Characterization of polypeptides of vernix caseosa [VC] and Its role on the neonate skin surfsce as an innate antimicrobial barrier

ABSTRACT

Vernix caseosa [VC] is a greasy substance, that gradually covers the fetal skin during the last trimester of pregnancy. The vernix had been shown to have antimicrobial properties. Given the strategic position of vernix [a relatively unstudied material] on the fetal skin surface, this study aimed to investigate whether natural antimicrobial peptides/proteins contribute to surface protection of newborns at birth, hence the significant basis for leaving vernix in place at birth was provided. This study characterized peptides and proteins in vernix with emphasis on antimicrobial activity. Concentrated peptide/protein extracts were obtained from samples of vernix from full-term healthy newborn infants and screened for antimicrobial activity using inhibition zone assays. Proteins/peptides fraction in all vernix extracts exhibited a clear and strong antibacterial activity [inhibition of growth on nutrient agar] against Klebsiella pneumoniae, Staphylococcus aureus and Streptococcus pyogenes, in addition to antifungal activity against Candida albicans. Alpha- defensins [HNP1-3], LL-37 and lysozyme were characterized among the active components. In addition, psoriasin and ubiquitin were identified in fractions derived from vernix, that exhibited antibacterial activity