Pyruvate Dehydrogenase Complex Activity Research Articles

Chronic activation of pDCs in autoimmunity is linked to dysregulated ER stress and metabolic responses.

Plasmacytoid dendritic cells (pDCs) chronically produce type I interferon (IFN-I) in autoimmune diseases, including systemic sclerosis (SSc) and systemic lupus erythematosus (SLE). We report that the IRE1α-XBP1 branch of the unfolded protein response (UPR) inhibits IFN-α production by TLR7- or TLR9-activated pDCs. In SSc patients, UPR gene expression was reduced in pDCs, which inversely correlated with IFN-I-stimulated gene expression. CXCL4, a chemokine highly secreted in SSc patients, downregulated IRE1α-XBP1-controlled genes and promoted IFN-α production by pDCs. Mechanistically, IRE1α-XBP1 activation rewired glycolysis to serine biosynthesis by inducing phosphoglycerate dehydrogenase (PHGDH) expression. This process reduced pyruvate access to the tricarboxylic acid (TCA) cycle and blunted mitochondrial ATP generation, which are essential for pDC IFN-I responses. Notably, PHGDH expression was reduced in pDCs from patients with SSc and SLE, and pharmacological blockade of TCA cycle reactions inhibited IFN-I responses in pDCs from these patients. Hence, modulating the IRE1α-XBP1-PHGDH axis may represent a hitherto unexplored strategy for alleviating chronic pDC activation in autoimmune disorders.

1176P Open-label, dose escalation, phase I/II study to assess safety, tolerability, immunogenicity and preliminary clinical activity of the therapeutic cancer vaccine PDC*lung01 with or without anti-programmed death-1 (PD-1) treatment in patients with non-small cell lung cancer (NSCLC)

PDC*lung01 (IMP) is a therapeutic cancer vaccine consisting of an irradiated plasmacytoid dendritic cell line loaded with HLA-A*02:01 restricted peptides (NY-ESO-1, MAGE-A3, MAGE-A4, Multi-MAGE-A, MUC1, Survivin and Melan-A) and able to prime and expand peptide-specific CD8+ T cells in vitro and in vivo, and is synergistic with anti-PD-1.

Efficacy of Lactococcus lactis strain plasma (LC-Plasma) in easing symptoms in patients with mild COVID-19: protocol for an exploratory, multicentre, double-blinded, randomised controlled trial (PLATEAU study)

IntroductionThe COVID-19 pandemic has been a major concern worldwide; however, easily accessible treatment options for patients with mild COVID-19 remain limited. Since the oral intake of Lactococcus lactis strain plasma...

The Role of the Pyruvate Dehydrogenase Complex in the Development of Ischemic-Reperfusion Syndrome

Background. One of the key components of energy metabolism is the pyruvate dehydrogenase complex (PDC), the activity of which can be targeted by some cytoprotectors. However, their role remains unclear. It is known that the activation of the PDC in tumor cells leads to an inversion of anaerobic glycolysis with an increase in the generation of free radicals in the respiratory chain and a decrease in viability. At the same time, there is evidence of increased resistance of normal cells to hypoxia and reperfusion.Objectives. Analysis of current information on the role of PDC in the development of pathologic biochemical changes in ischemic reperfusion syndrome and methods of metabolic correction using agents for regulating the activity of the considered multienzyme complex. Methods. The bibliographical search was carried out across the eLIBRARY and PubMed databases with a selection of articles published over the past 10 years in the English and Russian languages, as well as some parts of fundamental works in the selected field, published more than 10 years. To be selected for bibliographical review, the article can be of any design, reflecting the ideas about the role of PDC in the development of pathologic biochemical changes in ischemic-reperfusion lesions of various organs and tissues.Results. The bibliographical analysis indicates a decrease in the activity of PDC in myocardial tissue during a heart attack or heart failure, the activity of the enzyme in skeletal muscles decreases against the background of acute hypoxia. PDC activity also decreases under chronic stress and extensive muscular exercise. At the same time, the PDC activity remains at the normal level in the ischemic period, and the transition to the reperfusion period is accompanied by a sharp decrease in the activity of the multienzyme complex. The PDC inactivation occurring under these conditions can result from a damage by reactive oxygen species, as well as by regulatory control changes through phosphorylation/dephosphorylation. Assuming the key role of PDC in the development of energy exchange disorders against the ischemic-reperfusion injuries 2 main strategies might be offered for metabolic correction: 1) an increase in the activity of PDC (activator — sodium dichloroacetate) or compensation for its lack with substrates of the tricarboxylic acids (acetylcarnitine, β-ydroxybutyrate); 2) protection of PDC from damage (antioxidants).Conclusion. The basis of energy exchange disorders in the reperfusion period is a decrease in PDC activity, and modification of its activity is a promising direction for metabolic prevention or correction of ischemic-reperfusion injures.

