Mitochondrial Capacity Research Articles

Effects of concentric and eccentric exercise regimens on bioenergetic efficiency of lymphocytes in sedentary males

AbstractEccentric exercise training (EET) increases physical performance while having lower metabolic demand than concentric exercise training (CET). Whether EET influences bioenergetic efficiency in peripheral blood mononuclear cells (PBMCs) remains unclear. This study investigates the effects of EET and CET on PBMC phenotypes and mitochondrial functions in blood. Thirty three sedentary healthy males were randomly assigned to either EET (n = 11) or CET (n = 11) that performed at progressively increased from 60% to 80% of maximal absolute workload for 30 min/day, 5 days/week for 6 weeks, or a control group (n = 11) that did not receive any exercise intervention. A graded exercise stress test (GXT) was performed before and after the intervention. PBMC phenotypes and mitochondrial respiratory capacity were analyzed using flowcytometry and high‐resolution respirometry, respectively. In the same absolute workload, EET elicited lower heart rate and rating of perceived exertion than CET. However, EET as CET increased the VO2 level at the ventilatory threshold. Notably, both EET and CET increased central memory (CD45RO+/CD62+/CD3+) T cells and decreased effector memory T cells reexpressing CD45RA (CD45RA+/CD62‐/CD3+). Moreover, the two exercise regimens diminished the loss of mitochondrial membrane potential (ΔΨm) caused by GXT, increased maximal/reserve O2 consumption rates (OCR), and bioenergetic health index in intact PBMCs and enhanced complex I‐/II‐related OCR in PBMCs with a substrate‐rich environment. EET improves aerobic fitness with a lower cardiovascular response to exercise than CET. Moreover, EET as CET reduces senescent T‐cell distribution in blood and improves PBMC bioenergetic efficiency by stabilizing ΔΨm and increasing capacity of oxidative phosphorylation.

Adalimumab Treatment Effects on Inflammation and Adipose Tissue Mitochondrial Respiration in Hidradenitis Suppurativa.

Tumour necrosis factor (TNF)-α is a proinflammatory marker and has been shown to affect mitochondrial function in different tissues. We investigated the effect on adipose tissue (AT) inflammation and mitochondrial respiration in patients with hidradenitis suppurativa (HS) after 12 weeks of treatment with adalimumab, a TNF-α inhibitor. We sampled blood and an AT biopsy from 13 patients with HS and 10 control subjects after an overnight fast. The patients were retested after at least 12 weeks of treatment with adalimumab (40 mg/week). We measured macrophage content and mitochondrial respiration in the AT and interleukin (IL)-1β, IL-6, IL-10, high-sensitivity C-reactive protein (hsCRP), interferon-γ, TNF-α, adiponectin and leptin in plasma. Clinical scores and Dermatology Quality of Life Index (DLQI) were assessed. We found a higher anti-inflammatory macrophage content (CD206+) in the patient group compared with the control group, but no differences between before and after the intervention. No difference in mitochondrial respiration was observed. We observed higher plasma IL-6 and hsCRP concentrations in patients with HS compared to controls, with no differences before and after the intervention. The difference between controls and HS patients was abolished after the intervention. HS patients improved their DLQI after the intervention with no change in clinical scores. Treatment with adalimumab in patients with HS does not alter AT inflammation or mitochondrial respiratory capacity; however, we did see a higher content of anti-inflammatory macrophages in the patient group compared with the control group.

Regulatory roles of histamine receptor in astrocytic glutamate clearance under conditions of increased glucose variability

In diabetic patients, repeated episodes of hypoglycemia can increase glucose variability (GV), which may lead to glutamate neurotoxicity in the brain and consequently affect cognitive functions. Astrocytes play a crucial role in regulating the balance of glutamate within the brain, and their function is influenced by the histamine receptor (HR) signaling pathway. However, the specific role of this mechanism under conditions of high GV is not yet clear. The results showed that increased GV resulted in decreased expression of HRs in mice hippocampus and astrocytes cultured in vitro. Additionally, a decrease in the expression of proteins related to glutamate metabolic clearance was observed, accompanied by a reduction in glutamate reuptake capacity. Notably, the intervention with histidine/histamine was able to reverse the above changes. Further mechanistic studies showed that inhibition of HRs that increased GV led to significant disturbances in astrocytic mitochondrial function. These abnormalities encompassed increased fragmentation morphology and the accumulation of reactive oxygen species, accompanied by decreased mitochondrial respiratory capacity and dysregulation of dynamics. Distinct HR subtypes exhibited variations in the modulation of mitochondrial function, with H3R demonstrating the most pronounced impact. The overexpression of H3R could enhance glutamate metabolic by reversing disturbances in mitochondrial dynamics. Therefore, this study suggests that H3R is able to maintain glutamate metabolic clearance capacity and exert neuroprotective effects in astrocytes that increased GV by regulating mitochondrial dynamic balance. This provides an important basis for potential therapeutic targets for diabetes-related cognitive dysfunction.

