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1.
Amino Acid Metabolism in Cancer Drug Resistance.
Yoo, HC, Han, JM
Cells. 2022;(1)
Abstract
Despite the numerous investigations on resistance mechanisms, drug resistance in cancer therapies still limits favorable outcomes in cancer patients. The complexities of the inherent characteristics of tumors, such as tumor heterogeneity and the complicated interaction within the tumor microenvironment, still hinder efforts to overcome drug resistance in cancer cells, requiring innovative approaches. In this review, we describe recent studies offering evidence for the essential roles of amino acid metabolism in driving drug resistance in cancer cells. Amino acids support cancer cells in counteracting therapies by maintaining redox homeostasis, sustaining biosynthetic processes, regulating epigenetic modification, and providing metabolic intermediates for energy generation. In addition, amino acid metabolism impacts anticancer immune responses, creating an immunosuppressive or immunoeffective microenvironment. A comprehensive understanding of amino acid metabolism as it relates to therapeutic resistance mechanisms will improve anticancer therapeutic strategies.
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2.
Altered amino acid profile in patients with SARS-CoV-2 infection.
Rees, CA, Rostad, CA, Mantus, G, Anderson, EJ, Chahroudi, A, Jaggi, P, Wrammert, J, Ochoa, JB, Ochoa, A, Basu, RK, et al
Proceedings of the National Academy of Sciences of the United States of America. 2021;(25)
Abstract
Low plasma arginine bioavailability has been implicated in endothelial dysfunction and immune dysregulation. The role of arginine in COVID-19 is unknown, but could contribute to cellular damage if low. Our objective was to determine arginine bioavailability in adults and children with COVID-19 vs. healthy controls. We hypothesized that arginine bioavailability would be low in patients with COVID-19 and multisystem inflammatory syndrome in children (MIS-C). We conducted a prospective observational study of three patient cohorts; arginine bioavailability was determined in asymptomatic healthy controls, adults hospitalized with COVID-19, and hospitalized children/adolescents <21 y old with COVID-19, MIS-C, or asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection identified on admission screen. Mean patient plasma amino acids were compared to controls using the Student's t test. Arginine-to-ornithine ratio, a biomarker of arginase activity, and global arginine bioavailability ratio (GABR, arginine/[ornithine+citrulline]) were assessed in all three groups. A total of 80 patients were included (28 controls, 32 adults with COVID-19, and 20 pediatric patients with COVID-19/MIS-C). Mean plasma arginine and arginine bioavailability ratios were lower among adult and pediatric patients with COVID-19/MIS-C compared to controls. There was no difference between arginine bioavailability in children with COVID-19 vs. MIS-C. Adults and children with COVID-19 and MIS-C in our cohort had low arginine bioavailability compared to healthy adult controls. This may contribute to immune dysregulation and endothelial dysfunction in COVID-19. Low arginine-to-ornithine ratio in patients with COVID-19 or MIS-C suggests an elevation of arginase activity. Further study is merited to explore the role of arginine dysregulation in COVID-19.
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3.
Coordination of the Uptake and Metabolism of Amino Acids in Mycobacterium tuberculosis-Infected Macrophages.
Jiang, Q, Shi, L
Frontiers in immunology. 2021;:711462
Abstract
Macrophage polarization to the M1-like phenotype, which is critical for the pro-inflammatory and antimicrobial responses of macrophages against intracellular pathogens, is associated with metabolic reprogramming to the Warburg effect and a high output of NO from increased expression of NOS2. However, there is limited understanding about the uptake and metabolism of other amino acids during M1 polarization. Based on functional analysis of a group of upregulated transporters and enzymes involved in the uptake and/or metabolism of amino acids in Mycobacterium tuberculosis-infected macrophages, plus studies of immune cell activation, we postulate a coherent scheme for amino acid uptake and metabolism during macrophage polarization to the M1-like phenotype. We describe potential mechanisms that the increased arginine metabolism by NOS2 is metabolically coupled with system L transporters LAT1 and LAT2 for the uptake of neutral amino acids, including those that drive mTORC1 signaling toward the M1-like phenotype. We also discuss the underappreciated pleiotropic roles of glutamine metabolism in the metabolic reprogramming of M1-like macrophages. Collectively, our analyses argue that a coordinated amino acid uptake and metabolism constitutes an integral component of the broad metabolic scheme required for macrophage polarization to M1-like phenotype against M. tuberculosis infection. This idea could stimulate future experimental efforts to elucidate the metabolic map of macrophage activation for the development of anti-tuberculosis therapies.
