Sun Eun Lee

Risk of childhood undernutrition related to small-for-gestational age and preterm birth in low- and middle-income countries

BACKGROUND Low- and middle-income countries continue to experience a large burden of stunting; 148 million children were estimated to be stunted, around 30-40% of all children in 2011. In many of these countries, foetal growth restriction (FGR) is common, as is subsequent growth faltering in the first 2 years. Although there is agreement that stunting involves both prenatal and postnatal growth failure, the extent to which FGR contributes to stunting and other indicators of nutritional status is uncertain. METHODS Using extant longitudinal birth cohorts (n=19) with data on birthweight, gestational age and child anthropometry (12-60 months), we estimated study-specific and pooled risk estimates of stunting, wasting and underweight by small-for-gestational age (SGA) and preterm birth. RESULTS We grouped children according to four combinations of SGA and gestational age: adequate size-for-gestational age (AGA) and preterm; SGA and term; SGA and preterm; and AGA and term (the reference group). Relative to AGA and term, the OR (95% confidence interval) for stunting associated with AGA and preterm, SGA and term, and SGA and preterm was 1.93 (1.71, 2.18), 2.43 (2.22, 2.66) and 4.51 (3.42, 5.93), respectively. A similar magnitude of risk was also observed for wasting and underweight. Low birthweight was associated with 2.5-3.5-fold higher odds of wasting, stunting and underweight. The population attributable risk for overall SGA for outcomes of childhood stunting and wasting was 20% and 30%, respectively. CONCLUSIONS This analysis estimates that childhood undernutrition may have its origins in the foetal period, suggesting a need to intervene early, ideally during pregnancy, with interventions known to reduce FGR and preterm birth.

Dietary intakes of women during pregnancy in low- and middle-income countries

OBJECTIVE To provide a better understanding of dietary intakes of pregnant women in low- and middle-income countries. DESIGN Systematic review was performed to identify relevant studies which reported nutrient intakes or food consumption of pregnant women in developing countries. Macronutrient and micronutrient intakes were compared by region and the FAO/WHO Estimated Average Requirements. Food consumption was summarized by region. SETTING Developing countries in Africa, Asia, and the Caribbean and Central/South America. SUBJECTS Pregnant women in the second or third trimester of their pregnancies. RESULTS From a total of 1499 retrieved articles, sixty-two relevant studies were analysed. The ranges of mean/median intakes of energy, fat, protein and carbohydrate were relatively higher in women residing in the Caribbean and Central/South America than in Africa and Asia. Percentages of energy from carbohydrate and fat varied inversely across studies in all regions, whereas percentage of energy from protein was relatively stable. Among selected micronutrients, folate and Fe intakes were most frequently below the Estimated Average Requirements, followed by Ca and Zn. Usual dietary patterns were heavily cereal based across regions. CONCLUSIONS Imbalanced macronutrients, inadequate micronutrient intakes and predominantly plant-based diets were common features of the diet of pregnant women in developing countries. Cohesive public health efforts involving improving access to nutrient-rich local foods, micronutrient supplementation and fortification are needed to improve the nutrition of pregnant women in developing countries.

Plasma Proteome Biomarkers of Inflammation in School Aged Children in Nepal

Inflammation is a condition stemming from complex host defense and tissue repair mechanisms, often simply characterized by plasma levels of a single acute reactant. We attempted to identify candidate biomarkers of systemic inflammation within the plasma proteome. We applied quantitative proteomics using isobaric mass tags (iTRAQ) tandem mass spectrometry to quantify proteins in plasma of 500 Nepalese children 6–8 years of age. We evaluated those that co-vary with inflammation, indexed by α-1-acid glycoprotein (AGP), a conventional biomarker of inflammation in population studies. Among 982 proteins quantified in >10% of samples, 99 were strongly associated with AGP at a family-wise error rate of 0.1%. Magnitude and significance of association varied more among proteins positively (n = 41) than negatively associated (n = 58) with AGP. The former included known positive acute phase proteins including C-reactive protein, serum amyloid A, complement components, protease inhibitors, transport proteins with anti-oxidative activity, and numerous unexpected intracellular signaling molecules. Negatively associated proteins exhibited distinct differences in abundance between secretory hepatic proteins involved in transporting or binding lipids, micronutrients (vitamin A and calcium), growth factors and sex hormones, and proteins of largely extra-hepatic origin involved in the formation and metabolic regulation of extracellular matrix. With the same analytical approach and the significance threshold, seventy-two out of the 99 proteins were commonly associated with CRP, an established biomarker of inflammation, suggesting the validity of the identified proteins. Our findings have revealed a vast plasma proteome within a free-living population of children that comprise functional biomarkers of homeostatic and induced host defense, nutrient metabolism and tissue repair, representing a set of plasma proteins that may be used to assess dynamics and extent of inflammation for future clinical and public health application.

