Integrating Clinical Phenotype With Multiomics Analyses of Human Cardiac Tissue Unveils Divergent Metabolic Remodeling in Genotype-Positive and Genotype-Negative Patients With Hypertrophic Cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is caused by sarcomere gene mutations (genotype-positive HCM) in ≈50% of patients and occurs in the absence of mutations (genotype-negative HCM) in the other half of patients. We explored how alterations in the metabolomic and lipidomic landscape are involved in cardiac remodeling in both patient groups. METHODS: We performed proteomics, metabolomics, and lipidomics on myectomy samples (genotype-positive N=19; genotype-negative N=22; and genotype unknown N=6) from clinically well-phenotyped patients with HCM and on cardiac tissue samples from sex- and age-matched and body mass index-matched nonfailing donors (N=20). These data sets were integrated to comprehensively map changes in lipid-handling and energy metabolism pathways. By linking metabolomic and lipidomic data to variability in clinical data, we explored patient group-specific associations between cardiac and metabolic remodeling. RESULTS: HCM myectomy samples exhibited (1) increased glucose and glycogen metabolism, (2) downregulation of fatty acid oxidation, and (3) reduced ceramide formation and lipid storage. In genotype-negative patients, septal hypertrophy and diastolic dysfunction correlated with lowering of acylcarnitines, redox metabolites, amino acids, pentose phosphate pathway intermediates, purines, and pyrimidines. In contrast, redox metabolites, amino acids, pentose phosphate pathway intermediates, purines, and pyrimidines were positively associated with septal hypertrophy and diastolic impairment in genotype-positive patients. CONCLUSIONS: We provide novel insights into both general and genotype-specific metabolic changes in HCM. Distinct metabolic alterations underlie cardiac disease progression in genotype-negative and genotype-positive patients with HCM.

A cohort study of 19 patients with gyrate atrophy of the choroid and retina (GACR).

PURPOSE: Gyrate atrophy of the choroid and retina (GACR) is an autosomal recessive inherited metabolic disorder (IMD) characterised by progressive retinal degeneration, leading to severe visual impairment. The rapid developments in ophthalmic genetic therapies warrant knowledge on clinical phenotype of eligible diseases such as GACR to define future therapeutic parameters in clinical trials. METHODS: Retrospective chart analysis was performed in nineteen patients. Data were analysed using IBM SPSS Statistics version 28.0.1.1. RESULTS: Nineteen patients were included with a mean age of 32.6 years (range 8-58). Mean age at onset of ophthalmic symptoms was 7.9 years (range 3-16). Median logMAR of visual acuity at inclusion was 0.26 (range -0.18-3.00). Mean age at cataract surgery was 28.8 years (n = 11 patients). Mean spherical equivalent of the refractive error was -8.96 (range -20.87 to -2.25). Cystoid maculopathy was present in 68% of patients, with a loss of integrity of the foveal ellipsoid zone (EZ) in 24/38 eyes. Of the 14 patients treated with dietary protein restriction, the four patients who started the diet before age 10 showed most benefit. CONCLUSION: This study demonstrates the severe ophthalmic disease course associated with GACR, as well as possible benefit of early dietary treatment. In addition to visual loss, patients experience severe myopia, early-onset cataract, and CME. There is a loss of foveal EZ integrity at a young age, emphasising the need for early diagnosis enabling current and future therapeutic interventions.

Upregulation of the AMPK-FOXO1-PDK4 pathway is a primary mechanism of pyruvate dehydrogenase activity reduction in tafazzin-deficient cells.

