bims-mepmim 2022-07-10 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2022–07–10
thirty papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

Uncovering the source of mitochondrial superoxide in pro-inflammatory macrophages: Insights from immunometabolism.
Dysregulated metabolism: A friend-to-foe skewer of macrophages.
13C tracer analysis suggests extensive recycling of endogenous CO2 in vivo.
Driving with Both Feet: Supplementing AKG While Inhibiting BCAT1 Leads to Synthetic Lethality in GBM.
N6-methyladenosine modification and metabolic reprogramming of digestive system malignancies.
Tumor cells modulate macrophage phenotype in a novel in vitro co-culture model of the non-small cell lung cancer tumor microenvironment.
An Iron Refractory Phenotype in Obese Adipose Tissue Macrophages Leads to Adipocyte Iron Overload.
Chronic Fatty Acid Depletion Induces Uncoupling Protein 1 (UCP1) Expression to Coordinate Mitochondrial Inducible Proton Leak in a Human-Brown-Adipocyte Model.
Macrophages activated by hepatitis B virus have distinct metabolic profiles and suppress the virus via IL-1β to downregulate PPARα and FOXO3.
Noncoding RNAs: Regulating the crosstalk between tumor-associated macrophages and gastrointestinal cancer.
Methionine deficiency facilitates antitumour immunity by altering m6A methylation of immune checkpoint transcripts.
Pharmacological inhibition of sphingolipid synthesis reduces ferroptosis by stimulating the HIF-1 pathway.
Neutrophils in the tumor microenvironment and their functional modulation by mesenchymal stromal cells.
Metabolic Labeling-Based Chemoproteomics Establishes Choline Metabolites as Protein Function Modulators.
Metabolic discrimination of synovial fluid between rheumatoid arthritis and osteoarthritis using gas chromatography/time-of-flight mass spectrometry.
Crosstalk among m6A RNA methylation, hypoxia and metabolic reprogramming in TME: from immunosuppressive microenvironment to clinical application.
The Possible Role of Glucose-6-Phosphate Dehydrogenase in the SARS-CoV-2 Infection.
Pesticides Exposure-Induced Changes in Brain Metabolome: Implications in the Pathogenesis of Neurodegenerative Disorders.
Octanoic Acid-Enrichment Diet Improves Endurance Capacity and Reprograms Mitochondrial Biogenesis in Skeletal Muscle of Mice.
Modulation of adipose inflammation by cellular retinoic acid-binding protein 1.
Specific ATPases drive compartmentalized glycogen utilization in rat skeletal muscle.
Mitochondrial GCN5L1 regulates cytosolic redox state and hepatic gluconeogenesis via glycerol phosphate shuttle GPD2.
The Novel Immune Checkpoint GPR56 Is Expressed on Tumor-Infiltrating Lymphocytes and Selectively Upregulated upon TCR Signaling.
Targeting UDP-α-d-glucose 6-dehydrogenase alters the CNS tumor immune microenvironment and inhibits glioblastoma growth.
Essential lipid autacoids rewire mitochondrial energy efficiency in metabolic dysfunction-associated fatty liver disease.
Compromised glycolysis contributes to foot process fusion of podocytes in diabetic kidney disease: Role of ornithine catabolism.
Spatial transcriptomics atlas reveals the crosstalk between cancer-associated fibroblasts and tumor microenvironment components in colorectal cancer.
Chronic Hyperglycaemia Inhibits Tricarboxylic Acid Cycle in Rat Cardiomyoblasts Overexpressing Glucose Transporter Type 4.
New Avenues of Heme Synthesis Regulation.
Targeted therapy of pyrrolo[2,3-d]pyrimidine antifolates in a syngeneic mouse model of high grade serous ovarian cancer and the impact on the tumor microenvironment.

Biochim Biophys Acta Mol Basis Dis. 2022 Jul 02. pii: S0925-4439(22)00152-1. [Epub ahead of print] 166481

Uncovering the source of mitochondrial superoxide in pro-inflammatory macrophages: Insights from immunometabolism.

Alva M Casey, Michael P Murphy.

  Mitochondrial-derived reactive oxygen species are important as antimicrobial agents and redox signals in pro-inflammatory macrophages. Macrophages produce superoxide in response to the TLR4 ligand LPS. However, the mechanism of LPS-induced superoxide generation is not fully understood. Superoxide is produced at complex I and complex III of the electron transport chain. Production of superoxide at either of these sites is highly dependent on the metabolic state of the cell which is dramatically altered by TLR4-induced metabolic reprogramming. This review will outline how metabolism impacts superoxide production in LPS-activated macrophages downstream of TLR4 signalling and address outstanding questions in this field.

Keywords:  Complex I; Macrophages; Metabolism; Mitochondria; Reverse electron transport; Superoxide

DOI:  https://doi.org/10.1016/j.bbadis.2022.166481
Int Rev Immunol. 2022 Jul 06. 1-17

Dysregulated metabolism: A friend-to-foe skewer of macrophages.

Keywan Mortezaee, Jamal Majidpoor.

  Metabolic reprogramming is a hallmark of solid cancers. Macrophages as major constituents of immune system take important roles in regulation of tumorigenesis. Pro-tumor M2 macrophages preferentially use oxidative phosphorylation (OXPHOS) to meet their metabolic demands, while anti-tumor M1 macrophages use glycolysis as their dominant metabolic source. Dysregulation in metabolic systems is a driving force of skewing macrophages from M1 toward M2 phenotypical state. Hyperactive M1 macrophages, for instance, release metabolic products that are contributed to M2 macrophage polarization. Thus, metabolic remodeling through reinstating normalization in metabolic systems can be an effective tool in cancer therapy. The key focus of this review is over metabolic systems in macrophages and factors influencing their metabolic acquisition and reprogramming in cancer, as well as discussing bout strategies to adjust macrophage metabolism and reeducation toward M1-like phenotype.

Keywords:  Tumor microenvironment (TME); glycolysis; hypoxia; hypoxia inducible factor (HIF); lactate; macrophage; metabolism; oxidative phosphorylation (OXPHOS)

DOI:  https://doi.org/10.1080/08830185.2022.2095374
Cancer Metab. 2022 Jul 07. 10(1): 11

13C tracer analysis suggests extensive recycling of endogenous CO2 in vivo.

Likun Duan, Daniel E Cooper, Grace Scheidemantle, Jason W Locasale, David G Kirsch, Xiaojing Liu.

