A potential role for endothelial adhesion molecules and cytokines in chemotherapy-induced lung fibrosis

Bleomycin (BLM)-induced pulmonary fibrosis, a side-effect of BLM therapy, is associated with pulmonary immune cell infiltration, which may contribute to fibrogenesis. Previous work suggests BLM may induce endothelial cell (EC) adhesion molecule and cytokine expression which may recruit leukocytes. However, the full profile of adhesion molecules and cytokines expressed by ECs treated with physiological BLM concentrations is uncertain; this work aims to characterise this profile. Adhesion molecule and cytokine expression by BLM-treated HUVECs was assessed by flow cytometry and ELISA, and confirmed by qPCR. Whether physiological TNF-α concentrations “primed” HUVECs and increased adhesion molecule expression was also assessed. HUVECs were also treated with etoposide, doxorubicin, and carboplatin, to determine whether observed effects were unique to BLM. HUVECs treated with BLM were seen to express higher levels of ICAM-1, VCAM-1, E-selectin, IL-8, and MCP-1. qPCR results confirmed that expression was regulated at a transcriptional level, suggesting BLM is not a cytokine secretagogue. However, co-treatment with TNF-α and BLM did not impact adhesion molecule expression. Further, only etoposide increased E-selectin, ICAM-1, and IL-8 expression, suggesting BLM is not unique in inducing an inflammatory phenotype in HUVECs. These results suggest the effects of BLM on ECs may induce pulmonary immune cell recruitment, as may the effects of etoposide, which has also been associated with lung fibrosis. Future work will assess the functional relevance of this expression and whether pulmonary microvascular ECs respond to BLM in a similar fashion.