Long chain fatty acids and related pro-inflammatory, specialized pro-resolving lipid mediators and their intermediates in preterm human milk during the first month of lactation

Specialized pro-resolving mediators in vascular inflammation and atherosclerotic cardiovascular disease

Timely resolution of the acute inflammatory response (or inflammation resolution) is an active, highly coordinated process that is essential to optimal health. Inflammation resolution is regulated by specific endogenous signalling molecules that function as 'stop signals' to terminate the inflammatory response when it is no longer needed; to actively promote healing, regeneration and tissue repair; and to limit pain. Specialized pro-resolving mediators are a superfamily of signalling molecules that initiate anti-inflammatory and pro-resolving actions. Without an effective and timely resolution response, inflammation can become chronic, a pathological state that is associated with many widely occurring human diseases, including atherosclerotic cardiovascular disease. Uncovering the mechanisms of inflammation resolution failure in cardiovascular diseases and identifying useful biomarkers for non-resolving inflammation are unmet needs. In this Review, we discuss the accumulating evidence that supports the role of non-resolving inflammation in atherosclerosis and the use of specialized pro-resolving mediators as therapeutic tools for the treatment of atherosclerotic cardiovascular disease. We highlight open questions about therapeutic strategies and mechanisms of disease to provide a framework for future studies on the prevention and treatment of atherosclerosis.

Associations of maternal inflammatory states with human milk composition in mothers of preterm infants

Introduction

Overweight/obesity (ow/ob) is increasing in prevalence in pregnant women, and it is associated with other pro-inflammatory states, such as pre-eclampsia, gestational diabetes, and preterm labor. Data are lacking if mothers experiencing inflammatory states who deliver preterm have mother's own milk (MOM) with differing inflammatory markers or pro-inflammatory fatty acid (FA) profiles.

Methods

The aim was to explore associations of maternal pre- and perinatal inflammatory states with levels of inflammatory markers and/or FAs in longitudinal samples of MOM from mothers of preterm infants born <1,250 g. Inflammatory states included pre-pregnancy ow/ob, diabetes, chorioamnionitis (chorio), preterm labor (PTL), premature rupture of membranes (PROM), pre-eclampsia, and cesarian delivery. In MOM, inflammatory markers studied included c-reactive protein (CRP), free choline, IFN-Ɣ, IL-10, IL-1β, IL-1ra, IL-6, IL-8, and TNF-α, and FAs included omega-6:omega-3 ratio, arachidonic acid, docosahexaenoic acid, linoleic acid, monounsaturated FAs, and saturated FAs. The above inflammatory states were assessed individually, and the healthiest mothers (normal BMI, no chorio, and ± no pre-eclampsia) were grouped. Regression analysis tested associations at baseline (day 5) and over time using generalized estimating equations.

Results

A total of 92 infants were included who were delivered to mothers (42% ow/ob) at a median gestational age of 27.7 weeks and birth weight of 850 g. MOM CRP was 116% higher (relative change 2.16) in mothers with ow/ob at baseline than others (p = 0.01), and lower (relative change 0.46, 0.33, respectively) in mothers in the two "healthy groups" at baseline (both p < 0.05) than others. MOM IL-8 levels were lower with chorio and PTL at baseline. No significant associations were found for other individual or grouped inflammatory states nor for other MOM inflammatory markers nor FA profiles at baseline.

Discussion

In conclusion, MOM CRP levels are positively associated with inflammatory states, such as ow/ob. Reassuringly, there was no association between FA profiles or most other inflammatory markers and maternal inflammatory states. Further studies are needed to determine potential associations or ramifications of MOM CRP in vulnerable preterm infants.

Identification of omega-3 oxylipins in human milk-derived extracellular vesicles with pro-resolutive actions in gastrointestinal inflammation

Introduction

Premature infants (PIs) are at risk of suffering necrotizing enterocolitis (NEC), and infants consuming human milk (HM) show a lower incidence than infants receiving formula. The composition of HM has been studied in depth, but the lipid content of HM-derived small extracellular vesicles (HM sEVs) remains unexplored. Identifying these molecules and their biological effects has potential for the treatment of intestinal disorders in PIs and could contribute to the development of HM-based fortified formulas.

Methods

We isolated HM sEVs from HM samples and analyzed their oxylipin content using liquid chromatography coupled to mass spectrometry, which revealed the presence of anti-inflammatory oxylipins. We then examined the efficacy of a mixture of these oxylipins in combating inflammation and fibrosis, in vitro and in a murine model of inflammatory bowel disease (IBD).

Results

HM-related sEVs contained higher concentrations of oxylipins derived from docosahexaenoic acid, an omega-3 fatty acid. Three anti-inflammatory oxylipins, 14-HDHA, 17-HDHA, and 19,20-DiHDPA (ω3 OXLP), demonstrated similar efficacy to HM sEVs in preventing cell injury, inducing re-epithelialization, mitigating fibrosis, and modulating immune responses. Both ω3 OXLP and HM sEVs effectively reduced inflammation in IBD-model mice, preventing colon shortening, infiltration of inflammatory cells and tissue fibrosis.

