Parenteral lipid emulsions in the preterm infant: current issues and controversies

Parenteral lipid emulsions are a necessary component of nutrition for extremely low gestational age newborns until adequate levels of enteral intake are established. Historically, Intralipid, a 100% soybean oil emulsion, has filled this role. Newer multicomponent lipid emulsions containing a mixture of other oils, including olive oil and fish oil, are now available as options, although the regulatory approval for use in neonates varies worldwide. When dosed at currently published recommendations, each of these lipid emulsions meets total fat and energy requirements without a risk of essential fatty acid deficiency. Thus, when choosing which lipid emulsion to provide, the answer must be based on the metabolic differences induced as a result of these fatty acid-rich emulsions and whether the emulsions provide a health advantage or pose a health risk. The questions of induced fatty acid profiles, health benefit and health risk are discussed sequentially for multicomponent lipid emulsions. Despite the growing acceptance of multicomponent lipid emulsions, there is concern regarding changes in blood fatty acid levels and potential health risk without strong evidence of benefit. There remains no ideal parenteral lipid emulsion option for the preterm infant. Standardising future animal and human studies in lipid delivery with the inclusion of lipid metabolism data will iteratively provide answers to inform the optimal lipid emulsion for the preterm infant.

Reconsidering fear of birth: Language matters

Interest in fear of childbirth has grown exponentially since the 1980s, but the landscape of birth has shifted considerably since then, with evolving feminism; moving from a patriarchal environment in a biomedical model of care to a holistic model which recognizes the birth and sexuality rights of women and birthing people. Distinguishing the spectrum of fear from low to high and severe is important rather than aggregating all individuals with fear of childbirth. However, the terms 'fear of childbirth' and 'tocophobia' have been used interchangeably. In this paper we urge clinicians to use the term 'tocophobia' with caution since it may be construed negatively and there is a limited understanding of the underpinning aetiology of tocophobia. Furthermore, using the label may be disempowering for women and birthing people making decisions about their birth. Further research is warranted to better understand the experience, refine and define the issue and meet the individual needs of people with fear of childbirth and tocophobia.

Impact of Long-chain Polyunsaturated Fatty Acids on Hyperoxia-Induced Lung Injury in Neonatal Murine Model

Objectives

Reduced levels of long chain-polyunsaturated fatty acids (LCPUFAs) in preterm infants are associated with several neonatal morbidities, including bronchopulmonary dysplasia (BPD). We hypothesized that LCPUFA supplementation would attenuate hyperoxia-induced lung injury in a neonatal mouse model, and we tested our hypothesis in 40%O2-induced-lung injury in neonatal murine model.

Methods

C57BL/6 WT dams were allowed to deliver naturally, and pups were randomized within 12 hours of birth to either hyperoxia (H, 40% O2) or room air (RA) for 10 days. To study the effect of LCPUFAs on hyperoxia-induced lung injury, the pups were randomized to the following groups: 1) RA (vehicle), 2) H (vehicle), 3) H + AA (120mg/kg/day), 4) H + DHA (60mg/kg/day), and 5) H + AA: DHA at 120mg/kg/day and 60mg/kg/day, respectively, maintaining a 2:1 ratio. Mice were gavage fed once daily 50 ul/g body weight from day 1–9. On day 10, the mice were sacrificed, and the lungs were removed for morphometric analyses. Mean Linear Intercept (MLI), Mean Septal Thickness (MST), and Radial Alveolar Count (RAC) were quantified and analyzed using R software and data was shown as mean ± SD.

