Mouse major histocompatibility complex (H-2) and fetal lung development: implications for human pulmonary maturation

Area of Science:

• Developmental Biology
• Immunogenetics
• Pulmonary Medicine

Background:

• Lung maturation is a complex process influenced by genetic and hormonal factors.
• The Major Histocompatibility Complex (MHC), specifically the H-2 complex in mice, plays a critical role in immune responses and has been implicated in developmental processes.
• Endogenous corticosteroids are crucial for accelerating fetal lung maturation.

Purpose of the Study:

• To investigate the role of genes within or near the H-2 complex in mouse lung development and corticosteroid responsiveness.
• To examine endogenous pulmonary corticosterone levels during fetal development in different H-2 congenic mouse strains.
• To assess the impact of maternal H-2 haplotype on fetal lung maturation and response to exogenous corticosteroids.

Main Methods:

• Utilized C57/10Sn (B10, H-2b) and B10.A/SgSn (B10.A, H-2a) congenic mice for comparative studies.
• Measured endogenous pulmonary corticosterone levels throughout gestation in fetal mice.
• Assessed lung morphological maturation using morphometry on gestation day 17, with and without corticosteroid treatment.
• Analyzed heterozygous offspring from reciprocal crosses to evaluate maternal effects and H-2 haplotype influence.

Main Results:

• Endogenous pulmonary corticosterone levels increased progressively during gestation in both B10 and B10.A mice, with similar amounts detected in both strains.
• B10.A (H-2a) mouse lungs exhibited less morphological maturation compared to B10 (H-2b) lungs at gestation day 17.
• Corticosteroid treatment significantly enhanced lung maturation in H-2a mice, making them equal to or more mature than H-2b mice.
• Maternal H-2 haplotype influenced fetal lung maturation, with a maternally derived H-2a haplotype associated with less mature lungs.
• All heterozygous offspring showed increased lung maturity upon exogenous corticosteroid administration, irrespective of the H-2 haplotype's origin.

Conclusions:

• Genes located at or near the H-2 complex are associated with progressive lung maturation in mice.
• The H-2 complex also influences the fetal lung's ability to respond to corticosteroid treatment.
• Maternal genetic factors, potentially linked to the H-2 complex, play a role in regulating normal lung development and corticosteroid sensitivity.