Alveolar–capillary barrier alteration due to systemic sclerosis: an experimental study

Abstract

Background: Systemic sclerosis (SSc) is frequently linked with a pulmonary involvement. SSc-associated pulmonary disorders are characterized by a considerable negative impact on survival and life quality of patients.

Aim: To establish structural changes in the morphology of blood-air barrier due to experimentally induced SSc.

Methods: The experimental reproduction of SSc was provided using animal model. 30 Wistar rats (220-240g) were involved into our study. They underwent subcutaneous administration of 0.5ml of 5% sodium hypochlorite (NaClO) solution three times a week for 6 weeks in a row. There were 15 rats in a control group. After 8 weeks all animals were euthanized, and lung tissue sections were obtained on an ultramicrotome (Tesla BS-490). Magnification x9600 was performed with the help of high-resolution microscope (PEM-125K).

Results: Ultrastructural analysis revealed that the nuclei of many type I pneumocytes were with a matrix of low electron-optical density and marginal aggregation of chromatin granules. The nuclear membrane had wavy contours and forms superficial invagination. Mitochondria were enlarged with single reduced cristae. In some cells destruction of cristae was observed. Along with the expanded cisternae of Golgi apparatus the fragmentation of membranes of rough endoplasmic reticulum was defined. The basement membrane was thickened and with fuzzy contours. In the peripheral parts of single cells there were local ruptures of the apical plasmolemma, which lead to the release of intracellular contents into the lumen of the alveoli.

Conclusions: It was shown that SSc is accompanied by severe violations of the ultrastructural organization of type I pneumocytes.