bims-kimdis 2022-09-18 papers

bims-kimdis

Biomed News

on Ketones, inflammation and mitochondria in disease

Issue of 2022–09–18
seventeen papers selected by
Matías Javier Monsalves Álvarez, Universidad de O’Higgins

Oral ketone monoester supplementation does not accelerate recovery of muscle force or modulate circulating cytokine concentrations after muscle damaging eccentric exercise in healthy males and females.
Ketogenic diet uncovers differential metabolic plasticity of brain cells.
Sensing local energetics to acutely regulate mitophagy in skeletal muscle.
Rates of protein synthesis are maintained in brain but reduced in skeletal muscle during dietary sulfur amino acid restriction.
Skeletal muscle oxidative stress and inflammation in aging: Focus on antioxidant and anti-inflammatory therapy.
The Effects of Medium-Chain Triglyceride Oil Supplementation on Endurance Performance and Substrate Utilization in Healthy Populations: A Systematic Review.
Unlocking a novel determinant of athletic performance: The role of the gut microbiota, short-chain fatty acids, and "biotics" in exercise.
Lactate-induced lactylation in skeletal muscle is associated with insulin resistance in humans.
Inflammatory signalling in atrial cardiomyocytes: a novel unifying principle in atrial fibrillation pathophysiology.
Overexpression of UCP3 decreases mitochondrial efficiency in mouse skeletal muscle in vivo.
Recurrent metabolic alkalosis following ketone body treatment of adult mitochondrial trifunctional protein deficiency: A case report.
Altered skeletal muscle SERCA calcium transport efficiency following a thermogenic stimulus.
Leptin-depended NLRP3 inflammasome activation in osteoarthritic chondrocytes is mediated by ROS.
The disturbance of protein synthesis/degradation homeostasis is a common trait of age-related neurodegenerative disorders.
Utility of a Handheld Blood Ketone Meter as a Postmortem Indicator of Diabetic Ketoacidosis.
Computational Model of the Effect of Mitochondrial Dysfunction on Excitation-Contraction Coupling in Skeletal Muscle.
β-hydroxybutyrate impairs monocyte function via the ROS-NLR family pyrin domain-containing three inflammasome (NLRP3) pathway in ketotic cows.

Exp Physiol. 2022 Sep 16.

Oral ketone monoester supplementation does not accelerate recovery of muscle force or modulate circulating cytokine concentrations after muscle damaging eccentric exercise in healthy males and females.

Tom S O Jameson, Hashim Islam, Benjamin T Wall, Jonathan P Little, Francis B Stephens.

   NEW FINDINGS: What is the central question of this study? Does acute ketone monoester supplementation enhance the recovery of muscle force and modulate circulating cytokine concentrations after muscle-damaging eccentric exercise? What is the main finding and its importance? We report that ketone monoester supplementation increased plasma β-hydroxybutyrate concentrations but did not attenuate the reduction in muscle force or the increase in plasma inflammatory cytokine concentrations that occurred after eccentric exercise. Notably we report novel data demonstrating a reduction in plasma TRAIL concentrations after eccentric exercise, highlighting TRAIL signaling as a possibly novel regulator of muscle recovery.
ABSTRACT: Introduction Muscle damaging eccentric exercise is associated with inflammation and impaired muscle force. β-hydroxybutyrate (β-OHB) reduces muscle protein breakdown during inflammation but whether oral ketone monoester supplementation accelerates recovery of muscle force after eccentric exercise is unknown. Methods Sixteen healthy males and females consumed thrice daily ketone monoester (27 g per dose; n = 8; 6 females; KES) or isocaloric maltodextrin placebo (n = 8; 4 females; PLA) drinks (randomized, double-blind, parallel group design) for 3 days beginning immediately after 300 unilateral eccentric quadriceps contractions during complete eucaloric dietary control (1.2 ± 0.1 g·kgBM-1 ·d-1 standardized protein). Bilateral muscle force measurements and venous blood sampling were performed before and 3, 6, 24, 48 and 72 h after eccentric exercise. Results Plasma β-OHB concentrations were greater in KES compared with PLA at 3 (0.56 ± 0.13 vs 0.22 ± 0.04 mM, respectively; P = 0.080) and 6 h (0.65 ± 0.41 vs 0.23 ± 0.02 mM, respectively; P = 0.031) post eccentric exercise. Relative to the control leg, isokinetic work (by 20 ± 21% in PLA and 21 ± 19% in KES [P = 0.008]) and isometric torque (by 23 ± 13% in PLA and 20 ± 18% in KES [P < 0.001]) decreased from baseline at 3 h in the eccentrically exercised leg, and remained below baseline at 48 and 72 h, with no significant group differences. Of eight measured plasma cytokines, IL-6 (P = 0.008) and MCP-1 (P = 0.024) concentrations increased after 6 h, whereas TRAIL concentrations decreased after 3 (P = 0.022) and 6 h (P = 0.011) post exercise with no significant group differences. Conclusion Oral ketone monoester supplementation elevates plasma β-OHB concentrations but does not prevent the decline in muscle force or alter plasma inflammatory cytokine profiles induced by eccentric exercise. This article is protected by copyright. All rights reserved.