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4.
Fueling T-cell Antitumor Immunity: Amino Acid Metabolism Revisited.
Han, C, Ge, M, Ho, PC, Zhang, L
Cancer immunology research. 2021;(12):1373-1382
Abstract
T cells are the key players in eliminating malignant tumors. Adoptive transfer of tumor antigen-specific T cells and immune checkpoint blockade has yielded durable antitumor responses in the clinic, but not all patients respond initially and some that do respond eventually have tumor progression. Thus, new approaches to enhance the utility of immunotherapy are needed. T-cell activation and differentiation status are tightly controlled at the transcriptional, epigenetic, and metabolic levels. Amino acids are involved in multiple steps of T-cell antitumor immunity, including T-cell activation, proliferation, effector function, memory formation as well as functional exhaustion. In this review, we briefly discuss how amino acid metabolism is linked to T-cell fate decisions and summarize how amino acid deprivation or accumulation of certain amino acid metabolites within the tumor microenvironment diminishes T-cell functionality. Furthermore, we discuss potential strategies for immunotherapy via modulating amino acid metabolism either in T cells intrinsically or extrinsically to achieve therapeutic efficacy.
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5.
Supplementation with a Natural Source of Amino Acids, Sil-Q1 (Silk Peptide), Enhances Natural Killer Cell Activity: A Redesigned Clinical Trial with a Reduced Supplementation Dose and Minimized Seasonal Effects in a Larger Population.
Cho, JM, Yoo, D, Lee, JY, Oh, MS, Ha, KC, Baek, HI, Lee, SM, Lee, JH, Yoo, HJ
Nutrients. 2021;(9)
Abstract
The aim of this study was to re-validate the changes in natural killer (NK) cell cytotoxicity and cytokines related to T cells after Sil-Q1 (SQ; silk peptide) supplementation in a larger pool of Korean adults with minimized daily dose of SQ and controlling seasonal influence compared to the previous study. A total of 130 subjects were randomly assigned (1:1) to consume either 7.5 g of SQ or placebo for 8 weeks. NK cell cytotoxicity and cytokines were measured at T0 (baseline) and T8 (follow-up). Comparing the NK cell cytotoxicity values at T0 and T8 within each group, the cytotoxicity at all effector cell (E) to target cell (T) ratios of 10:1, 5:1, 2.5:1, and 1.25:1 was significantly increased in the SQ group at T8. Additionally, significant differences in the changed value (Δ, subtract baseline values from follow-up values) comparison between the groups at E:T = 10:1, 5:1, and 2.5:1 were found. As a secondary endpoint, the interleukin (IL)-12 level in the SQ group was significantly increased for 8 weeks, and Δ IL-12 in the SQ group was greater than in the placebo group. In conclusion, the present study showed considerable practical implications of SQ supplementation. Thus, SQ is an effective and safe functional food supplement for enhancing immune function.
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6.
Artificial Polymers made of α-amino Acids - Poly(Amino Acid)s, Pseudo-Poly(Amino Acid)s, Poly(Depsipeptide)s, and Pseudo-Proteins.
