Gut Microbiota Composition in Hispanic and Non-Hispanic Children.
Condition: Obesity
MeSH terms: Obesity
Study type: Observational

Summary: 
      The human gastrointestinal (GI) tract is filled with millions of bacteria that can affect our
      health. These bacteria are linked with our overall health including obesity risk. In the
      United States the Hispanic population is one of the ethnic groups at higher risk of
      developing obesity. In this study the team will investigate differences in the GI bacterial
      composition between Hispanic and Caucasian children, and potentially demonstrate a
      correlation between the composition of metagenome and a higher risk to develop obesity. This
      will be done by collecting stool samples and comparing the bacteria found in the stool of
      Hispanic children (with and without obesity) and Caucasian children (with and without
      obesity.
    

Detailed description: 
      I. SPECIFIC AIMS There are a vast number of microbes in the human gastrointestinal tract (GI)
      including bacterial, fungal and protozoal microorganisms which all together make our
      microbiome. Over the last years evidence has shown that the GI microbiome is linked with our
      overall health including obesity risk. The GI microbiota can influence both sides of the
      energy balance that includes factors influencing energy utilization from the diet and factors
      that play a role in the regulation of energy expenditure and storage by influencing host
      genes (1, 2). Studies of demonstrated that overweight and obesity rates are among the highest
      for Hispanic children in the United States. It is estimated that in the US 47% of Hispanic
      children are overweight and 31% have obesity, compared to 35% and 21% respectively for
      Caucasian non-Hispanic children. Literature has shown environment factors are associated with
      childhood obesity in Hispanic children including: parental influences, screen time, physical
      activity behavior, socioeconomic status/food security, and sleep duration (3,4). Thus far
      there have been no studies having investigated if there are significant differences in the
      gut microbiome of Hispanic children; moreover, whether these differences (taxonomy or gene
      expression) puts them at higher risk to develop obesity compared other ethnic groups.

      The investigators predict there are significant GI microbiome differences between Caucasian
      non-Hispanic children and Hispanic Children.

      Aim: Confirm differences in microbiome between Caucasian non-Hispanic children (with and
      without obesity) and Hispanic children (with and without obesity) in this pilot study.

      Hypothesis: Hispanic children will have a lower fecal bacterial diversity compared to
      Caucasian non-Hispanic children that is associated with more overall adiposity and impaired
      glucose homeostasis determined by:

      A) Next generation metagenomic "whole genome/shotgun" sequencing of DNA from fecal samples of
      cohorts which includes Hispanic children with obesity, Hispanic children without obesity,
      Caucasian non-Hispanic children with obesity and Caucasian non-Hispanic children without
      obesity.

      B) Bioinformatics computational analysis comparing the four groups to determine beta
      diversity (relative taxonomic) abundance.

      II. BACKGROUND AND SIGNIFICANCE Obesity is a serious health risk in the United States. The
      prevalence of childhood obesity has increased over the last two decades. According the U.S.
      Department of health and Human Services, recent date showed that the prevalence of obesity
      higher among youth aged 6-11 year and adolescents aged 12-19 years compared with children
      aged 2-5 years of age. The Hispanic population is among the most affected ethnic groups in
      the United States. Approximately 47% of Hispanic children are overweight and 31% have
      obesity. Multiple factors have been found to play a role in the development of childhood
      obesity in Hispanic children, including: parental influences, screen time, physical activity
      behavior, socioeconomic status/food security, and sleep duration.

      Over the last few years there has been a research interest in understanding the development
      and pathogenesis of obesity. Recent studies have found that the gut microbiota plays in an
      important role in the triggering and the development on obesity. The GI microbiota can
      influence both sides of the energy balance that includes factors influencing energy
      utilization from the diet and factors that play a role in the regulation of energy
      expenditure and storage by influencing host genes. In a study by Hou, they evaluated the 16S
      rRNA gene, the enterotypes and quantity of gut microbiota among obese children and a healthy
      control cohort. In this study they found that the composition of the gut microbiota showed
      significant differences between obese children and healthy controls. The results indicated
      that the phyla of Firmicutes and Bacteroidetes were the predominant fecal microbiome in both
      cohorts but the relative abundance ratio of Firmicutes and Bacteroidetes (F/B) in the obese
      cohort was significantly higher than that in the healthy controls. Firmicutes are associated
      with genes involved in carbohydrate catabolism and is rich in obese individuals, while
      Bacteroidetes are linked with diminished body mass.

      At this time there have been no studies that have investigated if there are significant
      differences in the gut microbiome of Hispanic children; moreover, whether these differences
      (taxonomy or gene expression) puts them at higher risk to develop obesity compared other
      ethnic groups. The study team feels it is important to identify possible microbiome
      differences in the Hispanic population that may put them at a higher risk of developing
      childhood obesity.