   BACKGROUND: 13C tracer analysis is increasingly used to monitor cellular metabolism in vivo and in intact cells, but data interpretation is still the key element to unveil the complexity of metabolic activities. The distinct 13C labeling patterns (e.g., M + 1 species in vivo but not in vitro) of metabolites from [U-13C]-glucose or [U-13C]-glutamine tracing in vivo and in vitro have been previously reported by multiple groups. However, the reason for the difference in the M + 1 species between in vivo and in vitro experiments remains poorly understood.
METHODS: We have performed [U-13C]-glucose and [U-13C]-glutamine tracing in sarcoma-bearing mice (in vivo) and in cancer cell lines (in vitro). 13C enrichment of metabolites in cultured cells and tissues was determined by LC coupled with high-resolution mass spectrometry (LC-HRMS). All p-values are obtained from the Student's t-test two-tailed using GraphPad Prism 8 unless otherwise noted.
RESULTS: We observed distinct enrichment patterns of tricarboxylic acid cycle intermediates in vivo and in vitro. As expected, citrate M + 2 or M + 4 was the dominant mass isotopologue in vitro. However, citrate M + 1 was unexpectedly the dominant isotopologue in mice receiving [U-13C]-glucose or [U-13C]-glutamine infusion, but not in cultured cells. Our results are consistent with a model where the difference in M + 1 species is due to the different sources of CO2 in vivo and in vitro, which was largely overlooked in the past. In addition, a time course study shows the generation of high abundance citrate M + 1 in plasma of mice as early as few minutes after [U-13C]-glucose infusion.
CONCLUSIONS: Altogether, our results show that recycling of endogenous CO2 is substantial in vivo. The production and recycling of 13CO2 from the decarboxylation of [U-13C]-glucose or [U-13C]-glutamine is negligible in vitro partially due to dilution by the exogenous HCO3-/CO2 source, but in vivo incorporation of endogenous 13CO2 into M + 1 metabolites is substantial and should be considered. These findings provide a new paradigm to understand carbon atom transformations in vivo and should be taken into account when developing mathematical models to better reflect carbon flux.

Keywords:  13C tracing; Anaplerotic metabolism; CO2 recycling; High-resolution mass spectrometry

DOI:  https://doi.org/10.1186/s40170-022-00287-8
Cancer Res. 2022 Jul 05. 82(13): 2354-2356

Driving with Both Feet: Supplementing AKG While Inhibiting BCAT1 Leads to Synthetic Lethality in GBM.

Noah Meurs, Deepak Nagrath.

Understanding how carcinogenesis can expose cancers to synthetically lethal vulnerabilities has been an essential underpinning of development of modern anticancer therapeutics. Isocitrate dehydrogenase wild-type (IDHWT) glioblastoma multiforme (GBM), which is known to have upregulated branched-chain amino acid transaminase 1 (BCAT1) expression, has not had treatments developed to the same extent as the IDH mutant counterpart, despite making up the majority of cases. In this issue, Zhang and colleagues utilize a metabolic screen to identify α-ketoglutarate (AKG) as a synthetically lethal treatment in conjunction with BCAT1 inhibition in IDHWT GBM. These treatments synergize in a multipronged approach that limits substrate catabolism and disrupts mitochondrial homeostasis through perturbing the balance of NAD+/NADH, leading to mTORC1 inhibition and a reduction of nucleotide biosynthesis. Based on these results, the authors propose combination treatment targeting branched chain amino acid catabolism as a potential option for patients with IDHWT GBM. See related article by Zhang et al., p. 2388.

DOI: https://doi.org/10.1158/0008-5472.CAN-22-1619
Cancer Lett. 2022 Jul 04. pii: S0304-3835(22)00299-3. [Epub ahead of print] 215815

N6-methyladenosine modification and metabolic reprogramming of digestive system malignancies.

Xianlei Cai, Chao Liang, Miaozun Zhang, Yuan Xu, Yihui Weng, Xueying Li, Weiming Yu.

  N6-methyladenosine (m6A) is a eukaryotic post-transcriptional modification involved in cell growth and developmental processes, including RNA transcription, alternative splicing, degradation, and translation. It is also involved in the development of various cancers. Metabolic reprogramming enables cancer cells to obtain nutrition from the tumor microenvironment, which is a hallmark of cancer. Numerous studies have shown that m6A modification induces metabolic reprogramming in cancer by regulating the expression of metabolic core genes or activation of metabolic signaling pathways. Digestive system malignancies include esophageal, gastric, colorectal, liver, pancreatic, and other cancers, all of which are associated with poor outcomes. This review summarizes the role of m6A modification in the metabolic reprogramming of digestive system malignancies, with the aim of identifying therapeutic strategies.

Keywords:  Epigenetic modification; Glucose metabolism; Glutamine metabolism; Lipid metabolism

DOI:  https://doi.org/10.1016/j.canlet.2022.215815
J Thorac Oncol. 2022 Jul 04. pii: S1556-0864(22)00315-X. [Epub ahead of print]

Tumor cells modulate macrophage phenotype in a novel in vitro co-culture model of the non-small cell lung cancer tumor microenvironment.

Josiah Voth Park, Raghav Chandra, Ling Cai, Debolina Ganguly, Huiyu Li, Jason E Toombs, Luc Girard, Rolf A Brekken, John D Minna.

   INTRODUCTION: Macrophage phenotype in the tumor microenvironment correlates with prognosis in non-small cell lung cancer (NSCLC). Immunosuppressive macrophages promote tumor progression, while pro-inflammatory macrophages may drive an anti-tumor immune response. How individual NSCLCs impact macrophage phenotype is a major knowledge gap.
METHODS: To systematically study the impact of lung cancer cells on macrophage phenotypes, we developed an in vitro co-culture model comprised of molecularly and clinically-annotated patient-derived NSCLC lines, human cancer-associated fibroblasts, and murine macrophages. Induced macrophage phenotype was studied through qRT-PCR and validated in vivo using NSCLC xenografts through quantitative immunohistochemistry and clinically with TCGA "matched" patient tumors.
RESULTS: 72 NSCLC cell lines were studied. The most frequent highly induced macrophage-related gene was Arginase-1, reflecting an immunosuppressive M2-like phenotype. This was independent of multiple clinicopathologic factors, which also did not impact M2:M1 ratios in matched TCGA samples. In vivo, xenograft tumors established from high Arginase-1-inducing lines (Arghi) had a significantly elevated density of Arg1+ macrophages. Matched TCGA clinical samples to Arghi NSCLC lines had a significantly higher ratio of M2:M1 macrophages.
CONCLUSIONS: In our in vitro co-culture model, a large panel of patient-derived NSCLC lines most frequently induced high expression Arginase-1 in co-cultured mouse macrophages, independent of major clinicopathologic and oncogenotype-related factors. Arghi cluster-matched TCGA tumors contained a higher ratio of M2:M1 macrophages. Thus, this in vitro model reproducibly characterizes how individual NSCLCs modulate macrophage phenotype, correlates with macrophage polarization in clinical samples, and can serve as an accessible platform for further investigation of macrophage-specific therapeutic strategies.

Keywords:  Non-small cell lung cancer; in vitro co-culture model; macrophage phenotype; tumor microenvironment

DOI:  https://doi.org/10.1016/j.jtho.2022.06.011
Int J Mol Sci. 2022 Jul 03. pii: 7417. [Epub ahead of print]23(13):

An Iron Refractory Phenotype in Obese Adipose Tissue Macrophages Leads to Adipocyte Iron Overload.

Magdalene K Ameka, William N Beavers, Ciara M Shaver, Lorraine B Ware, Vern Eric Kerchberger, Kelly Q Schoenfelt, Lili Sun, Tatsuki Koyama, Eric P Skaar, Lev Becker, Alyssa H Hasty.