A Plasma α-Tocopherome Can Be Identified from Proteins Associated with Vitamin E Status in School-Aged Children of Nepal

BACKGROUND The term vitamin E describes a family of 8 vitamers, 1 of which is α-tocopherol, that is essential for human health. Vitamin E status remains largely unknown in low-income countries because of the complexity and cost of measurement. Quantitative proteomics may offer an approach for identifying plasma proteins for assessing vitamin E status in these populations. OBJECTIVE To improve options for vitamin E status assessment, we sought to detect and quantify a set of plasma proteins associated with α- and γ-tocopherol concentrations in a cohort of 500 rural Nepalese children aged 6-8 y and, based on nutrient-protein associations, to predict the prevalence of vitamin E deficiency (α-tocopherol <12 μmol/L). METHODS Study children were born to mothers enrolled in an earlier antenatal micronutrient trial in Sarlahi District, Nepal. Plasma α- and γ-tocopherol concentrations were measured by high-performance liquid chromatography. Plasma aliquots were depleted of 6 high-abundance proteins, digested with trypsin, labeled with isobaric mass tags, and assessed for relative protein abundance by tandem mass spectrometry. Linear mixed-effects models were used to evaluate the association between α-tocopherol status and relative protein abundance and to predict deficiency. RESULTS We quantified 982 plasma proteins in >10% of all child samples, of which 119 correlated with α-tocopherol (false discovery rate, q < 0.10). Proteins were primarily involved in lipid transport, coagulation, repair, innate host defenses, neural function, and homeostasis. Six proteins [apolipoprotein (apo)C-III; apoB; pyruvate kinase, muscle; forkhead box 04; unc5 homolog C; and regulator of G-protein signaling 8] explained 71% of the variability in plasma α-tocopherol, predicting an in-sample population prevalence of vitamin E deficiency of 51.4% (95% CI: 46.4%, 56.3%) compared with a measured prevalence of 54.8%. Plasma γ-tocopherol was associated with 12 proteins (q < 0.10), 2 of which (apoC-III and Misato 1) explained 20% of its variability. CONCLUSIONS In this undernourished population of children in South Asia, quantitative proteomics identified a large plasma α-tocopherome from which 6 proteins predicted the prevalence of vitamin E deficiency. The findings illustrate that protein biomarkers, once absolutely quantified, can potentially predict micronutrient deficiencies in populations. The maternal micronutrient supplementation trial from which data were derived as a follow-up activity was registered with clinicaltrials.gov as NCT00115271.

The Plasma Proteome Is Associated with Anthropometric Status of Undernourished Nepalese School-Aged Children

Background: Malnutrition affects body growth, size, and composition of children. Yet, few functional biomarkers are known to be associated with childhood morphology. Objective: This cross-sectional study examined associations of anthropometric indicators of height, musculature, and fat mass with plasma proteins by using proteomics in a population cohort of school-aged Nepalese children. Methods: Height, weight, midupper arm circumference (MUAC), triceps and subscapular skinfolds, upper arm muscle area (AMA), and arm fat area (AFA) were assessed in 500 children 6–8 y of age. Height-for-age z scores (HAZs), weight-for-age z scores (WAZs), and body mass index–for-age z scores (BAZs) were derived from the WHO growth reference. Relative protein abundance was quantified by using tandem mass spectrometry. Protein-anthropometry associations were evaluated by linear mixed-effects models and identified as having a false discovery rate (q) <5%. Results: Among 982 proteins, 1, 10, 14, and 17 proteins were associated with BAZ, HAZ, MUAC, and AMA, respectively (q < 0.05). Insulin-like growth factor (IGF)-I, 2 IGF-binding proteins, and carnosinase-1 were associated with both HAZ and AMA. Proteins involved in nutrient transport, activation of innate immunity, and bone mineralization were associated with HAZ. Several extracellular matrix proteins were positively associated with AMA alone. The proteomes of MUAC and AMA substantially overlapped, whereas no proteins were associated with AFA or triceps and subscapular skinfolds. Myosin light-chain kinase, possibly reflecting leakage from muscle, was inversely associated with BAZ. The proteome of WAZ was the largest (n = 33) and most comprehensive, including proteins involved in neural development and oxidative stress response, among others. Conclusions: Plasma proteomics confirmed known biomarkers of childhood growth and revealed novel proteins associated with lean mass in chronically undernourished children. Identified proteins may serve as candidates for assessing growth and nutritional status of children in similar undernourished settings. The antenatal micronutrient supplementation trial yielding the study cohort of children was registered at clinicaltrials.gov as NCT00115271.

Biological Systems of Vitamin K: A Plasma Nutriproteomics Study of Subclinical Vitamin K Deficiency in 500 Nepalese Children

