AB0155 THE ULTRASTRUCTURAL FEATURES OF INTERSTITIAL LUNG TISSUE INVOLVEMENT DUE TO SYSTEMIC SCLEROSIS: ANIMAL EXPERIMENTAL STUDY
Authors: B. Doskaliuk, L. Zaiats, R. Yatsyshyn
Journal: Annals of the Rheumatic Diseases (2020)

Background: Systemic sclerosis (SSc) - is an autoimmune connective tissue disease, which crucial role is played by inflammation and fibrosis development. This pathology is characterized by multiple symptoms that occur due to alterations of the vascular wall, limited or widespread fibrosis of the dermis and visceral organs, dysregulation of cellular and humoral immunity, followed by the formation of autoantibodies specific to the structures of the organism. Although external manifestations of SSc certainly lead to a decrease in the functional activity and patient’s quality of life up to disability, the real danger is a violation of the functions of the internal organs and systems. Objectives: The aim of our study was to determine changes in the morphological structure of lung interstitial tissue at the subcellular level of the structural organization, which were achieved by modeling of this autoimmune pathology in laboratory animals. Methods: The main concept of modeling process was based on the previously described method of SSc induction [1,2] however with some differences from original model. Into the study were involved 30 pubescent Wistar rats (220-240g) who underwent a three times a week subcutaneous administration of 0.5ml of 5% sodium hypochlorite (NaClO) solution with active chlorine concentration of 190 g/dm 3 for 6 weeks in a row; control group (20 rats) that received injections with an equal volume of sterile saline solution. After 8 weeks from the beginning of the experiment animals were sacrificed under thiopental anesthesia, lung tissue specimens were obtained, fixed alternately in 2.5% glutaraldehyde and in 1% solution of osmium tetroxide. After dehydration, the material was embedded in Epon-Araldite. Sections were obtained on an ultramicrotome (Tesla BS-490) magnification x9600 was performed on high-resolution microscope (PEM-125K). Results: The ultrastructural study of lung specimens reviled the fibroblasts with high amounts of collagen fibers in the interstitial tissue of the alveoli wall. Fibroblast nuclei were characterized by irregular shape and numerous invaginations of the nuclear envelope and marginal aggregation of chromatin granules. Fig. 1 depicts the fragment of the alveolar wall of the lungs of white Wistar rats in 8 weeks after the start of the experiment. On the Fig. 1 could be distinguished the lumen of the alveoli (1), fibroblast (2) with increased quantity of collagen fibers (3) and a peripheral part of alveolocyte I type (4). Figure 1. Conclusion: The current findings confirm the efficacy of NaСlO chemical model of reproduction of interstitial lung tissue involvement within SSc pathogenesis; this model could contribute to the further investigation of peculiarities of autoimmune origin interstitial lung disease (ILD). References: [1]Servettaz A, Goulvestre C, Kavian N, Nicc, C, Guilpain P, Chéreau C, Batteux F. Selective oxidation of DNA topoisomerase 1 induces systemic sclerosis in the mouse. The Journal of Immunology. 2009; 182(9), 5855-5864. [2]Batteux F, Kavian N, Servettaz A. New insights on chemically induced animal models of systemic sclerosis. Current opinion in rheumatology. 2011; 23(6), 511-518. Disclosure of Interests: None declared