Summary of workshop discussions on establishing upper limits for amino acids with specific attention to available data for the essential amino acids leucine and tryptophan

Metabolomics coupled with network pharmacology study on the protective effect of Keguan-1 granules in LPS-induced acute lung injury

CONTEXT

Keguan-1 (KG-1) plays a vital role in enhancing the curative effects, improving quality of life, and reducing the development of acute lung injury (ALI).

OBJECTIVE

To unravel the protective effect and underlying mechanism of KG-1 against ALI.

MATERIALS AND METHODS

C57BL/6J mice were intratracheally instilled with lipopolysaccharide to establish the ALI model. Then, mice in the KG-1 group received a dose of 5.04 g/kg for 12 h. The levels of proinflammatory cytokines, chemokines, and pathological characteristics were determined to explore the effects of KG-1. Next, untargeted metabolomics was used to identify the differential metabolites and involved pathways for KG-1 anti-ALI. Network pharmacology was carried out to predict the putative active components and drug targets of KG-1 anti-ALI.

RESULTS

KG-1 significantly improved the levels of TNF-α (from 2295.92 ± 529.87 pg/mL to 1167.64 ± 318.91 pg/mL), IL-6 (from 4688.80 ± 481.68 pg/mL to 3604.43 ± 382.00 pg/mL), CXCL1 (from 4361.76 ± 505.73 pg/mL to 2981.04 ± 526.18 pg/mL), CXCL2 (from 5034.09 ± 809.28 pg/mL to 2980.30 ± 747.63 pg/mL), and impaired lung histological damage. Untargeted metabolomics revealed that KG-1 significantly regulated 12 different metabolites, which mainly related to lipid, amino acid, and vitamin metabolism. Network pharmacology showed that KG-1 exhibited anti-ALI effects through 17 potentially active components acting on seven putative drug targets to regulate four metabolites.

DISCUSSION AND CONCLUSIONS

This work elucidated the therapeutic effect and underlying mechanism by which KG-1 protects against ALI from the view of the metabolome, thus providing a scientific basis for the usage of KG-1.

Emerging Concepts in Nutrient Needs

Dietary reference intakes (DRIs) are quantitative, nutrient intake-based standards used for assessing the diets and specific nutrient intakes of healthy individuals and populations and for informing national nutrition policy and nutrition programs. Because nutrition needs vary by age, sex, and physiological state, DRIs are often specified for healthy subgroups within a population. Diet is known to be the leading modifiable risk factor for chronic disease, and the prevalence of chronic disease is growing in all populations globally and across all subgroups, but especially in older adults. It is known that nutrient needs can change in some chronic disease and other clinical states. Disease states and/or disease treatment can cause whole-body or tissue-specific nutrient depletion or excess, resulting in the need for altered nutrient intakes. In other cases, disease-related biochemical dysfunction can result in a requirement for a nonessential nutrient, rendering it as conditionally essential, or result in toxicity for a food component at levels usually tolerated by healthy people, as seen in inborn errors of metabolism. Here we summarize examples from a growing body of literature of disease-altering nutrient requirements, supporting the need to give more consideration to special nutrient requirements in disease states.

Sobriety and Satiety: Is NAD+ the Answer?

Nicotinamide adenine dinucleotide (NAD+) is an essential pyridine nucleotide that has garnered considerable interest in the last century due to its critical role in cellular processes associated with energy production, cellular protection against stress and longevity. Research in NAD+ has been reinvigorated by recent findings that components of NAD+ metabolism and NAD-dependent enzymes can influence major signalling processes associated with the neurobiology of addiction. These studies implicate raising intracellular NAD+ levels as a potential target for managing and treating addictive behaviour and reducing cravings and withdrawal symptoms in patients with food addiction and/or substance abuse. Since clinical studies showing the use of NAD+ for the treatment of addiction are limited, this review provides literature evidence that NAD+ can influence the neurobiology of addiction and may have benefits as an anti-addiction intervention.

An untargeted metabolomics approach to investigate the wine-processed mechanism of Scutellariae radix in acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellariae radix (SR) is one of the most popular traditional Chinese medicines (TCM). Crude SR (CSR) and wine-processed SR (WSR) are the two most common commercial specifications. According to the theories of TCM, wine-processing increases the inclination and direction of SR's actions, thereby strengthening its efficacy in clearing the upper-energizer lung damp heat. The pharmacological mechanism-related research on WSR for the treatment of lung disease is limited and needs to be expanded.

