Epigenetic studies in children at risk of stunting and their parents in India, Indonesia and Senegal: a UKRI GCRF Action Against Stunting Hub protocol paper.

INTRODUCTION: In 2020, an estimated 150 million children under the age of 5 years were stunted. Stunting results from early-life adversity and it is associated with significant physical and cognitive deficit, lifelong socioeconomic disadvantage and reduced life expectancy. There is a need to understand the causes of stunting and its effects in order to develop strategies to avoid it and to mitigate the consequences once stunting has occurred. Epigenetics is an important mechanism through which early-life factors are thought to influence biological function, with long-term consequences. We describe a series of epigenetic studies designed to understand how early-life adversity results in stunting and to inform the development of practical tools such as predictive markers and therapeutic targets. This work is part of the UKRI GCRF Action Against Stunting Hub. METHODS AND ANALYSIS: The project-in India, Indonesia and Senegal-comprises an observational study of mothers, fathers, and offspring (n=500) spanning the first 1000 days of life, and an intervention study in each country. Epigenetic status (DNA methylation) is determined in saliva from babies collected within 1 month of birth and again at 18 months of age, and from mothers and fathers around the time of birth. Epigenome-wide analysis is carried out using the Illumina EPIC array, augmented by high-definition sequencing approaches. Statistical analysis is carried out at the level of candidate genes/regions, higher dimensional epigenetic states and epigenome-wide association. Data analysis focuses on the determinants of stunting, the effectiveness of interventions, population comparisons and the link between epigenetics and other thematic areas, which include anthropometry, microbiome, gut health, parasitology, cognition, nutrition, food hygiene and water sanitation, food systems and the home environment. ETHICS AND DISSEMINATION: This study has been approved by the relevant Ethics Committees in Indonesia, India and Senegal, and the UK. Research data will be published and posted in public repositories.

Eggs for Improving Nutrition, cognitive development and reducing linear growth retardation among Infants and young Children (ENRICH): protocol of an egg supplementation trial among children aged 9-18 months in Hyderabad, India.

INTRODUCTION: Evidence on the impact of nutrient-rich animal source foods such as eggs for improving child growth and cognition is inconsistent. This study aims to examine the impact of an egg intervention in children, along with behaviour change communication (BCC) to the mother, on linear growth and cognition, and nutritional status in children aged 9-18 months. METHODS AND ANALYSIS: A 9-month open-labelled randomised controlled trial will be conducted in three urban slums in Hyderabad, India, as a substudy of an observational cohort study (n=350) following pregnant women and their children until 18 months of age in a population at risk of stunting. The children born to women enrolled during the third trimester of pregnancy will be block randomised in a 1:4 ratio into the intervention (n=70) and control (n=280) groups. Children in the intervention group will be supplemented with one egg per day starting from 9 months until 18 months of age. BCC designed to enhance adherence to the intervention will be used. The control group will be a part of the observational cohort and will not receive any intervention from the study team. The primary outcome will be length-for-age z-scores, and the secondary outcomes will include cognition, blood biomarkers of nutritional status including fatty acid profile and epigenetic signatures linked with linear growth and cognition. Multivariate intention-to-treat analyses will be conducted to assess the effect of the intervention. ETHICS AND DISSEMINATION: The study is approved by the Institutional ethics committees of ICMR-National Institute of Nutrition, Hyderabad, India and London School of Hygiene and Tropical Medicine, UK. The results will be published in peer-reviewed journals and disseminated to policy-makers. Findings will also be shared with study participants and community leaders. TRIAL REGISTRATION NUMBER: CTRI/2021/11/038208.

Assessment of the role of gut health in childhood stunting in a multisite, longitudinal study in India, Indonesia and Senegal: a UKRI GCRF Action Against Stunting Hub protocol.