Barth syndrome (BTHS) is a rare disorder caused by mutations in the TAFAZZIN gene. Previous studies from both patients and model systems have established metabolic dysregulation as a core component of BTHS pathology. In particular, features such as lactic acidosis, pyruvate dehydrogenase (PDH) deficiency, and aberrant fatty acid and glucose oxidation have been identified. However, the lack of a mechanistic understanding of what causes these conditions in the context of BTHS remains a significant knowledge gap, and this has hindered the development of effective therapeutic strategies for treating the associated metabolic problems. In the current study, we utilized tafazzin-knockout C2C12 mouse myoblasts (TAZ-KO) and cardiac and skeletal muscle tissue from tafazzin-knockout mice to identify an upstream mechanism underlying impaired PDH activity in BTHS. This mechanism centers around robust upregulation of pyruvate dehydrogenase kinase 4 (PDK4), resulting from hyperactivation of AMP-activated protein kinase (AMPK) and subsequent transcriptional upregulation by forkhead box protein O1 (FOXO1). Upregulation of PDK4 in tafazzin-deficient cells causes direct phospho-inhibition of PDH activity accompanied by increased glucose uptake and elevated intracellular glucose concentration. Collectively, our findings provide a novel mechanistic framework whereby impaired tafazzin function ultimately results in robust PDK4 upregulation, leading to impaired PDH activity and likely linked to dysregulated metabolic substrate utilization. This mechanism may underlie previously reported findings of BTHS-associated metabolic dysregulation.

Four-dimensional lipidomics profiling in X-linked adrenoleukodystrophy using trapped ion mobility mass spectrometry.

Lipids play pivotal roles in an extensive range of metabolic and physiological processes. In recent years, the convergence of trapped ion mobility spectrometry and MS has enabled 4D-lipidomics, a highly promising technology for comprehensive lipid analysis. 4D-lipidomics assesses lipid annotations across four distinct dimensions-retention time, collisional cross section, m/z (mass-to-charge ratio), and MS/MS spectra-providing a heightened level of confidence in lipid annotation. These advantages prove particularly valuable when investigating complex disorders involving lipid metabolism, such as adrenoleukodystrophy (ALD). ALD is characterized by the accumulation of very-long-chain fatty acids (VLCFAs) due to pathogenic variants in the ABCD1 gene. A comprehensive 4D-lipidomics strategy of ALD fibroblasts demonstrated significant elevations of various lipids from multiple classes. This indicates that the changes observed in ALD are not confined to a single lipid class and likely impacts a broad spectrum of lipid-mediated physiological processes. Our findings highlight the incorporation of mainly saturated and monounsaturated VLCFA variants into a range of lipid classes, encompassing phosphatidylcholines, triacylglycerols, and cholesterol esters. These include ultra-long-chain fatty acids with a length of up to thirty carbon atoms. Lipid species containing C26:0 and C26:1 were the most frequently detected VLCFA lipids in our study. Furthermore, we report a panel of 121 new candidate biomarkers in fibroblasts, exhibiting significant differentiation between controls and individuals with ALD. In summary, this study demonstrates the capabilities of a 4D-lipid profiling workflow in unraveling novel insights into the intricate lipid modifications associated with metabolic disorders like ALD.

Low-dose naltrexone extends healthspan and lifespan in C. elegans via SKN-1 activation.

As the global aging population rises, finding effective interventions to improve aging health is crucial. Drug repurposing, utilizing existing drugs for new purposes, presents a promising strategy for rapid implementation. We explored naltrexone from the Library of Integrated Network-based Cellular Signatures (LINCS) based on several selection criteria. Low-dose naltrexone (LDN) has gained attention for treating various diseases, yet its impact on longevity remains underexplored. Our study on C. elegans demonstrated that a low dose, but not high dose, of naltrexone extended the healthspan and lifespan. This effect was mediated through SKN-1 (NRF2 in mammals) signaling, influencing innate immune gene expression and upregulating oxidative stress responses. With LDN's low side effects profile, our findings underscore its potential as a geroprotector, suggesting further exploration for promoting healthy aging in humans is warranted.

A conserved complex lipid signature marks human muscle aging and responds to short-term exercise.

