Pro-fibrotic biomarkers in ex vivo lung tissue slices: A species comparison

Pulmonary fibrosis is a severe and fast progressing lung disease causing irreversible dysfunction of the organ. Current treatments are accompanied by severe side effects and do not accomplish final cure of the disease. With the use of fresh lung tissue, the aim was to identify specific biomarkers of pulmonary fibrosis ex vivo in order to improve the investigation of novel pharmacological approaches. Vital tumor-free lung tissue was used to prepare human ex vivo tissue slices. Slices were cultured in the presence of TGF-β and TNF-α to induce a pro-fibrotic profile. Rat tissue slices were prepared from lungs of bleomycin-treated rats and were cultivated in medium only. Human tissue slices stimulated ex vivo with TGF-β and TNF-α displayed an up-regulation of important pro-fibrotic genes as compared to control samples. Amongst others, mRNA levels of matrix metalloproteinase 13 were 2- to 6-fold and the extracellular enzyme lysil oxidase was 2- to 3-fold elevated. Other genes, e.g caveolin-1 were downregulated in the presence of TGF-β and TNF-α. Tissue slices prepared from bleomycin treated rats revealed a comparable pattern of up-regulated pro-fibrotic genes. Here, e.g. mRNA levels of collagen1a1 or fibronectin 1 were significantly up-regulated as compared to control samples. Moreover, this pattern shows stable expression in culture for 2 to 5 days. Comparison of the mRNA profiles from both species, by using INGENUITY pathway analysis software, revealed identical canonical pathways and upstream regulators. This characteristic pattern of pro-fibrotic biomarkers, described in ex vivo lung tissue slices from two different species, enables the investigation of pulmonary fibrosis with high translational relevance.