Maximal Oxygen Consumption Rate Research Articles

Mitochondria as a Platform for Dictating the Cell Fate of Cultured Human Corneal Endothelial Cells.

PurposeAiming to clarify the role of mitochondria in cell fate decision of cultured human corneal endothelial cell (cHCEC) subpopulations.MethodsThe mitochondrial respiratory ability were examined with Mito stress and Mito fuel flex test assays using an extracellular flux analyzer (XFe24; Agilent Technologies; Santa Clara, CA) for human corneal endothelium tissues, mature cHCECs and a variety of cell state transitioned cHCECs. Tricarboxylic acid cycle and acetyl-coenzyme A–related enzymes was analyzed by proteomics for cell lysates using liquid chromatography–tandem mass spectrometry for cHCEC subpopulations.ResultsThe maximum oxygen consumption rate was found to become stable depending on the maturation of cHCECs. In the Mito stress tests, culture supplements, epidermal growth factor, SB203580, and SB431543 significantly repressed oxygen consumption rate, whereas a Rho-associated protein kinase inhibitor Y-27632 increased. Tricarboxylic acid cycle and mitochondria acetyl-coenzyme A–related enzymes were selectively upregulated in mature cHCECs, but not in cell state transitioned cHCECs. The maximum oxygen consumption rate was found to be higher in healthy human corneal endothelium tissues than those with deeply reduced cell density. An upregulated tricarboxylic acid cycle was linked with metabolic rewiring converting cHCECs to acquire the mitochondria-dependent oxidative phenotype.ConclusionsMitochondrial metabolic intermediates and energy metabolism are tightly linked to the endothelial cell fate and function. These findings will help us to standardize a protocol for endothelial cell injection.

Age-related fatigue is associated with reduced mitochondrial function in peripheral blood mononuclear cells.

Fatigue is a complex syndrome associated with exhaustion not relieved by sleep. It occurs frequently in older adults in the context of chronic disease and is associated with decreased physical capacity. Whether a mitochondrial dysfunction and therefore an impaired energy production might contribute to the development of fatigue during aging is yet unknown. The aim of this study was to evaluate mitochondrial respiration of peripheral blood mononuclear cells (PBMCs) in older patients with and without fatigue. Fatigue was determined according to the Brief Fatigue Inventory. Mitochondrial respiration of freshly isolated PBMCs was investigated by high-resolution respirometry using the Oroboros Oxygraph-O2k. Functional impairment and depressive symptoms were assessed using questionnaires. 23 geriatric patients (77.8±4.9years; 43.5% female) with fatigue and 22 without fatigue (75.4±5.4years; 45.5% female) were analyzed. Patients with fatigue exhibited more functional limitations and more depressive symptoms. High-resolution respirometry of intact PBMCs revealed a lower routine (4.82±1.14pmol/s versus 5.89±1.90pmol/s, p=0.041) and maximum (6.55±1.51pmol/s versus 8.43±3.67pmol/s, p=0.013) oxygen consumption rate, resulting in a reduced ATP-linked respiration (4.26±1.00pmol/s versus 5.09±1.53pmol/s, p=0.035) of PBMCs from geriatric patients with fatigue compared to controls without. This short report shows that in this group of older patients, fatigue is associated with lower PBMC mitochondrial respiration. Whether the impaired mitochondrial respiration is accompanied by a reduced mitochondrial activity in other organs (e.g. muscle) remains to be elucidated.

Microvascular Assessment of Ranolazine in Non-Obstructive Atherosclerosis: The MARINA Randomized, Double-Blinded, Controlled Pilot Trial.

