Qualitative Histopathological Analysis of Bleomycin-Induced Lung Injury

Abstract

Recent evidence has suggested that the accumulation of cholesterol-laden “fatty macrophages” in the lung may play a key role in the presentation of ALI 1, a condition that affects nearly 200,000 people per year in the United States. Studying the pathways of these cells suggests that preventing the formation and build-up of these macrophages could prevent many of the characteristic symptoms of acute lung injury. Specifically, this experiment aims to explore the effect that ACAT1 inhibition by K604 has on fatty macrophage formation and outcomes of ALI. To test this, different groups of mice were administered either PBS (as control), ITB (intratracheal bleomycin), PBS + K604, or ITB + K604. After the mice were sacrificed, the left lung lobes were extracted, inflated, embedded, and sectioned for microscopic scanning and analysis with the ImageJ software. The lung tissue was characterized using 3 unbiased parameters: alveolar wall thickness (µm), cell infiltration (number of nuclei), and percent white space. Simultaneously, a cholesterol assay was performed using cells extracted from mouse bronchoalveolar lavage (BAL). The results show that K604 was successful at preventing ITB-induced increases in cell infiltration, consolidation, and alveolar thickening as well as lipid accumulation in macrophages by limiting the formation of cholesterol esters through ACAT1 inhibition. In this respect, this experiment shows that K604 might be a viable pharmaceutical target in the treatment of ALI.