INTRODUCTION: Childhood stunting has a complex aetiology, with poor gut health being an important contributor. This study will assess inter-relationships between maternal and infant gut health indices and infant linear growth. Inter-relationships between gut health indices, systemic inflammation and growth hormones in early childhood will also be assessed. METHODS AND ANALYSIS: A longitudinal observational study of cohorts of 600 newborns and their mothers in India, Indonesia and Senegal will be conducted. Women will be recruited during pregnancy and their children followed up to age 24 months. Stool, urine and blood samples will be collected from the women and children for assessments of helminthic and protozoal parasites, bacterial pathogens, faecal microbiota taxa, biomarkers of environmental enteric dysfunction, systemic inflammation and growth hormones. Child anthropometric measurements will be collected at birth and at ages 3, 6, 9, 12, 18 and 24 months. The gut health indices will be integrated with cohort data from other Action Against Stunting Hub (AASH) workstreams for interdisciplinary analyses of childhood stunting and the development of a new typology of stunting. DISCUSSION: This study will advance scientific understanding of the role of gut health in childhood stunting and will contribute to a broader knowledge of the complex aetiology of this condition as part of the interdisciplinary AASH research to reduce the global burden of childhood stunting. ETHICS AND DISSEMINATION: This study has been approved by the relevant Ethics Committees in Senegal, India, and Indonesia and LSHTM. The results will be submitted for publication in peer-reviewed journals.

Fibroblast growth factor 21 as a potential master regulator in metabolic disorders.

FGF21 is an endocrine hormone that controls key metabolic processes and induces the synthesis of glucose transporters, resulting in increased glucose absorption levels in fat cells. It is expressed in multiple metabolically active organs and tissues. FGF21 is also a powerful regulator of glucose homeostasis as a direct downregulating gene of peroxisome proliferator-activated receptor (PPAR), which plays a role in regulating the activity of glucose and lipids. Attempts were made to understand various aspects related to FGF21, including properties like receptor binding and genomic linkage map, along with the information about the genes that function in the upregulation of FGF21 and how it, directly and indirectly, downregulates the genes that are vital in various metabolic pathways. Furthermore, various gene regulatory analyses on the specific gene concerning unique micro RNAs and long non-coding RNAs that target FGF21 and alter its functioning along with single-nucleotide polymorphisms (SNPs) were observed, that are the common cause of cell dysregulation, leading to different metabolic diseases and pathogenesis of cancer. Unique protein-protein interaction and cross talk between FGF21 and PPARγ shed light on their combined role in metabolic disorder-related regulatory activities. Its potential and unique role as an effective biomarker for various cardiovascular and metabolic disorders have also been highlighted. This study attempts to highlight the pleiotropic role of FGF21 activity following its overexpression and inhibition of cascades that results in the induction of obesity from diet and simultaneously signals adipocytes to absorb glucose and decrease triglyceride and blood sugar levels in diabetic models (after administration), rendering it a promising treatment for several metabolic and cardiovascular disorders.

Calorie Restriction-Regulated Molecular Pathways and Its Impact on Various Age Groups: An Overview.

Calorie restriction (CR) if planned properly with regular exercise at different ages can result in healthy weight loss. CR can also have different beneficial effects on improving lifespan and decreasing the age-associated diseases by regulating physiological, biochemical, and molecular markers. The different pathways regulated by CR include:(1) AMP-activated protein kinase (AMPK), which involves PGC-1α, SIRT1, and SIRT3. AMPK also effects myocyte enhancer factor 2 (MEF2), peroxisome proliferator-activated receptor delta, and peroxisome proliferator-activated receptor alpha, which are involved in mitochondrial biogenesis and lipid oxidation; (2) Forkhead box transcription factor's signaling is related to the DNA repair, lipid metabolism, protection of protein structure, autophagy, and resistance to oxidative stress; (3) Mammalian target of rapamycin (mTOR) signaling, which involves key factors, such as S6 protein kinase-1 (S6K1), mTOR complex-1 (mTORC1), and 4E-binding protein (4E-BP). Under CR conditions, AMPK activation and mTOR inhibition helps in the activation of Ulk1 complex along with the acetyltransferase Mec-17, which is necessary for autophagy; (4) Insulin-like growth factor-1 (IGF-1) pathway downregulation protects against cancer and slows the aging process; (5) Nuclear factor kappa B pathway downregulation decreases the inflammation; and (6) c-Jun N-terminal kinase and p38 kinase regulation as a response to the stress. The acute and chronic CR both shows antidepression and anxiolytic action by effecting ghrelin/GHS-R1a signaling. CR also regulates GSK3ß kinase and protects against age-related brain atrophy. CR at young age may show many deleterious effects by effecting different mechanisms. Parental CR before or during conception will also affect the health and development of the offspring by causing many epigenetic modifications that show transgenerational transmission. Maternal CR is associated with intrauterine growth retardation effecting the offspring in their adulthood by developing different metabolic syndromes. The epigenetic changes with response to paternal food supply also linked to offspring health. CR at middle and old age provides a significant preventive impact against the development of age-associated diseases.