Microvascular dysfunction is known to play a key role in patients with angina and nonobstructive coronary artery disease. We investigated the impact of ranolazine among patients with angina and nonobstructive coronary artery disease. In this randomized, double-blinded, placebo-controlled pilot trial, 26 patients with angina once weekly or more, abnormal stress test, and nonobstructive coronary artery disease (<50% stenosis by angiography and fractional flow reserve >0.80) were randomized 1:1 to ranolazine or placebo for 12 weeks. Primary end point was ΔSeattle Angina Questionnaire (SAQ) angina frequency score. Baseline and 3 months follow-up SAQ, Duke Activity Status Index scores along with invasive fractional flow reserve, coronary flow reserve (CFR), hyperemic myocardial resistance, and cardiopulmonary exercise testing measurements were performed. No significant differences in ΔSAQ angina frequency scores (P=0.53) or Duke Activity Status Index (P=0.76) were observed between ranolazine versus placebo, although patients on ranolazine had lesser improvement in SAQ physical limitation scores (P=0.02) compared with placebo at 3 months. There were no significant differences in ΔCFR or Δhyperemic myocardial resistance between ranolazine and placebo groups. Patients treated with ranolazine, compared with placebo, had no significant improvement in maximum rate of oxygen consumption measured during incremental exercise (VO2 max) and peak metabolic equivalents of task. Interestingly, in the ranolazine group, patients with baseline CFR<2.0 demonstrated greater gain in CFR compared with those with baseline CFR≥2.0 (P=0.02). Ranolazine did not demonstrate improvement in SAQ angina frequency score, invasive microvascular function, or peak metabolic equivalent compared with placebo at 3 months. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02147067.

Muscle Stem Cell-Derived Extracellular Vesicles Reverse Hydrogen Peroxide-Induced Mitochondrial Dysfunction in Mouse Myotubes.

Muscle stem cells (MuSCs) hold great potential as a regenerative therapeutic but have met numerous challenges in treating systemic muscle diseases. Muscle stem cell-derived extracellular vesicles (MuSC-EVs) may overcome these limitations. We assessed the number and size distribution of extracellular vesicles (EVs) released by MuSCs ex vivo, determined the extent to which MuSC-EVs deliver molecular cargo to myotubes in vitro, and quantified MuSC-EV-mediated restoration of mitochondrial function following oxidative injury. MuSCs released an abundance of EVs in culture. MuSC-EVs delivered protein cargo into myotubes within 2 h of incubation. Fluorescent labeling of intracellular mitochondria showed co-localization of delivered protein and mitochondria. Oxidatively injured myotubes demonstrated a significant decline in maximal oxygen consumption rate and spare respiratory capacity relative to untreated myotubes. Remarkably, subsequent treatment with MuSC-EVs significantly improved maximal oxygen consumption rate and spare respiratory capacity relative to the myotubes that were damaged but received no subsequent treatment. Surprisingly, MuSC-EVs did not affect mitochondrial function in undamaged myotubes, suggesting the cargo delivered is able to repair but does not expand the existing mitochondrial network. These data demonstrate that MuSC-EVs rapidly deliver proteins into myotubes, a portion of which co-localizes with mitochondria, and reverses mitochondria dysfunction in oxidatively-damaged myotubes.

Supervised Physical Therapy and Polymyositis/Dermatomyositis-A Systematic Review of the Literature.

Objective: to find the most up-to-date evidence of the effectiveness and safety of supervised physical therapy in polymyositis/dermatomyositis patients. Methods: a systematic review of the literature in the main scientific databases was carried out. We searched for randomized controlled trials concerning supervised physical therapy and polymyositis/dermatomyositis. The PICOS method was used for the formulation of the clinical query. Methodological quality and the level of evidence of the included studies were assessed using the modified Jadad scale and the Oxford Centre for Evidence-Based Medicine Levels of Evidence guide, respectively. Results: a total of 2591 articles were found. By applying the inclusion/exclusion criteria, six randomized controlled clinical trials were admitted to the final phase of the review. The compared approaches concerned supervised exercise programs based on strategies of muscle strengthening or aerobic work. Following these exercises, an increase in the maximum rate of oxygen consumption, a decrease in creatine phosphokinase levels, an enhancement in the patient’s aerobic performance and an improvement in the quality of life indexes were registered. The methodological quality of the included studies ranged from 3 to 4.5. All the studies were classified as presenting an evidence level of 2b. Conclusions: supervised physical therapy in polymyositis/dermatomyositis is an effective, safe and free-of-contraindications tool to be used both in the acute and in the established phases of the pathology. However, further and higher-quality studies are necessary to confirm those findings, to clarify the timing of exercise delivery and to guide the choice towards different types of muscle contraction exercises.