Myocardial inflammation is associated with impaired mitochondrial oxidative capacity in ischaemic cardiomyopathy.

Myocardial inflammation and impaired mitochondrial oxidative capacity are hallmarks of heart failure (HF) pathophysiology. The extent of myocardial inflammation in patients suffering from ischaemic cardiomyopathy (ICM) or dilated cardiomyopathy (DCM) and its association with mitochondrial energy metabolism are unknown. We aimed at establishing a relevant role of cardiac inflammation in the impairment of mitochondrial energy production in advanced ischaemic and non-ischaemic HF. We included 81 patients with stage D HF (ICM, n=44; DCM, n=37) undergoing left ventricular assist device implantation (n=59) or heart transplantation (n=22) and obtained left ventricular tissue samples during open heart surgery. We quantified mitochondrial oxidative capacity, citrate synthase activity (CSA) and fibrosis and lymphocytic infiltration. We considered infiltration of >14 CD3+ cells/mm2 relevant inflammation. Patients with ICM or DCM did not differ regarding age (61.5±5.7 vs. 56.5±12.7years, P=0.164), sex (86% vs. 84% male, P=0.725), type 2 diabetes mellitus (34% vs. 18%, P=0.126) or chronic kidney disease (8% vs. 11%, P=0.994). ICM exhibited oxidative capacity reduced by 23% compared to DCM (108.6±41.4 vs. 141.9±59.9pmol/(s*mg), P=0.006). Maximum production of reactive oxygen species was not significantly different between ICM and DCM (0.59±0.28 vs. 0.69±0.36pmol/(s*ml), P=0.196). Mitochondrial content, detected by CSA, was lower in ICM (359.6±164.1 vs. 503.0±198.5nmol/min/mg protein, P=0.002). Notably, relevant inflammation was more common in ICM (27% vs. 6%, P=0.024), and the absolute number of infiltrating leucocytes correlated with lower oxidative capacity (r=-0.296, P=0.019). Fibrosis was more prevalent in ICM (20.9±21.2 vs. 7.2±5.6% of area, P=0.002), but not associated with oxidative capacity (r=-0.13, P=0.327). More than every fourth ICM patient with advanced HF displays myocardial inflammation in the range of inflammatory cardiomyopathy associated with reduced mitochondrial oxidative capacity. Future studies may evaluate inflammation in ICM at earlier stages in standardised fashion to explore the therapeutic potential of immunosuppression to influence trajectories of HF in ICM.

Fucoidan from Undaria pinnatifida Enhances Exercise Performance and Increases the Abundance of Beneficial Gut Bacteria in Mice

Fucoidans, known for their diverse biological properties such as anti-inflammatory, antiviral, antitumor, and immune stimulatory effects, have recently gained attention for their potential benefits in exercise endurance, muscle mass, and anti-fatigue. However, the mechanisms by which fucoidans enhance exercise performance are still unclear. To investigate these effects, we administered 400 mg/kg/day of fucoidan extract derived from Undaria pinnatifida to 64 C57BL/6J mice over 10 weeks. We evaluated changes in running activity, mitochondrial-related gene expression in skeletal muscle, and alterations in the intestinal microbiome. Our results showed that fucoidan supplementation significantly increased daily running distance and muscle mass by 25.5% and 10.4%, respectively, in mice on a standard chow diet, and with more modest effects observed in those on a high-fat diet (HFD). Additionally, fucoidan supplementation led to a significant increase in beneficial gut bacteria, including Bacteroides/Prevotella, Akkermansia muciniphila, and Lactobacillus, along with a notable reduction in the Firmicutes/Bacteroidetes ratio, indicating improved gut microbiome health. Mechanistically, fucoidan supplementation upregulated the mRNA expression of key genes related to mitochondrial biogenesis and oxidative capacity, such as COX4, MYH1, PGC-1α, PPAR-γ, and IGF1, in both standard chow and HFD-fed mice. Our findings suggest that fucoidan supplementation enhances exercise performance, improves muscle function, and positively modulates the gut microbiome in mice, regardless of diet. These effects may be attributed to fucoidans’ potential prebiotic role, promoting the abundance of beneficial gut bacteria and contributing to enhanced exercise performance, increased muscle strength, and improved recovery.

