Strain specific differences in vitamin D3 response: impact on gut homeostasis.

Vitamin D3 regulates a variety of biological processes irrespective of its well-known importance for calcium metabolism. Epidemiological and animal studies indicate a role in immune regulation, intestinal barrier function and microbiome diversity. Here, we analyzed the impact of different vitamin D3- containing diets on C57BL/6 and BALB/c mice, with a particular focus on gut homeostasis and also investigated effects on immune cells in vitro. Weak regulatory effects were detected on murine T cells. By trend, the active vitamin D3 metabolite 1,25-dihydroxyvitamin D3 suppressed IFN, GM-CSF and IL-10 cytokine secretion in T cells of C57BL/6 but not BALB/c mice, respectively. Using different vitamin D3-fortified diets, we found a tissue-specific enrichment of mainly CD11b+ myeloid cells but not T cells in both mouse strains e.g. in spleen and Peyer's Patches. Mucin Reg3γ and Batf expression, as well as important proteins for gut homeostasis, were significantly suppressed in the small intestine of C57BL76 but not BALB/c mice fed with a high-vitamin D3 containing diet. Differences between both mouse stains were not completely explained by differences in vitamin D3 receptor expression which was strongly expressed in epithelial cells of both strains. Finally, we analyzed gut microbiome and again an impact of vitamin D3 was detected in C57BL76 but not BALB/c. Our data suggest strain-specific differences in vitamin D3 responsiveness under steady state conditions which may have important implications when choosing a murine disease model to study vitamin D3 effects.

D-2-hydroxyglutarate supports a tolerogenic phenotype with lowered major histocompatibility class II expression in non-malignant dendritic cells and acute myeloid leukemia cells.

D-2-hydroxyglutarate (D-2-HG) accumulates in primary acute myeloid leukemia (AML) patients with mutated isocitrate dehydrogenase (IDH) and other malignancies. D-2-HG suppresses antitumor T cell immunity but little is known about potential effects on non-malignant myeloid cells. Here we show that D-2-HG impairs human but not murine dendritic cell (DC) differentiation, resulting in a tolerogenic phenotype with low major histocompatibility (MHC) class II expression. In line, IDH-mutated AML blasts exhibited lower expression of HLA-DP and were less susceptible to lysis by HLA-DP-specific T cells. Interestingly, D-2-HG reprogrammed metabolism towards increased lactate production in DCs and AML besides its expected impact on DNA demethylation. Vitamin C accelerated DNA demethylation, but only the combination of vitamin C and glycolytic inhibition lowered lactate levels and supported MHC class II expression. Our results indicate an unexpected link between the immunosuppressive metabolites 2-HG and lactic acid and suggest a potentially novel therapeutic strategy with combinations of anti-glycolytic drugs and epigenetic modulators (hypomethylating agents) or other therapeutics for the treatment of AML.

Targeting the microenvironment in the treatment of arteriovenous malformations.

Extracranial arteriovenous malformations (AVMs) are regarded as rare diseases and are prone to complications such as pain, bleeding, relentless growth, and high volume of shunted blood. Due to the high vascular pressure endothelial cells of AVMs are exposed to mechanical stress. To control symptoms and lesion growth pharmacological treatment strategies are urgently needed in addition to surgery and interventional radiology. AVM cells were isolated from three patients and exposed to cyclic mechanical stretching for 24 h. Thalidomide and bevacizumab, both VEGF inhibitors, were tested for their ability to prevent the formation of circular networks and proliferation of CD31+ endothelial AVM cells. Furthermore, the effect of thalidomide and bevacizumab on stretched endothelial AVM cells was evaluated. In response to mechanical stress, VEGF gene and protein expression increased in patient AVM endothelial cells. Thalidomide and bevacizumab reduced endothelial AVM cell proliferation. Bevacizumab inhibited circular network formation of endothelial AVM cells and lowered VEGF gene and protein expression, even though the cells were exposed to mechanical stress. With promising in vitro results, bevacizumab was used to treat three patients with unresectable AVMs or to prevent regrowth after incomplete resection. Bevacizumab controlled bleeding, pulsation, and pain over the follow up of eight months with no patient-reported side effects. Overall, mechanical stress increases VEGF expression in the microenvironment of AVM cells. The monoclonal VEGF antibody bevacizumab alleviates this effect, prevents circular network formation and proliferation of AVM endothelial cells in vitro. The clinical application of bevacizumab in AVM treatment demonstrates effective symptom control with no side effects.