Discussion

Incorporating this unique cocktail of oxylipins into fortified milk formulas might reduce the risk of NEC in PIs and also provide immunological and neurodevelopmental support.

Determination of oxylipins and their precursors in breast milk by solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry

Oxylipins and their precursors (long-chain polyunsaturated fatty acids, LCPUFAs) are key intercellular signaling molecules influencing the inflammatory response. Each oxylipin has pro- and/or anti-inflammatory effects, and the relative abundance of different oxylipins can alter the inflammatory balance, making it important to clarify the oxylipin profile of breast milk for optimal infant health. The extraction, identification, and simultaneous quantification of oxylipins in breast milk are challenging due to the structural similarity, limited stability, and the low endogenous concentration of oxylipins and the complex matrix of breast milk. This study aimed to develop a solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry (SPE-UPLC-MS/MS) method for the comprehensive and specific quantification of oxylipins and their precursors in breast milk. The LC conditions (including column, mobile phase, and gradient conditions) and SPE procedure (including SPE cartridges, elution solvent, and elution volume) were optimized to achieve accurate quantification and better analyte recovery. A single 18-minute chromatographic run allows for the quantification of 20 oxylipins and 5 PUFAs. The results showed good linearity (R2 > 0.99) over the concentration range of 2 to 100 ng/mL, with the instrument detection limits ranging from 0.01 to 0.90 ng/mL for oxylipins and 0.02 to 0.59 ng/mL for PUFAs. The method is rapid, sensitive, and reproducible (RSD ≤ 10%) and is suitable for the quantitative analysis of oxylipins and their precursors in infant formula samples.

Docosahexaenoic acid-rich algae oil supplementation in mothers of preterm infants is associated with a modification in breast milk oxylipins profile

Oxylipins are derived from enzymatic and non-enzymatic oxidation of n-3 and n-6 long-chain polyunsaturated fatty acids. They are known to be involved in inflammatory processes. The aim of this study was to describe the breast milk oxylipin profile following a docosahexaenoic acid (DHA) supplementation of mothers of preterm infants. We examined the oxylipins profile in breast milk collected at day 14 post-delivery, of 40 mothers who delivered before 29 weeks of gestation and who were supplemented with either DHA-rich algae oil (S-DHA) or a placebo (PL). These mothers were selected from the MOBYDIck cohort (NCT02371460 registered on 25/05/2015 in ClinicalTrials.gov) according to the supplementation received (S-DHA vs. PL) and the DHA content quartiles as measured in breast milk (Low vs. High) to generate four study groups. Milk oxylipins, as ng/mL of milk, were analyzed by LC-MS/MS. Ten oxylipins derived from DHA were higher in the S-DHA-High group than the other three groups (P < 0.001). The 18-HEPE, was also higher in the S-DHA-High group (0.11 ± 0.01) compared to the other groups (P = 0.0001). Compared to the PL-Low group, there was a reduction in pro-inflammatory prostaglandins found in the S-DHA-High group with lower levels of prostaglandins PGF_2α (0.21 ± 0.45 in the S-DHA-High group vs. 1.87 ± 0.44 in the PL-Low group, P = 0.03) and of PGE₂ (0.33 ± 0.26 in the S-DHA-High group vs. 1.28 ± 0.25 in the PL-Low group, P = 0.04).In sum, the DHA supplementation was linked with a predominance of anti-inflammatory oxylipins in breast milk of mothers who delivered very preterm, like 17(S)-HDHA and 18-HEPE, precursors of D and E resolvins respectively. This was also accompanied with a lower level of pro-inflammatory prostaglandins.

Oxylipins as Potential Regulators of Inflammatory Conditions of Human Lactation

Chronic low-grade inflammation can be associated with obesity or subclinical mastitis (SCM), which is associated with poor infant growth in low- to middle-income country settings. It is unknown what physiological mechanisms are involved in low milk supply, but our research group has shown that mothers with low milk supply have higher inflammatory markers. Studies investigating oxylipin signaling have the potential to help explain mechanisms that mediate the impacts of inflammation on milk production. Animal studies have reported various elevated oxylipins during postpartum inflammation, mastitis, and mammary involution in ruminant models. Several investigations have quantified oxylipins in human milk, but very few studies have reported circulating oxylipin concentrations during lactation. In addition, there are technical considerations that must be addressed when reporting oxylipin concentrations in human milk. First, the majority of milk oxylipins are esterified in the triglyceride pool, which is not routinely measured. Second, total milk fat should be considered as a covariate when using milk oxylipins to predict outcomes. Finally, storage and handling conditions of milk samples must be carefully controlled to ensure accurate milk oxylipin quantitation, which may be affected by highly active lipases in human milk.

