Gastrointestinal Handling of Water-Soluble Vitamins

6PPD impairs growth performance by inducing intestinal oxidative stress and ferroptosis in zebrafish

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), a tire-derived pollutant, has gained increasing attention due to its potential toxicity to aquatic organisms. Although previous studies have revealed that 6PPD impacts early developmental stages of larval fish, its effects on adult fish, particularly on key organs, remain unclear. In this study, we observed that adult zebrafish exposed to 6PPD exhibited reduced growth performance and increased fecal output. Histological examination with hematoxylin and eosin (H&E) staining revealed damage to the intestinal villi and a reduction in goblet cell numbers, indicating that 6PPD impairs growth performance by disrupting the digestive system. Comparative transcriptomic analysis revealed that 6PPD caused significant changes in the expression of 727 genes in the intestine, of which 280 genes were up-regulated and 447 genes were down-regulated. These genes were primarily associated with nutrient digestion and absorption, energy metabolism, immune response, and redox regulation. Mechanistically, 6PPD induced oxidative stress and triggered ferroptosis in the intestine, leading to structural damage of the intestinal villi. Treatment with the antioxidant N-acetylcysteine (NAC) alleviated 6PPD-induced oxidative stress and ferroptosis, thereby improving intestinal villi structure and promoting fish growth. This study provides insights into the mechanisms by which 6PPD impairs growth in adult zebrafish and highlights NAC as a potential therapeutic strategy to mitigate its toxicity.

Oxidative Stress in Maternal and Offspring Kidney Disease and Hypertension: A Life-Course Perspective

Kidney disease and hypertension are interconnected, prevalent conditions that affect both pregnant women and children. Oxidative stress occurs when reactive oxygen species or reactive nitrogen species exceed the capacity of antioxidant systems. It plays a critical role in kidney development, resulting in kidney programming and increased risks for kidney disease and hypertension across the life course. Animal models have significantly advanced our understanding of oxidative stress-related kidney programming, the molecular mechanisms involved, and early-life antioxidant interventions to prevent kidney disease. This review critically examines the influence of perinatal oxidative stress on kidney development, highlighting its long-term effects on kidney outcomes and susceptibility to hypertension. It also explores the potential of antioxidant-based interventions in preventing kidney disease and hypertension. Furthermore, the review addresses the existing gap between insights gained from animal models and their translation into clinical practices, emphasizing the challenges and opportunities for future research in this area.

High-dose thiamine supplementation ameliorates obesity induced by a high-fat and high-fructose diet in mice by reshaping gut microbiota

Introduction

Thiamine (vitamin B1) in the gut is crucial for maintaining intestinal homeostasis and host health. Our previous study identified significantly lower levels of fecal thiamine in individuals with obesity; however, its potential and mechanisms for alleviating obesity induced by a high-fat and high-fructose diet (HFFD) remain unclear. Therefore, in the present study, the effects of high-dose thiamine supplementation on HFFD-induced obesity and gut microbiota dysbiosis were investigated.

Methods

HFFD-fed mice were supplemented with high-dose thiamine for eight weeks. Biochemical analysis and histological analysis were conducted to assess phenotypic changes. Fecal 16S rRNA gene sequencing was performed to analyze alterations in the gut microbiota.

Results

The results showed that high-dose thiamine supplementation for eight weeks could significantly alleviate symptoms of HFFD-induced obesity and improve HFFD-induced intestinal epithelial barrier dysfunction by enhancing the tight junction function. Furthermore, oral administration of high-dose thiamine also regulated HFFD-induced gut microbiota dysbiosis by reshaping its structure and composition of gut microbiota, such as increasing the relative abundance of Actinobacteria and Bifidobacterium pseudolongum, and reducing the relative abundance of Proteobacteria and Ruminococcus gnavus, accompanied by decreased level of gut-derived endotoxin. Finally, significant correlations were found between obesity-related phenotypes and gut microbiota through correlation analysis.

Conclusion

Our findings suggest that the potential mechanism by which high-dose thiamine supplementation alleviated HFFD-induced obesity might involve reshaping gut microbiota and restoring the intestinal barrier, thereby ameliorating gut microbiota-related endotoxemia.

Therapeutic Potential of Bifidobacterium longum subsp. infantis B8762 on Gut and Respiratory Health in Infant

Respiratory tract and gastrointestinal infections in pediatric populations are major public health concerns. Addressing these challenges necessitates effective preventative and therapeutic strategies. This study assessed the efficacy of the probiotic Bifidobacterium longum subsp. infantis B8762 (0.5 × 1010 CFU) in reducing the duration and frequency of these infections in young children. In a randomized trial, 115 eligible children were assigned to either the probiotic (n = 57; 3.51 ± 0.48 months old) or placebo (n = 58; 2.78 ± 0.51 months old) group, with daily consumption for 4 weeks. The probiotic group demonstrated a lower duration of infections than the placebo group (p < 0.05). The probiotic group also showed fewer clinical visits due to respiratory and gastrointestinal problems as compared to the placebo group (p = 0.009 & p = 0.004, respectively). Oral swab samples revealed that the placebo group had higher levels of pro-inflammatory cytokine TNF-α after 4 weeks (p = 0.033), while the probiotic group demonstrated a balanced cytokine response, indicating modulation of the immune system. Genomic analysis showed that B8762 harbors various genes for the synthesis of proteins and vitamins crucial for the gut health of children. Both the clinical and genomic findings suggested that B8762 offered a therapeutic effect on gut and respiratory health in children, highlighting its potential in managing common pediatric infections.