Results

Compared to RA group, mice in hyperoxia groups showed a significant increase in MLI intercept (RA vs H = 47.75 ± 2.02 vs 56.24 ± 5.54, p < 0.01) and MST (RA vs H = 7.33 ± 0.45 vs 7.88 ± 0.70, p < 0.01), and a significant decrease in RAC (RA vs H = 12.93 ± 0.82 vs 10.26 ± 1, p < 0.01). Compared to H alone, AA: DHA resulted in a significant reduction in hyperoxia-induced MST (H vs H + AA: DHA = 8.70 ± 0.44 vs 6.94 ± 0.74, p < 0.001) and improved hyperoxia-induced reduction in RAC (H vs H + AA: DHA = 9.7 ± 0.9 vs 12.0 ± 1.4, p < 0.001). Noteworthy, while AA decreased hyperoxia-induced MST (H vs H + AA = 8.7 ± 0.4 vs 6.9 ± 0.6, p < 0.001), it significantly increased MLI (H vs H + AA = 58.76 ± 5.9 vs 71.19 ± 6.1, p < 0.001).

Conclusions

We reproduced lung injury in a neonatal murine model using 40% O2 and showed a significant increase in MLI, MST, and decreased RAC. The data also demonstrate that LCPUFAs acts distinctively, and specific fatty acids alone or in combination have contrasting effects. Whether the observed changes are also associated with the inflammatory response needs to be investigated further to better understand the impact of LCPUFAs in hyperoxia-induced lung injury and inflammation.

Funding Sources

Charles H. and Judy H. Family Infant Health Research Program.

Human Milk Hormone Intake in the First Month of Life and Physical Growth Outcomes in Preterm Infants

CONTEXT

Human milk contains hormones that regulate metabolism. Extrauterine growth restriction remains common among preterm infants, but the effect of ingesting milk hormones on preterm infant growth is poorly understood.

OBJECTIVE

To quantify associations of longitudinal exposure to leptin, adiponectin, and insulin in milk with physical growth of preterm infants.

DESIGN/METHODS

In 50 preterm neonates (median gestational age 29.4 weeks), we sampled maternal milk on day-of-life 7, 14, 21, and 28 and measured hormone levels in whole milk by ELISA. Milk leptin levels were available for a subset of 18 infants. We calculated milk hormone doses by multiplying the hormone level by the milk volume ingested on each day and estimated the area under the curve (AUC) to reflect longitudinal exposure. We analyzed associations of milk hormone exposure with growth outcomes in generalized estimated equations.

MAIN OUTCOME MEASURES

Weight gain velocity and z-scores in weight, length, head circumference, and body mass index at 36 weeks' postmenstrual age (PMA).

RESULTS

Higher leptin intake was associated with greater weight gain (2.17g/kg/day [95% CI, 1.31, 3.02]) and weight z-score at 36 weeks' PMA (0.30 [0.08, 0.53] higher z-score per tertile). Higher adiponectin intake was associated with greater length z-score (0.41 [0.13, 0.69]), however, this association was nullified after adjustment of protein and calorie intake. Higher adiponectin was associated with smaller head circumference z-score (-0.36 [-0.64, -0.07]). Insulin was not associated with growth outcomes.

CONCLUSIONS

Milk leptin and adiponectin exposures may affect growth of preterm infants. The long-term effects of milk hormones warrant further investigation.

Multi-kingdom ecological drivers of microbiota assembly in preterm infants

The gut microbiota of preterm infants develops predictably1-7, with pioneer species colonizing the gut after birth, followed by an ordered succession of microorganisms. The gut microbiota is vital to the health of preterm infants8,9, but the forces that shape these predictable dynamics of microbiome assembly are unknown. The environment, the host and interactions between microorganisms all potentially shape the dynamics of the microbiota, but in such a complex ecosystem, identifying the specific role of any individual factor is challenging10-14. Here we use multi-kingdom absolute abundance quantification, ecological modelling and experimental validation to address this challenge. We quantify the absolute dynamics of bacteria, fungi and archaea in a longitudinal cohort of 178 preterm infants. We uncover microbial blooms and extinctions, and show that there is an inverse correlation between bacterial and fungal loads in the infant gut. We infer computationally and demonstrate experimentally in vitro and in vivo that predictable assembly dynamics may be driven by directed, context-dependent interactions between specific microorganisms. Mirroring the dynamics of macroscopic ecosystems15-17, a late-arriving member of the microbiome, Klebsiella, exploits the pioneer microorganism, Staphylococcus, to gain a foothold within the gut. Notably, we find that interactions between different kingdoms can influence assembly, with a single fungal species-Candida albicans-inhibiting multiple dominant genera of gut bacteria. Our work reveals the centrality of simple microbe-microbe interactions in shaping host-associated microbiota, which is critical both for our understanding of microbiota ecology and for targeted microbiota interventions.