Increasing AMPK Activity in Human T Cells Enhances Memory Subset Formation without Sacrificing in Vitro Expansion

BACKGROUND: While chimeric antigen receptor (CAR)-T cell therapy has revolutionized the treatment of relapsed/refractory acute lymphoblastic leukemia (ALL), treatment failures continue to occur. In studying therapeutic T cell function, it has become clear that achieving a memory-like phenotype is ideal for CAR-T production. This is likely related to the enhanced oxidative metabolic potential of this subset, which allows for improved persistence and enhanced anti-leukemia activity in vivo. However, current expansion protocols drive T cells towards terminal differentiation, decreasing the number of T cells fit for the in vivo environment. Finding methods to improve the yield of memory-like cells without sacrificing T cell expansion has been challenging. AMP-activated protein kinase (AMPK) is a key metabolic regulator responsible for promoting mitochondrial biogenesis and oxidative metabolism, and is more active in memory T cells at baseline. It is similarly induced by TCR ligation, making it unlikely that it would significantly detract from proliferation. These properties make activation of AMPK a potential candidate pathway for improving the yield of more functional T cells for CAR-T cell therapy. METHODS: AMPK is a heterotrimeric protein complex consisting of alpha, beta, and gamma domains. Functionally, the alpha subunit contains the kinase domain, which is activated by phosphorylation. The gamma subunit controls the phosphorylation, and therefore the activity, of the alpha domain. To increase AMPK signaling in T cells, we cloned the gamma subunit into a lentiviral plasmid containing the elongation factor 1a (EF1a) promoter and a green fluorescent protein (GFP) tag. An empty vector, containing GFP only, served as a negative control. Human T cells were isolated from three separate donors, transduced with our lentiviral construct, and expanded in vitro in the presence of IL-2. AMPK activity was assessed by phosphorylation of Thr172 on the AMPKα subunit as well as phosphorylation of S555 on downstream target Unc-51-like autophagy activating kinase (ULK1) using western blot densitometry, normalized to the total protein amounts. Memory marker expression and mitochondrial density (using Mitotracker Red) were analyzed by flow cytometry. Oxidative metabolism and spare respiratory capacity (SRC) were determined using the Seahorse Metabolic Analyzer. Fold changes for in vitro expansion were calculated by adjusting manual cell counts to reflect GFP positivity and CD4+/CD8+ surface staining. RESULTS: The AMPK gamma subunit was efficiently transduced and expressed by human T cells as measured by GFP expression, qRT-PCR, and western blot analysis. Further, AMPK activity increased in GFP+ cells as indicated by the phosphorylation of AMPKα Thr172 (1.93 +/- 0.05 vs 0.6 +/- 0.09, p&amp;lt;0.001) and ULK1 S555 (1.28 +/- 0.11 vs 0.67 +/- 0.08, p&amp;lt;0.01). Cells transduced with AMPK augmented expression of memory markers CD62L, CD27, and CCR7, with an increased yield of stem cell memory-like T cells marked by co-expression of CD45RA and CD62L (Figure 1). In addition, AMPK-transduced T cells showed a statistically significant increase in mitochondrial density along with notable enhancement of SRC and maximal oxygen consumption rates (Figure 2A,B). Furthermore, the rate of expansion of AMPK-transduced T cells did not differ significantly from Empty-transduced controls, and in fact trended towards increased in both CD4+ and CD8+ cells (Figure 3A). Indeed, the improved rate of expansion in AMPK-transduced CD4+ T cells led to a measurable increase in CD4+ T cell percentages by flow cytometry (Figure 3B). DISCUSSION: Here we present an efficient and direct method to increase AMPK activity in human T cells and demonstrate that increased AMPK activity endows T cells with a variety of characteristics ideal for CAR-T cell therapy. These features include increased memory-marker expression, enhanced SRC and oxidative metabolism, equivalent to augmented in vitro expansion, and improved CD4+ T cell yields. Further studies are ongoing to assess the activity and function of AMPK-transduced CAR-T cells both in vitro and in vivo. Disclosures No relevant conflicts of interest to declare.

Effects of benthic hydraulics on sediment oxygen demand in a canyon-shaped deep drinking water reservoir: Experimental and modeling study

Sediment oxygen demand (SOD) is a major contributor to hypolimnetic oxygen depletion and the release of internal nutrient loading. By measuring the SOD in experimental chambers using in both dissolved oxygen (DO) depletion and diffusional oxygen transfer methods, a model of SOD for a sediment bed with water current-induced turbulence was presented. An experimental study was also performed using near-sediment vertical DO profiles and correlated hydraulic parameters stimulated using a computational fluid dynamics model to determine how turbulences and DO concentrations in the overlying water affects SOD and diffusive boundary layer thickness. The dependence of the oxygen transfer coefficient and diffusive boundary layer on hydraulic parameters was quantified, and the SOD was expressed as a function of the shear velocity and the bulk DO concentrations. Theoretical predictions were validated using microelectrode measurements in a series of laboratory experiments. This study found that flow over the sediment surface caused an increase in SOD, attributed to enhanced sediment oxygen uptake and reduced substances fluxes, i.e., for a constant maximum biological oxygen consumption rate, an increased current over the sediment could increase the SOD by 4.5 times compared to stagnant water. These results highlight the importance of considering current-induced SOD increases when designing and implementing aeration/artificial mixing strategies.