Keywords:  BOHB; TRAIL; cytokine; inflammation; β-Hydroxybutyrate

DOI:  https://doi.org/10.1113/EP090546
Sci Adv. 2022 Sep 16. 8(37): eabo7639

Ketogenic diet uncovers differential metabolic plasticity of brain cells.

Tim Düking, Lena Spieth, Stefan A Berghoff, Lars Piepkorn, Annika M Schmidke, Miso Mitkovski, Nirmal Kannaiyan, Leon Hosang, Patricia Scholz, Ali H Shaib, Lennart V Schneider, Dörte Hesse, Torben Ruhwedel, Ting Sun, Lisa Linhoff, Andrea Trevisiol, Susanne Köhler, Adrian Marti Pastor, Thomas Misgeld, Michael Sereda, Imam Hassouna, Moritz J Rossner, Francesca Odoardi, Till Ischebeck, Livia de Hoz, Johannes Hirrlinger, Olaf Jahn, Gesine Saher.

To maintain homeostasis, the body, including the brain, reprograms its metabolism in response to altered nutrition or disease. However, the consequences of these challenges for the energy metabolism of the different brain cell types remain unknown. Here, we generated a proteome atlas of the major central nervous system (CNS) cell types from young and adult mice, after feeding the therapeutically relevant low-carbohydrate, high-fat ketogenic diet (KD) and during neuroinflammation. Under steady-state conditions, CNS cell types prefer distinct modes of energy metabolism. Unexpectedly, the comparison with KD revealed distinct cell type-specific strategies to manage the altered availability of energy metabolites. Astrocytes and neurons but not oligodendrocytes demonstrated metabolic plasticity. Moreover, inflammatory demyelinating disease changed the neuronal metabolic signature in a similar direction as KD. Together, these findings highlight the importance of the metabolic cross-talk between CNS cells and between the periphery and the brain to manage altered nutrition and neurological disease.

DOI: https://doi.org/10.1126/sciadv.abo7639
Front Cell Dev Biol. 2022 ;10 987317

Sensing local energetics to acutely regulate mitophagy in skeletal muscle.

Anna S Nichenko, Kalyn S Specht, Siobhan M Craige, Joshua C Drake.

  The energetic requirements of skeletal muscle to sustain movement, as during exercise, is met largely by mitochondria, which form an intricate, interconnected reticulum. Maintenance of a healthy mitochondrial reticulum is essential for skeletal muscle function, suggesting quality control pathways are spatially governed. Mitophagy, the process by which damaged and/or dysfunctional regions of the mitochondrial reticulum are removed and degraded, has emerged as an integral part of the molecular response to exercise. Upregulation of mitophagy in response to acute exercise is directly connected to energetic sensing mechanisms through AMPK. In this review, we discuss the connection of mitophagy to muscle energetics and how AMPK may spatially control mitophagy through multiple potential means.

Keywords:  AMPK; energetic stress; mitochondria; mitophagy; reactive oxygen species

DOI:  https://doi.org/10.3389/fcell.2022.987317
Front Aging. 2022 ;3 975129

Rates of protein synthesis are maintained in brain but reduced in skeletal muscle during dietary sulfur amino acid restriction.

Wenceslao Martinez, Qian Zhang, Melissa A Linden, Nate Schacher, Sanna Darvish, Emily T Mirek, Jordan L Levy, William O Jonsson, Tracy G Anthony, Karyn L Hamilton.

