A Review of the Relationship Between the Appetite-Regulating Hormone Leptin Present in Human Milk and Infant Growth

Breastfeeding duration and nutritional status of infants and toddlers in Spain. LAyDI study (PAPenRed)

INTRODUCTION

Breastfeeding appears to protect the onset of obesity in infants. The aim is to know whether breastfeeding duration is associated with the risk of obesity in infants and toddlers aged 12 and 24 months.

MATERIAL AND METHODS

Prospective longitudinal study in a cohort of children born in Spain between April 2017 and March 2018 (LAyDI study) in the paediatric primary care system conducted in the framework of the PAPenRed research network. Analysis of breastfeeding duration (group 1: fewer than 6 months; group: more than 6 months) and its association with anthropometric variables.

RESULTS

A total of 1495 patients attended the 12 months preventive child health visit and 1073 patients the 24 months visit. We found a statistically significant association between breastfeeding duration and weight-for-age, BMI-for-age and weight-for-length/height at 12 and 24 months; breastfeeding duration of less than 6 months was significantly associated with overweight and obesity (based on BMI-for-age and weight-for-length/height) at ages 12 and 24 months. Maternal pre-pregnancy BMI acted as a modifier on the association between breastfeeding duration and overweight and obesity (based on BMI-for-age).

CONCLUSIONS

A breastfeeding duration of less than 6 months is associated with a higher percentage of overweight and obesity at ages 12 and 24 months, although maternal pre-pregnancy BMI modifies this relationship at 24 months.

Breast milk leptin concentrations and infant anthropometric indicators in SGA versus non-SGA breastfed infants born at term

Leptin concentrations in breast milk can influence metabolic programming during the first months of life. Small for gestational age (SGA) newborns show a peculiar growth pattern after birth, which can lead to adulthood diseases. This study aims to assess an association between leptin concentration in mature breast milk and the infant anthropometric indicators of the SGA and the non-SGA groups, in addition, to comparing the hormone level between these groups. A longitudinal study was performed with mother-infant pairs. The maternal sociodemographic information was collected in the first 48 h postpartum. Breast milk was collected at one month postpartum and leptin concentrations were obtained by immunoassays. The infant anthropometric measurements were collected at three and six months postpartum and included weight, height (to body mass index-BMI calculated), triceps skinfold (TSF), and subscapular skinfold (SSF). The BMI for age (BMI/A), TSF, and SSF were calculated by Z-score indicators. Data from 67 mother-infant pairs (n = 16 SGA and n = 51 non-SGA) were analyzed. In univariate analyses, the breast milk of the SGA group had lower leptin concentrations than the non-SGA group (p = 0.006), however, after adjustment, there was no difference between groups (p = 0.181). In the SGA group, there was a significant association between leptin concentrations and lower SSF at six months in infants, after adjustment (p = 0.003). In the non-SGA group, the breast milk leptin was associated with lower BMI/A at three and six months in infants, after adjustment (p = 0.002 and p = 0.010, respectively). The association between breast milk leptin concentrations with SSF in the SGA group and BMI/A in the non-SGA group suggests that leptin may be a modulating factor in infant growth in the first months of life.

Leptin, Adiponectin, and Melatonin Modulate Colostrum Lymphocytes in Mothers with Obesity

Pregnancy complicated by obesity is associated with adverse triggered gestational and neonatal outcomes, with reductions in the subtypes of CD4+ T-lymphocytes representing the modulators of inflammation. It needs to be better established how maternal nutritional statuses impact the neuroendocrine-immune system's action and affect the immunological mechanisms of the maternal-infant relationship via breastfeeding. This study examined the effects of maternal obesity on human colostrum lymphocytes and the intracellular mechanisms of lymphocyte modulation in the presence of leptin, adiponectin, and melatonin via cell proliferation; the release of intracellular calcium; and apoptosis induction. This cross-sectional study analyzed colostrum samples from 52 puerperal splits and divided them into overweight and eutrophic groups. Colostrum lymphocytes underwent immunophenotyping and cell proliferation by flow cytometry and intracellular calcium release and apoptosis assays by immunofluorescence in the presence or absence of hormones. Significant differences were considered when p < 0.05 by the chi-square or t-test. Maternal obesity reduced the population of T-lymphocytes and TCD4+ in human colostrum and proliferative activities (p < 0.05). These hormones restore lymphocyte proliferation to a level similar to the eutrophic group (p < 0.05). Leptin, adiponectin, melatonin hormones, and biological actions consolidated in the scientific literature also represent maternal and infant protection mechanisms via colostrum and the modulation of human colostrum lymphocytes.

Associations between maternal adiposity and appetite-regulating hormones in human milk are mediated through maternal circulating concentrations and might affect infant outcomes

Background

Appetite-regulating hormones (ARH) in human milk (HM) are suggested to affect infants’ milk intake and possibly infant growth. Maternal adiposity might contribute to higher levels of ARH in HM, either from the mammary gland or from raised circulating levels due to higher adiposity. Counterfactual-based mediation analysis can define indirect and direct effects between HM ARH and maternal and infant factors, and might be an important tool when investigating the mother-milk-infant triad.

Objective

We aim to investigate whether potential associations between (1) maternal adiposity and HM ARH and (2) HM ARH and infant milk intake and growth are mediated through maternal and infant plasma ARH, respectively.

Materials and methods

Maternal and infant anthropometry and body composition, HM and blood samples were collected from 223 mother-infant dyads participating in the Mother, Infant and Lactation Quality study at three postpartum visits from 1 to 8.49 months. Leptin, insulin and adiponectin were analyzed using immunoassays. Mediation analyses using linear mixed-effect models were applied to investigate the direct and indirect effects through maternal and infant plasma hormone concentrations.

Results

A positive association between maternal body-mass-index (BMI) and HM leptin was mediated by maternal plasma leptin by 29% when fixing BMI to < 25 kg/m², and through 51% when fixing BMI to ≥ 25 kg/m² (p_interaction < 0.01). There was no mediated effect through plasma insulin in the association between BMI and HM insulin (p = 0.068). We found negative and positive associations between HM insulin and total milk intake and infant weight, respectively, however, these diminished in mediation analyses with reduced sample sizes.

Conclusion

Our main results suggest that the association between maternal adiposity and HM leptin was mediated through circulating leptin to a stronger degree for mothers with overweight compared to mothers with normal-weight. This indicates that excess maternal adiposity, and the resulting rise of circulating leptin and possible concomitant low-grade inflammation, may be reflected in HM composition.

Clinical trials registry number

NCT03254329.