Early Growth and Cognitive Development in Children Born Preterm: Relevance of Maternal Body Mass Index

OBJECTIVE

Maternal prepregnancy body mass index (BMI) represents a surrogate marker of fetal exposures to the maternal metabolism during pregnancy. Yet, it remains poorly understood whether this marker indicates risk of altered trajectories in postnatal growth and development in children born preterm. This study aimed to determine whether maternal prepregnancy BMI is associated with altered growth and development in children born preterm.

STUDY DESIGN

A retrospective cohort study evaluated prepregnancy BMI as the exposure for childhood outcomes using linear regression and mixed effects models. The 38 children included in this follow-up evaluation originally participated in a prospective, observational cohort study to determine longitudinal levels of lipid species in preterm human milk expressed by women who delivered prior to 32 weeks. Childhood outcomes in this study were anthropometric measures during hospitalization (n = 38), after discharge through 36 months (n = 34) and Bayley-III developmental scores through 18 months corrected age (n = 26).

RESULTS

In 38 children born prior to 32 weeks, higher maternal prepregnancy BMI was independently associated with higher preterm infant growth velocity during hospitalization, but not associated with in-hospital change in length or head circumference and/or postdischarge growth. In univariate linear regression models, higher maternal BMI was associated with lower cognitive scores at 18 months corrected age. This significant association remained in an adjusted model accounting for relevant influences on early childhood development.

CONCLUSION

Increasing maternal prepregnancy BMI may reflect risk of altered growth and cognitive development in children born preterm.

KEY POINTS

· Maternal BMI was associated with early preterm infant weight gain.. · Maternal BMI was not associated with postdischarge growth.. · Increased maternal BMI may be associated with lower cognitive function scores in offspring..

In vitro Digestion Characteristics of Hydrolyzed Infant Formula and Its Effects on the Growth and Development in Mice

Infant formula, an important food for babies, is convenient and nutritious, and hydrolyzed formulas have attracted much attention due to their non-allergicity. However, it is uncertain whether hydrolyzed formulars cause obesity and other side effects in infants. Herein, three infant formulas, standard (sIF), partially hydrolyzed (pHIF), and extensively hydrolyzed (eHIF), were analyzed in an in vitro gastrointestinal digestion model. With increasing degree of hydrolysis, the protein moleculars, and allergenicity of the proteins decreased and the long-chain polyunsaturated fatty acid content increased. Moreover, the digestion model solutions quickly digested the small fat globules and proteins in the hydrolyzed formula, allowing it to become electrostatically stable sooner. The eHIF-fed mice presented larger body sizes, and exhibited excellent exploratory and spatial memory abilities in the maze test. Based on villus height and crypt depth histological characterizations and amplicon sequencing, eHIF promoted mouse small intestine development and changed the gut microbiota composition, eventually favoring weight gain. The mouse spleen index showed that long-term infant formula consumption might be detrimental to immune system development, and the weight-bearing swimming test showed that eHIF could cause severe physical strength decline. Therefore, long-term consumption of infant formula, especially eHIF, may have both positive and negative effects on mouse growth and development, and our results might shed light on feeding formula to infants.

Lipids and Long Chain Polyunsaturated Fatty Acids in Preterm Infants

Fatty acids are critical bioactives for fetal and neonatal development. Premature delivery and current nutritional strategies pose several challenges in restoring fatty acid balance in the preterm infant. The impact on fatty acid balance and outcomes using lipid emulsions, enteral nutrition, and enteral supplements are reviewed, including a summary of the most recent large clinical trials of enteral fatty acid supplementation for the preterm infant. Research gaps remain in successfully implementing nutritional strategies to optimize fatty acid status in preterm infants.

Fish oil rich in eicosapentaenoic acid and docosahexaenoic acid in sow diets modifies oxylipins and immune indicators in colostrum and milk

Colostrum and milk are the first nutrient sources for newborn piglets. In addition, n-3 fatty acids (FAs) and their oxygenated derivatives (oxylipins) have the capacity to modulate immune components. The aim of the current study was to include a fish oil rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in sow diets to promote an increase of anti-inflammatory molecules in colostrum and milk to benefit piglets. Thirty-six sows were randomly assigned from insemination to the end of lactation to either a control diet with animal fat (15 g/kg in gestation and 30 g/kg in lactation) or an n-3 diet in which animal fat was totally (gestation) or half (lactation) replaced by an equivalent amount of solid fish oil. Performance of sows and piglets was monitored during the study. Colostrum and milk samples were obtained after the birth of the first piglet and at weaning, respectively. From all samples (n = 18 per treatment), FAs were quantified by gas chromatography and immunoglobulins and cytokines by ELISA. Three samples per treatment were randomly selected to analyse oxylipin composition by liquid chromatography-tandem mass spectrometry. In colostrum and in milk, the n-3 FA (P = 0.020 and P < 0.001), particularly EPA (P < 0.001 and P < 0.001) and DHA (P < 0.001 and P < 0.001), and also their oxygenated derivatives were increased in samples from sows fed n-3 diet. Fish oil had no effect on immunoglobulin concentrations, but reduced tumour necrosis factor α (TNFα) (P = 0.011) and a tendency to reduce interleukin 10 (IL10) (P = 0.059) were observed in milk. In conclusion, fish oil in sow diets increased n-3 FA, particularly EPA and DHA, and their oxygenated derivatives in colostrum and milk, reducing TNFα and IL10 in milk.

