Abstract
BackgroundColostrum, the milk produced during first few days after birth, is rich in immunoglobulins, antimicrobial peptides & growth factors. Multiple clinical trials using bovine colostrum are ongoing but with no assessment of test product bioactivity.ObjectivesTo examine variability of bioactivity between 20 commercial colostrum products, contribution of TGFβ and EGFR in mediating effects, heat sensitivity of bioactivity and changes in bioactivity of colostrum milkings in the days following calving.DesignIn vitro bioactivity used AGS, RIE-1 and Caco-2 cell proliferation (Alamar blue) and migration (wounded monolayers) assays. Changes in colostrum bioactivity determined following addition of TGFβ-neutralising antibody, EGFR blocker (Typhostin) and after heating (40–60°C, 60 min). In vivo bioassay assessed ability of colostrum gavage (2ml, 7mg/ml) to reduce gastric damage (NSAID + restraint) in rats. Milkings from 6 cows, days 0–3 post calving were assessed for bioactivity and growth factor concentrations.ResultSix-fold differences in pro-proliferative and migratory activity were seen comparing commercial products. Comparison of most- and least-active samples from in vitro studies showed two- to three-fold differences in ability to reduce gastric injury (86% reduction using most-active vs 48% using least-active, p<0.01). Tyrphostin reduced pro-migratory and proliferative activity by 23% and 55%. TGFβ neutralisation reduced migratory activity by 83% but did not affect proliferation Heating colostrum powder to 50°C did not affect immunoactivity of haptoglobin, EGF, TGFβ, IgG, IGF-1 or betacellulin but decreased bioactivity by >40%. Milking studies showed high bioactivity during first and second milkings on day 0 but 77% reduction by day 3. Changes in total protein, haptoglobin, EGF, TGFβ, IgG and IGF-1 paralleled falls in bioactivity.ConclusionCommercial colostrum products possess widely different bioactivity. Variation in heat exposure and/or proportion of day 0 colostrum content may contribute to this. Assessment of colostrum bioactivity has advantages to growth factor quantitation for quality control.
Highlights
Colostrum is the specific first diet of mammalian neonates and is rich in immunoglobulins, antimicrobial peptides e.g. lactoferrin, and other bioactive molecules including growth factors such as transforming growth factor-beta (TGFβ) and insulin-like growth factor-1 (IGF-1) [1]
2) Having found major variation exists, we studied the most and least active colostrum samples using an in vivo model of gastric damage to examine if differences seen in vitro had pathophysiological-therapeutic relevance 3) We studied an exemplar colostrum sample in more detail to determine the importance of the Epidermal growth factor receptor (EGFR) and Transforming growth factor beta (TGFβ) pathways in mediating its proliferative and migratory effects and whether exposing the colostrum
Gastric damage is induced through the combination of the toxic Nonsteroidal anti-inflammatory drugs (NSAID) effects of the indomethacin which is enhanced by the short-term (3 hour) stress of restraint [19]
Summary
Colostrum is the specific first diet of mammalian neonates and is rich in immunoglobulins, antimicrobial peptides e.g. lactoferrin, and other bioactive molecules including growth factors such as transforming growth factor-beta (TGFβ) and insulin-like growth factor-1 (IGF-1) [1]. Multiple clinical trials using bovine colostrum are ongoing but with no assessment of test product bioactivity These studies examined variation in bioactivity between different commercial samples using in vitro models of the early stages of gut repair i.e. cell migration and proliferation. Samples were subsequently diluted to 1 mg powder/ml and analysed using proliferation and migration assays and for growth factor immunoactivity. To show that protein concentration had not been altered by the heating, protein concentration of samples was determined before and after using BCA assay
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