Limitations and Challenges of Antioxidant Therapy

Our bodies are constantly exposed to or producing free radicals nearly on a daily basis. These highly reactive molecules are generated through a variety of internal and external processes and pathways within the body. If these free radicals are not neutralized by antioxidants, they can lead to a state of oxidative stress, which has been linked to a wide range of severe and debilitating disorders affecting various systems in the human body. This involves neurodegenerative diseases, diabetes, atherosclerosis, fatty liver, inflammation, and aging. Thankfully, the human body is armed with a repertoire of powerful antioxidants with different natures and modes of action. The recent decades witnessed the publication of enormous papers proving antioxidant activity of a novel synthesized compound, plant extract, or a purified drug in vitro, in vivo, and even on human beings. However, the efficacy of antioxidant therapies in clinical trials, including selenium, vitamin C, vitamin E, and vitamin A, has been notably inconsistent. This inconsistency can be primarily ascribed to different factors related to the nature of free radical generation, purpose and the specific type of therapy employed, and the intricate oxidative stress connected network, among others. Collectively, these factors will be explored in this review article to decipher the observed shortcomings in the application of antioxidant therapies within clinical settings.

IQGAP-2: a novel interacting partner with the human colonic thiamin pyrophosphate transporter

The human colonic thiamin pyrophosphate transporter (hcTPPT) mediates the uptake of the microbiota-generated and phosphorylated form of vitamin B1 (i.e., thiamin pyrophosphate) in the large intestine. Expression of hcTPPT along the absorptive tract is restricted to the large intestine, and the transporter is exclusively localized at the apical membrane domain of the polarized epithelial cells/colonocytes. Previous studies have characterized different physiological/pathophysiological aspects of the hcTPPT system, but nothing is currently known on whether the transporter has interacting partner(s) that affect its physiology/biology. We addressed this issue using a Y2H to screen a human colonic cDNA library and have identified three putative interactors, namely IQGAP-2, SNX-6, and DMXL-1. Focusing on IQGAP-2 (whose expression in human colonocytes is the highest), we found (using fluorescent microscopy imaging and coimmunoprecipitation approaches) the putative interactor to colocalize with hcTPPT and to directly interact with the transporter. Also, overexpressing IQGAP-2 in NCM460 cells and in human primary differentiated colonoid monolayers was found to lead to significant (P < 0.01) induction in TPP uptake, while knocking down (using gene-specific siRNAs) caused significant (P < 0.01 and P < 0.05) decrease in uptake. Furthermore, overexpressing IQGAP-2 in NCM460 cells was found to lead to a significant enhancement in hcTPPT protein stability. Finally, we found the expression of IQGAP-2 to be markedly suppressed in conditions/factors that negatively impact colonic TPP uptake. These results identify the IQGAP-2 as an interacting partner with the hcTPPT in human colonocytes and show that this interaction has physiological and biological consequences.NEW & NOTEWORTHY This study reports on the identification of IQGAP-2 as an interacting partner with the hcTPPT in human colonocytes and how that impacts the transporter's physiology and cell biology.

Bacterial lipopolysaccharide inhibits free thiamin uptake along the intestinal tract via interference with membrane expression of thiamin transporters 1 and 2

This study examined the effect of exposure of small and large intestinal epithelial cells to the bacterial lipopolysaccharide (LPS) on uptake of free form of vitamin B1, i.e., thiamin. The intestinal tract encounters two sources of thiamin: diet and the gut microbiota. Absorption of thiamin in both the small and large intestine occurs via a carrier-mediated process that involves thiamin transporters 1 and 2 (THTR-1 and -2). Complementary in vitro (human duodenal epithelial HuTu-80 cells and human colonic epithelial NCM460 cells), in vivo (mice), and ex vivo (human primary differentiated enteroid and colonoid monolayers) models were used. The results showed that exposure to LPS causes a significant inhibition in carrier-mediated [3H]-thiamin uptake by small and large intestinal epithelia, with no change in the levels of expression of THTR-1 and -2 mRNAs and their total cellular proteins. However, a significant decrease in the fractions of the THTR-1 and -2 proteins that are expressed at the cell membranes of these epithelial cells was observed. These effects of LPS appeared to involve a protein kinase A (PKA) signaling pathway as activating this pathway caused a reversal in the inhibition of thiamin uptake and level of expression of its transporters at the cell membrane. These findings demonstrate that exposure of gut epithelia to LPS (a situation that occurs under different pathological conditions) leads to inhibition in thiamin uptake due to a decrease in level of expression of its transporters at the cell membrane that is likely mediated via a PKA signaling pathway. NEW & NOTEWORTHY This study shows that the exposure of gut epithelial cells to bacterial LPS negatively impact the uptake process of the free form of vitamin B1 (i.e., thiamin). This appears to be mediated via suppression in the level of thiamin transporters 1 and 2 (THTR-1 and -2) expression at the cell membrane and involves a protein kinase A (PKA) signaling pathway.