  Adipocyte iron overload is a maladaptation associated with obesity and insulin resistance. The objective of the current study was to determine whether and how adipose tissue macrophages (ATMs) regulate adipocyte iron concentrations and whether this is impacted by obesity. Using bone marrow-derived macrophages (BMDMs) polarized to M0, M1, M2, or metabolically activated (MMe) phenotypes, we showed that MMe BMDMs and ATMs from obese mice have reduced expression of several iron-related proteins. Furthermore, the bioenergetic response to iron in obese ATMs was hampered. ATMs from iron-injected lean mice increased their glycolytic and respiratory capacities, thus maintaining metabolic flexibility, while ATMs from obese mice did not. Using an isotope-based system, we found that iron exchange between BMDMs and adipocytes was regulated by macrophage phenotype. At the end of the co-culture, MMe macrophages transferred and received more iron from adipocytes than M0, M1, and M2 macrophages. This culminated in a decrease in total iron in MMe macrophages and an increase in total iron in adipocytes compared with M2 macrophages. Taken together, in the MMe condition, the redistribution of iron is biased toward macrophage iron deficiency and simultaneous adipocyte iron overload. These data suggest that obesity changes the communication of iron between adipocytes and macrophages and that rectifying this iron communication channel may be a novel therapeutic target to alleviate insulin resistance.

Keywords:  adipose tissue macrophage; immunometabolism; iron; obesity; polarization

DOI:  https://doi.org/10.3390/ijms23137417
Cells. 2022 Jun 27. pii: 2038. [Epub ahead of print]11(13):

Chronic Fatty Acid Depletion Induces Uncoupling Protein 1 (UCP1) Expression to Coordinate Mitochondrial Inducible Proton Leak in a Human-Brown-Adipocyte Model.

Yukimasa Takeda, Ping Dai.

  Thermogenic brown fat contributes to metabolic health in adult humans. Obese conditions are known to repress adipose-tissue browning and its activity. Herein, we found that chronic fatty acid (FA) depletion induced uncoupling protein 1 (UCP1) expression in the chemical-compound-induced brown adipocytes (ciBAs). The ciBAs, converted from human dermal fibroblasts under FA-free conditions, had low intracellular triglyceride levels and strongly activated UCP1 expression. Prolonged treatment with carnitine also reduced triglyceride accumulation and induced UCP1 expression. Transcriptome analysis revealed that the UCP1 induction was accompanied by the activation of lipid metabolic genes. The FA-depleted conditions repressed mitochondrial proton-leak activity and mitochondrial membrane potential (MMP), despite maintaining a high UCP1 expression. The evidence suggested that UCP1 expression was induced to compensate for the proton-leak activity under low MMP. Our study reports a regulatory mechanism underlying UCP1 expression and mitochondrial-energy status in human brown adipocytes under different nutritional conditions.

Keywords:  human brown adipocytes; lipid metabolism; mitochondria; obesity; transcriptome analysis; uncoupling protein 1

DOI:  https://doi.org/10.3390/cells11132038
Cell Rep. 2022 Jul 05. pii: S2211-1247(22)00866-X. [Epub ahead of print]40(1): 111068

Macrophages activated by hepatitis B virus have distinct metabolic profiles and suppress the virus via IL-1β to downregulate PPARα and FOXO3.

Yumei Li, Yanwen Zhu, Shu Feng, Yuji Ishida, Tsu-Pei Chiu, Takeshi Saito, Sean Wang, David K Ann, Jing-Hsiung James Ou.

DOI: https://doi.org/10.1016/j.celrep.2022.111068
Biomed Pharmacother. 2022 Jul 02. pii: S0753-3322(22)00759-4. [Epub ahead of print]153 113370

Noncoding RNAs: Regulating the crosstalk between tumor-associated macrophages and gastrointestinal cancer.

Bingyu Wang, Bibo Tan.

  Gastrointestinal (GI) cancers, one of the most lethal cancers nowadays, have caused millions of deaths. The tumor microenvironment (TME) is a complex ecosystem containing multiple cells, such as immune cells, cancer cells, and endothelial cells. Tumor-associated macrophages (TAMs), the predominant cells infiltrating the TME, have been verified to play a crucial role in regulating tumor progression. Noncoding RNAs (ncRNAs) are involved in mediating tumor-infiltrating immune cells, including TAMs. GI cancer cells produce various ncRNAs to modulate TAM infiltration and polarization. Meanwhile, ncRNAs play a pivotal role in macrophage and cancer cell metabolic reprogramming. Furthermore, macrophages mediate the impact of ncRNAs on chemoresistance, metastasis, and progression of GI cancer. In this review, we summarize recent research advances in the crosstalk between macrophages and GI cancer regulated by ncRNAs. Moreover, we propose the promising role of ncRNAs as potential targets and prognostic biomarkers in cancer treatment, hoping to facilitate the identification of new targets for immunotherapy.

Keywords:  Gastrointestinal cancer; Non-coding RNAs; Tumor-associated macrophages

DOI:  https://doi.org/10.1016/j.biopha.2022.113370
Gut. 2022 Jul 08. pii: gutjnl-2022-326928. [Epub ahead of print]

Methionine deficiency facilitates antitumour immunity by altering m6A methylation of immune checkpoint transcripts.

Ting Li, Yue-Tao Tan, Yan-Xing Chen, Xiao-Jun Zheng, Wen Wang, Kun Liao, Hai-Yu Mo, Junzhong Lin, Wei Yang, Hai-Long Piao, Rui-Hua Xu, Huai-Qiang Ju.

   OBJECTIVE: Methionine metabolism is involved in a myriad of cellular functions, including methylation reactions and redox maintenance. Nevertheless, it remains unclear whether methionine metabolism, RNA methylation and antitumour immunity are molecularly intertwined.
DESIGN: The antitumour immunity effect of methionine-restricted diet (MRD) feeding was assessed in murine models. The mechanisms of methionine and YTH domain-containing family protein 1 (YTHDF1) in tumour immune escape were determined in vitro and in vivo. The synergistic effects of MRD or YTHDF1 depletion with PD-1 blockade were also investigated.
RESULTS: We found that dietary methionine restriction reduced tumour growth and enhanced antitumour immunity by increasing the number and cytotoxicity of tumour-infiltrating CD8+ T cells in different mouse models. Mechanistically, the S-adenosylmethionine derived from methionine metabolism promoted the N6-methyladenosine (m6A) methylation and translation of immune checkpoints, including PD-L1 and V-domain Ig suppressor of T cell activation (VISTA), in tumour cells. Furthermore, MRD or m6A-specific binding protein YTHDF1 depletion inhibited tumour growth by restoring the infiltration of CD8+ T cells, and synergised with PD-1 blockade for better tumour control. Clinically, YTHDF1 expression correlated with poor prognosis and immunotherapy outcomes for cancer patients.
CONCLUSIONS: Methionine and YTHDF1 play a critical role in anticancer immunity through regulating the functions of T cells. Targeting methionine metabolism or YTHDF1 could be a potential new strategy for cancer immunotherapy.

Keywords:  colorectal cancer; immunotherapy; methylation

DOI:  https://doi.org/10.1136/gutjnl-2022-326928
iScience. 2022 Jul 15. 25(7): 104533

Pharmacological inhibition of sphingolipid synthesis reduces ferroptosis by stimulating the HIF-1 pathway.

