Project description:<p>The PROVIDE study (Dhaka, Bangladesh) is a randomized clinical trial platform which evaluated the efficacy of delayed-dose oral rotavirus vaccine as well as the benefit of an injectable polio vaccine replacing one dose of oral polio vaccine. This rigorous infrastructure supported the additional examination of hypotheses of vaccine underperformance. Primary and secondary efficacy and immunogenicity measures for rotavirus and polio vaccines were measured, as well as the impact of maternal and childhood malnutrition, environmental enteropathy, and additional exploratory variables.</p> <p>This study has been conducted to test the role of epigenetics in malnutrition, specifically the genome-wide role of histone modifications, which are known to provide a precise signature of metabolic state and immune system function.</p>
Project description:The thymus is one of the most affected organs during malnutrition, exhibiting atrophy and thymocyte depletion, characteristics that are also observed in several infectious diseases. The detrimental effects of malnutrition on immune responses to pathogens have long been recognized and it is considered a main risk factor for various infectious diseases, including visceral leishmaniasis (VL). However, the thymus has been barely studied during malnutrition and Leishmania infantum infection association. Protein malnutrition modifies intrathymic communication in L. infantum infected BALB/c mice by altering the abundance of proteins secreted to the thymic interstitial fluid (IF). We identified and compared protein abundance in the thymic IF samples from BALB/c mice that were fed with control protein (14%, CP) or low protein (4%, LP) isocaloric diets, followed by infection with L. infantum. By means of a quantitative proteomics approach using iTRAQ we identified 280 proteins of which 81% were reported as secreted by exosomes and 42% were previously described as secreted by thymic epithelial cells. LP-infected (LPi) animals showed a significant decrease in exosomal proteins, suggesting that exosomal carrier system is dysregulated in malnourished animals. LPi mice also exhibited an increase in the relative abundance of proteins involved in lipid metabolism and tricarboxylic acid cycle, suggestive of a non-proliferative microenvironment. Accordingly, flow cytometry analysis revealed that protein malnutrition decreases the proliferation of single positive and double positive T cells. Proteins engaged in glycolysis, protein ubiquitination and mRNA processing were significantly decreased. In addition, a significant decrease in the abundance of galectin-1 and increase of plasminogen were observed in malnourished animals. Together, the reduced cortical area, decreased proliferation, increased abundance of lipid- and tricarboxylic acid cycle-related proteins, and altered abundance of galectin-1 and plasminogen indicate a dysfunctional thymic microenvironment, where T cell migration, proliferation and maturation are compromised, contributing for the thymic atrophy observed in malnourished animals. All these alterations affect the control of the local and systemic infection, resulting in an impaired response to L. infantum infection.
Project description:A slower transmethylation of one-carbon substrates in the edematous form of severe acute malnutrition (ESAM) suggests that downstream aberrations in DNA methylation could drive differences in acute pathogenesis between ESAM and non-edematous malnutrition (NESAM). Here, we integrate genome-wide assessments of DNA methylation with corresponding gene expression profiles and sequence variation to show that relative to NESAM, acute ESAM is characterized by significant hypomethylation at 99% of differentially methylated loci in two SAM cohorts, whereas recovered adults show no significant differences in methylation. Hypomethylated loci correlate with both up- and down-regulation of proximal genes, which are associated with the clinical sub-phenotypes of kwashiorkor and enriched for GWAS hits linked to over-nutrition, including fatty liver and diabetes. Methylation at these loci also appears to be influenced by nearby genetic variation in a manner that varies with nutritional status. Our findings implicate epigenetic and genetic variation in ESAM pathophysiology and support methyl-group supplementation in ESAM management.
