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Micronutrient deficiencies, environmental exposures and severe malaria: Risk factors for adverse neurodevelopmental outcomes in Ugandan children

ABSTRACT: Micronutrient deficiencies and environmental exposures have been to known to adversely impact brain and nervous system functions in adults and children worldwide. However, few studies have examined the short and long-term impact of these risk factors on neurodevelopmental outcomes in children in low-income countries, where the effects are likely to be more pronounced due to limited resources for monitoring and insufficient regulations. Biological risk factors of relevance include micronutrient deficiencies such as zinc and exposure to heavy metals such as lead and mercury. Studies have suggested an association between neurodevelopmental impairment and micronutrient deficiency as well as exposure to a number of heavy metals and environmental toxins. Moreover, findings also suggest that risk factors for adverse developmental outcomes that are independently significant may have the potential for causing cumulative increases in adverse effects. In Sub-Saharan Africa, severe malaria is a leading risk factor for long-term neurocognitive impairment in children. Zinc deficiency or exposure to heavy metals could influence risk of severe malaria, modify the risk of neurocognitive impairment in children with severe malaria, or independently affect risk of neurocognitive impairment. Untargeted analyses for potential environmental exposures or metabolomic changes in children with cerebral malaria vs. without cognitive impairment or in children with higher vs. lower cognitive scores, could also identify new risk factors for neurodevelopmental impairment in Ugandan children with cerebral malaria.In our completed study in Kampala, we assessed neurologic and developmental impairment in children with cerebral malaria [CM] or severe malarial anemia [SMA], as compared to health community children from the same extended household as the children with CM or SMA. As an extension of this study, we are interested in determining levels of micronutrients such as zinc in the population, and in addition, determining exposure levels of heavy metals (lead, mercury, copper, manganese etc.) in samples collected from children with severe malaria and community controls. The primary hypotheses of this study is that nutrient deficiencies or exposure to heavy metals influence short and long term neurocognitive outcomes in healthy community children and in children with severe malaria, and that children with cerebral malaria have specific metabolomic changes that relate to long-term neurocognitive impairment. The specific aims of our study are:Aim 1: To determine levels of zinc, heavy metals, and biomarkers associated with inflammation in children presenting with different forms of severe malaria (SM) and in healthy community children (CC). The working hypothesis of this aim is that 1) children with SM will have lower zinc levels compared to CC; 2) children with SM will present with higher toxic metal exposure and higher levels of biomarkers associated with inflammation than CC.Aim 2: To investigate how micronutrient deficiency, toxic metal exposure and inflammatory biomarkers affect short and long term neurodevelopmental outcomes and growth in children with severe malaria and community children (CC).The working hypothesis of this aim is that the lower levels of zinc, and presence of toxic metals in high concentrations will independently contribute to worsening neurodevelopmental outcomes and worsening growth over time in children with severe malaria and in community children. An alternate hypothesis is that micronutrient deficiency, toxic metal exposure and inflammatory states may interact with each other and with severe malaria to produce greater neurodevelopmental impairment, i.e., that the contribution is not independent but interactive.Aim 3: To determine whether the CSF metabolome differs according to level of neurodevelopmental impairment in children with cerebral malaria. The working hypothesis of this aim is that neurodevelopmental impairment in children with cerebral malaria is associated with changes in the CSF metabolome.

ORGANISM(S): Human Homo Sapiens

TISSUE(S): Cerebrospinal Fluid

DISEASE(S): Environmental Exposure,Micronutrient Deficiency

SUBMITTER: Douglas Walker

PROVIDER: ST000877 | MetabolomicsWorkbench | Wed Sep 27 00:00:00 BST 2017

REPOSITORIES: MetabolomicsWorkbench

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Project description:We aimed at finding differently expressed genes in whole blood cells of African children with asymptomatic Plasmodium falciparum infection (A), uncomplicated malaria (U), severe malarial anemia (A) and cerebral malaria (Ce) compared one to another and to healthy children (Co). Understanding malarial immunopathology in the human host represents and enormous challenge for transcriptomic research. In this work, we used microarray and real-time RT-PCR technology to pursue deeper knowledge about the mechanisms underlying this disease in African children. To this end, we investigated the genomic transcriptional profiles in whole blood of healthy children and children with asymptomatic infection, uncomplicated malaria, malaria associated with severe anemia and cerebral malaria and compared them with previously published microarray results. We were able to discriminate between the different presentations of P. falciparum infection using supervised and unsupervised clustering of microarray data and unsupervised double-hierarchical clustering of real-time RT-PCR results of a set of 22 genes known to be expressed in at least one of the principal blood cell lineages. We further found considerable overlap between genes regulated in Kenyan and Gabonese children with symptomatic malaria, in contrast to adults with acute malaria from Cameroon. Different signatures for transcription factor binding sites in promoters of genes either up-regulated in symptomatic disease, specifically up-regulated in uncomplicated malaria or specifically down-regulated in cerebral malaria point out that similar gene expression in each of these clinical presentations is probably a result of common regulation at the transcriptional level. Immunoglobulin production, complement regulation and IFN beta signalling emerged as most discrepant features between uncomplicated malaria and all other investigated presentations, correlating with IRF7 and ISRE binding signatures in the corresponding genes. Down-regulation of several genes in cerebral malaria seems instead to be a response to hypoxia orchestrated by AhRF, GABP and HIF1 transcription factors. ARG1, BPI, CD163, IFI27, HP and TNFAIP6 transcript levels correlated positively with lactatemia and inversely with hemoglobin concentration and should be evaluated as prognostic markers to direct early therapeutic measures and prevent malarial disease evolution and death.

Project description:Heavy metals residue in the natural ecosystem had become one global environmental problem that was eager to solve. Due to the non-biodegradability, organism could deposit excessive heavy metals elements into tissues. Existing literature proposed that prolonged heavy metals enrichment had comprehensive toxicity to multi-organs of vertebrates. However, little research focus on the molecular mechanism for the hepatotoxicity of heavy metal enrichment to Chiroptera. In the present study, ten Hipposideros armiger individuals from Yingde City (YD, relatively pollution-free) and Chunwan City (CW, excessive heavy metals emission) were dissected while environment samples were also obtained. To corroborate the toxicity mechanism of heavy metals to bats liver, multi-omics, pathology and molecular biology methods were performed. Our results showed that more Cd and Pb elements were significantly enriched in bats liver and food sources in the CW group. In addition, prolonged heavy metals accumulation disturbed the hepatic transcription profiling associated with solute carriers family, ribosome pathway, ATP usage and heat shock proteins. Excessive heavy metals enrichment also altered the relative abundance of typical gut microbe taxa to inhibit the tight-junction protein expression. We also found that the levels of superoxide dismutase, glutathione peroxidase and glutathione were decreased while ROS density and malondialdehyde content were elevated after excessive heavy metals enrichment. Besides, hepatic fat accumulation and inflammation injury were also observed under the excessive heavy metals enrichment while the metabolism biomarkers contents were decreased. Therefore, prolonged heavy metals enrichment would induce a series of hepatotoxicity by disturbing the microbes-gut-liver axis and hepatic transcription modes, which could decrease the overall metabolism level in bats. Our study provided protection strategy for biodiversity conservation and raised public attention to environment pollution.

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Micronutrient deficiencies, environmental exposures and severe malaria: Risk factors for adverse neurodevelopmental outcomes in Ugandan children

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