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Numerous reports of vascular events after an initial recovery from COVID-19 form our impetus to investigate the impact of COVID-19 on vascular health of recovered patients. We found elevated levels of circulating endothelial cells (CECs), a biomarker of vascular injury, in COVID-19 convalescents compared to healthy controls. In particular, those with pre-existing conditions (e.g., hypertension, diabetes) had more pronounced endothelial activation hallmarks than non-COVID-19 patients with matched cardiovascular risk. Several proinflammatory and activated T lymphocyte-associated cytokines sustained from acute infection to recovery phase, which correlated positively with CEC measures, implicating cytokine-driven endothelial dysfunction. Notably, we found higher frequency of effector T cells in our COVID-19 convalescents compared to healthy controls. The activation markers detected on CECs mapped to counter receptors found primarily on cytotoxic CD8 + T cells, raising the possibility of cytotoxic effector cells targeting activated endothelial cells. Clinical trials in preventive therapy for post-COVID-19 vascular complications may be needed.

How severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections engage cellular host pathways and innate immunity in infected cells remains largely elusive. We performed an integrative proteo-transcriptomics analysis in SARS-CoV-2 infected Huh7 cells to map the cellular response to the invading virus over time. We identified four pathways, ErbB, HIF-1, mTOR and TNF signaling, among others that were markedly modulated during the course of the SARS-CoV-2 infection in vitro. Western blot validation of the downstream effector molecules of these pathways revealed a dose-dependent activation of Akt, mTOR, S6K1 and 4E-BP1 at 24 hours post infection (hpi). However, we found a significant inhibition of HIF-1α through 24hpi and 48hpi of the infection, suggesting a crosstalk between the SARS-CoV-2 and the Akt/mTOR/HIF-1 signaling pathways. Inhibition of the mTOR signaling pathway using Akt inhibitor MK-2206 showed a significant reduction in virus production. Further investigations are required to better understand the molecular sequelae in order to guide potential therapy in the management of severe coronavirus disease 2019 (COVID-19) patients.

Background Glutamate oxaloacetate transaminase 1 (GOT1) regulates cellular metabolism through coordinating the utilization of carbohydrates and amino acids to meet nutrient requirements. KRAS mutated cancer cells were recently shown to rely on GOT1 to support long-term cell proliferation. The aim of the present study was to address the role of GOT1 in the metabolic adaption of cancer cells. Methods GOT1-null and knockdown cell lines were established through CRISPR/Cas9 and shRNA techniques. The growth properties, colony formation ability, autophagy and selected gene expression profiles were analysed. Glucose deprivation decreased the viability of the GOT1-null cells and rescue experiments were conducted with selected intermediates. The redox NADH/NAD + homeostasis as well as lactate secretion were determined. GOT1 expression levels and correlation with survival rates were analysed in selected tumor databases. Results Inhibition of GOT1 sensitized the cancer cells to glucose deprivation, which was partially counteracted by oxaloacetate and phosphoenol pyruvate, metabolic intermediates downstream of GOT1. Moreover, GOT1-null cells accumulated NADH and displayed a decreased ratio of NADH/NAD + with nutrient depletion. The relevance of GOT1 as a potential target in cancer therapy was supported by a lung adenocarcinoma RNA-seq data set as well as the GEO:GSE database of metastatic melanoma where GOT1 expression was increased. High levels of GOT1 were further linked to poor survival as analysed by the GEPIA web tool, in thyroid and breast carcinoma and in lung adenocarcinoma. Conclusions Our study suggests an important role of GOT1 to coordinate the glycolytic and the oxidative phosphorylation pathways in KRAS mutated cancer cells. GOT1 is crucial to provide oxaloacetate at low glucose levels, likely to maintain the redox homeostasis. Our data suggest GOT1 as a possible target in cancer therapy.

Genome-scale metabolic models (GSMMs) can provide novel insights into metabolic reprogramming during disease progression and therapeutic interventions. We developed a context-specific system-level GSMM of people living with HIV (PLWH) using global RNA sequencing data from PBMCs with suppressive viremia either by natural (elite controllers, PLWH EC ) or drug-induced (PLWH ART ) control. This GSMM was compared with HIV-negative controls (HC) to provide a comprehensive systems-level metabo-transcriptomic characterization. Transcriptomic analysis identified up-regulation of oxidative phosphorylation as a characteristic of PLWH ART , differentiating them from PLWH EC with dysregulated complexes I, III, and IV. The flux balance analysis identified altered flux in several intermediates of glycolysis including pyruvate, α-ketoglutarate, and glutamate, among others, in PLWH ART . The in vitro pharmacological inhibition of OXPHOS complexes in a latent lymphocytic cell model (J-Lat 10.6) suggested a role for complex IV in latency reversal and immunosenescence. Furthermore, inhibition of complexes I/III/IV induced apoptosis, collectively indicating their contribution to reservoir dynamics.