Translating Preclinical Research for Exercise Oncology: Take It to the VO2max.

Several observational studies have found that the risk for breast cancer is significantly reduced in persons who engage in greater amounts of physical activity. Additional observational studies of breast cancer survivors indicate that greater physical activity before or after diagnosis associates with reduced disease-specific mortality. However, no large randomized controlled trials have examined the effect of structured exercise training on disease outcomes in breast cancer. Among the many hurdles in designing such trials lies the challenge of determining how a given regimen of exercise from efficacious preclinical studies can be extrapolated to an equivalent “dose” in humans to guide decisions around treatment regimen in early-phase studies. We argue that preclinical researchers in exercise oncology could better facilitate this endeavor by routinely measuring changes in exercise capacity in the subjects of their breast cancer models. VO2max, the maximal rate of whole-organism oxygen consumption during a progressive exercise test, is emphasized here because it has become a standard measure of cardiorespiratory fitness, is well-integrated in clinical settings, and scales allometrically among nonhuman animals in preclinical research and breast cancer patients/survivors in the clinic. We also conduct secondary analyses of existing whole-transcriptome datasets to highlight how greater uptake and delivery of oxygen during exercise may reverse the typically hypoxic microenvironment of breast tumors, which often associates with more aggressive disease and worse prognosis.

Hunters versus hunted: New perspectives on the energetic costs of survival at the top of the food chain

Abstract Global biotic and abiotic threats, particularly from pervasive human activities, are progressively pushing large, apex carnivorous mammals into the functional role of mesopredator. Hunters are now becoming the hunted. Despite marked impacts on these animals and the ecosystems in which they live, little is known about the physiological repercussions of this role downgrading from ultimate to penultimate predator. Here we examine how such ecological role reversals alter the physiological processes associated with energy expenditure, and ultimately the cost of survival during peak performance. Taxonomic group, preferred habitat and domestication affected the capacity of the oxygen pathway to support high levels of aerobic performance by carnivorous mammals. Fear responses associated with anthropogenic threats also impacted aerobic performance. Allometric trends for three energetic metrics [maximum oxygen consumption, field metabolic rates (FMRs) and the cost per stride or stroke], showed distinct trends in aerobic capacity for different evolutionary lineages of mammalian predators. Cursorial canids that chase down prey demonstrated the highest relative maximum oxygen consumption rates (10–25 times resting levels) and FMRs, while ambush predators (i.e. felids) and diving marine mammals had aerobic capacities that were similar to or lower than sedentary domestic mammals of comparable size. The maximum energetic cost of performance for apex predators depended on whether the animals were hunters or the hunted. Escape responses were exceptionally costly for marine (narwhal Monodon monoceros) and terrestrial (mountain lion Puma concolor) locomotor specialists, as well as semi‐aquatic (polar bear Ursus maritimus) species; all showed a nearly two‐fold increase in peak energy expenditure when avoiding threats. As the duration and frequency of threats to wild species continue to grow, cumulative energetic costs are becoming more apparent. In view of this, attention to the energy demands of apex predators will provide vital predictive power to anticipate mismatches between a species' functional design and human‐induced pressures, and allow for the development of conservation strategies based on how species are built to survive. A free Plain Language Summary can be found within the Supporting Information of this article.

Effect of Aerobic Exercise Training and Deconditioning on Oxidative Capacity and Muscle Mitochondrial Enzyme Machinery in Young and Elderly Individuals.

