Protective roles of pulmonary surfactant proteins, SP-A and SP-D, against lung allergy and infection caused by Aspergillus fumigatus.

Pulmonary surfactant proteins, SP-A and SP-D, are immune molecules which can directly interact with pathogens and allergens, stimulate immune cells and manipulate cytokine and chemokine profiles during host's immune response. Using an opportunistic fungal pathogen Aspergillus fumigatus (Afu), we have attempted to understand participation of SP-A and SP-D in the host immunity. Afu causes a systemic infection via lungs, called invasive aspergillosis (IPA) in immunocompromised subjects. In the immunocompetent subjects, it can cause an allergic disorder, called allergic bronchopulmonary aspergillosis (ABPA). Therapeutic administration of these proteins in a murine model of IPA can rescue mice from death. Treating mice, having ABPA, can suppress IgE levels, eosinophilia, pulmonary cellular infiltration and cause a marked shift from a pathogenic Th2 to a protective Th1 cytokine profile. These results highlight the potential of SP-A, SP-D and their recombinant forms, as novel therapeutics for lung allergy and infection.