Specialized Pro-Resolving Lipid Mediators in Neonatal Cardiovascular Physiology and Diseases

Cardiovascular disease remains a leading cause of mortality worldwide. Unresolved inflammation plays a critical role in cardiovascular diseases development. Specialized Pro-Resolving Mediators (SPMs), derived from long chain polyunsaturated fatty acids (LCPUFAs), enhances the host defense, by resolving the inflammation and tissue repair. In addition, SPMs also have anti-inflammatory properties. These physiological effects depend on the availability of LCPUFAs precursors and cellular metabolic balance. Most of the studies have focused on the impact of SPMs in adult cardiovascular health and diseases. In this review, we discuss LCPUFAs metabolism, SPMs, and their potential effect on cardiovascular health and diseases primarily focusing in neonates. A better understanding of the role of these SPMs in cardiovascular health and diseases in neonates could lead to the development of novel therapeutic approaches in cardiovascular dysfunction.

Method optimization of oxylipin hydrolysis in nonprocessed bovine milk indicates that the majority of oxylipins are esterified

The oxidation of polyunsaturated fatty acids produces bioactive primary oxidation products known as oxylipins. In many biological matrices, the majority of oxylipins are bound (i.e. esterified), and a relatively small proportion (<10%) exists in the free form. The present study tested whether this extends to bovine milk following method evaluation of various extraction and base hydrolysis protocols for measuring bound oxylipins. Free (unbound) oxylipins were also measured. Folch extraction followed by sodium carbonate hydrolysis in the presence of methanol containing 0.1% of acetic acid and 0.1% of butylated hydroxytoluene resulted in greater oxylipin concentrations and better surrogate standard recoveries compared to other methods that did not involve Folch extraction or the addition of methanol with hydrolysis base. Sodium hydroxide was better than sodium carbonate in hydrolyzing bound oxylipins under the same conditions. Milk analysis of oxylipins with mass-spectrometry following Folch extraction and sodium hydroxide hydrolysis revealed that 95% of oxylipins in bovine milk were esterified. Most of the detected oxylipins were derived from linoleic acid, which accounted for 92 and 88% of oxylipins in the free and esterified pools, respectively. These results demonstrate that the majority of bovine milk oxylipins are bound, and that linoleic-acid derived metabolites are the most abundant oxylipin species in free and bound lipid pools. Additional studies are needed to understand the role of different oxylipin pools in both calf and human nutrition. PRACTICAL APPLICATION: A method involving Folch lipid extraction and sodium hydroxide hydrolysis was validated for esterified oxylipin measurements in bovine milk. Application of the method revealed that the majority (∼95%) of oxylipins in bovine milk were bound. Linoleic-acid derived oxylipins were the most abundant species in both bound and free milk fractions (88-92%). The results highlight the presence of a new pool of oxidized lipids in milk, potentially involved in modifying its sensory and nutritional properties.

Perinatal Dietary Polyunsaturated Fatty Acids in Brain Development, Role in Neurodevelopmental Disorders

n-3 and n-6 polyunsaturated fatty acids (PUFAs) are essential fatty acids that are provided by dietary intake. Growing evidence suggests that n-3 and n-6 PUFAs are paramount for brain functions. They constitute crucial elements of cellular membranes, especially in the brain. They are the precursors of several metabolites with different effects on inflammation and neuron outgrowth. Overall, long-chain PUFAs accumulate in the offspring brain during the embryonic and post-natal periods. In this review, we discuss how they accumulate in the developing brain, considering the maternal dietary supply, the polymorphisms of genes involved in their metabolism, and the differences linked to gender. We also report the mechanisms linking their bioavailability in the developing brain, their transfer from the mother to the embryo through the placenta, and their role in brain development. In addition, data on the potential role of altered bioavailability of long-chain n-3 PUFAs in the etiologies of neurodevelopmental diseases, such as autism, attention deficit and hyperactivity disorder, and schizophrenia, are reviewed.

Distinct maternal amino acids and oxylipins predict infant fat mass and fat-free mass indices

Interested in maternal determinants of infant fat mass index (FMI) and fat-free mass index (FFMI), considered as predictors for later development of obesity, we analysed amino acids (AA) and oxylipins in maternal serum and breast milk (BM). FMI and FFMI were calculated in 47 term infants aged 4 months (T4). Serum AA were analysed in pregnancy (T1, T2) and 6-8 weeks postpartum (T3). At T3, AA and oxylipins were analysed in BM. Biomarker-index-associations were identified by regression analysis. Infant FMI (4.1 ± 1.31 kg/m²; MW ± SD) was predicted by T2 proline (R² adj.: 7.6%, p = .036) and T3 BM 11-hydroxy-eicosatetraenoic-acid (11-HETE) and 13-hydroxy-docosahexaenoic-acid (13-HDHA; together:35.5% R² adj., p < .001). Maternal peripartum antibiotics (AB) emerged as confounders (+AB: 23.5% higher FMI; p = .025). Infant FFMI (12.1 ± 1.19 kg/m²; MW ± SD) was predicted by histidine (R² adj.: 14.5%, p < .001) and 17-HDHA (BM, R² adj.:19.3%, p < .001), determined at T3. Confirmed in a larger cohort, the parameters could elucidate connections between maternal metabolic status, nutrition, and infant body development.