AIM OF THE STUDY

The aim of this report was to identify the relevant biological pathways by assessing changes in plasma metabolites between CSR and WSR in a lipopolysaccharide (LPS)-induced acute lung injury (ALI) model, and thus, revealed the potential mechanism of wine processing in SR.

MATERIALS AND METHODS

Rats with LPS-induced ALI were treated with CSR and WSR. The contents of inflammatory cytokines and histopathological examination were determined to explore the effects of CSR and WSR. Next, the metabolic profiling of rat plasma samples was performed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). Then, principal component analysis (PCA) were used to provide an overview for all of the groups and orthogonal partial least squares-discriminant analysis (OPLS-DA) was utilized to maximize the discrimination and present the differences in the metabolite between all of the groups.

RESULTS

WSR exhibited a more remarkable effect on improving ALI than CSR by reducing the levels of inflammatory factors, including nitric oxide (NO), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8). On the basis of UPLC-QTOF-MS technology, an unequal curative effect was revealed by nontargeting metabolomics. Sixteen biomarkers were discovered in the plasma of LPS-induced rats. Pathway analysis indicated that CSR acted on ALI by regulating the abnormal sphingolipid metabolism pathways; however, an WSR-mediated cure of ALI was linked primarily to reversing the abnormality of retinol metabolism pathways and tryptophan metabolism pathways.

CONCLUSIONS

This report examined the underlying wine-processing mechanism of SR from the perspective of plasma metabolites. In addition, this work provided a novel and valuable insight into interpretation of the processing mechanisms of TCM in a holistic way.

NAD(+) metabolism: Bioenergetics, signaling and manipulation for therapy

We survey the historical development of scientific knowledge surrounding Vitamin B3, and describe the active metabolite forms of Vitamin B3, the pyridine dinucleotides NAD+ and NADP+ which are essential to cellular processes of energy metabolism, cell protection and biosynthesis. The study of NAD+ has become reinvigorated by new understandings that dynamics within NAD+ metabolism trigger major signaling processes coupled to effectors (sirtuins, PARPs, and CD38) that reprogram cellular metabolism using NAD+ as an effector substrate. Cellular adaptations include stimulation of mitochondrial biogenesis, a process fundamental to adjusting cellular and tissue physiology to reduced nutrient availability and/or increased energy demand. Several mammalian metabolic pathways converge to NAD+, including tryptophan-derived de novo pathways, nicotinamide salvage pathways, nicotinic acid salvage and nucleoside salvage pathways incorporating nicotinamide riboside and nicotinic acid riboside. Key discoveries highlight a therapeutic potential for targeting NAD+ biosynthetic pathways for treatment of human diseases. A recent emergence of understanding that NAD+ homeostasis is vulnerable to aging and disease processes has stimulated testing to determine if replenishment or augmentation of cellular or tissue NAD+ can have ameliorative effects on aging or disease phenotypes. This experimental approach has provided several proofs of concept successes demonstrating that replenishment or augmentation of NAD+ concentrations can provide ameliorative or curative benefits. Thus NAD+ metabolic pathways can provide key biomarkers and parameters for assessing and modulating organism health.

The Importance of Quality Specifications in Safety Assessments of Amino Acids: The Cases of l-Tryptophan and l-Citrulline

The increasing consumption of amino acids from a wide variety of sources, including dietary supplements, natural health products, medical foods, infant formulas, athletic and work-out products, herbal medicines, and other national and international categories of nutritional and functional food products, increases the exposure to amino acids to amounts far beyond those normally obtained from the diet, thereby necessitating appropriate and robust safety assessments of these ingredients. Safety assessments of amino acids, similar to all food constituents, largely rely on the establishment of an upper limit [Tolerable Upper Intake Level (UL)] considered to be a guide for avoiding high intake, above which adverse or toxic effects might occur. However, reliable ULs have been difficult or impossible to define for amino acids because of inadequate toxicity studies in animals and scarce or missing clinical data, as well as a paucity or absence of adverse event reporting data. This review examines 2 amino acids that have been associated with in-market adverse events to show how quality specifications might have helped prevent the adverse clinical outcomes. We further highlight the importance of various factors that should be incorporated into an overall safety assessment of these and other amino acids. In addition to the traditional reliance on the established UL, well-defined quality specifications, review of synthesis and production strategies, potential interactions with drugs, contraindications with certain disease states, and cautionary use within certain age groups should all be taken into consideration.