Lactoferrin and its digestive peptides induce interferon-α production and activate plasmacytoid dendritic cells ex vivo

Plasmacytoid dendritic cells (pDCs) recognise viral single-stranded RNA (ssRNA) or CpG DNA via Toll-like receptor (TLR)-7 and TLR9, and produce interferon (IFN)-α. Activated pDCs upregulate human leukocyte antigen (HLA)-DR and CD86 expression levels. Ingestion of bovine lactoferrin (LF) activates pDCs, but little is known about its effects. In this study, the effects of LF and its pepsin hydrolysate (LFH) on the production of IFN-α from peripheral blood mononuclear cells (PBMCs) and pDCs were examined. PBMCs were prepared from peripheral blood of healthy adults and incubated with LF, LFH, or lactoferricin (LFcin) in the absence or presence of ssRNA derived from human immunodeficiency virus. The concentration of IFN-α in the supernatant and the expression levels of IFN-α, HLA-DR, and CD86 in pDCs were quantified by enzyme-linked immunosorbent assay and flow cytometry. In the absence of ssRNA, the concentration of IFN-α was negligible and LF had no effect on it. In the presence of ssRNA, IFN-α was detected at a certain level, and LF and LFH significantly increased its concentration. The increase caused by LFH and LFcin were comparable. In addition, LF significantly upregulated the expression levels of IFN-α, HLA-DR, and CD86 in pDCs. LF and its digestive peptides induced IFN-α production and activated pDCs in the presence of ssRNA, suggesting that LF modulates the immune system by promoting pDC activation upon viral recognition.

Human Plasmacytoid Dendritic Cells Express C-Type Lectin Receptors and Attach and Respond to Aspergillus fumigatus.

Plasmacytoid dendritic cells (pDCs) have been implicated as having a role in antifungal immunity, but mechanisms of their interaction with fungi and the resulting cellular responses are not well understood. In this study, we identify the direct and indirect biological response of human pDCs to the fungal pathogen Aspergillus fumigatus and characterize the expression and regulation of antifungal receptors on the pDC surface. Results indicate pDCs do not phagocytose Aspergillus conidia, but instead bind hyphal surfaces and undergo activation and maturation via the upregulation of costimulatory and maturation markers. Measuring the expression of C-type lectin receptors dectin-1, dectin-2, dectin-3, and mannose receptor on human pDCs revealed intermediate expression of each receptor compared with monocytes. The specific dectin-1 agonist curdlan induced pDC activation and maturation in a cell-intrinsic and cell-extrinsic manner. The indirect activation of pDCs by curdlan was much stronger than direct stimulation and was mediated through cytokine production by other PBMCs. Overall, our data indicate pDCs express various C-type lectin receptors, recognize and respond to Aspergillus hyphal Ag, and serve as immune enhancers or modulators in the overarching fungal immune response.

Plasmacytoid Dendritic Cells, a Novel Target in Myeloid Neoplasms.

