Uridine and pyruvate protect T cells' proliferative capacity from mitochondrial toxic antibiotics: a clinical pilot study

Single-cell multi-omics of mitochondrial DNA disorders reveals dynamics of purifying selection across human immune cells

Pathogenic mutations in mitochondrial DNA (mtDNA) compromise cellular metabolism, contributing to cellular heterogeneity and disease. Diverse mutations are associated with diverse clinical phenotypes, suggesting distinct organ- and cell-type-specific metabolic vulnerabilities. Here we establish a multi-omics approach to quantify deletions in mtDNA alongside cell state features in single cells derived from six patients across the phenotypic spectrum of single large-scale mtDNA deletions (SLSMDs). By profiling 206,663 cells, we reveal the dynamics of pathogenic mtDNA deletion heteroplasmy consistent with purifying selection and distinct metabolic vulnerabilities across T-cell states in vivo and validate these observations in vitro. By extending analyses to hematopoietic and erythroid progenitors, we reveal mtDNA dynamics and cell-type-specific gene regulatory adaptations, demonstrating the context-dependence of perturbing mitochondrial genomic integrity. Collectively, we report pathogenic mtDNA heteroplasmy dynamics of individual blood and immune cells across lineages, demonstrating the power of single-cell multi-omics for revealing fundamental properties of mitochondrial genetics.

Pyruvate and uridine rescue the metabolic profile of OXPHOS dysfunction

Introduction

Primary mitochondrial diseases (PMD) are a large, heterogeneous group of genetic disorders affecting mitochondrial function, mostly by disrupting the oxidative phosphorylation (OXPHOS) system. Understanding the cellular metabolic re-wiring occurring in PMD is crucial for the development of novel diagnostic tools and treatments, as PMD are often complex to diagnose and most of them currently have no effective therapy.

Objectives

To characterize the cellular metabolic consequences of OXPHOS dysfunction and based on the metabolic signature, to design new diagnostic and therapeutic strategies.

Methods

In vitro assays were performed in skin-derived fibroblasts obtained from patients with diverse PMD and validated in pharmacological models of OXPHOS dysfunction. Proliferation was assessed using the Incucyte technology. Steady-state glucose and glutamine tracing studies were performed with LC-MS quantification of cellular metabolites. The therapeutic potential of nutritional supplements was evaluated by assessing their effect on proliferation and on the metabolomics profile. Successful therapies were then tested in a in vivo lethal rotenone model in zebrafish.

Results

OXPHOS dysfunction has a unique metabolic signature linked to an NAD+/NADH imbalance including depletion of TCA intermediates and aspartate, and increased levels of glycerol-3-phosphate. Supplementation with pyruvate and uridine fully rescues this altered metabolic profile and the subsequent proliferation deficit. Additionally, in zebrafish, the same nutritional treatment increases the survival after rotenone exposure.

Conclusions

Our findings reinforce the importance of the NAD+/NADH imbalance following OXPHOS dysfunction in PMD and open the door to new diagnostic and therapeutic tools for PMD.

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OXPHOS deficiency causes a distinct metabolic profile linked to a NAD+/NADH imbalance.

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Depleted intracellular aspartic acid is a potential biomarker for OXPHOS dysfunction.

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Therapy with pyruvate and uridine corrects the metabolic profile of OXPHOS deficiency.

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Pyruvate and uridine treatment increases survival in a lethal rotenone zebrafish model.

Impaired Lymphocyte Responses in Pediatric Sepsis Vary by Pathogen Type and are Associated with Features of Immunometabolic Dysregulation

BACKGROUND

Sepsis is the leading cause of death in hospitalized children worldwide. Despite its hypothesized immune-mediated mechanism, targeted immunotherapy for sepsis is not available for clinical use.

OBJECTIVE

To determine the association between longitudinal cytometric, proteomic, bioenergetic, and metabolomic markers of immunometabolic dysregulation and pathogen type in pediatric sepsis.

METHODS

Serial peripheral blood mononuclear cell (PBMC) samples were obtained from 14 sepsis patients (34 total samples) and 7 control patients for this observational study. Flow cytometry was used to define immunophenotype, including T cell subset frequency and activation state, and assess intracellular cytokine production. Global immune dysfunction was assessed by tumor necrosis factor-α (TNF-α) production capacity and monocyte human leukocyte antigen DR (HLA-DR) expression. Mitochondrial function was assessed by bulk respirometry. Plasma cytokine levels were determined via Luminex assay. Metabolites were measured by liquid chromatography-mass spectrometry. Results were compared by timepoint and pathogen type.

RESULTS

Sepsis patients were older (15.9 years vs. 10.4 years, P = 0.02) and had higher illness severity by PRISM-III (12.0 vs. 2.0, P < 0.001) compared to controls; demographics were otherwise similar, though control patients were predominately male. Compared to controls, sepsis patients at timepoint 1 demonstrated lower monocyte HLA-DR expression (75% vs. 92%, P = 0.02), loss of peripheral of non-naïve CD4+ T cells (62.4% vs. 77.6%, P = 0.04), and reduced PBMC mitochondrial spare residual capacity (SRC; 4.0 pmol/s/106 cells vs. 8.4 pmol/s/106 cells, P = 0.01). At sepsis onset, immunoparalysis (defined as TNF-α production capacity < 200 pg/mL) was present in 39% of sepsis patients and not identified among controls. Metabolomic findings in sepsis patients were most pronounced at sepsis onset and included elevated uridine and 2-dehydrogluconate and depleted citrulline. Loss of peripheral non-naïve CD4+ T cells was associated with immune dysfunction and reduced cytokine production despite increased T cell activation. CD4+ T cell differentiation and corresponding pro- and anti-inflammatory cytokines varied by pathogen.