Project description:Protein malnutrition promotes hepatic steatosis, decreases insulin-like growth factor (IGF)-I production, and retards growth. In order to identify new molecules involved in such changes, we conducted DNA microarray analysis for liver samples of rats fed isoenergetic low protein diet for 8 hours, and identified fibroblast growth factor 21 (Fgf21) as one of the most strongly up-regulated genes under conditions of acute protein malnutrition (P<0.05, FDR<0.001). In addition, amino acid deprivation from the culture media increased Fgf21 mRNA levels in rat liver-derived RL-34 cells (P<0.01). Thus, it was suggested that amino acid limitation directly increases Fgf21 expression. FGF21 is a polypeptide hormone that regulates glucose and lipid metabolism. Using transgenic mice, FGF21 has also been shown to promote a growth hormone-resistant state and suppress IGF-I. Therefore, to further determine whether the up-regulation of Fgf21 under protein malnutrition causes hepatic steatosis and growth retardation following decrease in IGF-I, we fed isoenergetic low protein diet to Fgf21-knockout (KO) mice. Fgf21-KO did not rescue growth retardation and reduced plasma IGF-I concentration of mice fed the low-protein diet. Meanwhile, Fgf21-KO mice showed greater epididymal white adipose tissue weight as well as hepatic triglyceride and cholesterol levels under protein malnutrition (P<0.05). Taken together, we showed that protein deprivation directly increases Fgf21 expression. However, growth retardation and decreased IGF-I were not mediated by increased FGF21 expression under protein malnutrition. Furthermore, up-regulated FGF21 rather appears to have a protective effect against obesity and hepatic steatosis in protein malnourished animals. Livers of rats from 2 groups (control (15P) or low-protain (5P) diet fed groups), total of 6 samples (3 replicates for each group) were analyzed.
Project description:Protein malnutrition promotes hepatic steatosis, decreases insulin-like growth factor (IGF)-I production, and retards growth. In order to identify new molecules involved in such changes, we conducted DNA microarray analysis for liver samples of rats fed isoenergetic low protein diet for 8 hours, and identified fibroblast growth factor 21 (Fgf21) as one of the most strongly up-regulated genes under conditions of acute protein malnutrition (P<0.05, FDR<0.001). In addition, amino acid deprivation from the culture media increased Fgf21 mRNA levels in rat liver-derived RL-34 cells (P<0.01). Thus, it was suggested that amino acid limitation directly increases Fgf21 expression. FGF21 is a polypeptide hormone that regulates glucose and lipid metabolism. Using transgenic mice, FGF21 has also been shown to promote a growth hormone-resistant state and suppress IGF-I. Therefore, to further determine whether the up-regulation of Fgf21 under protein malnutrition causes hepatic steatosis and growth retardation following decrease in IGF-I, we fed isoenergetic low protein diet to Fgf21-knockout (KO) mice. Fgf21-KO did not rescue growth retardation and reduced plasma IGF-I concentration of mice fed the low-protein diet. Meanwhile, Fgf21-KO mice showed greater epididymal white adipose tissue weight as well as hepatic triglyceride and cholesterol levels under protein malnutrition (P<0.05). Taken together, we showed that protein deprivation directly increases Fgf21 expression. However, growth retardation and decreased IGF-I were not mediated by increased FGF21 expression under protein malnutrition. Furthermore, up-regulated FGF21 rather appears to have a protective effect against obesity and hepatic steatosis in protein malnourished animals.
Project description:Severe malnutrition in young children is associated with signs of hepatic dysfunction such as steatosis and hypoalbuminemia, but its etiology is unknown. To investigate the underlying mechanisms of hepatic dysfunction we used a rat model of malnutrition by placing weanling rats on a low protein or control diet (5% or 20% of calories from protein, respectively) for four weeks. Low protein diet-fed rats developed hypoalbuminemia and severe hepatic steatosis, consistent with the human phenotype. Hepatic peroxisome content was decreased and metabolomic analysis indicated impaired peroxisomal function. Loss of peroxisomes was followed by accumulation of dysfunctional mitochondria and decreased hepatic ATP levels. Fenofibrate supplementation restored hepatic peroxisome abundance and increased mitochondrial fatty acid β-oxidation capacity, resulting in reduced steatosis and normalization of ATP and plasma albumin levels. These findings provide important insight into the metabolic disturbances associated with malnutrition and have potentially profound clinical consequences with respect to the management of malnourished children worldwide.