Simple SummaryPlasmacytoid dendritic cells are the main type I interferon producing cells in humans and are able to modulate innate and adaptive immune responses. Tumor infiltration by plasmacytoid dendritic cells is already described and is associated with poor outcomes in cancers. In hematological diseases, Blastic Plasmacytoid Dendritic Cells Neoplasm (blastic counterpart) is well described, but little is known about tumor infiltration by mature plasmacytoid dendritic cells described in Myeloid Neoplasms (myeloid tumor cells and clonal pDC proliferation). This review provides a comprehensive overview of plasmacytoid dendritic cells in Myeloid Neoplasms.Plasmacytoid dendritic cells (pDC) are the main type I interferon producing cells in humans and are able to modulate innate and adaptive immune responses. Tumor infiltration by plasmacytoid dendritic cells is already well described and is associated with poor outcomes in cancers due to the tolerogenic activity of pDC. In hematological diseases, Blastic Plasmacytoid Dendritic Cells Neoplasm (BPDCN), aggressive leukemia derived from pDCs, is well described, but little is known about tumor infiltration by mature pDC described in Myeloid Neoplasms (MN). Recently, mature pDC proliferation (MPDCP) has been described as a differential diagnosis of BPDCN associated with acute myeloid leukemia (pDC-AML), myelodysplastic syndrome (pDC-MDS) and chronic myelomonocytic leukemia (pDC-CMML). Tumor cells are myeloid blasts and/or mature myeloid cells from related myeloid disorders and pDC derived from a clonal proliferation. The poor prognosis associated with MPDCP requires a better understanding of pDC biology, MN oncogenesis and immune response. This review provides a comprehensive overview about the biological aspects of pDCs, the description of pDC proliferation in MN, and an insight into putative therapies in pDC-AML regarding personalized medicine.

Overexpression of GsCNGC20-f from Glycine soja confers submergence tolerance to hairy-root composite soybean plants and Arabidopsis seedlings by enhancing anaerobic respiration

Cyclic nucleotide-gated channels (CNGCs) in plants are nonselective Ca 2+ -permeable cationic channel proteins, that are part of the signal transduction cascade system and are involved in the physiological regulation of plant responses to adverse environments. This study firstly showed that the stronger submergence tolerance of G. soja P18B seedlings compared to the G. max cultivar KF1, might be related to the enhanced processes of Ca 2+ signal cascade (higher Ca 2+ content), anaerobic metabolism (higher activities of PDC and ADH), and energy reserves (higher ATP level) in the leaves during submergence. Then, the potential submergence-responsive differentially expressed genes (DEGs) enriched in voltage-gated potassium channel activity, such as GsCNGC20-f and GsCNGC20-g , and those enriched in calcium ion binding, i.e. GsCaML, GsCAM4, GsCML41, and GsCML45 were identified through leaf transcriptomic analysis of P18B and KF1 under submergence. The qRT-PCR, tobacco leaf transient expression and GUS staining displayed a more obviously induced upregulation of GsCNGC20-f and GsCNGC20-g by submergence stress. BiFC and Y2H assays showed that plasma membrane-located GsCNGC-f could interact with GsCaM4 or GsCaML. Finally, overexpression of GsCNGC20-f could alleviate submergence injury in hairy-root composite soybean plants or transgenic Arabidopsis seedlings by maintaining a higher content of Ca 2+ and activities of PDC and ADH (associated with upregulated gene expression of PDCs and ADHs ), and thereafter enhancing ATP levels in the leaves via improved anaerobic respiration under hypoxic conditions. The functions of GsCNGC20-f involving in the adaptation and survival of G. soja P18B seedlings under submergence stress can provide new perspectives for the molecular breeding of flooding-tolerant soybeans or other crops. • Two potential CNGC genes, GsCNGC20-f and GsCNGC20-g, were identified from the submergence-tolerant G. soja accession (P18B). • The plasma membrane-located GsCNGC-f could interact with GsCaM4 or GsCaML. • GsCNGC20-f could alleviate submergence stress on transgenic soybean or Arabidopsis plants by enhancing anaerobic respiration.