Studies in preclinical models suggest that complex lipids, such as phospholipids, play a role in the regulation of longevity. However, identification of universally conserved complex lipid changes that occur during aging, and how these respond to interventions, is lacking. Here, to comprehensively map how complex lipids change during aging, we profiled ten tissues in young versus aged mice using a lipidomics platform. Strikingly, from >1,200 unique lipids, we found a tissue-wide accumulation of bis(monoacylglycero)phosphate (BMP) during mouse aging. To investigate translational value, we assessed muscle tissue of young and older people, and found a similar marked BMP accumulation in the human aging lipidome. Furthermore, we found that a healthy-aging intervention consisting of moderate-to-vigorous exercise was able to lower BMP levels in postmenopausal female research participants. Our work implicates complex lipid biology as central to aging, identifying a conserved aging lipid signature of BMP accumulation that is modifiable upon a short-term healthy-aging intervention.

CIAO1 and MMS19 deficiency: A lethal neurodegenerative phenotype caused by cytosolic Fe-S cluster protein assembly disorders.

PURPOSE: The functionality of many cellular proteins depends on cofactors; yet, they have only been implicated in a minority of Mendelian diseases. Here, we describe the first 2 inherited disorders of the cytosolic iron-sulfur protein assembly system. METHODS: Genetic testing via genome sequencing was applied to identify the underlying disease cause in 3 patients with microcephaly, congenital brain malformations, progressive developmental and neurologic impairments, recurrent infections, and a fatal outcome. Studies in patient-derived skin fibroblasts and zebrafish models were performed to investigate the biochemical and cellular consequences. RESULTS: Metabolic analysis showed elevated uracil and thymine levels in body fluids but no pathogenic variants in DPYD, encoding dihydropyrimidine dehydrogenase. Genome sequencing identified compound heterozygosity in 2 patients for missense variants in CIAO1, encoding cytosolic iron-sulfur assembly component 1, and homozygosity for an in-frame 3-nucleotide deletion in MMS19, encoding the MMS19 homolog, cytosolic iron-sulfur assembly component, in the third patient. Profound alterations in the proteome, metabolome, and lipidome were observed in patient-derived fibroblasts. We confirmed the detrimental effect of deficiencies in CIAO1 and MMS19 in zebrafish models. CONCLUSION: A general failure of cytosolic and nuclear iron-sulfur protein maturation caused pleiotropic effects. The critical function of the cytosolic iron-sulfur protein assembly machinery for antiviral host defense may well explain the recurrent severe infections occurring in our patients.

Upregulation of the AMPK-FOXO1-PDK4 pathway is a primary mechanism of pyruvate dehydrogenase activity reduction and leads to increased glucose uptake in tafazzin-deficient cells.

Barth syndrome (BTHS) is a rare disorder caused by mutations in the TAFAZZIN gene. Previous studies from both patients and model systems have established metabolic dysregulation as a core component of BTHS pathology. In particular, features such as lactic acidosis, pyruvate dehydrogenase (PDH) deficiency, and aberrant fatty acid and glucose oxidation have been identified. However, the lack of a mechanistic understanding of what causes these conditions in the context of BTHS remains a significant knowledge gap, and this has hindered the development of effective therapeutic strategies for treating the associated metabolic problems. In the current study, we utilized tafazzin-knockout C2C12 mouse myoblasts (TAZ-KO) and cardiac and skeletal muscle tissue from tafazzin-knockout mice to identify an upstream mechanism underlying impaired PDH activity in BTHS. This mechanism centers around robust upregulation of pyruvate dehydrogenase kinase 4 (PDK4), resulting from hyperactivation of AMP-activated protein kinase (AMPK) and subsequent transcriptional upregulation by forkhead box protein O1 (FOXO1). Upregulation of PDK4 in tafazzin-deficient cells causes direct phospho-inhibition of PDH activity accompanied by increased glucose uptake and elevated intracellular glucose concentration. Collectively, our findings provide a novel mechanistic framework whereby impaired tafazzin function ultimately results in robust PDK4 upregulation, leading to impaired PDH activity and likely linked to dysregulated metabolic substrate utilization. This mechanism may underlie previously reported findings of BTHS-associated metabolic dysregulation.

