured 401 metabolites. Breathomics measured 98 volatile organic compounds. Intraperitoneal eATP dropped basal metabolic rate measured by whole body oxygen consumption by 74% ± 6% (mean ± SEM) and rectal temperature by 6.2˚ ± 0.3˚C in 30 minutes. Over 200 metabolites from 37 different biochemical pathways where changed. Breathomics showed an increase in exhaled carbon monoxide, dimethylsulfide, and isoprene. Metabolomics revealed an acute increase in lactate, citrate, purines, urea, dopamine, eicosanoids, microbiome metabolites, oxidized glutathione, thiamine, niacinamide, and pyridoxic acid, and decreased folate-methylation-1-carbon intermediates, amino acids, short and medium chain acyl-carnitines, phospholipids, ceramides, sphingomyelins, cholesterol, bile acids, and vitamin D similar to some children with ASD. MIA animals were hypersensitive to postnatal exposure to eATP or poly(IC), which produced a rebound increase in body temperature that lasted several weeks before returning to baseline. Acute hyperpurinergia produced metabolic and behavioral changes in mice. The behaviors and metabolic changes produced by ATP injection were associated with mitochondrial functional changes that were profound but reversible.

Excessive exercise training causes mitochondrial functional impairment and decreases glucose tolerance in healthy volunteers

Exercise training positively affects metabolic health through increased mitochondrial oxidative capacity and improved glucose regulation and is the first line of treatment in several metabolic diseases. However, the upper limit of the amount of exercise associated with beneficial therapeutic effects has not been clearly identified. Here, we used a training model with a progressively increasing exercise load during an intervention over 4weeks. We closely followed changes in glucose tolerance, mitochondrial function and dynamics, physical exercise capacity, and whole-body metabolism. Following the week with the highest exercise load, we found a striking reduction in intrinsic mitochondrial function that coincided with a disturbance in glucose tolerance and insulin secretion. We also assessed continuous blood glucose profiles in world-class endurance athletes and found that they had impaired glucose control compared with a matched control group.

Mitochondrial dysfunction and mitophagy pathway activation in hepatitis E virus-infected livers of Mongolian gerbils

Recently, hepatitis E virus (HEV) has caused large outbreaks and presented a significant public health problem. Thus, the mechanism of HEV has attracted increasing research attention. Previous studies revealed that HEV infection induced hepatocyte injuries and structural and functional changes in mitochondria. These pathological changes affected the life cycle of hepatocytes. However, the precise underlying mechanism and the effector protein responsible for this process remain unclear. In the present study, mitochondrial function and the expression of mitophagy-associated mRNA transcripts and proteins were detected in an HEV- infected Mongolian gerbil model. Observation of ultrastructural changes in the liver of the inoculated group revealed the disappearance of mitochondrial cristae of mitochondrion, blurring of the bilayer structure and cavitation in the cytoplasm. The results showed that the mitochondrial transmembrane potential of decreased, mitochondrial transition pore (MPTP) opening increased, reactive oxygen species (ROS) production increased, and glutathione peroxidase (GSH-Px) activity decreased in the HEV-inoculated group. Moreover, the LC3, Beclin1, BNIP3L, Parkin, PINK1 and P62 mRNA levels were significantly increased (p < 0.05 and p < 0.01) in the inoculated group. Western blot and immunohistochemistry assay analyses detected the upregulation of the mitophagy-associated proteins LC3, Beclin1, BNIP3L, Parkin, PINK1 and P62 (p < 0.05 and p < 0.01) in HEV-infected gerbils. All these data demonstrated that HEV infection in vivo induced mitochondrial dysfunction and the activation of the mitophagy pathway, which might be one of the key factors in hepatocyte injury.

Correction of mitochondrial dysfunction by succinic acid derivatives under experimental cerebral ischemia conditions