Preterm human milk at lactation weeks 1 and 4 categorized by maternal pre-pregnancy body mass index: Metabolomics and lipidomics datasets

Human milk samples were prospectively obtained from women who delivered prior to the 32nd week of gestation [1]. The 36 preterm human milk samples analysed in this dataset were collected at week 1 and week 4 of lactation. Samples were categorized as being from women with normal pre-pregnancy body mass index (BMI 18–24.9 kg/m²) versus overweight/obese (BMI ≥25). Whole milk samples were frozen at −80 Celsius without prior processing and shipped for analysis on dry ice. Untargeted metabolomic and lipidomic platforms using UPLC-MS/MS and infusion-MS analysis for select lipids were performed by Metabolon. Lipidomic analysis included detection of complex lipids found in the milk fat globule membrane. Data were categorized by maternal BMI, week of lactation as well as gestational age at delivery. Data sheets are separated based on whether they report metabolomics versus lipidomics, as well as whether they report output from samples collected at week 1 versus week 4 of lactation. These data allow calculating relationships between clinical variables and human milk components. As an illustrative example, correlations between pre-pregnancy BMI and total milk fatty acids were calculated for this report using the Spearman correlation. These data will inform scientists of variability in milk composition attributable to maternal pre-pregnancy BMI as well as changes in milk composition as milk matures during lactation from week 1 to week 4. These data may best be used for generating hypotheses and justification of future work investigating whether maternal pre-pregnancy body mass index impacts preterm human milk composition.

Maternal ω3 docosapentaenoic acid inhibits infant allergic dermatitis through TRAIL-expressing plasmacytoid dendritic cells in mice

Background

Maternal dietary exposures are considered to influence the development of infant allergies through changes in the composition of breast milk. Cohort studies have shown that ω3 polyunsaturated fatty acids (PUFAs) in breast milk may have a beneficial effect on the preventing of allergies in infants; however, the underlying mechanisms remain to be investigated. We investigated how the maternal intake of dietary ω3 PUFAs affects fatty acid profiles in the breast milk and their pups and reduced the incidence of allergic diseases in the pups.

Methods

Contact hypersensitivity (CHS) induced by 2,4‐dinitrofluorobenzene (DNFB) and fluorescein isothiocyanate was applied to the skin in pups reared by mother maintained with diets mainly containing ω3 or ω6 PUFAs. Skin inflammation, immune cell populations, and expression levels of immunomodulatory molecules in pups and/or human cell line were investigated by using flow cytometric, immunohistologic, and quantitative RT‐PCR analyses. ω3 PUFA metabolites in breast milk and infant's serum were evaluated by lipidomics analysis using LC‐MS/MS.

Results

We show that maternal intake of linseed oil, containing abundant ω3 α‐linolenic acid, resulted in the increased levels of ω3 docosapentaenoic acid (DPA) and its 14‐lipoxygenation products in the breast milk of mouse dams; these metabolites increased the expression of TNF‐related apoptosis‐inducing ligand (TRAIL) on plasmacytoid dendritic cells (pDCs) in their pups and thus inhibited infant CHS. Indeed, the administration of DPA‐derived 14‐lipoxygenation products to mouse pups ameliorated their DNFB CHS.

Conclusion

These findings suggest that an inhibitory mechanism in infant skin allergy is induced through maternal metabolism of dietary ω3 PUFAs in mice.

Distribution of Free and Esterified Oxylipins in Cream, Cell, and Skim Fractions of Human Milk

Human milk contains oxylipins involved in infant development. Although oxylipins have been identified in whole or skim milk, their localization within human milk cream, cell, and skim fractions is not known. This study determined the distribution of free and esterified oxylipins in cream, cell, and skim fractions of human milk. Out of 72 oxylipins probed by mass-spectrometry, 42, 29, and 41 oxylipins (free or bound) were detected in cream, cell, and skim fractions, respectively. Over 90% of free and bound oxylipins were derived from linoleic acid in all milk fractions. Other oxylipins were derived from n-6 arachidonic acid and dihomo-gamma-linolenic acid, and n-3 alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. Free oxylipins were more abundant in skim milk (59.9% of total oxylipins) compared to cream and cell pellet, whereas esterified oxylipins were most abundant in milk cream and cell pellets (74.9-76.9%). The heterogenous distribution of oxylipins in different fractions of human milk may regulate the guided release of these bioactive signaling molecules within infants.