  Dietary interventions such as sulfur amino acid restriction (SAAR) target multiple drivers of aging, and show promise for preventing or delaying the onset of chronic diseases. SAAR promotes metabolic health and longevity in laboratory animals. The effects of SAAR on proteostasis remain relatively unexplored. We previously reported that SAAR promotes mitochondrial proteostatic maintenance, despite suppression of global protein synthesis, in two peripheral tissues, the liver and skeletal muscle. However, the brain, a tissue vulnerable to age-related neurodegenerative diseases due to the loss of proteostasis, has not been thoroughly studied. Therefore, we sought to reveal proteostatic responses in the brains of mice fed SAAR for 35 days. Here, we demonstrate that male C57Bl/6J mice fed two levels of SAAR maintained rates of protein synthesis in all sub-cellular fractions of the pre-frontal cortex. In comparison, rates of skeletal muscle protein synthesis in SAAR fed mice were slower than control-fed mice. To gain mechanistic insight, we examined several key nutrient/energy sensitive signaling proteins: AMP-activated protein kinase (AMPK), eukaryotic initiation factor 2 (eIF2), and ribosomal protein S6 (rpS6). SAAR had minimal to modest effects on the total abundance and phosphorylation of these proteins in both tissues. Our results indicate that the pre-frontal cortex in brain is resistant to perturbations in protein synthesis in mice fed SAAR, unlike skeletal muscle, which had a reduction in global protein synthesis. The results from this study demonstrate that proteostatic control in brain is of higher priority than skeletal muscle during dietary SAAR.

Keywords:  amino acids; dietary intervention; energy sensing; healthspan; methionine restriction; proteostasis

DOI:  https://doi.org/10.3389/fragi.2022.975129
Front Cell Dev Biol. 2022 ;10 964130

Skeletal muscle oxidative stress and inflammation in aging: Focus on antioxidant and anti-inflammatory therapy.

Mingming Chen, Yiyi Wang, Shoulong Deng, Zhengxing Lian, Kun Yu.

  With aging, the progressive loss of skeletal muscle will have negative effect on multiple physiological parameters, such as exercise, respiration, thermoregulation, and metabolic homeostasis. Accumulating evidence reveals that oxidative stress and inflammation are the main pathological characteristics of skeletal muscle during aging. Here, we focus on aging-related sarcopenia, summarize the relationship between aging and sarcopenia, and elaborate on aging-mediated oxidative stress and oxidative damage in skeletal muscle and its critical role in the occurrence and development of sarcopenia. In addition, we discuss the production of excessive reactive oxygen species in aging skeletal muscle, which reduces the ability of skeletal muscle satellite cells to participate in muscle regeneration, and analyze the potential molecular mechanism of ROS-mediated mitochondrial dysfunction in aging skeletal muscle. Furthermore, we have also paid extensive attention to the possibility and potential regulatory pathways of skeletal muscle aging and oxidative stress mediate inflammation. Finally, in response to the abnormal activity of oxidative stress and inflammation during aging, we summarize several potential antioxidant and anti-inflammatory strategies for the treatment of sarcopenia, which may provide beneficial help for improving sarcopenia during aging.

Keywords:  aging; inflammation; oxidative stress; skeletal muscle; treatment strategy

DOI:  https://doi.org/10.3389/fcell.2022.964130
J Obes Metab Syndr. 2022 Sep 13.

The Effects of Medium-Chain Triglyceride Oil Supplementation on Endurance Performance and Substrate Utilization in Healthy Populations: A Systematic Review.

Tomas J Chapman-Lopez, Yunsuk Koh.

   Background: The use of medium-chain triglyceride (MCT) oil has increased due to its potential for therapeutic and ergogenic properties. Although recent evidence has suggested that MCT oil supplementation may lead to an improvement in endurance and substrate utilization, contradicting studies have reported ergogenic benefits of MCT oil toward exercise performance.
Methods: An extensive systematic review was conducted to assess the role of MCT oil as an ergogenic aid in exercise performance. Moreover, this study examined any alterations in substrate utilization and various physiological components while using MCT oil. The databases searched in this review were PubMed, Embase, CINAHL, and the Cochrane Library.
Results: Most studies reported that MCT oil did not improve exercise performance and had no effect on respiratory exchange ratio, glucose concentration, fat/carbohydrate oxidation, and lactate concentration. Although ketones were increased when supplementing with MCTs, most studies demonstrated that the body could not utilize the MCT oil-induced ketones as its primary energy source during an acute bout of endurance exercise. Thirty grams of MCTs seems to be the safe maximal dosage to minimize adverse reactions during or after exercise.
Conclusion: MCT oil showed very little to no ergogenic effects on exercise performance and substrate utilization in healthy populations. Future research is needed to examine the effects of long-term intake of MCT oil alongside various diets, perhaps a ketogenic diet, on exercise performance within different sports/exercises in a variety of populations.

