Bortezomib (BTZ), a chemotherapeutic drug used to treat multiple myeloma, induces life-threatening side effects, including severe pulmonary toxicity. However, the mechanisms underlying these effects remain unclear. The objectives of this study were to (1) investigate whether BTZ influences vascular permeability and (2) clarify the effect of BTZ on the expression of molecules associated with cell–cell junctions using human pulmonary microvascular endothelial cells in vitro. Clinically relevant concentrations of BTZ induced limited cytotoxicity and increased the permeability of human pulmonary microvascular endothelial cell monolayers. BTZ decreased the protein expression of claudin-5, occludin, and VE-cadherin but not that of ZO-1 and β-catenin. Additionally, BTZ decreased the mRNA expression of claudin-5, occludin, ZO-1, VE-cadherin, and β-catenin. Our results suggest that BTZ increases the vascular permeability of the pulmonary microvascular endothelium by downregulating cell–cell junction molecules, particularly claudin-5, occludin, and VE-cadherin.

Background/Aim: Aspergillus is often detected in respiratory samples from patients with chronic respiratory diseases, including pulmonary fibrosis, suggesting that it can easily colonize the airways. To determine the role of Aspergillus colonization in pulmonary fibrosis, we cultured human lung epithelial A549 cells or murine embryo fibroblast NIH/3T3 cells with Aspergillus conidia in 3D floating culture representing the microenvironment. Materials and Methods: Cells were cultured in two-dimensional (2D) and three-dimensional floating (3DF) culture with heat-inactivated Aspergillus fumigatus (AF) 293 conidia at an effector-to-target cell ratio of 1:10 (early-phase model) and 1:100 (colonization model), and RNA-sequencing and Western blots (WB) were performed. Results: AF293 conidia reduced A549 cell growth in 2D and 3DF cultures and induced apoptosis in A549 spheroids in 3DF culture. RNA-sequencing revealed the increased expression of genes associated with interferon-mediated antiviral responses including MX dymamin-like GTPase 1 (MX1). Interestingly, the decreased expression of genes associated with the cell cycle was observed with a high concentration of AF293 conidia. WB revealed that epithelial-mesenchymal transition was not involved. Notably, AF293 conidia increased NIH/3T3 growth only in 3DF culture without inducing an apoptotic reaction. RNA-sequencing revealed the increased expression of genes associated with interferon signalling, including MX2; however, the decreased expression of genes associated with the cell cycle was not observed. Conclusions: AF affects both apoptosis of epithelial cells and the growth of fibroblasts. A deeper understanding of the detailed mechanisms underlying Aspergillus-mediated signaling pathway in epithelial cells and fibroblasts will help us to understand the lung microenvironment.