Effect of different dietary fats on inflammation and glucose intolerance in high fructose and high fat fed experimental animals.

OBJECTIVES: Diet is the major modifiable risk factor for the onset of insulin resistance and its progression into diabetes. In the present study the effect of various dietary fats on inflammatory homeostasis and glucose tolerance is investigated in high fat and high fructose fed mice model. METHODS: C57/BL6J mice were divided into four groups and fed a casein-based diet containing high fructose (45%) and high fat (24%) (clarified butter oil [CBO]; safflower oil [SFFO] and lard oil [LO]) for 120 days; oral glucose tolerance (OGTT), plasma lipid profile and plasma & adipose tissue cytokines levels were compared with the control diet (10% groundnut oil and 59.5% starch) fed animals. RESULTS: The total cholesterol and triglycerides were higher in CBO and LO fed animals with glucose intolerance and increased body weights; liver and white adipose tissue weights were higher in CBO and LO fed animals respectively. CBO feeding increased the plasma (IFN-γ) and adipose tissue cytokines (IFN-γ, IL-10, IL-6 & TNF-α). LO feeding increased plasma IFN-γ, TNF-α and IL-1ß and adipose tissue IL-6. SFFO feeding decreased body weight and tissue cytokines and increased plasma IFN-γ levels without causing impairment in the glucose tolerance. CONCLUSIONS: Consumption of a high fructose and high fat diet which mimic the present-day dietary pattern resulted in altered inflammatory homeostasis and impairment in glucose tolerance in 24% CBO and LO fed animals. The deleterious effects of high fructose feeding were reversed in SFFO fed mice possibly due to the presence of oleic and linoleic acids.

Attenuation of FGF21 signalling might aggravate the impairment of glucose homeostasis during the high sucrose diet induced transition from prediabetes to diabetes in WNIN/GR-Ob rats.

Fibroblast growth factor 21 (FGF21) has emerged as a pleiotropic hormone and is known for its beneficiary roles in the management of diabetes and hyperglycaemia. However, the role of FGF21 during the transition from prediabetes to diabetes still remains unclear. Hence, the present study is aimed to understand the regulation of glucose homeostasis by FGF21 during the transition from prediabetes to diabetes in WNIN/GR-Ob rats. A total of 36 WNIN/GR-Ob obese male rats (28 days old) were divided into control and high sucrose (HS) groups and were fed ad libitum with their respective diets. These groups were sacrificed at different time points (week 1, 6, and 12) and various physical, biochemical, and molecular mediators were assessed to address FGF21 mediated glucose homeostasis. The study results revealed that rats developed impaired glucose tolerance and insulin resistance by exhibiting delayed glucose clearance from circulation, elevated fasting insulin, increased AUC glucose and HOMA-IR scores significantly; thereby rats demonstrated prediabetes by week 6 and diabetes complications by week 12. In line with the above, differential expression of genes attributed to FGF21 mediated glucose homeostasis, i.e., PPARα, FGF21, ß-klotho, PPARγ, Adiponectin, Akt, and UCP1 suggest that the acute insulin sensitizing effect of FGF21 was significantly impaired during prediabetes to diabetes transition. In addition, increased gene and protein expression of FGF21 during the transition compared to controls could be a compensatory response to possibly counteract the metabolic stress imposed by high sucrose diet in WNIN/GR-Ob rats of the experimental group. Findings from the current study emphasize the potential role of FGF21 in glucose homeostasis and its attenuation might aggravate glucose impairment during the transition from prediabetes to diabetes in high sucrose diet induced WNIN/GR-Ob rats.

Strain specific variation underlines the disparity in stress response of rats to calorie dense diets in the pathophysiology of obesity.