      III. RESEARCH DESIGN AND METHODS INCLUDING STATISTICAL ANALYSIS Study Subjects/Experimental
      Design The investigators will recruit and enroll 4 cohorts including 6 Hispanic children with
      obesity, 6 Hispanic children without obesity, 6 Caucasian non-Hispanic children with obesity
      and 6 Caucasian non-Hispanic children without obesity. Obesity will be defined as a BMI >95%.
      Enrollment age will be between 6-12 years of age. The investigators will obtain baseline
      characteristics at the time of enrollment, including anthropometric measures (weight, length,
      BMI), dietary history (including 24 hour recall diary and a food frequency questionnaire),
      and physical activity history (Physical activity questionnaire). The investigators will
      obtain medication history, including history of use antibiotics, steroids and probiotics.

      Dietary and Physical activity measurement At fecal collection, investigators will obtain
      dietary information for the patient using a 30-food item food frequency questionnaire and a
      24-hour food recall diary. Diet records will be analyzed using the Nutrient Data System for
      Research software (Minneapolis, MN). The investigators will determine intake of macro- and
      micronutrient intake as well as patterns of dietary intake using the latent class
      (person-centered approach) as well as factor (data-based approach) analyses.

      The investigators will collect physical activity data on the patient using the Physical
      Activity Questionnaire for Older Children (PAQ-C) and will analyze with Spearman correlation
      coefficients. Clinical data management will be the responsibility of the principal
      investigator and GI fellow/co-investigator and will use a secure database, REDCap, through
      Nemours' REDCap system.

      Fecal Sample Collection With permission from the parent/guardian, stool collected in a
      sterile container will be brought within 12 hours of defecation from home or the outpatient
      clinic to a separate clinical laboratory where feces will be collected through use of
      FLOQswab brush x 3 (Copan Diagnostics, Murrieta, CA) The swabs will be pre-labeled with a
      de-identified code reflecting patient number, sample number, and date and the sample will be
      placed into dry ice then transferred to a -80 degrees Celsius freezer until retrieval by the
      research staff for transfer to CHOP Microbiome Center.

      Bacterial DNA Isolation DNA will be extracted from samples using the DNeasy PowerSoil kit
      using the manufacturer's instructions (Qiagen, Germantown, MD). Shotgun libraries will be
      generated from 1 ng of DNA using the NexteraXT kit (Illumina, San Diego, CA, USA). Libraries
      will be sequenced on an Illumina HiSeq 2500 using 2x125bp chemistry in High Output mode.

      Bioinformatics processing and statistical analysis Differences in weight gain, HgbA1c,
      physical activity associated with nutritional diet records or other outcomes will be assessed
      using t-test or Mann Whitney U test, adjusting for covariates. The relationship between
      nutrition records and outcomes will be further examined using mixed effects models, adjusting
      for the effect of key physical activity or dietary variables.

      FASTQ files will be analyzed using an established computational pipeline developed at
      Nemours.
    

Intervention name(s): Fecal Sample Collection; Physical Activity Questionnaire; Food Frequency Questionnaire; 24-hour dietary recall diary
Intervention type(s): Other; Other; Other; Other
Intervention description(s): With permission from the parent/guardian, stool collected in a sterile container will be brought within 12 hours of defecation from home or the outpatient clinic to a separate clinical laboratory where feces will be collected through use of FLOQswab brush x 3 (Copan Diagnostics, Murrieta, CA) The swabs will be pre-labeled with a de-identified code reflecting patient number, sample number, and date and the sample will be placed into dry ice then transferred to a -80 degrees Celsius freezer until retrieval by the research staff for transfer to CHOP Microbiome Center.; At the initial encounter the co-investigator Dr. David Garcia, who is a certified Spanish translator will complete the Physical Activity Questionnaire (Physical Activity Questionnaire for Older Children) with the subject and parent.; At the initial encounter the co-investigator Dr. David Garcia, who is a certified Spanish translator will complete the Food Frequency Questionnaire with the subject and parent.; At the initial encounter the co-investigator Dr. David Garcia, who is a certified Spanish translator will complete the 24-hour dietary recall diary with the subject and parent.
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The investigators will recruit and enroll 4 cohorts including 6 Hispanic children with
        obesity, 6 Hispanic children without obesity, 6 Caucasian non-Hispanic children with
        obesity and 6 Caucasian non-Hispanic children without obesity. Obesity will be defined as a
        BMI >95%. Enrollment age will be between 6-12 years of age.
      
Biospecimen description: 
      One time fecal sample. Nucleic acid preservation is non-human organisms only.
    
Keywords: Gut Microbiome