Mitochondrial dysfunction is thought to be involved in age-related loss of muscle mass and function (sarcopenia). Since the degree of physical activity is vital for skeletal muscle mitochondrial function and content, the aim of this study was to investigate the effect of 6 weeks of aerobic exercise training and 8 weeks of deconditioning on functional parameters of aerobic capacity and markers of muscle mitochondrial function in elderly compared to young individuals. In 11 healthy, elderly (80 ± 4 years old) and 10 healthy, young (24 ± 3 years old) volunteers, aerobic training improved maximal oxygen consumption rate by 13%, maximal workload by 34%, endurance capacity by 2.4-fold and exercise economy by 12% in the elderly to the same extent as in young individuals. This evidence was accompanied by a similar training-induced increase in muscle citrate synthase (CS) (31%) and mitochondrial complex I–IV activities (51–163%) in elderly and young individuals. After 8 weeks of deconditioning, endurance capacity (−20%), and enzyme activity of CS (−18%) and complex I (−40%), III (−25%), and IV (−26%) decreased in the elderly to a larger extent than in young individuals. In conclusion, we found that elderly have a physiological normal ability to improve aerobic capacity and mitochondrial function with aerobic training compared to young individuals, but had a faster decline in endurance performance and muscle mitochondrial enzyme activity after deconditioning, suggesting an age-related issue in maintaining oxidative metabolism.

Elevated ROS depress mitochondrial oxygen utilization efficiency in cardiomyocytes during acute hypoxia.

Mitochondria are important sites for the production of ATP and the generation of ROS in cells. However, whether acute hypoxia increases ROS generation in cells or affects ATP production remains unclear, and therefore, monitoring the changes in ATP and ROS in living cells in real time is important. In this study, cardiomyocytes were transfected with RoGFP for ROS detection and MitGO-Ateam2 for ATP detection, whereby ROS and ATP production in cardiomyocytes were respectively monitored in real time. Furthermore, the oxygen consumption rate (OCR) of cardiomyocytes was measured. Similar results were produced for adult and neonatal rat cardiomyocytes. Hypoxia (1% O2) reduced the basal OCR, ATP-linked OCR, and maximal OCR in cardiomyocytes compared with these OCR levels in the cardiomyocytes in the normoxic group (21% O2). However, ATP-linked OCR, normalized to maximal OCR, was increased during hypoxia, indicating that the electron leakage of complex III exacerbated the increase of ATP-linked oxygen consumption during hypoxia and vice versa. Combined with the result that cardiomyocytes expressing MitGO-Ateam2 showed a significant decrease in ATP production during hypoxia compared with that of normoxic group, acute hypoxia might depress the mitochondrial oxygen utilization efficiency of the cardiomyocytes. Moreover, cardiomyocytes expressing Cyto-RoGFP or IMS-RoGFP showed an increase in ROS generation in the cytosol and the mitochondrial intermembrane space (IMS) during hypoxia. All of these results indicate that acute hypoxia generated more ROS in complex III and increased mitochondrial oxygen consumption, leading to less ATP production. In conclusion, acute hypoxia depresses the mitochondrial oxygen utilization efficiency by decreasing ATP production and increasing oxygen consumption as a result of the enhanced ROS generation at mitochondrial complex III.

Design method of a modified layered aerobic waste landfill divided by coarse material.

To overcome the weaknesses of traditional landfills, a modified aerobic landfill concept with intermediate covers of coarse material between waste layers functioning as facilities of drainage and aeration has been proposed recently. In this study, a one-dimensional coupled model, including aerobic biodegradation, oxygen diffusion, and advection, is proposed to describe oxygen distribution in this new type of landfill. Homotopy analysis method and perturbation method are applied to solve this model at passive aeration and active aeration, respectively. The model has six input variables, that is, oxygen diffusion coefficient, gas permeability, maximum oxygen consumption rate, layer thickness of waste, and injection pressure and extraction pressure. A combination of their typical values gives rise to over 700,000 scenarios which can be calculated by the proposed solution. The coupled effect of the above variables on oxygen migration is quantitatively investigated, followed by an estimation formula of the minimum oxygen concentration in waste layer. The maximum waste layer thickness is defined as a function of other variables for a given aeration target of oxygen volume concentration larger than 5%. A generalized design method of waste layer thickness, injection pressure, and extraction pressure is then developed for the newly proposed modified layered aerobic landfill, which can promote its popularization and application.