Zavradashvili, N, Puiggali, J, Katsarava, R
Current pharmaceutical design. 2020;(5):566-593
Abstract
Degradable polymers (DPs) - "green materials" of the future, have an innumerable use in biomedicine, particularly in the fields of tissue engineering and drug delivery. Among these kind of materials naturally occurring polymers - proteins which constituted one of the most important "bricks of life" - α-amino acids (AAs) are highly suitable. A wide biomedical applicability of proteins is due to special properties such as a high affinity with tissues and releasing AAs upon biodegradation that means a nutritive potential for cells. Along with these positive characteristics proteins as biomedical materials they have some shortcomings, such as batch-to-batch variation, risk of disease transmission, and immune rejection. The last limitation is connected with the molecular architecture of proteins. Furthermore, the content of only peptide bonds in protein molecules significantly restricts their material properties. Artificial polymers with the composition of AAs are by far more promising as degradable biomaterials since they are free from the limitations of proteins retaining at the same time their positive features - a high tissue compatibility and nutritive potential. The present review deals with a brief description of different families of AA-based artificial polymers, such as poly(amino acid)s, pseudo-poly(amino acid)s, polydepsipeptides, and pseudo-proteins - relatively new and broad family of artificial AA-based DPs. Most of these polymers have a different macromolecular architecture than proteins and contain various types of chemical links along with NH-CO bonds that substantially expands properties of materials destined for sophisticated biomedical applications.
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7.
The significant role of amino acids during pregnancy: nutritional support.
Manta-Vogli, PD, Schulpis, KH, Dotsikas, Y, Loukas, YL
The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians. 2020;(2):334-340
Abstract
Background: Pregnancy is characterized by a complexity of metabolic processes that may impact fetal development and infant health outcome. Normal fetal growth and development depend on a continuous supply of nutrients via the placenta. The placenta transports, utilizes, produces, and interconverts amino acids (AAs).Findings: Concentrations of both nonessential and essential AAs in maternal plasma decrease in early pregnancy and persist at low concentrations throughout. The decline is greatest for the glucogenic AAs and AAs of the urea cycle. Additionally, there is a large placental utilization of the branched-chain AAs, some of which are transaminated to alpha ketoacids and contribute to placental ammonia production. Both nonessential and essential AAs regulate key metabolic pathways to improve health, survival, growth, development, lactation, and reproduction of organisms. Some of the nonessential AAs (e.g. glutamine, glutamate, and arginine) play also important roles in regulating gene expression, cell signaling, antioxidant responses, immunity, and neurological function.Conclusions: Nutritional support during pregnancy is of great interest focusing not only to common pregnancies but also to those with low socioeconomic status, vegan-vegetarian groups, and pregnant women with metabolic disorders, the most known maternal phenylketonuria. The latter is of great interest because phenylalanine must be within the recommended range throughout pregnancy in addition to other nutrients such as vitamin B12, folate, etc. Loss of the adherence to this specific diet results in congenital malformations of the fetus. In addition to the routine laboratory test, quantitation of plasma AAs may be necessary throughout pregnancy.
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8.
Free Amino Acids in Human Milk: A Potential Role for Glutamine and Glutamate in the Protection Against Neonatal Allergies and Infections.
van Sadelhoff, JHJ, Wiertsema, SP, Garssen, J, Hogenkamp, A
Frontiers in immunology. 2020;:1007
Abstract
Breastfeeding is indicated to support neonatal immune development and to protect against neonatal infections and allergies. Human milk composition is widely studied in relation to these unique abilities, which has led to the identification of various immunomodulating components in human milk, including various bioactive proteins. In addition to proteins, human milk contains free amino acids (FAAs), which have not been well-studied. Of those, the FAAs glutamate and glutamine are by far the most abundant. Levels of these FAAs in human milk sharply increase during the first months of lactation, in contrast to most other FAAs. These unique dynamics are globally consistent, suggesting that their levels in human milk are tightly regulated throughout lactation and, consequently, that they might have specific roles in the developing neonate. Interestingly, free glutamine and glutamate are reported to exhibit immunomodulating capacities, indicating that these FAAs could contribute to neonatal immune development and to the unique protective effects of breastfeeding. This review describes the current understanding of the FAA composition in human milk. Moreover, it provides an overview of the effects of free glutamine and glutamate on immune parameters relevant for allergic sensitization and infections in early life. The data reviewed provide rationale to study the role of free glutamine and glutamate in human milk in the protection against neonatal allergies and infections.