Keywords:  Capric acid; Caprylic acid; Ketogenic diet; Medium-chain fatty acids; Medium-chain triglyceride oil

DOI:  https://doi.org/10.7570/jomes22028
J Sport Health Sci. 2022 Sep 08. pii: S2095-2546(22)00091-6. [Epub ahead of print]

Unlocking a novel determinant of athletic performance: The role of the gut microbiota, short-chain fatty acids, and "biotics" in exercise.

Kate M Sales, Raylene A Reimer.

  The gut microbiota refers to the collection of trillions of intestinal microorganisms that modulate central aspects of health and disease through influential effects on host physiology. Recently, a connection has been made between the gut microbiota and exercise. Initial investigations demonstrated the beneficial effects of exercise on the gut microbiota, with cross-sectional studies revealing positive correlations between exercise-associated states and healthy gut microbiota and exercise interventions showing post-intervention increases in the abundance of beneficial bacterial taxa. More recent investigations have focused on exploring the reverse relationship: the influence of the gut microbiota on exercise performance. Murine investigations have revealed that certain bacterial taxa may enhance endurance exercise performance by augmenting various aspects of lactate metabolism. Further, short-chain fatty acids (SCFA)-which modulate metabolism at various organ sites, including within skeletal muscle-have been shown to enhance endurance exercise capacity in mice. This review highlights what is currently known about the connection between the gut microbiota and exercise, with a particular focus on the ergogenic potential of the gut microbiota and how it may be leveraged to enhance endurance exercise performance.

Keywords:  Exercise performance; Gut microbiota; Short-chain fatty acids

DOI:  https://doi.org/10.1016/j.jshs.2022.09.002
Front Physiol. 2022 ;13 951390

Lactate-induced lactylation in skeletal muscle is associated with insulin resistance in humans.

Dominic Maschari, Gunjan Saxena, Timothy D Law, Erin Walsh, Mason C Campbell, Leslie A Consitt.

  Elevated circulating lactate has been associated with obesity and insulin resistance. The aim of the current study was to determine if lactate-induced lysine lactylation (kla), a post-translational modification, was present in human skeletal muscle and related to insulin resistance. Fifteen lean (Body Mass Index: 22.1 ± 0.5 kg/m2) and fourteen obese (40.6 ± 1.4 kg/m2) adults underwent a muscle biopsy and 2-h oral glucose tolerance test. Skeletal muscle lactylation was increased in obese compared to lean females (19%, p < 0.05) and associated with insulin resistance (r = 0.37, p < 0.05) in the whole group. Skeletal muscle lactylation levels were significantly associated with markers of anaerobic metabolism (plasma lactate and skeletal muscle lactate dehydrogenase [LDH], p < 0.05) and negatively associated with markers of oxidative metabolism (skeletal muscle cytochrome c oxidase subunit 4 and Complex I [pyruvate] OXPHOS capacity, p < 0.05). Treatment of primary human skeletal muscle cells (HSkMC) with sodium lactate for 24 h increased protein lactylation and IRS-1 serine 636 phosphorylation in a similar dose-dependent manner (p < 0.05). Inhibition of glycolysis (with 2-deoxy-d-glucose) or LDH-A (with sodium oxamate or LDH-A siRNA) for 24 h reduced HSkMC lactylation which paralleled reductions in culture media lactate accumulation. This study identified the existence of a lactate-derived post-translational modification in human skeletal muscle and suggests skeletal muscle lactylation could provide additional insight into the regulation of skeletal muscle metabolism, including insulin resistance.

Keywords:  insulin sensitivity; lactate; lactylation; obesity; post-translation modification; skeletal muscle

DOI:  https://doi.org/10.3389/fphys.2022.951390
Nat Rev Cardiol. 2022 Sep 15.

Inflammatory signalling in atrial cardiomyocytes: a novel unifying principle in atrial fibrillation pathophysiology.

Dobromir Dobrev, Jordi Heijman, Roddy Hiram, Na Li, Stanley Nattel.