Higher myocardial mitochondrial ketone body oxidation capacity in human heart failure

Abstract Introduction/Purpose Recent studies suggest that the ketone bodies (KB) beta-hydroxybutyrate (HBA) and acetoacetate (ACA) are relevant substrates for myocardial energy metabolism in heart failure (HF). However, the amount of KB-dependent mitochondrial respiration in HF has not yet been quantified. High-resolution respirometry (HRR) is the gold-standard method for quantifying substrate-dependent mitochondrial oxidative capacity. Therefore, we aimed to evaluate the association between myocardial KB-dependent oxidative capacity and human HF using HRR. Methods The primary endpoint of this single-center prospective cohort study was KB-dependent and overall mitochondrial oxidative capacity in permeabilized myocardium. We used two different protocols for our measurements. In the first HRR protocol, conventional respirometry substrates including fatty acids, complex I- and complex II substrates were used to quantify the maximum coupled oxidative phosphorylation capacity (OXPHOS). Leak respiration was quantified using oligomycin to calculate the respiratory control ratio (RCR, state 3/state 4o), and leak control ratio (LCR, state 4o/state u). In the second protocol which was recently established by our working group, HBA and ACA were used as respirometry substrates to quantify KB-dependent respiration down to the enzyme level. The relative contribution of the KBs was obtained by comparing HBA- and ACA-derived respiration to OXPHOS. We applied both protocols to myocardial samples from individuals with advanced HF (HF group, catheter-acquired endomyocardial biopsies from non-ischemic HF patients or samples of explanted hearts collected during orthotopic heart transplantation surgery in end-stage heart failure patients) as well as previously heart transplanted individuals without current heart failure (Control group). Results Controls and HF had similar demographic characteristics, with comparable age distribution (mean±SD, 56.3±10.3 vs. 54.2±10.7 years, p=0.36), sex (68.75% vs. 66.67% male, p=0.87), or body mass index (25.0±5.8 vs. 29.0±10.6 kg/m2, p=0.08) and differed significantly in cardiac index (3.06±0.67 vs. 1.93±0.44) and ejection fraction (55.8±10.2 vs. 26.6±9.1) (both p<0.0001). The HF group exhibited lower OXPHOS and respiration for all substrate combinations tested (Fig. 1A). In contrast, KB-dependent respiration did not differ between HF and controls (Fig. 1B). The relative HBA-dependent respiration (Fig. 1C) and the relative and absolute ACA-dependent respiration (Fig. 1C and D) were higher in the HF group compared to controls. Mitochondrial uncoupling (LCR) (0.47±0.29 vs. 0.44±0.09 [AU], p=0.79) and coupling efficiency (RCR) (2.75±1.38 vs. 2.11±0.39 [AU], p=0.15) were not different between the groups. Conclusion These findings suggest that mitochondria in the failing heart can utilize KBs for OXPHOS to a greater extent and further hint towards KB metabolism as a potential therapeutic target for HF.

Differential production of mitochondrial reactive oxygen species between mouse (Mus musculus) and crucian carp (Carassius carassius).

In most vertebrates, oxygen deprivation and subsequent re-oxygenation are associated with mitochondrial impairment and excess production of reactive oxygen species (ROS) like hydrogen peroxide (H2O2). This in turn triggers a cascade of cell-damaging events in a temperature-dependent manner. The crucian carp (Carassius carassius) is one of few vertebrates that survives months without oxygen at cold temperatures and overcomes oxidative damage during re-oxygenation periods. Mitochondria of this anoxia-tolerant species therefore serve as an excellent model in translational research to study adaptation and resilience to low oxygen conditions and thermal variability. Here, we used high-resolution respirometry on isolated mitochondria from hearts of crucian carp and the anoxia-intolerant mouse (Mus musculus), at 37 and 8°C; two temperatures relevant for transplantation medicine (i.e., graft preservation and subsequent rewarming). We find: (1) a striking difference in H2O2 release between the two species at 37°C despite comparable mitochondrial efficiency and capacity, (2) a massive H2O2 release after inhibition of complex V in mouse at 37°C that is absent in crucian carp, and prevented in mouse by incubation at 8°C or uncoupling with a protonophore at 37°C, and (3) indications that differences in mitochondrial complex I and II capacity and thermal sensitivity influence the release of mitochondrial H2O2 relative to respiration. Our findings provide comparative insights into a spectrum of mitochondrial adaptations in vertebrates and the importance of thermal variability. Furthermore, the species- and temperature-related changes associated with mitochondria highlighted in this study may help identify mitochondria-based targets for translational medicine.

