Compositions for treating or preventing respiratory tract infections and method of use thereof

1. A method of decreasing susceptibility to a respiratory tract infection in a preterm neonate subject in need thereof, wherein the subject is further in need of improved lung surfactant homeostasis, the method comprising, administering to the subject a composition comprising granulocyte-macrophage colony stimulating factor (GM-CSF) or a functional homologue thereof via pulmonary airway administration.

2. The method of claim 1 , wherein the GM-CSF or a functional homologue thereof is administered at birth or shortly thereafter.

3. The method of claim 2 , wherein shortly after birth is within about 1 minute, within about 2 minutes, within about 3 minutes, within about 4 minutes, within about 5 minutes, within about 10 minutes, within about 15 minutes, within about 20 minutes, within about 25 minutes, within about 30 minutes, within about 35 minutes, within about 40 minutes, within about 45 minutes, within about 50 minutes, within about 55 minutes, within about 1 hour, within about 2 hours, within about 3 hours, within about 4 hours, within about 5 hours, within about 6 hours, within about 7 hours, within about 8 hours, within about 9 hours, within about 10 hours, within about 11 hours, within about 12 hours, within about 13 hours, within about 14 hours, within about 15 hours, within about 16 hours, within about 17 hours, within about 18 hours, within about 19 hours, within about 20 hours, within about 21 hours, within about 22 hours, within about 23 hours, or within about 24 hours after birth.

4. The method of claim 1 , wherein the GM-CSF or a functional homologue thereof is administered by intratracheal, intrabronchial or intraalveolar administration.

5. The method of claim 1 , wherein the subject is administered a nebulized aerosol, nebulized solution or inhaled powder form of GM-CSF or a functional homologue thereof.

6. The method of claim 1 , wherein the GM-CSF or functional homologue thereof is administered at birth and at least one time shortly thereafter.

7. The method of claim 1 , wherein the susceptibility of infection in the subject is reduced relative to a subject with pulmonary dysfunction resulting from impaired AM development and has not been treated with GM-CSF or a functional homologue thereof.

8. The method of claim 1 , wherein the respiratory tract infection is bacterial pneumonia.

9. A method of treating a preterm neonate subject having or suspected of having pulmonary dysfunction, wherein the subject is in need of improved lung surfactant homeostasis, the method comprising, administering to the subject a composition comprising granulocyte-macrophage colony stimulating factor (GM-CSF) or a functional homologue thereof via pulmonary airway administration.

10. The method of claim 9 , wherein the GM-CSF or a functional homologue thereof is administered at birth or shortly thereafter.

11. The method of claim 10 , wherein shortly after birth is within about 1 minute, within about 2 minutes, within about 3 minutes, within about 4 minutes, within about 5 minutes, within about 10 minutes, within about 15 minutes, within about 20 minutes, within about 25 minutes, within about 30 minutes, within about 35 minutes, within about 40 minutes, within about 45 minutes, within about 50 minutes, within about 55 minutes, within about 1 hour, within about 2 hours, within about 3 hours, within about 4 hours, within about 5 hours, within about 6 hours, within about 7 hours, within about 8 hours, within about 9 hours, within about 10 hours, within about 11 hours, within about 12 hours, within about 13 hours, within about 14 hours, within about 15 hours, within about 16 hours, within about 17 hours, within about 18 hours, within about 19 hours, within about 20 hours, within about 21 hours, within about 22 hours, within about 23 hours, or within about 24 hours after birth.

12. The method of claim 9 , wherein the GM-CSF or a functional homologue thereof is administered by intratracheal, intrabronchial or intraalveolar administration.

13. The method of claim 9 , wherein the subject is administered a nebulized aerosol, nebulized solution or inhaled powder form of GM-CSF or a functional homologue thereof.

14. The method of claim 9 , wherein the GM-CSF or functional homologue thereof is administered at birth and at least one time shortly thereafter.

15. The method of claim 9 , wherein administration of GM-CSF or a functional homologue thereof results in increased alveolar macrophage or alveolar macrophage precursor proliferation.

16. The method of claim 9 , wherein administration of GM-CSF or a functional homologue thereof results in improved lung surfactant homeostasis.

17. The method of claim 16 , further comprising measuring the levels of one or more of surfactant protein-D and surfactant protein-A to determine improved lung surfactant homeostasis.

18. The method of claim 17 , wherein the level of surfactant protein-D is reduced relative to a subject with pulmonary dysfunction resulting from impaired alveolar macrophage (AM) development.