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9.
A Pilot Study of Amino Acids in Unresectable Non-Small-Cell Lung Cancer Patients During Chemotherapy: A Randomized Serial N-of-1 Trials Design.
Liu, L, Zhang, Y, Wei, J, Chen, Z, Yu, J
Nutrition and cancer. 2019;(3):399-408
Abstract
The aim of this study was to evaluate the effect of amino acids (AAs) on immune function and inflammation level in patients with NSCLC receiving chemotherapy. We conducted a series of randomized, multiple-crossover, double-blind, placebo-controlled N-of-1 trials comparing AAs with isocaloric glucose in unresectable NSCLC patients and combined the individual results using Bayesian statistical modeling. 25 patients completed two cycles of chemotherapy. The baseline total blood albumin (ALB) level in all patients was 28 ± 3.3 g/l, and the mean total ALB level in patients receiving AAs supplementation and isocaloric glucose was 29.2 ± 2.2 and 28.1 ± 3.7 g/l, respectively (P = 0.028). Patients' baseline C-reactive protein (CRP) level was 4 ± 1.2 mg/l, the mean total CRP level in patients receiving AAs supplementation and isocaloric glucose was 11 ± 2.8 and 13 ± 3.2 mg/l, respectively (P = 0.028). The baseline total blood CD4+ T cells level was 36 ± 7.8%. The percentage of CD4+ T cells in patients receiving AAs supplementation and isocaloric glucose was 42 ± 6.4 and 33.7 ± 17.3, respectively (P = 0.034). Our preliminary results indicated that AAs improve immune status and suppress inflammation in unresectable NSCLC patients receiving chemotherapy.
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10.
The use of amino acid-based nutritional feeds is effective in the dietary management of pediatric eosinophilic oesophagitis.
Atwal, K, Hubbard, GP, Venter, C, Stratton, RJ
Immunity, inflammation and disease. 2019;(4):292-303
Abstract
INTRODUCTION Eosinophilic oesophagitis (EoE) is an immune-mediated, chronic disease characterized by eosinophilic inflammation and esophageal dysfunction. Specific food allergens including cow's milk protein, are partially causative to disease progression, and dietary management forms three main options; the elemental diet (ED), the empirical elimination diet (EED), and the targeted elimination diet (TED). The dietary choice should be individualized, however, the European Society for Pediatric Gastroenterology, Hepatology and Nutrition guidelines recommend an ED for pediatric EoE with multiple food allergies, failure to thrive, unresponsive disease or unable to follow a highly restricted diet. The aim of this narrative review was to explore the effectiveness of the ED (using amino acid formula [AAF]), in the management of pediatric EoE. METHODS Literature searches were performed to identify eligible studies that described outcomes including eosinophil count, clinical symptoms, growth, and medications. RESULTS Overall, 10 eligible studies were found, with n = 462 patients assigned to receive AAF from a total of n = 748 (average age 6.7 years), for a duration of 4 to 8 weeks. The use of AAF reduced eosinophil levels and demonstrated remission (defined as ≤10 eosinophils per high power field) in 75%-100% of children with improvements, if not resolution, in clinical symptoms. AAF was more clinically effective than the use of the EED or TED, where remission rates were 75%-81% and 40%-69%, respectively. Few studies collected growth outcomes, however where documented these were positive for those on AAF. The long-term impacts of each diet were not thoroughly explored. CONCLUSIONS The use of AAF is a clinically effective management option for pediatric EoE, and further research is required to guide long-term management.