Ana P. Valencia

Experiencing an involuntary weight loss plateau is common after behavioral weight loss. During such periods, sustained negative energy balance activates counterregulatory mechanisms that restore energy balance and may slow further weight loss. However, the cellular bioenergetic changes occurring specifically during a spontaneous weight loss plateau have not been investigated. We studied mitochondrial respiratory capacity in peripheral mononuclear cell populations from participants with obesity, both before and after an intensive lifestyle intervention (ILI). Body weight was tracked continuously over 18 months using a remote electronic scale, enabling retrospective categorization of outcome measures by weight loss phases: active weight loss (aWL), plateau (PL), or regain (RG). Differences in mitochondrial respiration were observed in T cells but not in monocytes across these phases. During aWL, mitochondrial respiratory capacity was similar to pre-ILI; however, basal, ATP-linked, maximal, and spare respiratory capacity were significantly lower during the PL and RG phases. In addition, ATP-linked respiration was lower in the PL and RG, despite higher mitochondrial citrate synthase activity in the PL relative to pre-ILI. These results indicate that T-cell bioenergetics may be responsive to shifts in energy balance during weight reduction. The novel phase-specific classification used in this study uncovers dynamic bioenergetic adaptations that may contribute to a weight loss plateau. Article Highlights: Weight loss is a dynamic process, characterized by transitions between active weight loss, plateau, and regain, yet underlying metabolic features across these phases remain poorly defined. This study tested whether mitochondrial bioenergetics in peripheral mononuclear cells differ in humans across weight loss phases during behavioral weight loss. Mitochondrial respiratory capacity of T cells is significantly reduced during plateau and regain phases, despite an increase in mitochondrial content. Phase-based classification of weight change reveals bioenergetic differences in T cells that are associated with transitions in energy balance within the weight-reduced state.

Improving health outcomes via sustained weight loss and maintenance requires advancing understanding of the metabolic, appetitive, and neurological alterations that counteract—and eventually halt—weight loss. Prior studies have demonstrated increased appetite as well as metabolic adaptations, such as increased energy efficiency, in response to weight loss. However, previous study designs utilized experimentally determined weight loss plateaus and did not investigate spontaneously occurring plateaus nor study participants in their natural, free-living, environments during weight loss. The Assessing Diet, Appetite, and Physiology Throughout weight loss (ADAPT) study was designed to address these limitations of prior research and elucidate mechanistic factors involved in spontaneous cessation of intentional weight loss in humans. ADAPT enrolls participants with obesity who undergo behavioral weight loss via a reduced calorie diet and increased physical activity. Participants’ daily weight is monitored remotely, and new analytic approaches identify weight-loss phases in real time so that study assessments can be targeted to each participants’ individualized trajectory during dynamic weight loss. Deep phenotyping of participants includes anthropometric, metabolic, neurophysiologic, and behavioral assessments; physical activity and physiologic monitoring via wearable devices; and serial sampling of biological tissues such as blood, adipose tissue, and muscle. In summary, the ADAPT study design is generating a uniquely informative and integrative dataset for deepening understanding of the biological mechanisms that halt behaviorally-induced weight loss and thereby limit its long-term health benefits for patients with obesity. NCT06174389.

Key Points: Nicotinamide riboside and coenzyme Q10 supplementation showed distinct beneficial effects on whole-blood transcriptome, inflammatory cytokines, and oxidative stress. Nicotinamide riboside treatment altered the expression of genes associated with metabolism and immune response coinciding with a decrease in markers of oxidative stress. Coenzyme Q10 supplementation altered genes associated with lipid metabolism coinciding with reductions in markers of oxidative stress and inflammatory cytokines. Background: Mitochondria-driven oxidative/redox stress and inflammation play a major role in CKD pathophysiology. Compounds targeting mitochondrial metabolism may improve mitochondrial function, inflammation, and redox stress; however, there is limited evidence of their efficacy in CKD. Methods: We conducted a pilot, randomized, double-blind, placebo-controlled crossover trial comparing the effects of 1200 mg/d of coenzyme Q10 (CoQ10) or 1000 mg/d of nicotinamide riboside (NR) supplementation with placebo in 25 patients with moderate-to-severe CKD (eGFR 2). We assessed changes in blood transcriptome using 3′-Tag-Seq gene expression profiling and changes in prespecified secondary outcomes of inflammatory and oxidative stress biomarkers. For a subsample of participants (n=14), we assessed lymphocyte and monocyte bioenergetics using an extracellular flux analyzer. Results: The (mean±SD) age, eGFR, and body mass index of the participants were 61±11 years, 37±9 ml/min per 1.73 m², and 28±5 kg/m², respectively. Of the participants, 16% had diabetes and 40% were female. Compared with placebo, NR-mediated transcriptomic changes were enriched in gene ontology terms associated with carbohydrate/lipid metabolism and immune signaling, whereas CoQ10 changes were enriched in immune/stress response and lipid metabolism gene ontology terms. NR increased plasma IL-2 (estimated difference, 0.32; 95% confidence interval [CI], 0.14 to 0.49 pg/ml), and CoQ10 decreased both IL-13 (estimated difference, −0.12; 95% CI, −0.24 to −0.01 pg/ml) and C-reactive protein (estimated difference, −0.11; 95% CI, −0.22 to 0.00 mg/dl) compared with placebo. Both NR and CoQ10 reduced five-series F2-isoprostanes (estimated difference, −0.16 and −0.11 pg/ml, respectively; P < 0.05 for both). NR, but not CoQ10, increased the Bioenergetic Health Index (estimated difference, 0.29; 95% CI, 0.06 to 0.53) and spare respiratory capacity (estimated difference, 3.52; 95% CI, 0.04 to 7 pmol/min per 10,000 cells) in monocytes. Conclusions: Six weeks of NR and CoQ10 improved markers of oxidative stress, inflammation, and cell bioenergetics in patients with moderate-to-severe CKD. Clinical Trial registry name and registration number: NCT03579693.