Inflammation has been implicated in atrial fibrillation (AF), a very common and clinically significant cardiac rhythm disturbance, but its precise role remains poorly understood. Work performed over the past 5 years suggests that atrial cardiomyocytes have inflammatory signalling machinery - in particular, components of the NLRP3 (NACHT-, LRR- and pyrin domain-containing 3) inflammasome - that is activated in animal models and patients with AF. Furthermore, work in animal models suggests that NLRP3 inflammasome activation in atrial cardiomyocytes might be a sufficient and necessary condition for AF occurrence. In this Review, we evaluate the evidence for the role and pathophysiological significance of cardiomyocyte NLRP3 signalling in AF. We first summarize the evidence for a role of inflammation in AF and review the biochemical properties of the NLRP3 inflammasome, as defined primarily in studies of classic inflammation. We then briefly consider the broader evidence for a role of inflammatory signalling in heart disease, particularly conditions that predispose individuals to develop AF. We provide a detailed discussion of the available information about atrial cardiomyocyte NLRP3 inflammasome signalling in AF and related conditions and evaluate the possibility that similar signalling might be important in non-myocyte cardiac cells. We then review the evidence on the role of active resolution of inflammation and its potential importance in suppressing AF-related inflammatory signalling. Finally, we consider the therapeutic potential and broader implications of this new knowledge and highlight crucial questions to be addressed in future research.

DOI: https://doi.org/10.1038/s41569-022-00759-w
FEBS Lett. 2022 Sep 16.

Overexpression of UCP3 decreases mitochondrial efficiency in mouse skeletal muscle in vivo.

Roberto Codella, Tiago C Alves, Douglas E Befroy, Cheol Soo Choi, Livio Luzi, Douglas L Rothman, Richard G Kibbey, Gerald I Shulman.

  Uncoupling protein-3 (UCP3) is a mitochondrial transmembrane protein highly expressed in muscle that has been implicated in regulating the efficiency of mitochondrial oxidative phosphorylation. Increasing UCP3 expression in skeletal muscle enhances proton leak across the inner mitochondrial membrane and increases oxygen consumption in isolated mitochondria, but its precise function in vivo has yet to be fully elucidated. To examine whether muscle-specific overexpression of UCP3 modulates muscle mitochondrial oxidation in vivo, rates of ATP synthesis were assessed by 31 P magnetic resonance spectroscopy (MRS) and rates of mitochondrial oxidative metabolism were measured by assessing the rate of [2-13 C]acetate incorporation into muscle [4-13 C]- , [3-13 C]-glutamate and [4-13 C]-glutamine by high resolution 13 C/1 H MRS. Using this approach we found that overexpression of UCP3 in skeletal muscle was accompanied by increased muscle mitochondrial inefficiency in vivo as reflected by a 42% reduction in the ratio of ATP synthesis to mitochondrial oxidation.

Keywords:  magnetic resonance spectroscopy; mitochondrial efficiency; mitochondrial uncoupling; muscle energy metabolism

DOI:  https://doi.org/10.1002/1873-3468.14494
JIMD Rep. 2022 Sep;63(5): 407-413

Recurrent metabolic alkalosis following ketone body treatment of adult mitochondrial trifunctional protein deficiency: A case report.

Nina N Stolwijk, Mirjam Langeveld, Bart A W Jacobs, Liffert Vogt, Jorien A Haverkamp, Sacha Ferdinandusse, Carla E M Hollak.

Recent studies have reported the potential for the therapeutic use of ketones in the form of ketone salts (KSs) in pediatric patients with fatty acid oxidation disorders (FAODs). We report a case of ketone salt administration in an adult patient with mitochondrial trifunctional protein deficiency (MTPD), an ultra-rare inborn error of the fatty acid metabolism. This patient was treated with oral KSs during an episode of sepsis of unknown origin. Before KS supplementation was initiated, he had developed severe rhabdomyolysis as well as a respiratory insufficiency that did not respond to emergency treatment aimed at stabilizing the metabolic decompensation by promoting anabolism. Therefore, KS supplementation was attempted twice to support his energy production and help regain metabolic stability. In both instances, KS supplementation led to a considerable metabolic alkalosis, which prompted its discontinuation. This adverse event could have been caused by an increase in extracellular sodium load due to KS administration. Therefore, the clinical applicability of KSs in adults may be limited. Alternative chemical forms of beta-hydroxybutyrate (βHB), such as ketone esters, might provide a more acceptable safety profile for future research into the therapeutic benefits of ketone body supplementation in adult patients with FAODs.