MCT4 blockade increases the efficacy of immune checkpoint blockade.

BACKGROUND & AIMS: Intratumoral lactate accumulation and acidosis impair T-cell function and antitumor immunity. Interestingly, expression of the lactate transporter monocarboxylate transporter (MCT) 4, but not MCT1, turned out to be prognostic for the survival of patients with rectal cancer, indicating that single MCT4 blockade might be a promising strategy to overcome glycolysis-related therapy resistance. METHODS: To determine whether blockade of MCT4 alone is sufficient to improve the efficacy of immune checkpoint blockade (ICB) therapy, we examined the effects of the selective MCT1 inhibitor AZD3965 and a novel MCT4 inhibitor in a colorectal carcinoma (CRC) tumor spheroid model co-cultured with blood leukocytes in vitro and the MC38 murine CRC model in vivo in combination with an antibody against programmed cell death ligand-1(PD-L1). RESULTS: Inhibition of MCT4 was sufficient to reduce lactate efflux in three-dimensional (3D) CRC spheroids but not in two-dimensional cell-cultures. Co-administration of the MCT4 inhibitor and ICB augmented immune cell infiltration, T-cell function and decreased CRC spheroid viability in a 3D co-culture model of human CRC spheroids with blood leukocytes. Accordingly, combination of MCT4 and ICB increased intratumoral pH, improved leukocyte infiltration and T-cell activation, delayed tumor growth, and prolonged survival in vivo. MCT1 inhibition exerted no further beneficial impact. CONCLUSIONS: These findings demonstrate that single MCT4 inhibition represents a novel therapeutic approach to reverse lactic-acid driven immunosuppression and might be suitable to improve ICB efficacy.

Can Exercise Enhance the Efficacy of Checkpoint Inhibition by Modulating Anti-Tumor Immunity?

Immune checkpoint inhibition (ICI) has revolutionized cancer therapy. However, response to ICI is often limited to selected subsets of patients or not durable. Tumors that are non-responsive to checkpoint inhibition are characterized by low anti-tumoral immune cell infiltration and a highly immunosuppressive tumor microenvironment. Exercise is known to promote immune cell circulation and improve immunosurveillance. Results of recent studies indicate that physical activity can induce mobilization and redistribution of immune cells towards the tumor microenvironment (TME) and therefore enhance anti-tumor immunity. This suggests a favorable impact of exercise on the efficacy of ICI. Our review delivers insight into possible molecular mechanisms of the crosstalk between muscle, tumor, and immune cells. It summarizes current data on exercise-induced effects on anti-tumor immunity and ICI in mice and men. We consider preclinical and clinical study design challenges and discuss the role of cancer type, exercise frequency, intensity, time, and type (FITT) and immune sensitivity as critical factors for exercise-induced impact on cancer immunosurveillance.

Low-density lipoprotein balances T cell metabolism and enhances response to anti-PD-1 blockade in a HCT116 spheroid model.

