Kinetics and biological function of transforming growth factor-β isoforms in bovine and human colostrum

초록

Colostrum contains various kinds of cytokines including TGF-beta that has potent regulatory effects on cells of the immune system. We compared the levels of TGF-beta1 and TGF-beta2 in bovine and human colostrum. Based on the isoform-specific ELISA, bovine colostrum collected on day I post-delivery retained 53.71 +/- 29.55 ng/ml of TGF-beta1 and 40.41 +/- 21.78 mug/ml of TGF-beta2 (n=4), while in human, 381.45 +/- 158.24 ng/ml of TGF-beta1 and 41.47 +/- 9.63 ng/ml of TGF-beta2 (n=5). Thus, dominant TGF-beta isoforms were completely opposite between human and bovine colostrum samples. The concentrations of both isoforms declined as lactation proceeded. Biological activities of the colostrum samples were determined using an MV1LU cell line. Consistent with the result from the immunoassay, TGF-beta1 in human and TGF-beta2 in bovine colostrum were responsible for the antiproliferative activity against MV1LU cells. Furthermore, bovine colostrum increased IgA secretion by LPS-stimulated mesenteric lymph node (MLN) cells, and this effect was abrogated by either anti-TGF-beta2 antibody or combined anti-TGF-beta1/beta2 antibody, but not by anfi-TGF-beta1 antibody alone. Similarly, TGF-beta2 in bovine colostrum enhanced the Ig germ line (GL) promoter activity, which is the earliest event toward IgA isotype switching. Taken together, these results suggest that TGF-beta isoforms, differentially expressed in human and bovine colostrum, may promote IgA isotype production in the neonatal intestine.

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