DOI: https://doi.org/10.1002/jmd2.12309
Am J Physiol Regul Integr Comp Physiol. 2022 Sep 12.

Altered skeletal muscle SERCA calcium transport efficiency following a thermogenic stimulus.

Lydia A Heemstra, Lauren G Koch, Steven L Britton, Colleen M Novak.

  Exposure to predator threat induces a rapid and robust increase in skeletal muscle thermogenesis in rats. The central nervous system relays threat information to skeletal muscle through activation of the sympathetic nervous system, but muscle mechanisms mediating this thermogenesis remain unidentified. Given the relevance of sarcolipin-mediated futile calcium cycling through the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump to mammalian muscle non-shivering thermogenesis, we hypothesized that this plays a role in contextually induced muscle thermogenesis as well. This was assessed by measuring enzymatic activity of SERCA and sarcoplasmic reticulum Ca2+ transport, where the apparent coupling ratio-Ca2+ uptake rate divided by ATPase activity rate at a standard Ca2+ concentration-was predicted to decrease in association with muscle thermogenesis. Sprague Dawley rats exposed to predator (ferret) odor (PO) showed a rapid decrease in the apparent coupling ratio in the soleus muscle, indicating SERCA uncoupling compared to control-odor-exposed rats. A rat model of high aerobic fitness and elevated muscle thermogenesis also demonstrated soleus muscle SERCA uncoupling relative to their obesity-prone, low-fitness counterparts. Both the high- and low-aerobic fitness rats showed soleus SERCA uncoupling with exposure to PO. Lastly, no increase in sarcolipin expression in soleus muscle was detected with PO exposure. This dataset implicates muscle uncoupling of SERCA Ca2+ transport and ATP hydrolysis, likely through altered SERCA or sarcolipin function outside of translational regulation, as one contributor to the muscle thermogenesis provoked by exposure to predator threat. These data support the involvement of SERCA uncoupling in both muscle thermogenic induction and enhanced aerobic capacity.

Keywords:  aerobic fitness; futile calcium cycling; high- and low-capacity runners; sarcolipin; uncoupling

DOI:  https://doi.org/10.1152/ajpregu.00173.2022
Mech Ageing Dev. 2022 Sep 07. pii: S0047-6374(22)00112-9. [Epub ahead of print] 111730

Leptin-depended NLRP3 inflammasome activation in osteoarthritic chondrocytes is mediated by ROS.

Evanthia Mourmoura, Ioanna Papathanasiou, Varvara Trachana, Vasilis Konteles, Alexandra Tsoumpou, Andreas Goutas, Aliki-Alexandra Papageorgiou, Nikolaos Stefanou, Aspasia Tsezou.

  Leptin and ROS are implicated in the regulation of inflammatory pathways including NLRP3-inflammasome. We investigated the functional link between leptin, ROS and NLRP3-inflammasome formation/activation in osteoarthritis (OA), an age-related disease. We found that inflammasome components' (NLRP3, ASC, Caspase-1 and cleaved Caspase-1) protein expression were increased in OA cartilage biopsies and chondrocytes compared to healthy cartilage and chondrocytes. Immunofluorescence showed increased co-localization of NLRP3/ASC and NLRP3/Caspase-1, ASC-specks formation and ROS levels in OA compared to normal chondrocytes. NOX4 mRNA expression and IL-1β/IL-18 secretion levels were also elevated in OA chondrocytes. Furthermore, NLRP3-siRNA in OA chondrocytes revealed significant MMP-9/MMP-13 downregulation. To elucidate leptin/ROS/NLRP3-inflammasome interactions, OA chondrocytes were treated with ROS-inhibitor NAC, NOXs-inhibitor DPI, NOX4-inhibitor GLX351322 and leptin-siRNA, while normal chondrocytes were incubated with leptin with or without DPI or GLX351322. We observed attenuated ROS levels and NLRP3-inflammasome formation/activation in NAC-, DPI- or GLX351322-treated OA chondrocytes, while the same effect was shown after transfection with leptin-siRNA. Furthermore, incubation of normal chondrocytes with leptin enhanced ROS production and inflammasome formation/activation, while pretreatment with DPI or GLX351322 abolished leptin's stimulatory effects confirming leptin-NOX4-ROS-inflammasome regulatory axis. Overall, our findings provide novel evidence indicating that leptin-induced NLRP3-inflammasome formation/activation in OA chondrocytes is mediated by NOX4-dependent ROS production.

