Search Results (93)

Background: Excess accumulation of white adipose tissue is linked to the development of obesity and type 2 diabetes, both of which are associated with systemic metabolic dysfunction. One promising approach is to convert white adipocytes into beige adipocytes, which have greater thermogenic potential and improved insulin sensitivity. Trans-resveratrol (RES), a polyphenolic compound known to have multiple metabolic benefits, has been reported to promote browning of adipocytes and improve insulin signaling; however, it is unclear whether sex and diabetic status modify RES’s effects. Methods: We evaluated the ability of RES to induce browning and increase insulin sensitivity in adipose-derived stromal cells (ADSCs) derived from diabetic db/db mice and explored the extent to which these responses are modulated by sex and diabetic status. Subcutaneous ADSCs were isolated from wildtype (WT) and diabetic (db/db) male and female mice and then treated with RES during beige adipocyte differentiation. Results: RES enhanced the expression of Pgc1α and Ucp1 mRNA and increased mitochondrial proton leak in ADSCs of both WT and db/db mice. RES also enhanced insulin-induced AKT phosphorylation in all groups of ADSCs. Notably, the effects of RES on browning and insulin signaling were influenced by the sex and diabetic status of the mice, as ADSCs from female diabetic mice responded differently compared with those from their WT or male counterparts. Conclusions: These findings highlight the importance of considering sex and diabetic status when developing browning strategies to target obesity and type 2 diabetes. Full article

Alcohol misuse is twice as prevalent among people living with HIV (PWH), and this increases the risk of pulmonary complications even in those receiving antiretroviral therapy. Our prior work showed that the alcohol metabolite, acetaldehyde, activates nuclear factor kappa B p65 (p65), leading to HIV replication and interleukin (IL)-1β activation in alveolar macrophages (AMs). Since the aforementioned processes are energy-demanding, which conversely impair mitochondrial functions, we hypothesized that acetaldehyde-induced p65 drives AMs to a mitochondrial hyperactive state to promote HIV replication and IL-1β release and induces oxidative stress and mitochondrial dysfunction. Since we found pioglitazone (PIO) to be a negative regulator of p65, we postulate that PIO suppresses HIV replication and IL-1β activation in AMs by restricting p65-induced mitochondrial hyperactivation. Murine AMs were exposed to acetaldehyde via the acetaldehyde generating system (AGS) and infected in vitro with EcoHIV, a chimeric ecotropic HIV construct. AGS + EcoHIV activated p65, resulting in enhanced ATP-linked mitochondrial respiration, proton leak, non-mitochondrial respiration and the generation of reactive oxygen species (ROS) in AMs. Inhibition of mitochondrial ATP synthesis with low-dose oligomycin attenuated AGS-induced HIV replication and AGS + EcoHIV-induced IL-1β release from AMs. PIO treatment, which attenuated AGS-induced p65 activation, suppressed proton leak, non-mitochondrial oxygen consumption, ROS, and IL-1β and p24 release. While p65-induced mitochondrial hyperactivation represents AMs’ adaptive response to the energy demands imposed by HIV replication and proinflammatory activation when exposed to acetaldehyde, PIO treatment may offer a novel therapeutic strategy to restore adequate mitochondrial bioenergetics in the AMs of PWH who misuse alcohol. Full article