Peripheral mononuclear cells (PBMCs) exhibit robust changes in mitochondrial respiratory capacity in response to health and disease. While these ... Jove

Background: Current studies suggest mitochondrial dysfunction is a major contributor to impaired physical performance and exercise intolerance in chronic kidney disease (CKD). We conducted a clinical trial of coenzyme Q10 (CoQ10) and nicotinamide riboside (NR) to determine their impact on exercise tolerance and metabolic profile in patients with CKD. Methods: We conducted a randomized, placebo-controlled, double-blind, crossover trial comparing CoQ10, NR, and placebo in 25 patients with an estimated glomerular filtration rate (eGFR) of less than 60mL/min/1.73 m ² . Participants received NR (1,000 mg/day), CoQ10 (1,200 mg/day), or placebo for 6 weeks each. The primary outcomes were aerobic capacity measured by peak rate of oxygen consumption (VO ₂ peak) and work efficiency measured using graded cycle ergometry testing. We performed semitargeted plasma metabolomics and lipidomics. Results: Participant mean age was 61.0 ± 11.6 years and mean eGFR was 36.9 ± 9.2 mL/min/1.73 m ² . Compared with placebo, we found no differences in VO ₂ peak ( P = 0.30, 0.17), total work ( P = 0.47, 0.77), and total work efficiency ( P = 0.46, 0.55) after NR or CoQ10 supplementation. NR decreased submaximal VO ₂ at 30 W ( P = 0.03) and VO ₂ at 60 W ( P = 0.07) compared with placebo. No changes in eGFR were observed after NR or CoQ10 treatment ( P = 0.14, 0.88). CoQ10 increased free fatty acids and decreased complex medium- and long-chain triglycerides. NR supplementation significantly altered TCA cycle intermediates and glutamate that were involved in reactions that exclusively use NAD ⁺ and NADP ⁺ as cofactors. NR decreased a broad range of lipid groups including triglycerides and ceramides. Conclusions: Six weeks of treatment with NR or CoQ10 improved markers of systemic mitochondrial metabolism and lipid profiles but did not improve VO ₂ peak or total work efficiency. Trial registration: ClinicalTrials.gov NCT03579693. Funding: National Institutes of Diabetes and Digestive and Kidney Diseases (grants R01 DK101509, R03 DK114502, R01 DK125794, and R01 DK101509).

ID 24886 Poster Board 10 Background: While the mechanism(s) underlying APOE4-induced AD risk remains unclear, apoE4 levels in the brains of humans and transgenic mice (Tg) expressing human APOE4 are lower than those expressing APOE3, and apoE4-lipoproteins are poorly lipidated compared to apoE3-lipoproteins. Increasing the lipidation of apoE4 can stabilize apoE4-lipoproteins, thus making this process an attractive therapeutic target. Several enzymes affect CNS cholesterol levels including ACAT (acyl-CoA:cholesterol-acyltransferase), which catalyzes the formation of intracellular cholesteryl-ester droplets, reducing the intracellular free cholesterol (FC) pool. Inhibition of ACAT increases the FC pool, making the lipids available for secretion to extracellular apoE-containing lipoproteins. Previous studies using commercially available ACAT inhibitors, including Avasimibe (AVAS), as well as ACAT-knock out (KO) mice, demonstrate reduced plaque burden, gliosis, amyloid-beta peptide (Ab), and altered amyloid precursor protein (APP) processing in familial AD (FAD)-Tg mouse models. However, the effects of AVAS in the presence of human apoE4 remain unknown. Our hypothesis is that AVAS, via inhibition of ACAT, will increase the FC pool, promoting ABCA1-mediated efflux of cholesterol to nascent apoE4-lipoproteins. This correction of apoE4 structure via lipidation will restore its function in the CNS, including clearance of oAβ and reducing neuroinflammation. Methods: Male E4FAD-Tg mice (5xFAD^+/-/APOE4^+/+) were treated by oral gavage with AVAS from 6-8 months. Synaptic proteins were measured by Western blot and learning and memory by Morris Water Maze (MWM). Lipid droplets/cell were analyzed by staining with LipidSpot. Ab pathology was evaluated by measuring Ab solubility (3-step sequential extraction followed by ELISA) and Ab/amyloid deposition (immunostaining). Neuroinflammation (astrogliosis and microgliosis) were evaluated by immuhistochemistry. ApoE levels and lipidation were analyzed by apoE-ELISA and native gels. Results: AVAS treatment significantly reduced intracellular lipid droplets, demonstrating indirect target engagement, increased MWM measures of memory and postsynaptic protein levels, indicating surrogate efficacy, and reduced pathological changes in Aβ solubility/deposition, and neuroinflammation, all critical components of APOE4-modulated AD pathology. However, there was no increase in apoE4 levels or lipidation, while amyloidogenic processing of APP was significantly reduced. Conclusion: This study suggests that the AVAS-induced reduction in Aβ via reduced APP processing was sufficient to reduce AD pathology, while apoE4-lipoproteins remained poorly lipidated. This study was partially sponsored by AbbVie, Inc. AbbVie contributed to the study design, research, and interpretation of data, reviewing, and approving the manuscript.