Obesity is a multifactorial disorder, caused mainly due to lifestyle changes, and increased consumption of calorie dense diets is not just limited to developed countries anymore. Chronic physiological stress and oxidative stress are known to be implicated in the etiology of obesity. However, the role of stress response towards obesity manifestation in genetically different rat strains is poorly understood. In the current study we have used obesity susceptible & resistant rat models to understand the role of both glucocorticoid and oxidativestress in the pathophysiology of obesity. Upon challenge with calorie dense diets, WNIN showed an increased glucocorticoid stress, resulting in increased oxidative stress; whereas such a phenomenon was not noticed in F-344 and SD. However, there was an increase in the circulatory melatonin levels in calorie dense fed groups of both F-344 and SD animals, which might have contributed to reduced oxidative stress. The molecular switch in the activation of melatonin could be possibly attributed to the genetic differences among these strains. It will be interesting to explore other molecular mechanisms for melatonin regulation, albeit increased corticosterone is implicated in the enhanced production of melatonin.

Maternal Magnesium Restriction Elevates Glucocorticoid Stress and Inflammation in the Placenta and Fetus of WNIN Rat Dams.

Magnesium plays a major role in many vital functions in the body. We reported earlier that maternal magnesium restriction altered body composition, fat metabolism, and insulin resistance in WNIN rat offspring and was associated with increased glucocorticoid stress in the offspring in their later life. We hypothesize that increased glucocorticoid stress and inflammation which originate in Mg restricted rat dams is transmitted through placenta to the fetus and underlie the metabolic disturbances in the later life of the offspring. Female weanling WNIN rats received ad libitum, a control diet (MgC) or the same with 62% restriction of Mg (MgR) for 3 months, and their plasma magnesium, inflammatory cytokines, and corticosterone were determined (n = 6 per group) before mating. Following mating with control males, placentae, and fetuses were collected on gestational day 15 (GD 15) from MgC and MgR dams (eight dams from each group and three samples from each dam) and used to determine the levels of inflammatory cytokines, corticosterone, and expression of relevant genes. MgR placentae and fetuses had higher (than MgC) levels of corticosterone and proinflammatory cytokines. Expression of Hsd11b1 was increased (sixfold, p < 0.05), while that of Hsd11b2 was decreased (0.4-fold, p < 0.05) in MgR (than MgC) placenta, whereas expression of Hsd11b1was increased (3.4-fold, p < 0.05) in MgR fetus. Chronic dietary magnesium restriction in WNIN female rats increased their levels of corticosterone, leptin, and proinflammatory cytokines which appeared to be transmitted through placenta to the fetus and could thus be associated with increased stress, altered body composition, fat metabolism, and insulin resistance in the later life of the offspring.

Differential response of rat strains to obesogenic diets underlines the importance of genetic makeup of an individual towards obesity.

Obesity, a multifactorial disorder, results from a chronic imbalance of energy intake vs. expenditure. Apart from excessive consumption of high calorie diet, genetic predisposition also seems to be equally important for the development of obesity. However, the role of genetic predisposition in the etiology of obesity has not been clearly delineated. The present study addresses this problem by selecting three rat strains (WNIN, F-344, SD) with different genetic backgrounds and exposing them to high calorie diets. Rat strains were fed HF, HS, and HFS diets and assessed for physical, metabolic, biochemical, inflammatory responses, and mRNA expression. Under these conditions: significant increase in body weight, visceral adiposity, oxidative stress and systemic pro-inflammatory status; the hallmarks of central obesity were noticed only in WNIN. Further, they developed altered glucose and lipid homeostasis by exhibiting insulin resistance, impaired glucose tolerance, dyslipidemia and fatty liver condition. The present study demonstrates that WNIN is more prone to develop obesity and associated co-morbidities under high calorie environment. It thus underlines the cumulative role of genetics (nature) and diet (nurture) towards the development of obesity, which is critical for understanding this epidemic and devising new strategies to control and manage this modern malady.

Genetic Relatedness of WNIN and WNIN/Ob with Major Rat Strains in Biomedical Research.

WNIN (Wistar/NIN) is an inbred rat strain maintained at National Institute of Nutrition (NIN) for more than 90 years, and WNIN/Ob is an obese mutant originated from it. To determine their genetic relatedness with major rat strains in biomedical research, they were genotyped at various marker loci. The recently identified markers for albino and hooded mutations which clustered all the known albino rats into a single lineage also included WNIN and WNIN/Ob rats. Genotyping using microsatellite DNA markers and phylogenetic analysis with 49 different rat strains suggested that WNIN shares a common ancestor with many Wistar originated strains. Fst estimates and Fischer's exact test suggest that WNIN rats differed significantly from all other strains tested. WNIN/Ob though shows hyper-leptinemia, like Zucker fatty rat, did not share the Zucker fatty rat mutation. The above analyses suggest WNIN as a highly differentiated rat strain and WNIN/Ob a novel obese mutant evolved from it.