Aging is a major risk factor for cardiovascular disease, driving progressive structural and functional decline of the myocardium. Mitochondria, the primary source of ATP through oxidative phosphorylation, are essential for cardiac contractility, calcium homeostasis, and redox balance. In the aging heart, mitochondria show morphological alterations including cristae disorganization, swelling, and fragmentation, along with reduced OXPHOS efficiency. These defects increase proton leak, lower ATP production, and elevate reactive oxygen species (ROS), causing oxidative damage. Concurrent disruptions in mitochondrial fusion and fission further impair turnover and quality control, exacerbating mitochondrial dysfunction and cardiac decline. Serum response factor (SRF) signaling, a crucial regulator of cytoskeletal and metabolic gene expression, plays a key role in modulating mitochondrial function during cardiac aging. Dysregulation of SRF impairs mitochondrial adaptability, contributing to dysfunction. Additionally, reduced levels of nicotinamide adenine dinucleotide (NAD⁺) hinder sirtuin-dependent deacetylation, further compromising mitochondrial efficiency and stress resilience. These cumulative defects activate regulated cell death pathways, leading to cardiomyocyte loss, fibrosis, and impaired diastolic function. Mitochondrial dysfunction therefore serves as both a driver and amplifier of cardiac aging, accelerating the transition toward heart failure. This narrative review aims to provide a comprehensive overview of mitochondrial remodeling in the aging myocardium, examining the mechanistic links between mitochondrial dysfunction and myocardial injury. We also discuss emerging therapeutic strategies targeting mitochondrial bioenergetics and quality control as promising approaches to preserve cardiac function and extend cardiovascular health span in the aging population. Full article

Pentavalent sodium antimoniate (Sb(V)) has been used for over 50 years in leishmaniasis treatment. Sb(V) is converted into trivalent antimony (Sb(III)) within macrophages acting as a prodrug by disrupting fatty acid beta-oxidation and glycolysis, impairing the energy metabolism of the parasite. Despite extensive use, the effects of antimonials on host mitochondria are not well understood. This study investigated the impact of Sb(V) and Sb(III) on mitochondria isolated from mouse hearts via differential centrifugation and lastly incubated with Sb(V) or Sb(III). Mitochondrial function was evaluated by oxygen consumption, ATP production, reactive oxygen species (ROS) generation, and transmembrane potential. Both Sb(V) and Sb(III) reduced oxygen consumption in complex I respiratory states 1, 2, and 3 at 1 µg/mL and 1 ng/mL. ROS production increased in Sb(V)-treated mitochondria. ATP production was impaired by both drugs starting at 1 ng/mL. Proton leak also increased, and significant changes in transmembrane potential were observed at both concentrations. These findings indicate that Sb(V) and Sb(III) directly compromise mitochondrial function from isolated mouse heart mitochondria by reduced ATP production and increased ROS. Full article

Male fertility has declined over the years, partly due to metabolic disorders such as obesity and Type 2 diabetes. Antidiabetic drugs, including GLP-1 receptor agonists like liraglutide, are widely used to manage these conditions and aid in weight loss. Within the male reproductive tract, Leydig cells (LCs) are essential since they produce testosterone. Notably, the influence of antidiabetics on LCs remains a subject of limited investigation. Herein, we aimed to evaluate the effect of liraglutide on the physiology of LCs. To this end, we cultured LCs (BLTK1 cell line) without (control) or in the presence of selected concentrations of liraglutide. We then assessed their metabolic viability, cell proliferation, LDH release, ROS production, mitochondrial membrane potential, and in vivo mitochondrial cell performance, as well as the number of mtDNA copies. We also measured androstenedione production. Our results showed that liraglutide at pharmacological and supra-pharmacological concentrations increased the metabolic viability of LCs and reduced ROS production at all concentrations. Furthermore, the pharmacological concentration of liraglutide increased the basal respiration, maximal respiration, proton leak, and oxygen consumption rate related to ATP-linked production. Androstenedione production remained unchanged, which may be related to the inherent limitations of the cell line in supporting steroidogenesis. Overall, our findings suggest that liraglutide exhibits a potential protective effect on LC function, particularly by enhancing metabolic viability, reducing oxidative stress, and improving mitochondrial performance, highlighting its potential beyond the established role in diabetes and weight management. Full article

