Effect of the vitamin B12-binding protein haptocorrin present in human milk on a panel of commensal and pathogenic bacteria

Abstract

BackgroundHaptocorrin is a vitamin B12-binding protein present in high amounts in different body fluids including human milk. Haptocorrin has previously been shown to inhibit the growth of specific E. coli strains, and the aim of the present study was to elucidate whether the antibacterial properties of this protein may exert a general defense against pathogens and/or affect the composition of the developing microbiota in the gastrointestinal tracts of breastfed infants.FindingsThe present work was the first systematic study of the effect of haptocorrin on bacterial growth, and included 34 commensal and pathogenic bacteria to which infants are likely to be exposed. Well-diffusion assays addressing antibacterial effects were performed with human milk, haptocorrin-free human milk, porcine holo-haptocorrin (saturated with B-12) and human apo-haptocorrin (unsaturated). Human milk inhibited the growth of S. thermophilus and the pathogenic strains L. monocytogenes LO28, L. monocytogenes 4446 and L. monocytogenes 7291, but the inhibition could not be ascribed to haptocorrin. Human apo-haptocorrin inhibited the growth of only a single bacterial strain (Bifidobacterium breve), while porcine holo-haptocorrin did not show any inhibitory effect.ConclusionsOur results suggest that haptocorrin does not have a general antibacterial activity, and thereby contradict the existing hypothesis implicating such an effect. The study contributes to the knowledge on the potential impact of breastfeeding on the establishment of a healthy microbiota in infants.

Cobalamin and haptocorrin in human milk and cobalamin-related variables in mother and child: a 9-mo longitudinal study

“…A few studies point to an antimicrobial effect of HC in the intestine of infants, where HC, by withholding cobalamin, potentially protects the infant against pathogenic bacteria (23,24). However, a recent systematic study of 34 strains of microorganisms present in the intestine of infants could not support this hypothesis (25). Another hypothesis is that HC mediates cobalamin absorption by being a "stand-in" for an immature intrinsic factor-mediated absorption in early infancy (26).…”

Influence of Maternal Milk on the Neonatal Intestinal Microbiome

“…Hypothiocyanite exhibits its anti-bacterial property by decreasing the viability of bacteria, viruses, and fungi [99]. Haptocorrin is a Vitamin B12 binding protein, previously shown to inhibit the growth of bacteria, but more recent studies have shown that the bactericidal/bacteriostatic activity could not be attributed to haptocorrin alone, so perhaps haptocorrin functions in concert with other anti-bacterial mediators [100].…”

The Functional Power of the Human Milk Proteome

“…Same holds true for haptocorrin, as the major vitamin B 12 binding protein, normally unsaturated in human milk, to withhold vitamin B 12 and inhibit the growth of bacteria [122]. However, haptocorrin does not have a general antibacterial activity, rather its activity was found for a single enteropathogenic Escherichia coli ( E. coli ) O127 strain (EPEC) [123] and Bifidobacterium breve [124].…”