Maternal Dietary Strategies for Improving Offspring Cardiovascular-Kidney-Metabolic Health: A Scoping Review

Dietary regulation has been recognized for its profound impact on human health. The convergence of cardiovascular, kidney, and metabolic disorders at the pathophysiological level has given rise to cardiovascular-kidney-metabolic (CKM) syndrome, which constitutes a significant global health burden. Maternal dietary nutrients play a crucial role in fetal development, influencing various programmed processes. This review emphasizes the effects of different types of dietary interventions on each component of CKM syndrome in both preclinical and clinical settings. We also provide an overview of potential maternal dietary strategies, including amino acid supplementation, lipid-associated diets, micronutrients, gut microbiota-targeted diets, and plant polyphenols, aimed at preventing CKM syndrome in offspring. Additionally, we discuss the mechanisms mediated by nutrient-sensing signals that contribute to CKM programming. Altogether, we underscore the interaction between maternal dietary interventions and the risk of CKM syndrome in offspring, emphasizing the need for continued research to facilitate their clinical translation.

Mass spectrometry of water-soluble vitamins to establish a risk model for predicting recurrent spontaneous abortion

The adverse pregnancy outcomes, including recurrent spontaneous abortion (RSA), are strongly correlated with water-soluble vitamins, but how to predict RSA occurrence using them remains unsatisfactory. This study aims to investigate the possibility of predicting RSA based on the baseline levels of water-soluble vitamins tested by ultra-liquid chromatography-tandem mass spectrometry. A total of 918 pregnant women was consecutively enrolled in this cross-sectional study. According to the miscarriage numbers, they were divided into normal first pregnancy (NFP, n = 608), once spontaneous abortion (OSA, n = 167), and continuous spontaneous abortion (CSA, n = 143) groups. The Cox proportional-hazards regression model was employed to establish a risk model for predicting RSA. The RSA occurrence was 6.54% in overall pregnant women, with a prevalence of 12.57% in the OSA group and 27.27% in the CSA group. Significant differences were observed in baseline deficiencies of vitamin B3, B5, B6, and B9 among NFP, OSA, and CSA groups (χ2 = 12.191 ~ 37.561, all P < 0.001). Among these vitamins, B9 (HR = 0.89 and 0.88, all P < 0.001) and B6 (HR = 0.83 and 0.78, all P < 0.05) were identified as independent factors in both the OSA and CSA groups; whereas B5 was identified as an additional independent factor only in the CSA group (HR = 0.93, P = 0.005). The Cox proportional-hazards model established using these three vitamins exhibited poor or satisfactory predictive performance in the OSA (Sen = 95.2%, Spe = 39.0%) and CSA (Sen = 92.3%, Spe = 60.6%) groups, respectively. However, B5, B6, and B9 compensatory levels were not associated with RSA occurrence (all P > 0.05). Our study presents a highly sensitive model based on mass spectrometry assay of baseline levels in B vitamins to predict the RSA occurrence as possible.

Effect of knocking out mouse Slc44a4 on colonic uptake of the microbiota-generated thiamine pyrophosphate and colon physiology

Humans and mammals obtain vitamin B1 from dietary and gut microbiota sources. A considerable amount of the microbiota-generated vitamin exists in the form of thiamine pyrophosphate (TPP), and colonocytes are capable of absorbing TPP via a specific carrier-mediated process that involves the colonic TPP transporter (cTPPT encoded by SLC44A4). Little is known about the relative contribution of the SLC44A4 transporter toward total colonic carrier-mediated TPP uptake and its role in colon physiology. To address these issues, we generated an Slc44a4 knockout (KO) mouse model (by Cre-Lox recombination) and found a near-complete inhibition in colonic carrier-mediated [3H]TPP uptake in the Slc44a4 KO compared with wild-type (WT) littermates. We also observed a significant reduction in KO mice's body weight and a shortening of their colon compared with WT. Using RNAseq and Ingenuity pathway analysis (IPA) approaches, we found that knocking out the colonic Slc44a4 led to changes in the level of expression of many genes, including upregulation in those associated with intestinal inflammation and colitis. Finally, we found that the Slc44a4 KO mice were more susceptible to the effect of the colitogenic dextran sodium sulfate (DSS) compared with WT animals, a finding that lends support to the recent prediction by multiple genome-wide association studies (GWAS) that SLC44A4 is a possible colitis susceptibility gene. In summary, the results of these investigations show that Slc44a4 is the predominant or only transporter involved in the colonic uptake of TPP, that the transporter is important for colon physiology, and that its deletion increases susceptibility to inflammation.NEW & NOTEWORTHY This study shows that Slc44a4 is the predominant or only transport system involved in the uptake of the gut microbiota-generated thiamine pyrophosphate (TPP) in the colon and that its deletion affects colon physiology and increases its susceptibility to inflammation.