Abstract Vitamin K (VK) is a fat-soluble vitamin whose deficiency disrupts coagulation and may disturb bone and cardiovascular health. However, the scale and systems affected by VK deficiency in pediatric populations remains unclear. We conducted a study of the plasma proteome of 500 Nepalese children 6–8 years of age (male/female ratio = 0.99) to identify proteins associated with VK status. We measured the concentrations of plasma lipids and protein induced by VK absence-II (PIVKA-II) and correlated relative abundance of proteins quantified by mass spectrometry with PIVKA-II. VK deficiency (PIVKA-II >2 μg/L) was associated with a higher abundance of low-density lipoproteins, total cholesterol, and triglyceride concentrations (p < 0.01). Among 978 proteins observed in >10% of the children, five proteins were associated with PIVKA-II and seven proteins were differentially abundant between VK deficient versus sufficient children, including coagulation factor-II, hemoglobin, and vascular endothelial cadherin, passing a false discovery rate (FDR) threshold of 10% (q < 0.10). Among 27 proteins associated with PIVKA-II or VK deficiency at a less stringent FDR (q < 0.20), a network comprised of hemoglobin subunits and erythrocyte anti-oxidative enzymes were highly and positively correlated each other (all r > 0.7). Untargeted proteomics offers a novel systems approach to elucidating biological processes of coagulation, vascularization, and erythrocyte oxidative stress related to VK status. The results may help elucidate subclinical metabolic disturbances related to VK deficiency in populations.

Plasma proteins associated with circulating carotenoids in Nepalese school-aged children

Carotenoids are naturally occurring pigments that function as vitamin A precursors, antioxidants, anti-inflammatory agents or biomarkers of recent vegetable and fruit intake, and are thus important for population health and nutritional assessment. An assay approach that measures proteins could be more technologically feasible than chromatography, thus enabling more frequent carotenoid status assessment. We explored associations between proteomic biomarkers and concentrations of 6 common dietary carotenoids (α-carotene, β-carotene, lutein/zeaxanthin, β-cryptoxanthin, and lycopene) in plasma from 500 6–8 year old Nepalese children. Samples were depleted of 6 high-abundance proteins. Plasma proteins were quantified using tandem mass spectrometry and expressed as relative abundance. Linear mixed effects models were used to determine the carotenoid:protein associations, accepting a false discovery rate of q < 0.10. We quantified 982 plasma proteins in >10% of all child samples. Among these, relative abundance of 4 were associated with β-carotene, 11 with lutein/zeaxanthin and 51 with β-cryptoxanthin. Carotenoid-associated proteins are notably involved in lipid and vitamin A transport, antioxidant function and anti-inflammatory processes. No protein biomarkers met criteria for association with α-carotene or lycopene. Plasma proteomics may offer an approach to assess functional biomarkers of carotenoid status, intake and biological function for public health application. Original maternal micronutrient trial from which data were derived as a follow-up activity was registered at ClinicalTrials.gov: NCT00115271.

Plasma Selenium Protein P Isoform 1 (SEPP1): A Predictor of Selenium Status in Nepalese Children Detected by Plasma Proteomics.

Selenium deficiency or excess may have public health consequences, yet selenium status is infrequently characterized in populations, perhaps due to challenges in methodology. We are seeking to identify plasma proteins, using proteomics discovery and validation approaches, to serve as proxies for micronutrient status, including selenium, which may in the future be more readily assessed by robust, affordable field methods. In a sample of rural Nepalese children 6 - 8 years old (n = 500), the prevalence of selenium deficiency was 13.6 and 60.9 % at plasma selenium concentrations < 0.60 and < 0.89 µmol/L, respectively, assessed by atomic absorption spectroscopy. Relative abundance of selenoprotein P isoform 1 (SEPP1), glutathione reductase-3, and apolipoprotein A2 from discovery-based experiments was correlated with plasma selenium with a false discovery rate < 10 % (i. e., q < 0.10), all with p < 0.001. In linear mixed effects regression models to predict plasma selenium, only SEPP1 was significant (R2 = 0.63), estimating 8.2 % (95 % CI: 3.9 - 12.6) and 65.5(61.4 - 69.7)% of the in-sample population as deficient at each respective cut-off. Targeted quantification of SEPP1 in a preliminary series of specimens (n = 19) as a validation of the discovery approach revealed a high correlation with plasma selenium (r = 0.757, p = 0.0002). Plasma proteomics can identify valid plasma protein indicators of micronutrient status, as shown with selenium, comprising a step toward making population assessment of selenium status in vulnerable groups more accessible.

Novel Plasma Proteins in Nepalese School-aged Children are Associated with a Small Head Size at Birth

Fetal growth restriction increases the risk of poor childhood growth and development and chronic disease in adulthood. Yet, little is known about biological pathways that mediate the long-lasting effects of suboptimal intrauterine growth. We explored the plasma proteome in a cohort of 500 Nepalese children 6–8 years of age to identify plasma proteins associated with multiple anthropometric size indicators at birth. Among 982 proteins analyzed, no proteins differed by birth weight, length, or weight-for-length indicators. However, 25 proteins were differentially abundant in children with a small vs normal head circumference at birth (<−2 vs. ≥−2 z-scores of the WHO growth standards). Angiopoietin-like 6 was 19.4% more abundant and the other 24 proteins were 7–21% less abundant in children with a small vs normal head circumference at birth, adjusted for potential confounders. The less abundant proteins included actins, actin filament organizing proteins (α-actinin, talin, filamin, cofilin, profilin, and vinculin), proteins involved in muscle contraction, and glycolytic enzymes, which were all positively correlated with each other. A novel cluster of childhood plasma proteins involved in angiogenesis and cytoskeleton dynamics was associated with a small head size at birth. The prognostic value of an altered proteomic phenotype remains to be investigated.