Validation of metaxin-2 deficient C. elegans as a model for MandibuloAcral Dysplasia associated to mtx-2 (MADaM) syndrome

MandibuloAcral Dysplasia associated to MTX2 gene (MADaM) is a recently described progeroid syndrome (accelerated aging disease) whose clinical manifestations include skin abnormalities, growth retardation, and cardiovascular diseases. We previously proposed that mtx-2-deficient C. elegans could be used as a model for MADaM and to support this, we present here our comprehensive phenotypic characterization of these worms using atomic force microscopy (AFM), transcriptomic, and oxygen consumption rate analyses. AFM analysis showed that young mtx-2-less worms had a significantly rougher, less elastic cuticle which becomes significantly rougher and less elastic as they age, and abnormal mitochondrial morphology. mtx-2 C. elegans displayed slightly delayed development, decreased pharyngeal pumping, significantly reduced mitochondrial respiratory capacities, and transcriptomic analysis identified perturbations in the aging, TOR, and WNT-signaling pathways. The phenotypic characteristics of mtx-2 worms shown here are analogous to many of the human clinical presentations of MADaM and we believe this validates their use as a model which will allow us to uncover the molecular details of the disease and develop new therapeutics and treatments.

Mitochondrial oxidative phosphorylation capacity in skeletal muscle measured by ultrafast Z-spectroscopy (UFZ) MRI at 3T.

To investigate the feasibility of rapid CEST MRI acquisition for evaluating oxidative phosphorylation (OXPHOS) in human skeletal muscle at 3T, utilizing ultrafast Z-spectroscopy (UFZ) combined with MRI and the Polynomial and Lorentzian line-shape Fitting (PLOF) technique. UFZ MRI on muscle was evaluated with turbo spin echo (TSE) and 3D EPI readouts. Five healthy subjects performed in-magnet plantar flexion exercise (PFE) and subsequent changes of amide, PCr, and partial PCr mixed Cr (Cr+) CEST dynamic signals post-exercise were enabled by PLOF fitting. PCr/Cr CEST signal was further refined through pH correction by using the ratios between PCr/Cr and amide signals, named PCAR/CAR, respectively. UFZ MRI with TSE readout significantly reduces acquisition time, achieving a temporal resolution of <50 s for collecting high-resolution Z-spectra. Following PFE, the recovery/decay times (τ) for both PCr and Cr in the gastrocnemius muscle of the calf were notably longer when determined using PCr/Cr CEST compared to those after pH correction with amideCEST, namely = 87.1 ± 15.8 s and = 98.1 ± 20.4 s versus = 32.9 ± 19.7 s and = 43.0 ± 13.0 s, respectively. obtained via 31P MRS ( = 50.3 ± 6.2 s) closely resemble those obtained from pH-corrected PCr/Cr CEST signals. The outcomes suggest potential of UFZ MRI as a robust tool for non-invasive assessment of mitochondrial function in skeletal muscles. pH correction is critical for the reliable OXPHOS measurement by CEST.

Ultraviolet radiation inhibits mitochondrial bioenergetics activity.

Mitochondria play an important role in cellular function, not only as a major site of adenosine triphosphate (ATP) production but also by regulating energy expenditure, apoptosis signaling, control of the cell cycle, cellular growth, cell differentiation, transportation of metabolites, and production of reactive oxygen species. Interaction with electromagnetic waves can lead to dysregulation or alterations in the patterns of energy activities in the mitochondria. Ultraviolet light (UV) can be found in sunlight and artificial sources, such as lamps. UV radiation can cause damage to DNA, proteins, and lipids. Besides that, UV radiation is largely used in microorganism disinfection. To establish possible alterations in mitochondrial bioenergetics, this study proposes to investigate the UV (at two distinct intervals) effects on isolated mitochondria from mice liver to obtain direct responses and selective permeability of the internal membrane information. UVA-371 and UVC-255 nm lamps were used to irradiate, at different doses varying from 22.5 to 756 mJ/cm2, isolated mitochondria samples. Mitochondrial respiration pathways were investigated by high-resolution respirometry, and possible mitochondrial membrane damages were evaluated by mitochondrial swelling by spectrophotometer analysis. UVC irradiation results (in the higher dose) indicate decrease in 75% of mitochondrial bioenergetics capacity, such as limitation of oxidative phosphorylation in 60% and increased energy dissipation in 30%. Mitochondrial swelling experiments (spectrophotometer) indicated inner membrane damage, and consequently a loss of selective permeability. Direct correlation between irradiation and effect responses was observed, mitochondrial bioenergetics is severely affected by UVC radiation, but (UVA) radiation did not present bioenergetic alterations. These alterations can contribute to improving the knowledge behind the cell death mechanism in disinfection UV light and UV therapy such as phototherapy.