Abstract The aim of the study. To evaluate the effect of succinic acid derivatives on changes of mitochondrial function in rats under cerebral ischemia conditions. Materials and methods. In this work, the effect of succinic acid, ethylmethylhydroxypyridine succinate, and acetylaminosuccinic acid at doses of 50 mg/kg, 100 mg/kg, and 200 mg/kg (per os) on the change of the neuronal mitochondria function was studied. Cerebral ischemia was reproduced by the Tamura method. The following parameters were evaluated: changes in aerobic/anaerobic metabolism, mitochondrial membrane potential, the opening rate of the mitochondrial pore of transitional permeability and the activity of apoptotic systems. Results. During the study, it was found that the use of the test-compounds at doses of 100 mg/kg and 200 mg/kg contributed to an increase in ATP-generating activity, as well as the maximum respiration level and respiratory capacity, while accompanied by a decrease in the intensity of anaerobic metabolism reactions. Also, upon administration of the test succinic acid derivatives, an increase in the mitochondrial membrane potential and latent opening time of the mitochondrial pore transitional permeability were observed. Moreover, the activity of caspase-3 and apoptosis-inducing factor on groups treated by test objects at doses of 100 mg/kg and 200 mg/kg was significantly lower than that in untreated animals. Conclusion. The studied succinic acid derivatives contribute to the restoration of mitochondrial function in cerebral ischemia conditions, while the most effective dose can be considered to be 100 mg/kg.

Apoptosis in resistance arteries induced by hydrogen peroxide: greater resilience of endothelium versus smooth muscle.

Reactive oxygen species (ROS) are implicated in cardiovascular and neurologic disorders including atherosclerosis, heart attack, stroke, and traumatic brain injury. Although oxidative stress can lead to apoptosis of vascular cells, such findings are largely based upon isolated vascular smooth muscle cells (SMCs) and endothelial cells (ECs) studied in culture. Studying intact resistance arteries, we have focused on understanding how SMCs and ECs in the blood vessel wall respond to acute oxidative stress induced by hydrogen peroxide, a ubiquitous, membrane-permeant ROS. We find that apoptosis induced by H2O2 is far greater in SMCs compared to ECs. For both cell types, apoptosis is associated with a rise in intracellular calcium concentration ([Ca2+]i) during H2O2 exposure. Consistent with their greater death, the rise in [Ca2+]i for SMCs exceeds that in ECs. Finding that disruption of the endothelium increases SMC death, we address how myoendothelial coupling and paracrine signaling attenuate apoptosis. Remarkably, conditions associated with chronic oxidative stress (advanced age, Western-style diet) protect SMCs during H2O2 exposure, as does female sex. In light of intracellular Ca2+ handling, we consider how glycolytic versus oxidative pathways for ATP production and changes in mitochondrial structure and function impact cellular resilience to H2O2-induced apoptosis. Gaining new insight into protective signaling within and between SMCs and ECs of the arterial wall can be applied to promote vascular cell survival (and recovery of blood flow) in tissues subjected to acute oxidative stress as occurs during reperfusion following myocardial infarction and thrombotic stroke.

Developmental programming: Metabolic tissue-specific changes in endoplasmic reticulum stress, mitochondrial oxidative and telomere length status induced by prenatal testosterone excess in the female sheep

Prenatal testosterone (T) excess-induced metabolic dysfunctions involve tissue specific changes in insulin sensitivity with insulin resistant, oxidative and lipotoxic state in liver/muscle and insulin sensitive but inflammatory and oxidative state in visceral adipose tissues (VAT). We hypothesized that mitochondrial dysfunction, endoplasmic reticulum (ER) stress and premature cellular senescence are contributors to the tissue-specific changes in insulin sensitivity. Markers of mitochondrial number, function, and oxidative phosphorylation (OxPhos), ER stress and cellular senescence (telomere length) were assessed in liver, muscle and 4 adipose (VAT, subcutaneous [SAT], epicardiac [ECAT] and perirenal [PRAT]) depots collected from control and prenatal T-treated female sheep at 21 months of age. Prenatal T treatment led to: (a) reduction in mitochondrial number and OxPhos complexes and increase in ER stress markers in muscle; (b) increase in fibrosis with trend towards increase in short telomere fragments in liver (c) depot-specific mitochondrial changes with OxPhos complexes namely increase in SAT and reduction in PRAT and increase in mitochondrial number in ECAT; (d) depot-specific ER stress marker changes with increase in VAT, reduction in SAT, contrasting changes in ECAT and no changes in PRAT; and (d) reduced shorter telomere fragments in SAT, ECAT and PRAT. These changes indicate insulin resistance may be driven by mitochondrial and ER dysfunction in muscle, fibrosis and premature senescence in liver, and depot-specific changes in mitochondrial function and ER stress without involving cellular senescence in adipose tissue. These findings provide mechanistic insights into pathophysiology of metabolic dysfunction among female offspring from hyperandrogenic pregnancies.

Mitochondria-cytokine crosstalk following skeletal muscle injury and disuse: a mini-review.