Arachidonic Acid in Human Milk

Breastfeeding is universally recommended as the optimal choice of infant feeding and consequently human milk has been extensively investigated to unravel its unique nutrient profile. The human milk lipid composition is unique and supplies specifically long-chain polyunsaturated fatty acids (LC-PUFAs), in particular, arachidonic acid (ARA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3). Arachidonic acid (ARA) is the most predominant long-chain polyunsaturated fatty acid in human milk, albeit at low concentrations as compared to other fatty acids. It occurs predominantly in the triglyceride form and to a lesser extent as milk fat globule membrane phospholipids. Human milk ARA levels are modulated by dietary intake as demonstrated by animal and human studies and consequently vary dependent on dietary habits among mothers and regions across the globe. ARA serves as a precursor to eicosanoids and endocannabinoids that also occur in human milk. A review of scientific and clinical studies reveals that ARA plays an important role in physiological development and its related functions during early life nutrition. Therefore, ARA is an important nutrient during infancy and childhood and, as such, appropriate attention is required regarding its nutritional status and presence in the infant diet. Data are emerging indicating considerable genetic variation in encoding for desaturases and other essential fatty acid metabolic enzymes that may influence the ARA level as well as other LC-PUFAs. Human milk from well-nourished mothers has adequate levels of both ARA and DHA to support nutritional and developmental needs of infants. In case breastfeeding is not possible and infant formula is being fed, experts recommend that both ARA and DHA are added at levels present in human milk.

Plasma Oxidative Status in Preterm Infants Receiving LCPUFA Supplementation: A Pilot Study

After birth, preterm infants are deficient in arachidonic acid (ARA), docosahexaenoic acid (DHA), and antioxidants, increasing their risk of oxidative stress-related pathologies. The principal aim was to evaluate if supplementation with long-chain polyunsaturated fatty acids (LCPUFAs) improves antioxidant defenses. In total, 21 preterm infants were supplemented with ARA and DHA in a 2:1 ratio (ARA:DHA-S) or with medium-chain triglycerides (MCT-S). Plasma n-3 and n-6 LCPUFAs were measured at birth, postnatal day 28, and 36 weeks of postmenstrual age (36 WPA) by gas chromatography–mass spectroscopy. Plasma antioxidants (glutathione (GSH), catalase, and thiols) and oxidative damage biomarkers (malondialdehyde (MDA), carbonyls) were analyzed at the same time points by spectrophotometry, and scores of antioxidant status (Antiox-S) and oxidative damage (Proxy-S) were calculated. At 36 WPA, linoleic acid (LA) and dihomo-γ-linolenic acid (DGLA) were decreased in ARA:DHA-S compared to the MCT-S group (LA: ARA:DHA-S = 18.54 ± 1.68, MCT-S = 22.80 ± 1.41; p = 0.018; DGLA: ARA:DHA-S = 1.68 ± 0.38, MCT-S = 2.32 ± 0.58; p = 0.018). Furthermore, α-linolenic acid (ALA) was increased in ARA:DHA-S (ARA:DHA-S = 0.52 ± 0.33, MCT-S = 0.22 ± 0.10; p = 0.018). Additionally, LA:DHA ratio was decreased in the ARA:DHA-S compared to control group (ARA:DHA-S = 6.26 ± 2.35, MCT-S = 8.21 ± 2.65; p = 0.045). By the end of supplementation (36 WPA), catalase, thiol groups, and Antiox-S were significantly higher in neonates receiving ARA:DHA-S compared to those receiving MCT-S, with no differences in oxidative stress biomarkers. In conclusion, ARA:DHA supplementation in preterm neonates resulted in an overall improvement in antioxidant to oxidant balance and a decrease in early fatty acid precursors of the n-6 relative to the n-3 pathway. These effects may reduce oxidative stress and inflammation.

Biosynthetic metabolomes of cysteinyl-containing immunoresolvents

Resolution of inflammation is an active process regulated by specialized proresolving mediators where we identified 3 new pathways producing allylic epoxide-derived mediators that stimulate regeneration [i.e., peptido-conjugates in tissue regeneration (CTRs)]. Here, using self-limited Escherichia coli peritonitis in mice, we identified endogenous maresin (MaR) CTR (MCTR), protectin (PD) CTR (PCTR), and resolvin CTR in infectious peritoneal exudates and distal spleens, as well as investigated enzymes involved in their biosynthesis. PCTRs were identified to be temporally regulated in peritoneal exudates and spleens. PCTR1 and MCTR1 were each produced by human recombinant leukotriene (LT) C₄ synthase (LTC₄S) and glutathione S-transferases (GSTs) [microsomal GST (mGST)2, mGST3, and GST-μ (GSTM)4] from their epoxide precursors [16S,17S-epoxy-PD (ePD) and 13S,14S-epoxy-MaR (eMaR)], with preference for GSTM4. Both eMaR and ePD inhibited LTB₄ production by LTA₄ hydrolase. LTC₄S, mGST2, mGST3, and GSTM4 were each expressed in human M1- and M2-like macrophages where LTC₄S inhibition increased CTRs. Finally, PCTR1 showed potent analgesic action. These results demonstrate CTR biosynthesis in mouse peritonitis, human spleens, and human macrophages, as well as identification of key enzymes in these pathways. Moreover, targeting LTC₄S increases CTR metabolomes, giving a new strategy to stimulate resolution and tissue regeneration.-Jouvene, C. C., Shay, A. E., Soens, M. A., Norris, P. C., Haeggström, J. Z., Serhan, C. N. Biosynthetic metabolomes of cysteinyl-containing immunoresolvents.