CONCLUSION

Pediatric sepsis patients exhibit a complex, dynamic physiologic state characterized by impaired T cell function and immunometabolic dysregulation which varies by pathogen type.

Effects of Sodium Pyruvate on Vanadyl Sulphate-Induced Reactive Species Generation and Mitochondrial Destabilisation in CHO-K1 Cells

Vanadium is ranked as one of the world’s critical metals considered important for economic growth with wide use in the steel industry. However, its production, applications, and emissions related to the combustion of vanadium-containing fuels are known to cause harm to the environment and human health. Pyruvate, i.e., a glucose metabolite, has been postulated as a compound with multiple cytoprotective properties, including antioxidant and anti-inflammatory effects. The aim of the present study was to examine the antioxidant potential of sodium pyruvate (4.5 mM) in vanadyl sulphate (VOSO₄)-exposed CHO-K1 cells. Dichloro-dihydro-fluorescein diacetate and dihydrorhodamine 123 staining were performed to measure total and mitochondrial generation of reactive oxygen species (ROS), respectively. Furthermore, mitochondrial damage was investigated using MitoTell orange and JC-10 staining assays. We demonstrated that VOSO₄ alone induced a significant rise in ROS starting from 1 h to 3 h after the treatment. Additionally, after 24 and 48 h of exposure, VOSO₄ elicited both extensive hyperpolarisation and depolarisation of the mitochondrial membrane potential (MMP). The two-way ANOVA analysis of the results showed that, through antagonistic interaction, pyruvate prevented VOSO₄-induced total ROS generation, which could be observed at the 3 h time point. In addition, through the independent action and antagonistic interaction with VOSO₄, pyruvate provided a pronounced protective effect against VOSO₄-mediated mitochondrial toxicity at 24-h exposure, i.e., prevention of VOSO₄-induced hyperpolarisation and depolarisation of MMP. In conclusion, we found that pyruvate exerted cytoprotective effects against vanadium-induced toxicity at least in part by decreasing ROS generation and preserving mitochondrial functions

Intestinal aging is alleviated by uridine via regulating inflammation and oxidative stress in vivo and in vitro

Many countries in the world are stepping into the aging society with the challenge of the increasing agin gpopulation. The physiological functions of the human body begins to decline with aging, and the intestinal tract as the most important digestive organ will also be aging. How to relieve or reverse aging is an important scientific problem.The aging model in vivo and in vitro was established. Western-blot, indirect immunofluorescence and immunohistochemistry were carried out to explore the anti-aging effect of uridine.In the current study, we examined the anti-aging effect of uridine in vivo and in vitro experiments. In vitro cell model, we found that the aging level of intestinal tract was significantly reduced by uridine, uridine treatment down-regulated the Sa-β-gal-positive cells. Furthermore, the levels of inflammation and oxidative stress were also significantly reduced by uridine treatment. On this basis, in vivo experiments, we found that the aging level of mice fed with uridine was significantly lower than that of the control group as demonstrated by immunohistochemistry and Western blot analyses.In conclusion, our current research indicates that uridine shows a good anti-aging effect,which suggests that uridine is expected to be used as a health food or clinical drug to treat intestinal aging.

NAD+, Senolytics, or Pyruvate for Healthy Aging?

In last decades, healthy aging has become one of research hotspots in life science. It is well known that the nicotinamide adenine dinucleotide oxidized form (NAD⁺) level in cells decreases with aging and aging-related diseases. Several years ago, one of NAD⁺ precursors was first demonstrated with its new role in DNA damage repairing in mice, restoring old mice to their physical state at young ones. The finding encourages extensive studies in animal models and patients. NAD⁺ and its precursors have been popular products in nutrition markets. Alternatively, it was also evidenced that clearance of cellular senescence by senolytics preserved multiorgan (kidney and heart) function and extended healthy lifespan in mice. Subsequent studies confirmed findings in elderly patients subjected with idiopathic pulmonary fibrosis. The senolytic therapy is now focused on various diseases in animal and clinical studies. However, pyruvate, as both a NAD⁺ substitute and a new senolytic, may be advantageous, on the equimolar basis, over current products above in preventing and treating diseases and aging. Pyruvate-enriched fluids, particularly pyruvate oral rehydration salt, may be a novel intervention for diseases and aging besides critical care. Albeit the direct evidence that benefits healthy aging is still limited to date, pyruvate, as both NAD⁺ provider and senolytic agent, warrants intensive research to compare NAD⁺ or senolytics for healthy aging, specifically on the equimolar basis, in effective blood levels. This review briefly discussed the recognition of healthy aging by comparing NAD⁺ and Senolytics with sodium pyruvate from the clinical point of view.