Celastrol alleviates high-fat diet-induced obesity via enhanced muscle glucose utilization and mitochondrial oxidative metabolism-mediated upregulation of pyruvate dehydrogenase complex

Celastrol, a natural triterpene from the Tripterygium wilfordii has been demonstrated to possess attributive properties to attenuate various animal models of obesity-associated conditions. The present study aimed to elucidate the putative targets of celastrol on intracellular glucose utilization and mitochondrial oxidative metabolism in the isolated quadriceps skeletal muscle of high-fat diet (HFD)-induced obese male C57BL6/J mice. Here we showed that celastrol remarkably attenuated obesity and insulin resistance through improvement of systemic glucose tolerance and insulin sensitivity. Enhanced mRNA transcription factors of key rate-limiting glycolytic and TCA cycle enzymes were observed following celastrol administration. The metabolic profiling revealed profound changes induced by celastrol administration on several key metabolites of glycolysis and tricarboxylic acid (TCA) cycle including glucose-1-phosphate, pyruvate, citrate, α-ketoglutarate, succinate and fumarate. Celastrol effectively increased mitochondrial oxidative functions via increased pyruvate dehydrogenase complex (PDC) activity and downregulated pyruvate dehydrogenase kinase 4 (PDK4) expressions. Enhanced succinate dehydrogenase (SDH) activity was noticed following celastrol co-supplementation, leading to a steady establishment of the electrochemical gradient across mitochondrial membrane for ATP production and mitochondrial biogenesis. In conclusion, the current findings accentuate the therapeutic potential of celastrol against HFD-induced obese mice via enhanced glucose utilization and mitochondrial oxidative metabolism-mediated upregulation of PDC activity in the skeletal muscle.

The Pyruvate Dehydrogenase Complex Mitigates LPS-Induced Endothelial Barrier Dysfunction by Metabolic Regulation.

Sepsis is a fatal health issue induced by an aberrant host response to infection, and it correlates with organ damage and a high mortality rate. Endothelial barrier dysfunction and subsequent capillary leakage play major roles in sepsis-induced multiorgan dysfunction. Anaerobic glycolysis is the primary metabolic mode in sepsis and the pyruvate dehydrogenase complex (PDHC) serves as a critical hub in energy regulation. Therefore, it is important to understand the role of PDHC in metabolic regulation during the development of sepsis-induced endothelial barrier dysfunction.In present study, human umbilical vein endothelial cells (HUVECs) and C57 BL/6 mice were treated with lipopolysaccharide (LPS) as models of endotoxemia. LPS increased basal glycolysis, compensatory glycolysis, and lactate secretion, indicating increased glycolysis level in endothelial cells (ECs). Activation of PDHC with dichloroacetate (DCA) reversed LPS-induced glycolysis, allowing PDHC to remain in the active dephosphorylated state, thereby preventing lactic acid production and HUVECs monolayers barrier dysfunction, as assessed by transendothelial electrical resistance and Fluorescein Isothiocyanate-labeled dextran. The in vivo study also showed that the lactate level and vascular permeability were increased in LPS-treated mice, but pretreatment with DCA attenuated these increases. The LPS-treated HUVEC model showed that DCA reversed LPS-induced phosphorylation of pyruvate dehydrogenase E1α Ser293 and Ser300 to restore PDHC activity. Immunoprecipitation results showed that LPS treatment increased the acetylation level of PDH E1α in HUVECs.Our study suggested that activation of PDHC may represent a therapeutic target for treatment of LPS-induced endothelial barrier dysfunction.

Low Density Lipoprotein Exposure of Plasmacytoid Dendritic Cells Blunts Toll-like Receptor 7/9 Signaling via NUR77.

