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Development of gastrointestinal mucosal barrier. I. The effect of age on intestinal permeability to macromolecules
Insights
Newborns show increased intestinal antigen transport due to an underdeveloped gut barrier. This permeability significantly decreases after one week of age, impacting immune system development.
Area of Science:
- Gastroenterology
- Immunology
- Neonatal Physiology
Background:
- Indirect evidence suggests higher antigen penetration in newborns.
- Direct measurements of macromolecular transport across the perinatal intestinal mucosa are lacking.
Purpose of the Study:
- To directly measure intestinal macromolecular transport as a function of perinatal age.
- To investigate the development of the intestinal mucosal barrier in early life.
Main Methods:
- Administration of tritiated bovine serum albumin ([3H]BSA) via gavage to rabbits at various ages (birth, 1 wk, 2 wk, 6 wk, 1 yr).
- Measurement of plasma radioactivity 4 hours post-gavage.
- Quantification of plasma trichloroacetic acid insoluble radioactivity and immunoreactive [3H]BSA.
Main Results:
- Plasma radioactivity significantly decreased after one week of age.
- Adult rabbits showed less antigen transport compared to younger animals when adjusted for body weight.
- Newborns exhibit significantly higher intestinal transport of antigens.
Conclusions:
- The intestinal mucosal barrier is incompletely developed at birth in rabbits.
- Increased intestinal permeability in newborns facilitates greater antigen transport into the systemic circulation.
- Gut barrier function matures rapidly within the first postnatal week.
Abstract:
Indirect evidence has suggested that increased quantities of antigen may penetrate the intestinal mucosa and enter the systemic circulation during the newborn period compared to adult life. However, no direct measurement of macromolecular transport has been reported as a function of perinatal age. To study this process, we administered 100 mg of tritiated bovine serum albumin ([3H]BSA) by gavage to rabbits at birth, one wk, 2 wk, 6 wk, and one year of age and measured plasma radioactivity 4 hr after gavage. Plasma concentration of trichloroacetic acid insoluble radioactivity and immunoreactive bovine serum albumin radioactivity decreased significantly after one wk of age. When adult animals were gavaged with the same amount of [3H]BSA per body weight as the one-wk-old animals, they failed to transport as much of the antigen as the younger animals. This study, therefore, provides objective evidence that the intestinal mucosal barrier of newborns may be incompletely developed at birth and allow increased intestinal transport of antigens into the circulation.