Evaluation of the Neonatal Sequential Organ Failure Assessment and Mortality Risk in Preterm Infants With Late-Onset Infection

IMPORTANCE

Infection in neonates remains a substantial problem. Advances for this population are hindered by the absence of a consensus definition for sepsis. In adults, the Sequential Organ Failure Assessment (SOFA) operationalizes mortality risk with infection and defines sepsis. The generalizability of the neonatal SOFA (nSOFA) for neonatal late-onset infection-related mortality remains unknown.

OBJECTIVE

To determine the generalizability of the nSOFA for neonatal late-onset infection-related mortality across multiple sites.

DESIGN, SETTING, AND PARTICIPANTS

A multicenter retrospective cohort study was conducted at 7 academic neonatal intensive care units between January 1, 2010, and December 31, 2019. Participants included 653 preterm (<33 weeks) very low-birth-weight infants.

EXPOSURES

Late-onset (>72 hours of life) infection including bacteremia, fungemia, or surgical peritonitis.

MAIN OUTCOMES AND MEASURES

The primary outcome was late-onset infection episode mortality. The nSOFA scores from survivors and nonsurvivors with confirmed late-onset infection were compared at 9 time points (T) preceding and following event onset.

RESULTS

In the 653 infants who met inclusion criteria, median gestational age was 25.5 weeks (interquartile range, 24-27 weeks) and median birth weight was 780 g (interquartile range, 638-960 g). A total of 366 infants (56%) were male. Late-onset infection episode mortality occurred in 97 infants (15%). Area under the receiver operating characteristic curves for mortality in the total cohort ranged across study centers from 0.71 to 0.95 (T0 hours), 0.77 to 0.96 (T6 hours), and 0.78 to 0.96 (T12 hours), with utility noted at all centers and in aggregate. Using the maximum nSOFA score at T0 or T6, the area under the receiver operating characteristic curve for mortality was 0.88 (95% CI, 0.84-0.91). Analyses stratified by sex or Gram-stain identification of pathogen class or restricted to infants born at less than 25 weeks' completed gestation did not reduce the association of the nSOFA score with infection-related mortality.

CONCLUSIONS AND RELEVANCE

The nSOFA score was associated with late-onset infection mortality in preterm infants at the time of evaluation both in aggregate and in each center. These findings suggest that the nSOFA may serve as the foundation for a consensus definition of sepsis in this population.

Parenteral lipid emulsions induce unique ileal fatty acid and metabolomic profiles but do not increase the risk of necrotizing enterocolitis in preterm pigs

