Early postnatal changes of lipoprotein subclass profile in late preterm infants

HDL Function across the Lifespan: From Childhood, to Pregnancy, to Old Age

The function of high-density lipoprotein (HDL) particles has emerged as a promising therapeutic target and the measurement of HDL function is a promising diagnostic across several disease states. The vast majority of research on HDL functional biology has focused on adult participants with underlying chronic diseases, whereas limited research has investigated the role of HDL in childhood, pregnancy, and old age. Yet, it is apparent that functional HDL is essential at all life stages for maintaining health. In this review, we discuss current data regarding the role of HDL during childhood, pregnancy and in the elderly, how disturbances in HDL may lead to adverse health outcomes, and knowledge gaps in the role of HDL across these life stages.

Characterization of lipoproteins and associated lipidome in very preterm infants: a pilot study

BACKGROUND

Preterm birth is associated with higher risks of suboptimal neurodevelopment and cardiometabolic disease later in life. Altered maternal-fetal lipid supply could play a role in such risks. Our hypothesis was that very preterm infants born with very low birth weight (VLBW) have altered lipidome and apolipoprotein profiles, compared with term infants.

METHODS

Seven mothers of VLBW infants born at <32 GA and 8 full-term mother-infant dyads were included. Cholesterol and triglycerides in lipoproteins were determined in maternal plasma and in the two blood vessels of the umbilical cord (vein (UV) and artery (UA)) following FPLC isolation. Apolipoprotein concentrations in lipoproteins and plasma lipidomic analysis were performed by LC-MS/MS.

RESULTS

We found higher cholesterol and VLDL-cholesterol in UV and UA and lower apolipoprotein A-I in HDL2 in UV in preterm neonates. Phosphatidylcholine (PC) containing saturated and monounsaturated fatty acids and specific sphingomyelin species were increased in UV and UA, whereas PC containing docosahexaenoic acid (DHA) was reduced in UV of VLBW neonates.

CONCLUSIONS

Lower DHA-PC suggests a lower DHA bioavailability and may contribute to the impaired neurodevelopment. Altered HDL-2, VLDL, and sphingomyelin profile reflect an atherogenic risk and increased metabolic risk at adulthood in infants born prematurely.

IMPACT

Lower ApoA-I in HDL2, and increased specific sphingomyelin and phosphatidylcholine containing saturated and monounsaturated fatty acid could explain the accumulation of cholesterol in umbilical vein in VLBW preterm neonates. Decreased phosphatidylcholine containing DHA suggest a reduced DHA availability for brain development in VLBW preterm infants. Characterization of alterations in fetal lipid plasma and lipoprotein profiles may help to explain at least in part the causes of the elevated cardiovascular risk known in people born prematurely and may suggest that a targeted nutritional strategy based on the composition of fatty acids carried by phosphatidylcholine may be promising in infants born very early.

Maternal cholesterol levels during gestation: boon or bane for the offspring?

An increase in cholesterol levels is perceived during pregnancy and is considered as a normal adaptive response to the development of the fetus. In some pregnancies, excessive increase in total cholesterol with high levels of Low-Density Lipoprotein leads to maladaptation by the fetus to cholesterol demands, resulting in a pathological condition termed as maternal hypercholesterolemia (MH). MH is considered clinically irrelevant and therefore cholesterol levels are not routinely checked during pregnancy, as a consequence of which there is scarce information on its global prevalence in pregnant women. Studies have reported that MH during pregnancy can cause atherogenesis in adults emphasizing the concept of in utero programming of fetus. Moreover, Gestational Diabetes Mellitus, obesity and Polycystic Ovary Syndrome are potential risk factors which strengthen combined pathologies in placenta and fetuses of mothers with MH. However, lack of conclusive evidence on cholesterol transport and underlying programming demand substantial research to develop population-based life style strategies for women in their childbearing years. The current review focuses on the mechanisms and outcomes of MH from existing epidemiological as well as experimental data and presents a detailed insight on this novel risk factor of cardiovascular diseases.

Are maternal metabolic syndrome and lipid profile associated with preterm delivery and preterm premature rupture of membranes?

AIM

We aimed to evaluate the association of metabolic syndrome (MetS), its components and lipid profile in mid-pregnancy with preterm delivery and preterm premature rupture of membranes (PPROM).