Abstract P019: Renal Mitochondrial Bioenergetics In Salt-sensitive Hypertension Is Affected By ANP

There are clinical data suggesting that low levels of Atrial Natriuretic Peptide (ANP) aggravate susceptibility to salt-sensitive (SS) hypertension. ANP is known to affect mitochondria in many tissues, however, little is known about the effects of ANP on renal mitochondrial function. According to our earlier studies, Dahl SS rats lacking ANP exhibit increased blood pressure and pronounced kidney injury. We hypothesized that in SS hypertension ANP deficiency affects renal mitochondrial bioenergetics and contributes to renal function impairment. SS hypertension was induced in male SS NPPA-/- ( Nppa knockout in Dahl SS background, KO) and SS WT (wild type, WT) rats by a high salt (HS) 4% NaCl diet administered for 21 days. Age-matched control animals were fed a normal (NS) 0.4% NaCl salt diet. A combination of in vivo studies, molecular biology and tests of mitochondria isolated from renal cortex (seahorse respiration and spectrofluorimetry assays using TMRM, Amplex Red and MCLA) were used to probe the role ANP in mitochondrial function. Data was analyzed with ANOVA followed by Holm-Sidak post hoc. We report a significant decrease in mitochondrial membrane potential in the SS NPPA-/- rats vs SS WT (25 ± 4% decrease in KO vs WT on NS, and a 16 ± 5% decrease in KO on HS). Furthermore, mitochondrial H 2 O 2 (57.7 ± 7.4 (WT) vs 57.6 ± 1.3 au (KO), p&lt;0.0001) and superoxide (36.6± 1.8 au (WT) vs 67.9 ± 5.2 au (KO), p&lt;0.0001) levels were increased in the KO on a HS diet. Next, we antioxidant capacity was elevated in the SS NPPA-/- rats on HS diet in comparison with SS WT , and increased SOD2 levels were observed in the KO animals. Furthermore, SS NPPA-/- rats exhibit higher MCU (mitochondrial calcium uniporter) activity than SS WT , implying an ANP-dependent effect on mitochondrial calcium influx. Seahorse assay revealed dramatic elevation of the basal, ATP-linked, maximal and spare oxygen consumption rate (OCR) in the cortical mitochondria of the knockout rats on HS, while in HS fed SS WT rats these OCR parameters were, as expected, reduced (vs NS). Therefore, deficiency of circulating ANP leads to significant changes of renal mitochondrial bioenergetics, potentially via effects on mitochondrial calcium uptake, which in turn affects respiratory chain activity leading to oxidative stress.

Studies on the effects of bone marrow stem cells on mitochondrial function and the alleviation of ARDS.

Mesenchymal stem cells (MSCs) can alleviate acute respiratory distress syndrome (ARDS), but the mechanisms involved are unclear, especially about their specific effects on cellular mitochondrial respiratory function. Thirty mice were allocated into the Control, LPS, and LPS + Bone marrow mesenchymal stem cell (BMSC) group (n = 10/group). Mouse alveolar epithelial cells (MLE-12) and macrophage cells (RAW264.7) were divided into the same groups. Pathological variation, inflammation-related factors, reactive oxygen species (ROS), ATP levels, and oxygen consumption rate (OCR) were analyzed. Pathologic features of ARDS were observed in the LPS group and were significantly alleviated by BMSCs. The trend in inflammation-related factors among the three groups was the LPS group > LPS + BMSC group > Control group. In the MLE-12 co-culture system, IL-6 was increased in the LPS group but not significantly reduced in the LPS + BMSC group. In the RAW264.7 co-culture system, IL-1β, TNF-α, and IL-10 levels were all increased in the LPS group, IL-1β and TNF-α levels were reduced by BMSCs, while IL-10 level kept increasing. ROS and ATP levels were increased and decreased respectively in both MLE-12 and RAW264.7 cells in the LPS groups but reversed by BMSCs. Basal OCR, ATP-linked OCR, and maximal OCR were lower in the LPS groups. Impaired basal OCR and ATP-linked OCR in MLE-12 cells were partially restored by BMSCs, while impaired basal OCR and maximal OCR in RAW264.7 cells were restored by BMSCs. BMSCs improved the mitochondrial respiration dysfunction of macrophages and alveolar epithelial cells induced by LPS, alleviated lung tissue injury, and inflammatory response in a mouse model of ARDS.

Indices of leg resistance artery function are independently related to cycling V̇O2 max.