Tracer-based lipidomics enables the discovery of disease-specific candidate biomarkers in mitochondrial ß-oxidation disorders.

Carnitine derivatives of disease-specific acyl-CoAs are the diagnostic hallmark for long-chain fatty acid ß-oxidation disorders (lcFAOD), including carnitine shuttle deficiencies, very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD), long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) and mitochondrial trifunctional protein deficiency (MPTD). The exact consequence of accumulating lcFAO-intermediates and their influence on cellular lipid homeostasis is, however, still unknown. To investigate the fate and cellular effects of the accumulating lcFAO-intermediates and to explore the presence of disease-specific markers, we used tracer-based lipidomics with deuterium-labeled oleic acid (D9-C18:1) in lcFAOD patient-derived fibroblasts. In line with previous studies, we observed a trend towards neutral lipid accumulation in lcFAOD. In addition, we detected a direct connection between the chain length and patterns of (un)saturation of accumulating acylcarnitines and the various enzyme deficiencies. Our results also identified two disease-specific candidate biomarkers. Lysophosphatidylcholine(14:1) (LPC(14:1)) was specifically increased in severe VLCADD compared to mild VLCADD and control samples. This was confirmed in plasma samples showing an inverse correlation with enzyme activity, which was better than the classic diagnostic marker C14:1-carnitine. The second candidate biomarker was an unknown lipid class, which we identified as S-(3-hydroxyacyl)cysteamines. We hypothesized that these were degradation products of the CoA moiety of accumulating 3-hydroxyacyl-CoAs. S-(3-hydroxyacyl)cysteamines were significantly increased in LCHADD compared to controls and other lcFAOD, including MTPD. Our findings suggest extensive alternative lipid metabolism in lcFAOD and confirm that lcFAOD accumulate neutral lipid species. In addition, we present two disease-specific candidate biomarkers for VLCADD and LCHADD, that may have significant relevance for disease diagnosis, prognosis, and monitoring.

Doxycycline induces mitochondrial dysfunction in aortic smooth muscle cells.

The antibiotic doxycycline is known to inhibit inflammation and was therefore considered as a therapeutic to prevent abdominal aortic aneurysm (AAA) growth. Yet mitochondrial dysfunction is a key-characteristic of clinical AAA disease. We hypothesize that doxycycline impairs mitochondrial function in the aorta and aortic smooth muscle cells (SMCs). Doxycycline induced mitonuclear imbalance, reduced proliferation and diminished expression of typical contractile smooth muscle cell (SMC) proteins. To understand the underlying mechanism, we studied krüppel-like factor 4 (KLF4). The expression of this transcription factor was enhanced in SMCs after doxycycline treatment. Knockdown of KLF4, however, did not affect the doxycycline-induced SMC phenotypic changes. Then we used the bioenergetics drug elamipretide (SS-31). Doxycycline-induced loss of SMC contractility markers was not rescued, but mitochondrial genes and mitochondrial connectivity improved upon elamipretide. Thus while doxycycline is anti-inflammatory, it also induces mitochondrial dysfunction in aortic SMCs and causes SMC phenotypic switching, potentially contributing to aortic aneurysm pathology. The drug elamipretide helps mitigate the harmful effects of doxycycline on mitochondrial function in aortic SMC, and may be of interest for treatment of aneurysm diseases with pre-existing mitochondrial dysfunction.

HDAC1/2 inhibitor therapy improves multiple organ systems in aged mice.

Aging increases the risk of age-related diseases, imposing substantial healthcare and personal costs. Targeting fundamental aging mechanisms pharmacologically can promote healthy aging and reduce this disease susceptibility. In this work, we employed transcriptome-based drug screening to identify compounds emulating transcriptional signatures of long-lived genetic interventions. We discovered compound 60 (Cmpd60), a selective histone deacetylase 1 and 2 (HDAC1/2) inhibitor, mimicking diverse longevity interventions. In extensive molecular, phenotypic, and bioinformatic assessments using various cell and aged mouse models, we found Cmpd60 treatment to improve age-related phenotypes in multiple organs. Cmpd60 reduces renal epithelial-mesenchymal transition and fibrosis in kidney, diminishes dementia-related gene expression in brain, and enhances cardiac contractility and relaxation for the heart. In sum, our two-week HDAC1/2 inhibitor treatment in aged mice establishes a multi-tissue, healthy aging intervention in mammals, holding promise for therapeutic translation to promote healthy aging in humans.