Metformin restores autophagic flux and mitochondrial function in late passage myoblast to impede age-related muscle loss

Sarcopenia, which refers to age-related muscle loss, presents a significant challenge for the aging population. Age-related changes that contribute to sarcopenia include cellular senescence, decreased muscle stem cell number and regenerative capacity, impaired autophagy, and mitochondrial dysfunction. Metformin, an anti-diabetic agent, activates AMP-activated protein kinase (AMPK) and affects various cellular processes in addition to reducing hepatic gluconeogenesis, lowering blood glucose levels, and improving insulin resistance. However, its effect on skeletal muscle cells remains unclear. This study aimed to investigate the effects of metformin on age-related muscle loss using a late passage C2C12 cell model. The results demonstrated that metformin alleviated hallmarks of cellular senescence, including SA-β-gal activity and p21 overexpression. Moreover, treatment with pharmacological concentrations of metformin restored the reduced differentiation capacity in late passage cells, evident through increased myotube formation ability and enhanced expression of myogenic differentiation markers such as MyoD, MyoG, and MHC. These effects of metformin were attributed to enhanced autophagic activity, normalization of mitochondrial membrane potential, and improved mitochondrial respiratory capacity. These results suggest that pharmacological concentrations of metformin alleviate the hallmarks of cellular senescence, restore differentiation capacity, and improve autophagic flux and mitochondrial function. These findings support the potential use of metformin for the treatment of sarcopenia.

Loss of atrial natriuretic peptide signaling causes insulin resistance, mitochondrial dysfunction, and low endurance capacity.

Type 2 diabetes (T2D) and obesity are strongly associated with low natriuretic peptide (NP) plasma levels and a down-regulation of NP guanylyl cyclase receptor-A (GCA) in skeletal muscle and adipose tissue. However, no study has so far provided evidence for a causal link between atrial NP (ANP)/GCA deficiency and T2D pathogenesis. Here, we show that both systemic and skeletal muscle ANP/GCA deficiencies in mice promote metabolic disturbances and prediabetes. Skeletal muscle insulin resistance is further associated with altered mitochondrial function and impaired endurance running capacity. ANP/GCA-deficient mice exhibit increased proton leak and reduced content of mitochondrial oxidative phosphorylation proteins. We further show that GCA is related to several metabolic traits in T2D and positively correlates with markers of oxidative capacity in human skeletal muscle. Together, these results indicate that ANP/GCA signaling controls muscle mitochondrial integrity and oxidative capacity in vivo and plays a causal role in the development of prediabetes.

Lipid peroxidation products induce carbonyl stress, mitochondrial dysfunction, and cellular senescence in human and murine cells.

Lipid enals are electrophilic products of lipid peroxidation that induce genotoxic and proteotoxic stress by covalent modification of DNA and proteins, respectively. As lipid enals accumulate to substantial amounts in visceral adipose during obesity and aging, we hypothesized that biogenic lipid enals may represent an endogenously generated, and therefore physiologically relevant, senescence inducers. To that end, we identified that 4-hydroxynonenal (4-HNE), 4-hydroxyhexenal (4-HHE) or 4-oxo-2-nonenal (4-ONE) initiate the cellular senescence program of IMR90 fibroblasts and murine adipose stem cells. In such cells, lipid enals induced accumulation of γH2AX foci, increased p53 signaling, enhanced expression of p21Cip1, and upregulated the expression and secretion of numerous cytokines, chemokines, and regulatory factors independently from NF-κB activation. Concomitantly, lipid enal treatment resulted in covalent modification of mitochondrial proteins, reduced mitochondrial spare respiratory capacity, altered nucleotide pools, and increased the phosphorylation of AMP kinase. Lipid-induced senescent cells upregulated BCL2L1 (Bcl-xL) and BCL2L2 (Bcl-w). and were resistant to apoptosis while pharmacologic inhibition of BAX/BAK macropores attenuated lipid-induced senescence. Insitu, the 4-HNE scavenger L-carnosine ameliorated the development of the cellular senescence, while in visceral fat of obese C57BL/6J mice, L-carnosine reduced the abundance of 4-HNE-modified proteins and blunted the expression of senescence biomarkers CDKN1A (p21Cip1), PLAUR, BCL2L1, and BCL2L2. Taken together, the results suggest that lipid enals are endogenous regulators of cellular senescence and that biogenic lipid-induced senescence (BLIS) may represent a mechanistic link between oxidative stress and age-dependent pathologies.

