Abstract
Background: The protease inhibitors α 1-antitrypsin and antichymotrypsin are present in human milk, but little is known about their roles in protein digestion during infancy. It has been hypothesized that α 1-antitrypsin and antichymotrypsin may modulate digestion in the infant gut. Objective: We determined whether the mammary gland expresses α 1-antitrypsin and antichymotrypsin, measured α 1-antitrypsin and antichymotrypsin throughout lactation, assessed the resistance of α 1-antitrypsin to proteolysis, and determined the potential of α 1-antitrypsin to affect the survival of other milk proteins. Design: A pool of complementary DNA from the human mammary gland was analyzed with polymerase chain reaction to detect genes for α 1-antitrypsin and antichymotrypsin. α 1-Antitrypsin and antichymotrypsin concentrations were measured in milk samples obtained longitudinally (days 4-47) from 8 women. An in vitro model of infant digestion was used to assess the digestive stability of α 1-antitrypsin against pepsin and pancreatin. Lactoferrin, with α 1-antitrypsin present, was digested by pancreatin, and the digested proteins were separated. Results: α 1-Antitrypsin and antichymotrypsin concentrations were high in early milk and decreased throughout lactation. Polymerase chain reaction products were detected for both genes. After in vitro digestion, much of the α 1-antitrypsin was still intact, whereas many other milk proteins were digested. Much of the lactoferrin was still intact after digestion, but only when α 1-antitrypsin was added. Conclusions: The results suggest that α 1-antitrypsin and antichymotrypsin are produced by the mammary gland and are present in milk in relatively high amounts in early lactation. α 1-Antitrypsin may survive digestion and may affect the survival of other proteins.
Original language | English (US) |
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Pages (from-to) | 828-833 |
Number of pages | 6 |
Journal | American Journal of Clinical Nutrition |
Volume | 76 |
Issue number | 4 |
State | Published - Oct 2002 |
Keywords
- α -Antitrypsin
- Antichymotrypsin
- Breast milk
- Breast-feeding
- Human milk
- Infant digestion
- Mammary gland
- Milk proteins
- Protease inhibitors
ASJC Scopus subject areas
- Medicine (miscellaneous)
- Food Science