Many factors related to obesity can impact how mitochondria produce ATP, such as the uncoupling of oxidative phosphorylation (OXPHOS) caused by proton leaks from built-up free fatty acids (FFA), the increased levels of uncoupling proteins (UCPs), and changes in the levels of ATPase inhibitory protein factors 1 (IF1). Therefore, the present study aimed to assess the rate of ATP synthesis in mitochondria isolated from skeletal and cardiac muscle from animal models of sucrose diet-induced obesity at different time periods. Short periods of sucrose intake (6 and 12 weeks) are sufficient to induce fat accumulation, hypertriglyceridemia, and high plasma FFA. However, a significant decline in the ATP synthesis rate starts to be obvious in mitochondria from skeletal muscle after 24 weeks of sucrose consumption. This impairment of ATP synthesis is associated with increased FFA in skeletal muscle homogenate. ATP synthesis rates in both skeletal and cardiac muscle were found to be sensitive to oleic acid and GDP, a physiological inhibitor of UCPs that has been shown to increase with aging. In addition, a sucrose diet increases the IF1 content in both skeletal and heart muscle, probably to avoid the hydrolytic activity of ATP synthase. In mitochondria from heart muscle, a decrease in the ATP synthesis rate was only observed according to the age in both groups of rats, and it was not affected by sucrose feeding. Our results suggest that the decline of the ATP synthesis rate in mitochondria from skeletal muscle can be due to the accumulation of FFA in skeletal muscle tissue as uncouplers, and the IF1 overexpression induced by the sucrose diet is a response mechanism to avoid the ATP hydrolysis and to save the energy charge reduced by FFA-uncoupling OXPHOS. Full article

Metabolic dysregulation in the heart plays a critical role in the pathogenesis of atrial fibrillation (AF), yet the underlying molecular mechanisms remain unclear. Loss-of-function variants in the zinc finger homeobox 3 gene (ZFHX3) increase AF risk by promoting structural and electrical remodeling. However, the role of ZFHX3 knockdown (KD) in cardiac metabolism has not been fully elucidated. This study investigated the impact of ZFHX3 KD on energy metabolism in atrial myocytes and assessed the therapeutic potential of trimetazidine (TMZ). Seahorse XFe24 extracellular flux analysis, bioluminescent assays, microplate enzyme activity assays, and Western blotting were used to study energy substrate (glucose and fatty acid) oxidation stress, intracellular lactate content, glucose uptake, pyruvate dehydrogenase (PDH) activity, and regulatory protein expression in control and ZFHX3 KD HL-1 cells with or without TMZ (10 μM) treatment. ZFHX3 KD cells exhibited a higher acute response in oxygen consumption after Etomoxir injection, upregulated CD36 and phosphorylated ACC expression, increased glucose uptake and lactate production, reduced PDH activity, and higher levels of PDK4 and LDHA. Furthermore, ZFHX3 KD cells showed mitochondrial Ca²⁺ overload and increased phosphorylated PDH and oxidized CaMKII proteins, all of which were significantly attenuated by TMZ. Additionally, TMZ improved mitochondrial dysfunction in ZFHX3 KD cells by decreasing basal and maximal respiration, spare capacity, and proton leak. These findings suggest that ZFHX3 downregulation shifts substrate preference toward fatty acid utilization at the expense of glucose oxidation, contributing to metabolic and mitochondrial calcium dysregulation. TMZ mitigates these effects, highlighting its therapeutic potential in AF associated with ZFHX3 deficiency. Full article

Rheumatoid arthritis (RA) is an autoimmune disease affecting the synovium. Mitochondrial dysfunction is considered a critical factor in the pathogenesis of RA. The aim of the study was to determine the effect of methotrexate and tofacitinib on mitochondrial function and oxidative stress in an in vitro study on the model synovial cell line SW982. TNF-alpha-stimulated SW982 cells, as well as control untreated cells, were incubated with methotrexate and tofacitinib. A metabolic test was performed to assess mitochondrial function. The oxidative stress generated after the application of the therapeutics was determined by a chromatographic analysis. The results obtained showed an increase in ATP levels (p < 0.0001) and a decrease in proton leak (p < 0.0003) after treatment with tofacitinib. The opposite trend was observed—reduced ATP production (p < 0.0096) and increased levels of proton leak (p < 0.0001)—after treatment with methotrexate. A two-fold increase in 8-ISOPGF2A was measured in comparison to TNF-alpha-stimulated and untreated cells. The dynamics of mitochondrial activity and oxidative stress were monitored in a certified RA model cell line after the administration of two different therapeutics. Methotrexate was found to induce mitochondrial dysfunction and oxidative stress in vitro, while tofacitinib partially improved mitochondrial parameters. Full article

