Detection and Characterisation of Transforming Growth Factor-Beta in Porcine Colostrum

Abstract

Porcine colostrum and milk collected at different stages of lactation were assessed for transforming growth factor-β (TGF-β) activity using an epithelial cell bio-assay. A high level of TGF-β activity was recorded in all colostrum samples after transient acidification treatment, ranging between 126 and 260 ng/ml for samples collected at the time of parturition and 73 ng/ml for the sample collected 12 h after parturition. Without transient acidification treatment TGF-β activity was detected only in 2 samples collected at the time of parturition (12 ng/ml) and 12 h after parturition (9 ng/ml), respectively. TGF-β activity was undetectable in milk collected 5 days after parturition. These results suggest that TGF-β exists mainly in latent form in porcine colostrum and the concentration declines rapidly as lactation proceeds. After enrichment with cation exchange chromatography a low level of TGF-β activity was detected in porcine milk. Further separation by size exclusion chromatography revealed two molecular mass forms of TGF-β in both colostrum and milk samples, a major peak of about 80 kD and a minor peak of about 25 kD representing latent and active forms of TGF-β, respectively. A further experiment showed that the latent form of TGF-β in colostrum can be activated at pH 3.5 or less. It is speculated that TGF-β found in the colostrum may play a physiological role in regulating postnatal adaptation of the gastro-intestinal tract in new borns.

Preterm human milk contains a large pool of latent TGF-β, which can be activated by exogenous neuraminidase

“…At these time points, most TGF-␤ was in a latent form, which is consistent with earlier observations in human and animal milk by Srivastava et al (66), Nakamura et al (45), Rogers et al (60), Pakkanen (50), and Xu et al (71). In our study, we detected increased latent TGF-␤ at later time points.…”

Mammary Epithelial Cells Treated Concurrently with TGF-α and TGF-β Exhibit Enhanced Proliferation and Death

“…However, cultures treated with 2.5 ng/ml and 10 ng/ml TGF-b1 significantly inhibited NOG-8 cell growth through Day 6 relative to controls (P , 0.0007; data not shown). Thus, 10 ng/ml TGF-a and 2.5 ng/ml TGF-b1 were used for all subsequent experiments, as these were the minimal concentrations that significantly affected epithelial growth rate and fell within reported physiologic concentrations (45,46).…”

Oral ingestion of colostrum alters intestinal transforming growth factor-beta receptor intensity in newborn pigs

“…The concentrations of these bioactive compounds are usually high in colostrum, decline rapidly in mature milk (Xu, 2003) and are often below the detection level in infant formula (Lo and Kleinman, 1996). For example, TGF-β concentration in porcine colostrum collected at the time of parturition ranged between 126 and 260 ng/ml; it declined to 72 ng/ml 12 h after parturition, and became undetectable in milk collected 5 days after parturition (Xu et al, 1999).…”

“…TGF-β has been found in the colostrum of various species (Saito et al, 1993;Pakkanen, 1998;Penttila et al, 1998;Xu et al, 1999) and may play an important role in postnatal adaptation of the gastrointestinal tract in suckling animals (Xu et al, 2000). TGF-β exerts its biological actions through interactions with cell surface transmembrane receptor complex consisting of RI, RII and RIII (Massague, 1998).…”