MOLECULAR CHANGES INDUCED BY IN VITRO INVASION OF HUMAN BRONCHIAL EPITHELIAL CELL LINE (BEAS-2B) BY CLADOSPORIUM SPHAEROSPERMUM

Abstract

The conidia of Cladosporium may trigger allergic responses upon inhalation. Other than causing phaeohyphomycosis, Cladosporium sphaerospermum was reported to cause intrabronchial lesions. This study was conducted to investigate the interaction between C. sphaerospermum with human bronchial epithelial cells (BEAS-2B). The conidia were co-cultured with BEAS-2B cells at different durations up to 72 hours. At each time point, adherence and invasion of the cells by the conidia were investigated using immunofluorescence staining. The conidia adhered and were internalised by the epithelial cells. They also germinated and invaded the cells. Changes in BEAS-2B gene expression were assessed using AffymetrixGeneChip® Human Transcriptome Array 2.0 after co-culturing the conidia with BEAS-2B cells for 48 hours. A total of 68 individual genes was found up-regulated ≥ 1.5 folds while 75 genes were found differentially expressed at ≤ -1.5 folds compared with controls. Quantitative polymerase chain reaction was performed and the expressions of all the studied genes were similar to those of microarray findings except for NEDD1. Two-dimensional gel electrophoresis was performed to investigate the protein expressions in the spent culture supernatants collected after co-culturing the conidia with BEAS-2B cells for 48 hours. The gels were then stained with silver stain. A total of 24 protein spots was identified for each control. The molecular weights and pI of the spots ranged from 7 to 45 kDa and 5.6 to 7.7 respectively. However, 3 prominent spots were missing from the treated cells. In conclusion, Cladosporium sphaerospermum is able to adhere and invade BEAS-2B cells. Interaction with the conidia triggered an increase in cell death-related genes and genes related to innate immunity in bronchial epithelial cells.