Giovanna Marchini

Human milk oligosaccharide (HMO) composition varies among lactating mothers and changes during the course of lactation period. Interindividual variation is largely driven by fucosyltransferase (FUT2 and FUT3) polymorphisms resulting in 4 distinct milk groups. Little is known regarding whether maternal physiological status contributes to HMO variability. We characterized the trajectories of 20 major HMOs and explored whether maternal pre-pregnancy body mass index (ppBMI), mode of delivery, or parity may affect milk HMO composition. Using longitudinal breastmilk samples from healthy mothers (n = 290) across 7 European countries, we characterized HMO composion and employed mixed linear models to explore associations of maternal characteristics with individual HMOs. We observed HMO-specific temporal trajectories and milk group dependencies. We observed relatively small but significant differences in HMO concentrations based on maternal ppBMI, mode of delivery and parity. Our findings suggest that HMO composition to be regulated time-dependently by an enzyme as well as substrate availability and that ppBMI, mode of delivery, and parity may influence maternal physiology to affect glycosylation marginally within the initital period of lactation. Our observational study is the largest European standardized and longitudinal (up to 4 months) milk collection study assessing HMO concentrations and basic maternal characteristics. Time of lactation and milk groups had the biggest impact on HMO variation. Future studies need to elucidate these observations and assess the physiological significance for the breastfed infant.

BACKGROUND: Peptide antibiotics are part of the surface defences against microbial intruders. However, the presence and significance of these innate immune effectors in the skin barrier of the newborn infant have not yet been appreciated. Erythema toxicum neonatorum is an inflammatory skin reaction of unknown aetiology and significance, commonly present in the healthy newborn infant. OBJECTIVES: As peptide antibiotics are upregulated in inflammatory skin disorders, we hypothesized that this also could be the case in erythema toxicum. We also investigated if the vernix caseosa, a cream-like white substance present on the skin of the infant at birth, might contribute to host defences. METHODS: The presence of the human antibacterial peptide LL-37 was investigated by immunohistochemistry and confocal imaging of skin biopsies from four 1-day-old infants with an erythema toxicum rash and four matched newborns without the rash. In addition, we analysed the expression of LL-37 and human beta defensin-1, an antibacterial peptide of epithelial origin, by reverse transcriptase-polymerase chain reaction. Finally, we screened for antibacterial components in vernix material obtained from six healthy newborns by inhibition zone assays. RESULTS: All biopsies from the lesions of erythema toxicum showed a dense, nodular infiltrate with numerous LL-37-expressing cells located in the dermal layer and a clear localization of the peptide within CD15-expressing neutrophils, EG2-expressing eosinophils and CD1a-expressing dendritic cells. LL-37 was also found to be located in CD1a-expressing Langerhans cells and a positive staining for the peptide was seen throughout the whole epidermal layer, both in infants with and without the rash. Skin samples from infants with the rash of erythema toxicum showed a constitutive expression of human beta defensin-1, while the expression of LL-37 seemed to be induced. Furthermore, LL-37 and lysozyme were detected in the protein fractions derived from the vernix caseosa, and these fractions exhibited a clear antibacterial activity. CONCLUSIONS: Peptide antibiotics are present in the vernix caseosa and in the skin of the healthy newborn infant, indicating effective innate immune protection already during fetal and neonatal life.

It is well established that sensory stimulation is of great importance for the growth of and for the physiological and psychological development of infants. Supplementary sensory stimulation such as non-nutritive sucking and tactile stimulation has been shown to increase the growth rate and the maturation of premature infants. In human neonates non-nutritive sucking has a vagally mediated influence on the levels of some gastrointestinal hormones. In animal experiments afferent electrical stimulations of the sciatic nerves at low intensity leads to an activation of the vagal nerves and to a consequent release of vagally controlled gastrointestinal hormones such as gastrin and cholecystokinin. We therefore assume that both non-nutritive sucking and tactile stimulation trigger the activity of sensory nerves which leads to a release of vagally regulated gut hormones. Since gut hormones stimulate gastrointestinal motor and secretory activity and the growth of the gastrointestinal tract, and enhance the glucose-induced insulin release, they may contribute to the beneficial effects on maturation and growth caused by sensory stimulation. In the breast-feeding situation, the sucking of the child elicits similar reflexes in the mother leading to an activation of the maternal gut endocrine system and a consequent increase in energy uptake. These data indicate that many types of neurogenic reflexes induced in mother-infant interactions are of importance for the energy economy of both mother and child.

AIMS: The aim of this work was to investigate the possible effect of human cathelicidin antimicrobial peptide LL37 on biofilm formation of Staphylococcus epidermidis, a major causative agent of indwelling device-related infections. METHODS AND RESULTS: We performed initial attachment assay and biofilm formation solid surface assay in microtitre plates, as well as growth experiment in liquid medium using laboratory strain Staph. epidermidis ATCC35984. We found that already a low concentration of the peptide LL37 (1 mg l(-1)) significantly decreased both the attachment of bacteria to the surface and also the biofilm mass. No growth inhibition was observed even at 16 mg l(-1) concentration of LL37, indicating a direct effect of the peptide on biofilm production. CONCLUSIONS: As biofilm protects bacteria during infections in humans and allows their survival in a hostile environment, inhibition of biofilm formation by LL37 may have a key role to prevent bacterial colonization on indwelling devices. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings suggest that this host defence factor can be a potential candidate in prevention and treatment strategies of Staph. epidermidis infections in humans.