Keywords:  Osteoarthritis; ROS; chondrocytes; inflammasome; leptin

DOI:  https://doi.org/10.1016/j.mad.2022.111730
Adv Protein Chem Struct Biol. 2022 ;pii: S1876-1623(22)00050-5. [Epub ahead of print]132 49-87

The disturbance of protein synthesis/degradation homeostasis is a common trait of age-related neurodegenerative disorders.

Fabio Di Domenico, Chiara Lanzillotta.

  Protein homeostasis or "proteostasis" represent the process that regulates the balance of the intracellular functional and "healthy" proteins. Proteostasis is fundamental to preserve physiological metabolic processes in the cell and it allow to respond to any given stimulus as the expression of components of the proteostasis network is customized according to the proteomic demands of different cellular environments. In conditions that promote unfolding/misfolding of proteins chaperones act as signaling molecules inducing extreme measures to either fix the problem or destroy unfolded proteins. When the chaperone machinery fails under pathological insults unfolded proteins induce the endoplasmic reticulum (ER) stress activating the unfolded protein response (UPR) machinery. The activation of the UPR restores ER proteostasis primarily through the transcriptional remodeling of ER protein folding, trafficking, and degradation pathways, such as the ubiquitin proteasome system (UPS). If these mechanisms do not manage to clear the aberrant proteins, proteasome overload and become defective, and misfolded proteins may form aggregates thus extending the UPR mechanism. These aggregates are then attempted to be cleared by macroautophagy. Impaired proteostasis promote the accumulation of misfolded proteins that exacerbate the damage to chaperones, surveillance systems and/or degradative activities. Remarkably, the removal of toxic misfolded proteins is critical for all cells, but it is especially significant in neurons since these cannot be readily replaced. In neurons, the maintenance of efficient proteostasis is essential to healthy aging since the dysregulation of the proteostasis network can lead to neurodegenerative disease. Each of these brain pathologies is characterized by the repeated misfolding of one of more peculiar proteins, which evade both the protein folding machinery and cellular degradation mechanisms and begins to form aggregates that nucleate out into large fibrillar aggregates. In this chapter we describe the mechanisms, associated with faulty proteostasis, that promote the formation of protein aggregates, amyloid fibrils, intracellular, and extracellular inclusions in the most common nondegenerative disorders also referred to as protein misfolding disorders.

Keywords:  Alzheimer's disease; Amyotrophic lateral sclerosis; Autophagy; Chaperones; Parkinson's disease; Proteostasis; Ubiquitin proteasome system; Unfolded protein response

DOI:  https://doi.org/10.1016/bs.apcsb.2022.05.008
Am J Forensic Med Pathol. 2022 Sep 13.

Utility of a Handheld Blood Ketone Meter as a Postmortem Indicator of Diabetic Ketoacidosis.

Caris Mitchell, Brandi McCleskey.

ABSTRACT: When investigating a death potentially due to diabetic ketoacidosis (DKA), it is challenging to assess the glucose level in the blood, but β-hydroxybutyrate, the most prevalent ketone body in the blood, is relatively stable after death. The aim of this project is to prove that a commercially available ketone meter can be used on postmortem blood samples to aid the diagnosis of DKA in a novel setting (during coroner/medical examiner examination). Samples with acetone detected via gas chromatography were chosen retrospectively to determine whether the meter could detect ketones in postmortem blood (proof-of-concept). In all of the thawed samples, the meter detected an elevated ketone level. Samples were then obtained in a prospective manner to include those with a possible cause of death from DKA along with controls. We correctly identified 16 cases in which death was due to DKA with use of the ketone manner. The ketone levels ranged from 2.6 to 5.4 mmol/L in those cases. The diagnosis was confirmed with a greatly elevated vitreous glucose concentration or glycated hemoglobin concentration. Detecting the presence of ketones while in the autopsy suite allowed for more accurate preliminary diagnoses and utilization of resources.

DOI: https://doi.org/10.1097/PAF.0000000000000794
Bull Math Biol. 2022 Sep 17. 84(11): 123

Computational Model of the Effect of Mitochondrial Dysfunction on Excitation-Contraction Coupling in Skeletal Muscle.

Sageanne Senneff, Madeleine M Lowery.

