Sarah N. Taylor, MD and Carol L Wagner, MD Department of Pediatrics Preterm Infant Gut Permeability Differs By Human Milk versus Formula Exposure Sarah N. Taylor, MD and Carol L Wagner, MD Department of Pediatrics

Preterm Infant Gut Infants born as early as 23 weeks gestation (37-41 weeks is full term) Fetal intestine length doubles from 25 to 40 weeks gestation Therefore, this now occurs in the extra-uterine environment

Continuum of Gut Development and Maturation Amniotic Fluid Human Milk Phase V Phase IV Phase III Phase II Phase I Fetal Development Birth Adapted from Wagner CL et al; Clinic Rev Allerg Immunol 2008

Preterm Infant Feeding Must nourish infant Intravenous nutrition available but associated with infection and damage to liver Feeding the immature gut then required Formula (cow’s milk-based) associated with damage to the gut and mortality Therefore, breastmilk (mother’s milk) is the gold standard Also have donor human milk Donated from screened donors and then pasteurized like cow’s milk Tested to have no growth of bacteria

Intestinal Permeability Measurement Sugar Absorption Tests Lactulose Paracellular absorption Mannitol Intracellular absorption Provide standard doses Similar distribution and renal excretion Measure ratio in urine https://www.linkedin.com/pulse/how-intense-exercise-causes-leaky-gut-probiotics-athletic-jamie-dixon

Preterm Infant Intestinal Permeability by Feeding Type Infants fed majority of feeds as human milk (minimal formula intake) have significantly lower intestinal permeability than those fed minimal/none human milk (majority or all formula feedings) Taylor SN et al 2008

Current Study Preterm infant human milk diet requires fortification Fortifier choices Two are concentrated formula (cow’s milk base) One is concentrated donor milk (complete human milk diet) What is the difference in intestinal permeability between a complete human milk diet and a mixed human milk/cow’s milk fortifier diet?

First Days of Human milk feeds Study Conduction Birth Feed Initiation Enrollment Postnatal 1-3 d First Days of Human milk feeds Visit 1 Postnatal 2-4 d Pre-fortification (pre- intervention) Visit 2 Postnatal 6-8 d Post-fortification (post-intervention) Visit 3 Postnatal 13-15 d Full feeds Visit 4 Postnatal 20-22 d

Intestinal Permeability Gut Microbiota Feeding Type Intestinal Permeability Gut Microbiota Vaginal or cesarean section delivery Gestational age at birth <27, 27-30, 30-32 weeks Postnatal days Antibiotic exposure

Mother’s milk fed more Likely to be Type 2 or 3 Cong X et al 2016

Gregory KE et al 2016

Microbiota Comparisons By feeding type (3) Over time between groups and within groups By degree of prematurity at birth <27, 27-30, 30-32 weeks Hypotheses: Microbiota diversity will increase over time Infants receiving human milk only diet will demonstrate microbiota more similar to term, breastfed infant Higher bifidobacterium bifidum Lower proteobacteria

Expertise Needed A few examples Analysis of how many samples? Collecting 792 (1 at each of 4 time points for 198 infants) Opportunities in metagenomics compared to 16S sequencing? Methods to optimize identification of bifidobacterium?