Background: Pathogens or trauma-derived danger signals induced maturation and activation of plasmacytoid dendritic cells (pDCs) is a pivotal step in pDC-dependent host defense. Exposure of pDC to cardiometabolic disease-associated lipids and proteins may well influence critical signaling pathways, thereby compromising immune responses against endogenous, bacterial and viral pathogens. In this study, we have addressed if hyperlipidemia impacts human pDC activation, cytokine response and capacity to prime CD4+ T cells. METHODS AND RESULTS: We show that exposure to pro-atherogenic oxidized low-density lipoproteins (oxLDL) led to pDC lipid accumulation, which in turn ablated a Toll-like receptor (TLR) 7 and 9 dependent up-regulation of pDC maturation markers CD40, CD83, CD86 and HLA-DR. Moreover, oxLDL dampened TLR9 activation induced the production of pro-inflammatory cytokines in a NUR77/IRF7 dependent manner and impaired the capacity of pDCs to prime and polarize CD4+ T helper (Th) cells. CONCLUSION: Our findings reveal profound effects of dyslipidemia on pDC responses to pathogen-derived signals.

Insulin reduces pyroptosis-induced inflammation by PDHA1 dephosphorylation-mediated NLRP3 activation during myocardial ischemia-reperfusion injury.

Previous studies proved that pyrin domain-containing protein 3 (NLRP3)-induced pyroptosis plays an important role in Myocardial ischemia-reperfusion injury (MIRI). Insulin can inhibit the activation of NLRP3 inflammasome, although the exact mechanism remains unclear. The aim of this study was to determine whether insulin reduces NLRP3-induced pyroptosis by regulating pyruvate dehydrogenase E1alpha subunit (PDHA1) dephosphorylation during MIRI. Rat hearts were subject to 30 min global ischemia followed by 60 min reperfusion, with or without 0.5 IU/L insulin. Myocardial ischemia-reperfusion injury was evaluated by measuring myocardial enzymes release, Cardiac hemodynamics, pathological changes, infarct size, and apoptosis rate. Cardiac aerobic glycolysis was evaluated by measuring ATP, lactic acid content, and pyruvate dehydrogenase complex (PDHc) activity in myocardial tissue. Recombinant adenoviral vectors for PDHA1 knockdown were constructed. Pyroptosis-related proteins were measured by Western blotting analysis, immunohistochemistry staining, and ELISA assay, respectively. It was found that insulin significantly reduced the area of myocardial infarction, apoptosis rate, and improved cardiac hemodynamics, pathological changes, energy metabolism. Insulin inhibits pyroptosis-induced inflammation during MIRI. Subsequently, Adeno-associated virus was used to knock down cardiac PDHA1 expression. Knockdown PDHA1 not only promoted the expression of NLRP3 but also blocked the inhibitory effect of insulin on NLRP3-mediated pyroptosis in MIRI. Results suggest that insulin protects against MIRI by regulating PDHA1 dephosphorylation, its mechanism is not only to improve myocardial energy metabolism but also to reduce the NLRP3-induced pyroptosis.

Cellular and molecular mediators of thymic DC homeostasis and activation

Abstract Central tolerance in the thymus ensures that autoreactive thymocytes undergo negative selection or diversion to the regulatory T cell (Treg) lineage. Thymic antigen presenting cells (APCs) such as medullary thymic epithelial cells (mTECs) and dendritic cells (DCs) present myriad self-peptides to thymocytes to induce central tolerance. We and others have previously shown that thymic cDCs can be subdivided into activated CCR7+MHC-IIhi and resting CCR7− MHC-IIlo cDC1 and cDC2 subsets with distinct functional properties, suggesting the thymic DC compartment may be more heterogeneous than previously described. Here, we performed single-cell RNA sequencing (scRNAseq) of hematopoietic APCs isolated from adult mouse thymi to comprehensively identify thymic DC subsets with distinct gene expression profiles. Our data reveal 11 transcriptionally distinct cDC subsets. We identify 6 cDC1 subsets, 3 cDC2 subsets, 2 activated CCR7+ “cDC3” subsets distinguished by expression of cDC1 and cDC2 markers, and 4 plasmacytoid DC clusters. Through functional assays, we find that the XCR1+ cDC3s are the most efficient at presenting mTEC-derived peptides on MHC-I and MHC-II, while 2 distinct cDC2 subsets are the most efficient at generating Tregs in vitro. Additional scRNA-seq and flow cytometry analyses of thymic DCs from mice in which thymocyte maturation was blocked at different developmental stages reveal candidate cellular and molecular crosstalk signals that regulate homeostasis and/or activation of pDC and cDC subsets. Our findings reveal hitherto unknown functional heterogeneity within the thymic DC compartment and identify potential interactions that support DC homeostasis and activation which in turn could impact central tolerance. Supported by NIH P01 AI139449-02