Considerations for Preterm Human Milk Feedings When Caring for Mothers Who Are Overweight or Obese

BACKGROUND

Mother's milk is the recommended source of nutrition for all newborns. Preterm infants may be further compromised by maternal factors that impede successful lactation and alter milk composition.

PURPOSE

To review and summarize the state of the science regarding implications of maternal overweight and obesity on successful lactation and associated alterations in preterm mother's milk composition.

METHODS/SEARCH STRATEGY

PubMed, EMBASE, and Web of Science searches were performed using relevant key words to identify references addressing maternal overweight or obesity, prematurity, human milk, and lactation.

FINDINGS/RESULTS

In the United States, more than half of women enter pregnancy with an overweight or obese body mass index. These women have increased risk of adverse pregnancy outcomes and obstetric complications that can undermine successful initiation and continuation of lactation, including preterm birth. Maternal overweight and obesity are also associated with alterations in mother's milk composition.

IMPLICATIONS FOR PRACTICE

Mother-preterm infant dyads affected by maternal overweight and obesity are at risk for barriers to initiation and continuation of lactation. Support for early initiation of milk expression is needed. Continued support, especially during the first weeks of lactation, can facilitate sustained milk production.

IMPLICATIONS FOR RESEARCH

Considerable knowledge gaps remain in this area of human milk science. Future research is needed to facilitate more comprehensive understanding of differences in milk composition associated with maternal overweight and obesity and their impact on clinical outcomes in the preterm infant.

Oxylipins and Free Fatty Acids in Parenteral Lipid Emulsions Currently Used in Preterm Infant Care: An In Vitro Study

Lipid emulsions used to support nutrition in preterm infants contain long-chain polyunsaturated fatty acids (LCPUFAs) as a source of essential fatty acids; these LCPUFAs and their parent polyunsaturated fatty acid (PUFA) can be oxidized by a variety of mechanisms to bioactive molecules called oxylipins, which are signaling molecules that initiate and/or resolve inflammation. The aim of this study was to explore levels of free LCPUFA and their related oxylipins in 3 commercially available lipid emulsions (Intralipid, SMOFlipid, and ClinOleic) using ultra high-performance liquid chromatography mass spectroscopy. Free LCPUFA were detected in all lipid emulsions tested. Seven, 8, and 9 different oxylipin compounds were detected in the 3 emulsions, respectively. The oxylipins detected were mainly derived from omega-6 PUFAs; these included 13-hydroxyoctadecadienoic acid from linoleic acid and 5-hydroxyeicosatetraenoic acid derived from arachidonic acid. It may be clinically important to know that oxylipins exist in lipid emulsions and to evaluate their potential effects on preterm infants.

Oxylipin concentration, but not fatty acid composition, is altered in human donor milk pasteurised using both thermal and non-thermal techniques

Human donor milk (DM) is Holder pasteurised (62·5°C, 30 min) to ensure its microbiological safety for infant consumption. In low-resource settings, flash heating is used to pasteurise milk. Although there is considerable interest in non-thermal alternatives (high hydrostatic pressure processing (HHP) and UVC irradiation) for pasteurisation, their effect on the fatty acid composition is not well understood. Of particular interest is the effect of pasteurisation on the generation of oxylipins. DM from eight mothers containing bacteria >5 × 107 colony-forming units/l was used. In a paired design, each pool of milk underwent four pasteurisation techniques: Holder; flash heating; UVC (250 nm, 25 min) and HHP (500 MPa, 8 min). Fatty acids were quantified by GC-flame ionisation detection and oxylipins derived from arachidonic acid; 18-carbon PUFA (α-linolenic acid, linoleic acid and γ-linolenic acid) and EPA/DHA were measured by liquid chromatography-tandem MS in aliquots of raw and processed milk. There were no significant changes to the composition of fatty acids following all pasteurisation techniques compared with raw milk. The n-6:n-3 ratio remained constant ranging from 6·4 to 6·6. Several arachidonic acid-derived oxylipins were highest post-UVC and elevated post-HHP compared with raw milk. Several oxylipins derived from 18-carbon PUFA (linoleic and α-linolenic acids) were elevated in UVC-treated milk. EPA/DHA-derived oxylipins were on average, unaffected by pasteurisation. Although some PUFA-derived oxylipins were increased following UVC and HHP, no method affected the fatty acid composition of human DM. Further research is needed to determine if varying levels of oxylipins in human DM as a result of processing can potentially mediate cellular signalling; proliferation and apoptosis, especially important for preterm infant development.