Introduction: The discovery of immune checkpoints and the development of their specific inhibitors was acclaimed as a major breakthrough in cancer therapy. However, only a limited patient cohort shows sufficient response to therapy. Hence, there is a need for identifying new checkpoints and predictive biomarkers with the objective of overcoming immune escape and resistance to treatment. Having been associated with both, treatment response and failure, LDL seems to be a double-edged sword in anti-PD1 immunotherapy. Being embedded into complex metabolic conditions, the impact of LDL on distinct immune cells has not been sufficiently addressed. Revealing the effects of LDL on T cell performance in tumor immunity may enable individual treatment adjustments in order to enhance the response to routinely administered immunotherapies in different patient populations. The object of this work was to investigate the effect of LDL on T cell activation and tumor immunity in-vitro. Methods: Experiments were performed with different LDL dosages (LDLlow = 50 µg/ml and LDLhigh = 200 µg/ml) referring to medium control. T cell phenotype, cytokines and metabolism were analyzed. The functional relevance of our findings was studied in a HCT116 spheroid model in the context of anti-PD-1 blockade. Results: The key points of our findings showed that LDLhigh skewed the CD4+ T cell subset into a central memory-like phenotype, enhanced the expression of the co-stimulatory marker CD154 (CD40L) and significantly reduced secretion of IL-10. The exhaustion markers PD-1 and LAG-3 were downregulated on both T cell subsets and phenotypical changes were associated with a balanced T cell metabolism, in particular with a significant decrease of reactive oxygen species (ROS). T cell transfer into a HCT116 spheroid model resulted in a significant reduction of the spheroid viability in presence of an anti-PD-1 antibody combined with LDLhigh. Discussion: Further research needs to be conducted to fully understand the impact of LDL on T cells in tumor immunity and moreover, to also unravel LDL effects on other lymphocytes and myeloid cells for improving anti-PD-1 immunotherapy. The reason for improved response might be a resilient, less exhausted phenotype with balanced ROS levels.

Acidity-mediated induction of FoxP3+ regulatory T cells.

Glucose limitation and increased lactic acid levels are consequences of the elevated glycolytic activity of tumor cells, and constitute a metabolic barrier for the function of tumor infiltrating effector immune cells. The immune-suppressive functions of regulatory T cells (Tregs) are unobstructed in lactic-acid rich environments. However, the impact of lactic acid on the induction of Tregs remains unknown. We observed increased TGFß-mediated induction of Forkhead box P3+ (FoxP3+ ) cells in the presence of extracellular lactic acid, in a glycolysis-independent, acidity-dependent manner. These CD4+ FoxP3+ cells expressed Treg-associated markers, including increased expression of CD39, and were capable of exerting suppressive functions. Corroborating these results in vivo, we observed that neutralizing the tumor pH by systemic administration of sodium bicarbonate (NaBi) decreased Treg abundance. We conclude that acidity augments Treg induction and propose that therapeutic targeting of acidity in the tumor microenvironment (TME) might reduce Treg-mediated immune suppression within tumors.

Glutamine synthetase expression rescues human dendritic cell survival in a glutamine-deprived environment.

Introduction: Glutamine deficiency is a well-known feature of the tumor environment. Here we analyzed the impact of glutamine deprivation on human myeloid cell survival and function. Methods: Different types of myeloid cells were cultured in the absence or presence of glutamine and/or with L-methionine-S-sulfoximine (MSO), an irreversible glutamine synthetase (GS) inhibitor. GS expression was analyzed on mRNA and protein level. GS activity and the conversion of glutamate to glutamine by myeloid cells was followed by 13C tracing analyses. Results: The absence of extracellular glutamine only slightly affected postmitotic human monocyte to dendritic cell (DC) differentiation, function and survival. Similar results were obtained for monocyte-derived macrophages. In contrast, proliferation of the monocytic leukemia cell line THP-1 was significantly suppressed. While macrophages exhibited high constitutive GS expression, glutamine deprivation induced GS in DC and THP-1. Accordingly, proliferation of THP-1 was rescued by addition of the GS substrate glutamate and 13C tracing analyses revealed conversion of glutamate to glutamine. Supplementation with the GS inhibitor MSO reduced the survival of DC and macrophages and counteracted the proliferation rescue of THP-1 by glutamate. Discussion: Our results show that GS supports myeloid cell survival in a glutamine poor environment. Notably, in addition to suppressing proliferation and survival of tumor cells, the blockade of GS also targets immune cells such as DCs and macrophages.

Expression of pH-Sensitive TRPC4 in Common Skin Tumors.

TRPCs (transient receptor potential classical or cation channels) play a crucial role in tumor biology, especially in the Ca2+ homeostasis in cancer cells. TRPC4 is a pH-sensitive member of this family of proteins. As solid tumors exhibit an inversed pH-gradient with lowered extracellular and increased intracellular pH, both contributing to tumor progression, TRPC4 might be a signaling molecule in the altered tumor microenvironment. This is the first study to investigate the expression profiles of TRPC4 in common skin cancers such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), malignant melanoma (MM) and nevus cell nevi (NCN). We found that all SCCs, NCNs, and MMs show positive TRPC4-expression, while BCCs do only in about half of the analyzed samples. These data render TRPC4 an immunohistochemical marker to distinguish SCC and BCC, and this also gives rise to future studies investigating the role of TRPC4 in tumor progression, and especially metastasis as BCCs very rarely spread and are mostly negative for TRPC4.