The Impact of Vitamin Deficiencies on Oral Manifestations in Children

Vitamins play a vital role in human health, particularly in the development and maintenance of oral health in children. These nutrients are broadly categorized into fat-soluble and water-soluble types, crucial for children's well-being. The objective of this study is to investigate the impact of vitamin deficiencies on the oral health of children, focusing on how these deficiencies contribute to various oral health issues and determining the relationship between specific vitamin shortages and oral diseases. Findings indicate that shortages in vitamins A and D lead to enamel issues and a higher susceptibility to dental diseases, vitamin E assists in treating oral mucositis, and vitamin K is essential for blood clotting in dental surgeries. Deficits in B-complex and vitamin C result in enamel hypomineralization and soft tissue ailments, including aphthous stomatitis and gingival petechiae. Additionally, a lack of vitamin B7 compromises the immune response, increasing oral candidiasis risk. Therefore, vitamin deficiencies markedly affect children's oral health, highlighting the need for joint efforts between dental professionals and caregivers for effective pediatric care. Addressing vitamin deficiencies through supplementation and tailored dental care emphasizes the significance of nutritional health in children's overall and dental well-being, advocating for a collaborative approach to achieve optimal health outcomes.

Simultaneous quantification of seven B vitamins in human faeces by stable isotope label-based high-performance liquid chromatography-tandem mass spectrometry

B vitamins in the human distal gut are primarily derived from the gut microbiota because daily dietary vitamins are fully absorbed in the small intestine under normal dietary and physiological conditions. Quantitative determination of B vitamins in the distal gut and faecal samples is crucial for understanding the intricate relationship between gut B vitamins, gut microbiota, and host health. In this study, we developed a rapid, robust, and reliable method with a simple extraction procedure for the simultaneous analysis of seven B vitamins in human faeces using high-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (HPLC-ESI-MS/MS) with stable isotope-labelled internal standards. A protein precipitation approach using methanol as the precipitant was employed to extract vitamin B from human faecal samples. Seven B vitamins were adequately separated and quantified within 9 min by HPLC-ESI-MS/MS with a Pursuit PFP column (2.0 ×150 mm, 3.0 µm), including vitamins B1, B2, B3, B5, pyridoxic acid, pyridoxine, and B7. The lower limits of quantification were within the range of 0.1-25 ng mL-1. The intra-day and inter-day precision and accuracy were both within 15 %. The validated method was successfully applied to 55 faecal samples collected from healthy individuals, patients with type 2 diabetes, and obese patients. Compared with healthy controls, obese patients had lower faecal concentrations of vitamins B1 and B3 and pyridoxic acid, whereas patients with type 2 diabetes had lower faecal concentrations of vitamins B1 and B5.

Bacterial lipopolysaccharide inhibits colonic carrier-mediated uptake of thiamin pyrophosphate: roles for TLR4 receptor and NF-κB/P38/JNK signaling pathway

This study investigated the effect of the bacterial endotoxin lipopolysaccharide (LPS) on colonic uptake of thiamin pyrophosphate (TPP), the biologically active form of vitamin B1 that is generated by gut microbiota. We used three complementary models in our study: in vitro (human-derived colonic epithelial NCM460), ex vivo (human differentiated colonoid monolayers), and in vivo (mouse colonic tissue). The results showed that exposure of NCM460 cells to LPS leads to a significant inhibition of carrier-mediated TPP uptake as well as in decreased expression of the colonic TPP transporter (cTPPT) protein, mRNA, and heterologous nuclear RNA (hnRNA) compared with untreated controls. Similarly, exposure of human differentiated colonoid monolayers and mice to LPS caused significant inhibition in colonic carrier-mediated TPP uptake and in cTPPT protein, mRNA, and hnRNA expression. The effect of LPS on colonic TPP uptake and cTTPT expression was also found to be associated with a significant reduction in activity of the SLC44A4 promoter as well as in decreased expression of the nuclear factor Elf-3 (E74-like ETS transcription factor 3), which is needed for promoter activity. Finally, we found that knocking down the Toll-like receptor 4 (TLR4) and blocking the nuclear factor kappa B (NF-κB), JNK, and p38 signaling pathways with the use of pharmacological inhibitors lead to significant abrogation in the degree of LPS-mediated inhibition in TPP uptake and cTPPT expression. These results demonstrated that exposure of colonic epithelia to LPS inhibits colonic TPP uptake via transcriptional mechanism(s) and that the effect is mediated via TLR4 receptor and NF-κB/p38/JNK signaling pathways.NEW & NOTEWORTHY This study examined the effect of the bacterial lipopolysaccharide (LPS) on the colonic uptake of thiamin pyrophosphate (TPP), the biologically active form of vitamin B1. Three complementary models were used: in vitro (human NCM460 cells), ex vivo (human colonoids), and in vivo (mice). The results showed LPS to significantly suppress TPP uptake and the expression of its transporter, and that these effects are mediated via the membrane TLR4 receptor, and involve the NF-κB/p38/JNK signaling pathways.

Perinatal Oxidative Stress and Kidney Health: Bridging the Gap between Animal Models and Clinical Reality

Oxidative stress arises when the generation of reactive oxygen species or reactive nitrogen species overwhelms antioxidant systems. Developing kidneys are vulnerable to oxidative stress, resulting in adult kidney disease. Oxidative stress in fetuses and neonates can be evaluated by assessing various biomarkers. Using animal models, our knowledge of oxidative-stress-related renal programming, the molecular mechanisms underlying renal programming, and preventive interventions to avert kidney disease has grown enormously. This comprehensive review provides an overview of the impact of perinatal oxidative stress on renal programming, the implications of antioxidant strategies on the prevention of kidney disease, and the gap between animal models and clinical reality.