Necrotizing enterocolitis (NEC) is a manifestation of maladaptive intestinal responses in preterm infants centrally medicated by unattenuated inflammation. Early in the postnatal period, preterm infants develop a deficit in arachidonic and docosahexaenoic acid, both potent regulators of inflammation. We hypothesized that the fatty acid composition of parenteral lipid emulsions uniquely induces blood and intestinal fatty acid profiles which, in turn, modifies the risk of NEC development. Forty-two preterm pigs were randomized to receive one of three lipid emulsions containing 100% soybean oil (SO), 15% fish oil (MO15), or 100% fish oil (FO100) with enteral feedings over an 8-day protocol. Blood and distal ileum tissue were collected for fatty acid analysis. The distal ileum underwent histologic, proteomic, and metabolomic analyses. Eight pigs [3/14 SO (21%), 3/14 MO15 (21%), and 2/14 FO100 (14%)] developed NEC. No differences in NEC risk were evident between groups despite differences in induced fatty acid profiles in blood and ileal tissue. Metabolomic analysis of NEC versus no NEC tissue revealed differences in tryptophan metabolism and arachidonic acid-containing glycerophospholipids. Proteomic analysis demonstrated no differences by lipid group; however, 15 proteins differentiated NEC versus no NEC in the domains of tissue injury, glucose uptake, and chemokine signaling. Exposure to parenteral lipid emulsions induces unique intestinal fatty acid and metabolomic profiles; however, these profiles are not linked to a difference in NEC development. Metabolomic and proteomic analyses of NEC versus no NEC intestinal tissue provide mechanistic insights into the pathogenesis of NEC in preterm infants.NEW & NOTEWORTHY Exposure to parenteral lipid emulsions induces unique intestinal fatty acid and metabolomic profiles; however, these profiles are not linked to a difference in NEC risk in preterm pigs. Metabolomic and proteomic analyses provide mechanistic insights into NEC pathogenesis. Compared with healthy ileal tissue, metabolites in tryptophan metabolism and arachidonic acid-containing glycerophospholipids are increased in NEC tissue. Proteomic analysis differentiates NEC versus no NEC in the domains of tissue injury, glucose uptake, and chemokine signaling.

Exclusive Maternal Milk Compared With Exclusive Formula on Growth and Health Outcomes in Very-Low-Birthweight Preterm Infants: Phase II of the Pre-B Project and an Evidence Analysis Center Systematic Review

As part of the Pre-B Project, a systematic review was conducted to evaluate associations between exclusive maternal milk (≥75%) intake and exclusive formula intake and growth and health outcomes in very-low-birthweight (VLBW) preterm infants. The protocols from the Academy of Nutrition and Dietetics' Evidence Analysis Center and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist were followed. Thirteen observational studies were included; 11 studies reported data that could be synthesized in a pooled analysis. The evidence is very uncertain (very low quality) about the effect of exclusive maternal milk on all outcomes due to observational study designs and risk of selection, performance, detection, and reporting bias in most of the included studies. Very-low-quality evidence suggested that providing VLBW preterm infants with exclusive maternal milk was not associated with mortality, risk of necrotizing enterocolitis, sepsis, or developing bronchopulmonary dysplasia, as compared with exclusive preterm formula, but exclusive maternal milk was associated with a lower risk of retinopathy of prematurity (very low certainty). Results may change when additional studies are conducted. There was no difference in weight, length, and head circumference gain between infants fed fortified exclusive maternal milk and infants receiving exclusive preterm formula; however, weight and length gain were lower in infants fed non-fortified exclusive maternal milk. Given the observational nature of human milk research, cause-and-effect evidence was lacking for VLBW preterm infants.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=86829, PROSPERO ID: CRD42018086829.

Tokophobia and fear of birth: a workshop consensus statement on current issues and recommendations for future research

Objective: To discuss and develop a statement on the current state of the evidence and opinion in Fear of Childbirth (FoC) and Tokophobia (Tocophobia), and to provide recommendations. Background: A group met in 2019 to discuss the state of clinical and academic knowledge relating to FoC/Tokophobia. Five key areas were agreed as the focus of the meeting. Methods: 12 internationally acknowledged experts, in this or a closely related area (e.g. PTSD) met to discuss their understanding of the evidence for FoC/ Tokophobia and current practice. The consensus described in this paper constitutes the expression of the general opinion of the participants and does not necessarily imply unanimity. Keys points: Work focussed on tokophobia is recent and there remains a wide range of issues, which were addressed in the workshop including complexity in defining prevalence, a theoretical lack of understanding, which creates challenge for robust assessment and the identification of risk factors. An improved aetiological and developmental understanding of the tokophobia is required to underpin appropriate, effective and evidence-based interventions. Evaluation of pathways of care and relevant interventions, should be a focus of future research. Conclusion: Significant gaps remain within the FoC/tokophobia knowledge base. Further research is necessary.