Targeting lactate metabolism for cancer immunotherapy - a matter of precision.

Immune checkpoint inhibitors and adoptive T cell therapies have been valuable additions to the toolbox in the fight against cancer. These treatments have profoundly increased the number of patients with a realistic perspective toward a return to a cancer-free life. Yet, in a number of patients and tumor entities, cancer immunotherapies have been ineffective so far. In solid tumors, immune exclusion and the immunosuppressive tumor microenvironment represent substantial roadblocks to successful therapeutic outcomes. A major contributing factor to the depressed anti-tumor activity of immune cells in tumors is the harsh metabolic environment. Hypoxia, nutrient competition with tumor and stromal cells, and accumulating noxious waste products, including lactic acid, pose massive constraints to anti-tumor immune cells. Numerous strategies are being developed to exploit the metabolic vulnerabilities of tumor cells in the hope that these would also alleviate metabolism-inflicted immune suppression. While promising in principle, especially in combination with immunotherapies, these strategies need to be scrutinized for their effect on tumor-fighting immune cells, which share some of their key metabolic properties with tumor cells. Here, we provide an overview of strategies that seek to tackle lactate metabolism in tumor or immune cells to unleash anti-tumor immune responses, thereby opening therapeutic options for patients whose tumors are currently not treatable.

Metabolic Heterogeneity of Brain Tumor Cells of Proneural and Mesenchymal Origin.

Brain-tumor-initiating cells (BTICs) of proneural and mesenchymal origin contribute to the highly malignant phenotype of glioblastoma (GB) and resistance to current therapies. BTICs of different subtypes were challenged with oxidative phosphorylation (OXPHOS) inhibition with metformin to assess the differential effects of metabolic intervention on key resistance features. Whereas mesenchymal BTICs varied according to their invasiveness, they were in general more glycolytic and less responsive to metformin. Proneural BTICs were less invasive, catabolized glucose more via the pentose phosphate pathway, and responded better to metformin. Targeting glycolysis may be a promising approach to inhibit tumor cells of mesenchymal origin, whereas proneural cells are more responsive to OXPHOS inhibition. Future clinical trials exploring metabolic interventions should account for metabolic heterogeneity of brain tumors.

Tachycardiomyopathy entails a dysfunctional pattern of interrelated mitochondrial functions.

Tachycardiomyopathy is characterised by reversible left ventricular dysfunction, provoked by rapid ventricular rate. While the knowledge of mitochondria advanced in most cardiomyopathies, mitochondrial functions await elucidation in tachycardiomyopathy. Pacemakers were implanted in 61 rabbits. Tachypacing was performed with 330 bpm for 10 days (n = 11, early left ventricular dysfunction) or with up to 380 bpm over 30 days (n = 24, tachycardiomyopathy, TCM). In n = 26, pacemakers remained inactive (SHAM). Left ventricular tissue was subjected to respirometry, metabolomics and acetylomics. Results were assessed for translational relevance using a human-based model: induced pluripotent stem cell derived cardiomyocytes underwent field stimulation for 7 days (TACH-iPSC-CM). TCM animals showed systolic dysfunction compared to SHAM (fractional shortening 37.8 ± 1.0% vs. 21.9 ± 1.2%, SHAM vs. TCM, p < 0.0001). Histology revealed cardiomyocyte hypertrophy (cross-sectional area 393.2 ± 14.5 µm2 vs. 538.9 ± 23.8 µm2, p < 0.001) without fibrosis. Mitochondria were shifted to the intercalated discs and enlarged. Mitochondrial membrane potential remained stable in TCM. The metabolite profiles of ELVD and TCM were characterised by profound depletion of tricarboxylic acid cycle intermediates. Redox balance was shifted towards a more oxidised state (ratio of reduced to oxidised nicotinamide adenine dinucleotide 10.5 ± 2.1 vs. 4.0 ± 0.8, p < 0.01). The mitochondrial acetylome remained largely unchanged. Neither TCM nor TACH-iPSC-CM showed relevantly increased levels of reactive oxygen species. Oxidative phosphorylation capacity of TCM decreased modestly in skinned fibres (168.9 ± 11.2 vs. 124.6 ± 11.45 pmol·O2·s-1·mg-1 tissue, p < 0.05), but it did not in isolated mitochondria. The pattern of mitochondrial dysfunctions detected in two models of tachycardiomyopathy diverges from previously published characteristic signs of other heart failure aetiologies.