Yang Liu, Libo He, Binghua Liu, Yuling Ying, Junling Xu, Meng Yu, Jinye Dang, Ke Liu.

  Ferroptosis is crucial to the pathology of many neurological diseases. Here, we found pre-treatment with myriocin, an inhibitor of de novo synthesis of sphingolipid, significantly decreased the erastin- or glutamate-induced ferroptosis of HT22 cells without requiring the recovery of intracellular glutathione. The transcriptome analysis of HT22 cells treated with or without myriocin identified the hypoxia-inducible factor 1 (HIF-1) pathway as a prime and novel drug target. Further study validated that HIF1α was required for the cytoprotective effects of myriocin. Myriocin treatment promoted the expression of HIF-1 pathway effectors including PDK1 and BNIP3 and altered the intracellular levels of glucose metabolites. Additionally, myriocin treatment stabilized HIF1α protein by decreasing its ubiquitination and proteasomal degradation. Similar effects of myriocin on HIF1α stabilization were also found in other mammalian cell lines indicating this is a common mechanism for the cytoprotective role of myriocin.

Keywords:  Biological sciences; Cell biology; Cellular neuroscience; Neuroscience

DOI:  https://doi.org/10.1016/j.isci.2022.104533
Cell Immunol. 2022 Jul 01. pii: S0008-8749(22)00101-0. [Epub ahead of print]379 104576

Neutrophils in the tumor microenvironment and their functional modulation by mesenchymal stromal cells.

Zhiyuan Zheng, Yazhang Xu, Yufang Shi, Changshun Shao.

  Neutrophils are the most predominant cell population in the innate immune system. The role of neutrophils in the initiation, development and metastasis of tumor has been actively studied in recent years. In cancer, neutrophils exert both pro- and anti-cancer effects, and their phenotype and function are affected by the tumor microenvironment (TME). This review aims to summarize the role of neutrophils in tumorigenesis with emphasis on their interaction with mesenchymal stromal cells (MSCs).

Keywords:  Mesenchymal stromal cells; Metastasis; Neutrophils; Tumor microenvironment

DOI:  https://doi.org/10.1016/j.cellimm.2022.104576
ACS Chem Biol. 2022 Jul 08.

Metabolic Labeling-Based Chemoproteomics Establishes Choline Metabolites as Protein Function Modulators.

Aditi Dixit, Gregor P Jose, Chitra Shanbhag, Nitin Tagad, Jeet Kalia.

Choline is an essential nutrient for mammalian cells. Our understanding of the cellular functions of choline and its metabolites, independent of their roles as choline lipid metabolism intermediates, remains limited. In addition to fundamental cellular physiology, this knowledge has implications for cancer biology because elevated choline metabolite levels are a hallmark of cancer. Here, we establish a mammalian choline metabolite-interacting proteome by utilizing a photocrosslinkable choline probe. To design this probe, we performed metabolic labeling experiments with structurally diverse choline analogues that resulted in the serendipitous discovery of a choline lipid headgroup remodeling mechanism involving sequential dealkylation and methylation steps. We demonstrate that phosphocholine inhibits the binding of one of the proteins identified, the attractive anticancer target p32, to its endogenous ligands and to the promising p32-targeting anticancer agent, Lyp-1. Our results reveal that choline metabolites play vital roles in cellular physiology by serving as modulators of protein function.

DOI: https://doi.org/10.1021/acschembio.2c00400
Metabolomics. 2022 Jul 04. 18(7): 48

Metabolic discrimination of synovial fluid between rheumatoid arthritis and osteoarthritis using gas chromatography/time-of-flight mass spectrometry.

Sooah Kim, Jiwon Hwang, Jungyeon Kim, Sun-Hee Lee, Yu Eun Cheong, Seulkee Lee, Kyoung Heon Kim, Hoon-Suk Cha.

   INTRODUCTION: Rheumatoid arthritis (RA) and osteoarthritis (OA) are clinicopathologically different.
OBJECTIVES: We aimed to assess the feasibility of metabolomics in differentiating the metabolite profiles of synovial fluid between RA and OA using gas chromatography/time-of-flight mass spectrometry.
METHODS: We first compared the global metabolomic changes in the synovial fluid of 19 patients with RA and OA. Partial least squares-discriminant, hierarchical clustering, and univariate analyses were performed to distinguish metabolites of RA and OA. These findings were then validated using synovial fluid samples from another set of 15 patients with RA and OA.
RESULTS: We identified 121 metabolites in the synovial fluid of the first 19 samples. The score plot of PLS-DA showed a clear separation between RA and OA. Twenty-eight crucial metabolites, including hypoxanthine, xanthine, adenosine, citrulline, histidine, and tryptophan, were identified to be capable of distinguishing RA metabolism from that of OA; these were found to be associated with purine and amino acid metabolism.
CONCLUSION: Our results demonstrated that metabolite profiling of synovial fluid could clearly discriminate between RA and OA, suggesting that metabolomics may be a feasible tool to assist in the diagnosis and advance the comprehension of pathological processes for diseases.

Keywords:  Gas chromatography–mass spectrometry; Metabolite profiling; Osteoarthritis; Rheumatoid arthritis; Synovial fluid

DOI:  https://doi.org/10.1007/s11306-022-01893-9
J Hematol Oncol. 2022 Jul 06. 15(1): 84

Crosstalk among m6A RNA methylation, hypoxia and metabolic reprogramming in TME: from immunosuppressive microenvironment to clinical application.

Fusheng Zhang, Haiyang Liu, Meiqi Duan, Guang Wang, Zhenghou Zhang, Yutian Wang, Yiping Qian, Zhi Yang, Xiaofeng Jiang.

  The tumor microenvironment (TME), which is regulated by intrinsic oncogenic mechanisms and epigenetic modifications, has become a research hotspot in recent years. Characteristic features of TME include hypoxia, metabolic dysregulation, and immunosuppression. One of the most common RNA modifications, N6-methyladenosine (m6A) methylation, is widely involved in the regulation of physiological and pathological processes, including tumor development. Compelling evidence indicates that m6A methylation regulates transcription and protein expression through shearing, export, translation, and processing, thereby participating in the dynamic evolution of TME. Specifically, m6A methylation-mediated adaptation to hypoxia, metabolic dysregulation, and phenotypic shift of immune cells synergistically promote the formation of an immunosuppressive TME that supports tumor proliferation and metastasis. In this review, we have focused on the involvement of m6A methylation in the dynamic evolution of tumor-adaptive TME and described the detailed mechanisms linking m6A methylation to change in tumor cell biological functions. In view of the collective data, we advocate treating TME as a complete ecosystem in which components crosstalk with each other to synergistically achieve tumor adaptive changes. Finally, we describe the potential utility of m6A methylation-targeted therapies and tumor immunotherapy in clinical applications and the challenges faced, with the aim of advancing m6A methylation research.

Keywords:  Exosomes; Hypoxia; Immune escape; Tumor biological functions; Tumor combination therapy; Tumor metabolism

DOI:  https://doi.org/10.1186/s13045-022-01304-5
Cells. 2022 Jun 21. pii: 1982. [Epub ahead of print]11(13):

The Possible Role of Glucose-6-Phosphate Dehydrogenase in the SARS-CoV-2 Infection.