Maltodextrin-induced intestinal injury in a neonatal mouse model

Prematurity and enteral feedings are major risk factors for intestinal injury leading to necrotizing enterocolitis (NEC). An immature digestive system can lead to maldigestion of macronutrients and increased vulnerability to intestinal injury. The aim of this study was to test in neonatal mice the effect of maltodextrin, a complex carbohydrate, on the risk of intestinal injury. The goal was to develop a robust and highly reproducible murine model of intestinal injury that allows insight into the pathogenesis and therapeutic interventions of nutrient-driven intestinal injury. Five- to 6-day-old C57BL/6 mice were assigned to the following groups: dam fed (D); D+hypoxia+Klebsiella pneumoniae; maltodextrin-dominant human infant formula (M) only; M+hypoxia; and M+hypoxia+K. pneumoniae. The mice in all M groups were gavage fed five times a day for 4 days. Mice were exposed to hypoxia twice a day for 10 min prior to the first and last feedings, and K. pneumoniae was added to feedings as per group assignment. Mice in all M groups demonstrated reduced body weight, increased small intestinal dilatation and increased intestinal injury scores. Maltodextrin-dominant infant formula with hypoxia led to intestinal injury in neonatal mice accompanied by loss of villi, increased MUC2 production, altered expression of tight junction proteins, enhanced intestinal permeability, increased cell death and higher levels of intestinal inflammatory mediators. This robust and highly reproducible model allows for further interrogation of the effects of nutrients on pathogenic factors leading to intestinal injury and NEC in preterm infants.This article has an associated First Person interview with the first author of the paper.

The impact of maternal obesity and breast milk inflammation on developmental programming of infant growth

Background:

Little is known about how maternal obesity impacts breast milk (BM) composition and how BM composition may impact growth. We sought to determine the role of maternal body mass index (BMI) on BM inflammatory and oxidative stress markers and to delineate the role of these BM markers on infant growth.

Methods:

This was a secondary analysis of 40 mother-infant dyads. We first assessed the association between maternal BMI and BM marker (omega-6:omega-3 polyunsaturated fatty acid ratio (n-6:n-3 PUFA), leptin, interleukin (IL)-8, IL-6, IL-1β and malondialdehyde (MDA)) concentration at one (V1) and four (V4) months postpartum. We then examined the association between BM markers on infant growth trajectory from birth to seven months.

Results:

Higher maternal BMI was associated with higher BM n-6:n-3 PUFA (V1 β=0.12, 95% CI 0.01, 0.2; V4 β=0.13, 95% CI 0.01, 0.3) and leptin (V1 β=107, 95% CI 29, 184; V4 β=254, 95% CI 105, 403) concentrations. Infants exposed to high BM n-6:n-3 PUFA had higher BMI z-scores over time (p=0.01). Higher BM leptin was associated with lower infant percent fat mass at V4 (β=−9, 95% CI −17, −0.6). Infants exposed to high BM IL-8, IL-6, or IL-1β had higher weight z-scores over time (IL-8 p<0.001; IL-6 p<0.001; IL-1β p=0.02). There was no association between BM MDA and maternal BMI or infant growth.

Conclusions:

Higher maternal BMI is associated with higher BM n-6:n-3 PUFA and leptin concentrations. In addition, higher BM n-6:n-3 PUFA and inflammatory cytokines were associated with accelerated weight gain in infancy.