High-content phenotypic analysis of a C. elegans recombinant inbred population identifies genetic and molecular regulators of lifespan.

Lifespan is influenced by complex interactions between genetic and environmental factors. Studying those factors in model organisms of a single genetic background limits their translational value for humans. Here, we mapped lifespan determinants in 85 genetically diverse C. elegans recombinant intercross advanced inbred lines (RIAILs). We assessed molecular profiles - transcriptome, proteome, and lipidome - and life-history traits, including lifespan, development, growth dynamics, and reproduction. RIAILs exhibited large variations in lifespan, which positively correlated with developmental time. Among the top candidates obtained from multi-omics data integration and QTL mapping, we validated known and novel longevity modulators, including rict-1, gfm-1 and mltn-1. We translated their relevance to humans using UK Biobank data and showed that variants in RICTOR and GFM1 are associated with an elevated risk of age-related heart disease, dementia, diabetes, kidney, and liver diseases. We organized our dataset as a resource (https://lisp-lms.shinyapps.io/RIAILs/) that allows interactive explorations for new longevity targets.

Vision on gyrate atrophy: why treat the eye?

In the April issue of this Journal, Boffa and coworkers put forward a new therapeutic approach for Gyrate Atrophy of the Choroid and Retina (GACR; OMIM 258870) (Boffa et al, 2023). The authors propose to apply gene therapy to the liver for GACR, a metabolic disease primarily affecting eyesight due to retinal degeneration. Their vision is enthusiastically supported by a News and Views comment in the same issue (Seker Yilmaz and Gissen, 2023). However, based on disease pathology, patient's needs, ethical considerations, therapeutic developmental time lines, and current state of the art of gene therapy for liver and eye, we have a different view on this issue: We argue below that local treatment of the eye is the preferred option for GACR.

Ophthalmic acid is a glutathione regulating tripeptide.

Since its discovery in 1958 in the lens of cows, ophthalmic acid (OPH) has stood in the shadow of its anti-oxidant analog: glutathione (GSH). Lacking the thiol group that gives GSH many of its important properties, ophthalmic acid's function has remained elusive, and it has been widely presumed to be an accidental product of the same enzymes. In this review, we compile evidence demonstrating that OPH is a ubiquitous metabolite found in bacteria, plants, fungi, and animals, produced through several layers of metabolic regulation. We discuss the limitations of the oft-repeated suggestions that aberrations in OPH levels should solely indicate GSH deficiency or oxidative stress. Finally, we discuss the available literature and suggest OPH's role in metabolism as a GSH-regulating tripeptide; controlling both cellular and organelle influx and efflux of GSH, as well as modulating GSH-dependent reactions and signaling. Ultimately, we hope that this review reinvigorates and directs more research into this versatile metabolite.

Platelets of COVID-19 patients display mitochondrial dysfunction, oxidative stress, and energy metabolism failure compatible with cell death.