HIV-1 infection induces a chronic inflammatory environment not restored by suppressive antiretroviral therapy (ART). As of today, the effect of viral suppression and immune reconstitution in people living with HIV-1 (PLWH) has been well described but not completely understood. Herein, we show how PLWH who naturally control the virus (PLWH EC ) have a reduced proportion of CD4 + CCR6 + and CD8 + CCR6 + cells compared to PLWH on suppressive ART (PLWH ART ) and HIV-1 negative controls (HC). Expression of CCR2 was reduced on both CD4 + , CD8 + and classical monocytes in PLWH EC compared to PLWH ART and HC. Longer suppressive therapy, measured in the same patients, decreased number of cells expressing CCR2 on all monocytic cell populations while expression on CD8 + T cells increased. Furthermore, the CD4 + CCR6 + /CCR6 − cells exhibited a unique proteomic profile with a modulated energy metabolism in PLWH EC compared to PLWH ART independent of CCR6 status. The CD4 + CCR6 + cells also showed an enrichment in proteins involved in apoptosis and p53 signalling in PLWH EC compared to PLWH ART , indicative of increased sensitivity towards cell death mechanisms. Collectively, this data shows how PLWH EC have a unique chemokine receptor profile that may aid in facilitating natural control of HIV-1 infection. The expression profiles dynamics of several chemokine receptors are lower for people living with HIV-1 who naturally control the virus compared to those on suppressive antiretroviral therapy and HIV-negative controls, shedding light on the mechanisms of natural control of HIV-1 infection.

Despite successful combination antiretroviral therapy (cART), persistent low-grade immune activation together with inflammation and toxic antiretroviral drugs can lead to long-lasting metabolic flexibility and adaptation in people living with HIV (PLWH). Our study investigated alterations in the plasma metabolic profiles by comparing PLWH on long-term cART(>5 years) and matched HIV-negative controls (HC) in two cohorts from low- and middle-income countries (LMIC), Cameroon, and India, respectively, to understand the system-level dysregulation in HIV-infection. Using untargeted and targeted LC-MS/MS-based metabolic profiling and applying advanced system biology methods, an altered amino acid metabolism, more specifically to glutaminolysis in PLWH than HC were reported. A significantly lower level of neurosteroids was observed in both cohorts and could potentiate neurological impairments in PLWH. Further, modulation of cellular glutaminolysis promoted increased cell death and latency reversal in pre-monocytic HIV-1 latent cell model U1, which may be essential for the clearance of the inducible reservoir in HIV-integrated cells. Mikaeloff et al. use untargeted and targeted LC-MS/MS-based plasma metabolic profiling to discover dysregulated metabolism including that of glutaminolysis in individuals living with HIV. Furthermore, decreased levels of neurosteroids were detected suggesting a potential connection between HIV and neurological impairment.

The mitochondria are essential for cellular energy production and are involved in many processes in the cells. The mitochondria contain their own DNA (mtDNA) that is vital for oxidative phosphorylation since it encodes enzymes of the respiratory chain. Mutations in the mtDNA and alterations in the mtDNA copy number are attributed to various human disorders including cancer. Mitochondrial DNA depletion syndromes (MDS) are a heterogeneous group of disorders characterized by severe depletion of the mtDNA. MDS predominantly manifests in high energy demanding tissues such as the skeletal muscle, brain and liver. Mutations in the genes that are responsible for providing precursors for the mtDNA synthesis such as thymidine kinase 2 (TK2) and deoxyguanosine kinase (dGK) are known to cause MDS.In an attempt to rescue the mtDNA depletion caused by thymidine kinase 2 (Tk2) deficiency in mice, the deoxyribonucleoside kinase from Drosophila melanogaster (Dm-dNK) was expressed in the Tk2 deficient mice (Dm-dNK+/-Tk2-/- ). The Dm-dNK+/- expression was able to rescue the Tk2-/- mice and prolong their life span from 3 weeks to up to 20 months. The Dm-dNK expression driven by the CMV promoter was observed in all tissues with highest expression in skeletal muscle and lower expression in heart, liver and adipose tissues. Dm-dNK+/-Tk2-/- mice maintained normal mtDNA levels in the skeletal muscle and liver throughout the observation time of 20 months. The Dm-dNK expression resulted in highly elevated dNTP pools with dTTP pools being >100 times higher than in the wild type mice. However, the large increase in the dTTP pool did not cause mutations in the nuclear or the mitochondrial DNA. A significant reduction in total body fat (both subcutaneous and visceral fat) was observed only in the Dm-dNK+/-Tk2-/- mice compared to wild type mice, which indicates an altered fat metabolism in these mice mediated through residual Tk2 deficiency.To elucidate effective treatment strategies for TK2 deficiency, a novel mouse model with liver specific expression of Dm-dNK driven by the albumin promoter was generated. Two founder mice with high Dm-dNK expression and activity in the liver was selected for further characterization. These mice will be used to study whether Dm-dNK expression in a single tissue would be able to rescue the sever phenotype caused by Tk2 deficiency in mice.The mitochondrial dicarboxylate carrier, SLC25A10, is involved in the transport of dicarboxylates such as malate and succinate across the mitochondrial inner membrane. To understand the role of the SLC25A10 carrier in regulating cancer cell growth, metabolism and transformation, a knockdown of SLC25A10 in a lung adenocarcinoma cell line (A549) was established and characterized. The growth properties of SLC25A10 knockdown cells changed to a less malignant phenotype, with increased dependency on glutamine and altered NADPH production. An increase in expression of glutamate dehydrogenase and decrease in expression of lactate dehydrogenase indicated a metabolic shift from glycolysis to oxidative phosphorylation in the SLC25A10 knockdown cells. The study demonstrates the importance of SLC25A10 in and regulation of redox homeostasis.