Skeletal muscle mitochondria are highly adaptable, highly dynamic organelles that maintain the functional integrity of the muscle fiber by providing ATP for contraction and cellular homeostasis (e.g., Na+/K+ ATPase). Emerging as early modulators of inflammation, mitochondria sense and respond to cellular stress. Mitochondria communicate with the environment, in part, by release of physical signals called mitochondrial-derived damage-associated molecular patterns (mito-DAMPs) and deviation from routine function (e.g., reduced ATP production, Ca2+ overload). When skeletal muscle is compromised, mitochondria contribute to an acute inflammatory response necessary for myofibril regeneration; however, exhaustive signaling associated with altered or reduced mitochondrial function can be detrimental to muscle outcomes. Here, we describe changes in mitochondrial content, structure, and function following skeletal muscle injury and disuse and highlight the influence of mitochondria-cytokine crosstalk on muscle regeneration and recovery. Although the appropriate therapeutic modulation following muscle stressors remains unknown, retrospective gene expression analysis reveals that interleukin-6 (IL-6), interleukin-1β (IL-1β), chemokine C-X-C motif ligand 1 (CXCL1), and monocyte chemoattractant protein 1 (MCP-1) are significantly upregulated following three unique muscle injuries. These cytokines modulate mitochondrial function and execute bona fide pleiotropic roles that can aid functional recovery of muscle, however, when aberrant, chronically disrupt healing partly by exacerbating mitochondrial dysfunction. Multidisciplinary efforts to delineate the opposing regulatory roles of inflammatory cytokines in the muscle mitochondrial environment are required to modulate regenerative behavior following skeletal muscle injury or disuse. Future therapeutic directions to consider include quenching or limited release of mito-DAMPs and cytokines present in cytosol or circulation.

Effects of Ultramarathon Running on Mitochondrial Function of Platelets and Oxidative Stress Parameters: A Pilot Study.

Only a few studies have evaluated changes in mitochondrial function and oxidative stress associated with ultramarathon running. Invasive biopsies are needed to assess mitochondrial function of skeletal muscle, which may not be well tolerated by some individuals. Platelets (PLTs) as a metabolically highly active and homogenous cell population were suggested as a potentially valuable surrogate to investigate mitochondrial function. Thus, this study was aimed to evaluate mitochondrial function of PLTs and its association with individual race performance and markers of oxidative stress, muscle damage and renal dysfunction. Race performance and mitochondrial function (high-resolution respirometry, HRR) of PLTs using different substrates inducing ROUTINE, LEAK, N-pathway control state (Complex I linked oxidative phosphorylation; CI, OXPHOS), NS-pathway control state (CI + II linked OXPHOS and electron transfer pathway; ET), S-pathway control state (CII linked ET) as well as parameters of oxidative stress and antioxidant capacity, and markers of muscle and renal injury were assessed in eight male ultramarathon runners (26–45 years) before, immediately after and 24 h after an ultramarathon race (PRE, POST, and REC). Ultramarathon running induced an increase in LEAK O2 flux of PLT mitochondria and slight, largely non-significant changes in the oxidant/antioxidant balance. Levels of creatine kinase (CK), lactate dehydrogenase (LDH), blood urea nitrogen, and creatinine were all significantly elevated POST and remained high in REC. There were inverse correlations between race time and N-linked substrate state PRE-POST, and changes in CK and LDH levels were significantly related to PLT mitochondrial LEAK and N-linked respiration PRE. Although race-related changes in respirometry parameters of PLT mitochondria were rather small, a somewhat more pronounced increase in the relative N-linked respiration in faster runners might suggest PLT CI as indicator of physical fitness. The higher PLT LEAK PRE and diminished increase of CK during the race may represent a prophylactic preconditioning and the slight but non-significant elevation of the antioxidant potential post-race as a protective consequence of the race-related oxidative stress and potential threat to the kidney. Our findings point toward an interrelationship between mitochondrial function of PLTs, individual fitness levels and extreme physical and metal stresses, which stimulates further research.