TOMM40-APOE chimera linking Alzheimer's highest risk genes: a new pathway for mitochondria regulation and APOE4 pathogenesis.

The patho-mechanism of apolipoprotein variant, APOE4, the strongest genetic risk for late-onset Alzheimer's disease (AD) and longevity, remains unclear. APOE's neighboring gene, TOMM40 (mitochondria protein transport channel), is associated with brain trauma outcome and aging-related cognitive decline, however its role in AD APOE4-independently is controversial. We report that TOMM40 is prone to transcription readthrough into APOE that can generate spliced TOMM40-APOE mRNA chimera (termed T9A2) detected in human neurons and other cells and tissues. T9A2 translation tethers APOE (normal APOE3 or APOE4) to near-full-length TOM40 that is targeted to mitochondria. Importantly, T9A2-APOE3 boosts mitochondrial bioenergetic capacity and decreases oxidative stress significantly more than T9A2-APOE4 and APOE3, and lacking in APOE4. We describe detailed interactomes of these actors that may inform about the activities and roles in pathogenesis. T9A2 uncovers a new candidate pathway for mitochondria regulation and oxidative stress-protection that are impaired in APOE4 genotypes and could initiate neurodegeneration.

Brain Abnormalities in Young Single- and Double-Heterozygote Mice for Both Nkx2-1- and Pax8-Null Mutations.

In humans and mice, Nkx2-1 and Pax8 are crucial morphogenic transcription factors defining the early development of the thyroid and specific extrathyroidal tissues. By using 3-month-old single or double heterozygotes for Nkx2-1- and Pax8-null mutations (DHTP) mice, we studied brain abnormalities under different human-like dysthyroidisms, focusing on putative alterations of specific neurotransmitter systems, expression of markers of pre- and post-synaptic function and, given the physio-pathological role mitochondria have in controlling the bioenergetic status of neurons, of mitochondrial dynamics and oxidative balance. Compared to Wt controls, DHTP mice, bearing both systemic and brain hypothyroidism, showed altered expression of synaptic markers, generic and cholinergic (corroborated by immunohistochemistry in caudate, putamen, hippocampus, and basal forebrain) and glutamatergic ones, and reduced expression of key proteins of synaptic plasticity potency and several isoforms of glutamate receptors. The brain of DHTP mice was characterized by lower levels of H2O2 and imbalanced mitochondrial dynamics. Nkx2-1 + / - mice showed dopaminergic neuron-specific alterations, morphologically, more evident in the substantia nigra of DHTP mice. Nkx2-1 + / - mice also showed enhanced mitochondrial biogenesis and oxidative capacity likely as a global response of the brain to Nkx2-1 haploinsufficiency and/or to their elevated T3 circulating levels. Reduced transcription of both tyrosine hydroxylase and dopamine transporter was observed in Pax8 + / - euthyroid mice, suggesting a dopaminergic dysfunction, albeit likely at an early stage, but consistent with the deregulated glucose homeostasis observed in such animals. Overall, new information was obtained on the impact of haploinsufficiency of Pax8 and NKx2-1 on several brain neuroanatomical, molecular, and neurochemical aspects, thus opening the way for future targeting brain dysfunctions in the management of both overt and subclinical thyroid dysfunctions.