Israel Pérez-Torres, María Elena Soto, Verónica Guarner-Lans, Linaloe Manzano-Pech, Elizabeth Soria-Castro.

  Glucose-6-phosphate dehydrogenase (G6PD) is the second rate-limiting enzyme of the pentose phosphate pathway. This enzyme is present in the cytoplasm of all mammalian cells, and its activity is essential for an adequate functioning of the antioxidant system and for the response of innate immunity. It is responsible for the production of nicotinamide adenine dinucleotide phosphate (NADPH), the first redox equivalent, in the pentose phosphate pathway. Viral infections such as SARS-CoV-2 may induce the Warburg effect with an increase in anaerobic glycolysis and production of lactate. This condition ensures the success of viral replication and production of the virion. Therefore, the activity of G6PD may be increased in COVID-19 patients raising the level of the NADPH, which is needed for the enzymatic and non-enzymatic antioxidant systems that counteract the oxidative stress caused by the cytokine storm. G6PD deficiency affects approximately 350-400 million people worldwide; therefore, it is one of the most prevalent diseases related to enzymatic deficiency worldwide. In G6PD-deficient patients exposed to SARS-CoV-2, the amount of NADPH is reduced, increasing the susceptibility for viral infection. There is loss of the redox homeostasis in them, resulting in severe pneumonia and fatal outcomes.

Keywords:  COVID-19; Glucose-6-phosphate dehydrogenase; SARS-CoV-2; Warburg effect; pentose phosphate pathway; redox homeostasis

DOI:  https://doi.org/10.3390/cells11131982
Neurotox Res. 2022 Jul 04.

Pesticides Exposure-Induced Changes in Brain Metabolome: Implications in the Pathogenesis of Neurodegenerative Disorders.

Joel Arvin Rodrigues, Rekha K Narasimhamurthy, Manjunath B Joshi, Herman Sunil Dsouza, Kamalesh Dattaram Mumbrekar.

  Pesticides have been used in agriculture, public health programs, and pharmaceuticals for many decades. Though pesticides primarily target pests by affecting their nervous system and causing other lethal effects, these chemical entities also exert toxic effects in inadvertently exposed humans through inhalation or ingestion. Mounting pieces of evidence from cellular, animal, and clinical studies indicate that pesticide-exposed models display metabolite alterations of pathways involved in neurodegenerative diseases. Hence, identifying common key metabolites/metabolic pathways between pesticide-induced metabolic reprogramming and neurodegenerative diseases is necessary to understand the etiology of pesticides in the rise of neurodegenerative disorders. The present review provides an overview of specific metabolic pathways, including tryptophan metabolism, glutathione metabolism, dopamine metabolism, energy metabolism, mitochondrial dysfunction, fatty acids, and lipid metabolism that are specifically altered in response to pesticides. Furthermore, we discuss how these metabolite alterations are linked to the pathogenesis of neurodegenerative diseases and to identify novel biomarkers for targeted therapeutic approaches.

Keywords:  Brain; Metabolites; Neurodegenerative disorders; Neurotoxicity; Organophosphate; Pesticides

DOI:  https://doi.org/10.1007/s12640-022-00534-2
Nutrients. 2022 Jun 29. pii: 2721. [Epub ahead of print]14(13):

Octanoic Acid-Enrichment Diet Improves Endurance Capacity and Reprograms Mitochondrial Biogenesis in Skeletal Muscle of Mice.

Anouk Charlot, Lucas Morel, Anthony Bringolf, Isabelle Georg, Anne-Laure Charles, Fabienne Goupilleau, Bernard Geny, Joffrey Zoll.

   BACKGROUND: Medium Chain Fatty Acids (MCFAs) are a dietary supplement that exhibit interesting properties, due to their smaller molecular size. The acute consumption of MCFAs is expected to enhance exercise performance. However, the short-term effects of MCFAs on endurance performance remains poorly understood. The aim of our study is to evaluate the octanoic acid (C8)-rich diet effect on endurance capacity, and to explore their molecular and cellular effects.
METHODS: C57BL/6J mice were fed with a chow diet (Control group) or an octanoic acid-rich diet (C8 diet) for 6 weeks. Spontaneous activity, submaximal and maximal exercise tests were carried out to characterize the exercise capacities of the mice. Beta-oxidation and mitochondrial biogenesis pathways were explored in skeletal muscle by RT-qPCR, Western Blot (Quadriceps) and histochemical staining (Gastrocnemius).
RESULTS: Mice fed with a C8-rich diet presented a higher spontaneous activity (p < 0.05) and endurance capacities (p < 0.05) than the control, but no effect on maximal effort was observed. They also presented changes in the skeletal muscle metabolic phenotype, with a higher number of the oxidative fibers, rich in mitochondria. At the molecular level, the C8-diet induced an AMPK activation (p < 0.05), associated with a significant increase in PGC1a and CS gene expression and protein levels.
CONCLUSION: Our study provided evidence that C8-enrichment as a food supplementation improves endurance capacities and activates mitochondrial biogenesis pathways leading to higher skeletal muscle oxidative capacities.

Keywords:  endurance; medium chain fatty acid; mitochondrial biogenesis; octanoic acid; skeletal muscle

DOI:  https://doi.org/10.3390/nu14132721
Int J Obes (Lond). 2022 Jul 06.

Modulation of adipose inflammation by cellular retinoic acid-binding protein 1.

Chin-Wen Wei, Jennifer Nhieu, Yu-Lung Lin, Li-Na Wei.

OBJECTIVES: Obesity, a metabolic syndrome, is known to be related to inflammation, especially adipose tissue inflammation. Cellular interactions within the expanded white adipose tissue (WAT) in obesity contribute to inflammation and studies have suggested that inflammation is triggered by inflamed adipocytes that recruit M1 macrophages into WAT. What causes accumulation of unhealthy adipocytes is an important topic of investigation. This study aims to understand the action of Cellular Retinoic Acid Binding Protein 1 (CRABP1) in WAT inflammation.
METHODS: Eight weeks-old wild type (WT) and Crabp1 knockout (CKO) mice were fed with a normal diet (ND) or high-fat diet (HFD) for 8 weeks. Body weight and food intake were monitored. WATs and serum were collected for cellular and molecular analyses to determine affected signaling pathways. In cell culture studies, primary adipocyte differentiation and bone marrow-derived macrophages (BMDM) were used to examine adipocytes' effects, mediated by CRABP1, in macrophage polarization. The 3T3L1-adipocyte was used to validate relevant signaling pathways.
RESULTS: CKO mice developed an obese phenotype, more severely under high-fat diet (HFD) feeding. Further, CKO's WAT exhibited a more severe inflammatory state as compared to wild type (WT) WAT, with a significantly expanded M1-like macrophage population. However, this was not caused by intrinsic defects of CKO macrophages. Rather, CKO adipocytes produced a significantly reduced level of adiponectin and had significantly lowered mitochondrial DNA content. CKO adipocyte-conditioned medium, compared to WT control, inhibited M2-like (CD206+) macrophage polarization. Mechanistically, defects in CKO adipocytes involved the ERK1/2 signaling pathway that could be modulated by CRABP1.
CONCLUSIONS: This study shows that CRABP1 plays a protective role against HFD-induced WAT inflammation through, in part, its regulation of adiponectin production and mitochondrial homeostasis in adipocytes, thereby modulating macrophage polarization in WAT to control its inflammatory potential.