Breast Milk Lipids and Fatty Acids in Regulating Neonatal Intestinal Development and Protecting against Intestinal Injury

Human breast milk is the optimal source of nutrition for infant growth and development. Breast milk fats and their downstream derivatives of fatty acids and fatty acid-derived terminal mediators not only provide an energy source but also are important regulators of development, immune function, and metabolism. The composition of the lipids and fatty acids determines the nutritional and physicochemical properties of human milk fat. Essential fatty acids, including long-chain polyunsaturated fatty acids (LCPUFAs) and specialized pro-resolving mediators, are critical for growth, organogenesis, and regulation of inflammation. Combined data including in vitro, in vivo, and human cohort studies support the beneficial effects of human breast milk in intestinal development and in reducing the risk of intestinal injury. Human milk has been shown to reduce the occurrence of necrotizing enterocolitis (NEC), a common gastrointestinal disease in preterm infants. Preterm infants fed human breast milk are less likely to develop NEC compared to preterm infants receiving infant formula. Intestinal development and its physiological functions are highly adaptive to changes in nutritional status influencing the susceptibility towards intestinal injury in response to pathological challenges. In this review, we focus on lipids and fatty acids present in breast milk and their impact on neonatal gut development and the risk of disease.

Should formula for infants provide arachidonic acid along with DHA? A position paper of the European Academy of Paediatrics and the Child Health Foundation

Recently adopted regulatory standards on infant and follow-on formula for the European Union stipulate that from February 2020 onwards, all such products marketed in the European Union must contain 20-50 mg omega-3 DHA (22:6n-3) per 100 kcal, which is equivalent to about 0.5-1% of fatty acids (FAs) and thus higher than typically found in human milk and current infant formula products, without the need to also include ω-6 arachidonic acid (AA; 20:4n-6). This novel concept of infant formula composition has given rise to concern and controversy because there is no accountable evidence on its suitability and safety in healthy infants. Therefore, international experts in the field of infant nutrition were invited to review the state of scientific research on DHA and AA, and to discuss the questions arising from the new European regulatory standards. Based on the available information, we recommend that infant and follow-on formula should provide both DHA and AA. The DHA should equal at least the mean content in human milk globally (0.3% of FAs) but preferably reach 0.5% of FAs. Although optimal AA intake amounts remain to be defined, we strongly recommend that AA should be provided along with DHA. At amounts of DHA in infant formula up to ∼0.64%, AA contents should at least equal the DHA contents. Further well-designed clinical studies should evaluate the optimal intakes of DHA and AA in infants at different ages based on relevant outcomes.

Developmental Accretion of Docosahexaenoic Acid Is Independent of Fatty Acid Transporter Expression in Brain and Lung Tissues of C57BL/6 and Fat1 Mice

BACKGROUND

Developmental expression of fatty acid transporters and their role in polyunsaturated fatty acid concentrations in the postnatal period have not been evaluated.

OBJECTIVE

We hypothesized that transporter expression is developmentally regulated, tissue-specific, and that expression can modulate fatty acid accretion independently of diet.

METHODS

Brain and lung transporter expression were quantified in C57BL/6 wild-type (WT) and Fat1 mice. Pups were dam-fed until day 21. Dams were fed AIN-76A 10% corn oil to represent a typical North American/European diet. After weaning, mice were fed the same diet as dams. Gene expression of Fatp1, Fatp4, Fabp5, and Fat/cd36 was quantified by quantitative reverse transcriptase-polymerase chain reaction. Fatty acid concentrations were measured by GC-MS.

RESULTS

Brain docosahexaenoic acid (DHA) concentrations increased from day 3 to day 28 in both genotypes, with higher concentrations at days 3 and 14 in Fat1 than in WT mice [median (IQR)]: 10.7 (10.6-11.2) mol% compared with 6.6 (6.4-7.2) mol% and 12.5 (12.4-12.9) mol% compared with 8.9 (8.7-9.1) mol%, respectively; P < 0.05). During DHA accrual, transporter expression decreased. Fold changes in brain Fatp4, Fabp5, and Fat/cd36 were inversely correlated with fold changes in brain DHA concentrations in Fat1 relative to WT mice (ρ = -0.85, -0.75, and -0.78, respectively; P ≤ 0.001). Lung DHA concentrations were unchanged across the 3 time points for both genotypes. Despite unchanging DHA concentrations, there was increased expression of Fatp1 at days 14 and 28 (5-fold), Fatp4 at day 14 (2.3-fold), and Fabp5 at day 14 (3.8-fold) relative to day 3 in Fat1 mice. In WT mice, Fatp1 increased almost 5-fold at day 28 relative to day 3. There was no correlation between lung transporters and DHA concentrations in Fat1 relative to WT mice.