Background: Alterations in platelet function have been implicated in the pathophysiology of COVID-19 since the beginning of the pandemic. While early reports linked hyperactivated platelets to thromboembolic events in COVID-19, subsequent investigations demonstrated hyporeactive platelets with a procoagulant phenotype. Mitochondria are important for energy metabolism and the function of platelets. Objectives: Here, we sought to map the energy metabolism of platelets in a cohort of noncritically ill COVID-19 patients and assess platelet mitochondrial function, activation status, and responsiveness to external stimuli. Methods: We enrolled hospitalized COVID-19 patients and controls between October 2020 and December 2021. Platelets function and metabolism was analyzed by flow cytometry, metabolomics, glucose fluxomics, electron and fluorescence microscopy and western blot. Results: Platelets from COVID-19 patients showed increased phosphatidylserine externalization indicating a procoagulant phenotype and hyporeactivity to ex vivo stimuli, associated with profound mitochondrial dysfunction characterized by mitochondrial depolarization, lower mitochondrial DNA-encoded transcript levels, an altered mitochondrial morphology consistent with increased mitochondrial fission, and increased pyruvate/lactate ratios in platelet supernatants. Metabolic profiling by untargeted metabolomics revealed NADH, NAD+, and ATP among the top decreased metabolites in patients' platelets, suggestive of energy metabolism failure. Consistently, platelet fluxomics analyses showed a strongly reduced utilization of 13C-glucose in all major energy pathways together with a rerouting of glucose to de novo generation of purine metabolites. Patients' platelets further showed evidence of oxidative stress, together with increased glutathione oxidation and synthesis. Addition of plasma from COVID-19 patients to normal platelets partially reproduced the phenotype of patients' platelets and disclosed a temporal relationship between mitochondrial decay and (subsequent) phosphatidylserine exposure and hyporeactivity. Conclusion: These data link energy metabolism failure in platelets from COVID-19 patients with a prothrombotic platelet phenotype with features matching cell death.

Repurposing nucleoside reverse transcriptase inhibitors (NRTIs) to slow aging.

Repurposing drugs already approved in the clinic to be used off-label as geroprotectors, compounds that combat mechanisms of aging, are a promising way to rapidly reduce age-related disease incidence in society. Several recent studies have found that a class of drugs-nucleoside reverse transcriptase inhibitors (NRTIs)-originally developed as treatments for cancers and human immunodeficiency virus (HIV) infection, could be repurposed to slow the aging process. Interestingly, these studies propose complementary mechanisms that target multiple hallmarks of aging. At the molecular level, NRTIs repress LINE-1 elements, reducing DNA damage, benefiting the hallmark of aging of 'Genomic Instability'. At the organellar level, NRTIs inhibit mitochondrial translation, activate ATF-4, suppress cytosolic translation, and extend lifespan in worms in a manner related to the 'Loss of Proteostasis' hallmark of aging. Meanwhile, at the cellular level, NRTIs inhibit the P2X7-mediated activation of the inflammasome, reducing inflammation and improving the hallmark of aging of 'Altered Intercellular Communication'. Future development of NRTIs for human aging health will need to balance out toxic side effects with the beneficial effects, which may occur in part through hormesis.

Human ovarian aging is characterized by oxidative damage and mitochondrial dysfunction.

