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Sequence of inflammatory cell migration into lung during recovery from hyaline membrane disease in premature newborn
Abstract:
The appearance of polymorphonuclear leukocytes (PMN) and macrophages (MAC) in lung during the development of hyaline membrane disease (HMD) may be important in lung injury and repair. These inflammatory cells may cause additional lung injury during recovery from HMD and contribute to the development of bronchopulmonary dysplasia (BPD). By morphometric methods, we compared the proportion of PMN and MAC in lung tissue of premature M. nemestrina monkeys with HMD to the proportion of these cells in the lungs of healthy control animals of a similar postnatal age and to fetuses of the same gestational age. Expressed as a fraction of all lung cells, healthy premature control monkeys have the same %PMN and %MAC in lung tissue as fetal animals. However, during the development of acute HMD, there is an increase in %PMN (p less than 0.05), but not in %MAC, compared to fetal animals. During recovery, there is a greater than 10-fold increase in %MAC (p less than 0.02), but no significant additional increase in %PMN compared to animals with acute HMD. We conclude that the sequence of inflammatory cell migration into the premature lung injured during HMD is first a polymorphonuclear one, followed by entry of macrophages. Control of this inflammatory response during recovery from HMD may play a role in the pathogenesis of BPD.
Insights
Inflammatory cells, including polymorphonuclear leukocytes (PMN) and macrophages (MAC), play a role in lung injury and repair during hyaline membrane disease (HMD). Their sequential appearance in the premature lung may influence the development of bronchopulmonary dysplasia (BPD).
Area of Science:
- Pulmonary Medicine
- Neonatology
- Immunology
Background:
- Hyaline membrane disease (HMD) is a significant respiratory disorder in premature infants.
- Inflammatory cells, specifically polymorphonuclear leukocytes (PMN) and macrophages (MAC), are implicated in lung injury and repair processes.
- The role of these inflammatory cells in the pathogenesis of bronchopulmonary dysplasia (BPD) following HMD requires further elucidation.
Purpose of the Study:
- To compare the proportions of PMN and MAC in the lungs of premature nonhuman primates with HMD to healthy controls and fetuses.
- To investigate the temporal sequence of inflammatory cell infiltration during acute HMD and recovery.
- To assess the potential contribution of inflammatory cell dynamics to the development of BPD.
Main Methods:
- Morphometric analysis of lung tissue from premature M. nemestrina monkeys.
- Comparison of PMN and MAC proportions in animals with HMD, healthy controls, and fetuses.
- Statistical analysis to determine significant differences in cell populations.
Main Results:
- Healthy premature lungs showed similar PMN and MAC proportions to fetal lungs.
- Acute HMD led to an increased percentage of PMN, but not MAC, compared to fetuses.
- During recovery from HMD, a significant increase in MAC (over 10-fold) was observed, with no further increase in PMN.
Conclusions:
- The inflammatory response in the premature lung during HMD involves a sequential infiltration of PMN followed by MAC.
- The observed inflammatory cell dynamics during HMD and recovery may be critical in the pathogenesis of BPD.
- Modulating this inflammatory response during recovery could be a therapeutic target for preventing BPD.