Leptin gene promoter DNA methylation in WNIN obese mutant rats.

BACKGROUND: Obesity has become an epidemic in worldwide population. Leptin gene defect could be one of the causes for obesity. Two mutant obese rats WNIN/Ob and WNIN/GROb, isolated at National Centre for Laboratory Animal Sciences (NCLAS), Hyderabad, India, were found to be leptin resistant. The present study aims to understand the regulatory mechanisms underlying the resistance by promoter DNA methylation of leptin gene in these mutant obese rats. METHODS: Male obese mutant homozygous, carrier and heterozygous rats of WNIN/Ob and WNIN/GROb strain of 6 months old were studied to check the leptin gene expression (RT-PCR) and promoter DNA methylation (MassARRAY Compact system, SEQUENOM) of leptin gene by invivo and insilico approach. RESULTS: Homozygous WNIN/Ob and WNIN/GROb showed significantly higher leptin gene expression compared to carrier and lean counterparts. Leptin gene promoter DNA sequence region was analyzed ranging from transcription start site (TSS) to-550 bp length and found four CpGs in this sequence among them only three CpG loci (-309, -481, -502) were methylated in these WNIN mutant rat phenotypes. CONCLUSION: The increased percentage of methylation in WNIN mutant lean and carrier phenotypes is positively correlated with transcription levels. Thus genetic variation may have effect on methylation percentages and subsequently on the regulation of leptin gene expression which may lead to obesity in these obese mutant rat strains.

Obese locus in WNIN/obese rat maps on chromosome 5 upstream of leptin receptor.

WNIN/Obese (WNIN/Ob) rat a new mutant model of metabolic syndrome was identified in 1996 from an inbred Wistar rat strain, WNIN. So far several papers are published on this model highlighting its physical, biochemical and metabolic traits. WNIN/Ob is leptin resistant with unaltered leptin or its receptor coding sequences--the two well-known candidate genes for obesity. Genotyping analysis of F2 progeny (raised from WNIN/Ob × Fisher--344) in the present study localized the mutation to a recombinant region of 14.15cM on chromosome 5. This was further corroborated by QTL analysis for body weight, which narrowed this region to 4.43 cM with flanking markers D5Rat256 & D5Wox37. Interval mapping of body weight QTL shows that the LOD score peak maps upstream of leptin receptor and shows an additive effect suggesting this as a novel mutation and signifying the model as a valuable resource for studies on obesity and metabolic syndrome.

Effect of maternal vitamin and mineral restrictions on the body fat content and adipocytokine levels of WNIN rat offspring.

BACKGROUND: Intrauterine growth retardation due to maternal under-nutrition increases susceptibility to obesity and insulin resistance. We reported earlier in the offspring of mineral or vitamin restricted rat dams, a high body fat percentage and decreased insulin secretion to glucose challenge. This study determined whether or not central adiposity and altered adipocytokine profile were associated with high body fat content. METHODS: Body fat percentage; glucose, insulin and adipocytokine levels in fasting plasma and fresh weights of epididymal fat pads were determined in the six months old male offspring of Wistar NIN rat dams on chronic 50 percent restriction of vitamins or minerals throughout their growth, gestation, lactation and weaned on to restricted diets or restricted mothers/offspring rehabilitated from different time points. RESULTS: In line with high body fat percent, chronic restriction of vitamins and minerals increased the epididymal fat pad weight. Maternal vitamin restriction decreased plasma adiponectin and increased leptin levels whereas mineral restriction decreased both. Both the treatments did not affect plasma TNF-alpha levels or insulin resistance status (HOMA-IR). Rehabilitation from parturition but not weaning, rescued the changes in the offspring. CONCLUSION: High body fat percentage in the offspring of vitamin restricted or mineral restricted rat dams was associated with increased abdominal adiposity (epididymal fat pad weight) and differential expression of adipocytokines but not insulin resistance. The changes could be mitigated by rehabilitation from birth but not weaning.