STUDY QUESTION: Are human ovarian aging and the age-related female fertility decline caused by oxidative stress and mitochondrial dysfunction in oocytes? SUMMARY ANSWER: We found oxidative damage in oocytes of advanced maternal age, even at the primordial follicle stage, and confirmed mitochondrial dysfunction in such oocytes, which likely resulted in the use of alternative energy sources. WHAT IS KNOWN ALREADY: Signs of reactive oxygen species-induced damage and mitochondrial dysfunction have been observed in maturing follicles, and even in early stages of embryogenesis. However, although recent evidence indicates that also primordial follicles have metabolically active mitochondria, it is still often assumed that these follicles avoid oxidative phosphorylation to prevent oxidative damage in dictyate arrested oocytes. Data on the influence of ovarian aging on oocyte metabolism and mitochondrial function are still limited. STUDY DESIGN, SIZE, DURATION: A set of 39 formalin-fixed and paraffin-embedded ovarian tissue biopsies were divided into different age groups and used for immunofluorescence analysis of oxidative phosphorylation activity and oxidative damage to proteins, lipids, and DNA. Additionally, 150 immature oocytes (90 germinal vesicle oocytes and 60 metaphase I oocytes) and 15 cumulus cell samples were divided into different age groups and used for targeted metabolomics and lipidomics analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: Ovarian tissues used for immunofluorescence microscopy were collected through PALGA, the nationwide network, and registry of histo- and cytopathology in The Netherlands. Comprehensive metabolomics and lipidomics were performed by liquid-liquid extraction and full-scan mass spectrometry, using oocytes and cumulus cells of women undergoing ICSI treatment based on male or tubal factor infertility, or fertility preservation for non-medical reasons. MAIN RESULTS AND THE ROLE OF CHANCE: Immunofluorescence imaging on human ovarian tissue indicated oxidative damage by protein and lipid (per)oxidation already at the primordial follicle stage. Metabolomics and lipidomics analysis of oocytes and cumulus cells in advanced maternal-age groups demonstrated a shift in the glutathione-to-oxiglutathione ratio and depletion of phospholipids. Age-related changes in polar metabolites suggested a decrease in mitochondrial function, as demonstrated by NAD+, purine, and pyrimidine depletion, while glycolysis substrates and glutamine accumulated, with age. Oocytes from women of advanced maternal age appeared to use alternative energy sources like glycolysis and the adenosine salvage pathway, and possibly ATP which showed increased production in cumulus cells. LIMITATIONS, REASONS FOR CAUTION: The immature oocytes used in this study were all subjected to ovarian stimulation with high doses of follicle-stimulating hormones, which might have concealed some age-related differences. WIDER IMPLICATIONS OF THE FINDINGS: Further studies on how to improve mitochondrial function, or lower oxidative damage, in oocytes from women of advanced maternal age, for instance by supplementation of NAD+ precursors to promote mitochondrial biogenesis, are warranted. In addition, supplementing the embryo medium of advanced maternal-age embryos with such compounds could be a treatment option worth exploring. STUDY FUNDING/COMPETING INTEREST(S): The study was funded by the Amsterdam UMC. The authors declare to have no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Mitochondria-associated programmed cell death as a therapeutic target for age-related disease.

Mitochondria, ubiquitous double-membrane-bound organelles, regulate energy production, support cellular activities, harbor metabolic pathways, and, paradoxically, mediate cell fate. Evidence has shown mitochondria as points of convergence for diverse cell death-inducing pathways that trigger the various mechanisms underlying apoptotic and nonapoptotic programmed cell death. Thus, dysfunctional cellular pathways eventually lead or contribute to various age-related diseases, such as neurodegenerative, cardiovascular and metabolic diseases. Thus, mitochondrion-associated programmed cell death-based treatments show great therapeutic potential, providing novel insights in clinical trials. This review discusses mitochondrial quality control networks with activity triggered by stimuli and that maintain cellular homeostasis via mitohormesis, the mitochondrial unfolded protein response, and mitophagy. The review also presents details on various forms of mitochondria-associated programmed cell death, including apoptosis, necroptosis, ferroptosis, pyroptosis, parthanatos, and paraptosis, and highlights their involvement in age-related disease pathogenesis, collectively suggesting therapeutic directions for further research.

Inflammatory and glycolytic programs underpin a primed blood neutrophil state in patients with pneumonia.

Neutrophils are potent immune cells with key antimicrobial functions. Previous in vitro work has shown that neutrophil effector functions are mainly fueled by intracellular glycolysis. Little is known about the state of neutrophils still in the circulation in patients during infection. Here, we combined flow cytometry, stimulation assays, transcriptomics, and metabolomics to investigate the link between inflammatory and metabolic pathways in blood neutrophils of patients with community-acquired pneumonia. Patients' neutrophils, relative to neutrophils from age- and sex- matched controls, showed increased degranulation upon ex vivo stimulation, and portrayed distinct upregulation of inflammatory transcriptional programs. This neutrophil phenotype was accompanied by a high-energy state with increased intracellular ATP content, and transcriptomic and metabolic upregulation of glycolysis and glycogenolysis. One month after hospital admission, these metabolic and transcriptomic changes were largely normalized. These data elucidate the molecular programs that underpin a balanced, yet primed state of blood neutrophils during pneumonia.