Background. Interstitial lung disease (ILD) is a pathology that can often be diagnosed in patients with systemic sclerosis (SSc).  Its development may result in a significant decrease in the quality of life of patients.

Aim. To assess the changes in the microcirculatory hemocapillars in the lungs in the experimentally induced SSc.

Methods. The experiment involved a control group (CG) (20 animals) and an experimental group (EG) (25 animals) formed by mature Wistar line laboratory rats, 180-220g of weight. The SSc was modeled in the EG using sodium hypochlorite (NaClO) by the method we reported earlier [Doskaliuk B et al. Annals of the Rheumatic Diseases 2021;80:1074]. The isotonic solution was administered to control animals by the same scheme. After 8 weeks lung tissue specimens were sampled and stained with hematoxylin and eosin (H&E). Magnification x200 (Leica DM750).
 
Results. Histological analysis of lung tissue specimens of animals from EG showed a violation of the structure of the hemocapillaries of the lungs. We observed narrowing of the lumen of microvessels due to thickening of vascular wall caused by swelling and perivascular infiltration by polymorphonuclear cells. The histological analysis of lung specimens obtained from control group was normal.
 
Conclusion. This study verified the presence of disturbance of a structural architecture of the microcirculatory bed of lungs in case of experimentally induced systemic sclerosis.