Atorvastatin impairs liver mitochondrial function in obese G\xf6ttingen Minipigs but heart and skeletal muscle are not affected

Statins lower the risk of cardiovascular events but have been associated with mitochondrial functional changes in a tissue-dependent manner. We investigated tissue-specific modifications of mitochondrial function in liver, heart and skeletal muscle mediated by chronic statin therapy in a Göttingen Minipig model. We hypothesized that statins enhance the mitochondrial function in heart but impair skeletal muscle and liver mitochondria. Mitochondrial respiratory capacities, citrate synthase activity, coenzyme Q10 concentrations and protein carbonyl content (PCC) were analyzed in samples of liver, heart and skeletal muscle from three groups of Göttingen Minipigs: a lean control group (CON, n = 6), an obese group (HFD, n = 7) and an obese group treated with atorvastatin for 28 weeks (HFD + ATO, n = 7). Atorvastatin concentrations were analyzed in each of the three tissues and in plasma from the Göttingen Minipigs. In treated minipigs, atorvastatin was detected in the liver and in plasma. A significant reduction in complex I + II-supported mitochondrial respiratory capacity was seen in liver of HFD + ATO compared to HFD (P = 0.022). Opposite directed but insignificant modifications of mitochondrial respiratory capacity were seen in heart versus skeletal muscle in HFD + ATO compared to the HFD group. In heart muscle, the HFD + ATO had significantly higher PCC compared to the HFD group (P = 0.0323). In the HFD group relative to CON, liver mitochondrial respiration decreased whereas in skeletal muscle, respiration increased but these changes were insignificant when normalizing for mitochondrial content. Oral atorvastatin treatment in Göttingen Minipigs is associated with a reduced mitochondrial respiratory capacity in the liver that may be linked to increased content of atorvastatin in this organ.

Mitochondrial Kinases and the Role of Mitochondrial Protein Phosphorylation in Health and Disease.

The major role of mitochondria is to provide cells with energy, but no less important are their roles in responding to various stress factors and the metabolic changes and pathological processes that might occur inside and outside the cells. The post-translational modification of proteins is a fast and efficient way for cells to adapt to ever changing conditions. Phosphorylation is a post-translational modification that signals these changes and propagates these signals throughout the whole cell, but it also changes the structure, function and interaction of individual proteins. In this review, we summarize the influence of kinases, the proteins responsible for phosphorylation, on mitochondrial biogenesis under various cellular conditions. We focus on their role in keeping mitochondria fully functional in healthy cells and also on the changes in mitochondrial structure and function that occur in pathological processes arising from the phosphorylation of mitochondrial proteins.

Listeria monocytogenes upregulates mitochondrial calcium signalling to inhibit LC3-associated phagocytosis as a survival strategy.

Mitochondria are believed to have originated ~2.5 billion years ago. As well as energy generation in cells, mitochondria have a role in defence against bacterial pathogens. Despite profound changes in mitochondrial morphology and functions following bacterial challenge, whether intracellular bacteria can hijack mitochondria to promote their survival remains elusive. We report that Listeria monocytogenes-an intracellular bacterial pathogen-suppresses LC3-associated phagocytosis (LAP) by modulation of mitochondrial Ca2+ (mtCa2+) signalling in order to survive inside cells. Invasion of macrophages by L. monocytogenes induced mtCa2+ uptake through the mtCa2+ uniporter (MCU), which in turn increased acetyl-coenzyme A (acetyl-CoA) production by pyruvate dehydrogenase. Acetylation of the LAP effector Rubicon with acetyl-CoA decreased LAP formation. Genetic ablation of MCU attenuated intracellular bacterial growth due to increased LAP formation. Our data show that modulation of mtCa2+ signalling can increase bacterial survival inside cells, and highlight the importance of mitochondrial metabolism in host-microbial interactions.

Muscle fiber type specific alterations of mitochondrial respiratory function and morphology in aged female mice

Mitochondrial dysfunction is considered to be a major cause of sarcopenia, defined as age-related muscle fiber atrophy and muscle weakness, as reduced mitochondrial respiration and morphological changes such as ragged red fibers (RRFs) are observed in aging muscles. However, the role of mitochondrial dysfunction in sarcopenia is not fully elucidated. Although previous studies have suggested that aging has a fiber type-specific effect on mitochondrial function, little is known about mitochondrial changes in individual fiber types. Here, we used C57BL/6NCr female mice to identify fiber type-specific pathological changes, examine the significance of pathological changes in sarcopenia, and identify possible mechanisms behind mitochondrial changes in slow-twitch soleus muscle (SOL) and fast-twitch extensor digitorum longus muscle (EDL). We observed reduced type I fiber-specific mitochondrial respiratory enzyme activity, impaired respiration, and subsarcolemmal mitochondrial accumulation in aged SOL, which was different from RRFs. These pathological alterations were not directly associated with fiber atrophy. Additionally, we found increased oxidative stress markers in aged SOL, suggesting that oxidative stress is involved in the pathological and functional changes in mitochondria. Meanwhile, obvious mitochondrial changes were not seen in aged EDL. Thus, age-related mitochondrial dysfunction is specific to the fiber type and may correlate with the muscle quality rather than the muscle mass.