LDHB Overexpression Can Partially Overcome T Cell Inhibition by Lactic Acid.

Accelerated glycolysis leads to secretion and accumulation of lactate and protons in the tumor environment and determines the efficacy of adoptive T cell and checkpoint inhibition therapy. Here, we analyzed effects of lactic acid on different human CD4 T cell subsets and aimed to increase CD4 T cell resistance towards lactic acid. In all CD4 T cell subsets analyzed, lactic acid inhibited metabolic activity (glycolysis and respiration), cytokine secretion, and cell proliferation. Overexpression of the lactate-metabolizing isoenzyme LDHB increased cell respiration and mitigated lactic acid effects on intracellular cytokine production. Strikingly, LDHB-overexpressing cells preferentially migrated into HCT116 tumor spheroids and displayed higher expression of cytotoxic effector molecules. We conclude, that LDHB overexpression might be a promising strategy to increase the efficacy of adoptive T cell transfer therapy.

Acidic Microenvironments Found in Cutaneous Leishmania Lesions Curtail NO-Dependent Antiparasitic Macrophage Activity.

Local tissue acidosis affects anti-tumor immunity. In contrast, data on tissue pH levels in infected tissues and their impact on antimicrobial activity is sparse. In this study, we assessed the pH levels in cutaneous Leishmania lesions. Leishmania major-infected skin tissue displayed pH levels of 6.7 indicating that lesional pH is acidic. Next, we tested the effect of low extracellular pH on the ability of macrophages to produce leishmanicidal NO and to fight the protozoan parasite Leishmania major. Extracellular acidification led to a marked decrease in both NO production and leishmanicidal activity of lipopolysaccharide (LPS) and interferon γ (IFN-γ)-coactivated macrophages. This was not directly caused by a disruption of NOS2 expression, a shortage of reducing equivalents (NAPDH) or substrate (L-arginine), but by a direct, pH-mediated inhibition of NOS2 enzyme activity. Normalization of intracellular pH significantly increased NO production and antiparasitic activity of macrophages even in an acidic microenvironment. Overall, these findings indicate that low local tissue pH can curtail NO production and leishmanicidal activity of macrophages.

Immunometabolic Markers in a Small Patient Cohort Undergoing Immunotherapy.

Although the discovery of immune checkpoints was hailed as a major breakthrough in cancer therapy, generating a sufficient response to immunotherapy is still limited. Thus, the objective of this exploratory, hypothesis-generating study was to identify potentially novel peripheral biomarkers and discuss the possible predictive relevance of combining scarcely investigated metabolic and hormonal markers with immune subsets. Sixteen markers that differed significantly between responders and non-responders were identified. In a further step, the correlation with progression-free survival (PFS) and false discovery correction (Benjamini and Hochberg) revealed potential predictive roles for the immune subset absolute lymphocyte count (rs = 0.51; p = 0.0224 *), absolute basophil count (rs = 0.43; p = 0.04 *), PD-1+ monocytes (rs = -0.49; p = 0.04 *), hemoglobin (rs = 0.44; p = 0.04 *), metabolic markers LDL (rs = 0.53; p = 0.0224 *), free androgen index (rs = 0.57; p = 0.0224 *) and CRP (rs = -0.46; p = 0.0352 *). The absolute lymphocyte count, LDL and free androgen index were the most significant individual markers, and combining the immune subsets with the metabolic markers into a biomarker ratio enhanced correlation with PFS (rs = -0.74; p ≤ 0.0001 ****). In summary, in addition to well-established markers, we identified PD-1+ monocytes and the free androgen index as potentially novel peripheral markers in the context of immunotherapy. Furthermore, the combination of immune subsets with metabolic and hormonal markers may have the potential to enhance the power of future predictive scores and should, therefore, be investigated further in larger trials.

