Biochimica et Biophysica Acta (BBA) - General Subjects
Human milk contains S100B protein
Introduction
S100B is an acidic calcium-binding protein originally isolated from the nervous system, where it is highly concentrated in glial cells, but later detected also in definite extra-nervous cell types [1]. Although many hypotheses have been formulated, the biological role of S100B is still a matter of debate. Among the different functions attributed to this protein, the possibility that it acts as a cytokine with a neurotrophic effect at physiological concentrations, essentially supported in experimental models on laboratory animals and cell cultures, appears interesting [1]. It is relevant, in this respect, that the caudo-rostral pattern of accumulation of the protein has been related to the biochemical, morphological and electrophysiological maturation of the human nervous system [2]. Recently, this hypothesis has also been supported in clinical studies demonstrating a correlation between S100B cord blood levels and physiological events related to brain maturation [3], [4].
The protein is known to be a normal constituent of human biological fluids, including cerebrospinal fluid, blood, urine and amniotic fluid [5], [6], [7]. Human milk is believed to contain biological factors involved in the regulation of newborn growth, including brain development [8], [9]. The present study investigates the presence of S100B in human milk to add to our knowledge regarding its distribution in biological fluids, which could also be useful to clarify the function of the protein.
Section snippets
Materials and methods
Breast milk samples for S100B protein assessment were drawn at day 5 from delivery from 16 women with consecutive singleton physiological pregnancies, whose deliveries were between 37 and 42 weeks' gestation. Exclusion criteria were: multiple pregnancies, gestational hypertension, diabetes and infections, fever, chromosomal abnormalities, metabolic diseases, diseases of the breast or central nervous system, and malnutrition.
The study protocol was approved by the Ethics Committee of the Giannina
Results
All mothers showed normal clinical conditions and no overt neurological injury and/or infections were observed at the sampling time-point or on discharge from the hospital.
All the samples investigated exhibited measurable levels of S100B, ranging from 62 to 212 μg/l (median 116.2 μg/l). Western blot analysis of milk samples (Fig. 1) using an anti-S100B rabbit antiserum revealed a major band that migrated with an apparent molecular mass comparable to that of purified ox brain S100B (lower than
Discussion
The present data constitute the first observation of the presence of S100B protein in breast milk. Western blot analysis confirms that the immunoreactivity observed using immunoluminometric assay reasonably refers to S100B protein and RT-PCR analysis also detects human S100B mRNA in the human milk.
These findings add milk to the list of biological fluids that contain this calcium-binding protein. The presence of a calcium-binding protein in a biological fluid such as milk, in which calcium is
Acknowledgements
This work was partially supported by Grants from Università Cattolica del S. Cuore to Fabrizio Michetti and from “Let's improve neonatal life” Foundation to Diego Gazzolo. We also thank Sangtec Medical, Bromma, Sweden, and Byk Gulden Italia for supplying analysis kits.
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Human milk and formulae: Neurotrophic and new biological factors
2012, Early Human DevelopmentCitation Excerpt :However, there is growing evidence that fatty acid content (PUFA, AA; EPA, DHE, etc.), per se, cannot be considered the only responsible of these strategical properties and the hypothesis that other molecules of extreme interest namely “trophic factors” could be involved in these development processes is to date consistent. These latter include neuro-oxidative stress biomarkers, neurotrophic proteins and calcium binding proteins [8,13–16] that are known to be involved in a cascade of events leading to brain, cardiac and vascular development/damage [8,13–19]. The present findings are also emphasized by the presence in human milk, at different periods of maturation, of highest concentrations of these trophic factors than on other biological fluids [i.e. cerebrospinal (CSF), blood, amniotic, urine] up to 20 times more [8,15,17–19].
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