SIRT3-Mediated SOD2 and PGC-1α Contribute to Chemoresistance in Colorectal Cancer Cells.

Anticancer drugs generate excessive reactive oxygen species (ROS), which can cause cell death. Cancer cells can resist this oxidative stress, but the mechanism of resistance and associations with chemoresistance are unclear. Here, we focused on Sirtuin 3 (SIRT3), a deacetylating mitochondrial enzyme, in oxidative stress resistance in colorectal cancer (CRC). To evaluate SIRT3-related changes in mitochondrial function, ROS (mtROS) induction, and apoptosis, we used the human CRC cell lines HT29 and HCT116 transfected with short-hairpin RNA targeting SIRT3 and small interfering RNAs targeting superoxide dismutase 2 mitochondrial (SOD2) and peroxisome proliferator-activated receptor γ coactivator-1 (PGC-1α). In 142 clinical specimens from patients with CRC, we also assessed the association of SIRT3 protein levels (high/low) and prognosis. SIRT3 expression correlated with mtROS generation and apoptosis induction in cells treated with anticancer agents. Suppressing SIRT3 increased mtROS levels and cell sensitivity to anticancer agents. SIRT3 knockdown decreased SOD2 expression and activity, and suppressing SOD2 also improved sensitivity to anticancer drugs. In addition, SIRT3 was recruited with PGC-1α under oxidative stress, and suppressing SIRT3 decreased PGC-1α expression and mitochondrial function. PGC-1α knockdown decreased mitochondrial activity and increased apoptosis in cells treated with anticancer drugs. In resected CRC specimens, high vs low SIRT3 protein levels were associated with significantly reduced cancer-specific survival. SIRT3 expression affected CRC cell chemoresistance through SOD2 and PGC-1α regulation and was an independent prognostic factor in CRC. SIRT3 may be a novel target for CRC therapies and a predictive marker of sensitivity to chemotherapy.

Analysis of the Effects of Hexokinase 2 Detachment From Mitochondria-Associated Membranes with the Highly Selective Peptide HK2pep

The crucial role of hexokinase 2 (HK2) in the metabolic rewiring of tumors is now well established, which makes it a suitable target for the design of novel therapies. However, hexokinase activity is central to glucose utilization in all tissues; thus, enzymatic inhibition of HK2 can induce severe adverse effects. In an effort to find a selective anti-neoplastic strategy, we exploited an alternative approach based on HK2 detachment from its location on the outer mitochondrial membrane. We designed a HK2-targeting peptide named HK2pep, corresponding to the N-terminal hydrophobic domain of HK2 and armed with a metalloprotease cleavage sequence and a polycation stretch shielded by a polyanion sequence. In the tumor microenvironment, metalloproteases unleash polycations to allow selective plasma membrane permeation in neoplastic cells. HK2pep delivery induces the detachment of HK2 from mitochondria-associated membranes (MAMs) and mitochondrial Ca2+ overload caused by the opening of inositol-3-phosphate receptors on the endoplasmic reticulum (ER) and Ca2+ entry through the plasma membrane leading to Ca2+-mediated calpain activation and mitochondrial depolarization. As a result, HK2pep rapidly elicits death of diverse tumor cell types and dramatically reduces in vivo tumor mass. HK2pep does not affect hexokinase enzymatic activity, avoiding any noxious effect on non-transformed cells. Here, we make available a detailed protocol for the use of HK2pep and to investigate its biological effects, providing a comprehensive panel of assays to quantitate both HK2 enzymatic activity and changes in mitochondrial functions, Ca2+ flux, and cell viability elicited by HK2pep treatment of tumor cells. Graphical abstract: Flowchart for the analysis of the effects of HK2 detachment from MAMs.

Impact of intravenous iron on cardiac and skeletal oxidative stress and cardiac mitochondrial function in experimental uraemia chronic kidney disease.