Physiological levels of 25-hydroxyvitamin D3 induce a suppressive CD4+ T cell phenotype not reflected in the epigenetic landscape.

1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ), the active metabolite of vitamin D3 has a strong impact on the differentiation and function of immune cells. Here we analysed the influence of its precursor 25-hydroxyvitamin D3 (25(OH)D3 ) on the differentiation of human CD4+ T cells applying physiological concentrations in vitro. Our data show that 25(OH)D3 is converted to its active form 1,25(OH)2 D3 by T cells, which in turn supports FOXP3, CD25 and CTLA-4 expression and inhibits IFN-γ production. These changes were not reflected in the demethylation of the respective promoters. Furthermore, we investigated the impact of vitamin D3 metabolites under induced Treg (iTreg) polarization conditions using TGF-ß. Surprisingly, no additive effect but a decreased percentage of FOXP3 expressing cells was observed. However, the combination of 25(OH)D3 or 1,25(OH)2 D3 together with TGF-ß further upregulated CD25 and CTLA-4 and significantly increased soluble CTLA-4 and IL-10 secretion whereas IFN-γ expression of iTreg was decreased. Our data suggest that physiological levels of 25(OH)D3 act as potent modulator of human CD4+ T cells and autocrine or paracrine production of 1,25(OH)2 D3 by T cells might be crucial for the local regulation of an adaptive immune response. However, since no epigenetic changes are detected by 25(OH)D3 a rather transient phenotype is induced.

Kynurenine induces T cell fat catabolism and has limited suppressive effects in vivo.

BACKGROUND: L-kynurenine is a tryptophan-derived immunosuppressive metabolite and precursor to neurotoxic anthranilate and quinolinate. We evaluated the stereoisomer D-kynurenine as an immunosuppressive therapeutic which is hypothesized to produce less neurotoxic metabolites than L-kynurenine. METHODS: L-/D-kynurenine effects on human and murine T cell function were examined in vitro and in vivo (homeostatic proliferation, colitis, cardiac transplant). Kynurenine effects on T cell metabolism were interrogated using [13C] glucose, glutamine and palmitate tracing. Kynurenine was measured in tissues from human and murine tumours and kynurenine-fed mice. FINDINGS: We observed that 1 mM D-kynurenine inhibits T cell proliferation through apoptosis similar to L-kynurenine. Mechanistically, [13C]-tracing revealed that co-stimulated CD4+ T cells exposed to L-/D-kynurenine undergo increased ß-oxidation depleting fatty acids. Replenishing oleate/palmitate restored effector T cell viability. We administered dietary D-kynurenine reaching tissue kynurenine concentrations of 19 µM, which is close to human kidney (6 µM) and head and neck cancer (14 µM) but well below the 1 mM required for apoptosis. D-kynurenine protected Rag1-/- mice from autoimmune colitis in an aryl-hydrocarbon receptor dependent manner but did not attenuate more stringent immunological challenges such as antigen mismatched cardiac allograft rejection. INTERPRETATION: Our dietary kynurenine model achieved tissue concentrations at or above human cancer kynurenine and exhibited only limited immunosuppression. Sub-suppressive kynurenine concentrations in human cancers may limit the responsiveness to indoleamine 2,3-dioxygenase inhibition evaluated in clinical trials. FUNDING: The study was supported by the NIH, the Else Kröner-Fresenius-Foundation, Laffey McHugh foundation, and American Society of Nephrology.

Metabolic imbalance of T cells in COVID-19 is hallmarked by basigin and mitigated by dexamethasone.

