Interleukin-33 is a regulatory nuclear factor in lung cancer and wound healing

Abstract

Interleukin-33 (IL-33) is an IL-1-like alarmin, and is a ligand for the ST2 receptor. IL- 33 functions as a dual function cytokine, with the ability to induce Th2 immune cells and translocate into the nucleus and repress gene transcription. However, the role of nuclear IL-33 is not completely understood in lung epithelial cells. The aim of this study was to visualise nuclear IL-33 expression in lung epithelial cells and to compare the role of nuclear IL-33 in healthy lung epithelial cells (BEAS-2B cells) compared to a non-small cell lung cancer (NSCLC) cell line (A549 cells). Human A549 cells and BEAS-2B cells were cultured and analysed for nuclear IL-33 via fluorescence microscopy and quantitative real-time PCR at a controlled state. Additional A549 cells and BEAS-2B cells were cultured and physically scratched to mimic the wound healing process, and analysed for nuclear IL-33 via fluorescence microscopy and quantitative real-time PCR, with nuclear IL-33 shown to increase in comparison to control cells. Additional cells were treated with Poly (I:C) and analysed for nuclear IL-33 via fluorescence microscopy and quantitative real-time PCR. Nuclear IL-33 expression was seen in Poly (I:C) treated cells was equal to control cells in both cell lines. Interestingly, when BEAS-2B cells were treated with a combination of scratches and treated with Poly (I:C), they expressed the highest levels of nuclear IL-33. A549 cells undergoing apoptosis were visualised via fluorescence microscopy, showing that nuclear IL-33 is highly expressed in cells undergoing apoptosis. Although nuclear IL- 33 levels are high in cells undergoing apoptosis, apoptosis is not needed to visualise nuclear IL-33 in both A549 cells and BEAS-2B cells. A549 and BEAS-2B cells were cultured and scratched or treated with Poly (I:C) and analysed for H3K27Me3 via fluorescence microscopy. An increase in H3K27Me3 expression was visualised in BEAS-2B cells when cells were combined treated with scratches and Poly (I:C), similar to that of nuclear IL-33 expression. The expression of ST2 was also analysed via fluorescence microscopy and quantitative real-time PCR. ST2 expression did not differ from control to treated in A549 cells. In BEAS-2B cells, ST2 expression was more cytoplasmic than the control cells. Together, these treatments mimic normal wound healing and infection responses, both of which cause cell stress and damage, and would therefore expect to elicit an alarmin response. Our findings support this with scratched and Poly (I:C) treated cells showing an increase in IL-33 expression.

Date of Award	2017
Original language	English