Introuction: Uraemia leads to changes in cardiac structure, metabolic remodeling and anaemia, key factors in the development of heart failure in patients with chronic kidney disease. Previous studies have identified abnormalities in mitochondrial function, potentially impairing energy provision and enhancing oxidative stress. This study characterised oxidant status and changes in mitochondrial function in uraemia and the impact of correcting anaemia via intravenous iron therapy. Methods: Experimental uraemia was induced in male Sprague-Dawley rats via a subtotal nephrectomy and parenteral iron administration given 6 weeks post-surgery. Oxidative stress from tissue samples was evaluated by measuring pro-oxidant activities and anti-oxidant capacities in both sham and uraemic animals with and without iron supplementation. Thiobarbituric acid-reactive substances (TBARS), aconitase activity and cardiolipin were measured. Mitochondrial function was assessed using the Seahorse XFp analyser on isolated mitochondria excised from cardiac tissue. Results: Oxidative stress in this uraemic model was increased in cardiac tissue (increased GSSG/GSH ratio, TBARS and increased activities of pro-oxidant enzymes). There was no impact on skeletal tissue. Parenteral iron ameliorated oxidative stress by enhancing the anti-oxidant defense system in cardiac tissue and skeletal tissue. Examination of respiratory reserve in cardiac mitochondria demonstrated that parenteral iron restored mitochondrial function. This experimental model of uraemia demonstrated a specific oxidative stress on the heart muscle without significant changes in skeletal oxidant status. Iron therapy improved anti-oxidant defence system, consequently reducing oxidative stress in the heart and skeletal tissue. There was an improvement in cardiac mitochondrial function. Conclusions: This experimental evidence indicates that iron therapy could reduce vulnerability to oxidative stress and potentially improve both cardiac and skeletal functional capacity from improvements in mitochondrial function.

Nontuberculous mycobacteria induce mitochondrial dysfunction in macrophages

Aims and Objectives: The incidence of nontuberculous mycobacterial (NTM) disease continues to rise, especially in developed countries. While NTM can affect almost any organ system, pulmonary infection is more prevalent than disseminated disease and can occur in patients with COPD, non-cystic fibrosis (CF) bronchiectasis, and CF. Mitochondria are the powerhouse of the cell, but it is unknown what role they play in the host response to NTM infection. Using electron microscopy, we have previously shown that mitochondrial morphology is altered upon infection with Mycobacterium avium intracellulare (MAI). Thus, we hypothesize that mitochondrial damage leading to changes in mitochondrial function and dynamics impair host response to infection with MAI and Mycobacterium abscessus (MAB). Methods: We infected MH-S cells (murine alveolar macrophages) and bone marrow-derived macrophages (BMDM) with clinical strains of MAI or MAB (multiplicity of infection [MOI] of 25) for 6 and 24 hours. We determined the expression of mitochondrial DNA fragments mt79 and mt230 that are associated with mitochondrial DNA damage using RT-qPCR; we calculated the fold change of these fragments relative to GAPDH and determined a ratio of these fragments. We also determined the expression of key mitochondrial quality control genes, including peroxisome proliferator activated receptor gamma coactivator (PGC)-1α, transcription factor A mitochondrial (TFAM), and mitofusin (MFN)-2, using RT-qPCR. Results: We found that in MH-S cells, the mt79:mt230 ratio was increased at 6 and 24 hours for both MAI and MAB relative to controls infected with PBS. Furthermore, expression of genes involved in mitochondrial biogenesis, PGC-1 α and TFAM, were both decreased at 6 and 24 hours. MFN2 was also decreased at both 6 and 24 hours for MAI and MAB. These data were consistent in BMDM, with a more significant decrease in these genes noted at 24 hours. Conclusions: These data suggest that there is an increase in mitochondrial damage as indicated by the mt79:230 ratio when macrophages are infected with NTM. The infected macrophages exhibit decreased mitochondrial biogenesis and also have impaired mitochondrial quality control, including mitochondrial fusion and fission. The functional impact of these impaired mitochondria on host response to NTM infection needs to be further explored as there may be a role for pharmacologic interventions, like PGC-1 α activators, that can augment bacterial killing in patients infected with NTM.

Targeting the Mitochondrial Permeability Transition Pore to Prevent Age-Associated Cell Damage and Neurodegeneration.

