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Postnatal undernutrition slows development of bronchiolar epithelium in rats
G D Massaro1, L McCoy, D Massaro
1Pulmonary Research Laboratories, Calvin and Flavia Oak Asthma Research and Treatment Facility, University of Miami School of Medicine 33136.
Insights
Early life undernutrition in rats delayed the development of bronchiolar Clara cells and altered small airway epithelium composition. These changes persisted, indicating long-term effects on lung structure from early nutrition.
Area of Science:
- Pulmonary Medicine
- Developmental Biology
- Cell Biology
Background:
- Small conducting airways are crucial for lung function and are affected early in chronic lung diseases.
- Childhood environmental factors can negatively impact adult small airway function.
- The early postnatal period is critical for bronchiolar epithelium development in rats.
Purpose of the Study:
- To investigate the impact of early postnatal undernutrition on the anatomical development of the rat bronchiolar epithelium.
- To determine if nutritional deficits during a critical developmental window lead to lasting changes in airway cell structure and composition.
Main Methods:
- Undernutrition was induced in rats by increasing litter size shortly after birth.
- The study assessed the development of mitochondria and rough endoplasmic reticulum in bronchiolar Clara cells.
- Changes in cell mitosis, nuclear density of ciliated cells, and cell conversion were quantified.
Main Results:
- Early postnatal undernutrition delayed the maturation of mitochondria and rough endoplasmic reticulum in Clara cells.
- Underfeeding led to significantly reduced Clara cell mitosis and decreased ciliated cell nuclear density.
- An abnormal small airway epithelium cellular composition was observed, persisting long after the underfeeding period.
Conclusions:
- Early neonatal nutritional deficits can profoundly and persistently alter the anatomical development of the bronchiolar epithelium.
- These findings highlight the long-term consequences of early life events on lung structure and function.
- Neonatal nutrition is a critical factor influencing the long-term health of the small airways.
Abstract:
The lung's small conducting airways are sites of dysfunction early in the course of chronic lung diseases that are prevalent in humans; furthermore, there is evidence that aspects of childhood environment may adversely influence small airway function in adulthood. Because there is considerable early postnatal morphological maturation of the bronchiolar epithelium in rats, these considerations led to the present study in which we assessed the effect of early postnatal undernutrition in rats on the anatomic development of the bronchiolar epithelium. We found undernutrition, produced by increasing rat litter size shortly after birth, led to delayed development of the mitochondria and rough endoplasmic reticulum of bronchiolar Clara cells. Of particular interest, underfeeding resulted in considerably diminished mitosis by Clara cells, decreased nuclear numerical density of bronchiolar ciliated cells, evidence of diminished conversion of Clara cells to ciliated cells, and an abnormal cellular composition of the small airway epithelium that persisted well beyond the period of underfeeding. We conclude that early neonatal events can have long-term effects on the bronchiolar epithelium.