  It has become well established that mitochondria not only regulate myoplasmic calcium in skeletal muscle, but also use that calcium to stimulate oxidative phosphorylation (OXPHOS). While experimental approaches have allowed for imaging of mitochondrial calcium and membrane potentials in isolated fibers, capturing the role of mitochondria and the impact of mitochondrial impairments on excitation-contraction coupling (ECC) remains difficult to explore in intact muscle. Computational models have been widely used to examine the structure and function of skeletal muscle contraction; however, models of ECC to date lack communication between the myoplasm and mitochondria for regulating calcium and ATP during sustained contractions. To address this, a mathematical model of mitochondrial calcium handling and OXPHOS was integrated into a physiological model of ECC incorporating action potential propagation, calcium handling between the sarcoplasmic reticulum (SR) and the myoplasm, and crossbridge cycling. The model was used to examine the protective role of mitochondria during repeated stimulation and the impact of mitochondrial dysfunction on ECC resulting from progressive OXPHOS inhibition. Pathological myoplasmic calcium accumulation occurred through distinct mechanisms in the model in the case of either electron transport chain, F1F0 ATP synthase, or adenine nucleotide transporter impairments. To investigate the effect of each impairment on force, a model of calcium-stimulated apoptosis was utilized to capture dysfunction-induced reductions in muscle mass, driving whole muscle force loss. The model presented in this study can be used to examine the role of mitochondria in the regulation of calcium, ATP, and force generation during voluntary contraction.

Keywords:  Apoptosis; Calcium dynamics; Force; Mathematical modeling; Muscle weakness

DOI:  https://doi.org/10.1007/s11538-022-01079-3
Front Vet Sci. 2022 ;9 925900

β-hydroxybutyrate impairs monocyte function via the ROS-NLR family pyrin domain-containing three inflammasome (NLRP3) pathway in ketotic cows.

Zhihao Dong, Xudong Sun, Yan Tang, Shengbin Luo, Hongdou Jia, Qiushi Xu, Qianming Jiang, Juan J Loor, Wei Xu, Chuang Xu.

  Cows with ketosis display severe metabolic stress and immune dysfunction which renders them more susceptible to infections. Monocytes, one of the major subtypes of white blood cells, play an important role in innate immune defense against infections. Thus, the aim of this study was to investigate alterations in immune function, reactive oxygen species (ROS) production and activity of the NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway in monocytes (CD14+) of cows with clinical ketosis (CK). Twelve healthy multiparous Holstein cows [blood β-hydroxybutyrate (BHB) concentration < 1.2 mM] and 12 cows with CK (BHB > 3.0 mM) at 3 to 14 days in milk were used for blood sample collection. To determine effects of BHB on phagocytosis, ROS and protein abundance of the NLRP3 inflammasome pathway in vitro, monocytes isolated from healthy cows were treated with 3.0 mM BHB for 0, 6, 12 or 24 h. Dry matter intake (22.7 vs. 19.0 kg) was lower in cows with CK. Serum concentrations of fatty acids (0.30 vs. 0.88 mM) and BHB (0.52 vs. 3.78 mM) were greater in cows with CK, whereas concentration of glucose was lower (4.09 vs. 2.23 mM). The adhesion, migration and phagocytosis of monocytes were lower in cows with CK, but apoptosis and ROS content were greater. Protein abundance of NLRP3, cysteinyl aspartate specific proteinase 1 (caspase 1) and interleukin-1B p17 (IL1B p17) were greater in monocytes of cows with CK, while abundance of NADPH oxidase isoform 2 (NOX2) was lower. Compared with 0 h BHB, ROS content and apoptosis were greater in the monocytes challenged for 6, 12 or 24 h BHB. Compared with 0 h BHB, protein abundance of NLRP3, caspase 1, IL1B p17 and concentration of IL1B in medium were greater in the monocytes challenged for 6, 12 or 24 h BHB. However, compared with 0 h BHB, protein abundance of NOX2 and phagocytosis of monocytes were lower in the monocytes challenged for 6, 12 or 24 h BHB. Overall, the data suggested that exogenous BHB activated the ROS-NLRP3 pathway, which might be partly responsible for immune dysfunction of dairy cows with CK.

Keywords:  ketosis; monocytes; oxidative stress; phagocytosis; β-hydroxybutyric acid

DOI:  https://doi.org/10.3389/fvets.2022.925900