Adenosine signaling plays protective roles in gingival mitochondrial health and inflammation control, with the ectoenzyme CD73 implicated in periodontitis. Here, we investigated the effects of selective adenosine A2a receptor (A2aR) stimulation using the agonist CGS21680 in a mouse model of ligature-induced periodontitis (LIP) and in gingival fibroblast mitochondrial function. Mature C57Bl/6 mice underwent LIP and received daily intraperitoneal injections of CGS21680 (0.1 mg/Kg) or saline. After 8 days, gingival tissues and maxillae were analyzed for alveolar bone loss and Il-1β levels. In parallel, murine gingival fibroblasts (mGFs) were treated with Tnf-α (5 ng/mL) ± CGS21680 (10 µM) to assess mitochondrial function, morphology, and quality control. A2aR activation significantly reduced alveolar bone loss and Il-1β expression in vivo. In vitro, CGS21680 suppressed Tnf-α-induced Cxcl10 and Cxcl12 expressions and enhanced Vegf production. Mitochondrial analysis revealed increased mitochondrial complex levels, membrane potential, and mass, alongside reduced reactive oxygen species (ROS), proton leak, and mitochondrial stress. Ultrastructural studies showed elongated, healthier mitochondria and increased pro-fusion markers, indicating enhanced mitochondrial quality control. Overall, A2aR stimulation attenuates periodontal inflammation and confers mitoprotective effects on gingival fibroblasts, supporting its potential as a therapeutic strategy to both mitigate periodontitis progression and preserve tissue bioenergetics supporting cellular resilience. Full article

Mitochondrial metabolism in the trabecular meshwork (TM) plays a critical role in maintaining intraocular pressure homeostasis by supporting the energy-demanding processes involved in aqueous humour outflow. In primary open-angle glaucoma, oxidative stress impairs mitochondrial function, leading to TM dysfunction. Therefore, understanding and targeting mitochondrial health in TM cells could offer a novel therapeutic strategy. Pyrroloquinoline quinone (PQQ) is a redox cofactor with antioxidant and mitochondrial-enhancing properties. However, its effects on human TM (HTM) cells remain largely unexplored. This study examined PQQ cytoprotective effects against H₂O₂-induced oxidative stress in HTM cells. Seahorse analyses revealed that PQQ alone improves mitochondrial respiration and ATP production. Moreover, PQQ mitigates H₂O₂-induced cellular damage and preserves mitochondrial function by normalising proton leak and increasing ATP levels. Furthermore, TEM and confocal microscopy showed that PQQ can partially alleviate structural damage, restoring mitochondrial network morphology, thereby leading to reduced cell death. Although these protective effects seem not to be mediated by changes in mitochondrial content or activation of the SIRT1/PGC1-α pathway, they may involve modulation of SIRT3, a key factor of mitochondrial metabolism and homeostasis. Overall, these results suggest that PQQ may represent a promising candidate for restoring mitochondrial function and reversing oxidative damage in HTM cells. Full article

Triclosan (TCS) is an antimicrobial agent in a wide range of health care products. It has been found in various human bodily fluids and is a potential reproductive toxicant. However, the effect of TCS on early embryo development in mammalian species is limited. We therefore asked whether exposure to TCS affects mammalian cumulus–oocyte complexes (COCs), and if so, whether the effects persist into the early embryo. COCs, isolated from abattoir-derived bovine ovaries, were exposed to two environmentally relevant doses of TCS (1 and 10 nM) during in vitro maturation. When exposed to 1 nM TCS during in vitro maturation, progesterone release from bovine oocytes was elevated. Furthermore, altered pyruvate metabolism and mitochondrial dysfunction were also observed; specifically, O₂ consumption coupled to ATP production was significantly decreased in COCs after acute exposure to TCS prior to maturation, whereas proton leak from the respiratory chain was increased. Subsequently, TCS-exposed COCs were fertilised. Fewer oocytes were able to develop to blastocyst when exposed to 1 nM TCS during maturation compared to the Control group, and those that did reach the blastocyst displayed impaired glycolytic and amino acid metabolic activity. These findings indicate for the first time that oocytes exposed to TCS during the final stages of maturation give rise to embryos with impaired mitochondrial function, altered steroidogenesis, and disrupted metabolic activity. Full article