PurposeWhile maximum blood flow influences one's maximum rate of oxygen consumption (V̇O2max), with so many indices of vascular function, it is still unclear if vascular function is related to V̇O2max in healthy, young adults. The purpose of this study was to determine if several common vascular tests of conduit artery and resistance artery function provide similar information about vascular function and the relationship between vascular function and V̇O2max.MethodsTwenty‐two healthy adults completed multiple assessments of leg vascular function, including flow‐mediated dilation (FMD), reactive hyperemia (RH), passive leg movement (PLM), and rapid onset vasodilation (ROV). V̇O2max was assessed with a graded exercise test on a cycle ergometer.ResultsIndices associated with resistance artery function (e.g., peak flow during RH, PLM, and ROV) were generally related to each other (r = 0.47–77, p < .05), while indices derived from FMD were unrelated to other tests (p < .05). Absolute V̇O2max (r = 0.57–0.73, p < .05) and mass‐specific V̇O2max (r = 0.41–0.46, p < .05) were related to indices of resistance artery function, even when controlling for factors like body mass and sex. FMD was only related to mass‐specific V̇O2max after statistically controlling for baseline artery diameter (r = 0.44, p < .05).ConclusionIndices of leg resistance artery function (e.g., peak flow during RH, PLM, and ROV) relate well to each other and account for ~30% of the variance in V̇O2max not accounted for by other factors, like body mass and sex. Vascular interventions should focus on improving indices of resistance artery function, not conduit artery function, when seeking to improve exercise capacity.

Berberine attenuates the abnormal ectopic lipid deposition in skeletal muscle

BackgroundLipid deposition in non-adipose tissue is associated with a propensity to obesity. Skeletal muscle mitochondrial dysfunction, evidenced by incomplete beta oxidation may contribute to ectopic lipid deposition during high fat diet-induced obesity. Berberine (BBR) has been proved to possess the properties of improving metabolic disorders in patients with obesity or type 2 diabetes mellitus. However, the precise mechanism remains obscure. MethodsMice were treated with berberine and metabolic profile were analyzed. Mitochondrial number and function were detected after berberine treatment in vitro and in vivo. The role of Adenosine 5‘-monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) was verified after RNA interference or adenovirus infection. ResultsIn the current study, we investigated the influence of berberine on the lipid deposition of skeletal muscle and found that berberine could increase the mitochondrial number and function both in vivo and in vitro. Furthermore, berberine promoted the expression of PGC-1α, the crucial transcriptional coactivator related to mitochondrial biogenesis and function, through AMPK pathway. Berberine reduced the basal oxygen consumption rates (OCR) but increased the maximal OCR in C2C12 myocytes, which indicated that berberine could increase the potential function of mitochondria. ConclusionOur results proved that berberine can protect the lean body mass from excessive lipid accumulation, by promoting the mitochondrial biogenesis and improving fatty acid oxidation in an AMPK/PGC-1α dependent manner.

Functional training program: the impact on depression, anxiety and sleep quality in adolescents

Depression, anxiety and lack of sleep are one of the most common causes of illness among adolescents. Possible reasons for this increase include use of social networks and exposure to artificial light from electronic devices. Little is known whether functional training can be an alternative intervention to improve these parameters in adolescents. The aim of the study was to investigate the effect of 6-week exercise intervention on the level of maximum oxygen consumption, depression, anxiety and sleep quality among boy and girl school adolescents. Thirty-four participants were analyzed, 23 boys and 11 girls, between 15 and 17 years old. The adolescents underwent 2 weekly sessions of moderate functional training for a total of 6 weeks. Depression, anxiety levels and sleep quality were measured before and after exercise intervention. Girls exhibited higher levels of anxiety and depression than boys at baseline. Poor sleep quality was observed mostly in the adolescent boys (60.9%), when compared to the adolescent girls (36.3%). Strikingly, depression levels were positively correlated with sleep quality in both sexes. A negative correlation was found between VO2 max, anxiety and sleep quality only in the girls. Six weeks of functional training increased VO2 max levels and sleep quality only in the boys (p < 0.02). These results suggest that 6 weeks of exercise intervention twice a week was enough to improve maximum rate of oxygen consumption and daytime sleep dysfunction in school adolescents.

Heme Synthesis Inhibition Blocks Angiogenesis via Mitochondrial Dysfunction.

SummaryThe relationship between heme metabolism and angiogenesis is poorly understood. The final synthesis of heme occurs in mitochondria, where ferrochelatase (FECH) inserts Fe2+ into protoporphyrin IX to produce proto-heme IX. We previously showed that FECH inhibition is antiangiogenic in human retinal microvascular endothelial cells (HRECs) and in animal models of ocular neovascularization. In the present study, we sought to understand the mechanism of how FECH and thus heme is involved in endothelial cell function. Mitochondria in endothelial cells had several defects in function after heme inhibition. FECH loss changed the shape and mass of mitochondria and led to significant oxidative stress. Oxidative phosphorylation and mitochondrial Complex IV were decreased in HRECs and in murine retina ex vivo after heme depletion. Supplementation with heme partially rescued phenotypes of FECH blockade. These findings provide an unexpected link between mitochondrial heme metabolism and angiogenesis.