METHODS

This prospective cohort study was conducted on 203 pregnant women between 24 and 28 weeks of gestation, undergoing gestational diabetes screening test with 50 g glucose challenge test (GCT). Fasting serum total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG) levels were measured during the week after GCT assessment. Information on the participants' pre-pregnancy weight, demographic/reproductive characteristics, and height and blood pressure (BP) measurements were documented at baseline entry into the study. Metabolic syndrome was defined as the co-existence of 3 or more of the following criteria: Body mass index (BMI) before pregnancy ≥ 30 kg/m², BP ≥ 130/85 mmHg, GCT ≥ 140 mg/dl, TG ≥ 150 mg/dl, and HDL-C ≤ 50 mg/dl. All participants were followed through routine prenatal care, up to delivery. Any deliveries or rupture of membranes of less than 37 weeks of pregnancy were considered preterm delivery and PPROM, respectively. Statistical analysis was performed by SPSS V.20, and p value of less than 0.05 was considered significant.

FINDINGS

MetS was detected in 10 (4.9%) of participants. Logistic regression analysis showed HDL-C levels, and hypertension were associated with spontaneous preterm delivery [(OR 0.952, 95% CI 0.910-0.995), (OR 1.629, 95% CI 1.554-1.709) respectively], but no statistically significant results were found for PPROM.

CONCLUSIONS

Low HDL-C levels and hypertension in mid-pregnancy are associated with the occurrence of spontaneous preterm deliveries, indicating that MetS and its components should be monitored more closely in pregnancy.

Feeding the Late and Moderately Preterm Infant: A Position Paper of the European Society for Paediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition

Nutritional guidelines and requirements for late or moderately preterm (LMPT) infants are notably absent, although they represent the largest population of preterm infants. The European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Committee on Nutrition (CoN) performed a review of the literature with the aim to provide guidance on how to feed infants born LMPT, and identify gaps in the literature and research priorities.Only limited data from controlled trials are available. Late preterm infants have unique, often unrecognized, vulnerabilities that predispose them to high rates of nutritionally related morbidity and hospital readmissions. They frequently have feeding difficulties that delay hospital discharge, and poorer rates of breastfeeding initiation and duration compared with term infants. This review also identified that moderately preterm infants frequently exhibit postnatal growth restriction.The ESPGHAN CoN strongly endorses breast milk as the preferred method of feeding LMPT infants and also emphasizes that mothers of LMPT infants should receive qualified, extended lactation support, and frequent follow-up. Individualized feeding plans should be promoted. Hospital discharge should be delayed until LMPT infants have a safe discharge plan that takes into account local situation and resources.In the LMPT population, the need for active nutritional support increases with lower gestational ages. There may be a role for enhanced nutritional support including the use of human milk fortifier, enriched formula, parenteral nutrition, and/or additional supplements, depending on factors, such as gestational age, birth weight, and significant comorbidities. Further research is needed to assess the benefits (improved nutrient intakes) versus risks (interruption of breast-feeding) of providing nutrient-enrichment to the LMPT infant.

Influence of i.v. lipid emulsion on lipoprotein subclass in preterm infants

BACKGROUND

Lipid emulsions given i.v. are normally rapidly metabolized by apoprotein recruited from high-density lipoprotein (HDL) particles in the blood. Very low-birthweight infants (VLBWI), however, have a low rate of lipid clearance from the blood, and therefore lipid emulsions must be given carefully to minimize the risk of hyperlipidemia. The purpose of this study was to evaluate the influence of i.v. lipid emulsion on lipoprotein subclass profile in VLBWI during the early postnatal period.

METHODS

Forty-six VLBWI who had been given different doses of lipid emulsion in the first few days after birth were enrolled in the present study. Triglyceride and cholesterol content of each lipoprotein subclass was measured at 3 weeks after birth, and their correlation with the total dose of lipid emulsion was calculated.

RESULTS

There was no correlation between the total dose of lipid emulsion and the triglyceride and cholesterol content in any subclasses of very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL). There was a significant negative correlation between the total dose of lipid emulsion and the triglyceride content in very large (P < 0.05, r = -0.32), large (P < 0.01, r = -0.47) and medium HDL (P < 0.05, r = -0.34) particles; and the cholesterol content in large (P < 0.01, r = -0.47) and medium HDL (P < 0.01, r = -0.4) particles.