DOI: https://doi.org/10.1038/s41366-022-01175-3
J Gen Physiol. 2022 Sep 05. pii: e202113071. [Epub ahead of print]154(9):

Specific ATPases drive compartmentalized glycogen utilization in rat skeletal muscle.

Joachim Nielsen, Peter Dubillot, Marie-Louise H Stausholm, Niels Ørtenblad.

Glycogen is a key energy substrate in excitable tissue, including in skeletal muscle fibers where it also contributes to local energy production. Transmission electron microscopy imaging has revealed the existence of a heterogenic subcellular distribution of three distinct glycogen pools in skeletal muscle, which are thought to reflect the requirements for local energy stores at the subcellular level. Here, we show that the three main energy-consuming ATPases in skeletal muscles (Ca2+, Na+,K+, and myosin ATPases) utilize different local pools of glycogen. These results clearly demonstrate compartmentalized glycogen metabolism and emphasize that spatially distinct pools of glycogen particles act as energy substrate for separated energy requiring processes, suggesting a new model for understanding glycogen metabolism in working muscles, muscle fatigue, and metabolic disorders. These observations suggest that the distinct glycogen pools can regulate the functional state of mammalian muscle cells and have important implications for the understanding of how the balance between ATP utilization and ATP production is regulated at the cellular level in general and in skeletal muscle fibers in particular.

DOI: https://doi.org/10.1085/jgp.202113071
Biochem Biophys Res Commun. 2022 Jun 28. pii: S0006-291X(22)00952-4. [Epub ahead of print]621 1-7

Mitochondrial GCN5L1 regulates cytosolic redox state and hepatic gluconeogenesis via glycerol phosphate shuttle GPD2.

Jiahui Meng, Chunyu Zhang, Danni Wang, Lu Zhu, Lingdi Wang.

  Hepatic gluconeogenesis is crucial for maintaining blood glucose during starvation, and a major contributor for hyperglycemia. Cellular redox state is related to mitochondrial biology and regulates conversion of specific metabolites to glucose. General control of amino acid synthesis 5 (GCN5) like-1 (GCN5L1) is a mitochondria-enriched protein which modulates glucose and amino acid metabolism. Here we show a new regulatory mode of GCN5L1 on gluconeogenesis using lactate and glycerol. We observed GCN5L1 deletion dramatically inhibited glucose production derived from glycerol and lactate, due to increased cytosolic redox state. The underlying mechanism is that GCN5L1 directly binds to the key component of mitochondrial shuttle glycerol phosphate dehydrogenase 2 (GPD2) and modulates its activity. These results have significant implications for understanding the physiological role and regulatory mechanism of mitochondrial shuttle in diabetes development and provide a novel therapeutic potential for diabetes.

Keywords:  Cytosolic redox state; GCN5L1; Gluconeogenesis; Glycerol-3-phosphate dehydrogenase 2; Mitochondrial redox state

DOI:  https://doi.org/10.1016/j.bbrc.2022.06.092
Cancers (Basel). 2022 Jun 28. pii: 3164. [Epub ahead of print]14(13):

The Novel Immune Checkpoint GPR56 Is Expressed on Tumor-Infiltrating Lymphocytes and Selectively Upregulated upon TCR Signaling.

Vrouyr Bilemjian, Martijn R Vlaming, Jimena Álvarez Freile, Gerwin Huls, Marco De Bruyn, Edwin Bremer.

  High levels of tumor-infiltrating lymphocytes (TILs) in the tumor microenvironment (TME) are associated with a survival benefit in various cancer types and the targeted (re)activation of TILs is an attractive therapeutic anti-cancer approach that yields curative responses. However, current T cell targeting strategies directed at known immune checkpoints have not increased objective response rates for all cancer types, including for epithelial ovarian cancer (EOC). For this reason, the identification of new immune checkpoints that regulate T cell immunity remains of great interest. One yet largely uninvestigated checkpoint of potential interest is the G protein-coupled receptor 56 (GPR56), which belongs to the adhesion GPCR family. GPR56 was originally reported to function in cerebral cortical development and in anti-depressant response, but also in cancer. Recently, GPR56 was identified as an inhibitory receptor expressed on human NK cells that by cis-interaction with the tetraspanin CD81 attenuated the cytotoxic activity of NK cells. This NK cell checkpoint could be blocked by an GPR56 antibody, leading to increased cytotoxicity. Interestingly, GPR56 expression has also been reported on cytokine producing memory CD8 T lymphocytes and may thus represent a T cell checkpoint as well. Here, GPR56 mRNA expression was characterized in the context of TILs, with GPR56 expression being detected predominantly in tumor infiltrating CD8 T cells with a cytotoxic and (pre-)exhausted phenotype. In accordance with this mRNA profile, TILs from ovarian cancer patients expressed GPR56 primarily within the effector memory and central memory T cell subsets. On T cells from healthy donors the expression was limited to effector memory and terminally differentiated T cells. Notably, GPR56 expression further increased on TILs upon T cell receptor (TCR)-mediated stimulation in co-cultures with cancer cells, whereas GPR56 expression on healthy primary human T cells did not. Further, the ectopic expression of GPR56 significantly reduced the migration of GPR56-positive T cells. Taken together, GPR56 is a potential immune-checkpoint in EOC found on (pre-)exhausted CD8 TILs that may regulate migratory behavior.

Keywords:  GPR56; cancer immunotherapy; immune checkpoint; tumor-infiltrated lymphocytes (TIL)

DOI:  https://doi.org/10.3390/cancers14133164
Genes Dis. 2022 May;9(3): 717-730

Targeting UDP-α-d-glucose 6-dehydrogenase alters the CNS tumor immune microenvironment and inhibits glioblastoma growth.

Daqian Zhan, Fatih Yalcin, Ding Ma, Yi Fu, Shuang Wei, Bachchu Lal, Yunqing Li, Omar Dzaye, John Laterra, Mingyao Ying, Hernando Lopez-Bertoni, Shuli Xia.

  Glioblastoma (GBM, WHO grade IV glioma) is the most common and lethal malignant brain tumor in adults with a dismal prognosis. The extracellular matrix (ECM) supports GBM progression by promoting tumor cell proliferation, migration, and immune escape. Uridine diphosphate (UDP)-glucose 6-dehydrogenase (UGDH) is the rate-limiting enzyme that catalyzes the biosynthesis of glycosaminoglycans that are the principal component of the CNS ECM. We investigated how targeting UGDH in GBM influences the GBM immune microenvironment, including tumor-associated microglia/macrophages (TAMs) and T cells. TAMs are the main immune effector cells in GBM and can directly target tumor cells if properly activated. In co-cultures of GBM cells and human primary macrophages, UGDH knockdown in GBM cells promoted macrophage phagocytosis and M1-like polarization. In orthotropic human GBM xenografts and syngeneic mouse glioma models, targeting UGDH decreased ECM deposition, increased TAM phagocytosis marker expression, reduced M2-like TAMs and inhibited tumor growth. UGDH knockdown in GBM cells also promoted cytotoxic T cell infiltration and activation in orthotopic syngeneic mouse glioma models. The potent and in-human-use small molecule GAG synthesis inhibitor 4-methylumbelliferone (4-MU) was found to inhibit GBM cell proliferation and migration in vitro, mimic the macrophage and T-cell responses to UGDH knockdown in vitro and in vivo and inhibit growth of orthotopic murine GBM. Our study shows that UGDH supports GBM growth through multiple mechanisms and supports the development of ECM-based therapeutic strategies to simultaneously target tumor cells and their microenvironment.