CONCLUSIONS

Development of fatty acid transporter expression in C57BL/6 WT and Fat1 mice is genotype and tissue specific. Further, postnatal accretion of brain DHA appears independent of transporter status, with tissue concentrations representing dietary contributions.

Early Enteral Administration of a Complex Lipid Emulsion Supplement Prevents Postnatal Deficits in Docosahexaenoic and Arachidonic Acids and Increases Tissue Accretion of Lipophilic Nutrients in Preterm Piglets

BACKGROUND

Preterm delivery and current nutrition strategies result in deficiencies of critical long-chain fatty acids (FAs) and lipophilic nutrients, increasing the risk of preterm morbidities. We sought to determine the efficacy of preventing postnatal deficits in FAs and lipophilic nutrients using an enteral concentrated lipid supplement in preterm piglets.

METHODS

Preterm piglets were fed a baseline diet devoid of arachidonic acid (AA) and docosahexaenoic acid (DHA) and randomized to enteral supplementation as follows: (1) Intralipid (IL), (2) complex lipid supplement 1 (CLS1) with an AA:DHA ratio of 0.25, or (3) CLS2 with an AA:DHA ratio of 1.2. On day 8, plasma and tissue levels of FAs and lipophilic nutrients were measured and ileum histology performed.

RESULTS

Plasma DHA levels decreased in the IL group by day 2. In contrast, DHA increased by day 2 compared with birth levels in both CLS1 and CLS2 groups. The IL and CLS1 groups demonstrated a continued decline in AA levels during the 8-day protocol, whereas AA levels in the CLS2 group on day 8 were comparable to birth levels. Preserving AA levels in the CLS2 group was associated with greater ileal villus height and muscular layer thickness. Lipophilic nutrients were effectively absorbed in plasma and tissues.

CONCLUSIONS

Enteral administration of CLS1 and CLS2 demonstrated similar increases in DHA levels compared with birth levels. Only CLS2 maintained AA birth levels. Providing a concentrated complex lipid emulsion with an AA:DHA ratio > 1 is important in preventing postnatal AA deficits.

Effect of polyunsaturated fatty acids on postnatal ileum development using the fat-1 transgenic mouse model

BACKGROUND

Long-chain polyunsaturated fatty acids (LCPUFAs) play a critical role in neonatal health. We hypothesized that LCPUFAs play an essential role in priming postnatal gut development. We studied the effect of LCPUFAs on postnatal gut development using fat-1 transgenic mice, which are capable of converting n-6 to n-3 LCPUFAs, and wild-type (WT) C57BL/6 mice.

METHODS

Distal ileum sections were collected from fat-1 and WT mice on days 3, 14, and 28. Fatty acid analyses, histology, RT-qPCR and intestinal permeability were performed.

RESULTS

Fat-1 mice, relative to WT mice, showed increased n-3 LCPUFAs levels (α-linolenic acid, docosahexaenoic acid, and eicosapentaenoic acid, p < 0.05) and decreased arachidonic acid levels (p < 0.05) in the ileum. Preweaning fat-1 mice, compared to WT, showed >50% reduced muc2, Tff3, TLR9, and Camp expression (p < 0.05), markers of the innate immune response. There was a >two-fold increased expression of Fzd5 and EphB2, markers of cell differentiation (p < 0.05), and Fabp2 and 6, regulators of fatty acid transport and metabolism (p < 0.05). Despite reduced expression of tight junction genes, intestinal permeability in fat-1 was comparable to WT mice.

CONCLUSIONS

Our data support the hypothesis that fatty acid profiles early in development modulate intestinal gene expression in formative domains, such as cell differentiation, tight junctions, other innate host defenses, and lipid metabolism.