7086 Disrupted Mitochondrial Function in Alström Syndrome- A Monogenic Model of Insulin Resistance and Obesity

Abstract Disclosure: S. Ali: None. S. Heising: None. V. Veeranna: None. A. Vincent: None. G.S. Xavier: None. T. Geberhiwot: None. Alström syndrome (ALMS) is a rare monogenic disease typified by severe insulin resistance (IR) and obesity. IR and obesity are cardinal features of metabolic syndrome. The metabolic effects of insulin at key target tissues leads to metabolic haemostasis by promoting glucose and lipid uptake and metabolism to generate energy in cells. Although insulin is a major regulator of fuel metabolism, its effects on mitochondrial ATP production in severe insulin resistance are unclear. RNASeq data from adipose tissue (AT) from patients with ALMS show downregulation of the expression of genes associated with mitochondrial respiratory chain function, pointing towards possible altered mitochondrial function in ALMS. We therefore undertook a detailed assessment of mitochondrial oxidative phosphorylation capacity (OXPHOS) in skeletal muscle (SM) in ALMS. We performed SM biopsy in 10 ALMS and 10 healthy control volunteers that were age, gender and Body Mass Index matched. The SM was subjected to high resolution respirometry, the gold standard method to quantify mitochondrial function ex vivo, using OROBOROS Oxygraph -2k (O2k) system. Overall OXPHOS was higher in control SM compared to ALMS, with maximal respiration of 62.96±19.2 and 44.24 ± 12.53 pmol/(s*mg), respectively (p&amp;lt;0.05).Reduced oxygen influx was observed in ALMS SM in comparison to controls for fatty acid ß oxidation (6.7±5.96 vs 7.87±2.7 pmol/(s*mg);p&amp;lt;0.05, at complex I (19.4 ± 8.98 vs 29.7 ±5.3 pmol/(s*mg);p&amp;lt;0.05, and at complex II (34.98 ±11.75 vs 53.52± 13.2 pmol/(s*mg) ;p&amp;lt;0.05. Mitochondrial membrane integrity was unaffected during these experiments. Therefore, our analysis unveils a consistent reduction in mitochondrial respiration across all the electron transport pathway. This noteworthy finding suggests impairment in respiratory function and the electron transport chain in mitochondria, a crucial aspect of cellular energy metabolism. Several studies have previously linked IR with mitochondrial dysfunction, where insulin-resistant rodents and humans have shown blunted mitochondrial response to ATP generation. Our results align with this body of evidence emphasizing the significance of investigating the underlying mechanism contributing to this phenomenon. These findings could pave the way to exploring potential mitochondrial-targeted therapies to restore mitochondrial function and therefore, improve insulin sensitivity to tackle IR in ALMS. Presentation: 6/2/2024

DACRA induces profound weight loss, satiety control, and increased mitochondrial respiratory capacity in adipose tissue.

Dual amylin and calcitonin receptor agonists (DACRAs) are therapeutic candidates in the treatment of obesity with beneficial effects on weight loss superior to suppression of food intake. Hence, suggesting effects on energy expenditure by possibly targeting mitochondria in metabolically active tissue. Male rats with HFD-induced obesity received a DACRA, KBP-336, every third day for 8 weeks. Upon study end, mitochondrial respiratory capacity (MRC), - enzyme activity, - transcriptional factors, and -content were measured in perirenal (pAT) and inguinal adipose tissue. A pair-fed group was included to examine food intake-independent effects of KBP-336. A vehicle-corrected weight loss (23.4 ± 2.8%) was achieved with KBP-336, which was not observed to the same extent with the food-restricted weight loss (12.4 ± 2.8%) (P < 0.001). Maximal coupled respiration supported by carbohydrate and lipid-linked substrates was increased after KBP-336 treatment independent of food intake in pAT (P < 0.01). Moreover, oligomycin-induced leak respiration and the activity of citrate synthase and β-hydroxyacetyl-CoA-dehydrogenase were increased with KBP-336 treatment (P < 0.05). These effects occurred without changes in mitochondrial content in pAT. These findings demonstrate favorable effects of KBP-336 on MRC in adipose tissue, indicating an increased energy expenditure and capacity to utilize fatty acids. Thus, providing more mechanistic insight into the DACRA-induced weight loss.

Luteolin alleviates muscle atrophy, mitochondrial dysfunction and abnormal FNDC5 expression in high fat diet-induced obese rats and palmitic acid-treated C2C12 myotubes

Obesity is associated with a series of skeletal muscle impairments and dysfunctions, which are characterized by metabolic disturbances and muscle atrophy. Luteolin is a phenolic phytochemical with broad pharmacological activities. The present study aimed to evaluate the protective effects of Luteolin on muscle function and explore the potential mechanisms in high-fat diet (HFD)-induced obese rats and palmitic acid (PA)-treated C2C12 myotubes. Male Sprague-Dawley (SD) rats were fed with a control diet or HFD and orally administrated 0.5% sodium carboxymethyl cellulose (vehicle) or Luteolin (25, 50 and 100 mg/kg, respectively) for 12 weeks. The results showed that Luteolin ameliorated HFD-induced body weight gain, glucose intolerance and hyperlipidemia. Luteolin also alleviated muscle atrophy, decreased ectopic lipid deposition and prompted muscle-fiber-type conversion in the skeletal muscle. Meanwhile, we observed an evident improvement in mitochondrial quality control and respiratory capacity, accompanied by reduced oxidative stress. Mechanistic studies indicated that AMPK/SIRT1/PGC-1α signaling pathway plays a key role in the protective effects of Luteolin on skeletal muscle in the obese states, which was further verified by using specific inhibitors of AMPK and SIRT1. Moreover, the mRNA expression levels of markers in brown adipocyte formation were significantly up-regulated post Luteolin supplementation in different adipose depots. Taken together, these results revealed that Luteolin supplementation might be a promising strategy to prevent obesity-induced loss of mass and biological dysfunctions of skeletal muscle.