Keywords:  4-MU; Extracellular matrix (ECM); Glioblastoma (GBM); Hyaluronic acid (HA); Phagocytosis; T cells; Tumor-associated microglia/macrophages (TAMs); UGDH

DOI:  https://doi.org/10.1016/j.gendis.2021.08.008
Hepatology. 2022 Jul 05.

Essential lipid autacoids rewire mitochondrial energy efficiency in metabolic dysfunction-associated fatty liver disease.

Cristina López-Vicario, David Sebastián, Mireia Casulleras, Marta Duran-Güell, Roger Flores-Costa, Ferran Aguilar, Juan José Lozano, Ingrid W Zhang, Esther Titos, Jing X Kang, Antonio Zorzano, Makoto Arita, Joan Clària.

BACKGROUND&AIM: Injury to hepatocyte mitochondria is common in metabolic dysfunction-associated fatty liver disease. Here, we investigated whether changes in the content of essential fatty acid-derived lipid autacoids affect hepatocyte mitochondrial bioenergetics and metabolic efficiency.
APPROACH&RESULTS: The study was performed in transgenic mice for the fat-1 gene, which allows the endogenous replacement of the membrane omega-6-polyunsaturated fatty acid (PUFA) composition by omega-3-PUFA. Transmission electron microscopy revealed that hepatocyte mitochondria of fat-1 mice had more abundant intact cristae and higher mitochondrial aspect ratio. Fat-1 mice had increased expression of oxidative phosphorylation complexes I and II and translocases of both inner (TIM44) and outer (TOM20) mitochondrial membranes. Fat-1 mice also showed increased mitofusin-2 and reduced DRP1 phosphorylation, which mediate mitochondrial fusion and fission, respectively. Mitochondria of fat-1 mice exhibited enhanced oxygen consumption rate, fatty acid β-oxidation and energy substrate utilization as determined by high-resolution respirometry, [1-14 C]-oleate oxidation and NADH/FADH2 production, respectively. Untargeted lipidomics identified a rich hepatic omega-3-PUFA composition and a specific docosahexaenoic acid (DHA)-enriched lipid fingerprint in fat-1 mice. Targeted lipidomics uncovered a higher content of DHA-derived lipid autacoids, namely resolvin D1 and maresin 1, which rescued hepatocytes from TNFα-induced mitochondrial dysfunction, unblocked the tricarboxylic acid cycle flux and metabolic utilization of long-chain acyl-carnitines, amino acids and carbohydrates. Importantly, fat-1 mice were protected against mitochondrial injury induced by obesogenic and fibrogenic insults.
CONCLUSION: Our data uncover the importance of a lipid membrane composition rich in DHA and its lipid autacoid derivatives to have optimal hepatic mitochondrial and metabolic efficiency.

DOI: https://doi.org/10.1002/hep.32647
Metabolism. 2022 Jun 30. pii: S0026-0495(22)00123-8. [Epub ahead of print] 155245

Compromised glycolysis contributes to foot process fusion of podocytes in diabetic kidney disease: Role of ornithine catabolism.

Qiang Luo, Wei Liang, Zongwei Zhang, Zijing Zhu, Zhaowei Chen, Jijia Hu, Keju Yang, Qingjia Chi, Guohua Ding.

   INTRODUCTION: Compromised glycolysis in podocytes contributes to the initiation of diabetic kidney disease (DKD). Podocyte injury is characterized by cytoskeletal remodeling and foot process fusion. Compromised glycolysis in diabetes likely leads to switch of energy supply in podocyte. However, the underlying mechanism by which disturbed energy supply in podocytes affects the cytoskeletal structure of podocytes remains unclear.
METHODS: Metabolomic and transcriptomic analyses were performed on the glomeruli of db/db mice to examine the catabolism of glucose, fatty, and amino acids. Ornithine catabolism was targeted in db/db and podocyte-specific pyruvate kinase M2 knockout (PKM2-podoKO) mice. In vitro, expression of ornithine decarboxylase (ODC1) was modulated to investigate the effect of ornithine catabolism on mammalian/mechanistic target of rapamycin (mTOR) signaling and cytoskeletal remodeling in cultured podocytes.
RESULTS: Multi-omic analyses of the glomeruli revealed that ornithine metabolism was enhanced in db/db mice compared with that in db/m mice under compromised glycolytic conditions. Additionally, ornithine catabolism was exaggerated in podocytes of diabetic PKM2-podoKO mice compared with that in diabetic PKM2flox/flox mice. In vivo, difluoromethylornithine (DFMO, inhibitor of ODC1) administration reduced urinary albumin excretion and alleviated podocyte foot process fusion in db/db mice. In vitro, 2-deoxy-d-glucose (2-DG) exposure induced mTOR signaling activation and cytoskeletal remodeling in podocytes, which was alleviated by ODC1-knockdown. Mechanistically, a small GTPase Ras homolog enriched in the brain (Rheb), a sensor of mTOR signaling, was activated by exposure to putrescine, a metabolic product of ornithine catabolism.
CONCLUSION: These findings demonstrate that compromised glycolysis in podocytes under diabetic conditions enhances ornithine catabolism. The metabolites of ornithine catabolism contribute to mTOR signaling activation via Rheb and cytoskeletal remodeling in podocytes in DKD.

Keywords:  Cytoskeleton; Diabetic kidney disease; Ornithine catabolism; PKM2; Podocytes; mTOR

DOI:  https://doi.org/10.1016/j.metabol.2022.155245
J Transl Med. 2022 Jul 06. 20(1): 302

Spatial transcriptomics atlas reveals the crosstalk between cancer-associated fibroblasts and tumor microenvironment components in colorectal cancer.

Zhiwei Peng, Manping Ye, Huiming Ding, Zhenyou Feng, Kongwang Hu.