CONCLUSION

Lipid emulsion influenced the triglyceride and cholesterol content of HDL particles in VLBWI, suggesting that lipid emulsion can affect lipid metabolism in this infant population in the early postnatal period.

DNA methylations of MC4R and HNF4α are associated with increased triglyceride levels in cord blood of preterm infants

The association of preterm birth with obesity and metabolic syndrome later in life is well established. Although the biological mechanism for this association is poorly understood, epigenetic alterations of metabolic-related genes in early life may have important roles in metabolic dysfunction. Thus, we investigated the associations of DNA methylations of melanocortin 4 receptor (MC4R) and hepatocyte nuclear factor 4 alpha (HNF4α) with metabolic profiles in cord blood of term and preterm infants.We measured metabolic profiles in cord blood samples of 85 term and 85 preterm infants. DNA methylation and mRNA expression levels of MC4R and HNF4α in cord blood cells were quantified using pyrosequencing and real-time PCR. Triglyceride (TG) levels were grouped by percentile as low (<10th percentile), mid (11th-89th percentiles), and high (>90th percentile). A multiple linear regression model was used to assess the differential effects of DNA methylation on metabolic indices in cord blood between term and preterm infants.The beta-coefficients for associations between TG levels and methylation statuses of MC4R-CpG3 and HNF4α-CpG2 in the P1 promoter differed significantly between term and preterm infants (P = 0.04 and P = 0.003, respectively). DNA methylation statuses of MC4R-CpG3 and HNF4α-CpG2 in the P1 promoter were significantly lower in preterm infants in the high-TG group compared with those in the mid- and low-TG groups (P = 0.01). Notably, preterm infants in the high-TG group had higher TG levels in cord blood than term infants in the high-TG group (60.49 vs 54.57 mg/dL). In addition, MC4R and HNF4α expression levels were higher in preterm infants than in term infants (P < 0.05).Epigenetic alterations of the newly identified genes MC4R and HNF4α in early life might contribute to metabolic profile changes, especially increased TG levels, in the cord blood of preterm infants.

Enhanced delivery of lipophilic nutrients to the infant brain via high density lipoprotein

Lipoproteins are the primary carriers of lipophilic cognitive nutrients such as docosahexaenoic acid, lutein, and α-tocopherol within circulation. The critical roles these nutrients play in growth and development are well established, and as such, their efficient delivery to the infant brain is crucial. Given the selectivity of the blood brain barrier, the lipoprotein fraction primarily responsible for brain delivery of these nutrients must be determined so that efforts aimed at increasing brain nutrient uptake, via lipoprotein profile manipulation, can be appropriately focused. Based on the preclinical and clinical data reviewed here, we hypothesize that high density lipoprotein is the fraction chiefly responsible for delivery of docosahexaenoic acid, lutein, and α-tocopherol to the infant brain. As high density lipoprotein levels tend to be lower in preterm, formula-fed infants as compared to their full-term, breast-fed counterparts, efforts aimed at increasing circulating high density lipoprotein levels, and subsequent delivery of cognitive lipophilic nutrients to the brain via manipulation of formula composition, may be most effective if targeted to this group. These efforts include (1) limiting the polyunsaturated: saturated fatty acid ratio; (2) increasing the casein: whey ratio; (3) altering the proportion of saturated fatty acids found in the sn-2 position of the parent triglyceride; (4) cholesterol supplementation; and (5) nucleotide supplementation.

Insulin-like growth factor-1 and lipoprotein profile in cord blood of preterm small for gestational age infants