Release kinetics and protective effect of novel curcumin-based nanoliposome modified with pectin, whey protein isolates and hyaluronic acid against oxidative stress

In the present study, a novel nanoliposome loaded with Curcumin (Cur) (NNLs-Cur) was established to overcome the gastrointestinal digestive barrier and enhance mitochondrial targeting capacity, exerting the antioxidant capacity of Cur. Noteworthy, NNLs-Cur was modified by pectin, whey protein isolates and hyaluronic acid. The results showed that the structure of traditional nanoliposomes loaded with Cur (NLs-Cur) was destroyed during digestion. However, NNLs-Cur maintained intact structural morphology, and the release of Cur in the stomach and intestines was consistent with zero-order and first-order kinetic models, respectively. Interestingly, the survival rate of HL-7702 cells after being damaged by H2O2 was 40.53 %, while the survival rate after treated with NNLs-Cur reached 99.87 %. Besides, the fluorescence localization indicated Cur in NNLs-Cur could escape lysosomal and achieve mitochondria targeting. Compared with NLs-Cur, the damaged cells treated with NNLs-Cur increased activities of catalase (CAT), glutathione peroxide (GSH-Px) and superoxide dismutase (SOD) from 16.16 ± 0.52, 16.92 ± 2.28 and 30.10 ± 0.93 U/mgprot to 19.09 ± 0.52, 20.41 ± 1.79 and 33.81 ± 0.29 U/mgprot, respectively. Malondialdehyde (MDA) content and reactive oxygen species (ROS) level of the oxidative damaged cells were reduced, mitochondrial membrane potential was restored, and cell apoptosis was reduced. This study provides theoretical guidance for realizing the industrial application of efficient targeted delivery Cur.

Analysis of fat oxidation capacity during cardiopulmonary exercise testing indicates long-lasting metabolic disturbance in patients with post-covid-19 syndrome

Background & AimsPost-COVID-19 Syndrome (PCS) is characterized by symptoms including fatigue, reduced physical performance, dyspnea, cognitive impairment, and psychological distress. The mechanisms underlying the onset and severity of PCS point to mitochondrial dysfunction as significant contributor. This study examined fat oxidation as a function of mitochondrial capacity during exercise. MethodsSingle-center prospective cohort study during inpatient rehabilitation. Cardiopulmonary exercise testing and assessment of fatigue using questionnaires were performed at admission and discharge. Detailed spirometric breath-by-breath data were used to calculate substrate oxidation rates. ResultsPatients (N=145; 38% women; 49.7±11.4 years) were referred to rehabilitation 253.4±130.6 days after infection. Lead symptoms included fatigue/exercise intolerance (79.9%), shortness of breath (77.0%), and cognitive dysfunction (55.1%). Fat oxidation capacity was disturbed in PCS patients overall (AUC: 11.3[10.7-11.9]) compared to healthy controls (p<0.0001), with hospitalization during acute infection predicting the level of disturbance (p<0.0001). Low exercise capacity and high fatigue scores resulted in reduced fat oxidation (both p<0.0001). In particular, younger males were affected by significantly reduced fat oxidation capacity (sex: p=0.002; age: p<0.001). Metabolic disturbance was significantly improved during exercise-based rehabilitation (AUC: 14.9[14.4-15.4]; p<0.0001), even for the group of younger impaired males (+44.2%; p<0.0001). Carbohydrate oxidation was not impaired. ConclusionsPCS-specific restrictions in fat oxidation may indicate persistent mitochondrial dysfunction. Clinical assessment of PCS patients should include detailed breath-by-breath analysis during exercise to identify metabolic alterations especially in the group of younger males identified in this report. Exercise-based rehabilitation results in improved exercise capacity and fat oxidation and thus likely mitochondrial function. Clinical Trials: NCT06468722