   BACKGROUND: The tumor-promoting role of tumor microenvironment (TME) in colorectal cancer has been widely investigated in cancer biology. Cancer-associated fibroblasts (CAFs), as the main stromal component in TME, play an important role in promoting tumor progression and metastasis. Hence, we explored the crosstalk between CAFs and microenvironment in the pathogenesis of colorectal cancer in order to provide basis for precision therapy.
METHODS: We integrated spatial transcriptomics (ST) and bulk-RNA sequencing datasets to explore the functions of CAFs in the microenvironment of CRC. In detail, single sample gene set enrichment analysis (ssGSEA), gene set variation analysis (GSVA), pseudotime analysis and cell proportion analysis were utilized to identify the cell types and functions of each cell cluster. Immunofluorescence and immunohistochemistry were applied to confirm the results based on bioinformatics analysis.
RESULTS: We profiled the tumor heterogeneity landscape and identified two distinct types of CAFs, which myo-cancer-associated fibroblasts (mCAFs) is associated with myofibroblast-like cells and inflammatory-cancer-associated fibroblasts (iCAFs) is related to immune inflammation. When we carried out functional analysis of two types of CAFs, we uncovered an extensive crosstalk between iCAFs and stromal components in TME to promote tumor progression and metastasis. Noticeable, some anti-tumor immune cells such as NK cells, monocytes were significantly reduced in iCAFs-enriched cluster. Then, ssGSEA analysis results showed that iCAFs were related to EMT, lipid metabolism and bile acid metabolism etc. Besides, when we explored the relationship of chemotherapy and microenvironment, we detected that iCAFs influenced immunosuppressive cells and lipid metabolism reprogramming in patient who underwent chemotherapy. Additionally, we identified the clinical role of iCAFs through a public database and confirmed it were related to poor prognosis.
CONCLUSIONS: In summary, we identified two types of CAFs using integrated data and explored their functional significance in TME. This in-depth understanding of CAFs in microenvironment may help us to elucidate its cancer-promoting functions and offer hints for therapeutic studies.

Keywords:  Cancer-associated fibroblasts; Colorectal cancer; Spatial transcriptomics; Tumor microenvironment

DOI:  https://doi.org/10.1186/s12967-022-03510-8
Int J Mol Sci. 2022 Jun 29. pii: 7255. [Epub ahead of print]23(13):

Chronic Hyperglycaemia Inhibits Tricarboxylic Acid Cycle in Rat Cardiomyoblasts Overexpressing Glucose Transporter Type 4.

Bernd Stratmann, Britta Eggers, Yvonne Mattern, Tayana Silva de Carvalho, Katrin Marcus, Diethelm Tschoepe.

  An oversupply of nutrients with a loss of metabolic flexibility and subsequent cardiac dysfunction are hallmarks of diabetic cardiomyopathy. Even if excess substrate is offered, the heart suffers energy depletion as metabolic fluxes are diminished. To study the effects of a high glucose supply, a stably glucose transporter type 4 (GLUT4)-overexpressing cell line presenting an onset of diabetic cardiomyopathy-like phenotype was established. Long-term hyperglycaemia effects were analysed. Rat cardiomyoblasts overexpressing GLUT4 (H9C2KE2) were cultured under normo- and hyperglycaemic conditions for long-term. Expression profiles of several proteins were compared to non-transfected H9C2 cells (H9C2) using RT-qPCR, proteomics-based analysis, or Western blotting. GLUT4 surface analysis, glucose uptake, and cell morphology changes as well as apoptosis/necrosis measurements were performed using flow cytometry. Additionally, brain natriuretic peptide (BNP) levels, reactive oxygen species (ROS) formation, glucose consumption, and lactate production were quantified. Long-term hyperglycaemia in H9C2KE2 cells induced increased GLUT4 presence on the cell surface and was associated with exaggerated glucose influx and lactate production. On the metabolic level, hyperglycaemia affected the tricarboxylic acid (TCA) cycle with accumulation of fumarate. This was associated with increased BNP-levels, oxidative stress, and lower antioxidant response, resulting in pronounced apoptosis and necrosis. Chronic glucose overload in cardiomyoblasts induced by GLUT4 overexpression and hyperglycaemia resulted in metabolically stimulated proteome profile changes and metabolic alterations on the TCA level.

Keywords:  TCA cycle; apoptosis; diabetic cardiomyopathy; fumarate; metabolic starvation

DOI:  https://doi.org/10.3390/ijms23137255
Int J Mol Sci. 2022 Jul 05. pii: 7467. [Epub ahead of print]23(13):

New Avenues of Heme Synthesis Regulation.

Amy E Medlock, Harry A Dailey.

  During erythropoiesis, there is an enormous demand for the synthesis of the essential cofactor of hemoglobin, heme. Heme is synthesized de novo via an eight enzyme-catalyzed pathway within each developing erythroid cell. A large body of data exists to explain the transcriptional regulation of the heme biosynthesis enzymes, but until recently much less was known about alternate forms of regulation that would allow the massive production of heme without depleting cellular metabolites. Herein, we review new studies focused on the regulation of heme synthesis via carbon flux for porphyrin synthesis to post-translations modifications (PTMs) that regulate individual enzymes. These PTMs include cofactor regulation, phosphorylation, succinylation, and glutathionylation. Additionally discussed is the role of the immunometabolite itaconate and its connection to heme synthesis and the anemia of chronic disease. These recent studies provide new avenues to regulate heme synthesis for the treatment of diseases including anemias and porphyrias.

Keywords:  aminolevulinic acid synthase; ferrochelatase; heme; iron; itaconate; porphyrin; posttranslational modification

DOI:  https://doi.org/10.3390/ijms23137467
Sci Rep. 2022 Jul 05. 12(1): 11346

Targeted therapy of pyrrolo[2,3-d]pyrimidine antifolates in a syngeneic mouse model of high grade serous ovarian cancer and the impact on the tumor microenvironment.

Adrianne Wallace-Povirk, Lisa Rubinsak, Agnes Malysa, Sijana H Dzinic, Manasa Ravindra, Mathew Schneider, James Glassbrook, Carrie O'Connor, Zhanjun Hou, Seongho Kim, Jessica Back, Lisa Polin, Robert T Morris, Aleem Gangjee, Heather Gibson, Larry H Matherly.

Novel therapies are urgently needed for epithelial ovarian cancer (EOC), the most lethal gynecologic malignancy. In addition, therapies that target unique vulnerabilities in the tumor microenvironment (TME) of EOC have largely been unrealized. One strategy to achieve selective drug delivery for EOC therapy involves use of targeted antifolates via their uptake by folate receptor (FR) proteins, resulting in inhibition of essential one-carbon (C1) metabolic pathways. FRα is highly expressed in EOCs, along with the proton-coupled folate transporter (PCFT); FRβ is expressed on activated macrophages, a major infiltrating immune population in EOC. Thus, there is great potential for targeting both the tumor and the TME with agents delivered via selective transport by FRs and PCFT. In this report, we investigated the therapeutic potential of a novel cytosolic C1 6-substituted pyrrolo[2,3-d]pyrimidine inhibitor AGF94, with selectivity for uptake by FRs and PCFT and inhibition of de novo purine nucleotide biosynthesis, against a syngeneic model of ovarian cancer (BR-Luc) which recapitulates high-grade serous ovarian cancer in patients. In vitro activity of AGF94 was extended in vivo against orthotopic BR-Luc tumors. With late-stage subcutaneous BR-Luc xenografts, AGF94 treatment resulted in substantial anti-tumor efficacy, accompanied by significantly decreased M2-like FRβ-expressing macrophages and increased CD3+ T cells, whereas CD4+ and CD8+ T cells were unaffected. Our studies demonstrate potent anti-tumor efficacy of AGF94 in the therapy of EOC in the context of an intact immune system, and provide a framework for targeting the immunosuppressive TME as an essential component of therapy.

DOI: https://doi.org/10.1038/s41598-022-14788-5