[MODIFICATION OF ALVEOLAR MACROPHAGE POOL UNDER INFLUENCE OF PEPTIDE THERAPY IN THE BLEOMYCIN PNEUMOFIBROSIS MODEL]

Effect of peptide therapy on morphological and functional characteristics of alveolar macrophages and role of their phenotypic reprogramming in modulation of pulmonary fibrosing process were evaluated on the rat's model of pulmonary fibrosis, initiated by intratracheal administration of bleomycin. Status of alveolar macrophages was evaluated on the basis of electron microscopic studies and phagocytic activity. In lung tissue of control animals widespread diffuse interstitial fibrosis was determined. Alveolar macrophage cytoplasm was filled geterophagosomes with surfactant fragments, lipid droplets and cholesterol crystals; foam cells were a third of macrophage pool. After the course of peptide therapy the young cell with rare geterophagosomes and lipid droplets, without cholesterol crystals and increased phagocytic activity prevailed in macrophage population. There were rare sites of fibrosis in lungs; connective tissue contained much less collagen fibers than in the control; there was a growing proliferation of the bronchial epithelium. It may be assumed that under the influence of the peptide therapy a certain balance in the alveolar macrophage population was established with a predominance of M2 phenotype for the formation of the optimal ratio of cellular and humoral immune response, providing effective remedy of bronchial epithelium and prevention of lung tissue remodeling with the interstitial fibrosis formation.