Intermediate role of gut microbiota in vitamin B nutrition and its influences on human health

Vitamin B consists of a group of water-soluble micronutrients that are mainly derived from the daily diet. They serve as cofactors, mediating multiple metabolic pathways in humans. As an integrated part of human health, gut microbiota could produce, consume, and even compete for vitamin B with the host. The interplay between gut microbiota and the host might be a crucial factor affecting the absorbing processes of vitamin B. On the other hand, vitamin B supplementation or deficiency might impact the growth of specific bacteria, resulting in changes in the composition and function of gut microbiota. Together, the interplay between vitamin B and gut microbiota might systemically contribute to human health. In this review, we summarized the interactions between vitamin B and gut microbiota and tried to reveal the underlying mechanism so that we can have a better understanding of its role in human health.

Tumor necrosis factor α impedes colonic thiamin pyrophosphate and free thiamin uptake: involvement of JNK/ERK1/2-mediated pathways

The aim of this study was to examine the effect of TNFα (i.e., a predominant proinflammatory cytokine produced during chronic gut inflammation) on colonic uptake of thiamin pyrophosphate (TPP) and free thiamin, forms of vitamin B1 that are produced by the gut microbiota and are absorbed via distinct carrier-mediated systems. We utilized human-derived colonic epithelial CCD841 and NCM460 cells, human differentiated colonoid monolayers, and mouse intact colonic tissue preparations together with an array of cellular/molecular approaches in our investigation. The results showed that exposure of colonic epithelial cells to TNFα leads to a significant inhibition in TPP and free thiamin uptake. This inhibition was associated with: 1) a significant suppression in the level of expression of the colonic TPP transporter (cTPPT; encoded by SLC44A4), as well as thiamin transporters-1 & 2 (THTR-1 & -2; encoded by SLC19A2 & SLC19A3, respectively); 2) marked inhibition in activity of the SLC44A4, SLC19A2, and SLC19A3 promoters; and 3) significant suppression in level of expression of nuclear factors that are needed for activity of these promoters (i.e., CREB-1, Elf-3, NF-1A, SP-1). Furthermore, the inhibitory effects were found to be mediated via JNK and ERK1/2 signaling pathways. We also examined the level of expression of cTPPT and THTR-1 & -2 in colonic tissues of patients with active ulcerative colitis and found the levels to be significantly lower than in healthy controls. These findings demonstrate that exposure of colonocytes to TNFα suppresses TPP and free thiamin uptake at the transcriptional level via JNK- and Erk1/2-mediated pathways.

AGA-PancreasFest Joint Symposium on Exocrine Pancreatic Insufficiency

Exocrine pancreatic insufficiency (EPI) is a clinically defined syndrome based on the physician's assessment of a patient's maldigestion. However, current clinical definitions are inadequate in determining (1) the threshold of reduced pancreatic digestive enzyme secretion that determines "pancreatic insufficiency" in an individual patient; (2) the role of pancreatic function tests; (3) effects of differing metabolic needs, nutrition intake, and intestinal function/adaptation (4) when pancreatic enzyme replacement therapy is needed; and (5) how to monitor and titrate multiple therapies. Experts and key opinion leaders were invited to PancreasFest 2021 to discuss and help clarify mechanistic issues critical to defining EPI and to address misconceptions and barriers limiting advancements in patient care. Clinically EPI is defined as inadequate delivery of pancreatic digestive enzymes to meals to meet nutritional needs and is reversed with appropriate treatment. A new mechanistic definition of EPI was proposed that includes the disorders essence and character: (1) EPI is a disorder caused by failure of the pancreas to deliver a minimum/threshold level of specific pancreatic digestive enzymes to the intestine in concert with ingested nutrients, followed by enzymatic digestion of a series of individual snacks and meals over time to meet nutritional and metabolic needs, given (a) the specific macronutritional and micronutritional needs; (b) nutrient intake; (c) exocrine pancreatic function; and (d) intestinal anatomy, function, diseases, and adaptative capacity. (2) EPI is characterized by variable deficiencies in micronutrients and macronutrients, especially essential fats and fat-soluble vitamins, by gastrointestinal symptoms of nutrient maldigestion and by improvement or correction of nutritional state with lifestyle changes, disease treatment, optimized diet, dietary supplements, and/or administration of adequate pancreatic enzyme replacement therapy. EPI is complex and individualized and multidisciplinary approaches are needed to optimize therapy. Better pancreas function tests and biomarkers are needed to diagnose EPI and guide treatment.