Low birth weight was associated with cardiometabolic diseases in adult age. Insulin-like growth factor-1 (IGF-1) has a crucial role in fetal growth and also associates with cardiometabolic risks in adults. Therefore, we elucidated the association between IGF-1 level and serum lipids in cord blood of preterm infants. The subjects were 41 consecutive, healthy preterm neonates (27 male, 14 female) born at <37-week gestational age, including 10 small for gestational age (SGA) infants (<10th percentile). IGF-1 levels and serum lipids were measured in cord blood, and high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC) and very low-density lipoprotein triglyceride (VLDLTG) levels were determined by HPLC method. SGA infants had lower IGF-1 (13.1 ± 5.3 ng/ml), total cholesterol (TC) (55.0 ± 14.8), LDLC (21.6 ± 8.3) and HDLC (26.3 ± 11.3) levels, and higher VLDLTG levels (19.0 ± 12.7 mg/dl) than in appropriate for gestational age (AGA) infants (53.6 ± 25.6, 83.4 ± 18.9, 36.6 ± 11.1, 38.5 ± 11.6, 8.1 ± 7.0, respectively). In simple regression analyses, log IGF-1 correlated positively with birth weight (r = 0.721, P < 0.001), TC (r = 0.636, P < 0.001), LDLC (r = 0.453, P = 0.006), and HDLC levels (r = 0.648, P < 0.001), and negatively with log TG (r = -0.484, P = 0.002) and log VLDL-TG (r = -0.393, P = 0.018). Multiple regression analyses demonstrated that IGF-1 was an independent predictor of TC, HDLC and TG levels after the gestational age and birth weight were taken into account. In preterm SGA infants, cord blood lipids profile altered with the concomitant decrease in IGF-1 level.

Paraoxonase 1 lactonase activity and distribution in the HDL subclasses in the cord blood

OBJECTIVES

Paraoxonase 1 (PON1) is a lactonase with important antioxidant and immunoprotective properties. We hypothesized that PON1 lactonase activity, PON1, and high-density lipoprotein (HDL) subclasses distribution are different in neonates than in adults.

MATERIAL AND METHODS

We studied 83 healthy term neonates (34 males and 49 females) who were born by spontaneous, uncomplicated vaginal delivery. The study also included 17 paired maternal blood samples as well as 20 non-pregnant women collected for comparison. Total and free PON1 lactonase and arylesterase activity, HDL subclasses, PON1, and apolipoprotein distribution in the subclasses were assayed.

RESULTS

PON1 arylesterase activity in the cord blood represented 37% ± 4 of the maternal activity, whereas the PON1 lactonase activity amounted to only 23% ± 5 of the maternal activity. The free arylesterase and lactonase activities were higher in the cord blood by 16 and 36%, respectively. There is a 65% lower HDL2b PON1 in the cord blood than in the maternal serum. When the Lipoprint HDL subclasses were assayed, the neonates showed a larger content (52% higher) of very large HDL as well as a characteristic peak in the middle-sized HDL5 which is unremarkable in the mothers.

CONCLUSION

The novel findings of this study are that the neonates have lower PON1 lactonase activity, higher free PON1, different distributions of PON1 in the HDL subclasses as compared with their mother and adults as well as a distinctive HDL subclass lipid profile. Our data also suggest that the neonate HDL is enriched with an intermediate-sized (and/or less charged HDL) that is also rich in active PON1.

Small-dense low-density lipoproteins are the predominant apoB-100-containing lipoproteins in cord blood

OBJECTIVES

Low density lipoprotein (LDL)-cholesterol level in cord blood is approximately 30%. The aim of our study was to specifically explore LDL apoB distribution across sizes in cord blood serum.

DESIGN AND METHODS

We studied 83 healthy neonates and 17 paired healthy mothers. Plasma glucose and serum lipids, such as low-density lipoprotein (LDL) cholesterol (LDL-C), HDL cholesterol (HDL-C) and triglycerides (TG), were measured using enzymatic methods. Distribution of apoB-100 was performed by western blot and immunodetection on native 4-12% polyacrylamide gels. LDL subclasses were analyzed by Lipoprint-LDL.

RESULTS

Neonates show the expected lower content of apoB LDL and small dense LDL is the predominant apoB containing particle: 67 ± 7%. However, only 1.5% is sdLDL by Lipoprint. Maternal serum contains a large proportion of apoB in smaller LDL, 47 ± 6% as compared to non-pregnant women, 6 ± 1%, p<0.001.

CONCLUSIONS

Neonates show the expected lower content of apoB-LDL but in an inverse distribution; sdLDL being the predominant particle. This novel finding for apoB sdLDL is consistent with previous data on HPLC studies showing increased middle and small-sized LDL lipid content in neonates as compared to adults which amounts to 84% of total LDL. Comparison of the results with Lipoprint LDL (lipids) with gradient gel electrophoresis native western blot (apoB-100) suggests that neonates carry fractions of small LDL that are comparatively poor in lipids as compared with their mothers. Further studies are warranted on the issue of sdLDL in neonates.