The aging process is associated with significant alterations in mitochondrial function. These changes in mitochondrial function are thought to involve increased production of reactive oxygen species (ROS), which over time contribute to cell death, senescence, tissue degeneration, and impaired tissue repair. The mitochondrial permeability transition pore (mPTP) is likely to play a critical role in these processes, as increased ROS activates mPTP opening, which further increases ROS production. Injury and inflammation are also thought to increase mPTP opening, and chronic, low-grade inflammation is a hallmark of aging. Nicotinamide adenine dinucleotide (NAD+) can suppress the frequency and duration of mPTP opening; however, NAD+ levels are known to decline with age, further stimulating mPTP opening and increasing ROS release. Research on neurodegenerative diseases, particularly on Parkinson's disease (PD) and Alzheimer's disease (AD), has uncovered significant findings regarding mPTP openings and aging. Parkinson's disease is associated with a reduction in mitochondrial complex I activity and increased oxidative damage of DNA, both of which are linked to mPTP opening and subsequent ROS release. Similarly, AD is associated with increased mPTP openings, as evidenced by amyloid-beta (Aβ) interaction with the pore regulator cyclophilin D (CypD). Targeted therapies that can reduce the frequency and duration of mPTP opening may therefore have the potential to prevent age-related declines in cell and tissue function in various systems including the central nervous system.

Research trends, hot spots and prospects for necroptosis in the field of neuroscience.

There are two types of cell death-apoptosis and necrosis. Apoptosis is cell death regulated by cell signaling pathways, while necrosis has until recently been considered a passive mechanism of cell death caused by environmental pressures. However, recent studies show that necrosis can also be regulated by specific cell signaling pathways. This mode of death, termed necroptosis, has been found to be related to the occurrence and development of many diseases. We used bibliometrics to analyze the global output of literature on necroptosis in the field of neuroscience published in the period 2007-2019 to identify research hotspots and prospects. We included 145 necroptosis-related publications and 2239 references published in the Web of Science during 2007-2019. Visualization analysis revealed that the number of publications related to necroptosis has increased year by year, reaching a peak in 2019. China is the country with the largest number of publications. Key word and literature analyses demonstrated that mitochondrial function change, stroke, ischemia/reperfusion and neuroinflammation are likely the research hotspots and future directions of necroptosis research in the nervous system. The relationship between immune response-related factors, damage-associated molecular patterns, pathogen-associated molecular patterns and necroptosis may become a potential research hotspot in the future. Taken together, our findings suggest that although the inherent limitations of bibliometrics may affect the accuracy of the literature-based prediction of research hotspots, the results obtained from the included publications can provide a reference for the study of necroptosis in the field of neuroscience.

Rhein Activates Janus Protein Tyrosine Kinase2/Signal Transducer and Transcription Activation Factor3 Reduces Mitochondrial Oxidative Damage Caused by Myocardial Ischemia/Reperfusion Injury

Background: Rhein is a kind of lipophilic anthraquinone widely existing in herbal medicine. Here we aim to investigate whether Rhein can reduce the degree of myocardial ischemia/reperfusion injury and inhibit the development of oxidative stress, and elucidate the molecular mechanism of Rhein in protecting myocardial cells. Methods: The anti-oxidation and anti-apoptosis effects of Rhein were studied by using the primary myocardial cells of ischemia/reperfusion rat as the model of myocardial injury. Cell viability was detected by MTT, The level of LDH and CK-MB released by cardiomyocytes was measured by Colorimetric assay. The ROS was observed under microscope and the level of catalase and glutathione peroxidase were detected by enzymatic methods. The JAK2/STAT3 signaling pathway mediated by Rhein was observed by Western blot. Results: Compared with that of the SIR group, cell viability in the SIR and Rhein co-treatment groups increased significantly (P &lt; 0.001), the release of LDH and CK-MB decreased, the positive rate of ROS in cardiomyocytes decreased, and the concentration of catalase and glutathione peroxidase increased significantly (P &lt; 0.001). Besides, Rhein can activate JAK2/STAT3 signaling pathway. JAK2 siRNA can inhibit the JAK2/STAT3 signaling mediated by Rhein. The addition of Rhein can significantly increase the activity of mitochondrial superoxide dismutase (SOD) and reduce the MDA, which indicates that the oxidative damage of mitochondria induced by Rhein was significantly weakened. The mitochondrial functional changes induced by Rhein can be reversed by JAK2 siRNA. Conclusion: Our study shows that Rhein can reduce ROS in cardiomyocytes by JAK2/STAT3 signaling pathway activation, and effectively inhibit the apoptosis of cardiomyocytes, thus having a direct protective effect on cardiomyocytes under SIR.