Metabolic Syndrome Programming and Reprogramming: Mechanistic Aspects of Oxidative Stress

Metabolic syndrome (MetS) is a worldwide public health issue characterized by a set of risk factors for cardiovascular disease. MetS can originate in early life by developmental programming. Increasing evidence suggests that oxidative stress, which is characterized as an imbalance between reactive oxygen species (ROS), nitric oxide (NO), and antioxidant systems, plays a decisive role in MetS programming. Results from human and animal studies indicate that maternal-derived insults induce MetS later in life, accompanied by oxidative stress programming of various organ systems. On the contrary, perinatal use of antioxidants can offset oxidative stress and thereby prevent MetS traits in adult offspring. This review provides an overview of current knowledge about the core mechanisms behind MetS programming, with particular focus on the occurrence of oxidative-stress-related pathogenesis as well as the use of potential oxidative-stress-targeted interventions as a reprogramming strategy to avert MetS of developmental origins. Future clinical studies should provide important proof of concept for the effectiveness of these reprogramming interventions to prevent a MetS epidemic.

Unveiling of dietary and gut-microbiota derived B vitamins: Metabolism patterns and their synergistic functions in gut-brain homeostasis

Nutrition-gut cross-talk holds a vital position in sustaining intestinal function, and micronutrient metabolism has emerged as the foremost metabolic pathway to preserve gut homeostasis. Among micronutrients, B vitamins have evolved prior to DNA/RNA and are known for their vital roles for major evolutionary transitions in extant organisms. Despite their universal requirement and critical role, not all the three domains of life are endowed with a natural ability for de novo B vitamins synthesis. The human gut microbiome constitutes prototrophs and auxotroph which are entirely dependent on dietary intake and gut microbial production of B vitamins. The syntrophic metabolism involving cross-feeding of B vitamins and community-wide exchange between commensal bacteria elicit important changes in the diversity and composition of the human gut microbiome. Hereto, we discuss the B-vitamins sharing among prototrophic and auxotrophic gut bacteria, their absorption in small intestine and transport in distal gut, functional role in relation to the gut homeostasis and symptoms linked to their deficiency. We also briefly explore their potential involvement as psychobiotics in brain energetic metabolism (kynurenines/tryptophan pathway) for neurological functions and highlight their deficiency related malfunctioning.

Antioxidant Therapy in Cancer: Rationale and Progress

Cancer is characterized by increased oxidative stress, an imbalance between reactive oxygen species (ROS) and antioxidants. Enhanced ROS accumulation, as a result of metabolic disturbances and signaling aberrations, can promote carcinogenesis and malignant progression by inducing gene mutations and activating pro-oncogenic signaling, providing a possible rationale for targeting oxidative stress in cancer treatment. While numerous antioxidants have demonstrated therapeutic potential, their clinical efficacy in cancer remains unproven. Here, we review the rationale for, and recent advances in, pre-clinical and clinical research on antioxidant therapy in cancer, including targeting ROS with nonenzymatic antioxidants, such as NRF2 activators, vitamins, N-acetylcysteine and GSH esters, or targeting ROS with enzymatic antioxidants, such as NOX inhibitors and SOD mimics. In addition, we will offer insights into prospective therapeutic options for improving the effectiveness of antioxidant therapy, which may expand its applications in clinical cancer treatment.

Effect of different dosage of sodium butyrate and niacin on growth, fecal microbiota and vitamin B metabolism in weaned piglets

AIMS

Our study aimed to evaluate the effects of different dosages of sodium butyrate and niacin on the growth performance, fecal vitamin B and microbiota in weaned piglets.

METHODS AND RESULTS

Seventy-two weaned piglets (Duroc×Landrace×Yorkshire, age of 21d) were randomly assigned to 1 of 6 treatments (12 pigs / treatment): the control (CT) group was administered a basal diet. The groups which concentration ratio of sodium butyrate to niacin were 100: 1, 100: 2, 100: 4, 100: 8 and 100: 16 (BN1, BN2, BN4, BN8, BN16) were administered a basal diet supplemented with 2000 mg·kg^-1 sodium butyrate and 20 mg·kg^-1 , 40 mg·kg^-1 , 80 mg·kg^-1 , 160 mg·kg^-1 or 320 mg·kg^-1 niacin. After 14-d treatment, the samples were collected. The results showed that feed conversion rate (FCR) was reduced and average daily gain (ADG) was increased in BN2 (P < 0.05). The diarrhea index of pigs decreased with the low supplement. Additionally, compared with CT group, other groups significantly increased (P < 0.05) the abundance of Firmicutes (BN4, phylum), Lactobacillaceae (BN8, family), Megasphaera (BN8, genus), and Lactobacillus (BN8, genus). Furthermore, the sodium butyrate and niacin supplementation influence vitamin B1, vitamin B2, pyridoxine, niacin, nicotinamide, and vitamin B12 (P < 0.05). Correlation analysis of the association of microorganisms with vitamin B indicated that changes of vitamin B metabolism have potential correlation with alterations of fecal microbiota in weaned piglets.

CONCLUSIONS

The results indicated that adding of sodium butyrate and niacin in the diet could promote the performance and improve the fecal microbiota and vitamin B metabolism in weaned piglets.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our study might provide clues to the research of correlations between fecal bacteria and fecal vitamin B, and these findings will contribute to the direction of future research in weaned piglets.