Levels of epigenetic regulators TET2 and DNMT1 correlate with virus-stimulated pDC differentiation from IFN-α producing cells to antigen presenting cells

Abstract Plasmacytoid dendritic cells (pDC) are potent producers of IFN-α in response to DNA and RNA viruses and subsequently mature into antigen presenting cells. We investigated the role of DNA methyltransferase 1 (DNMT1) and Ten-eleven translocation methyl-cytosine dioxygenase 2 (TET2), which are generally known as gene silencers and activators, respectively, in pDC activation. PBMC from healthy donors were stimulated with Herpes Simplex Virus (HSV) or Influenza-A virus (IAV) for 6- and 24h. PBMC were surface-stained for pDC markers CD123, HLA-DR and CD11C and co-stimulatory markers CD80 and CD86, then intracellularly for DNMT1, TET2 and IFN-α, and acquired by flow cytometry. mRNA expression of DNMT1 in purified pDC was determined by qRT-PCR. At 6h, DNMT1 protein was expressed at equivalent levels in pDC with and without stimulation and in IFN-α+ and IFN-α-pDC, and in unstimulated controls. In contrast, TET2 proteins were elevated in IFN-α+ but not IFN-α-pDC and controls at 6h. At 24h, DNMT1 increased while TET2 was reduced in stimulated pDC, correlating with high IFN-α levels at 6h and low levels at 24h. There was no change in DNMT1 gene expression in virus-stimulated vs. unstimulated controls. CD80 and CD86 were elevated at 24h compared to 6h in stimulated pDC, confirming pDC differentiation from IFN-α producing to antigen presenting cells. At the point of pDC differentiation, TET2 levels were decreased and DNMT1 increased. These results suggest that TET2 is demethylating and causing activation of genes associated with pDC IFN-α production, while DNMT1 methylates and silences genes in this pathway. This results in an initial induction of TET2 and IFN-α production followed by upregulation of co-stimulatory markers, DNMT1 and loss of IFN-α. Supported by 1. AAI trainee fellowship Careers in Immunology Fellowship Program AAI EIN #: 52-2317193 2. R01Al106125

Porcine Plasmacytoid Dendritic Cells Are Unique in Their Expression of a Functional NKp46 Receptor.

The activating receptor NKp46 shows a unique expression pattern on porcine leukocytes. We showed already that in swine not all NK cells express NKp46 and that CD3+NKp46+ lymphocytes form a T-cell subset with unique functional properties. Here we demonstrate the expression of NKp46 on CD4highCD14-CD172a+ porcine plasmacytoid dendritic cells (pDCs). Multicolor flow cytometry analyses revealed that the vast majority of porcine pDCs (94.2% ± 4) express NKp46 ex vivo and have an increased expression on the single-cell level compared to NK cells. FSC/SSChighCD4highNKp46+ cells produced high levels of IFN-α after CpG ODN 2216 stimulation, a hallmark of pDC function. Following receptor triggering with plate-bound monoclonal antibodies against NKp46, phosphorylation of signaling molecules downstream of NKp46 was analyzed in pDCs and NK cells. Comparable to NK cells, NKp46 triggering led to an upregulation of the phosphorylated ribosomal protein S6 (pS6) in pDCs, indicating an active signaling pathway of NKp46 in porcine pDCs. Nevertheless, a defined effector function of the NK-associated receptor on porcine pDCs could not be demonstrated yet. NKp46-mediated cytotoxicity, as shown for NK cells, does not seem to occur, as NKp46+ pDCs did not express perforin. Yet, NKp46 triggering seems to contribute to cytokine production in porcine pDCs, as induction of TNF-α was observed in a small pDC subset after NKp46 cross-linking. To our knowledge, this is the first report on NKp46 expression on pDCs in a mammalian species, showing that this receptor contributes to pDC activation and function.