Modern Methods of Sample Preparation for the Analysis of Oxylipins in Biological Samples

Oxylipins are potent lipid mediators derived from polyunsaturated fatty acids, which play important roles in various biological processes. Being important regulators and/or markers of a wide range of normal and pathological processes, oxylipins are becoming a popular subject of research; however, the low stability and often very low concentration of oxylipins in samples are a significant challenge for authors and continuous improvement is required in both the extraction and analysis techniques. In recent years, the study of oxylipins has been directly related to the development of new technological platforms based on mass spectrometry (LC–MS/MS and gas chromatography–mass spectrometry (GC–MS)/MS), as well as the improvement in methods for the extraction of oxylipins from biological samples. In this review, we systematize and compare information on sample preparation procedures, including solid-phase extraction, liquid–liquid extraction from different biological tissues.

Identification of specialized pro-resolving mediator clusters from healthy adults after intravenous low-dose endotoxin and omega-3 supplementation: a methodological validation

Specialized pro-resolving mediator(s) (SPMs) are produced from the endogenous ω-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and accelerate resolution of acute inflammation. We identified specific clusters of SPM in human plasma and serum using LC-MS/MS based lipid mediator (LM) metabololipidomics in two separate laboratories for inter-laboratory validation. The human plasma cluster consisted of resolvin (Rv)E1, RvD1, lipoxin (LX)B₄, 18-HEPE, and 17-HDHA, and the human serum cluster consisted of RvE1, RvD1, AT-LXA₄, 18-HEPE, and 17-HDHA. Human plasma and serum SPM clusters were increased after ω-3 supplementation (triglyceride dietary supplements or prescription ethyl esters) and low dose intravenous lipopolysaccharide (LPS) challenge. These results were corroborated by parallel determinations with the same coded samples in a second, separate laboratory using essentially identical metabololipidomic operational parameters. In these healthy subjects, two ω-3 supplementation protocols (Study A and Study B) temporally increased the SPM cluster throughout the endotoxin-challenge time course. Study A and Study B were randomized and Study B also had a crossover design with placebo and endotoxin challenge. Endotoxin challenge temporally regulated lipid mediator production in human serum, where pro-inflammatory eicosanoid (prostaglandins and thromboxane) concentrations peaked by 8 hours post-endotoxin and SPMs such as resolvins and lipoxins initially decreased by 2 h and were then elevated at 24 hours. In healthy adults given ω-3 supplementation, the plasma concentration of the SPM cluster (RvE1, RvD1, LXB₄, 18-HEPE, and 17-HDHA) peaked at two hours post endotoxin challenge. These results from two separate laboratories with the same samples provide evidence for temporal production of specific pro-resolving mediators with ω-3 supplementation that together support the role of SPM in vivo in inflammation-resolution in humans.

Breast Milk Lipidome Is Associated with Early Growth Trajectory in Preterm Infants

Human milk is recommended for feeding preterm infants. The current pilot study aims to determine whether breast-milk lipidome had any impact on the early growth-pattern of preterm infants fed their own mother's milk. A prospective-monocentric-observational birth-cohort was established, enrolling 138 preterm infants, who received their own mother's breast-milk throughout hospital stay. All infants were ranked according to the change in weight Z-score between birth and hospital discharge. Then, we selected infants who experienced "slower" (n = 15, -1.54 ± 0.42 Z-score) or "faster" (n = 11, -0.48 ± 0.19 Z-score) growth; as expected, although groups did not differ regarding gestational age, birth weight Z-score was lower in the "faster-growth" group (0.56 ± 0.72 vs. -1.59 ± 0.96). Liquid chromatography-mass spectrometry lipidomic signatures combined with multivariate analyses made it possible to identify breast-milk lipid species that allowed clear-cut discrimination between groups. Validation of the selected biomarkers was performed using multidimensional statistical, false-discovery-rate and ROC (Receiver Operating Characteristic) tools. Breast-milk associated with faster growth contained more medium-chain saturated fatty acid and sphingomyelin, dihomo-γ-linolenic acid (DGLA)-containing phosphethanolamine, and less oleic acid-containing triglyceride and DGLA-oxylipin. The ability of such biomarkers to predict early-growth was validated in presence of confounding clinical factors but remains to be ascertained in larger cohort studies.

The role of specialized pro-resolving mediators in maternal-fetal health

Infants developing in a pro-inflammatory intrauterine environment have a significant risk for severe complications after birth. It has been shown that omega-3 fatty acids reduce inflammation, and also reduce early preterm births and decrease risk of infant admission to the neonatal intensive care unit. However, the mechanism for omega-3 fatty acids exerting these effects was previously unknown. Recent evidence has shown that downstream products of polyunsaturated fatty acids called specialized pro-resolving mediators may mediate inflammatory physiology, thus playing an important role in maternal-fetal health. In this review, current knowledge relating to specialized pro-resolving mediators in pregnancy, delivery, and perinatal disease states will be summarized.