Aging and poor diet are independent risk factors for heart disease, but the impact of high-sucrose (HS) consumption in the aging heart is understudied. Aging leads to impairments in mitochondrial function that result in muscle dysfunction (e.g., cardiac remodeling and sarcopenia). We tested whether HS diet (60%kcal sucrose) would accelerate muscle dysfunction in 24-month-old male CB6F1 mice. By week 1 on HS diet, mice developed significant cardiac hypertrophy compared to age-matched chow-fed controls. The increased weight of the heart persisted throughout the 4-week treatment, while body weight and strength declined more rapidly than controls. We then tested whether HS diet could worsen cardiac dysfunction in old mice and if the mitochondrial-targeted drug, elamipretide (ELAM), could prevent the diet-induced effect. Old and young mice were treated with either ELAM or saline as a control for 2 weeks, and provided with HS diet or chow on the last week. As demonstrated in the previous experiment, old mice had age-related cardiac hypertrophy that worsened after one week on HS and was prevented by ELAM treatment, while the HS diet had no detectable effect on hypertrophy in the young mice. As expected, mitochondrial respiration and reactive oxygen species (ROS) production were altered by age, but were not significantly affected by HS diet or ELAM. Our findings highlight the vulnerability of the aged heart to HS diet that can be prevented by systemic targeting of the mitochondria with ELAM.

Background: Eccentric contractions induce muscle damage (EIMD) that compromises muscle function. Poor recovery from EIMD has been suggested to be a contributor to the decline in muscle function evident in sarcopenia, but it is unclear which aspects of muscle function are more susceptible to disruption by EIMD in old versus young muscle. The purpose of this study was to determine the extent of impairment in contractile function (force, fatigue, tetanus and twitch kinetics) during the recovery from EIMD in VO mice compared to young adult (YA).Methods: Male CB6F1 were obtained from National Institure of Aging colony. VO mice were 29–31 months of age, and YA mice were 7–9 months of age. The plantarflexor muscles were subjected to 20 eccentric contractions in vivo to induce injury (EIMD). Changes in tetanic force and kinetics were assessed before EIMD, immediately after EIMD and 3 days after EIMD (3d‐EIMD). Force–frequency and rates of fatigue were assessed 3d‐EIMD and compared with baseline. Histological analysis was conducted in injured and non‐injured contralateral gastrocnemius muscle.Results: There was a greater loss in isometric tetanic force immediately following EIMD in VO compared with YA (−31.6% ± 10.4 vs. −21.7% ± 6.0, P < 0.05). At 3d‐EIMD, the rate of contraction of tetanus began to recover in VO, but not in YA (20.8% vs. −6.8%, P < 0.05), whereas the extent of recovery of force tended to be greater in VO than YA (39.3% vs. 17.1%, P = 0.08) when compared with tetanic function immediately after injury. Compared with function pre‐injury (baseline), VO and YA had similar deficits in tetanic force (−7.3% ± 5.3 vs. ‐9.2% ± 6.0, respectively) and kinetics at Day 3. Twitch kinetics (rate of relaxation) recovered faster in VO compared with YA. The rate of muscle fatigue was similar to baseline values, with VO continuing to be more fatigue resistant than YA 3d‐EIMD. There were no detectable differences in muscle mass or myofibre cross‐sectional area despite continued deficits in force following EIMD in either age group.Conclusions: Despite clear functional deficits and greater susceptibility to injury, aged sarcopenic muscle exhibited a similar ability to recover contractile function to younger muscle following EIMD. In addition, neither age group showed accelerated muscle fatigue in the recovery phase after EIMD; thus, sarcopenic mouse muscles do not appear to be more susceptible to long‐term functional impairment than young healthy muscles.