Metabolic pathways regulate immune responses and disrupted metabolism leads to immune dysfunction and disease. Coronavirus disease 2019 (COVID-19) is driven by imbalanced immune responses, yet the role of immunometabolism in COVID-19 pathogenesis remains unclear. By investigating 87 patients with confirmed SARS-CoV-2 infection, 6 critically ill non-COVID-19 patients, and 47 uninfected controls, we found an immunometabolic dysregulation in patients with progressed COVID-19. Specifically, T cells, monocytes, and granulocytes exhibited increased mitochondrial mass, yet only T cells accumulated intracellular reactive oxygen species (ROS), were metabolically quiescent, and showed a disrupted mitochondrial architecture. During recovery, T cell ROS decreased to match the uninfected controls. Transcriptionally, T cells from severe/critical COVID-19 patients showed an induction of ROS-responsive genes as well as genes related to mitochondrial function and the basigin network. Basigin (CD147) ligands cyclophilin A and the SARS-CoV-2 spike protein triggered ROS production in T cells in vitro. In line with this, only PCR-positive patients showed increased ROS levels. Dexamethasone treatment resulted in a downregulation of ROS in vitro and T cells from dexamethasone-treated patients exhibited low ROS and basigin levels. This was reflected by changes in the transcriptional landscape. Our findings provide evidence of an immunometabolic dysregulation in COVID-19 that can be mitigated by dexamethasone treatment.

Targeting Cancer Metabolism Breaks Radioresistance by Impairing the Stress Response.

The heightened energetic demand increases lactate dehydrogenase (LDH) activity, the corresponding oncometabolite lactate, expression of heat shock proteins (HSPs) and thereby promotes therapy resistance in many malignant tumor cell types. Therefore, we assessed the coregulation of LDH and the heat shock response with respect to radiation resistance in different tumor cells (B16F10 murine melanoma and LS174T human colorectal adenocarcinoma). The inhibition of LDH activity by oxamate or GNE-140, glucose deprivation and LDHA/B double knockout (LDH-/-) in B16F10 and LS174T cells significantly diminish tumor growth; ROS production and the cytosolic expression of different HSPs, including Hsp90, Hsp70 and Hsp27 concomitant with a reduction of heat shock factor 1 (HSF1)/pHSF1. An altered lipid metabolism mediated by a LDHA/B double knockout results in a decreased presence of the Hsp70-anchoring glycosphingolipid Gb3 on the cell surface of tumor cells, which, in turn, reduces the membrane Hsp70 density and increases the extracellular Hsp70 levels. Vice versa, elevated extracellular lactate/pyruvate concentrations increase the membrane Hsp70 expression in wildtype tumor cells. Functionally, an inhibition of LDH causes a generalized reduction of cytosolic and membrane-bound HSPs in tumor cells and significantly increases the radiosensitivity, which is associated with a G2/M arrest. We demonstrate that targeting of the lactate/pyruvate metabolism breaks the radioresistance by impairing the stress response.

Gender specific airway gene expression in COPD sub-phenotypes supports a role of mitochondria and of different types of leukocytes.

Chronic obstructive pulmonary disease (COPD) is a destructive inflammatory disease and the genes expressed within the lung are crucial to its pathophysiology. We have determined the RNAseq transcriptome of bronchial brush cells from 312 stringently defined ex-smoker patients. Compared to healthy controls there were for males 40 differentially expressed genes (DEGs) and 73 DEGs for females with only 26 genes shared. The gene ontology (GO) term "response to bacterium" was shared, with several different DEGs contributing in males and females. Strongly upregulated genes TCN1 and CYP1B1 were unique to males and females, respectively. For male emphysema (E)-dominant and airway disease (A)-dominant COPD (defined by computed tomography) the term "response to stress" was found for both sub-phenotypes, but this included distinct up-regulated genes for the E-sub-phenotype (neutrophil-related CSF3R, CXCL1, MNDA) and for the A-sub-phenotype (macrophage-related KLF4, F3, CD36). In E-dominant disease, a cluster of mitochondria-encoded (MT) genes forms a signature, able to identify patients with emphysema features in a confirmation cohort. The MT-CO2 gene is upregulated transcriptionally in bronchial epithelial cells with the copy number essentially unchanged. Both MT-CO2 and the neutrophil chemoattractant CXCL1 are induced by reactive oxygen in bronchial epithelial cells. Of the female DEGs unique for E- and A-dominant COPD, 88% were detected in females only. In E-dominant disease we found a pronounced expression of mast cell-associated DEGs TPSB2, TPSAB1 and CPA3. The differential genes discovered in this study point towards involvement of different types of leukocytes in the E- and A-dominant COPD sub-phenotypes in males and females.