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Collagen synthesis during lung development and during hyaline membrane disease in the nonhuman primate
J C Jackson1, J G Clark, T A Standaert
1Department of Pediatrics, University of Washington, Seattle 98195.
Insights
Premature infants show higher lung collagen synthesis rates than term infants or adults. Hyaline membrane disease (HMD) in premature infants does not further increase collagen synthesis beyond growth-related levels.
Area of Science:
- Biochemistry
- Developmental Biology
- Pulmonology
Background:
- Collagen synthesis is crucial for lung development and repair.
- Maturational changes in collagen synthesis are not fully understood.
- Hyaline membrane disease (HMD) affects premature infants, impacting lung function.
Purpose of the Study:
- To investigate maturational changes in lung collagen synthesis rates.
- To determine if premature infants have altered collagen synthesis compared to older animals.
- To assess if HMD exacerbates collagen synthesis in premature lungs.
Main Methods:
- Lung tissue samples were collected from Macaca nemestrina monkeys across various developmental stages (gestation to adulthood).
- Rates of total protein and collagen synthesis were measured using [3H]proline incorporation and proline to hydroxyproline conversion.
- Collagen synthesis rates were compared between premature, term, and adult monkeys, including those with and without HMD.
Main Results:
- Premature monkeys exhibited significantly higher collagen synthesis rates (9.9 nmol/mg DNA/h) compared to term infants (5.3 nmol/mg DNA/h) and adults (2.1 nmol/mg DNA/h).
- Infants with HMD did not show an additional increase in collagen synthesis rate during the first week of life.
- Collagen synthesis rates remained stable in control premature animals throughout the first week.
Conclusions:
- Lung collagen synthesis is elevated in premature infants, likely supporting lung growth.
- The early recovery phase of HMD in premature infants does not involve a further surge in collagen production.
- These findings highlight the dynamic nature of collagen synthesis during lung development and its response to prematurity.
Abstract:
To assess maturational changes in collagen synthesis, lung tissue was obtained from healthy Macaca nemestrina monkeys at different ages, ranging from 68% of term gestation to adulthood. We hypothesized that infants delivered prematurely have a greater rate of collagen synthesis than do older animals because of their greater rate of lung growth during gestation. Secondly, we hypothesized that lung repair in infants with hyaline membrane disease (HMD) is associated with an additional increase in lung collagen synthesis rate. Therefore, lung tissue was obtained during the first week of life from monkeys delivered at 82% of term gestation, a stage at which half of them developed HMD. The rate of total protein synthesis in lung samples was determined by measuring the incorporation of [3H]proline; the rate of collagen synthesis was determined by measuring the conversion of proline into hydroxyproline. Premature monkeys had a higher rate of collagen synthesis (9.9 +/- 2.7 nmol/mg DNA/h) than did term infants (5.3 +/- 1.1) or older animals (2.1 +/- 0.4, p less than 0.05). There was no additional increase in rate of collagen synthesis in animals with HMD from 3 h (14.3 +/- 6.9) to 7 days of age (15.1 +/- 6.1); control premature animals also had no significant change during the first week of life (10.9 +/- 3.0 at 3 h; 11.6 +/- 4.6 at 7 days). The early stage of recovery from HMD in premature monkeys does not appear to be associated with an increase in collagen production beyond the already increased synthesis rate associated with lung growth.