Background: Whether intestinal epithelial cells can regulate distant adipose tissue remains a mystery. Methods: Cold-stimulated intestinal epithelial cell-derived exosomes (Cold IEC-Exo) play a pivotal role in enhancing adipose thermogenesis and metabolic homeostasis, as demonstrated in this study. Results: IEC-Exo can accumulate in adipose tissue. Compared with IEC-Exo derived from room temperature mice (RT IEC-Exo), Cold IEC-Exo significantly enhanced the thermogenesis of adipose. In vitro, Cold IEC-Exo directly stimulated thermogenesis in primary adipocytes by elevating oxygen consumption rate, proton leak, and fatty acid uptake, with no effect on glucose uptake. Small RNA sequencing identified miR-674-3p as a key mediator enriched in Cold IEC-Exo. miR-674-3p mimicry replicated Cold IEC-Exo effects, augmenting Ucp1 expression, mitochondrial uncoupling, and fatty acid utilization in adipocytes. Local overexpression of miR-674-3p in BAT and sWAT via AAV in vivo enhanced thermogenesis and attenuated diet-induced glucose intolerance. Conclusions: These findings establish that Cold IEC-Exo, via miR-674-3p transfer, drive adipose thermogenic activation and mitigate metabolic dysfunction, highlighting their therapeutic potential in obesity-related disorders. Full article

Cardiovascular complications are a hallmark of Post-Acute Sequelae of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection (PASC), yet the mechanisms driving persistent cardiac dysfunction remain poorly understood. Emerging evidence implicates mitochondrial dysfunction in immune cells as a key contributor. This study investigated whether CD14⁺⁺ monocytes from long COVID patients exhibit bioenergetic impairment, mitochondrial DNA (mtDNA) damage, and defective oxidative stress adaptation, which may underlie cardiovascular symptoms in PASC. CD14⁺⁺ monocytes were isolated from 14 long COVID patients with cardiovascular symptoms (e.g., dyspnea, angina) and 10 age-matched controls with similar cardiovascular risk profiles. Mitochondrial function was assessed using a Seahorse Agilent Analyzer under basal conditions and after oxidative stress induction with buthionine sulfoximine (BSO). Mitochondrial membrane potential was measured via Tetramethylrhodamine Ethyl Ester (TMRE) assay, mtDNA integrity via qPCR, and reactive oxygen species (ROS) dynamics via Fluorescence-Activated Cell Sorting (FACS). Parallel experiments exposed healthy monocytes to SARS-CoV-2 spike protein to evaluate direct viral effects. CD14⁺⁺ monocytes from long COVID patients with cardiovascular symptoms (n = 14) exhibited profound mitochondrial dysfunction compared to age-matched controls (n = 10). Under oxidative stress induced by buthionine sulfoximine (BSO), long COVID monocytes failed to upregulate basal respiration (9.5 vs. 30.4 pmol/min in controls, p = 0.0043), showed a 65% reduction in maximal respiration (p = 0.4035, ns) and demonstrated a 70% loss of spare respiratory capacity (p = 0.4143, ns) with significantly impaired adaptation to BSO challenge (long COVID + BSO: 9.9 vs. control + BSO: 54 pmol/min, p = 0.0091). Proton leak, a protective mechanism against ROS overproduction, was blunted in long COVID monocytes (3-fold vs. 13-fold elevation in controls, p = 0.0294). Paradoxically, long COVID monocytes showed reduced ROS accumulation after BSO treatment (6% decrease vs. 1.2-fold increase in controls, p = 0.0015) and elevated mitochondrial membrane potential (157 vs. 113.7 TMRE fluorescence, p = 0.0179), which remained stable under oxidative stress. mtDNA analysis revealed severe depletion (80% reduction, p < 0.001) and region-specific damage, with 75% and 70% reductions in amplification efficiency for regions C and D (p < 0.05), respectively. In contrast, exposure of healthy monocytes to SARS-CoV-2 spike protein did not recapitulate these defects, with preserved basal respiration, ATP production, and spare respiratory capacity, though coupling efficiency under oxidative stress was reduced (p < 0.05). These findings suggest that mitochondrial dysfunction in long COVID syndrome arises from maladaptive host responses rather than direct viral toxicity, characterized by bioenergetic failure, impaired stress adaptation, and mitochondrial genomic instability. This study identifies persistent mitochondrial dysfunction in long COVID monocytes as a critical driver of cardiovascular complications in PASC. Key defects—bioenergetic failure, impaired stress adaptation and mtDNA damage—correlate with clinical symptoms like heart failure and exercise intolerance. The stable elevation of mitochondrial membrane potential and resistance to ROS induction suggest maladaptive remodeling of mitochondrial physiology. These findings position mitochondrial resilience as a therapeutic target, with potential strategies including antioxidants, mtDNA repair agents or metabolic modulators. The dissociation between spike protein exposure and mitochondrial dysfunction highlights the need to explore host-directed mechanisms in PASC pathophysiology. This work advances our understanding of long COVID cardiovascular sequelae and provides a foundation for biomarker development and targeted interventions to mitigate long-term morbidity. Full article