Hypoxia inhibits colonic uptake of the microbiota-generated forms of vitamin B1 via HIF-1α-mediated transcriptional regulation of their transporters

Hypoxia exerts profound effects on cell physiology, but its effect on colonic uptake of the microbiota-generated forms of vitamin B1 (i.e., thiamin pyrophosphate [TPP] and free thiamine) has not been described. Here, we used human colonic epithelial NCM460 cells and human differentiated colonoid monolayers as in vitro and ex vivo models, respectively, and were subjected to either chamber (1% O2, 5% CO2, and 94% N2) or chemically (desferrioxamine; 250 μM)-induced hypoxia followed by determination of different physiological-molecular parameters. We showed that hypoxia causes significant inhibition in TPP and free thiamin uptake by colonic NCM460 cells and colonoid monolayers; it also caused a significant reduction in the expression of TPP (SLC44A4) and free thiamin (SLC19A2 and SLC19A3) transporters and in activity of their gene promoters. Furthermore, hypoxia caused a significant induction in levels of hypoxia-inducible transcription factor (HIF)-1α but not HIF-2α. Knocking down HIF-1α using gene-specific siRNAs in NCM460 cells maintained under hypoxic conditions, on the other hand, led to a significant reversal in the inhibitory effect of hypoxia on TPP and free thiamin uptake as well as on the expression of their transporters. Finally, a marked reduction in level of expression of the nuclear factors cAMP responsive element-binding protein 1 and gut-enriched Krüppel-like factor 4 (required for activity of SLC44A4 and SLC19A2 promoters, respectively) was observed under hypoxic conditions. In summary, hypoxia causes severe inhibition in colonic TPP and free thiamin uptake that is mediated at least in part via HIF-1α-mediated transcriptional mechanisms affecting their respective transporters.

Regulation of NAD+ metabolism in aging and disease

More than a century after discovering NAD⁺, information is still evolving on the role of this molecule in health and diseases. The biological functions of NAD⁺ and NAD⁺ precursors encompass pathways in cellular energetics, inflammation, metabolism, and cell survival. Several metabolic and neurological diseases exhibit reduced tissue NAD⁺ levels. Significantly reduced levels of NAD⁺ are also associated with aging, and enhancing NAD⁺ levels improved healthspan and lifespan in animal models. Recent studies suggest a causal link between senescence, age-associated reduction in tissue NAD⁺ and enzymatic degradation of NAD⁺. Furthermore, the discovery of transporters and receptors involved in NAD⁺ precursor (nicotinic acid, or niacin, nicotinamide, and nicotinamide riboside) metabolism allowed for a better understanding of their role in cellular homeostasis including signaling functions that are independent of their functions in redox reactions. We also review studies that demonstrate that the functional effect of niacin is partially due to the activation of its cell surface receptor, GPR109a. Based on the recent progress in understanding the mechanism and function of NAD⁺ and NAD⁺ precursors in cell metabolism, new strategies are evolving to exploit these molecules' pharmacological potential in the maintenance of metabolic balance.

Developmental maturation of the colonic uptake process of the microbiota-generated thiamin pyrophosphate

The water-soluble vitamin B1 is essential for normal human health and physiology. In its main biologically active form, i.e., thiamin pyrophosphate (TPP), the vitamin plays many critical roles in cell metabolism; thus, its deficiency leads to a variety of adverse effects. Humans/mammals obtain vitamin B1 from two exogenous sources: diet and gut microbiota. Considerable amount of the microbiota-generated vitamin B1 exists in the form of TPP, and colonocytes can efficiently absorb this TPP via a high-affinity and specific carrier-mediated mechanism that involves the recently cloned colonic TPP transporter (cTPPT; product of SLC44A4 gene). There is nothing currently known about colonic uptake of TPP during early stages of life and whether the process undergoes developmental regulation. We addressed this issue using the mouse as animal model. Our results showed that colonic uptake of TPP undergoes developmental upregulation as the animal moves from the suckling period to weanling and adulthood. This upregulation in uptake was found to be associated with a parallel induction in level of expression of the cTPPT protein, mRNA, and heterogeneous nuclear RNA, suggesting possible involvement of transcriptional mechanism(s). We also found a parallel upregulation in the level of expression of the two nuclear factors that drive activity of the SLC44A4 promoter (i.e., CREB-1 and Elf-3) with maturation. These results demonstrate, for the first time, to our knowledge, that colonic TPP uptake process and cTPPT expression are developmentally upregulated and that this upregulation is likely driven via transcriptional mechanism(s).NEW & NOTEWORTHY The colonic carrier-mediated uptake process of the microbiota-generated and phosphorylated form of vitamin B1, i.e., thiamin pyrophosphate, undergoes ontogenic changes that parallel the development of the gut microbiota (and their ability to generate vitamins) during early stages of life.