PDK4 Inhibition Ameliorates Melatonin Therapy by Modulating Cerebral Metabolism and Remyelination in an EAE Demyelinating Mouse Model of Multiple Sclerosis.

We recently showed that melatonin ameliorates the severity of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. However, efficiency of melatonin therapy was associated with side effects, manifested by slowing down of remyelination, through increasing the inhibitory effects of brain pyruvate dehydrogenase kinase-4 (PDK-4) on pyruvate dehydrogenase complex (PDC), a key enzyme in fatty acid (FA) synthesis during remyelination. In this study, we investigated the metabolic profile of FA synthesis using combination therapy of melatonin and diisopropylamine dichloroacetate (DADA), a PDK4 inhibitor, in EAE mice. Disease progression was monitored by recording the disability scores. Immunological, oligodendrogenesis and metabolic factors were also evaluated. Results showed that combination therapy of melatonin and DADA significantly reduced EAE disability scores, compared to melatonin, whereas DADA alone did not have any effect. In addition, co-therapy inhibited pro-inflammatory while increasing anti-inflammatory cytokines, significantly better than melatonin alone. Moreover, administration of combination drugs recovered the declined expression of oligodendrocytic markers in EAE, more potently than melatonin. Furthermore, co-therapy affected cerebral energy metabolism by significantly reducing lactate levels while increasing N-acetylaspartate (NAA) and 3-hydroxy-3-methyl-glutaryl-coenzyme-A reductase (HMGCR) levels. Finally, while melatonin increased lactate and PDK4 expression levels and greatly reduced PDC activity, co-therapy significantly restored PDC function while reducing the lactate levels. In summary, administration of melatonin with DADA increased the efficiency of melatonin treatment by eliminating the inhibitory effects of PDK4 on PDC’s function, a critical step for proper FA synthesis during remyelination.

Melatonin could be used for Treatment of COVID-19?

Coronaviruses (CoVs) are a broad family of potentially serious RNA viruses that are now causing an outbreak of respiratory disease known as CoV disease 2019 (COVID-19). Melatonin is a pineal hormone that is predominantly produced and released at night from the amino acid tryptophan. Melatonin and its metabolites are also important in immunomodulation, and they have antioxidative properties due to their capacity to scavenge reactive oxygen species both directly and indirectly. COVID-19 leads to changes of altered consciousness levels in about 15% of hospitalized patients, starting from somnolence to disorientation, delirium, stupor, and coma. Melatonin can decrease the molecules that cause delirium in the elderly and central respiratory depression, such as benzodiazepines and antipsychotics. Melatonin may help alleviate infection-induced acute respiratory distress as well as its diverse effects, which include anti-inflammatory, antioxidative, and immune-enhancing properties. Its supplemental dose may be able to prevent SARS-COV-2 infections by reversing aerobic glycolysis via suppression of both HIF-1 and mTOR, allowing pyruvate dehydrogenase complex activity to be suppressed and acetyl-coenzyme A to be produced. When mitochondrion-produced and parenteral melatonin are combined, the cytokine storm is reduced, and COVID-19 infection-induced damage is alleviated. In conclusion, melatonin could have an important role in the management of COVID-19.