Cardiometabolic risk factors are associated with immune cell mitochondrial respiration in humans.

Modifiable cardiometabolic risk factors induce the release of proinflammatory cytokines and reactive oxygen species from circulating peripheral blood mononuclear cells (PBMCs), resulting in increased cardiovascular disease risk and compromised immune health. These changes may be driven by metabolic reprogramming of PBMCs, resulting in reduced mitochondrial respiration; however, this has not been fully tested. We aimed to determine the independent associations between cardiometabolic risk factors including BMI, blood pressure, fasting glucose, and plasma lipids with mitochondrial respiration in PBMCs isolated from generally healthy individuals (n = 21) across the adult lifespan (12 men/9 women; age, 56 ± 21 yr; age range, 22-78 yr; body mass index, 27.9 ± 5.7 kg/m2; blood pressure, 123 ± 16/72 ± 10 mmHg; glucose, 90 ± 14 mg/dL; low-density lipoprotein cholesterol (LDL-C), 111 ± 22 mg/dL; and high-density lipoprotein cholesterol (HDL-C), 62 ± 16 mg/dL). PBMCs were isolated from whole blood by density-dependent centrifugation and used to assess mitochondrial function by respirometry. Primary outcomes included basal and maximal oxygen consumption rate (OCR), which were subsequently used to determine spare respiratory capacity and OCR metabolic potential. After we corrected for systolic blood pressure (SBP), diastolic blood pressure (DBP), and blood glucose, LDL-C was negatively associated with maximal respiration (r = -0.56, P = 0.016), spare respiratory capacity (r = -0.58, P = 0.012), and OCR metabolic potential (r = -0.71, P = 0.0011). In addition, SBP was negatively associated with OCR metabolic potential (r = -0.62, P = 0.0056) after we corrected for DBP, blood glucose, and LDL-C. These data suggest a link between blood cholesterol, SBP, and mitochondrial health that may provide insight into how cardiometabolic risk factors contribute to impaired immune cell function.NEW & NOTEWORTHY Independent of other cardiometabolic risk factors, low-density lipoprotein cholesterol, and systolic blood pressure were found to be negatively associated with several parameters of mitochondrial respiration in peripheral blood mononuclear cells of healthy adults. These data suggest that low-density lipoprotein cholesterol and systolic blood pressure may induce metabolic reprogramming of immune cells, contributing to increased cardiovascular disease risk and impaired immune health.

Valproic acid promotes mitochondrial dysfunction in primary human hepatocytes in vitro; impact of C/EBP\u03b1-controlled gene expression

Valproic acid (VPA) is a frequently prescribed anti-epileptic drug which is known to cause liver toxicity and steatosis through mitochondrial dysfunction. Nevertheless the mechanisms underlying these adverse effects are incompletely understood. In this study, we determined the effect of relatively short (3 h) or prolonged (72 h) exposure to VPA on mitochondrial function in primary human hepatocytes (PHHs). While 3 h VPA exposure did not affect oxygen consumption rates (OCRs) in PHHs, prolonged exposure (24–72 h) significantly reduced basal and maximal OCRs. Given that in particular prolonged VPA exposure is required to cause mitochondrial dysfunction, we investigated gene expression data after VPA exposure for 24, 48, 72 h and 72 h VPA followed by a 72 h washout period. We were able to reduce the comprehensive gene expression changes into a more comprehensible set of 18 TFs that were predicted to be persistently activated after 72 h of VPA exposure. Lentiviral knock-down of one of the candidate TFs, C/EBPα, partly rescued VPA-induced mitochondrial dysfunction. Furthermore, RNA-Seq analysis of shC/EBPα and shGFP control PHHs identified 24 genuine C/EBPα target genes that are regulated in response to prolonged VPA exposure in PHHs. Altogether this provides new insights on the involvement of C/EBPα in driving VPA-induced mitochondrial dysfunction in human liver cells. This hub gene, with its downstream regulators involved in this deregulation, thus represent potential new biomarkers for VPA-induced mitochondrial dysfunction.