Isolated Pulvinar/Hockey Stick Sign in Nonalcoholic Wernicke's Encephalopathy

BACKGROUND Wernicke's encephalopathy (WE), a commonly misdiagnosed and underdiagnosed pathology, presents with altered mental status, ataxia, and ophthalmoplegia. WE is most commonly caused by excessive alcohol use, but also has diverse nonalcoholic etiologies. Here we describe 2 cases of nonalcoholic WE with different etiologies that were initially misdiagnosed due to lack of correlation of magnetic resonance imaging (MRI) findings with clinical information. CASE REPORT Patient A, a 50-year-old woman with recent gastric sleeve surgery, presented with horizontal gaze-evoked nystagmus, ataxia, and altered mental status. MRI fluid-attenuated inversion recovery (FLAIR) revealed isolated bilateral, symmetrical, thalamic hyperintensities, initially diagnosed as variant Creutzfeldt-Jakob disease. A review of imaging and clinical presentation provided an alternate diagnosis of nonalcoholic WE secondary to nutritional deficiency. Intravenous (IV) thiamine improved symptoms with resolution of MRI findings 6 months later. Patient B, a 64-year-old woman, presented with nausea, vomiting, dizziness, altered mental status, and weight loss. MRI FLAIR revealed isolated bilateral, symmetrical, thalamic hyperintensities, initially determined to be ischemia, prompting stroke management. A diagnosis of nonalcoholic WE was suggested, given the patient's low thiamine levels and history of malnutrition, and was confirmed by her excellent therapeutic response to IV thiamine. CONCLUSIONS Nonalcoholic WE remains a challenging diagnosis because of the variable clinical presentation, myriad of underlying etiologies, and lack of standardized diagnostic laboratory tests. A multidisciplinary approach with close collaboration between the radiologist and clinical care team is critical to narrow down the differential and initiate correct management. WE is a reversible disease with catastrophic consequences if it is not recognized and treated promptly.

Wernicke's encephalopathy - from basic science to clinical practice. Part 1: Understanding the role of thiamine

Wernicke's encephalopathy (WE) is an acute neuropsychiatric state. Untreated, WE can lead to coma or death, or progress to Korsakoff syndrome (KS) - a dementia characterized by irreversible loss of anterograde memory. Thiamine (vitamin B1) deficiency lies at the heart of this condition. Yet, our understanding of thiamine regarding prophylaxis and treatment of WE remains limited. This may contribute to the current undertreatment of WE in clinical practice. The overall aim of this review is to identify the best strategies for prophylaxis and treatment of WE in regard to (a) dose of thiamine, (b) mode of administration, (c) timing of switch from one mode of administration to another, (d) duration of administration, and (e) use of magnesium along thiamine as an essential cofactor. Evidence from randomized controlled trials and other intervention studies is virtually absent. Therefore, we have to resort to basic science for proof of principle instead. Here, we present the first part of our clinical review, in which we explore the physiology of thiamine and the pathophysiology of thiamine deficiency. We first explore both of these in their historical context. We then review the pharmacodynamics and pharmacokinetics of thiamine, exploring the roles of the six currently known thiamine compounds, their transporters, and target enzymes. We also explore the significance of magnesium as a cofactor in thiamine-facilitated enzymatic reactions and thiamine transport. In the second (forthcoming) part of this review, we will use the findings of the current review to make evidence-based inferences about strategies for prophylaxis and treatment of WE.

Gut Microbiota Metabolism and Interaction with Food Components

The human gut contains trillions of microbes that play a central role in host biology, including the provision of key nutrients from the diet. Food is a major source of precursors for metabolite production; in fact, diet modulates the gut microbiota (GM) as the nutrients, derived from dietary intake, reach the GM, affecting both the ecosystem and microbial metabolic profile. GM metabolic ability has an impact on human nutritional status from childhood. However, there is a wide variability of dietary patterns that exist among individuals. The study of interactions with the host via GM metabolic pathways is an interesting field of research in medicine, as microbiota members produce myriads of molecules with many bioactive properties. Indeed, much evidence has demonstrated the importance of metabolites produced by the bacterial metabolism from foods at the gut level that dynamically participate in various biochemical mechanisms of a cell as a reaction to environmental stimuli. Hence, the GM modulate homeostasis at the gut level, and the alteration in their composition can concur in disease onset or progression, including immunological, inflammatory, and metabolic disorders, as well as cancer. Understanding the gut microbe–nutrient interactions will increase our knowledge of how diet affects host health and disease, thus enabling personalized therapeutics and nutrition.

Metagenomic analysis of microbe-mediated vitamin metabolism in the human gut microbiome

BACKGROUND

Human gut microbial communities have been known to produce vitamins, which are subsequently absorbed by the host in the large intestine. However, the relationship between species with vitamin pathway associated functional features or their gene abundance in different states of health and disease is lacking. Here, we analyzed shotgun fecal metagenomes of individuals from four different countries for genes that are involved in vitamin biosynthetic pathways and transport mechanisms and corresponding species' abundance.

RESULTS

We found that the prevalence of these genes were found to be distributed across the dominant phyla of gut species. The number of positive correlations were high between species harboring genes related to vitamin biosynthetic pathways and transporter mechanisms than that with either alone. Although, the range of total gene abundances remained constant across healthy populations at the global level, species composition and their presence for metabolic pathway related genes determine the abundance and functional genetic content of vitamin metabolism. Based on metatranscriptomics data, the equation between abundance of vitamin-biosynthetic enzymes and vitamin-dependent enzymes suggests that the production and utilization potential of these enzymes seems way more complex usage allocations than just mere direct linear associations.

CONCLUSIONS

Our findings provide a rationale to examine and disentangle the interrelationship between B-vitamin dosage (dietary or microbe-mediated) on gut microbial members and the host, in the gut microbiota of individuals with under- or overnutrition.