Hydrogen leakage in Proton Exchange Membrane (PEM) fuel cells poses critical safety, efficiency, and operational reliability risks. This study introduces an innovative infrared (IR) thermography-based methodology for detecting and quantifying hydrogen leaks towards the outside of PEM fuel cells. The proposed method leverages the catalytic properties of a membrane electrode assembly (MEA) as an active thermal tracer, facilitating real-time visualisation and assessment of hydrogen leaks. Experimental tests were conducted on a single-cell PEM fuel cell equipped with intact and defective gaskets to evaluate the method’s effectiveness. Results indicate that the active tracer generates distinct thermal signatures proportional to the leakage rate, overcoming the limitations of hydrogen’s low IR emissivity. Comparative analysis with passive tracers and baseline configurations highlights the active tracer-based approach’s superior positional accuracy and sensitivity. Additionally, the method aligns detected thermal anomalies with defect locations, validated through pressure distribution maps. This novel, non-invasive technique offers precise, reliable, and scalable solutions for hydrogen leak detection, making it suitable for dynamic operational environments and industrial applications. The findings significantly advance hydrogen’s safety diagnostics, supporting the broader adoption of hydrogen-based energy systems. Full article

Background/Objectives: Early postmortem mitochondrial function and apoptotic activation affect meat quality development. Nicotinamide riboside (NR) supplementation to pigs prior to harvest can improve pork color stability, but its mechanism remains unclear. This study aimed to evaluate the impact of NR supplementation on early postmortem mitochondrial functionality and apoptosis. Methods: Sixteen pigs (N = 16) were individually fed a control or NR-supplemented diet (30 mg·kg body weight⁻¹·d⁻¹) for 10 days prior to harvest. Longissimus dorsi muscle samples were collected at 45 min and 24 h postmortem and analyzed for mitochondrial functionality using high-resolution respirometry and apoptotic protein abundance (apoptosis regulator Bcl-2-associated X (BAX), apoptotic inducing factor (AIF), and caspase 3 (CASP3)) via immunoblotting. Results: NR-supplemented muscle exhibited lower proton leak-associated respiration at 45 min postmortem (p < 0.05), followed by a slower accumulation of mitochondrial outer membrane permeabilization (MOMP; p < 0.05) and a slower loss of mitochondrial integral function (p < 0.05) from 45 min to 24 h postmortem. NR supplementation decreased BAX abundance at 45 min postmortem but increased mature AIF abundance (62 kDa) at 24 h postmortem (p < 0.05). The abundance of CASP3 fragments (~29 kDa) decreased from 45 min to 24 h postmortem, independent of treatment (p < 0.05). Conclusions: NR supplementation demonstrated the potential to protect mitochondrial integral function and alleviate apoptotic activation in early postmortem porcine skeletal muscle, which might contribute to a higher meat color stability in NR-supplemented pork during retail display. Full article