PYRUVATE DEHYDROGENASE COMPLEX ACTIVITY IN THE RAT`S KIDNEYS UNDER CONDITIONS OF TOXIC ACETAMINOPHEN DAMAGE WITH PROTEIN DEFICIENCY

The aim of this work was to study the research the enzymatic activity of pyruvate dehydrogenase complex and lac-tate dehydrogenase and determination of the lactate/pyruvate ratio in rat kidneys under conditions of toxic damage by acetaminophen against the background of protein deficiency.The activity of the pyruvate dehydrogenase complex activity was determined according to a method based on the reaction of oxidative decarboxylation of pyruvate with simultaneous reduction of NAD+, which is measured spectrophotometrically at 340 nm. LDH activity was studied by an optimized optical method, which is based on the reaction of conversion of pyruvate to lactate with concomitant oxidation of NADH, which was measured using a spectrophotometer at λ = 340 nm. Lactate content was measured spectrophotometrically by the ability of FeCl3 to interact with lactate ions, resulting in the formation of a bright yellow iron lactate solution, which is recorded at a wavelength of 390 nm. The concentration of pyruvate was deter-mined by the modified Umbright method, which is based on the reaction of the interaction of pyruvate with 2,4-Dinitrophenylhydrazine (2,4-DNPH) in an alkaline medium, during which hydrazine is formed, which was recorded using a photoelectrocolorimeter at λ = 440 nm. The study was conducted on 4 groups of experimental animals: I - control animals (K); II – rats kept on a low-protein diet (LPD); ІІІ – animals in which acute toxic damage was caused by acetaminophen (TI); IV – rats on a low-protein diet, simulated acute toxic damage with acetaminophen (LPD/TI). It is demonstrated that under the conditions of dietary protein deficiency in the kidneys, there is a decrease in the activi-ty of the pyruvate dehydrogenase complex while maintaining the control indicators of the lactate/pyruvate ratio and lactate dehydrogenase activity. However, under the conditions of the toxic effect of acetaminophen against the back-ground of dietary protein deficiency in the kidneys, an intensification of the anaerobic pathway of energy supply is observed, as evidenced by a significant decrease in the activity of the pyruvate dehydrogenase complex, an increase in the lactate/pyruvate ratio against the background of lactate dehydrogenase activation. The obtained results can be used to justify approaches to correct energy deficit in animals under the conditions of acetaminophen overdose against the background of protein deficiency.

Glucose metabolism in amyotrophic lateral sclerosis: it is bitter-sweet.

Glucose metabolism in amyotrophic lateral sclerosis: it is bitter-sweet.

Phosphorylation status of pyruvate dehydrogenase in the mousebird Colius striatus undergoing torpor.

Torpor is a heterothermic response that occurs in some animals to reduce metabolic expenditure. The speckled mousebird (Colius striatus) belongs to one of the few avian taxa possessing the capacity for pronounced torpor, entering a hypometabolic state with concomitant decreases in body temperature in response to reduced food access or elevated thermoregulatory energy requirements. The pyruvate dehydrogenase complex (PDC) is a crucial site regulating metabolism by bridging glycolysis and the Krebs cycle. Three highly conserved phosphorylation sites are found within the E1 enzyme of the complex that inhibit PDC activity and reduce the flow of carbohydrate substrates into the mitochondria. The current study demonstrates a marked increase in S232 phosphorylation during torpor in liver, heart, and skeletal muscle of C. striatus. The increase in S232 phosphorylation during torpor was particularly notable in skeletal muscle where levels were ~49-fold higher in torpid birds compared to controls. This was in contrast to the other two phosphorylation sites (S293 and S300) which remained consistently phosphorylated regardless of tissue. The relevant PDH kinase (PDHK1) known to phosphorylate S232 was found to be substantially upregulated (~5-fold change) in the muscle during torpor as well as increasing moderately in the liver (~2.2-fold increase). Additionally, in the heart, a slight (~23%) decrease in total PDH levels was noted. Taken together the phosphorylation changes in PDH suggest that inhibition of the complex is a common feature across several tissues in the mousebird during torpor and that this regulation is mediated at a specific residue.